Department of Nephrology, The Second Xiangya Hospital at Central South University, Changsha, China.
Department of Cellular Biology and Anatomy, Medical College of Georgia at Augusta University and Charlie Norwood Veterans Affairs Medical Center, Augusta, Georgia.
J Am Soc Nephrol. 2020 May;31(5):1050-1065. doi: 10.1681/ASN.2019101060. Epub 2020 Apr 14.
Kidney injury associated with cold storage is a determinant of delayed graft function and the long-term outcome of transplanted kidneys, but the underlying mechanism remains elusive. We previously reported a role of protein kinase C- (PKC) in renal tubular injury during cisplatin nephrotoxicity and albumin-associated kidney injury, but whether PKC is involved in ischemic or transplantation-associated kidney injury is unknown.
To investigate PKC's potential role in injury during cold storage-associated transplantation, we incubated rat kidney proximal tubule cells in University of Wisconsin (UW) solution at 4°C for cold storage, returning them to normal culture medium at 37°C for rewarming. We also stored kidneys from donor mice in cold UW solution for various durations, followed by transplantation into syngeneic recipient mice.
We observed PKC activation in both and models of cold-storage rewarming or transplantation. In the mouse model, PKC was activated and accumulated in mitochondria, where it mediated phosphorylation of a mitochondrial fission protein, dynamin-related protein 1 (Drp1), at serine 616. Drp1 activation resulted in mitochondrial fission or fragmentation, accompanied by mitochondrial damage and tubular cell death. Deficiency of PKC in donor kidney ameliorated Drp1 phosphorylation, mitochondrial damage, tubular cell death, and kidney injury during cold storage-associated transplantation. PKC deficiency also improved the repair and function of the renal graft as a life-supporting kidney. An inhibitor of PKC, V1-1, protected kidneys against cold storage-associated transplantation injury.
These results indicate that PKC is a key mediator of mitochondrial damage and renal tubular injury in cold storage-associated transplantation and may be an effective therapeutic target for improving renal transplant outcomes.
冷保存相关的肾损伤是延迟移植物功能和移植肾脏长期预后的决定因素，但潜在机制仍难以捉摸。我们之前报道了蛋白激酶 C（PKC）在顺铂肾毒性和白蛋白相关肾损伤过程中肾小管损伤中的作用，但 PKC 是否参与缺血性或移植相关的肾损伤尚不清楚。
为了研究 PKC 在冷保存相关移植过程中损伤的潜在作用，我们将大鼠肾近端小管细胞在威斯康星大学（UW）溶液中于 4°C 进行冷保存，然后在 37°C 的正常培养基中进行复温。我们还将供体小鼠的肾脏在冷 UW 溶液中储存不同的时间，然后移植到同基因受体小鼠中。
我们观察到在 和 冷储存复温或移植模型中均存在 PKC 激活。在小鼠模型中，PKC 被激活并在线粒体中积累，在那里它介导线粒体分裂蛋白 dynamin 相关蛋白 1（Drp1）在丝氨酸 616 处的磷酸化。Drp1 激活导致线粒体分裂或碎片化，伴随着线粒体损伤和肾小管细胞死亡。供体肾脏中 PKC 的缺失改善了 Drp1 磷酸化、线粒体损伤、肾小管细胞死亡和冷保存相关移植中的肾损伤。PKC 缺失也改善了作为生命支持肾脏的肾移植物的修复和功能。PKC 的抑制剂 V1-1 可保护肾脏免受冷保存相关的移植损伤。
这些结果表明 PKC 是冷保存相关移植中线粒体损伤和肾小管损伤的关键介质，可能是改善肾移植结果的有效治疗靶点。
