Dexamethasone‐dependent expression of β^1–24 corticotropin stimulated adenylate cyclase during adipose conversion of 3T3‐F442A cells

Abstract

When 3T3-F442A preadipocytes were grown in culture media supplemented with corticosteroid poor fetal calf serum and insulin they differentiated into adipocytes. Glycerophosphate dehydrogenase, a marker of terminal differentiation, developed a 600-fold increase of activity whereas the adenylate cyclase system remained unresponsive to the synthetic ACTH(1-24) analog. In contrast, 3T3-F442A adipocytes, differentiated in the presence of dexamethasone, exhibited an adenylate cyclase activity which was stimulated 4-fold by ACTH(1-24). The stimulation of the adenylate cyclase activity by GTPyS remained unchanged (about 20-25-fold) suggesting that the G regulatory coupling protein was not functionally modified by dexamethasone. Binding studies with t25I-ACTH revealed that specific cellular binding could be evidenced in dexamethasone-treated cells while control adipocytes did not exhibit any specific binding of 125I-ACTH. These findings lend support to the hypothesis that the setting off of this ACTH responsiveness in 3T3-F442A cells is regulated by dexamethasone after cells are committed to adipose differentiation.

Pterostilbene Inhibits Lipogenic Activity similar to Resveratrol or Caffeine but Differently Modulates Lipolysis in Adipocytes

“…To this aim, preliminary tests were performed on murine 3T3‐F442A cells that slightly differ from 3T3‐L1 in their requirements for adipocyte differentiation. Adipogenesis of 3T3‐F442A cells is only insulin dependent (Fève and Pairault, ), while 3T3‐L1 cells also need priming with isobutylmethylxanthine and dexamethasone. 3T3‐F442A preadipocytes accumulated triacylglycerols when continuously stimulated by 50‐nM insulin for eight days (positive control of adipogenesis set at 100%).…”

The Aging Fat Cell

“…Corticosteroids exert divergent effects of preadipocyte lines, depressing the capacity for adipoconversion in 3T3‐F442A and ob 17, while stimulating it in 3T3‐L1 and TA1 151–153 . One explanation for this could be the pleiotypic action of these hormones, involving the modulation of the affinity and/or receptor concentrations of a variety of heterologous hormone and growth factor receptors 154 . When dexamethasone is added to the culture medium of TA1 cells, it induces an early accumulation of various mRNAs seemingly specific for adipoconversion, as if the hormone increased the expression of a regulating factor required for the activation of a set of genes concerned in the differentiation process 152 .…”