IMPAIRMENT OF INTEGRIN-MEDIATED CELL-MATRIX ADHESION IN OXIDANT-STRESSED PC12 CELLS

Oxidants are believed to play an important and complex role in neurona l injury and death in the aging process and various neurode generative diseases. We studied the effect of oxidative stress on integrin-media ted cell-extracellular matrix (ECM) interactions using the PC12 neuron al cell line. In assays in which attachment was measured between 30 an d 90 min, addition of hydrogen peroxide (H2O2) to the attachment mediu m resulted in a dose-dependent inhibition of initial cell attachment t o collagen. Addition of H2O2 also caused previously attached cells to detach from collagen. The inhibition by H2O2 was specific for integrin -mediated adhesion, since attachment to substrata coated with non-ECM molecules was much less affected. Exposure of cells to H2O2 resulted i n a rapid and profound reduction of intracellular ATP, accompanied by only a slight increase in intracellular free Ca2+ concentration ([Ca2](i)). Treatment of cells with the microfilament-disrupting agent, cyt ochalasin B, like that with H2O2, inhibited cell adhesion to collagen. We propose that integrin-mediated cell adhesion, which requires inter actions between cytoplasmic portions of integrin subunits and cytoskel etal microfilaments, is impaired by oxidative stress as a result of th e depletion of intracellular ATP and that such depletion is an early e vent in the process of oxidant-induced neuronal injury.