Cyclin-dependent Kinase Inhibitor in Acute Renal Failure

描述（由申请人提供）：我们的长期目标是预防/治疗急性肾损伤。我们使用顺铂毒性作为肾损伤模型，体外使用培养的小鼠肾近端小管细胞，体内使用野生型和转基因小鼠。我们已经确定抑制细胞周期相关酶，细胞周期蛋白依赖性激酶-2 (Cdk2)，在体外保护细胞毒性，并保护体内由顺铂引起的肾损伤。基于这些发现，我们开发了两种转基因小鼠品系，由于特异性cdk2抑制，可抵抗顺铂诱导的急性肾损伤。我们发现细胞死亡的几种途径依赖于Cdk2活性，并有助于顺铂的细胞毒性。我们假设由顺铂激活并依赖于Cdk2激酶活性的细胞死亡可能可以通过交叉途径而不是平行途径来解释。现在我们发现，在对顺铂的反应中，Cdk2磷酸化了两种蛋白，p21和Bcl xL，这两种蛋白直接或间接地影响细胞死亡途径。在我们的第一个具体目标中，我们将研究这些蛋白质是否提供细胞周期和细胞死亡的交叉点。我们假设抑制Cdk2将是一种有效的短期和长期预防AKI的策略。我们最近开发的转基因小鼠，诱导p21或DN-Cdk2的表达保护顺铂肾毒性，证实了这一假设的前半部分。我们假设的后半部分将在第二个特定目标中得到解决，这将确定Cdk2抑制是否仅仅延迟肾毒性，以及Cdk2抑制和顺铂暴露是否会对肾脏恢复产生长期影响。

DESCRIPTION (provided by applicant): Our long-term goal is to prevent/treat acute kidney injury. We are using cisplatin toxicity as a model of renal injury, in vitro using cultured mouse kidney proximal tubule cells, and in vivo using wild-type and transgenic mice. We have established that inhibition of a cell cycle-associated enzyme, cyclin-dependent kinase-2 (Cdk2), protect from cytotoxicity in vitro and protects from kidney injury in vivo caused by cisplatin administration. Based on these findings, we developed two transgenic mouse strains resistant to cisplatin-induced acute renal injury because of specific cdk2 inhibition. We found that several pathways of cell death were dependent on Cdk2 activity and contribute to cisplatin cytotoxicity. We hypothesize that cell death activated by cisplatin and dependent on Cdk2 kinase activity can likely be explained by intersecting rather than parallel pathways. Now we find that in response to cisplatin, Cdk2 phosphorylates two proteins, p21 and Bcl xL, that directly and indirectly could have effects on cell death pathways. In our first specific aim we will investigate whether these proteins provide the intersections of cell cycle and cell death. We hypothesize that Cdk2 inhibition would be an effective short- and long-term strategy to prevent AKI. Our recently developed transgenic mice in which induced expression of either p21 or DN-Cdk2 protected from cisplatin nephrotoxicity confirmed the first half of this hypothesis. The second half of our hypothesis will be addressed in this second specific aim, which will determine whether Cdk2inhibition merely delays nephrotoxicity and whether Cdk2 inhibition and cisplatin exposure causes longer-term effects on kidney recovery. PUBLIC HEALTH RELEVANCE: Acute kidney injury (AKI) is a common disorder affecting up to 5% of hospitalized patients. Despite our increased understanding of the incidence and consequences of AKI, morbidity and mortality associated with this syndrome in critically ill patients has remained above 50%. AKI is an independent risk factor in the setting of multi organ failure leading to death and disability. The financial costs of AKI are estimated to be 8 billion dollars per year, or about $130,000 per life-year saved. It is unlikely that this high mortality and associated cost will be reduced until we understand the cellular and molecular mechanisms of cell injury and recovery. We found that cell cycle enzyme inhibitors will totally protect kidney cells in vitro from cisplatin cytotoxicity and significantly diminish morphologic and functional AKI in vivo. We have developed transgenic mice that are resistant to AKI. The mechanism of protection and its use in vivo will be investigated. Our proposal will lead to the development of agents that can be used to prevent AKI, which will directly impact patient care and well-being.