Beclin 1的泛素化调控在胃癌细胞自噬及肿瘤进展中的机制研究

Our initial research indicates Beclin 1 low expression is closely associate with the gastric cancer patient prognosis, but the mechanism is not clear. Our hypothesis is that ubiquitination of Beclin 1 may lead to its low expression, which bring out the development of stomach cancer. Through the ubiquitin ligase E3 screening and preliminary verification, we found the Skp2 ubiquitination regulation can cause the degradation of Beclin 1. We will investigate the interaction between Skp2 and Beclin 1.Using knockdown/overexpress Skp2/Beclin1 and contructing mutanted Skp2,we can detect related autophagic molecular expression and show the regulation of autophagy by Skp2 is relying on the Beclin 1 ubiquitination.This study will clarify the molecular mechanism that ubiquitination of Beclin 1 in regulating gastric cancer cell autophagy and tumor progression, and may provide new information for diagnosis and targeted therapies in gastric cancer.

我们前期研究证明Beclin 1低表达与胃癌的进展密切相关，但其机制尚不明确。我们推测：泛素化作为真核生物体内蛋白质最关键的降解途径，可能引起其低表达，进而导致胃癌进展。我们通过多个泛素连接酶的筛选及体外验证，发现原癌基因Skp2泛素化调节可以引起Beclin 1的降解。本课题将通过蛋白结合实验寻找其结合区域，利用下调及过表达Skp2测定Beclin 1稳定性影响，观测电镜下自噬泡变化，构建Skp2突变体及同时下调Skp2及Beclin 1验证胃癌细胞中自噬的调节依赖Beclin1的泛素化。本研究通过阐明泛素化调控胃癌细胞自噬及肿瘤进展的分子机制，将为胃癌的诊治提供新的思路。

我们前期已经发表文章证明Beclin 1 的低表达与胃癌进展密切相关。本年度的主要工作是进一步验证了是Skp2对beclin 1的泛素化调控，同时我们偶然发现mTOR、Ampk等能够磷酸化Skp2，并能够在体内结合，导致Skp2对Beclin 1泛素化减少及skp2复合体的形成减少。其磷酸化位点及相关机制仍在探索中。