The role of XIAP during cold ischemia and kidney transplantation.

描述（由申请人提供）：肾移植是终末期肾病的首选治疗方法。移植后肾功能衰竭被称为延迟移植功能（DGF）。在美国，高达50%的原发性死亡供者肾移植发生DGF，并独立预测1年和5年肾移植存活率降低。长时间冷缺血（CI）是DGF的重要危险因素。在美国，捐赠肾脏的平均CI为24小时。当CI超过30小时时，DGF显著增加。当器官在移植前冷却至4℃时，CI发生，并与肾小管上皮细胞（RTEC）的凋亡有关。移植前供肾RTEC细胞凋亡预测移植后DGF的发生。我们发表的数据表明，CI 48小时导致caspase-3蛋白增加，RTEC细胞凋亡和刷状边界损伤（BBI）。哺乳动物的冬眠动物，如十三棱地松鼠，采用独特的保护方法，使它们能够在冬天忍受几天的CI。我们用冬眠的13纹地松鼠来发现我们可以在老鼠身上研究的新途径。我们的初步数据表明，冬眠的13行地松鼠即使在CBT为4C的情况下持续数天（远远超过人类和小鼠肾脏耐受的时间），也没有增加caspase-3或RTEC凋亡（Jani 2011, in press）。冬眠13行地松鼠的细胞凋亡保护作用与X-linked inhibitor of apoptosis protein （XIAP）的上调有关。因此，我们测量了小鼠和猪肾在CI作用下的XIAP。我们的初步数据表明，非冬眠小鼠和猪肾脏的CI与XIAP减少，capase -3和RTEC凋亡增加有关。该资助的一个具体目标是确定XIAP在ci诱导小鼠肾脏损伤的病理生理学中的作用。XIAP属于凋亡抑制蛋白（IAP）家族，其成员结合并抑制caspases 3、7和/或9。XIAP被丝氨酸蛋白酶HTRA2抑制，而HTRA2又可以被UCF-101化学抑制。本拨款的一个具体目标是确定CI在CI和肾移植期间对小鼠肾脏中XIAP蛋白表达的影响。特异性目的1研究XIAP上调（通过UCF-101）和下调（通过HTRA2）对RTEC细胞凋亡的影响。特异性目的2研究在肾移植前CI期间通过XIAP操作减少RTEC凋亡是否能改善移植后的移植物功能。

DESCRIPTION (provided by applicant): Kidney transplantation is the treatment of choice for End-Stage Renal Disease. Failure of a kidney to function after transplantation is referred to as Delayed Graft Function (DGF).DGF occurs in up to 50% of primary deceased-donor renal transplants in the US and independently predicts reduced 1- and 5-year kidney transplant survival. Prolonged cold ischemia (CI) is a significant risk factor for DGF. The average CI of donor kidneys in the US is 24 hours. DGF increases substantially when CI exceeds 30 hours. CI occurs when the organ is cooled to 4C prior to transplant, and is associated with apoptosis of renal tubular epithelial cells (RTEC). RTEC apoptosis in the donor kidney before transplant predicts the occurrence of DGF after transplant. Our published data indicates that CI of 48 hours results in increased caspase-3 protein, RTEC apoptosis and Brush Border Injury (BBI). Mammalian hibernators, such as the 13-lined ground squirrel, employ unique methods of protection that enable them to endure several days of CI during winter. We used hibernating 13-lined ground squirrels to discover novel pathways that we could study in mice. Our preliminary data indicates that hibernating 13-lined ground squirrels do not have increased caspase-3 or RTEC apoptosis despite enduring CI with a CBT of 4C for several days (far longer than that tolerable by human and mouse kidneys) (Jani 2011, in press). Protection from apoptosis in hibernating 13-lined ground squirrels is associated with upregulation of X-linked inhibitor of apoptosis protein (XIAP). This led us to measure XIAP in mice and pig kidneys subjected to CI. Our preliminary data indicates that CI of non-hibernating mouse and pig kidneys is associated with decreased XIAP, increased capsase-3 and RTEC apoptosis. A specific goal of this grant is to determine the role of XIAP in the pathophysiology of CI-induced injury in mouse kidneys. XIAP belongs to the Inhibitor of Apoptosis Protein (IAP) family, whose members bind and inhibit caspases 3, 7, and/or 9. XIAP is inhibited by a serine protease HTRA2, which in turn can be chemically inhibited by UCF-101. A specific goal of this grant is to determine the effect of CI on XIAP protein expression in mouse kidneys during CI and kidney transplantation. Specific Aim 1 investigates the effect of XIAP up-regulation (by UCF-101) and down- regulation (by HTRA2), on RTEC apoptosis. Specific Aim 2 investigates whether reducing RTEC apoptosis by manipulation of XIAP during CI before kidney transplant, improves graft function after transplant. PUBLIC HEALTH RELEVANCE: Kidney transplantation is the treatment of choice for End-Stage Renal Disease. Failure of a kidney transplant to function is referred to as Delayed Graft Function, which occurs in up to 50% of kidney transplants in the US and is a public health concern. This project investigates the role of X-liked inhibitor of apoptosis protein in the pathophysiology of Delayed Graft Function.