Structure and Mechanism in intracellular Notch signaling

描述（由申请人提供）：在人类和其他多细胞生物中，具有不同细胞类型的复杂组织必须由统一的前体细胞群形成。细胞分化在从单个细胞到成熟生物体的发育过程中，以及在成人干细胞中产生和替换分化细胞的过程中都是至关重要的。失去对分化的控制可能导致癌症。决定细胞命运的一个途径是“Notch”信号通路，这是一种细胞间的通讯途径，它在邻近细胞之间传递信息（通过一种叫做Notch的细胞表面受体蛋白），并在细胞内处理这些信息，根据需要调整细胞命运。我们正在研究Notch信号的定量和结构机制。我们希望了解信号接收细胞内的Notch通路蛋白如何控制命运。我们正在研究两个不同的Notch信号过程，每一个都由不同的细胞调节剂（Deltex和CSL）控制。Deltex、CSL、Notch受体和其他效应器的热力学、生化和高分辨率结构分析将用于促进对这些细胞命运决定背后的分子相互作用的理解。我们将确定Deltex如何结合Notch，如何修饰Notch（通过泛素化），以及哪些受体蛋白与哪些Deltex蛋白配对。研究将揭示Notch对CSL的二价识别是如何增加结合强度的，它是如何变弹性地开启该转录因子的，以及人类病毒是如何利用这一途径的。我们将通过果蝇的基因研究和培养细胞的转录分析来测试我们发现的功能意义。我们将利用结构基因组学联盟（多伦多大学）的管道来增加可用于生物物理和生化分析的Notch蛋白的数量。总之，这些研究将提供对Notch信号的理解，它将原子结构与生物体内的定量机制和功能联系起来。我们的研究是为了更好地了解Notch信号对人类健康很重要，因为Notch通路的缺陷会导致各种形式的人类癌症和发育畸形，并可能最终有助于这些疾病的治疗。我们的研究对于理解由Notch信号维持的干细胞生物学也很重要。

DESCRIPTION (provided by applicant): In humans and other multicellular organisms, complex tissues with different cell types must be formed from a uniform population of precursor cells. Cellular differentiation is critical in the development of a mature organism from a single cell, and in generating and replacing differentiated cells from stem cells in adults. Loss of control of differentiation can result in cancer. One pathway by which cell fate is determined is the "Notch" signaling pathway, a cell-cell communication pathway that relays information between neighboring cells (through a cell surface receptor protein called Notch) and processes this information inside the cell to tailor cell fate as needed. We are investigating the quantitative and structural mechanisms of Notch signaling. We wish to understand how Notch pathway proteins inside the signal-receiving cell control fate. We are studying two distinct Notch signaling processes, each controlled by a distinct cellular regulator (Deltex and CSL). Thermodynamic, biochemical, and high resolution structural analysis of the Deltex, CSL, the Notch receptor, and other effectors will be used to advance understanding of the molecular interactions underlying these cell fate decisions. We will determine how Deltex binds Notch, how it modifies Notch (via ubiquitination), and which receptor proteins pair with which Deltex proteins. Studies will reveal how bivalent recognition of CSL by Notch couples to increase binding strength, and how it allosterically turns this transcription factor on, and how a human virus exploits this pathway. We will test the functional significance of our findings through genetic studies in the fruit fly and transcription assays in cultured cells. We will take advantage of a Structural Genomics Consortium pipeline (University of Toronto) to increase the number of Notch proteins available for biophysical and biochemical analysis. Together, these studies will provide an understanding of Notch signaling that connects atomic structure to quantitative mechanism and function in the organism. Our research to better understand Notch signaling is important to human health, since defects in the Notch pathway lead to various forms of human cancer and to developmental malformities, and may ultimately contribute to treatment of these conditions. Our research is also important for understanding stem cells biology, which is maintained by Notch signaling.