Sunday, December 29, 2013

Protons (33) The mtG3Pdh knockout mice

These mice keep asking me more questions that I'm comfortable with so the post is down subject to further thinking!


Time for a Christmas break methinks! Best wishes all round.

Peter

OK, I've stopped trying to cover every aspect of these mice, some of the more exciting bits really need a whole series on their own. So here we have the slightly truncated version of the original post.



Repost.

Before we come to the consequences of excessive superoxide generation in complex I I'd just like to run through a small part of this rather neat paper on what happens if you virtually eliminate it.


Take a mtG3Pdh knockout mouse and feed it on a very low fat standard style lab chow and it will grow pretty well normally. Bear in mind that both of the diets in the study are very, very low in fat.

Ultra low fat means that dietary fat, especially when PUFA based, is not going to generate any insulin resistance based on electron transferring flavoprotein dehydrogenase reducing the CoQ couple. It's going to have to be mtG3Pdh which controls insulin facilitated calorie delivery. This particular model may not behave as simply on a higher fat diet. There are stacks of unknowns about this model.

Before we come on to anything else, what happens when you inject any old mouse with exogenous insulin?

Simple so long as you have the dose rate carefully chosen, blood glucose falls, cells develop insulin-induced insulin resistance, mouse survives. You have to be modest in your dose but it's not too difficult. We talked extensively about the Somogyi effect back in the Zombie days.

The mice in the present study happen to have been fed a high sucrose/minimal fat diet for 6 months. The two top lines are the wild type and heterozygous knockouts for mtG3Pdh. The lower, terminated, line represents the full knockouts.




















The line is terminated at around 30 minutes because all of the mice were terminated, ie they died of hypoglycaemia. They needed to develop insulin-induced insulin resistance and, without mtG3Pdh, it never came. RIP.

The paper also goes on to show many, many other fascinating things about these mice but the more I try to cover all of these features the more it obscures the main finding. For insulin resistance on a ultra low fat diet you need mtG3Pdh up and running. It may be worth coming back to the effects of fructose and oxygen consumption from this paper but that's another set of ideas.

That's all for today. I just wanted to link these mice to the normal physiological insulin resistance generated by mtG3Pdh (when glucose/fructose is the primary metabolic fuel) and the protons ideas. They all fit together.

Core message: For hyperglycaemia, exogenous insulin or fructose to induce insulin resistance you need mtG3Pdh for effective reverse electron flow through complex I to generate (essential) superoxide/H2O2. This is important. So is going over the top with this normal physiological function, which looks to be rather bad for you.

Peter

Tuesday, December 24, 2013

Protons (32) Post obese insulin induced thermogenesis

Post-obese people are probably rarer than pre-obese people but at least they can be quite conclusively identified. The main problem with most post-obese folks is that they are usually only ephemerally in that state and they rarely achieve a truly "normal" bodyweight. But there are some people out there who have done this. So how do conventional medics get obese people to lose 80% of their excess bodyweight and keep that weight off for more than two years?

Well, it's quite easy. You just rearrange their digestive system to virtually join their stomach to their colon. Tatarinni wrote the paper. Eat, have a bowel movement, eat some more, poo some more. Maybe you have to eat sitting on the loo. Once patients have "adapted" to their bilio-pancreatic diversion they can get down to as few as 3-5 bowel movements a day, allowing them to leave the bathroom occasionally.

This is what you do (I added the red arrow for clarity):















Total remaining absorptive gut is about 250cm long. This works for weight loss. Tataranni's paper is fascinating as it gives us a picture of the metabolism of eight post-morbidly-obese women who are close to an ideal BMI and who have been that way for over two years.

You need the caveat that these people have a markedly maligned digestive system, so may not represent their metabolic state pre-obesity, but they are very interesting never the less. You also could make an argument that these people, given a normal digestive system, would rapidly become obese again. So perhaps they may really tell us something about people who are pre-obese.

The most striking aspect is that they are NOT insulin resistant. Fasting insulin and fasting glucose are quite, quite normal. Their resting metabolic rate is indistinguishable from that of control women.

But they are not quite normal. The response to a 75g oral glucose load shows markedly increased insulin sensitivity.

Let's just emphasise: Post-obese women with long term sustained normal bodyweight have a significantly increased sensitivity to insulin during an OGTT compared with never-obese women.

Fasting free fatty acids are lower, as you might expect, albeit ns in a group size of eight.

Obviously, with limited access to FFAs, the control of metabolic substrate supply at the cell surface must be managed by manipulating GLUT4s using a glycolysis derived input, which of course means mtG3Pdh as the CoQ input to resist insulin's action. This means there must be enhanced glucose (or insulin) induced thermogenesis to achieve this insulin resistance. Here it is in the aftermath of an OGTT:
















The excess energy expenditure is, in part, heat generated by the in-putting of high energy NADH electrons to the CoQ couple without pumping protons.

I floated the concept that glycerol-3-phosphate might be a core protectant against caloric overload on an individual cell basis in the last post, by inducing insulin resistance. I also suggested that the other related function might be the diversion of excess calories to lipid storage, phosphorylated glycerol being essential for intracellular triglyceride formation.

So here we have another interesting set of graphs from Fig 5:




















The first striking thing is that in post-obese people an oral load of 75g of glucose induces a respiratory quotient of greater than one. Second is that, during this time, lipid oxidation becomes negative. It was only ever half that of the never obese controls to begin with. As the authors comment:

"After the oral glucose load, the RQ increased more in P0 [post-obese] than in C [control] subjects, reaching values > 1. Thus, lipid synthesis exceeded lipid oxidation in P0 subjects 45 min after the oral glucose load and continued to do so for 40 more min".
 

What is happening is that these women accept glucose in to their cells very easily. The glucose is converted to pyruvate, this is decarboxylated via the pyruvate dehydrogenase complex to yield CO2 which increases the RQ. The acetyl CoA formed is exported to the cytoplasm as citrate. Obviously the citrate is formed by combining acetyl CoA with oxaloacetate, the latter can also be derived from pyruvate but this time via carboxylation, and hence the TCA never turns. Oxygen is never consumed. RQ >1.0.


So these post-obese women are exquisitely sensitive to insulin, in particular they are remarkably efficient at de novo lipogenesis and at the inhibition of lipolysis.

Were they like this before becoming obese? I think so. Why they might be like this is interesting to think about from the mitochondrial point of view.

Might there be any way of controling their weigh gain without the need for gross malabsorption secondary to removing most of their gut?

Well, you could take insulin out of the equation by simple ketogenic eating and see what happens...





I was going to leave this as an interesting snippet but there are a few add-ons to these ideas.

Some artificial models of this effect are available from various "pre-obese" rodent models. I had a think about them here.


Edward emailed me a link to this paper about a post-obese case report from Dundee. This man has a normal digestive system, he simply didn't use it for 382 days.

Look at the glucose levels in Table 1:











NB, these glucose levels are all very, very low. The authors feel that these values are real. Perhaps he may have been morbidly obese, yet still insulin sensitive. You need to have retained some insulin sensitivity to attain massive obesity without limiting weight gain by the transition to diabetes. But anyhoo, the trends are what interested me.

What we need to look at is the first column, fasting glucose levels. If we ignore day 355, where there was some sort of a hiccup, FBG was around 35mg/dl. This is quite low but the chap was in extended starvation so this might not be surprising. This is the level of glucose under deep, deep physiological insulin resistance. Ignore day seven value of re-feeding because metabolism will, in all probability, still be far from normal and the chap was only consuming liquid glucose at this time.

Instead I looked at day 55 of re-feeding, while he was on 1000kcal of a mixed diet. His FBG was very low, about two thirds of what it was during fasting. This chap, like the Italian enterectomy women, was very, very insulin sensitive. Insulin drives fat storage as well as hypoglycaemia.

He kept the weight off for at least 5 years. Two points: This chap was a psychological outlier! Second is that 1000kcal/d, if it is Food based, is a LC diet even if it is also a low-everything-else diet too.

Enjoy the winter festivities!

Peter

Saturday, December 21, 2013

Protons (31) insulin induced thermogenesis in the Pima

I thought I might just put this snippet up as it's been lying around ready to go for some time. I've tried to tidy up some of the worst sentences. Happy Solstice! Here we go.

Back when talking about the Pima paper I skipped over insulin induced thermogenesis, a fascinating subject and a phenomenon distinctly lacking in the obese, if they are insulin resistant. This is the pattern of IIT, from normal glucose tolerance through to diabetes. From Fig 2:














The phrase "insulin induced thermogenesis" is, at first glance, a complete oxymoron. It is difficult to imagine any way in which insulin, that most effective suppressor of free fatty acids, might uncouple respiration to generate heat. The primary brown adipose tissue technique is to use UCP1, which depends on free fatty acid availability. But there are other ways to generate heat in addition to uncoupling the proton gradient. It is worth noting that some of the thermogenesis is "obligatory", by which the authors mean the exothermic storage of glucose as glycogen. I'm rather more interested in the "facultative" component.

