The Integrin αvβ5 Is Expressed on Avian Osteoclast Precursors and Regulated by Retinoic Acid

Open Access
Publisher Website
Google Scholar
Abstract
Osteoclasts arise by proliferation, differentiation, and subsequent fusion of marrow‐derived precursors, all processes requiring attachment to matrix. Integrins are important mediators of cell‐matrix recognition and bone is rich in proteins containing the Arg‐Gly‐Asp motif, recognized primarily by αv integrins. Thus, we determined if avian osteoclast precursors express integrins capable of mediating initial attachment to matrix proteins. Early, marrow‐derived osteoclast precursors, when first isolated, contain no detectable αvβ3, but express an αv integrin with an 80 kDa associated β subunit. Immunoprecipitation with an antibody raised against the conserved β5 cytoplasmic tail sequence indicates the the αv associated the integrin is αvβ5. Retinoic acid is a resorptive steroid, and its exposure to early osteoclast precursors prompts a time‐ and dose‐dependent decrease in αvβ5 expression, while simultaneously stimulating αvβ3 expression. Northern analysis reveals that retinoic acid decreases β5 steady‐state mRNA, nontranscriptionally, without altering that of αv. The finding αvβ5 expression decreases under the influence of retinoic acid, an osteoclastogenic steroid, while those of αvβ3 rise, suggests that these closely related integrins play separate and complementary roles during osteoclast differentiation.

This publication has 43 references indexed in Scilit: