The role of p53 pro‐apoptotic target, PERP, induces mitochondrial permeability and apoptosis in hypoxic renal cells

Abstract

PERP, a direct target of p53, has lately been implicated in apoptosis, and we reported earlier a p53‐dependent upregulation of PERP in proximal tubular epithelia subsequent to ischemia/reperfusion injury (IRI); nonetheless, the role of PERP in IRI is unknown. To test our hypothesis that PERP alters mitochondrial membrane permeability (MMP) to induce apoptosis following renal IRI, we developed renal tubular epithelial cell lines (LLCPK1) stably overexpressing PERP (P‐Epi) or control vector (C‐Epi) and subjected to 4 hour (hr) hypoxia in a glucose‐free buffer followed by 1hr normoxia with normal medium replacement. By 1hr post‐injury, the mitochondrial membrane potential is significantly altered in P‐Epi cells compared to C‐Epi or uninjured cells (p< 0.001; n=3) as analyzed by flow cytometry with JC‐1 probing. In addition, AIF and cytochrome c were released from mitochondria earlier by 3hrs post‐injury in P‐Epi cells compared to C‐Epi cells. Further, the number of P‐Epi cells undergoing apoptosis by 3hrs post‐injury was higher compared to control cells (p< 0.05; n=3). Thus we conclude, upregluation of PERP accelerates the release pro‐apoptotic molecules by altering MMP after IRI in renal tubular epithelia. Targeting a p53 downstream molecule rather than p53 per se may offer a specific therapeutic strategy to inhibit p53‐mediated apoptosis in acute kidney injury. Support by Univ Nebraska Med Cntr and NKF Nebraska.