Inhibition of preadipocyte differentiation by myostatin treatment in 3T3-L1 cultures

Myostatin, a new TGF-beta family member, is known as a muscle growth inhibi tor, but its role in adipocyte development has not been studied. To test th e role of Myostatin in 3T3-L1 preadipocyte differentiation, we treated cult ured 3T3-L1 preadipocytes with Myostatin dissolved in 0.1% trifluoroacetic acid (TFA) during differentiation after they had become confluent. Myostati n treatment significantly decreased glycerol-3-phosphate dehydrogenase (GPD H) activity and oil Red-O staining compared to controls that did not receiv e Myostatin. Western blot analysis showed that the expression levels of CCA AT-enhancer binding protein a! (C/EBP alpha) and peroxisome proliferator-ac tivated receptor gamma (PPAR gamma) were significantly decreased by Myostat in treatment (P < 0.05). However, the expression of C/EBP <beta> was not si gnificantly changed by the treatment (P > 0.05). From RT-PCR result, the re lative level of leptin mRNA in Myostatin-treated cells was not significantl y different (P > 0.1) from the level in cells without Myostatin treatment. Our data show that Myostatin, a secreted protein from muscle, inhibits prea dipocyte differentiation in 3T3-L1 cells, which is mediated, in part, by al tered regulation of C/EBP a! and PPAR gamma. (C) 2001 Academic Press.