In:
Annals of the New York Academy of Sciences, Wiley, Vol. 961, No. 1 ( 2002-06), p. 178-182
Abstract:
A bstract : The osteoactive factor, transforming growth factor β1 (TGF‐β1), influences osteoblast activity and bone function. We recently characterized a Smad‐independent TGF‐β1‐induced Ca 2+ signal in human osteoblasts (HOB) and demonstrated its importance in cell adhesion. Here, we further elucidate the role of the TGF‐β1 Ca 2+ signal in the mechanics of HOB adhesion. Osteoblast interaction with fibronectin (FN) through α5β1 integrin is principally responsible for osteoblast‐substrate adhesion. Our results show that the TGF‐β1 intracellular Ca 2+ signal is responsible, in part, for stimulation of α5 integrin expression, but not β1 integrin or FN expression. Increased α5 integrin protein and mRNA expression was seen as early as 12 h after TGF‐β1 treatment, but was inhibited by cotreatment with nifedipine, a Ca 2+ channel blocker. TGF‐β1 increased both FN and β1 integrin protein production within 48 h, independent of nifedipine cotreatment. Immunofluorescence observations revealed that TGF‐β1 increased α5 integrin staining, clustering, and colocalization with the actin cytoskeleton, effects that were blocked by nifedipine. The TGF‐β1 Ca 2+ signal, a pathway crucial for HOB adhesion, enhances α5 integrin expression, focal contact formation, and cytoskeleton reorganization. These early events are necessary for osteoblast adhesion; thus they determine the fate of the cell and ultimately affect bone function.
Type of Medium:
Online Resource
ISSN:
0077-8923
,
1749-6632
DOI:
10.1111/nyas.2002.961.issue-1
DOI:
10.1111/j.1749-6632.2002.tb03078.x
Language:
English
Publisher:
Wiley
Publication Date:
2002
detail.hit.zdb_id:
2834079-6
detail.hit.zdb_id:
211003-9
detail.hit.zdb_id:
2071584-5
SSG:
11
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