Meo-Evoli Nathalie, Almacellas Eugènia, Massucci Francesco Alessandro, Gentilella Antonio, Ambrosio Santiago, Kozma Sara C, Thomas George, Tauler Albert
Departament de Bioquímica i Biologia Molecular, Facultat de Farmàcia, Universitat de Barcelona, 08028 Barcelona, Catalunya, Spain.
Laboratory of Cancer Metabolism, IDIBELL, Hospital Duran i Reynals, 08908 L'Hospitalet de Llobregat, Barcelona, Catalunya, Spain.
Oncotarget. 2015 Sep 29;6(29):28057-70. doi: 10.18632/oncotarget.4812.
In addition to being a master regulator of cell cycle progression, E2F1 regulates other associated biological processes, including growth and malignancy. Here, we uncover a regulatory network linking E2F1 to lysosomal trafficking and mTORC1 signaling that involves v-ATPase regulation. By immunofluorescence and time-lapse microscopy we found that E2F1 induces the movement of lysosomes to the cell periphery, and that this process is essential for E2F1-induced mTORC1 activation and repression of autophagy. Gain- and loss-of-function experiments reveal that E2F1 regulates v-ATPase activity and inhibition of v-ATPase activity repressed E2F1-induced lysosomal trafficking and mTORC1 activation. Immunoprecipitation experiments demonstrate that E2F1 induces the recruitment of v-ATPase to lysosomal RagB GTPase, suggesting that E2F1 regulates v-ATPase activity by enhancing the association of V0 and V1 v-ATPase complex. Analysis of v-ATPase subunit expression identified B subunit of V0 complex, ATP6V0B, as a transcriptional target of E2F1. Importantly, ATP6V0B ectopic-expression increased v-ATPase and mTORC1 activity, consistent with ATP6V0B being responsible for mediating the effects of E2F1 on both responses. Our findings on lysosomal trafficking, mTORC1 activation and autophagy suppression suggest that pharmacological intervention at the level of v-ATPase may be an efficacious avenue for the treatment of metastatic processes in tumors overexpressing E2F1.
除了作为细胞周期进程的主要调节因子外,E2F1还调节其他相关的生物学过程,包括生长和恶性肿瘤。在这里,我们揭示了一个将E2F1与溶酶体运输和mTORC1信号传导联系起来的调节网络,该网络涉及v-ATP酶调节。通过免疫荧光和延时显微镜观察,我们发现E2F1诱导溶酶体向细胞周边移动,并且这个过程对于E2F1诱导的mTORC1激活和自噬抑制至关重要。功能获得和功能丧失实验表明,E2F1调节v-ATP酶活性,而抑制v-ATP酶活性可抑制E2F1诱导的溶酶体运输和mTORC1激活。免疫沉淀实验表明,E2F1诱导v-ATP酶募集到溶酶体RagB GTP酶,这表明E2F1通过增强V0和V1 v-ATP酶复合物的结合来调节v-ATP酶活性。对v-ATP酶亚基表达的分析确定V0复合物的B亚基ATP6V0B是E2F1的转录靶点。重要的是,ATP6V0B的异位表达增加了v-ATP酶和mTORC活性,这与ATP6V0B负责介导E2F1对这两种反应的作用一致。我们关于溶酶体运输、mTORC1激活和自噬抑制的研究结果表明,在v-ATP酶水平进行药物干预可能是治疗过表达E2F1的肿瘤转移过程的有效途径。