The effect of pleiotrophin signaling on adipogenesis

Pleiotrophin (PTN) plays diverse roles in cell growth and differentiation. In this investigation, we demonstrate that PTN plays a negative role in adipogensis and that glycogen synthase kinase 3 beta (GSK-3 beta) and beta-catenin are involved in the regulation of PTN-mediated preadipocyte differentiation. Knocking down the expression of PTN using siRNA resulted in an increase in phospho-GSK-3 beta expression, and the accumulation of nuclear beta-catenin, which are critical downstream signaling proteins for both the PTN and Wnt signaling pathways. Our investigation suggests that there is a PTN/PI3K/AKT/GSK-3 beta/beta-catenin Signaling pathway, which cross-talks with the Wnt/Fz/GSK-3 beta/beta-catenin pathway and negatively regulates adipogenesis. (c) 2006 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.