Intra-renal transfection of heat shock protein 90 alpha or beta (Hsp90α or Hsp90β) protects against ischemia/reperfusion injury.

Background. We previously reported that radicicol (Hsp90 inhibitor) induced a reduction in the renal blood flow and glomerular filtration rate, in part due to a reduction in urinary NO2/NO3 excretion, suggesting that Hsp90 regulates renal vascular tone in physiological conditions. However, there is a lack of information concerning Hsp90 alpha or Hsp90 beta role on eNOS activity and their association with acute kidney injury (AKI) characterized by an inadequate NO production. This study evaluated the effects of Hsp90 alpha or Hsp90 beta intra-renal transfection under ischemia/reperfusion (IR) injury. Methods. Uninephrectomized (Nx) rats were intra-renally transfected through injections with Hsp90 alpha or Hsp90 beta cloned into pcDNA3.1(+) or empty vector (EV) at 48 h before inducing IR, as indicated in the following groups: (i) Nx + sham, (ii) Nx + IR, (iii) Nx + IR + EV, (iv) Nx + IR + Hsp90 alpha and (v) Nx + IR + Hsp90 beta. After 24 h, physiological, histopathological, biochemical and molecular studies were performed. Results. IR-induced renal dysfunction, structural injury, tubular proliferation, the elevation of urinary Hsp72 and the reduction of urinary NO2/NO3 excretion. These alterations were associated with reduced eNOS-Hsp90 coupling and changes in the eNOS phosphorylation state mediated through a reduction in PKC alpha and increased Rho kinase expression. In contrast, intra-renal transfection of Hsp90 alpha or Hsp90 beta prevented IR injury that was associated with the restoration of eNOS-Hsp90 coupling, eNOS activating phosphorylation and PKC alpha and Rho kinase levels. Conclusions. Here we showed that eNOS-Hsp90 uncoupling plays a critical role in promoting NO reduction during IR. This effect was effectively reversed through Hsp90 alpha or Hsp90 beta intra-renal transfection, suggesting their implication in regulating NO/eNOS pathway and the renal vascular tone.