1?,25(OH)2D3 Regulation of integrin expression is substrate dependent

✍ Scribed by Raz, P. ;Lohmann, C. H. ;Turner, J. ;Wang, L. ;Poythress, N. ;Blanchard, C. ;Boyan, B. D. ;Schwartz, Z.

• Publisher: John Wiley and Sons
• Year: 2004
• Tongue: English
• Weight: 366 KB
• Volume: 71A
• Category: Article
• ISSN: 0021-9304
• DOI: 10.1002/jbm.a.30134

✦ Synopsis

Abstract

Osteoblasts are attachment‐dependent cells that interact with their surface through integrin‐mediated mechanisms. Their differentiation is regulated by 1,25‐dihydroxyvitamin D3 [1α,25(OH)~2~D~3~] and is affected by substrate chemistry and microtopography, suggesting that 1α,25(OH)~2~D~3~ may regulate integrin expression in a surface‐specific manner. To test this hypothesis, osteoblast‐like human MG63 cells were grown on tissue culture plastic and on grit‐blasted and acid‐etched titanium disks with a complex microtopography to induce osteoblast differentiation. Expression of α~2~, α~5~, α~v~, β~1~, and β~3~ integrins were quantified by real‐time polymerase chain reaction (PCR) as a function of time in culture and treatment with 1α,25(OH)~2~D~3~. Results were correlated with expression of osteocalcin, a marker of a differentiated osteoblast. Osteocalcin mRNA increased with time and 1α,25(OH)~2~D~3~ treatment and these changes were greater in cultures on the titanium disks. Integrin expression varied with time in culture and this was also surface dependent. At each time point, β~1~ and α~2~ mRNAs were greater on titanium than on plastic, whereas α~5~ expression was reduced and α~v~,β~3~ expression was unaffected. 1α,25(OH)~2~D~3~ increased β~1~ mRNA on both surfaces at all time points, but it increased α~2~ expression only in 8‐d cultures. 1α,25(OH)~2~D~3~ caused reduced α~5~ expression only in cultures grown on plastic for 8 d, and had no effect on either α~v~ or β~3~ expression regardless of surface. These results show that integrin expression in human osteoblast‐like cells is differentially modulated by 1α,25(OH)~2~D~3~ in a time‐dependent manner that is sensitive to the surface on which the cells are grown. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res 71A: 217–225, 2004