1,2-sn-Diacylglycerol accumulates in choline-deficient liver

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Abstract
Choline deficiency is associated with triacylglycerol accumulation in the liver, and is the only nutritional state known to trigger hepatic cancer spontaneously. In two different experiments, rats were pair-fed for 6 weeks with control (0.2% choline), or choline-deficient (CD) (0.002% choline) diets. Hepatic choline and phosphocholine declined in CD animals to 54% and 16% of control levels, respectively. In control livers, 1,2-sn-diacylglycerol (1,2-sn-DAG) concentration was (in nmol/g wet wt) 144 (± 25; mean ± SE); while in CD livers it was 792 (± 140) in the first experiment. In the second experiment the values were 375 (± 26) and 1147 (± 74), respectively. 1,2-sn-DAG, a precursor of triacylglycerol, is an endogenous activator of protein kinase C (PKC). PKC is the presumed site of action of the tumor-promoting phorbol esters. We suggest that the 1,2-sn-DAG accumulating in CD liver could bind PKC, altering its activity, and thus contribute to the carcinogenic effect of CD diets