Terminal Differentiation of the Renal Epithelium

描述（由申请人提供）：终末肾单位分化的分子基础，即未成熟肾上皮细胞退出细胞周期并表达生理功能的过程，仍然不清楚。终末肾单位分化失败导致肾发育不良、膀胱形成和癌症。因此，更好地了解调控肾细胞分化的转录框架具有重要的临床意义。肿瘤抑制蛋白p53是调节细胞生长、分化、衰老和凋亡的转录因子家族的成员，并且在发育期间和响应于应激的细胞命运决定中起关键作用。在之前的资助期间，我们证明了p53及其同源物p73作为终末肾单位分化所需基因上游的主转录调节因子; p53/p73的这种功能是通过与其他发育调节转录因子的合作以及共激活子或共抑制子的招募来实现的。与此作用一致，p53 -/-小鼠表现出终末肾单位分化的缺陷，这可以通过p53的肾特异性缺失/失活来再现。这一竞争性资助更新的总体目标是阐明调控p53激活和承诺的机制，以促进发育中肾脏的终末分化命运。我们将使用各种体内遗传和生化方法，连同在体外器官培养系统，以测试模型中，Mdm 2和其他负调节p53发挥严格的时空控制p53在终末肾单位分化。我们建议，p53是优先需要执行分化程序的输尿管芽细胞系，这一功能是精心策划和破译不同的乙酰化和磷酸化盒差异影响基因表达模式，从而细胞的命运。研究p53在发育过程中是如何被调控的，以及p53是如何执行其分化功能的，是理解器官发生的遗传控制的重要基础步骤。这些研究具有重要的临床意义，因为肾脏发育异常是婴儿和儿童慢性肾衰竭的主要原因。公共卫生相关性：该提案解决了肾脏发育中的关键步骤，该步骤与控制未成熟肾细胞向分化和功能转变的细胞和分子事件有关。肾脏发育的中止（即，先天性畸形）占需要透析和移植的婴儿和儿童慢性肾衰竭病例的40%。了解肾上皮细胞如何从不成熟转变为更分化的命运，应该为重要疾病的新治疗提供见解，包括肾畸形，癌症和急性肾损伤的恢复。

DESCRIPTION (provided by applicant): The molecular basis of terminal nephron differentiation, the process by which immature renal epithelial cells exit the cell cycle and express physiological functions, remains obscure. Failure of terminal nephron differentiation results in renal dysplasia, cystogenesis and cancer. Thus, a better understanding of the transcriptional framework which regulates renal cell differentiation is of great clinical significance. The tumor suppressor protein, p53, is a member of a family of transcription factors that regulate cellular growth, differentiation, senescence and apoptosis, and play a key role in cell fate determination during development and in response to stress. During the previous funding period, we demonstrated that p53 and its homologue p73 act as master transcriptional regulators upstream of genes required for terminal nephron differentiation; this function of p53/p73 is accomplished via cooperation with other developmentally regulated transcription factors and recruitment of co-activators or co-repressors. Consistent with this role, p53 -/- mice exhibit defects in terminal nephron differentiation, which can be reproduced by kidney-specific deletion/inactivation of p53. The overall goal of this competing grant renewal is to elucidate the mechanisms governing p53 activation and commitment to promote the terminal differentiation fate in the developing kidney. We will use a variety of in vivo genetic and biochemical approaches, together with an in vitro organ culture system, to test a model in which Mdm2 and other negative regulators of p53 exert strict spatiotemporal control on p53 during terminal nephron differentiation. We propose that p53 is preferentially required to execute a differentiation program in the ureteric bud cell lineage, and that this function is orchestrated and deciphered by distinct acetylation and phosphorylation cassettes which differentially influence gene expression patterns and thus cell fate. Investigations of how p53 is regulated during development and how p53 executes its differentiation functions are important basic steps toward understanding the genetic control of organogenesis. The proposed studies have important clinical implications as abnormal renal development is the leading cause of chronic renal failure in infants and children. PUBLIC HEALTH RELEVANCE: This proposal addresses a critical step in kidney development related to the cellular and molecular events that control the transition of immature kidney cells to become differentiated and functional. Abnormalities of kidney development (i.e., congenital malformations) account for up to 40% of cases of chronic kidney failure in infants and children requiring dialysis and transplantation. Understanding how kidney epithelial cells transition from an immature to a more differentiated fate should provide insights into novel treatments of important diseases including kidney malformations, cancer, and recovery from acute kidney injury.