Cux-1 and Cell Cycle Regulation in Kidney Development

描述（由申请人提供）：本提案的总体目标是确定Cux-1是否是Notch信号通路的下游效应者。Cux-1是果蝇基因Cut的小鼠同源物。哺乳动物切割蛋白在许多不同的组织中作为细胞周期依赖的转录抑制因子发挥作用。Cux-1在S期抑制细胞周期蛋白激酶抑制剂p21的表达，是控制G1-S转变的网络的一部分。Cux-1也抑制CKI p27，在转基因小鼠中Cux-1的异位表达导致p27表达异常下调导致多器官增生。虽然人们对Cux-1调控的靶点了解很多，但对Cux-1的上游调控机制知之甚少。在果蝇中，Cut作为Notch信号通路的下游效应体起作用。初步研究表明，Cux-1在表达构成性活性Notch受体的大鼠肾上皮细胞中表达上调，这与p27的表达降低有关。此外，免疫沉淀试验揭示了Cux-1与groucho同源物TLE-4之间的相互作用，TLE-4是一种与Notch信号已知效应物相互作用的共抑制因子。最后，最近的研究揭示了Cux-1和Notch通路组分在肾脏发育过程中的表达模式惊人的相似。这些结果表明，Cux-1是Notch信号通路的一个效应体。这些研究将验证Notch信号通路对Cux-1的调控在哺乳动物发育过程中是保守的，以及Cux-1与TLE蛋白相互作用调控p27基因表达的假设。具体目标是：1。确定Cux-1表达是否需要Notch信号。2. 评估TLE蛋白与Cux-1之间的相互作用。3. 确定Cux-1和Notch2在体内肾脏发育中的关系。4. 明确足细胞发育和肾形成过程中Cux-1、TLE-4和Notch信号之间的关系。这些研究将为研究细胞在发育过程中的增殖机制提供新的见解。

DESCRIPTION (provided by applicant): The overall aim of this proposal is to determine whether Cux-1 is a downstream effector of the Notch signaling pathway. Cux-1 is the murine homologue of the Drosophila gene Cut. Mammalian Cut proteins function as cell cycle-dependent transcriptional repressors in many different tissues. Cux-1 represses the expression of the cyclin kinase inhibitor p21 in S phase and is part of the network controlling G1-S transition. Cux-1 also represses the CKI p27, and ectopic expression of Cux-1 in transgenic mice results in multiorgan hyperplasia from the aberrant down regulation of p27 expression. While much has been learned about the targets of Cux-1 regulation, little is known about the upstream regulators of Cux-1. In Drosophila, Cut functions as a downstream effector of the Notch signaling pathway. Preliminary studies show that Cux-1 is upregulated in rat kidney epithelial cells expressing a constitutively active Notch receptor, and this is associated with decreased expression of p27. In addition, immunoprecipitation assays reveal an interaction between Cux-1 and the groucho homologue TLE-4, a co-repressor that interacts with known effectors of Notch signaling. Finally, recent studies reveal a striking similarity in expression pattern between Cux-1 and Notch pathway components during kidney development. These results suggest that Cux-1 functions as an effector of the Notch signaling pathway. The proposed studies will test the hypothesis that regulation of Cux-1 by the Notch signaling pathway is conserved during mammalian development and that Cux-1 interacts with TLE proteins to regulate p27 gene expression. The specific aims are: 1. Determine whether Notch signaling is required for Cux-1 expression. 2. Evaluate the interaction between TLE proteins and Cux-1. 3. Define the relationship between Cux-1 and Notch2 in kidney development in vivo. 4. Define the relationship between Cux-1, TLE-4, and Notch signaling during podocyte development and nephrogenesis. These studies will provide novel insights into the mechanisms of cell proliferation during development.