DIFFERENTIAL GENE-EXPRESSION IN MIGRATING RENAL EPITHELIAL-CELLS AFTER WOUNDING

An in vitro model of wound healing was used to study cell migration th at is independent of proliferation during renal regeneration after acu te tubular necrosis. Monolayer cultures of high-density, quiescent ren al epithelial cells of the BSC-1 line were subjected to scrape woundin g and then Northern blot analysis was employed to identify genes that mediate cell migration. After wounding the monolayer, there is maximal induction of the immediate-early genes Egr-1, c-fos, NAK-1, and gro a t 1 hour followed by peak induction of connective tissue growth factor (CTGF) and c-myc at 4 hours. Message levels of urokinase-type plasmin ogen activator (u-PA) and its inhibitor (PAI-1) and heat shock protein (HSP)-70 are markedly raised 4-8 hours after wounding. Constitutive e xpression is repressed at 1 hour for transcripts that encode receptors for fibronectin (FN), epidermal growth factor, and hepatocyte growth factor (c-met, and the secreted proteins FN and osteopontin. Expressio n of genes encoding transforming growth factor (TGF)-beta 1 and -beta 2, retinoic acid receptor alpha, int-1, int-2, and gap junction protei n which can play a role in cell movement, appeared unchanged after wou nding. Differential expression of genes was a function of cell locatio n relative to the wound; NAK-1, PAI-1, and HSP-70 were induced or stim ulated only in cells at the wound edge, u-PA was stimulated in cells a way from the wound, and CTGF was induced in each of these populations suggesting that cell-to-cell communication may regulate gene expressio n after wounding. Adenosine diphosphate, a potent stimulator of cell m igration which enhances expression of u-PA and PAI-1 in nonwounded cul tures, additively stimulates these genes after wounding and may thereb y potentiate wound healing. Thus scrape wounding of renal epithelial c ells is followed by induction, stimulation, or repression of specific genes with distinct responses in different populations of cells. (C) 1 995 Wiley-Liss, Inc.