Effects of leptin on lipid metabolism and gene expression of differentiation-associated growth factors and transcription factors during differentiation and maturation of 3T3-L1 preadipocytes = 지방대사와 지방전세포주의 분화관련 유전자에의 렙틴의 영향

Abstract

The present study was designed to determine the effects of leptin on lipid metabolism and gene expression during differentiation and maturation of the 3T3-L1 murine preadipocyte. The preadipocytes were induced to differentiate in a growth medium containing 10% calf serum and a hormonal cocktail for 2 days. The cells were next allowed to maturate for 14 days in the growth medium supplemented with 10 μg/ml insulin or 500 ng/ml insulin-like growth factor (IGF)-I in the absence or presence of supplemented leptin. Leptin, at a dose of 5 to 500 ng/ml, had no effect on proliferation of undifferentiated 3T3-L1 cells. However, leptin suppressed the insulin- or IGF-I-stimulated lipid accumulation and enhanced the release of glycerol, a measure of lipolysis, in a dose-dependent manner during and after the maturation of the cell. Moreover, leptin at a dose of 50 ng/ml inhibited IGF-I gene expression during the entire differentiation and maturation and also peroxisome proliferator activated receptor (PPAR)-γ expression during late maturation as monitored by semi-quantitative reverse transcription-polymerase chain reaction. However, leptin exerted no effect on the expression of transforming growth factor-β, CCAT/enhancer binding protein-α and PPAR-δ. Taken together, results suggest the anti-lipogenic and lipolytic effects of leptin in differentiating and mature adipocytes may have been partly mediated by suppressing the expression of PPAR-γ and IGF-I genes.