Kidney ischemia-reperfusion regulates expression and distribution of tubulin subunits, beta-actin and rho GTPases in proximal tubules.

Ischemic injury is characterized by a loss of cell polarity and a release of proximal tubule epithelial cells resulting from cytoskeletal reorganization. This study used a reversible unilateral renal ischemia-reperfusion model to investigate the expression and distribution of cytoskeletal components and Rho GTPases at protein and mRNA levels in proximal tubule fractions. Ischemia strongly increased beta-actin and alpha-tubulin expressions that were predominantly found in nuclear fractions. Rho GTPases and caveolin-1 expression were upregulated by ischemia and were enriched mainly in Triton-soluble membranes. Rac1 expression was stimulated in the soluble fractions during reperfusion. Rho GTPases mRNA levels were similarly regulated by ischemia-reperfusion suggesting that changes in their expressions could occur at gene or mRNA levels. ERM protein expression and distribution were unaffected by ischemia-reperfusion. Together, these data show that renal ischemia-reperfusion induced expression and redistribution of actin and microtubule cytoskeleton components in addition to Rho GTPases in proximal tubules, suggesting that they participate in an adaptive response to cellular lesions.