Skeletal Muscle Phosphatidylcholine And Phosphatidylethanolamine Are Related To Insulin Sensitivity

[paymanz]

Ok this is good, this link you posted earlier confirms my suspicion in parenthesis above:


So betaine stimulates almost exclusively PEMT through methylation, while 60% of choline (experimental mouse figure, this will be different in vivo in humans) should go to PEMT.

(I didn't remember if there was a significant pathway through which betaine could convert back to choline or significantly spare existing choline - though still possible this latter case applies in a less experimental scenario)

So if you combine this with the information I posted above, taking TMG or other sources of betaine should produce more unsaturated phospholipids than taking choline and uridine (or CDP-choline, same thing).

[or, if you prefer, methylation in general should produce more unsaturated, so getting less methionine and more choline might be preferable]

Thanks ,thats interesting , probably that is one reason ray doesnt like excess methylation.

But in the same time his diet is filled by methyl donors, except for betaine.

His diet has lots of b12,choline,folate.

 

[paymanz]

Ok this is good, this link you posted earlier confirms my suspicion in parenthesis above:


So betaine stimulates almost exclusively PEMT through methylation, while 60% of choline (experimental mouse figure, this will be different in vivo in humans) should go to PEMT.

(I didn't remember if there was a significant pathway through which betaine could convert back to choline or significantly spare existing choline - though still possible this latter case applies in a less experimental scenario)

So if you combine this with the information I posted above, taking TMG or other sources of betaine should produce more unsaturated phospholipids than taking choline and uridine (or CDP-choline, same thing).

[or, if you prefer, methylation in general should produce more unsaturated, so getting less methionine and more choline might be preferable]

The conversion of choline to betaine is the reason you mentioning betaine(tmg) here?

 

[Terma]

TMG is a proxy for methylation in general. But yeah you also need to know that a significant part of choline becomes betaine, and then a portion of betaine goes to PEMT.

----

So after switching to choline (no TMG and less methionine), which is proportionally better, the next best thing is to try to keep choline in the Kennedy pathway instead of going to methylation. (of course, you still need to consume less linoleic acid too)

I don't know how to do this in general, but the rate-limiting step in Kennedy is relieved by UMP, so in theory having small doses of UMP/uridine with food that go straight to liver (not for high blood levels) would be one thing to do, to make Kennedy consume more choline.

Same for choline, you probably just want to shunt to it to liver as much as possible rather than get high blood levels (-> acetylcholine).

I don't know how far I can take this.

 

[managing]

Fascinating stuff

TMG is a proxy for methylation in general. But yeah you also need to know that a significant part of choline becomes betaine, and then a portion of betaine goes to PEMT.

----

So after switching to choline (no TMG and less methionine), which is proportionally better, the next best thing is to try to keep choline in the Kennedy pathway instead of going to methylation. (of course, you still need to consume less linoleic acid too)

I don't know how to do this in general, but the rate-limiting step in Kennedy is relieved by UMP, so in theory having small doses of UMP/uridine with food that go straight to liver (not for high blood levels) would be one thing to do, to make Kennedy consume more choline.

Same for choline, you probably just want to shunt to it to liver as much as possible rather than get high blood levels (-> acetylcholine).

I don't know how far I can take this.

So if you take a saturated choline product like @haidut 's where would you expect that to effect the cycle? My fear is that it could shunt the cycle in the direction of methylation? I don't have a good feel yet for what the homeostatic mechanism is.

 

[Terma]

Fascinating stuff

So if you take a saturated choline product like @haidut 's where would you expect that to effect the cycle? My fear is that it could shunt the cycle in the direction of methylation? I don't have a good feel yet for what the homeostatic mechanism is.

In theory that product is the best thing available if you space it out. Except I don't know how much gets wasted and how much actually gets where it needs to be (including liver) pre-formed. Otherwise you might as well get choline, spread-out. I would probably take a little uridine anyway for any of it that breaks down.

 

[managing]

In theory that product is the best thing available if you space it out. Except I don't know how much gets wasted and how much actually gets where it needs to be (including liver) pre-formed. Otherwise you might as well get choline, spread-out. I would probably take a little uridine anyway for any of it that breaks down.

"space it out"?

 

[Terma]

"space it out"?

