Fibromodulin Expression in Folliculostellate Cells and Pericytes Is Promoted by TGF? Signaling in Rat Anterior Pituitary Gland.

ABSTRACT: Fibromodulin belongs to the family of small leucine-rich proteoglycans (SLRPs), an active component of extracellular matrix. It directly binds collagens to promote fibrillogenesis and also binds transforming growth factor-beta (TGF?) to antagonize its actions. Our previous studies of rat anterior pituitary gland revealed that fibromodulin is expressed in folliculostellate cells and pericytes. Although our recent study showed that TGF?2 secreted from folliculostellate cells induces collagen synthesis in pericytes, the involvement of fibromodulin in TGF?2-mediated collagen regulation has not been studied. The present study examined the effect of TGF?2 on fibromodulin synthesis in rat anterior pituitary gland. In situ hybridization for TGF? receptor II and immunohistological techniques revealed the presence of TGF? receptor II in folliculostellate cells and pericytes. To confirm canonical TGF? intracellular signaling, Smad2 immunocytochemistry was performed. Nuclear translocation of Smad2 was observed in folliculostellate cells and pericytes after TGF?2 treatment. TGF?2 strongly enhanced fibromodulin mRNA and protein expressions, and TGF?2-induced mRNA expression was completely blocked by TGF? receptor I inhibitor (SB431542). These results suggest that folliculostellate cells and pericytes exhibit canonical TGF?2 signaling, which is associated with fibromodulin production. Thus, this is the first report to show that TGF? signaling regulates the endogenous TGF? antagonist fibromodulin in the gland.

SUBMITTER: Syaidah R 

PROVIDER: S-EPMC5263227 | biostudies-literature | 2016 Dec

REPOSITORIES: biostudies-literature