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移植物功能延迟（DGF）JGF发生在美国高达50%的原发性死亡供体肾移植中，并且独立地预测1年和5年肾移植存活率降低。长期冷缺血（CI）是DGF的重要危险因素。在美国，供体肾脏的平均CI为24小时。当CI超过30小时时，DGF显著增加。CI发生在器官在移植前冷却至4 ℃时，并与肾小管上皮细胞（RTEC）的凋亡有关。移植前供肾中RTEC凋亡可预测移植后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凋亡和刷状缘损伤（BBI）。哺乳动物冬眠动物，如13线地松鼠，采用独特的保护方法，使他们能够忍受数天的CI在冬季。我们使用冬眠的13线地松鼠来发现我们可以在小鼠中研究的新途径。我们的初步数据表明，冬眠的13线地松鼠没有增加半胱天冬酶-3或RTEC细胞凋亡，尽管在4C的CBT下持续CI数天（远远长于人类和小鼠肾脏的耐受时间）（Jani 2011，出版中）。冬眠13线地松鼠的细胞凋亡保护与X连锁凋亡抑制蛋白（XIAP）的上调有关。这使我们测量了遭受CI的小鼠和猪肾脏中的XIAP。我们的初步数据表明，非冬眠小鼠和猪肾脏的CI与XIAP降低，Capsase-3和RTEC凋亡增加有关。这项资助的一个具体目标是确定XIAP在CI诱导的小鼠肾脏损伤的病理生理学中的作用。XIAP属于凋亡蛋白抑制剂（IAP）家族，其成员结合并抑制半胱天冬酶3、7和/或9。XIAP被丝氨酸蛋白酶HTRA 2抑制，而HTRA 2又可以被UCF-101化学抑制。这项资助的一个具体目标是确定CI和肾移植期间CI对小鼠肾脏中XIAP蛋白表达的影响。具体目的1研究XIAP上调（通过UCF-101）和下调（通过HTRA 2）对RTEC细胞凋亡的影响。具体目标2研究在肾移植前CI期间通过操纵XIAP减少RTEC凋亡是否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.