I mean take smaller doses with meals instead of single large doses. For that product I don't know if it really matters that it's with food, just that large doses of choline-containing things never do anything healthy. For uridine it should be both spread out and taken with food, swallowed.

 

[Terma]

Oh, I completely forgot. I looked into this years ago but never had a reason to post it:

A good candidate to feed the Kennedy pathway may in fact be: Fructose. At least, in the liver (not in brain).

It's a well-known inducer of Diacylglyceride (DAG) production in cells (many studies on this, random one: Disparate metabolic response to fructose feeding between different mouse strains). This is part of what leads to elevated triglycerides. Elevated DAG in cells is usually considered cytotoxic.

It just happens, although it's usually not rate-limiting, DAG is also one of the inputs to Kennedy pathway, along with uridine (CTP precursor), or generally synthesis of the phospholipids:

(I don't know what influences the PC- and PE-specific enzymes, I can't read at the speed of Travis)

So, this could be seen in two ways: Kennedy may help to dispose of DAG produced by fructose in liver (what is the extent of this contribution - how much does it take away from triglycerides - I never looked that far), but also, fructose might help promote the Kennedy pathway.

Now I didn't look concretely into numbers to figure out what is the contribution both ways, but you get the idea.

------------

One other thing is, lowering methylation does have some potentially very damaging side effects. Especially if your system is flawed to begin with.

SAMe is involved in the synthesis of things like ubiquinone/CoQ10 in mitochondria (Acid sphingomyelinase-ceramide system in steatohepatitis: A novel target regulating multiple pathways - ScienceDirect / Biosynthesis of Menaquinone (Vitamin K2) and Ubiquinone (Coenzyme Q)).

So, while trying to lower methylation, there a few methylation end-products that might be worth supplementing directly. Others you might not want to supplement, and instead supplement their precursors (like lysine for carnitine), to theoretically soak up the methyl away from PEMT although some of these could be too tightly regulated.

There's tons I can't say for sure, but it gives some lines of inquiry.

 

[paymanz]

 

[Terma]

I accidentally landed on this the other day:
Niacin noncompetitively inhibits DGAT2 but not DGAT1 activity in HepG2 cells. - PubMed - NCBI

Niacin is a widely used lipid-regulating agent in dyslipidemic patients. Previously, we have shown that niacin inhibits triacylglycerol synthesis. In this report, using HepG2 cells, we have examined the effect of niacin on the mRNA expression and microsomal activity of diacylglycerol acyltransferase 1 and 2 (DGAT1 and DGAT2), the last committed but distinctly different enzymes for triglyceride synthesis. Addition of niacin to the DGAT assay reaction mixture dose-dependently (0-3 mM) inhibited DGAT activity by 35-50%, and the IC(50) was found to be 0.1 mM. Enzyme kinetic studies showed apparent K(m) values of 8.3 microM and 100 microM using [(14)C]oleoyl-CoA and sn-1,2-dioleoylglycerol as substrates, respectively. A decrease in apparent V(max) was observed with niacin, whereas the apparent K(m) remained constant. A Lineweaver-Burk plot of DGAT inhibition by niacin showed a noncompetitive type of inhibition. Niacin selectively inhibited DGAT2 but not DGAT1 activity. Niacin inhibited overt DGAT activity. Niacin had no effect on the expression of DGAT1 and DGAT2 mRNA. These data suggest that niacin directly and noncompetitively inhibits DGAT2 but not DGAT1, resulting in decreased triglyceride synthesis and hepatic atherogenic lipoprotein secretion, thus indicating a major target site for its mechanism of action.

So turns out Nicotinic acid inhibits the DGAT2 enzyme and promotes DAG at the expense of Triglycerides (TAG).

Since it's so well-known to modulate blood lipids, is it possible that Nicotinic acid is in fact one of the more important signaling molecules promoting phospholipid formation?

The answer is yes, it's in fact part of its famous HDL-promoting effect:
http://www.jlr.org/content/53/5/941.full.pdf

In cultured human hepatocytes (HepG2),
niacin increased: association of apoA-I with phospholipids
and cholesterol by 46% and 23% respectively, formation of
lipid-poor single apoA-I molecule-containing particles up to
2.4-fold, and pre
migrating HDL particles. Nia-
cin dose-dependently stimulated the cell efflux of phospho-
lipid and cholesterol and increased transcription of ABCA1
gene and ABCA1 protein

Note that this may not necessarily extend to Niacinamide since many of these effects are related to the Nicotinic acid exclusive nicotinic acid receptor effects.

