RNF115调控自噬体成熟的分子机制以及在肿瘤发生发展中的作用

RNF115, an autophagy-related molecule, was first identified in our laboratory by high-throughput functional genome screening. The gene is evolutionarily conserved and widely expressed. Our previous studies have shown that the silencing of RNF115 can increase the accumulation of autophagosome in basal and stress conditions, inhibit the removal of autophagic substrates. Further studies have shown that RNF115 can interact not only with activated form of Rab7, but also with LC3,ATG14,HOPS subunit VPS39 and VPS40. Inactivation of RNF115 can increase the instability of STX17 protein and decrease the co-localization between autophagosome and lysosome. It is suggested for the first time that RNF115 may positively regulate the fusion of autophagosome-late endosome / lysosome. On the basis of previous studies, this subject intends to further elaborate the molecular mechanism of RNF115-regulating autophagy in normal and stressed states by using various molecular cell biology techniques, combined with TNF115 gene knockout mice and tumor animal models. We will further demonstrate the role of RNF115-target signaling in maintaining autophagy homeostasis and its pathophysiological significance. These achieved results are expected to provide new content or clues for the regulatory network of autophagosome maturation, which have important theoretical significance and potential application value.

RNF115是本室在高通量功能基因组筛选中鉴定的自噬相关分子。前期研究证明，RNF115沉默能够增加本底以及应激细胞中自噬体的累积，自噬底物清除障碍。进一步的研究证明，RNF115既能与活化形式的Rab7结合，也能与LC3、STX17、ATG14、HOPS亚基VPS39以及VPS40发生相互作用，RNF115灭活能够增加STX17蛋白的不稳定性，减少自噬体与溶酶体的共定位，首次证明RNF115能够正向调控自噬体-晚期内体/溶酶体融合。本课题将在前期研究的基础上，进一步利用分子细胞生物学等研究手段，结合RNF115基因敲除小鼠以及动物模型等，系统阐述RNF115在正常和应激状态下调控自噬体成熟的分子机制，证明RNF115-靶分子信号在维持自噬稳态中的作用以及病理生理意义，这些研究成果的取得，有望为复杂的自噬体成熟调控网络提供新的内容或线索，具有重要的理论意义以及潜在的应用价值。

E3连接酶RNF115（Ring finger protein 115）又称为 乳腺癌相关基因2（Breast cancer-associated gene 2，BCA2），是一个与乳腺癌发生发展密切相关的基因。我们的研究首次发现，RNF115/BCA2在胃癌和肝癌组织中表达明显高于相对应的非肿瘤组织，并与肿瘤患者的生存率呈现明显的负相关,低表达RNF115的癌症患者生存期显著延长。体内外的实验包括裸鼠移植瘤的研究证明，沉默RNF115/BCA2能够减弱胃癌和肝癌细胞的活力、增殖，以及肝癌细胞的迁移，抑制小鼠体内的成瘤能力。进一步的研究证明，RNF115/BCA2能够在不同的肿瘤细胞中调控细胞自噬，分子机制的研究证明，RNF115能够与STX17、RAB7、HOPS复合物、ATG14以及LC3家族分子结合，因此，RNF115能够从多个层面调控细胞自噬体的形成、自噬体与溶酶体的融合、以及自噬溶酶体对自噬底物的降解，该研究对于揭示自噬的分子调控网络提供了新的线索和内容。Rnf115基因敲除小鼠的研究数据证明，Rnf115-/-小鼠能够上调肝细胞自噬，显著抑制DEN诱导的小鼠肝癌发生发展,。我们的研究还首次发现，Rnf115-/-小鼠能够通过上调细胞自噬清除受损的线粒体，抑制LPS/D-GalN引起的急性肝脏损伤，减弱肝脏的出血坏死；同时Rnf115-/-巨噬细胞的活化受损，降低了LPS诱导的炎症反应，该研究为进一步从不同层面理解RNF115的病理生理学功能提供了证据，具有潜在的应用价值。