beta 1-Integrin-mediated glioma cell adhesion and free radical-induced apoptosis are regulated by binding to a C-terminal domain of PG-M/versican. |
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Authors: | Yaojiong Wu Liwen Chen Peng-Sheng Zheng Burton B Yang |
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Institution: | Sunnybrook and Women's College Health Sciences Centre and the Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario M4N 3M5, Canada. |
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Abstract: | Integrins are cell-surface glycoproteins that mediate cell activities, including tissue morphogenesis, development, immune response, and cancer, through interaction with extracellular proteins. Here we report a novel means by which integrin signaling and functions are regulated. In pull-down assays and immunoprecipitation, beta(1)-integrin bound to the C-terminal domain of PG-M/versican, an extracellular chondroitin sulfate proteoglycan. This was confirmed by cell-surface binding assays. Binding was calcium- and manganese-dependent. Upon native gel electrophoresis, beta(1)-integrin comigrated with the C-terminal domain of PG-M/versican. The interaction of beta(1)-integrin with the C-terminal domain of PG-M/versican activated focal adhesion kinase, enhanced integrin expression, and promoted cell adhesion. As a result, cells expressing the C-terminal domain of PG-M/versican were resistant to free radical-induced apoptosis. As the PG-M/versican peptide used in this study does not contain the RGD consensus-binding motif for integrins, the mechanism of the observed binding represents an entirely new function. |
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