In fact, in another text I can no longer find, it was suggested that the insulin resistance-promoting effects of chronic/inappropriate Nicotinic acid may in part be caused by this slowdown in DAG->TAG, since DAG in overload becomes toxic to cells.

But essentially, this is suggesting that part of the formula for phospholipid generation promotion in liver is choline, uridine, and niacin.

It also suggests that any Niacin consumption should be offset with choline and uridine, but decidedly not for methylation reasons.

-----

COINCIDENTALLY, muscle insulin insensitivity due to saturated fatty acids may also be related to DAG accumulation:
https://www.researchgate.net/public...stimulation_of_glucose_uptake_in_muscle_cells

he increased availability of saturated lipids has been correlated with development of insulin resistance, although the basis for this impairment is not defined. This work examined the interaction of saturated and unsaturated fatty acids (FA) with insulin stimulation of glucose uptake and its relation to the FA incorporation into different lipid pools in cultured human muscle. It is shown that basal or insulin-stimulated 2-deoxyglucose uptake was unaltered in cells preincubated with oleate, whereas basal glucose uptake was increased and insulin response was impaired in palmitate- and stearate-loaded cells. Analysis of the incorporation of FA into different lipid pools showed that palmitate, stearate, and oleate were similarly incorporated into phospholipids (PL) and did not modify the FA profile. In contrast, differences were observed in the total incorporation of FA into triacylglycerides (TAG): unsaturated FA were readily diverted toward TAG, whereas saturated FA could accumulate as diacylglycerol (DAG). Treatment with palmitate increased the activity of membrane-associated protein kinase C, whereas oleate had no effect. Mixture of palmitate with oleate diverted the saturated FA toward TAG and abolished its effect on glucose uptake. In conclusion, our data indicate that saturated FA-promoted changes in basal glucose uptake and insulin response were not correlated to a modification of the FA profile in PL or TAG accumulation. In contrast, these changes were related to saturated FA being accumulated as DAG and activating protein kinase C. Therefore, our results suggest that accumulation of DAG may be a molecular link between

What does this mean?

Essentially, it's essential for saturated fatty acids to be consumed with choline and uridine to promote the incorporation of DAG into phospholipids rather than accumulating DAG and slowly toxicitifrying your cells.

 

[Terma]

Here's another interesting tidbit, although I find this of limited use (because both this forum and I would promote fructose which likely increase DAG/TAG in your liver and which becomes the limiting factor):
Glucose regulates diacylglycerol intracellular levels and protein kinase C activity by modulating diacylglycerol kinase subcellular localization. - PubMed - NCBI

Although chronic hyperglycemia reduces insulin sensitivity and leads to impaired glucose utilization, short term exposure to high glucose causes cellular responses positively regulating its own metabolism. We show that exposure of L6 myotubes overexpressing human insulin receptors to 25 mm glucose for 5 min decreased the intracellular levels of diacylglycerol (DAG). This was paralleled by transient activation of diacylglycerol kinase (DGK) and of insulin receptor signaling. Following 30-min exposure, however, both DAG levels and DGK activity returned close to basal levels. Moreover, the acute effect of glucose on DAG removal was inhibited by >85% by the DGK inhibitor R59949. DGK inhibition was also accompanied by increased protein kinase C-alpha (PKCalpha) activity, reduced glucose-induced insulin receptor activation, and GLUT4 translocation. Glucose exposure transiently redistributed DGK isoforms alpha and delta, from the prevalent cytosolic localization to the plasma membrane fraction. However, antisense silencing of DGKdelta, but not of DGKalpha expression, was sufficient to prevent the effect of high glucose on PKCalpha activity, insulin receptor signaling, and glucose uptake. Thus, the short term exposure of skeletal muscle cells to glucose causes a rapid induction of DGK, followed by a reduction of PKCalpha activity and transactivation of the insulin receptor signaling. The latter may mediate, at least in part, glucose induction of its own metabolism.

