hnRNPA1去磷酸化在肿瘤细胞中保护染色体末端的功能机制研究

肿瘤细胞逃避衰老和死亡从而持续增殖的重要原因是其染色体末端的端粒功能异常活跃，但机制远未明了。以往研究证实hnRNPA1通过协助POT1募集至端粒单链DNA避免了染色体粘性末端的裸露，具有防止染色体融合的端粒功能。我们前期发现磷酸化的hnRNPA1与端粒单链DNA有较强的亲和力，然而hnRNPA1不能通过与POT1相结合的方式将其募集至端粒单链DNA，推测极有可能通过hnRNPA1去磷酸化的方式导致其与端粒单链DNA解离，从而为POT1结合端粒单链DNA提供了空间。本项目利用磷酸酶抑制剂和基因敲除肿瘤细胞株等，重点研究hnRNPA1磷酸化和去磷酸化的动态变化机制及其对染色体末端的保护作用，从而为今后开发以hnRNPA1为靶点的抗肿瘤新药提供实验依据和理论基础。

The telomeric activity of chromosome ends is abnormally high in the tumor cells, which is critical for the immortalization of tumor cells, but the mechanism is yet unknow. The previous research has shown that hnRNPA1 is able to assist POT1 in covering the telomeric single-stranded DNA, eventually contributing to prevent the telomere fusion. In our pilot assay, we found that the phosphorylated hnRNPA1 has a high affinity to the telomeric single-stranded DNA, but it is incapable of recruiting POT1 to the telomeric single-stranded DNA via directly interacting with POT1. Therefore, we hypothesized that hnRNPA1could be disassociation of the telomeric single-stranded DNA after dephosphorylation, which provides chance for POT1 binding to the telomeric single-stranded DNA. By means of phosphatase inhibitors and gene knockout cell lines, we focus on elucidating the detailed mechanism of the dynamitic change between phosphorylation and dephosphorylation of hnRNPA1, ultimately corroborating its function of protection of chromosome ends, with hope of providing experimental foundation and theoretical basis to develop the cancer therapy targeting hnRNPA1 in the future.