TRANSFORMING GROWTH-FACTOR-BETA IS A SURVIVAL FACTOR FOR NEONATE CORTICAL-NEURONS - COINCIDENT EXPRESSION OF TYPE-I RECEPTORS IN DEVELOPINGCEREBRAL CORTICES

Transforming growth factor-beta (TGF-beta) is a multifunctional polype ptide which plays a crucial role in the regulation of cell proliferati on, differentiation, and organogenesis. In the present study, we inves tigated the expression of signaling receptors for TGF-beta in developi ng mice by in situ hybridization, revealing a significant difference i n the expression of TGF-beta type I and type II receptors. Unexpectedl y, the TGF-beta type I receptors were exclusively expressed without an y detectable expression of the TGF-beta type II receptors in developin g cerebral cortices. In primary cortical neurons, a neutralizing antib ody for TGF-beta significantly reduced the expression of bcl-2 and sub sequently induced neuronal cell death, indicating that TGF-beta functi ons as a survival factor for cortical neurons in vitro. Consistent wit h the result of in situ hybridization, the TGF-beta type I but not typ e II receptors were detected in primary cortical neurons by affinity c rosslink and RT-PCR analyses. The concomitant expression of TGF-beta 2 and the TGF-beta type I receptors in developing cerebral cortices sug gests that the TGF-beta signaling system plays a pivotal role in neuro nal differentiation and that unidentified components may be involved i n TGE-beta signaling in the development of the central nervous system. (C) 1996 Academic Press, Inc.