Lipogenic and mitogenic effects of insulin during conversion of Ob17 cells to adipose-like cells.
Chronic exposure to insulin of confluent cells of a preadipocyte clonal line (Ob17) leads to an acceleration of their development into adipose cells. The short-term effects of insulin have been examined by the stimulation of [14C] alpha-aminoisobutyrate uptake and the long-term effects by the increase in the activity levels of several lipogenic enzymes and in the intracellular triacylglycerol content. These metabolic effects of insulin occur within a physiological range of concentrations (EC50 congruent to 1 nM). As compared to insulin, dose-response curves obtained with proinsulin on these parameters show at least a 10-fold decrease in sensitivity of the cells. In contrast, the growth-promoting effects of both insulin and proinsulin occur at supraphysiological concentrations (EC50 greater than 300 nM). This mitogenic response is likely mediated through binding to receptors of insulin-like growth factors. Our data demonstrate that long-term effects of insulin on lipid synthesis can be dissociated from its effect on cell growth. Therefore the Ob17 cell line should be a useful model to study the role of insulin in the regulation of lipid synthesis in adipose cells.
D000273:Adipose Tissue / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D000621:Aminoisobutyric Acids / Q000378:metabolism; D000818:Animals; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D004247:DNA / Q000096:biosynthesis; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases / Q000032:analysis; D007328:Insulin / Q000378:metabolism / Q000494:pharmacology*; D008055:Lipids / Q000096:biosynthesis*; D008297:Male; D051379:Mice; D008934:Mitogens / Q000494:pharmacology*; D011384:Proinsulin / Q000494:pharmacology
D000621:Aminoisobutyric Acids; D007328:Insulin; D008055:Lipids; D008934:Mitogens; D004247:DNA; D011384:Proinsulin; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases