A MOLECULAR MECHANISM OF INTEGRIN REGULATION FROM BONE-CELLS STIMULATED BY ORTHODONTIC FORCES

The purpose of this paper is to discuss a molecular mechanism in the s ignal transduction pathways of the regulation of integrin genes taking place in bone cells as a result of orthodontic or mechanical stimulat ion. Human osteosarcoma (HOS) TE-85 cells were cultured in Dulbecco's modified Eagle's medium (DMEM)/F-12 and grown to confluency in Flexerc ell type I dishes and orthodontic forces were applied to the cells via an intermittent strain of 3 cycles/minute using the Flexercell Strain Unit System for periods of 15 and 30 minutes, 2 and 24 hours and 3 da ys. Antibodies against beta(l) and alpha(v) integrins were immunolocal ized in strained and unstrained cultures. Total RNA was extracted and cDNA probes were used to measure at various mRNA expression of beta(1) (1.2 kb) and alpha(v) (1.1 kb) integrins. A cDNA probe for cyclophyli n (750 b) was used for controls of gene expression. Results showed tha t mechanical stimulation caused a reorganization of integrin distribut ion in comparison with non-stimulated controls. mRNA for beta(l) expre ssion showed a marked increase at 30 minutes and 3 days, while mRNA le vels for alpha(v) did not change with strain. The selective expression of integrins mRNA is indicative of a specific gene regulation by mech anical stimulation in the cells studied.