长链非编码RNA MALAT1在肝细胞癌线粒体中富集调控线粒体的功能及其分子机制

The molecular mechanism of hepatocellular carcinoma (HCC) is complex, which is the key problem to limit the improvement on diagnosis and treatment of HCC. However, the mitochondrial dysfunction is closely related to the occurrence and development of HCC, but the specific regulatory mechanism is remain unclear. We firstly discover that long non-coding RNA MALAT1 is highly enriched in mitochondria of HCC cells and binds to the functional regions of the mitochondrial genome that regulate mitochondrial DNA replication, transcription, and the regions of genes that partially encode the subunits of the oxidative respiratory chain complex. Thus, we propose that MALAT1, transcribed by the intranuclear DNA, transports to mitochondria and regulates mitochondrial oxidative phosphorylation metabolism and other processes to influence the occurrence and development of HCC. This study is based on the application of RNA editing with LwaCas13a targeting the mitochondria. Mitochondrial RNA fluorescence in situ hybridization, RNA reverse transcription associated trap assay and other key technologies will be applied in this study, in order to investigate the clinical significance, the molecular mechanism of transportation of MALAT1 into the mitochondria, the influence of biological function and its molecular mechanism associated with the enrichment of MALAT1 in the mitochondria. It is aimed to reveal the novel mechanism of HCC occurrence and development, so as to make the foundation for the exploration the potential for MALAT1 in mitochondria of HCC as the molecular marker and therapeutic target.

肝细胞癌（HCC）发病分子机制复杂，是限制其诊治水平提高的关键问题，而线粒体功能异常与HCC的发生发展密切相关，但其具体调控机制尚不明确。我们首次发现长链非编码RNA MALAT1在HCC线粒体中高度富集，并与线粒体基因组上调控线粒体DNA复制、转录的功能区域及部分编码氧化呼吸链复合物亚基的基因区域结合。提出细胞核内DNA转录的MALAT1穿梭转运至线粒体，调控线粒体氧化磷酸化代谢等过程，影响HCC发生发展的全新分子机制。本项目在应用靶向线粒体的LwaCas13a RNA编辑技术的基础上，综合应用线粒体RNA荧光原位杂交、RNA逆转录相关捕获法等关键技术，对MALAT1在HCC线粒体中富集的临床意义、穿梭转运的分子机制、恶性生物学功能的影响和在线粒体功能调控中的分子机理等方面进行探究，揭示HCC发生发展的新机制，从而为HCC分子标志物和治疗靶点的发掘奠定基础。

肝细胞癌（HCC）侵袭性强、复发率和死亡率高，探究HCC的发病机制是提高其精准诊治水平的关键环节。本项目通过线粒体转录本高通量测序首次发现，细胞核编码的lncRNA MALAT1在线粒体中富集，线粒体内的MALAT1与线粒体基因组的多个位点相互作用，敲除MALAT1后影响线粒体基因组复制及线粒体基因组结合区域CpG3的甲基化水平，进一步引起线粒体基因转录水平降低。同时本项目揭示了MALAT1穿梭的可能机制：HuR或介导MALAT1由细胞核向线粒体的转运。此外，本研究发现线粒体跨膜蛋白线粒体载体2（MTCH2）与MALAT1相互作用，表明MALAT1可能通过MTCH2进入线粒体内部。细胞核内MALAT1通过在细胞核-线粒体穿梭转运，富集于线粒体，与线粒体基因组相互作用，调控线粒体氧化磷酸化代谢等过程，最终影响HCC发生发展。