| Abstract: | Integrins are a superfamily of cell surface receptors involved in cell-cell and cell-matrix adhesion. Integrin-mediated interactions are involved in the regulation of numerous cellular functions such as fertilization, implantation, cell differentiation and migration during embryonic development, maintaining tissue architecture, blood clot formation and retraction programmed cell death, tumor growth and metastasis formation, lymphocyte homing and response of cells to mechanical stresses. This broad spectrum of activity is achieved by combining the ability to create mechanically functional junctions (cell-matrix and cell-cell) and signal-transducing capabilities. Osteoblasts and osteoclasts express specific integrin receptors and the pattern of expression varies depending on the stage of cell differentiation. Interactions of integrins with bone-matrix adhesive proteins are thought to be important for regulating the tissue integrity and may provide a local, responsive regulatory system of osteoblastic differentiation as well. Osteoclasts most likely attach to osteopontin exposed on the bone surface via the classic vitronectin receptor alpha v beta 3 and this binding may be crucial to their bone resorption activity. |
