Suppression of 11b‐Hydroxysteroid Dehydrogenase Type 1 with RNA Interference Substantially Attenuates 3T3‐L1 Adipogenesis

Abstract

Overexpression of 11b‐hydroxysteroid dehydrogenase type 1 (11b‐HSD1) in adipose tissue leads to obesity in mice. We hypothesized that endogenous 11b‐HSD1 played a significant functional role in adipogenesis. Stable transfection of 3T3‐L1 cells with small hairpin RNA (shRNA), compared to a nucleotide‐substituted control, silenced 11b‐HSD1 expression and substantially attenuated the accumulation of lipid droplets and the expression of adipogenesis marker genes induced by a mixture containing either corticosterone or dexamethasone. 11b‐HSD1 silencing significantly elevated the concentration of 11‐dehydrocorticosterone in the culture supernatant, but did not affect the levels of corticosterone or dexamethasone, measured by LC‐MS/MS. 11b‐HSD1 silencing significantly attenuated the translocation of glucocorticoid receptors to the nucleus and reduced the number of cells entering the S phase in response to glucocorticoids (13 ± 1% vs. 30 ± 1% in control, n=5, P<0.05), a critical event in the initiation of adipogenesis. 11b‐HSD1 shRNA delivered by lentiviral vectors after the induction of differentiation reduced 11b‐HSD1 expression, but did not affect the further progression of adipogenesis. Our results established a functional and stage‐dependent role of 11b‐HSD1 in the initiation of 3T3‐L1 adipogenesis, and provided new insights into the development of obesity and related diseases.