Brand's group have been hard at work again and have this (excellent) paper out:

Sites of reactive oxygen species generation by mitochondria oxidizing different substrates

most especially the lovely figure 1 (use the link to get the legend, it's a good summary of ETC energetics and "non-stressed" superoxide production):










It is an abstraction of the ETC, grouping inputs by their redox potential rather than physical location and is now becoming pretty inclusive for most electron donors. All mitochondrial NADH inputs are through complex I at -280mV and these electrons flow from here towards the positive potential of +600mV, provided by oxygen at complex IV. They do work in the process, pumping protons to set up the delta psi which can be "wasted" to generate heat when needed. Without uncoupling, the process is efficient and energy from the electron is largely conserved.

The interesting point is that mtG3Pdh inputs to the CoQ couple which has, we can now see, a redox potential of +20mV.

Specifically, mtG3Pdh is taking a cytoplasmic NADH, which could theoretically be shuttled to the mitochondrial matrix, and hence to complex I, at -280mV, and inputting it to the ETC at +20mV. The energy lost by skipping from -280mV to +20mV would normally pump four protons and now appears as heat.

After a glucose load any oxidation of the abnormally elevated FFAs of insulin resistant people still provides a continuous +20mV input using ETF dehydrogenase's FADH2 acting on the CoQ couple, which is ultimately derived from the FADH2 of the first step of beta oxidation, ie it's FADH2 transporting electrons all the way, there is no energy wastage when using fats to limit insulin's action. In the absence of these inappropriate FFAs, the correct way to reduce the CoQ couple is using mtG3Pdh which shuts down insulin's action at the cost of generating heat because it uses NADH, stepped down to FADH2, as a direct input at the CoQ level. We want a reduced the CoQ couple when there is metabolic oversupply as a reduced CoQ couple allows reverse electron flow through complex I and insulin resistance.

Insulin resistance, via reverse electron flow through complex I, is what is wanted, heat is a by-product.

Insulin, which activates a long chain fatty acid ligase to generate acyl-CoAs for anabolism/triglyceride formation, might well be expected to simultaneously generate the glycerol 3 phosphate needed for the triglyceride backbone. The diversion of FFAs to intracellular triglycerides can be viewed as protection against excess metabolic substrate supply.

It strikes me as appropriate that the same molecule might also be used to generate the insulin resistance which limits substrate oversupply supply, if there is no fat available.



I think I might leave this as a short post before we go on to the post-obese and insulin induced thermogenesis. And possibly on to mtG3Pdh knock out mice.

Peter

Wednesday, November 27, 2013

Protons (30) Uncoupling and metabolic rate in insulin resistance

I wanted to look at insulin resistance, uncoupling and metabolic rate. If we just review the effect of an intravenous bolus of palmitic acid on an anaesthetised rat we can see that the bolus produces a period of increased oxygen consumption, ie an increased metabolic rate, in a then-uncoupled healthy rat. From Curi again:



















This next graphic is looking at glucose oxidation, rather than oxygen consumption, from the same paper.















The left hand graph shows what happens under basal metabolism, ie glucose is being taken up by isolated muscle cells without help from insulin facilitated GLUT4 translocation. Fatty acids uncouple, ATP levels fall, there is an increase in glucose oxidation to compensate, ATP levels are corrected. Presumably some of the fatty acids get metabolised too.

On the right is the effect under supra maximal insulin. We have no idea of dose response curve to insulin from this study, it describes either using none or using 10mU/ml. That's mU, not microU! At a concentration of 10mU/ml insulin will overcome any suggestion of insulin resistance, short of a knockout model. Insulin supports glucose oxidation, uncoupling increases this. The set up is not designed to look at insulin resistance as might be related to that uncoupling. But the effects on overall metabolic rate, at 5.6mmol of glucose, are quite clear cut.



What if that elevated FFA level was maintained long term?

As adipocytes become progressively more resistant to the the anti-lipolytic effect of insulin (why is another whole ball game), plasma free fatty acids rise even under levels of insulin which should be suppressing them. Unless these free fatty acids are converted to CoA derivatives they are will uncouple respiration. This should reduce delta psi and increase metabolic rate.

A reduced delta psi will not support reverse electron flow through complex I. The essential insulin induced pulse of superoxide, converted to H2O2, will not occur. There will be fasting insulin resistance. This paper spelled it out. In brief:

The insulin signalling cascade is tonically restrained by a phosphatase which deactivates the insulin/receptor complex (which activates itself by auto-phosphorylation) as soon as the process tries to get started. For insulin to signal you need to have an elevated delta psi which allows a nanomolar pulse of H2O2 to cripple this phosphatase and so allow the insulin/receptor complex to get signalling.

With reduced delta psi this isn't going to happen. We have enhanced insulin resistance of starvation until the time when food arrives.

You can increase delta psi, of course, to get insulin working. Increasing delta psi requires increased electrons in to the respiratory chain through complex I. In the blunted insulin signalling situation of low delta psi we can't use GLUT4 transporters but we can, given high enough plasma glucose levels, get sufficient glucose in to the cell to generate enough of a delta psi to allow the pulse of H2O2 and its downstream effects to occur. So overcome the inability of insulin to signal in the presence of FFAs.

The cost is that an elevated blood glucose level is needed. This is what we look at with the ratio of fasting glucose to fasting insulin, the HOMA score. An elevated HOMA score is a marker of UNCOUPLING at the delta psi level in mitochondria. It should be associated with an increased metabolic rate in proportion to the degree of fatty acid induced uncoupling.

Does this happen in real life? These data are from the Pima but the pattern is generic in insulin resistant states:









Note first that the changes in FFA concentrations are statistically non significant, but that the trend is nicely upwards with insulin levels

The authors comment:

"Alternatively, FFA may contribute to increased RMR via stimulation of mitochondrial uncoupling proteins (UCPs) (53,54). As early as 1976, Himms-Hagen (53) suggested that FFAs stimulate UCP-1. More recently, elevated FFA concentrations were reported to stimulate UCP-3 expression in rats (54)"

Bear in mind that as people progress from NGT through IGT to diabetes there are not only progressive changes in blood lipid and glucose levels but also progressive damage to mitochondria per se, which makes comparing a healthy rat to a metabolically challenged human being slightly dubious.

But the changes make sense.

If we look at the post prandial situation we have, after a carbohydrate containing meal, the combination of chronically elevated FFAs with acutely elevated glucose. There will be a high delta psi as soon as blood glucose rises high enough (supra physiological) to allow non-GLUT4 uptake to elevate delta psi high enough for insulin signalling. At this time point the mitochondria allow insulin to function. We can now translocate GLUT4s to the cell surface and start to lower postprandial hyperglycaemia by pouring metabolites through glycolysis or in to glycogen stores.


At the same time, among insulin's many diverse functions, the activation of free fatty acids to their CoA form increases, with a view to anabolic or storage functions. I would presume a different CoA ligase directs the activated fatty acids to oxidation. There is quite a group of LCFA CoA ligases.


At this point we lose the freedom of free fatty acids, they are ligated to CoA and suddenly become effective inhibitors of uncoupling rather than facilitators. We are now set up for the post prandial state. As soon as we have access to glycolysis combined with beta oxidation we have the possibility to generate marked reverse electron flow through complex I and re-inhibit the action of insulin using much greater generation of H2O2 than is needed for insulin's initial activation.

Metabolically, the mitochondria do this at this time to stop caloric overload in any individual cell, by diverting excess calories to storage in adipocytes. From the NADH:FADH2 ratio, long chain saturated fats do this best. Monounsaturates appear to be designed to allow a normal combination of glucose and fatty acid oxidation and PUFA fail to generate adequate insulin resistance to protect an individual cell (including adipocytes) from an overload of metabolic substrate. In the immediate post prandial state saturated fats can best protect cells from an absorptive excess of metabolites. These fatty acids are already present in supraphysiological levels, whatever has been eaten.

The elevated insulin needed to maintain post prandial normoglycaemia will, if the adipocytes are able to respond at all, divert fat from the circulation and into those adipocytes. This is the simple ability of insulin, and cellular resistance to insulin, to limit metabolic injury when calories are present in excess of immediate needs.

                                                    *****

Under inappropriately elevated FFAs there is an initial failure of insulin's action due to depressed delta psi during fasting and a subsequent post-meal failure of insulin's action due to inappropriately elevated fatty acid metabolism through electron transport flavoprotein dehydrogenase's FADH2 when combined with high delta psi.

To me, this looks very much like impaired metabolic flexibility, reduced to the level of delta psi and superoxide. I like it.

