GLUCOSE-TRANSPORTER-1 EXPRESSION IS ENHANCED DURING CORNEAL EPITHELIAL WOUND REPAIR

Corneal epithelial wound healing involves a number of metabolically de manding processes such as cell migration and proliferation. The energy for those processes is known to be provided by glycolysis. Thus, it w as hypothesized that migrating epithelium would require high levels of glucose to provide a substrate for glycolysis. It is well established that glucose is transported into virtually all mammalian cells by the facilitated glucose transport protein, glucose transporter (GLUT). We sought to investigate the expression of one of the isoforms of glucos e transporter, GLUT1, in corneal epithelium after epithelial debrideme nt in the rat. Three-millimeter debridement wounds were made on centra l rat cornea and allowed to heal from 1 hr to 21 days. To quantitate c hanges in GLUT1 mRNA and protein levels, whole corneal epithelium was harvested and analysed by reverse transcription-polymerase chain react ion, northern blot, and western blot analysis. GLUT1 protein localizat ion was also observed immunohistochemically. Expression of GLUT1 prote in rapidly increased following wounding and was 2.4-fold higher than c ontrol at 4 hr post debridement. GLUT1 protein levels continued to inc rease even after epithelial wound closure (24 hr) and peaked at 2 days post debridement, 5.8-fold higher than control. The increase in GLUT1 protein levels coincided with enhanced GLUT1 mRNA levels (3.7-fold hi gher than control at 4 hr post debridement). Immunofluorescence micros copy showed increased binding of anti-GLUT1 concentrated in the membra nes of the basal cells from limbus-to-limbus until 24 hr post wounding . After 24 hr, binding remained enhanced in the wound area, while bind ing to the limbal basal cells returned to the control level. In conclu sion, the expression of GLUT1 mRNA and protein are rapidly enhanced af ter wounding. This may allow the increased transport of glucose, provi ding the metabolic energy necessary for cell migration and proliferati on. (C) 1996 Academic Press Limited