Selective changes in enzymes of the sn-glycerol 3-phosphate and dihydroxyacetone-phosphate pathways of triacylglycerol biosynthesis during differentiation of 3T3-L1 preadipocytes.
Enzyme activities of the sn-glycerol 3-phosphate (glycerol-P) and of the dihydroxyacetone-phosphte (DHAP) pathway of glycerolipid biosynthesis were investigated during the differentiation of 3T3-L1 preadipocytes into adipocytes. Total particulate glycerol-P and DHAP acyltransferase activities increased 70- and 30-fold, respectively, during differentiation induced with methylisobutylxanthine and dexamethasone. The N-ethylmaleimide-sensitive (microsomal) glycerol-P and DHAP acyltransferase activities were virtually undetectable in nondifferentiated cells, and increased in parallel over 70-fold during differentiation. These and several kinetic observations are consistent with the induction of a single microsomal enzyme having dual activity. During differentiaion, the N-ethylmaleimide-resistant DHAP acyltransferase activity increased 10-fold, suggesting the presence of at least two DHAP acyltransferase isoenzymes. Qualitatively similar changes in microsomal glycerol-P and DHAP acyltransferase activities were observed when cell differentiation was induced with insulin or with insulin plus dexamethasone and methylisobutylxanthine. Acyl-DHAP oxidoreductase (EC 1.1.1.101) specific activity increased only 3- to 5-fold during adipocyte differentiation. Alkyl-DHAP synthase activity was not detected. These data demonstrate that selective changes in enzyme activities of the gycerol-P pathways of glycerolipid synthesis occur during the differentiation of 3T3-L1 preadipocytes.
D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D000217:Acyltransferases / Q000378:metabolism; D000273:Adipose Tissue / Q000166:cytology / Q000201:enzymology*; D000818:Animals; D002454:Cell Differentiation; D002478:Cells, Cultured; D003907:Dexamethasone / Q000494:pharmacology; D004099:Dihydroxyacetone Phosphate / Q000378:metabolism*; D005992:Glycerol-3-Phosphate O-Acyltransferase / Q000378:metabolism; D005994:Glycerophosphates / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D008297:Male; D051381:Rats; D013401:Sugar Alcohol Dehydrogenases / Q000378:metabolism; D014280:Triglycerides / Q000096:biosynthesis*; D014306:Trioses / Q000378:metabolism*
D005994:Glycerophosphates; D014280:Triglycerides; D014306:Trioses; D004099:Dihydroxyacetone Phosphate; D003907:Dexamethasone; D013401:Sugar Alcohol Dehydrogenases; C022312:acylglycerone-phosphate reductase; D000217:Acyltransferases; D005992:Glycerol-3-Phosphate O-Acyltransferase; C020051:glycerone-phosphate O-acyltransferase; D015056:1-Methyl-3-isobutylxanthine