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Regulation of Osteogenic Expression of PGE2 by TGF-B1 in Mouse Calvarial Cells
Gliniak, C.M., Sweeney, W.M., Gupta, A.K., Gosain, A.K.
Case Western Reserve University / University Hospitals, Plastic Surgery Dept.
2010-03-31
Presenter: Christy Gliniak BS
Affidavit:
Director Name:
Author Category: Resident/Fellow
Presentation Category: Basic Science Research
Abstract Category: Craniomaxillofacial
Prostaglandin E2 (PGE2) plays an essential role in skeletal tissue development by stimulating bone formation and resorption through the replication and differentiation of osteoblasts. Transforming Growth Factor B1 (TGF-B1) has been shown to regulate the expression of Cox2, a key enzyme in PGE2 biosynthesis, in a variety of cell types. Since TGF-B1 is known to have a significant role in cranial suture fusion, this study investigates the effect of TGF-B1 on Cox-2 and PGE2 expression.
Primary cells of dura and sutural-osteoblasts were harvested from the Posterior Frontal (PF) and Sagittal areas of mouse calvaria and grown in culture. Cells were treated with TGF-B1 or SB431542, a specific inhibitor of TGF-B1 signaling pathway. Expression of Cox-2 mRNA and protein were determined by qPCR and Western blot. Cells were also transfected with TGF-B-receptor-1 specific siRNA (siRNA-TGF-BR1) and treated with TGF-B1. PGE2 expression was measured by ELISA in the culture supernatant.
TGF-B1 induces Cox-2 expression in both dura and osteoblasts by 6-10 fold and the induction is completely abrogated in the presence of SB431542. Cox-2 expression parallels the release of PGE2 in culture supernatant. The specificity of this induction is further confirmed by inhibited expression of PGE2 in cell medium from siRNA-TGF-BR1 treated cells. Addition of TGF-B1 to the siRNA-TGF-BR1 treated cells did not show any induction of PGE2.
The present study is the first to demonstrate TGF-B1 mediated regulation of Cox-2 in calvarial tissues. Regulation of prostaglandins via Cox-2 may be a critical link in the pathway leading to cranial suture development.