Peter

Sunday, November 24, 2013

Death by dogma

It's amazing what you can find on the internet when you click on a link. I stumbled over this recently:

Premature aging in mice activates a systemic metabolic response involving autophagy induction

I picked up this gem of a paper from, of all places, a blog with somewhat limited enthusiasm for ketogenic eating. I'll just go through the results section of the paper, giving a staccato summary of each paragraph, because you have to be sure of exactly what a group have found before you consider whether you agree with their conclusions. These mice lack the ability to form prelamin A correctly, instead they form progerin, and they age very rapidly. Here we go with the results section:

A mutation which damages nuclear architecture and causes premature aging also increases autophagy.

The abnormal protein formed (that prelamin A precursor known as progerin) appears to be the cause of premature aging and to be associated with increased autophagy (in this model).

Other models, XPF and CSB/XPA, of rapidly aging mice (both with defective DNA repair processes) do the same thing but without accumulating progerin, especially they increase basal autophagy. So this upregulated autophagy is common to several models of premature ageing, not just the prelamin A model.

mTOR signalling is switched off. Really switched off.

The PI3K-Akt pathway, which usually activates mTOR, is not the explanation.

AMPK is switched on. Really switched on.

Stopping the response to DNA damage (p53 knockout) does not stop enhanced AMKP activity. So we are not looking at extra autophagy to recycle damaged DNA.

Next we get on to glucose. The five hour starved level of glucose is low, around 38% of control value. Insulin is low too.

In the liver things are strange.

Phosphoenolpyruvate carboxykinase and glucose-6-phosphatase are up-regulated, both are important for gluconeogenesis.

Puryvate kinase (a glycolysis regulator) is not up-regulated. So where is the glucose going if it's not going to glycolysis?

Glucose from gluconeogenesis appears to end up in the liver as glycogen granules, without needing glycogen synthase to be up regulated. This glycogen can be accessed if needed.

At the same time fatty acid producing genes are up regulated. Glucose is being converted to fatty acids. Genes associated with fatty acid oxidation are up regulated too. And a fatty liver develops. Very interesting.

Pyruvate dehydrogenase kinase-4, key for switching from glucose to fat burning, is strikingly upregulated. These mice burn fat. They reject glucose. And they die of precocious aging!

All of the "good" markers indicating longevity in many models are fantastic in these mice. The end product is early death.

Metabolically, everything appears to come down to PGC 1-alpha. It's production is very upregulated. This cofactor appears to responsible for the switch from glucose to fat based metabolism.

End of results summary.

This is where the paper stops.

On the basis of these findings a concern expressed in the discussion is that elevated PGC 1-alpha drives autophagy, which is initially adaptive but might become maladaptive when chronically activated. This is a potentially valid concern (there is an autophagy triggered form of cell death distinct from apoptosis and necrosis) but we have to bear in mind that there is zero data to support this specific concern provided in the paper. That's all of the results section summarised up above.

The authors are well aware that the reason for rapid aging is the genetic defect in nuclear architecture formation. This leads, indirectly, to genomic instability which immediately puts this model in to the same category as other premature aging models such as XPF and CSB/XPA, both of which have defects in DNA repair, also as mentioned above.

So why do the cells of these animals go in to a state of AMPK driven, mTOR inhibition dependent, persistent autophagy?

They do this because they have a severe ATP deficit. High levels of AMP per unit ATP drive AMPK.

Why is there insufficient ATP?

Let's have a read at Nick Lane's essay Mitonuclear match: optimizing fitness and fertility over generations drives aging within generations. Here's the quote:

"Oxidative phosphorylation involves the transfer of electrons through a succession of redox centres in respiratory chains, from an electron donor such as NADH, to a terminal acceptor such as oxygen. A slowing of electron transfer means that respiratory complexes become more highly reduced, which increases their reactivity with oxygen, corresponding to a rise in free-radical leak [25]. A slowing of electron transfer is the most likely outcome of any mismatch between mitochondrial and nuclear genomes. The reason relates to the mechanism of electron transfer. If the gap between adjacent redox centres in respiratory chains is increased by just 1 A, electron transfer by quantum tunnelling slows down by an order of magnitude [26] and free-radical leak should rise accordingly. Given that hydrogen bonds and Van der Waal’s forces act over distances in the range of 1–2 A, it is likely that any changes to optimal subunit interactions would disrupt the distance between redox centres by more than 1 A, slowing electron flow and increasing free-radical leak. Thus, a rise in free-radical leak is the predicted outcome of virtually any subunit mismatch, and indeed has been reported [27, 28]"


Question: How well might the electron transport chain function in the mitochondria of a cell which has a permanent defect in its ability to repair nuclear DNA damage?

Answer: Three separate mouse models, engineered to have defective DNA repair, have chronically activated AMPK.

I think these mice are "starving" with full stomachs because they cannot generate ATP. They have progressive un-repaired changes to the nuclear DNA coding for (amongst many things) electron transport chain components which means these proteins simply don't fit the proteins from mtDNA.


Soooooooo. Essentially all of the changes in these mice could be traced back to inadequate ATP generation, with the added bonus of excess ROS generation to further damage the "unrepairable" DNA.

The extended autophagy is a total red herring, sort of.

I picked this paper up as a FB link "liked" by Chris Highcock. The linked blogger is so impressed by the lethal effect of autophagy that he appears to consider that diet-induced autophagy is a "worthless dogma" and avoids it, not liking dogma. That's fine by me, we all have our quirks.

Unfortunately for this autophago-phobic concept, and possibly for the poor chap himself, it turns out that if you take a prelamin A mutant mouse and treat it with rapamycin you will actually promote even MORE autophagy. So, if autophagy is the cause of premature aging, things should get worse. Yes? The actual result is that:

"Here, we report the discovery of rapamycin as a novel inhibitor of progerin [defective prelamin A], which dramatically and selectively decreases protein levels through a mechanism involving autophagic degradation. Rapamycin treatment of progeria cells lowers progerin, as well as wild-type prelamin A levels, and rescues the chromatin phenotype of cultured fibroblasts..."

or just have the title:

Autophagic degradation of farnesylated prelamin A as a therapeutic approach to lamin-linked progeria.

As an approach, it works. Further increasing autophagy rescues prelamin A mutant mouse cells. RIP autophagy as a "cause" of accelerated aging.




I like Chris a lot, he's a really nice chap. Luckily the sort of hill walking he does (still love your Pentland pictures on FB, if you read this Chris) he will be regularly and repeatedly activating AMPK with subsequently increased autophagy. Exercise does this. So does the "misery" of ketogenic eating.

Actively changing your diet to avoid autophagy, based on a progerin model which can actually be rescued by increasing autophagy, just might be a booboo. Imitate with caution.

Peter

BTW It's sort of nice looking at technical papers which (superficially) challenge my low carbohydrate biased perspective. Knowing you are in a correct paradigm makes dissecting them a rather relaxed process when you start form a position where the world makes sense. Perhaps this is dogma.

Thursday, November 14, 2013

Ketoacidotic death in lactation!

Laura forwarded me the link to this epic study:

A gestational ketogenic diet alters maternal metabolic status as well as offspring physiological growth and brain structure in the neonatal mouse.

It has a very very clear message. This is the first paragraph of the results section:

"Lactation in KD [ketogenic diet fed] Dams Leads to Fatal Ketoacidosis. In the initial trial phase, 4 KD dams remained with their biological litters post parturition, and during lactation. However, lactation appeared to cause severe physiological strain to all KD dams. Soon after parturition they started exhibiting signs of high stress, as was also apparent by them cannibalizing their litter. Measurements of their blood glucose and ketone revealed elevated values (Glucose: ∼20 mmol/L and Ketone: ∼6 mmol/L), indicating development of ketoacidosis. This ketoacidosis rapidly progressed to a fatal metabolic state, leading to the death of the KD dams within a few days post parturition"

I hope that is clear. No beating about the bush.

These folks are cutting edge. They know how to get impressive results.

Take home message: If you wish to survive lactation do not, UNDER ANY CIRCUMSTANCES, base your diet on CRISCO. Do not do it.

My wife seems to have survived two ketogenic lactations in pretty good shape. Daniel's school is well in to spelling test this term. He is the only kid in his class to have made no mistakes so far. It doesn't look as if we have broken his brain. No Crisco.

Of course Sussman et al blame the ketosis. They keep very quiet about the Crisco:

TD.96355 Ketogenic Diet: "Vegetable Shortening, hydrogenated (Crisco) 586.4g/kg"

Want to die? Always ask for Crisco by name. Crooks.

Peter

Tuesday, November 12, 2013

Protons (29) Uncoupling with fatty acids

Trying to work out exactly what is happening in a given functional component of the inner mitochondrial membrane is not the most simple of undertakings. For anyone who wishes to bend their brain a little you could do worse than working through Federenko's paper on the likely structure/function of UCP1 in brown adipose tissue. I think the original pdf was sent to me by Alex, some time ago. Although it is looking at UCP1 I think we can reasonably assume other UCPs work in much the same manner. This set of line doodles summarises the paper:












Here's the explanatory text:

(A) The simplest mechanism of steady H+ IUCP1 induced by LCFAs. UCP1 operates as a symporter that transports one LCFA and one H+ per the transport cycle. First, the LCFA anion binds to UCP1 on the cytosolic side at the bottom of a hypothetical cavity (1). H+ binding to UCP1 occurs only after the LCFA anion binds to UCP1 (1). The H+ and the LCFA are translocated by UCP1 upon conformational change, and H+ is released on the opposite side of the IMM, whereas the LCFA anion stays associated with UCP1 due to the hydrophobic interactions established by its carbon tail (2). The LCFA anion then returns to initiate another H+ translocation cycle (3). Charge is translocated only in step 3 when the LCFA anion returns without the H+.


All nice and simple, compared to how complex it was to work all of this out. In plain English: The (removable) fatty acid flip-flops back and forth, passing a proton each time. UCPs absolutely MUST have access to long chain fatty acids to function. The LCFAs must be free, ie NOT be activated. Sticking a large CoA moiety on to the red dot (which is the carboxylic end of the LCFA) will completely inhibit any activity in UCP1 as there is then no negatively charged binding site on the fatty acid to allow it to ferry protons, repeatedly, down their concentration gradient back in to the mitochondrial matrix.

So fatty acids may just be slightly important to uncoupling. Uncoupling may be a Good Thing or the converse, depending on your point of view or your carbohydrate intake.



This leads us on to Curi's group and their 2006 attempt to look for the effect of FFAs on uncoupling in tissue culture, in isolated mitochondria and even in whole live rats. When you see a line in the methods which specifically states "in Krebs–Ringer bicarbonate buffer containing 5.6 mM glucose" you know you are in for a treat. You have to have read as much cell culture literature as I have to realise how precious a line like this is. All you normally get is the type of medium, probably the brand name and the supplier, but oops, forgot to mention it has, or might have, or might not have, 25mmol of glucose in it. Or some other random amount. Duh. The easy way to tell (when not specified) is that if saturated fats cause apoptosis in cell culture, be certain that glucose is >20mmol.

Anyhoo. Here we go:
















This is from first generation harvested and cultured skeletal muscle cells. The fluorescence rises with inner mitochondrial membrane potential, delta psi. Antimycin A blocks ATPase so hyperpolarises the membrane, CCCP is a chemical uncoupler and so reduces it. These are just tests to show the prep works. The caprylic acid is useless (it works well on isolate mitochondria but the cytoplasm probably stops MCTs reaching the mitochondria without adding CoA while they are on their way there). Palmitic acid and linoleic acid uncouple, like a mild version of CCCP.


















You can show exactly the same effect in chronically cultured myotubules, just another cellular prep.





















This is our first look at isolated mitochondria. This is a graph of the same delta psi sensitive fluorescent dye plotted against time. The graph is upside down because, in real life, delta psi is negative. You add SMM (skeletal muscle mitochondria) to the observation medium. They fire up and delta psi increases. This is the curve dropping downwards from the SMM arrow. In the middle of the 2 minute bar, palmitic acid is added and delta psi decreases (upward flick in the upside down graph) marked by the PA arrow. The bottom line is what happens if you have added guanidine di phosphate, GDP, an inhibitor of UCPs. At the end they also added CCCP to fully uncouple the mitochondrial membrane and show that delta psi collapses.

Note, you can only show the inhibitory effect of GDP when the CoQ couple is oxidised. A reduced CoQ couple stops GDP's inhibitory effect on uncoupling. This gives a mass of contradictory studies in the literature, needless to say. The control of uncoupling as a fascinating area, perhaps another post.













And this graph is looking at the rise in oxygen consumption induced by uncoupling using assorted fatty acids. Again, mitochondria, so caprylic acid works, though never as well as the longer fatty acids. Note the lack of GDP effect, the CoQ couple must be reduced in this prep. BSA (bovine serum albumin) eliminates the uncoupling as it "hoovers-up" all available FFAs.



Does this uncoupling happen in intact animals? Yes. A stack of caveats, but yes. Ratties were bolused with intravenous palmitate or alcohol (As the control??!!?? Alcohol is not inert, even if it doesn't uncouple) and then oxygen consumption was measured:






















Palmitic acid uncouples.

Right, that will do for now. The plan is to look at FFAs and insulin resistance next, within this framework.

Peter, chronically uncoupled.

Tuesday, October 01, 2013

Polycystic Kidney Disease and mTOR

I think I'm pretty well out of blogging time for the next month or so, so the post looking at fatty acids, uncoupling and insulin resistance will have to sit on the back burner while I work on an anaesthesia project. A friend emailed me a paper with this rather nice diagram of the probable aetiopathology of polycystic kidney disease. Whenever I see mTOR driving pathology I always think of ketogenic eating to obtund the process. If you carry PKD genetics I don't see any other remotely sensible option...























No Reverse Warburg Effect here. I love the 2-deoxyglucose too. If there was ever a way of faking a ketogenic diet, this is it. More so than ketone esters! A bit of physiological insulin resistance or a drug to block glycolysis? Or how about a modern mTOR inhibitor? I'll leave it open to guesswork (or Pubmed if you must) what a ketogenic diet does to mTOR signalling.

Peter

Saturday, September 21, 2013

Electron Transport Chain image

Just off to bed. Wow, do I have wild Saturday nights! Had to share this lovely pic. One of the better representations of the ETC I've ever seen, lifted from here.












Like.

Peter

Wooo and the snps

There seems to be quite a bit of interest going on in the LC Hardcore at the moment and I'm sat here, under my stone, looking at UCPs as prime mediators of the insulin resistance of fasting and membrane pumps in the origin of life as relates to lactate and extracellular pH in cancer. And I should really be working on a dead-lined anaesthesia project. Wooo and Toxic ("I read your potatoes, and the news will never be good" LMAO) have both brought up 23andme and, surprise surprise, Wooo has enough snps on assorted ion channel genes to have her in a loony bin several times over. She concludes that a ketogenic diet gets her a normal life.

Obviously I have nothing to disagree with here.

What I would comment on is that a very, very large chunk of the "normal" population may not be quite as normal as she suspects. Having frank bipolar disease with severe enough presentation to give you a clear cut "label" is quite rare. Having severe depression to the point of complete loss of functionality or schizophrenia to the point of obeying the voices completely, whatever they command, are all equally rare. But shades of grey appear to be very common and I don't see that many normal people are all that normal. Undoubtedly we all have snps on all sorts of genes. That's genetic variability and is essential to provide a pool for the species to adapt through.

That many mental illnesses are essentially metabolic, and that ion channels have a great deal to do with neural energy demands, is not exactly unexpected. Sid Dishes emailed me this rather interesting review (BTW finding this in Nature is rather like reading a massive endorsement of the Atkins diet in the Sun or the Daily Mail, Sid feels paradigm shift) looking at exactly the metabolic aspect. Yet another email needing a thankyou not sent yet. Thanks Sid. Look at this quote from the abstract talking about central neurons:

"it is now clear that they [psychiatric illnesses] are associated with impairments of synaptic plasticity"

and tie that back to peripheral neuropathy, here's Chowdhury on peripheral nerves:

"The consequences of suboptimal ATP supply for the distal nerve fiber are numerous: (1) collateral sprouting and plasticity will be retarded, (2) this will lead to gradual pruning of the axonal network and shrinkage of sensory innervation fields, and (3) end organs of myelinated fibers within the dermis will lose innervation and function (see Fig. 3)"

My italics.

The parallels, to me, make it sound like we are talking about the same process. I would suggest that hyperglycaemia breaks the mitochondrial population and ketosis is an excellent sticking plaster. Which snps you have determine which neurons break first.

If you also have metabolic snps which limit your ability to avoid hyperglycaemia on the SAD in addition to neural snps which make for "upper limit of normality" energy demands within hyperglycaemia compromised neurons, you are on your way to the Funny Farm. Or a ketogenic diet.

I, for one, am very glad Wooo hit the ketogenic diet arm.

I have said that I think it is unlikely that humans are in any way adapted to a diet which regularly and severely induces hyperglycaemia. Had Wooo been born in to a normoglycaemic environment, what would the effect have been of her ion channel snps on perception?

If you think Wooo is "normal", you are crazy.

Personally, I think we need people who are three standard deviations from the population norm when it comes to insight and perception. This may well be down to ion channels and snps of the Wooo flavour... I don't see that we would get too far, species wise, if we were all Taterheads with ion channels which allowed tolerance of hyperglycaemia until Alzheimers (type 3 diabetes) kicked in, and yet only allowed as much insight in to anything as a turnip has. Of the latter, there is a lot of it about, we have more than enough.

Blog on Wooo.

