Mechanisms of renal cell repair following acute toxicant injury

Exposure of the kidney to high concentrations of exogenous chemicals can result in proximal tubular dysfunction, leading to acute renal failure (ARF) that is reversible depending on the severity of injury. Sublethally-injured renal proximal tubular cells (RPTC) are thought to repair and regenerate tubular morphology and function through proliferation, migration, and differentiation, though the exact mechanisms involved in these processes are unknown. Primary cultures of RPTC exposed to the model nephrotoxicant S-(1,2-dichlorovinyl)-L-cysteine (DCVC) exhibit sustained inhibition of physiological functions and are unable to regenerate the monolayer following injury. L-Ascorbic acid-2-phosphate (AscP) was shown previously to promote the return of functions and monolayer regeneration in DCVC-injured RPTC, providing a model system for examining the mechanisms of repair and regeneration of chemically-injured RPTC. The goal of this dissertation was to determine the key factors and events involved in the repair and regeneration of DCVC-injured RPTC.; AscP is known to promote collagen production; therefore, the ability of DCVC-injured RPTC to synthesize and deposit collagen IV, the major tubular basement membrane component, was determined. Irreversible injury produced by DCVC exposure was associated with the inability of RPTC to deposit collagen IV. RPTC cultured in pharmacological concentrations of AscP repaired functions, regenerated the monolayer, and were able to maintain collagen IV deposition at control levels.; Since RPTC interact with collagen IV through collagen-binding integrins (CBI), the expression and localization of CBI in RPTC following injury by DCVC was determined. Flow cytometric analysis of RPTC showed minimal changes in CBI expression following sublethal injury. Confocal microscopy demonstrated the partial redistribution of CBI to the apical membrane of RPTC following DCVC exposure.; An important role has emerged for collagen IV in the mechanisms of RPTC repair following sublethal injury. AscP promotes cell repair and regeneration in injured RPTC, in part, through maintained deposition of collagen IV and the restoration of CBI-collagen IV interactions. Likewise, the direct addition of exogenous collagen IV promotes cell repair and the restoration of CBI-collagen IV interactions. This effect is specific for collagen IV, since other prominent ECM proteins do not stimulate RPTC repair. (Abstract shortened by UMI.)...