title: The effect of triiodothyronine on fatty acid synthetase activity and content in differentiating ob17 preadipocytes.
abstract: The effect of triiodothyronine on the activity and amount of the key lipogenic enzyme fatty acid synthetase was studied in differentiating preadipocyte cells (ob17) isolated from ob/ob mouse epididymal fat pad. In the presence of physiological concentrations of insulin, the acquisition of adipose morphology was accompanied by a parallel increase (10--15-fold) in synthetase specific activity and radioimmunoassayable amount relative to soluble cellular proteins. Inclusion of T3 at confluence significantly enhanced synthetase activity and content, with a maximum of 1.5--2-fold above controls at the physiological 1.5 nM concentration, whether insulin is present or not. During adipose conversion, T3 increased the development of enzyme activity and after a longer lag period, the accumulation of the synthetase. Our results suggest that the stimulating effect of T3 upon synthetase activity could involve as a first step the activation of preexisting inactive synthetase molecules and as a second one an increased accumulation of activable synthetase. After longer culture periods, inactive radioimmunoassayable synthetase accumulated.
mesh_terms: D000273:Adipose Tissue / Q000187:drug effects / Q000201:enzymology / Q000502:physiology*; D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects; D002478:Cells, Cultured; D064429:Fatty Acid Synthases / Q000302:isolation & purification / Q000378:metabolism*; D008297:Male; D051379:Mice; D008820:Mice, Obese; D008970:Molecular Weight; D011863:Radioimmunoassay; D051381:Rats; D011919:Rats, Inbred Strains; D014284:Triiodothyronine / Q000494:pharmacology*
chemical_list: D014284:Triiodothyronine; D064429:Fatty Acid Synthases