ABSTRACT
Astrocytes, the most abundant glia in the central nervous system, modulate neuronal survival and function. Astrocytic functions are mediated by synthesis and secretion of wide ranges of polypeptides through mechanism [s] poorly understood. Among these, TGF beta s are synthesized and released by the astrocytes. In this study, the involvement of Wnt signaling pathway on the synthesis of TGF beta s by the astrocyte was investigated. Cultured rat astrocytes were therefore treated either with Wnt3a [20ng/ml] alone for 24 hours or in combination with sFRP-1 [400 ng/ml] for a further 24 hours. Cells were then harvested and examined for the expression of TGF beta s and the Wnt target gene, cyclin D1. In this study, we were able to show that 1] treatment Wnt3a alone for 24 hours induced the expressions of TGF beta s and cyclin D1; 2] The effect of Wnt was inhibited by pre-treatment with sFRP-1, that is, sFRP-1 pre-treatment significantly blocked the Wnt-induced expressions of TGF beta s and cyclin D1. This study therefore provides the first evidence for the involvement of Wnt signaling pathway in the synthesis of TGF beta proteins by cortical rat astrocytes