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KMID : 0578319950050010072
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Molecules and Cells
1995 Volume.5 No. 1 p.72 ~ p.76
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Requirement of Alkaline Cytoplasmic pH for HeLa Cell Adhesion to a Collagen Substratum
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Chun Jang-Soo
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Abstract
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Spreading of HeLa cells, a transformed human epithelial cell line, on a collagen substrntum is initiated by the activation of phospholipase A₂which produces arachidonic acid as a consequence of cell surface collagen receptor clustering. Production of arachidonic acid initiates spreading of cells by activating protein kinase C. This study examined Na^(+)/M^(+) antiport and cytoplasmic pH (pHi) in the activation phospholipase A₂and cell spreading. HeLa cells have an alkaline pHi which appears to be mediated by Na^(+)/H^(+) exchange. There was no difference in pHi between cells in suspension and cells spread on substratum. However, cell spreading was blocked either at acidic pHi or by inhibition of Na^(+)/H^(+) antiport indicating that alkaline pHi is required for cell spreading. Inhibition of alkalinization of pHi also blocked release of arachidonic acid in cells plated on collagen subsotum. The inhibition of cell spreading by blocking alkalinization of pHi was reversed by either exogenous arachidonic acid or protein kinase C activating phorbol ester. Thus, the results suggest that alkalinization of pHi by Na^(+)/H^(+) exchange is required for the activating of phospholipase A₂and to initiate spreading of HeLa cells on a collagen substratum.
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