Modulators of Mad family Function: MIx and mSin3A

描述(申请人提供)：原癌蛋白Myc的功能是 转录调节因子，在许多人类癌症中被解除调控。一种情结 蛋白质-蛋白质和蛋白质-DNA相互作用网络控制着Myc的活动。 MYC本身不起作用，但与Max形成异二聚体；Myc：Max 调节参与细胞分裂、生长和生长的基因的表达 新陈代谢。Max有许多蛋白质伙伴，包括Mad转录 抑制者。我们已经确定了一种MAX模拟产品MLX。与MAX一样，MLX与 疯狂的家庭成员压制转录。MLX还与一部小说互动 转录因子家族，蒙多家族。Mondo蛋白可能是 Myc.的功能类似物Mondo蛋白与MLX及Mondo：MLX相互作用 异源二聚体可以结合与Myc：Max相同的CACGTG E盒元件并激活 抄写。在果蝇中，dMondo和dMyc的功能相似 小路。与Myc：Max，Mondo：M1x的核定位相反 定位于细胞质。细胞质所需的两个新结构域 Mondo：MLX异源二聚体的定位：一个新的保守区 Mondo家族成员的N-末端和C-末端的保守结构域 Mondo和MLX蛋白的同源性。我们假设Mondoa：MLX起作用 与Myc：Max在控制细胞生长方面类似，但其核活动是 在细胞质隔离的严格控制下。此外，我们假设 Mondo：MLX从细胞质中释放并在细胞核中积聚 对细胞外信号的反应，这些信号影响到 在Mondo的N-末端的调控结构域。我们在此建议确定 与Mondoa相关的蛋白质：MLX(Aim 1)，执行结构功能 分析Mondo和MLX中的新结构域(Aim 2)，研究 Mondo的生物学功能：MLX(目标3)，并确定 触发Mondoa：MLX从细胞质中释放(目标4)。我们提出了一个 使用细胞生物学分析的多学科方法，全球转录 分析、生化纯化和一种新的反向双杂交系统。

DESCRIPTION (provided by applicant): The proto-oncoprotein Myc functions as a transcriptional regulator and is deregulated in many human cancers. A complex network of protein-protein and protein-DNA interactions controls Myc activity. Myc does not function on its own, but forms heterodimers with Max; Myc:Max regulates the expression of genes involved in cell division, growth and metabolism. Max has many protein partners including the Mad transcriptional repressors. We have identified a Max analog, Mlx. Like Max, Mlx interacts with Mad family members to repress transcription. Mlx also interacts with a novel family of transcription factors, the Mondo family. Mondo proteins may be functional analogs of Myc. Mondo proteins interact with Mlx and the Mondo:Mlx heterodimer can bind the same CACGTG E box element as Myc:Max and activate transcription. In Drosophila, dMondo and dMyc function in similar genetic pathways. In contrast to the nuclear localization of Myc:Max, Mondo:M1x localizes to the cytoplasm. Two novel domains are required the for cytoplasmic localization of Mondo:Mlx heterodimers: a novel conserved region in the N-terminus of the Mondo family members and a conserved domain in the C-terminus of both Mondo and Mlx proteins. We hypothesize that MondoA:Mlx functions similarly to Myc:Max in controlling cell growth, but its nuclear activity is under tight control by cytoplasmic sequestration. Furthermore, we hypothesize that Mondo:Mlx is released from the cytoplasm and accumulates in the nucleus in response to extracellular signals and that these signals impinge on the regulatory domain at the N-terminus of Mondo. We propose here to determine the proteins associated with MondoA:Mlx (Aim 1), perform structure-function analyses on the novel domains in Mondo and Mlx (Aim 2), investigate the biological function of Mondo:Mlx (Aim 3), and determine the signals that trigger MondoA:Mlx release from the cytoplasm (Aim 4). We propose a multidisciplinary approach using cell biological assays, global transcript analysis, biochemical purification and a novel reverse two-hybrid system.