Ubiquitin Proteasome System, Mitochondria, and Renal Cold Storage

Project: Research


  • Nirmala Parajuli (PI)


Many end stage kidney disease patients die while waiting for a kidney transplant because there are too few viable donor kidneys. The majority of donor kidneys come from deceased donors and are routinely stored in cold storage solutions prior to transplantation. Unfortunately, extended cold storage induces renal damage, which will lead to poor outcomes after transplantation. Understanding the pathways leading to renal damage during cold storage (CS) may uncover new preventive strategies to reduce damage and improve transplant outcomes. Our laboratory has shown that renal CS leads to increased reactive oxygen species (ROS) generation, mitochondrial dysfunction, and renal damage. However, the extent of damage that occurs following transplantation or identification of the precise mechanisms involved with damage are not known. ROS mediated damage can lead to activation of the ubiquitin proteasome system, a proteolytic pathway for clearance. Our preliminary data suggests that CS plus transplantation increases proteasome activity and degradation of mitochondrial complex I proteins, in a ROS dependent manner. In addition, early studies show that adding Bortezomib, a clinically relevant proteasome inhibitor, to the cold storage solution increases mitochondrial function and prevents complex I degradation and renal cell death. Therefore, we hypothesize that following CS +/- transplantation; mitochondrial ROS-induced active proteasome is recruited to the mitochondria, where it leads to proteolysis of key mitochondrial complex proteins, contributing to mitochondrial and renal dysfunction. Thus, proteasomal inhibition during renal CS will preserve mitochondrial and organ function in the transplanted kidneys. We will test this hypothesis, using renal cells and a rat renal transplantation model in two specific aims: Aim 1 will determine the role of proteasome activity to mitochondrial/renal dysfunction during CS+/-transplantation. Studies will examine the effect as well as the mechanism of action of Bortezomib using in vitro and in vivo rat models. Aim 2 will identify whether Complex I (NDUFS3 subunit) is a mitochondrial target for ROS-induced proteasomal degradation following CS +/- transplantation using the in vitro and in vivo models. The findings will establish the novel interaction between proteasome, mitochondria, and ROS; which could lead to improved transplant outcomes and less cardiovascular disease in patients with end stage kidney disease.
Award amount$231,000.00
Award date01/01/2016
Program typeScientist Development Grant
Award ID16SDG27600026
Effective start/end date01/01/201603/01/2020