Peter

Friday, September 06, 2013

Omega 3s and G-protein coupled receptors

Let's just summarise the role of omega 6 fats in Sauer's rat model of cancer:

In the lab situation rapid hepatoma tumour growth needs either arachidonic or linoleic acids. The acids must be taken up in to the hepatoma cells, they must be acted on by lipoxygenase to produce 13-hydroxyoctadecadienoic acid, better known as 13-HODE. 13-HODE appears to be the mitogen which promotes rapid cancer growth. 13-HODE looks like a repair signal gone wrong in cancer cells. Omega 3 fatty acids block omega 6 fatty acid uptake in to hepatoma cells. That's all well and good but the reason I got in to this paper was omega 3 PUFA signalling, rather than those omega 6 issues...



OK, Sauer starts to give some pointers on the function of omega 3 fatty acids in health. That's interesting, as I'm no great lover of any sort of PUFA when I view them from the Protons perspective, yet omega 3s seem to come out pretty well, certainly at low doses. You know my fall back, omega 3 PUFA don't always behave like omega 6 PUFA because they get used as signalling molecules blah blah blah. My own inability to tie the molecular structure of omega 3s to their clinical effects is very frustrating! That they probably act are sites "above" the ETC suggest that they act as what I view as 'high level signals".


Well they do.


The signalling appears to be through a G-protein linked receptor with all of the usual cAMP cascade that follows binding of a ligand to such a receptor. What I found particularly interesting was the effect produced on fat pads of normal rats when EPA (other papers from Sauer suggest all omega 3s act on whichever receptor is involved) was added to the perfusate.

OK, here is a neat little graph taken from here:
















This is from fed rats. In the fed state the FFA uptake by the inguinal fat pad of a rat is about 6 mcg/min/gram, white open squares.

Adding EPA at 0.84mmol/l (a bit supraphysiological for EPA but let's let that ride) and FFA uptake by the fat pad drops to zero, or close to zero. Or, in fact, you could argue a suggestion of fatty acid relase, shown as a negative uptake value. Black circles. Fatty acids are not taken up, they end up in the venous effluent in the experiment, plus a little extra.

Whooooah, so do FFAs go through the roof when you take fish oil IRL??

Well no. That's because of this graph from here in the same paper:















Here we have the free fatty acid release from the inguinal fat pad of a healthy rat who has been starved for 48 hours. Fatty acid release is trundling along at about 3mcg/min/gram until EPA is added, again at around 0.8mmol/l. The release of FFAs, in the fasted state, is eliminated. Table 1 in the same paper shows you can get this effect of halting lipolysis in starved rats with under 0.3mmol/l EPA.

Both effects are mediated through a G-protein coupled receptor, ie high level signalling compared to electrons and superoxide in the electron transport chain.

Obviously there are a number of serious problems with this paper but, as a proof of concept, I buy it. I doubt DHA or alpha linolenic acid would work as well (or the group would have used them for this proof of point exercise!) and I think the levels of EPA used produce a very artefactual "switch-like" effect which is probably a graded response. I doubt 0.8mmol/l or even 0.3mmol/l of EPA is exactly physiological but...

Let's suggest that there is a progressive removal of the influence of adipocytes from the FFA flux in/out of plasma as the level of omega 3s in arterial blood increases. Omega 3 fatty acids render adipocytes irrelevant to free fatty acid levels in the plasma.

That is one hell of an idea.

Next we need a brief look at hepatoma cells, again the graph is provided by Sauer and it shows that omega 3 fatty acids, in a G-protein coupled receptor manner, completely turn off the uptake of ALL fatty acids in to hepatoma cells.

















If, and it's quite a big "if", the same effects apply to hepatocytes as well as hepatoma cells, we then have a very straightforward mechanism for the protective effects of omega 3 fish oils on hepatic lipidosis. From my point of view this is quite real as there are pretty convincing papers showing that cats, in real life, can be largely protected against the potentially fatal hepatic lipidosis of rapid weight loss by modest doses of omega 3 fatty acids.

Soooo while omega 3s stop the release of all FFAs from adipocytes, they simultaneously stop the uptake of all fatty acids in to the two primary storage organs for fatty acids, adipocytes and liver.

Do plasma FFAs go up or down?

They do, of course, go down. A paradox? Next paper.

Health warning: This paper is so steeped in VLDL and ApoB lipophobia that it makes difficult reading. But there is so little published on FFAs and omega 3 supplementation that it's worth the ondansetron to read it. It's looking at how omega 3 supplements might lower fasting triglycerides, which are the devil incarnate for CVD risk. A huge chunk of VLDL comes from FFAs released from adipocytes and their subsequent repackaging by the liver. Apparently, and I quote from the abstract:

"FO [fish oil] counteracts intracellular lipolysis in adipocytes by suppressing adipose tissue inflammation"

A bit like insulin resistance is caused by "inflammation". Well, maybe it's that simple. They have taken the concept of high level signalling to its 2013 pedestal without looking for basic mechanisms. They have placed the G-protein coupled receptor on to macrophages in the fat pads, which subsequently control the adipocyte lipolysis using cytokines. I haven't checked how good this concept is. Sauer never looked that deeply. Looks a bit modern to me.

Personally I would guess that there are similar receptors on both adipocytes and hepatocytes, but the review does not seem to cover the ability of omega 3s to inhibit general fatty acid uptake by these two tissues. Ah well.

What they do argue is that omega 3 fatty acids upregulate lipoprotein lipase, pretty well whole body. Of course liver and adipocytes ignore this fatty acid bonanza, as above. LPL upregulation is what I needed to know from this paper.

So where do "spare" fatty acids go to? They go to muscles. Upregulated lipoprotein lipase (heralded as the saviour from elevated fasting triglycerides) allows increased lipid release from VLDL to lower those fasting triglycerides. But it's worth bearing in mind that cells do not "see" VLDL, the LPL is on the vascular endothelium and the cells behind the vessel wall only ever receive "free" fatty acids. These are not labelled as from albumin, VLDL or chylomicrons.

Slight aside for later: It seems likely that chylomicrons are going spill their lipids via that same LPL, worth remembering.

The story in the review can be sumarised as omega 3 fatty acids block the release of FFAs from adipocytes and increase the activity of lipoprotein lipase pretty well whole body. VLDL drops, FFAs drop. All is happy in the cardiovascular system. If you believe.


Various "bits" of omega 3s, especially the lipid peroxides of DHA, are signals for mitochondrial biogenesis. I had a paper which specified which lipoxide was most effective but must have missed the "save" button. Mea culpa yet again. There are hints here.


That's a very neat story, which has more than a grain of truth to it.

Why is it like this? What does it mean, physiologcally? Speculation time:


Omega 3 fats come from plants. Mostly from chloroplasts. Where do humans get their omega 3s from? Certainly not from plants. If we did then the rabid Dr Furhman would not be (correctly) recommending DHA supplementation (along with B12) to avoid brain collapse on veg*n diets. Actually, this link is quite funny when cited by Mc-Starch-Dougall:

"There is no evidence of adverse effects on health or cognitive function with lower DHA intake in vegetarians"

Well, I found it amusing. It's almost the converse of the neurological truism which states that being concerned about having a neurodegenerative disease probably means you don't actually have one.

Anyhoo. Away from the coast we have to get our DHA from animals (or buy algae derived supplements). They get it from grass. There is DHA present in adipose tissue of herbivores just as much as it is present in lipid membranes of their cells. My suspicion is that DHA is a signal to your metabolism that you have just eaten animal fat, from an animal who's food chain starts with grass [or algae]. The more fat you eat, the stronger the signal. We do not need much DHA overall for our brains as it is well protected in this site, but we might well be using it at low levels as a [G-protein coupled receptor sensed] signal to target metabolic adaptation to process fat. So is McDougall correct that veg*n "brain" tissue is OK, despite their periphery being depleted? Shrug.

Fish oil supplements? Well, using our "dietary fat is here" marker to pharmacologically modify some perceived CVD risk factor, without the appropriate change in source of metabolic fuel supply, looks to me to be of very limited value. Large intervention trials do show some benefit from omega 3s provided you do your stats well enough, you have a large enough population to pick up a very small effect and you give a high enough dose. But they do not seem to be any sort of panacea. Especially of you are avoiding dietary fat while "faking" the signal that you have eaten dietary fat...

This is not exactly surprising when you try to pick the likely physiology apart. I like the concept of DHA as an animal fat signal.

Peter

Final thought: Do we need omega 3 PUFA at anything above the most minimal levels if we are in saturated fat based ketosis? Of course I don't know. But the signal to cope with starvation is palmitic acid (physiological insulin resistance), not DHA. I live in starvation mode, not on a mixed diet with only intermittent access to healthy ruminant fat. I have long wanted to look at the selective release of FFAs from adipocytes in extended starvation. My suspicion is that in the early days after glycogen depletion palmitic acid is preferentially released over other lipids, PUFA are not needed/wanted. By a few weeks all the palmitate is gone and whatever is left then gets released. People like David Blaine suddenly start to feel weak, wobbly and are probably hypoglycaemic once they run out of palmitate and have to release less saturated fats. Two to four weeks if you carry some spare weight. Sauer's rats had only ever been fed a low fat omega 6 based diet and had no serious palmitate reserves, PUFA release came early for these.

