Elevated serum creatine phosphokinase in choline-deficient humans: mechanistic studies in C2C12 mouse myoblasts.
BACKGROUND
Choline is a required nutrient, and humans deprived of choline develop liver damage.


OBJECTIVE
This study examined the effect of choline deficiency on muscle cells and the release of creatine phosphokinase (CPK) as a sequela of that deficiency.


METHODS
Four men were fed diets containing adequate and deficient amounts of choline, and serum was collected at intervals for measurement of CPK. C2C12 mouse myoblasts were cultured in a defined medium containing 0 or 70 micromol choline/L for up to 96 h, and CPK was measured in the media; choline and metabolites were measured in cells. Apoptosis was assessed by using terminal deoxynucleotidyl transferase-mediated dUTP-biotin end labeling and activated caspase-3 immunohistochemistry. Cell fragility in response to hypo-osmotic stress was also assessed.


RESULTS
Three of 4 humans fed a choline-deficient diet had significantly elevated serum CPK activity derived from skeletal muscle (up to 66-fold; P < 0.01) that resolved when choline was restored to their diets. Cells grown in choline-deficient medium for 72 h leaked 3.5-fold more CPK than did cells grown in medium with 70 micromol choline/L (control medium; P < 0.01). Apoptosis was induced in cells grown in choline-deficient medium. Phosphatidylcholine concentrations were diminished in choline-deficient cells (to 43% of concentrations in control cells at 72 h; P < 0.01), as were concentrations of intracellular choline, phosphocholine, and glycerophosphocholine. Cells grown in choline-deficient medium had greater membrane osmotic fragility than did cells grown in control medium.


CONCLUSIONS
Choline deficiency results in diminished concentrations of membrane phosphatidylcholine in myocytes, which makes them more fragile and results in increased leakage of CPK from cells. Serum CPK may be a useful clinical marker for choline deficiency in humans.
da Costa
Kerry-Ann
KA
Department of Nutrition, School of Public Health and School of Medicine, University of North Carolina at Chapel Hill, 27599, USA.
Badea
Mihaela
M
Fischer
Leslie M
LM
Zeisel
Steven H
SH
D000328:Adult; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D015415:Biomarkers / Q000097:blood; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D002460:Cell Line; D002796:Choline Deficiency / Q000201:enzymology*; D003402:Creatine Kinase / Q000097:blood* / Q000378:metabolism; D003470:Culture Media; D053938:DNA Fragmentation; D006801:Humans; D007150:Immunohistochemistry; D020287:In Situ Nick-End Labeling; D008099:Liver / Q000473:pathology; D008297:Male; D051379:Mice; D008875:Middle Aged; D032448:Myoblasts, Skeletal / Q000201:enzymology* / Q000378:metabolism; D009996:Osmotic Fragility
D015415:Biomarkers; D003470:Culture Media; D003402:Creatine Kinase; C505407:CASP3 protein, human; C505409:Casp3 protein, mouse; D053148:Caspase 3; D020169:Caspases