methyl-donors choline and methionine differentially alter hepatic carbon metabolism tawny l....
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Methyl-donors choline and methionine differentially alter hepatic carbon metabolism
Tawny L. Chandler, Courtney L. McCourt, Sandra J. Bertics, Barbara A. Barton, and Heather M. White
Methyl donation is needed for DNA methylationPrevention of oxidative stressPrevention of apoptosisEnergy metabolismProtein synthesis
Methyl group competition by pathways
Methyl Group Metabolism
Methyl groups come from methyl donors
methionine (1)
choline (3)
betaine (3)
folate (5-methyltetrahydrofolate; 1)
Methyl Group Metabolism
VLDL Packaging and Export
Cole et al., 2012Rinella et al., 2008
Choline Methionine Deficient Diet in Rodents
Methyl Group Metabolism
Choline
Phosphatidylcholine
VLDL packagin
gphospholipids
for cell membranes
Phosphatidylethanolamine
Methionine
BetaineDimethylglycine
HcyCysteine
glycineglutathione
SAH
SAM
phosp
holip
ase
D
BHMT
MATSAHH
MS
5-MTHFTHF
CH3
White
Cell Culture Model
Allows for testing several concentrations and combinations
Eliminates confounders of other changesPrimary Hepatocytes Culture
Chandler et al., 2015
Bovine Methyl Group Metabolism
0.033 0.1 2 4.50.0160.0300.1000.300
Choline, mM
dL M
et, m
M
Design notes:Mimics in vivo concentrationsConcentration and methyl group equivalents
Chandler et al., 2015
Bovine Methyl Group Metabolism
0.033 0.1 2 4.50.0160.0300.1000.300
Choline, mM
dL M
et, m
M
Does this mimic the transition cow state?
Chandler et al., 2015
Bovine Methyl Group Metabolism
0.033 0.1 2 4.50.0160.0300.1000.300
Choline, mM
dL M
et, m
M
0.033 0.1 2 4.50.0160.0300.1000.300
Choline, mM
dL M
et, m
M
1 mM Fatty Acid Cocktail
Chandler et al., 2015
Main Effects vs. Interactions
Chandler et al., 2015
0
0.2
0.4
0.6
0.8
1
1.2
1.4
[met], mM
Arb
itra
ry u
nit
s
[choline], mM 0.033 0.1 2 4.5
No interactions, main effects shown
Methionine Regeneration
Choline
Methionine
BetaineDimethylglycine
HcyCysteine
glycineglutathione
BHMT
MS
5-MTHFTHF
Chandler et al., 2015
BHMT
0.033 0.1 2 4.50.58
0.60.620.640.660.68
0.70.720.74
[choline], mM
P = 0.8654
0.016 0.03 0.1 0.30
0.10.20.30.40.50.60.70.80.9
[methionine], mM
P = 0.3603
Methionine
BetaineDimethylglycine
Hcy
BHMT
arbi
trar
y un
its
arbi
trar
y un
its
Chandler et al., 2015
Methionine Synthase (MS)
0.033 0.1 2 4.50
0.2
0.4
0.6
0.8
1
1.2
[choline], mM
P = 0.0152Linear: P = 0.0037
0.016 0.03 0.1 0.30
0.2
0.4
0.6
0.8
1
1.2
[methionine], mM
P = 0.0026Linear: P = 0.0021
MethionineHcyMS
5-MTHFTHF
arbi
trar
y un
its
arbi
trar
y un
its
Chandler et al., 2015
BHMT During Fatty Acid Challenge
0.033 0.1 2 4.50
0.10.20.30.40.50.60.70.80.9
no FA FA
[choline], mM
FA: P = 0.0462
0.016 0.03 0.1 0.30
0.10.20.30.40.50.60.70.80.9
no FA FA
[methinonine], mM
FA: P = 0.0462
arbi
trar
y un
its
arbi
trar
y un
its
Chandler et al., 2015
MS During Fatty Acid Challenge
0.033 0.1 2 4.50
0.2
0.4
0.6
0.8
1
1.2
no FA FA
[choline], mM
0.0160.03 0.1 0.3
-2.22044604925031E-160.20.40.60.8
11.21.4
no FA FA
[methinonine], mM
FA P = 0.0001 FA P = 0.0001
arbi
trar
y un
its
arbi
trar
y un
its
Chandler et al., 2015
Methionine Regeneration
Choline
Methionine
BetaineDimethylglycine
HcyCysteine
glycineglutathione
BHMT
MS
5-MTHFTHF
Increased dL met decreases MS Increased choline increases MS
Choline may serve a role in methionine regenerationFatty acid load increases BHMT and decreases MS
Preference for pathway that produces antioxidants
Chandler et al., 2015
PEMT
Choline
Phosphatidylcholine
VLDL packagin
g
Phosphatidylethanolamine
Methionine
PEMT
No change in PEMT with dL Met
0.016 0.03 0.1 0.30
0.5
1
1.5
2
2.5
3
[methionine], mM
P = 0.7012
arbi
trar
y un
its
Chandler et al., 2015
VLDL
Quantification is challenging due to differences in lipid profile of ruminant VLDL
Dual antibody based ELISA that specifically identifies VLDL from LDL and HDL
ApoB100ApoC
VLDL Export
McCourt et al., 2015
0.016 0.03 0.1 0.30.75
0.8
0.85
0.9
0.95
1
[methionine], mM
arbi
trar
y un
its
0.033 0.1 2 4.50
0.2
0.4
0.6
0.8
1
1.2
[choline], mM
arbi
trar
y un
its
P = 0.7039
P = 0.0258
VLDL packagin
g and export
Oxidative Stress
ROS accumulation decreases hepatocyte function Fatty acid relative to no fatty acid for each treatment Increasing Choline concentration tended to decrease
ROS • 2 mM choline had lowest ROS
dL Met did not change ROS
Chandler et al., 2015
Hepatocyte Response Summary
Increasing dL MetDecreases endogenous Met regenerationDid not increase PEMT and does not change VLDL exportDid not change ROS
Increasing Choline Increases endogenous Met regenerationTended to decrease ROS accumulation Increased VLDL packaging
Chandler et al., 2015
Hepatocyte Response Summary
Suggests a biological priority for methyl donor use Whole-animal and cellular levelLack of interaction supports separate roles for Met
and Choline Increased NEFA may shift pathways of Met
regenerationCellular Met need can be met by dietary Met or by
endogenous regenerationMet regeneration requires methyl donation
Choline can provide the methyl groupChandler et al.,
2015
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