 

[Terma]

I haven't looked at every part of the DAG pathways yet [importantly I have no idea how they differ for liver vs other cell types], but you can try to draw some additional conclusions relating to the PE<->PC ratio from the activities of Diacylglycerol Kinases (from study I just posted) and the Kennedy pathway (further above):

Diacylglycerol kinases: at the hub of cell signalling. - PubMed - NCBI

An Unconventional Diacylglycerol Kinase That Regulates Phospholipid Synthesis and Nuclear Membrane Growth

both PA and DAG are the precursors for the synthesis of abundant phospholipids that are used for membrane biogenesis, through the CDP-DAG and CDP-choline pathways, respectively

(note this picture does not contain a line for Diacylglycerol Kinase)

This is what ties it back to the study the OP posted.

All I can is that in my opinion from the facts I do know, the Kennedy pathway is the way to go if you're trying to incorporate saturated fats into your membranes. [But this is from very limited info and maybe the Diacylglycerol Kinases can work toward this as well...]

 

[Terma]

I should've posted this above (to justify the importance of PC synthesis in consuming DAG), but I was already quite sure:
Phospholipid Synthesis Participates in the Regulation of Diacylglycerol Required for Membrane Trafficking at the Golgi Complex

We found that cellular DAG rapidly increased when PC synthesis was inhibited at the non-permissive temperature for the rate-limiting step of PC synthesis in CHO-MT58 cells. DAG also increased when choline and inositol were not supplied.

(Was not thinking about inositol, however, but suppose that makes sense)

 

[Anders86]

Ok this is good, this link you posted earlier confirms my suspicion in parenthesis above:


So betaine stimulates almost exclusively PEMT through methylation, while 60% of choline (experimental mouse figure, this will be different in vivo in humans) should go to PEMT.

(I didn't remember if there was a significant pathway through which betaine could convert back to choline or significantly spare existing choline - though still possible this latter case applies in a less experimental scenario)

So if you combine this with the information I posted above, taking TMG or other sources of betaine should produce more unsaturated phospholipids than taking choline and uridine (or CDP-choline, same thing).

[or, if you prefer, methylation in general should produce more unsaturated, so getting less methionine and more choline might be preferable]

@Joeyd

 

[ddjd]

@Anders86 thanks for brining this post to my attention. very interesting.

@Terma some great info here, albeit a little beyond my level of understanding. Are you saying Uridine, Fructose and Niacin can all help push CDP choline towards the kennedy pathway, i.e. phosphatidylcholine production from CDP.

So it would therefore make sense to take Uridine alongside CDP choline for optimum production of saturated PC

 

[ddjd]

I should've posted this above (to justify the importance of PC synthesis in consuming DAG), but I was already quite sure:
Phospholipid Synthesis Participates in the Regulation of Diacylglycerol Required for Membrane Trafficking at the Golgi Complex


(Was not thinking about inositol, however, but suppose that makes sense)

"Choline phosphotransferase (CPT, not to be confused with carnitine palmitoyltransferase which shares the CPT acronym) transfers the phosphocholine from CDP-choline to diacylglycerol (DAG).There is also an enzyme called choline–ethanolamine phosphotransferase (CEPT) which has dual specificity for CDP-choline and CDP-ethanolamine (and one specific for CDP-ethanolamine), the donation of phosphocholine towards DAG is what finally creates phospholipids such as phosphatidylcholine (the other enzymes that use CDP-ethanolamine instead create phosphatidylethanolamine). This enzyme is not stimulated by incubation with uridine, but is stimulated by nerve growth factor (NGF)."

Nerve growth factor?

 

[Anders86]

"Choline phosphotransferase (CPT, not to be confused with carnitine palmitoyltransferase which shares the CPT acronym) transfers the phosphocholine from CDP-choline to diacylglycerol (DAG).There is also an enzyme called choline–ethanolamine phosphotransferase (CEPT) which has dual specificity for CDP-choline and CDP-ethanolamine (and one specific for CDP-ethanolamine), the donation of phosphocholine towards DAG is what finally creates phospholipids such as phosphatidylcholine (the other enzymes that use CDP-ethanolamine instead create phosphatidylethanolamine). This enzyme is not stimulated by incubation with uridine, but is stimulated by nerve growth factor (NGF)."

Nerve growth factor?

I bet there are some informative post' s on R/Nootropics or Longecity on NGF. I tried the mushroom Lions Mane for this and I believe Gotu Kola also increases NGF. I read alot about NGF and BDNF some years ago, but it seems to rarerly be mentioned in the Peatosphere. My guess is because its not that important..? Noopept also increases this, so I guess Glycine activates it.