Tuesday, September 03, 2013

Axen and Axen: The tradition continues

Another superb abstract, hot off the press, on LCHF diets. The data are suggested to be utterly clear cut, solid, and supportive of the physiology of LC eating which I have been espousing for many years now.



The conclusions are criminal. There are 13 authors. None seems to have read Kinzig et al's 2010 paper showing not only this very effect but also showing its complete reversal by a few carbohydrate based meals.


That omission, by 13 people on the author list, is what is criminal. The lack of understanding of the basic physiology of carbohydrate restriction even without Kinzig, by people in what claims to be nutrition research, is criminal. The blood on their hands, from dialysis patients, is criminal.



If even one of the authors has read Kinzig it leaves you wondering about the ethics in the group. If they haven't read the literature...

Disclosure: I haven't seen the full text.

Peter

BTW I just Pubmeded "ketogenic" + "insulin" + "resistance" and Kinzig was hit 24, primarily because 2010 is ancient history and the hits come in date order.

Hat tip to Liv for the link.

EDIT

Laura gave us this in the comments: "They actually cite the Kinzig 2010 paper in their discussion saying that their results match and that the results "could" be reversible... and then they leave it at that".

You have to ask what the lead in time to a study like this is. It strikes me as possible that Kinzig pipped them at the post by 3 years but they went on with the study as they had the funding but couldn't add a re feeding arm because they had no study ethics approval for this. Just trying to be kind, probably a mistake. Or perhaps they are just LC bashers as per usual. The cardinal sign, of using the name "Atkins" in the abstract, is not a good marker for an ethical group. But Kinzig is correct. Reversal is absolutely nothing a newbie LCer wouldn't pick up in 10 minutes on the internet.

END EDIT

Thursday, August 29, 2013

Ketones, without the side order of Danish Pastry please

Here is a discussion paper from Denmark. It is a deeply satisfying read, well worth overcoming the slight oddities of grammar which seem to have come from it being written in Danish as a first language. What they are doing is taking the concept discussed by Nick Lane (which they cite) about the intracellular selection of mitochondria under bioenergetic stress and putting a testable molecular framework in place. Obviously, from the Hyperlipid perspective, just look what they place at the top of the list as one of their factors for mitochondrial health. Here's the whole conclusion section:


Conclusions

This perspective deals with the notion that adaptive stress responses to respiratory challenges and stimulation drive natural selection of genetically and epigenetically inherited properties of mitochondria:
  • When brain energy turnover increasingly depends on ketone body or fatty acid metabolism rather than on glucose, sparing of complex I and proliferation of mitochondria is beneficial to overall mitochondrial health.
  • High glucose availability for oxidative phosphorylation, on the other hand, establishes a state of low selection pressure with increased accumulation of lesions.
  • Intermittent non-chronic insults with increased ROS production benefit mitochondrial health and promote healthy aging and increased longevity.
  • In healthy tissue, transient non-lethal insults such as chemotherapy, hypoglycemia, or hypoxic challenges, select mitochondria that are more resilient to subsequent challenges. These mitochondria are better adapted and more numerous.
  • Stressful challenges with increased ROS levels, followed by subsequent recovery and treatment with biogenesis-promoting agents, yield mitochondria with greater respiratory capacity than mitochondria treated with biogenesis-promoting agents alone.
These claims have specific and testable implications, the resolution of which can revise the general understanding of the role of mitochondrial challenges in healthy aging.




OK, 6.06am here, time to fry some egg yolks in butter. No taters for me.

Peter

Sunday, August 25, 2013

Starvation and cancer growth: Sauer vs Lisanti

Preamble: There has been some puzzlement recently among the LC hard core about the main stream antagonism against LC as an approach to disease management. I share their puzzlement. Stan currently has a post here and Wooo has one here. Why do people have to fake data to support an incorrect idea or to abandon techniques which work? Weird. But that's their problem. What frightens me more is when people have an idea in serious science but are disturbing in the conclusions which they come to based on it (I don't usually doubt the data, I'm innocent that way). It particularly scares me when supportive citations are cherry picked while closely related contradictory citations are omitted. Especially when the omitted citations have enormous explanatory power. I came across this unpleasant clash of research thinking accidentally through ron's comment on a Protons post. I was unaware of Sauer's work but have been meaning to blog about cancer and metabolic coupling for some time. Finding that Sauer was in the citation list of Lisanti's coupling paper has pushed me enough to stick this post up. The refs (all free full text) you need to make up your own mind are in the text below. I'm not sure that "enjoy" is quite the correct word. Here we go.




Over in the comments to the Protons summary post ron linked to this paper showing, rather nicely, that sustained fasting markedly promotes cancer xenograft growth. Sauer comments in the paper that the group had noticed this previously and this study appears to be a formalisation of that observation. They had an "Oh, that's interesting" moment and, being scientists, investigated rather than burying it. Here is one of a choice of several graphs:



















The bottom lines are the tumour weights, the top lines the animal weights.

Sooooooooo, living with normal-for-starvation levels of ketones and and free fatty acids promotes cancer growth in these particular models, like wildfire.

I have been heard to comment, on more than one occasion, that I have personally been "fasting" for the last 10 years. I just keep replenishing my fat loss using dietary butter. I have had elevated ketones and free fatty acids, 24/7, for much of the last 10 years, probably to starvation levels.

I sort of like Sauer. He wanted to know what happened in starvation to promote cancer growth. As a 1980s physiologist he then did lots of operations on lots of rats which we would rather not go in to in great detail. But he got results.

Amongst the things they did was to perfuse cancer xenografts in live rats with blood from non cancer bearing rats who were in the fed or fasted state. Joined the "donor" rats directly to the arterial supply to the tumour, using various bits of tubing, all very cunning. The cancers only grew rapidly when perfused with blood from starved rats.

They then took blood from fed rats and engineered it in to various reconstituted blood-like fluids resembling the blood from starved rats, by adding assorted fatty acids, and perfused the tumours to see what it was that made them grow.

Palmitic, stearic and oleic FFA supplementation was inactive in promoting tumour growth.

Linoleic and arachidonic promoted growth, really well. That is very scary.

Aside: When people come to look in earnest at ketogenic diets for cancer management the omega 6 content of adipocytes is going to be one hell of a confounder. You will almost need to eliminate weight loss in order to eliminate or at best reduce the release of omega 6 PUFA if the patient has been living on soy oil or Flora for a lifetime... Not easy. End aside.

Got high cholesterol? Want to lower it? Use polyunsaturated acid based margarine! Want to grow a cancer? Hmmmmmm.

Personally I'll settle for butter or 90% cocoa chocolate with palmitic or stearic acids. I suppose I ought to 'fess up about ketones. Well, no. There has to be a pause here.

If you had a concept which ought to show that ketones were a super-fuel for cancer (there are folks with this viewpoint) you might want to cite Sauer and the papers which show that something about fasting or ketosis promotes cancer growth. Which is exactly what this group did in this paper:

"Ketones and lactate “fuel” tumor growth and metastasis. Evidence that epithelial cancer cells use oxidative mitochondrial metabolism".

Nice title. These are the refs they used:

21. Sauer LA, Dauchy RT. Stimulation of tumor growth in
adult rats in vivo during acute streptozotocin-induced
diabetes. Cancer Res 1987; 47:1756-61.
22. Goodstein ML, Richtsmeier WJ, Sauer LA. The effect
of an acute fast on human head and neck carcinoma
xenograft. Growth effects on an ‘isolated tumor vascular
pedicle’ in the nude rat. Arch Otolaryngol Head
Neck Surg 1993; 119:897-902.


Now, this group is very, very good. They have this concept that fibroblasts are enslaved by cancer cells and forced to perform glycolysis but then abort their own TCA and ox phos, supplying lactate and ketones, both derived from pyruvate, to the cancer cells which then use their own mitochondria to fuel cancer cell growth. It's probably correct.

In support of this concept they injected, intraperitoneally, half a gram per kg of lactate or half a gram per kg of beta hydroxybutyrate daily and got increased metastasis with lactate and increase cancer growth with beta hydroxybutyrate. Probably this really happens.

But there are some holes in this study. The ketones supplied to the mice carrying the cancer xeonografts were given by intraperitoneal injection and no one knows what blood levels were reached. Possibly quite high for a while. They never measured them, that I can see. Even well funded dieters measure their ketones.... Let's assume they go so high, whole body, as to actually mimic the sort of levels produced in the minute extracellular gap between a slave fibroblast converting glucose to ketones and pumping them directly on to the surface of an adjacent master cancer cell. We don't know what that level is either, but both get the desired effect on cancer growth to support the paradigm.

