JNK/AP-1信号通路介导的FoxK2对肾脏发育调控的分子机制研究

Kidney is an important excretory organ and kidney correlative diseases always been a substantial threaten of health. Elucidating the kidney developmental process and how does this organ exercise its physiological function, always been an important and intriguing research area of biological and medical science. Our previous study has shown specific spatial expression pattern in kidney development and highly conserved in evolution of FoxK2. Zebrafish embryos display developmental defects in response to FoxK2 depletion using genetic modification tools TALENs indicating the novel role for FoxK2 renal development. We have also found the forkhead transcription factor FoxK2 promotes AP-1-mediated transcriptional regulation. JNK/AP-1 signaling is one of the key regulatory of kidney development for promoting the nephron progenitor cells proliferation, suggesting the possibility of a novel JNK/AP-1- FoxK2 regulatory pathway in renal development. In this study, we intend to clarify the regulatory mechanism of FoxK2 towards AP-1, verify the JNK/AP-1- FoxK2 signal pathway，and identify further FoxK2 function in zebrafish and genetically engineered mouse mode. This study would promote the understanding of molecular mechanism in renal development， providing new ideas and approaches for treatment of renal development disorders.

肾脏是人体的重要排泄器官，与肾脏相关的各种疾病是对人类健康最重大的威胁之一。阐明肾发育分子机制一直是医学研究的重要领域。我们前期研究发现转录因子FoxK2在肾发育过程中存在时间表达特异性，其氨基酸序列在进化上高度保守，运用TALENs介导的FoxK2敲除斑马鱼模型，发现胚胎发育明显延缓，提示FoxK2可能具有调控肾脏发育新功能；首次发现FoxK2促进AP-1信号介导的下游靶基因转录，已知JNK/AP-1对肾单位祖细胞增殖起中心调控作用，是肾发育关键调控通路之一。提示FoxK2可能通过JNK/AP-1通路影响肾脏发育。本研究旨在阐明FoxK2与AP-1的相互作用；体内外验证FoxK2通过JNK/AP-1信号通路对肾单位祖细胞增殖的影响；运用斑马鱼和基因工程小鼠模型研究FoxK2对肾发育的调控作用。本研究将有助于进一步理解肾脏发育的分子机制,为肾脏发育异常导致的肾脏疾病提供新的治疗思路与途径。

FoxK2是转录因子Fox家族的成员之一, 大多数 Fox 转录因子和其他的转录因子与核受体形成复合物参与了肺、肌肉、肾脏及中枢神经系统等器官发育，特别是在调节细胞增殖、分化和细胞存活之间的动态平衡发挥重要作用。Foxk2对肾脏发育的调控尚不清楚。本项目发现FoxK2氨基酸序列在进化上高度保守，我们分析了Foxk2在斑马鱼胚胎早期发育过程中的表达模式以及小鼠肾脏发育不同时期的表达水平，发现在小鼠肾发育过程中存在时间表达特异性，出生后表达急剧下降。运用TALENs介导的FoxK2敲除斑马鱼模型，发现胚胎发育明显延缓，并发现过表达Foxk2会促进斑马鱼胚胎背部化。小鼠帽状间充质细胞中敲低Foxk2，显著抑制抑制小鼠帽状间充质细胞增殖。同时，敲低Foxk2会降低c-Jun的表达，回补c-Jun能够部分恢复Foxk2敲低引起的帽状间充质细胞增殖。并且Foxk2蛋白能够与c-Jun蛋白直接相互作用。这些结果揭示了Foxk2通过调控c-Jun促进小鼠帽状间充质细胞（MK3）增殖。本研究将有助于进一步理解肾脏发育的分子调控机制。