转录因子ZFHX3类泛素化修饰及其在孕激素诱导乳腺发育中的作用和机制研究

The development of mammary gland is a complex process governed by a range of transcription factors and their post-transcriptional modifications induced by various hormones. The progesterone (Pg)-progesterone receptor (PR) signaling is particularly important for mammary gland development during pregnancy, regulating epithelial cell proliferation and differentiation and mammary gland side branching and alveologenesis. Our previous studies have demonstrated that the transcription factor zinc finger homeobox 3 (ZFHX3, also known as ATBF1 for AT motif binding factor 1) is essential for Pg to induce side-branching and lobuloalveolar formation in mammary glands, as Zfhx3 deletion severely attenuates these processes in mice. In addition, ZFHX3 is SUMOylated, and its SUMOylation alters its interactions with other proteins, its cellular distribution and stability. Based on our extensive preliminary studies including the ongoing analysis of how ZFHX3 is SUMOylated and de-SUMOylated, we plan to use in vitro and in vivo mammary gland differentiation models and a variety of methods to understand the role and mechanisms for ZFHX3 SUMOylation in mammary epithelial differentiation. 1) Dynamic status of SUMOylated Zfhx3 in mammary tissues at different times during pregnancy and its effect on mammary epithelial differentiation. 2) Effect of SUMOylation on the interactions of Zfhx3 with ER and PR and other proteins involved in mammary epithelial differentiation; and 3) Role of SUMOylated ZFHX3 in the transcriptional regulation of key genes involved in mammary gland development at pregnancy.

乳腺发育依赖于多种激素介导的转录因子及其翻译后修饰。孕激素是孕期乳腺发育的最主要信号，为孕期乳腺上皮分化、侧导管分枝和腺泡形成所必需。前期结果表明，孕激素信号依赖于转录因子ZFHX3发挥功能，Zfhx3基因敲除严重破坏孕激素诱导的小鼠乳腺侧导管分枝和腺泡形成。另外，ZFHX3发生SUMO化，影响其胞内定位、稳定性以及与其他蛋白的相互作用。但SUMO化是否影响ZFHX3和激素信号的相互作用及其对乳腺上皮分化的调控尚不清楚。本项目拟在前期工作以及正在研究的ZFHX3的SUMO化和去SUMO化机制基础上，利用体内外乳腺分化发育模型和各种方法，研究SUMO化ZFHX3对乳腺上皮分化的作用和机理：1）SUMO化ZFHX3在孕期发育乳腺组织中的状态和调控乳腺分化发育的功能；2）SUMO化对ZFHX3和ER、PR及其他蛋白相互作用的调控；3）ZFHX3如何调控乳腺发育关键基因的转录以及SUMO化的作用。

Zfhx3基因缺失对肿瘤形成和发育影响较大。同时，ZFHX3发生SUMO化，影响其胞内定位、稳定性及其与其他蛋白的相互作用。但SUMO化是否影响ZFHX3的功能以及内在机制尚不清楚。本项目在前期工作与正在研究的ZFHX3SUMO化和去SUMO化机制基础上，完成了以下工作：1）Zfhx3在孕激素信号调控乳腺发育中的功能与作用机制；2）Zfhx3在激素诱导乳腺和前列腺肿瘤中的功能与作用机制；3）ZFHX3复合物与染色质构象和组蛋白修饰的关系：4）ZFHX3发生SUMO化修饰过程的具体分子机制；5）ZFHX3 SUMO化修饰促进乳腺癌细胞增殖和成瘤；6）ZFHX3及其SUMO化修饰与DNA损伤修复的关系。这些工作的完成有利于阐明ZFHX3发生SMUO化的分子机制及其在肿瘤发生与组织发育中的作用。