BTW, another complete aside, the locally-supplied, fibroblast-generated ketones and lactate are UTTERLY glycolysis dependent. If the Warburg effect is not happening in cancer cells, the reverse Warburg effect looks to be VERY susceptible to sudden onset normoglycaemia affecting the fibroblasts in metabolically coupled systems. The ketones/lactate come from glucose in this set up, not from lipolysis or anaerobic exercise! End aside.

So the question is, when comparing Sauer and Lisanti, what happens when you feed an in-vivo cancer xenograft with PHYSIOLOGICAL doses of ketones by continuous perfusion, using starvation levels?

Sauer of course, did check this. He took blood from fed rats, added ketones to it without omega 6 FFAs and used the blood to directly perfuse a series of cancer xenografts. He doesn't actually give us a concentration for the ketones he used (Edit; without looking up ref 10: OK, I checked ref 10, 4-ish mmol/l in the control rats, just about where I live) but he does appear to be a very interested in teasing out the cause of the effect, so I'll buy that he used the concentration he had measured in the blood of starved rats, which supported cancer growth so well.

When he had finished with the neutral  effects of palmitic, stearic and oleic acids and the growth promoting effects of linoleic and arachidonic acids, this is what he has to say about ketones:

"Finally, perfusion of normolipemic blood enriched in the ketone bodies (10) had no effect on [3H]thymidine incorporation in tumors growing in fed adult rats (data not shown)."

Doesn't bode too well for therapies based on the Reverse Warburg effect from Lisanti's group targeting mitochondria. Did they not read all of Sauer's papers? Or did they really read them all and cherry picked the ones they wanted? Which idea scares you most? The cancers grow under the influence of omega 6 PUFA derivatives, NOT ketones. Sauer says so. Believe which ever group you like. I'm biased and I rather like Sauer.

Peter



Addenda.

It is very simple to fit omega 6 PUFA FFAs in to the Protons concept of cancer fuelling. I'm still working at why omega 3 fatty acids are protective in these models, they shouldn't be. In cirrhosis models they behave exactly as they should do, promoting cirrhosis as the omega 6s do, but more so. There is a link missing here somewhere. Sigh! I hate "higher level signalling" as an explanation, always seems like a cop out to me. What happens at basic energy metabolism level should give the answer...


Also Sauer specifically looked at cancer utilisation of ketones, lactate and assorted other fuels in some detail here. Some cancers can and do use ketones, but I don't see plasma ketones or lactate as superfuels for cancers in the real world. They get used, but I still see local glycolysis in fibroblasts as the major pathway supplying them. I'm fine with the Reverse Warburg effect. Targeting mitochondria will be a booboo.

Thursday, August 08, 2013

Protons so far, some sort of summary!

We appear to have two basic states of the electron transport chain. There is the situation under fasting or ketogenic dieting conditions. Here delta psi is low, complex I throughput is low and there is plenty of FADH2 input through electron transporting flavoprotein dehydrogenase coming from the first step of beta oxidation of real fats, like palmitic acid. With a low delta psi it is near impossible to generate reverse electron flow through complex I so activation of insulin signalling is rapidly aborted by the continuing action of tyrosine phosphatase.

This is the insulin resistance of starvation. Without it death from hypoglycaemia would be routine after a day or so without food.

Next is the state of the electron transport chain proteins under the influence of insulin signalling. How this is achieved is currently outside my reading but I think it is perfectly reasonable to assume that specific electron transport chain proteins will be phosphorylated as a direct result of insulin signalling being active. With a large supply of NADH to complex I and a restricted supply of fatty acids due to insulin acting on adipocytes there is a high membrane voltage, high throughput of electrons down the ETC via complex I but no reverse flow because there is a minimal input via electron transporting flavoprotein dehydrogenase's FADH2.

These are the two simple extremes of organisation under "isocaloric" conditions and neither generates significant reverse electron flow, ie there is minimal superoxide production at complex I.

Under hypercaloric conditions, usually an elevated supply of both glucose and fatty acids, we have the high delta psi, high FADH2 input through electron transporting flavoprotein dehydrogenase from beta oxidation and so significant reverse electron flow through complex I to signal that more than enough calories are available to the cell.

Under simple glucose based caloric overload mtG3P dehydrogenase steps in in the place of electron transporting flavoprotein dehydrogenase and supplies an FADH2 input to signal the need for hypercaloric insulin resistance. This seems a perfectly reasonable approach to hyperinsulinaemic hyperglycaemia.

Under normal physiology I would expect blood glucose to remain under 7mmol/l at all times, probably under 6mmol/l, provided the food eaten is food and the physiology processes used are undamaged. Even under caloric overload with a baked spud.

What do we really mean by caloric overload?

Overload is the utterly normal response to eating any meal. ANY meal. As soon as the rate of calorie absorption exceeds the post prandial metabolic requirement, we need to store the excess calories. The development of individual cell insulin resistance is utterly normal under these conditions. Blood glucose, blood lipids and blood insulin rise. Fat is diverted to adipocytes. Glucose is diverted to glycogen stores.

All of this is achieved by reverse electron flow through complex I generating a physiological response. The acute storing of calories is essential. This is how we do it.

The diversion of glucose to the brain in starvation is induced by failure to sustain insulin activation due to lack of sufficient mitochondrial membrane potential needed to signal that it's OK to respond to insulin. Low insulin is helpful and low glucose is essential for this process.

I think this summarises the Protons thread to date.

Perhaps we can go on to look at some pathology sometime. Mix 'n' match of the two situations is not a good idea.

Peter

Monday, August 05, 2013

Prostate cancer and citrate and maybe omega 3s

A while ago, when I was looking through various publications from Chowdhury, I found this one: Prostate cancer cells over express mtG3P dehydrogenase. That's interesting. Why?

Normal prostate cells are special. They don't do the TCA. Glycolysis is fine. Pyruvate conversion to citric acid is also fine. Aconitase is not. Aconitase is deliberately inhibited by Zn retention and the citric acid of the citric acid cycle, which cannot be further metabolised in the said cycle, is then exported in to the prostatic fluid. In large amounts. Mitochondria are not used (much). This is hardly a recipe for over expression of mtG3P dehydrogenase.

Aside: I'm assuming the citrate is used to fuel the mitochondria of sperm. Simply dropping citrate on to the TCA of sperm looks like adding N2O/petrol injection to a standard saloon car engine. Maximum power output at the cost of maximum stress. Only the fastest get to the egg and only best survive the journey, which seems like a good idea when looking for the sperm with the best nuclear-mitochondrial match for fertilisation... End aside.

If we look at the paper on Zn, the TCA and mitochondria in prostate cancer (PCa) we can see that PCa cells lose Zn induced inhibition of aconitase and take off with a large supply of NADH from the TCA, a smidge of FADH2 through complex II and go towards that metastatic ratio of NAD+/NADH. Of course citrate concentration in semen plummets.

So PCa cells use the TCA and oxidative phosphorylation, ie they use mitochondria, to burn citrate derivatives. Normal prostate cells don't. Prostate cancer cells routinely perform beta oxidation. Not so normal prostate cells.

Equally interesting, as Loda's group point out, Fatty Acid Synthase (FAS) appears to be an oncogene in PCa cells. That, to me, suggests that while some of the citrate may well enter the TCA there is also a net synthesis of fatty acids outside the mitochondria. Fatty acid synthesis is a cytoplasmic process. Exported citrate provides acetyl CoA as the raw material for fatty acid synthesis.

BTW I don't doubt that prostate cells do use fatty acids in combination with "normal" levels of glycolysis, but Liu's fascinating paper here, supporting near exclusive fatty acid oxidation in PCa cells, is a classic example of stacking the deck to prove a point, with subtle transitions in graph labelling between tritiated 2-deoxy-glucose (an inhibitor of glycolysis!) and "glucose". There was no glucose, except the deoxy molecule. Oddly enough, glucose and 2-deoxy-glucose are not the same! While I'm completely accepting of the up-regulation of beta oxidation in this cancer, the near complete shutting down of glycolysis looks like pure artefact. They compare metabolic preference by looking at palmitate depletion from the palmitate-only culture medium, which is normal. Then they looked at 2-deoxy-glucose depletion from the 2-deoxy-glucose medium. The whole point of 2-deoxy-glucose is that, while it can be phosphorylated by hexokinase, further metabolism is completely blocked by the lack of hydroxyl group on the second carbon of the molecule. It may get taken up by cells, but it is never bulk metabolised. So it never gets depleted from the growth medium. Duh. I wonder if they expected this result...



I've also looked at Load's ideas about "futile cycling". This is the concept that acetyl CoA, from beta oxidation of fatty acids within the mitochondria, is exported as citrate to form cytosolic acetyl CoA to be converted to palmitate, which is re-imported in to the mitochondria to provide acetyl CoA to re-export as citrate.... Doesn't make sense to me. If you have functional mitochondria and a functional ETC, why bother if it's futile?

