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E. F. Talarico, C. F. Marfurt, B. G. Kennedy, N. J. Mangini; Plasma Membrane Calcium-ATPase Isoform-Four Changes Distribution During Corneal Epithelial Wound Healing. Invest. Ophthalmol. Vis. Sci. 2008;49(13):3384.
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© ARVO (1962-2015); The Authors (2016-present)
Plasma Membrane Calcium-ATPase (PMCA) is an integral membrane protein essential to the control of intracellular Ca2+ concentration. In humans, four genes encode PMCA proteins termed PMCA1 - PMCA4. PMCA4 is the major PMCA isoform expressed in human corneal epithelium (CE); however, little is known about its role. The present work examined the distribution of PMCA4 during CE wound healing in a rabbit model.
Circular, 6 mm diameter corneal wounds were produced in the central CE of rabbits using the n-heptanol technique. The distribution of PMCA4 in CE was examined by immunohistochemical staining of frozen sections using PMCA4 isoform-specific antibody at 6-, 24-, 36- and 48 h post-injury. PMCA4 localization during reepithelialization was evaluated by calculating the percentage of corneal basal epithelial cells that demonstrated immunoreactivity (IR) along the apical versus basal membrane and within the cytoplasm.
PMCA4 IR in control corneas was observed in the plasma membrane of all cells and in all layers of CE, with a lack of IR along the basal epithelial cell membranes adjacent to the basal lamina. During the lag phase of wound healing (6h), PMCA4 IR was seen mostly in the apical plasma membranes of basal epithelial cells near the wound margin, with little IR in the basal plasma membranes. During the migration phase (24h), PMCA4 IR was found mostly on basal cell membranes adjacent to the basal lamina. At 6- and 24 h post-wounding, PMCA4 IR in the cytoplasm of basal epithelial cells was increased compared to controls. After wound closure (36 to 48 h), PMCA4 IR was again found primarily on the apical membrane of basal epithelial cells rather than on cell membranes adjacent to the basal lamina, and PMCA4 IR of the cytoplasm was similar to that of control corneas.
PMCA4 distribution in basal epithelial cell membranes changes during corneal epithelium wound healing. We suggest that PMCA4 redistribution is a factor in mediating calcium-regulated events associated with cell migration and adhesion in regenerating CE.
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