Niacin promotes adipogenesis by reducing production of anti-adipogenic PGF2α through suppression of C/EBPβ-activated COX-2 expression

Niacin is converted to NAD and NADP in tissues, whose products are involved in a number of cellular processes; and it is associated with the regulation of adipogenesis. In this study, we identified the molecular mechanism by which niacin promotes the adipogenesis in mouse 3T3-L1 cells. When the cells were cultured with niacin, the expression of adipogenic peroxisome proliferator-activated receptor gamma, CCAAT enhancer binding protein (C/EBP)alpha, and their target genes was enhanced concomitant with an increase in triglyceride storage. Moreover, niacin suppressed the expression of cyclooxygenase-2 and decreased the production of prostaglandin (PG) F-2 alpha in the early phase of adipogenesis, which PG suppresses the progression of adipogenesis via the PGF(2 alpha) receptor. Furthermore, niacin decreased the C/EBP beta level in the early phase of adipogenesis. These results indicate that niacin promoted adipogenesis by suppressing the production of the anti-adipogenic PGF(2 alpha) through down-regulation of C/EBP beta-activated cyclooxygenase-2 expression in adipocytes. (C) 2011 Elsevier Inc. All rights reserved.