LRRC4通过D domain与ERK相互作用调控ERK核转位抑制脑胶质瘤细胞的增殖和迁移

Leucine-rich repeat C4 (LRRC4) has been colned and confirmed as a tumor suppressor for glioma . Our previous studies indicatied that LRRC4 inhibited the glioma cells proliferation and invision by several signaling pathways, such as ERK/MAPK. Combined with our previous data and "scansite" analysis software, we found that LRRC4 is most likely to contain a "D domain" which can bind to ERK.By gaining the professional acknowledge, we concluded that the protein with "D domain" can interact with the CD domain of ERK throug their D domains, which then regulate the ERK nuclear translocation and the expression of its downstream transcription factor. At the same time, ERK can also phosphorylates the protein containing D domain . Therefore, we provide hypothesis that LRRC4 may be interact with ERK through its D domain to regulate ERK activity and nuclear translocation, and the expression of downstream transcript factors of ERK. Meanwhile, LRRC4 may achieve precise own activity regulation by ERK phosphorylation, so as to exert LRRC4 inhibitory function.In short, our project will explore the interaction between LRRC4 and ERK and their functional domain of the interaction. By studying, we will further to elucidate the molecular mechnism of LRRC4 as a tumor suppressor genes, which helps in clarifying the glioma development mechanism.

LRRC4是申请人所在实验室自主克隆的脑胶质瘤抑瘤基因，通过ERK/MAPK等多条信号通路抑制胶质瘤细胞生长和侵袭。在前期研究工作的基础上，通过复习文献，并结合生物信息学分析，发现LRRC4含有与ERK结合的D domain。研究表明，含有D domain的蛋白均可以通过D domain与ERK的CD domain结合，调控ERK的核转位及其下游转录因子的表达。同时ERK也可磷酸化含D domain的蛋白。因此，我们大胆推测，LRRC4极有可能通过D domian与ERK结合，调控ERK活化和核转位。同时LRRC4也可能被ERK磷酸化，达到对自身活性的精确调控，进而发挥其抑瘤功能。总之，本课题旨在探究LRRC4与ERK间的相互作用关系及相互作用的结构基础，进一步明确LRRC4发挥抑瘤作用的分子机制，为脑胶质瘤的发生发展提供极具优势的理论和实验依据。

LRRC4（Leucine-rich repeat-containing protein 4），又名NGL-2（Netrin-G ligand -2），是我室克隆的一个抑瘤基因，定位于染色体的7q31-32，是富亮氨酸重复序列（LRR，Leucine-rich repeat）蛋白超家族成员之一。前期研究表明，LRRC4通过 ERK/MAPK 等多条信号通路抑制胶质瘤细胞生长和侵袭。本研究进一步证实， LRRC4通过D domain与ERK的 CD domain直接存在相互作用。LRRC4通过D domain与ERK1/2结合并将ERK1/2锚定于胞浆；ERK通过CD domian与LRRC4结合，并定位于胞浆。LRRC4能够抑制胞浆以及胞核中ERK1/2的磷酸化水平；缺失D domain后，LRRC4对ERK1/2磷酸化的抑制作用减弱。免疫共沉淀进一步证实，LRRC4能够竞争性的抑制MEK1/2与ERK1/2的结合，进而抑制MEK1/2对ERK1/2的磷酸化激活。同时，LRRC4通过D domain影响ERK1/2对下游靶分子的活化并抑制胶质瘤细胞增殖。通过本课题的执行，进一步明确了LRRC4作为胶质瘤抑瘤基因的分子机制：LRRC4可以通过D domain与MEK竞争性结合ERK，将ERK阻滞在胞浆，抑制ERK的活化和核转位，从而影响ERK对下游靶分子的激活，抑制胶质瘤细胞的增殖和侵袭。本研究不仅进一步明确了LRRC4发挥抑瘤作用的分子机制，而且为胶质瘤的发生发展提供了重要的理论基础和实验依据。相关结果发表在国际肿瘤领域重要期刊 (Journal of Hematology & Oncology)上。同时，本研究也为胶质瘤的治疗提供了理想的干预靶点。