 

[ddjd]

But essentially, this is suggesting that part of the formula for phospholipid generation promotion in liver is choline, uridine, and niacin.

I found this study:

"Henneberry et al. (2000) found that human CPT1 showed cholinephosphotransferase activity against several diacylglycerol substrates and required Mg(2+) or Mn(2+)."
OMIM Entry - * 616747 - CHOLINE PHOSPHOTRANSFERASE 1; CHPT1

basically, the last enzyme in the Kennedy Pathway, cholinephosphotransferase (CHPT1/ CPT1), which converts CDP choline to Phosphatidylcholine requires magnesium and manganese.

so on top of the choline, uridine, niacin, fructose, that @Terma suggests, perhaps magnesium / manganese are also helpful.

 

[Terma]

"Choline phosphotransferase (CPT, not to be confused with carnitine palmitoyltransferase which shares the CPT acronym) transfers the phosphocholine from CDP-choline to diacylglycerol (DAG).There is also an enzyme called choline–ethanolamine phosphotransferase (CEPT) which has dual specificity for CDP-choline and CDP-ethanolamine (and one specific for CDP-ethanolamine), the donation of phosphocholine towards DAG is what finally creates phospholipids such as phosphatidylcholine (the other enzymes that use CDP-ethanolamine instead create phosphatidylethanolamine). This enzyme is not stimulated by incubation with uridine, but is stimulated by nerve growth factor (NGF)."

Nerve growth factor?

Thanks. I'm not sure why CEPT would be specifically associated with NGF, but definitely NGF would increase phospholipid production in neurite outgrowth and some proliferating bodies in general: Control of membrane phosphatidylcholine biosynthesis by diacylglycerol levels in neuronal cells undergoing neurite outgrowth

In this thread my eye was mainly on liver, and to stay on thread, muscle phospholipid production/incorporation. I don't know how much NGF would be involved in these, maybe not at all. If it generally increases DAG production (as in the one I just linked) then might make sense in muscles? I'm not sure how much NGF is involved there.

The fructose + niacin + etc. idea is mainly targeted toward liver phosphotidylcholine production. Fructose (and somewhat niacin) should cover the DAG production there, but it's a good point that in other tissues and organs, you'd need something to ensure sufficient DAG production since fructose can't do that locally; so, saturated fat, NGF, ... (possibly even pre-formed omega-3 was involved in an indirect way, there was an unintuitive contribution toward phosphatidylcholine synthesis from it which I can't recall the details; not that it's a great idea; it may have been a stress-like mechanism).

Thanks for the magnesium tidbit, was not aware of that one.

(You must have got that from examine.com, right? Oddly the last line is missing there)

[Note: It's possible in the Ray Peat view that NGF can be viewed as a stress hormone, i.e. hormesis-triggered]

 

[Terma]

@Terma some great info here, albeit a little beyond my level of understanding. Are you saying Uridine, Fructose and Niacin can all help push CDP choline towards the kennedy pathway, i.e. phosphatidylcholine production from CDP.

So it would therefore make sense to take Uridine alongside CDP choline for optimum production of saturated PC

Uridine is already formed in humans from breakdown of oral CDP-choline. You only need extra uridine (oral - not sublingual - with food and carbs) if you take Alpha-GPC, egg yolks, choline bitartrate or choline citrate and you don't consume milk (source of orotate - uridine precursor) or you have the genetic flaw that prevents uridine production through the orotate pathway (unlikely you have this).

Too much, too high uridine too long can probably cause harm - extremely underresearched substance - so am cautious about it. High blood uridine mimics fasting conditions, although so far (2016) this is basically just correlation.

Traditionally Kennedy pathway - in liver, anyway - is limited by CTP:phosphocholine cytidylyltransferase which is limited by endogenous orotate/Uridine/UMP production, but in other circumstances other variables enter such as DAG abundance.

The main point of my posts was just to point out that PEMT is probably responsible for export of polyunsaturated phospholipids from the liver, while the less stress-related Kennedy pathway should tend to produce Ray Peat approved phospholipids. There is a whole other dimension when it comes to tissue- and organ-specific phospholipid synthesis outside liver.