TGF-β1 calcium signaling in osteoblasts

✍ Scribed by Leon J. Nesti; E.J. Caterson; Wan-Ju Li; Richard Chang; Thane D. McCann; Jan B. Hoek; Rocky S. Tuan

• Book ID: 102300055
• Publisher: John Wiley and Sons
• Year: 2007
• Tongue: English
• Weight: 160 KB
• Volume: 101
• Category: Article
• ISSN: 0730-2312
• DOI: 10.1002/jcb.21180

✦ Synopsis

Abstract

Transforming growth factor‐β1 (TGF‐β1) action is known to be initiated by its binding to multiple cell surface receptors containing serine/threonine kinase domains that act to stimulate a cascade of signaling events in a variety of cell types. We have previously shown that TGF‐β1 and BMP‐2 treatment of primary human osteoblasts (HOBs) enhances cell‐substrate adhesion. In this report, we demonstrate that TGF‐β1 elicits a rapid, transient, and oscillatory rise in the intracellular Ca^2+^ concentration, [Ca^2+^]~i~, that is necessary for enhancement of cell adhesion in HOBs but does not alter the phosphorylation state of Smad proteins. This rise in [Ca^2+^]~i~ in HOB is not observed in the absence of extracellular calcium or when the cells are treated with the L‐type Ca^2+^ channel blocker, nifedipine, but is stimulated upon treatment with the L‐type Ca^2+^ channel agonist, Bay K 8644, or under high K^+^ conditions. The rise in [Ca^2+^]~i~ is severely attenuated after treatment of the cells with thapsigargin, a selective endoplasmic reticulum Ca^2+^ pump inhibitor. TGF‐β1 enhancement of HOB adhesion to tissue culture polystyrene is also inhibited in cells treated with nifedipine. These data suggest that intracellular Ca^2+^ signaling is an important second messenger of the TGF‐β1 signal transduction pathway in osteoblast function. J. Cell. Biochem. 101: 348–359, 2007. © 2007 Wiley‐Liss, Inc.