Involvement of ezrin in cold storage preservation injury in renal proximal tubule epithelial cells: Possible structural and signaling roles

Abstract

Renal transplantation is the treatment of choice for patients with end‐stage renal disease. Preservation injury is caused by ischemia/reperfusion and hypothermia during cold storage, which leads to early graft loss and delayed graft function. Advancements in organ preservation are limited by our understanding of basic root mechanisms that cause this injury. We hypothesize that sub‐lamellar cytoskeletal protein failure is involved and studied this in isolated rabbit renal proximal tubules and epithelial cells. Tubules cold stored in UW solution released ezrin from cytoskeletal actin attachments. Ezrin phosphorylation at T567 and Y353 decreased with progressive cold storage ischemia, which controls both ezrin binding to the cytoskeleton and survival signaling through Akt, respectively. Tubule epithelial cell death at reperfusion after cold storage ischemia was almost exclusively by apoptosis (annexin‐V FACS analysis). Transfection of primary renal epithelial cells with wild‐type mammalian ezrin cDNA increased survival and viability after cold storage ischemia and reperfusion and increased Akt phosphorylation (IHC). Conversely, inhibition of ezrin expression with specific siRNA duplexes decreased cell survival and viability. In conclusion, inactivation of ezrin during preservation may cause renal preservation injury by altering membrane structure and by reducing survival signaling.