But we have seen something very similar in the past. FAS activation seems to be an important feature of TFAM knock out adipocytes. There is no functional complex I in TFAM knockout cell mitochondria and acetyl CoA provides limited FADH2. Without complex I you need FADH2 to drive the ETC, NADH won't hack it. Converting acetyl CoA from any source repeatedly to palmitate generates significant FADH2 during its re-oxidation. It's cycling, but it's not futile. You get something from it which you cannot normally get from pure acetyl CoA, so long as complex I is dysfunctional. Of course you get horrible levels of NADH too, but...


So you have to ask yourself: Do prostate cancer cells lack complex I? Logic says they must do.

Well, what do you know, Parr et al point out:

"For example, a 3.4∆ associated with PCa, removes the terminal region of ND4L, all of ND4, and nearly all of ND5 (Maki et al., 2008; Robinson et al., 2010)"

ie there is commonly a 3.4kb deletion of mtDNA which codes for a very large chunk of complex I in prostate cancer cells. This deletion, the paper suggests, appears to occur BEFORE the cells convert to aggressively cancerous forms.

So what cripples complex I? Well you could make all sorts of guesses about this, especially if you are a lipophobe. There is no doubt elevated free saturated fatty acids, in the presence of hyperglycaemia, will drive completely unreasonable numbers of electrons the wrong way through complex I and a great deal of collateral damage might well result from this process. If you have elevated FFAs you would be insane to raise your blood glucose level. "That's Mr Potato Head to you" (Toy Story 1).

How about simple hyperglycaemia? If you can generate enough free radicals from hyperglycaemia to induce some mitochondria functional you are then in a position to start using those mitochondria. Feeding through mtG3P dehydrogenase's FADH2 to the CoQ couple, while the NAD+/NADH ratio is horribly low from glycolysis, allows plenty of reverse electron flow when you really don't want it. For neurons, which don't do a great deal of beta oxidation, this is my guess for the extensive oxidative damage to complex I seen in PD and AD. Loss of complex I in a neuron, which doesn't do beta oxidation, is going to be disatrous. But in prostate cancer cells? Completely unreasonable superoxide generation appears to trash the mtDNA, as Parr pointed out. Conversion of citrate to fats allows survival under these conditions.

Now let me see, what did Chowdhury say about PCa cells and mtG3P dehydrogenase?????????? Up-regulated is the word. No cell is going to produce mtG3P dehydrogenase without functional mitochondria (and glycolysis) and mtG3P dehydrogenase bypasses a broken complex I, in a similar manner to electron transferring flavoprotein dehydrogenase does. Hyperglycaemia is an interesting concept for generating this cancer.






So....... Do PUFA, particularly omega 3 PUFA, give you prostate cancer? As per the suggestion from the observational association here. Probably not. No more than butter or FAS-produced palmitate give you prostate cancer. But PUFA are really quite special, certainly once the damage is done. They supply significantly less FADH2 input to the electron transport chain per molecule than saturated fats do under beta oxidation conditions, omega 3 PUFA being significantly worst than omega 6 PUFA. So here we have specific fats behaving as suppliers of NADH in rather higher amounts than saturated fats do and FADH2 in rather lower amounts. We have a lack of complex I in PCa cells, so supplying NADH is a recipe for metastasis and a poor fuel for the electron transport chain... In PCa cells acetyl CoA from PUFA is a sitting duck for export as citrate with conversion to palmitate and re-beta oxidation, to maximise FADH2 production. Oxidation of omega 3s via acetyl CoA and its subsequent synthesis and re oxidation as palmitate is not futile.

I have no issue with omega 3 fatty acids as signalling molecules, we clearly need some. I would be very cautious about bulk omega 3s, as I would about bulk omega 6s, as a source of calories.

We are looking here at a potential survival/growth mechanism in the behaviour of cells with severely damaged mitochondria, using any pathway they can to generate ATP. But thinking that it was the the omega 3 PUFA which broke the mtDNA in the first place might be a big mistake. Hyperglycaemia appears to be a far better recipe for mtDNA damage through hypercaloric insulin resistance, N-1a, reverse electron flow, etc gone to excess. PUFA are poor generators of FADH2 during beta oxidation so probably don't drive a lot of reverse electron transport through complex I. And never forget that even the bête noire of fatty acids, palmitate, is harmless in the face of normoglycaemia despite being an excellent generator of FADH2 and reverse flow.



Finally, Parr's group consider the damaged mitochondrial genome to be en-route to a situation where apoptosis becomes very difficult:

"As deletion-driven mtgenome depletion advances, cells become more resistant to cell death stimuli, in comparison to their parental cell lines (Cook and Higuchi, 2012), allowing proliferating cells to escape apoptotic control."

One step towards immortality for PCa cells, excepting the unfortunate destruction of their host organism.

Peter

Monday, July 22, 2013

Physiological insulin resistance again

I started the Protons thread with the simple question: What is the difference, from the metabolic point of view, between the energy supplied by fat vs that supplied by glucose derivatives.

This gives a simple picture of insulin resistance as a metabolic technique to limit caloric entry in to an individual cell under conditions of excess availability. NADH, tending to come from glucose, drives complex I to generate a decent inner mitochondrial membrane potential (delta psi). Feeding substrate in at other access points to the electron transport chain's CoQ couple, be that electron transporting flavoprotein dehydrogenase, mtG3Pdehydrogease, NADPH dehydrogenase or others, reduces that CoQ couple and promotes reverse electron flow through complex I, superoxide generation and insulin resistance. This is the insulin resistance seen so clearly when you pay folks to over-eat, assuming you feed them crapinabag. The exact mechanism of this failure of insulin to act is not clear, but large amounts of H2O2 act at several points to inhibit the activation pathway. Of course an intramitochondrial mechanism would be really neat, or some sort of complexing of the insulin/receptor with ETC proteins. Hard to say what we will find here in future, but an interesting area.

What about the insulin resistance of starvation? Do we have the same phenomenon of reverse electron flow through complex I as the mechanism?

So now we have to think about ketones with normolglycaemia. Back in my early days of looking at mitochondria I spent many hours with Veech's seminal paper on mechanical work generated by isolated rat hearts, pumping fat-free fluids spiked with glucose, ketones, glucose/insulin or glucose/insulin/ketones.

Ketones alone do exactly what maximal glucose/insulin do in terms of mechanical work, but by a completely different mechanism. Ketones produce a DROP in delta psi. This reduces uncoupling because there is a much lower voltage pushing protons back in to the mitochondrial matrix. This means that even with a lower delta psi ATP production is maximised (plus a few other changes) and so is the ability of the muscle to pump.

Insulin/glucose together maintain a high delta psi but modify the ETC proteins to improve efficiency, probably involving covalent bonding. I would assume phosphorylation is key.

Mechanical work was perfectly well maintained on ketones vs glucose/insulin, no need for a high delta psi with the ketones. Of course, no one is going to generate superoxide from complex I when the mitochondrial matrix is at a mere -120mV. To generate reverse electron flow it is the high value of delta psi which, when there is enough NADH per unit NAD+, puts an electron on to oxygen via FeS N-1a in complex I.

But under conditions of ketosis, be that ketogenic isocaloric eating or simple starvation, it is axiomatic that somatic insulin resistance is essential to spare adequate molecules of glucose for that little bit of brain metabolism which cannot be met by ketones alone. You need insulin resistance exactly when ketones remove the key driving potential needed for insulin resistance...

The trick lies in insulin activation. Insulin's action both generates and requires a small burst of superoxide. The superoxide is generated intramitochndrially by reverse electron flow through complex I. The superoxide is converted to H2O2 which diffuses to the cytoplasm where it inhibits the enzyme which normally deactivates the insulin/insulin receptor complex. With the reduced delta psi induced by pure ketones this is not going to happen, the insulin receptor rapidly deactivates and we have a simple mechanism for the physiological insulin resistance of ketosis/starvation.

To summarise: Superoxide in large amounts from complex I signals excess calories in the cell and inhibits insulin's action for cellular protection.

Superoxide in nano molar concentrations is essential for insulin's activation and is not made when ketosis lowers the potential across the inner mitochondrial membrane.

The two phenomena are both utterly essential and quite separate.

That makes me happy

There is a mass of detail of this process laid out in this paper H2O2 Signalling Pathway: A Possible Bridge between Insulin Receptor and Mitochondria. It makes interesting reading. I love the stuff on antioxidants causing insulin resistance and Ian recently resurfaced the old paper about supplementing with Vitamins C and E blunting exercise induced improvement in insulin sensitivity.

Bear in mimd that an awful lot of this work comes from tissue culture, transgenic mice, isolated mitochondria, all the usual suspects, so accept with caution.

But it makes sense to me

Peter