Mieap-induced accumulation of lysosomes within mitochondria (MALM) regulates gastric cancer cell invasion under hypoxia by suppressing reactive oxygen species accumulation
Mieap-induced accumulation of lysosomes within mitochondria (MALM) regulates gastric cancer cell invasion under hypoxia by suppressing reactive oxygen species accumulation
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DOI：
10.1038/s41598-019-39563-x
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发表时间：
2019-02-26
影响因子：
4.6
通讯作者：
Noshiro, Hirokazu
中科院分区：
文献类型：
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作者：
Okuyama, Keiichiro;Kitajima, Yoshihiko;Noshiro, Hirokazu
线粒体质量控制（MQC）可以防止潜在的破坏性事件，如线粒体活性氧（mtROS）的过度产生。我们研究了两个主要的MQC过程，即线粒体自噬和Mieap诱导的线粒体内溶酶体积累（MALM），对两个人胃癌（GC）细胞系缺氧反应的贡献。我们发现，缺氧增加了线粒体ROS的产生和细胞侵袭58As9，但不是在MKN 45，虽然转录因子缺氧诱导因子1 α诱导在两个细胞系。溶酶体与线粒体的共定位仅在缺氧的MKN 45细胞中发现，这表明缺氧诱导的MQC在MKN 45中功能正常，但在58 As 9中可能受损。缺氧并没有导致线粒体质量或DNA减少或改变外观的自噬体，通过电子显微镜判断，这表明线粒体自噬在两种细胞系中均未诱导。然而，蛋白质印迹分析揭示了MALM相关蛋白Mieap、BNIP3和BNIP3L以及溶酶体蛋白组织蛋白酶D在缺氧条件下的MKN 45细胞的线粒体部分中的存在。最后，在MKN 45细胞中，Mieap敲低导致低氧下mtROS积累和细胞侵袭增加。我们的研究结果表明，缺氧诱导的MALM抑制GC细胞的侵袭，防止线粒体ROS的产生。
Mitochondrial quality control (MQC) protects against potentially damaging events, such as excessive generation of mitochondrial reactive oxygen species (mtROS). We investigated the contribution of the two major MQC processes, namely, mitophagy and Mieap-induced accumulation of lysosomes within mitochondria (MALM), to the response to hypoxia of two human gastric cancer (GC) cell lines. We found that hypoxia increased mtROS generation and cell invasion in 58As9, but not in MKN45, although the transcription factor hypoxia-inducible factor 1 alpha was induced in both cell lines. Colocalisation of lysosomes with mitochondria was found only in hypoxic MKN45 cells, suggesting that hypoxia-induced MQC functions normally in MKN45 but may be impaired in 58As9. Hypoxia did not lead to decreased mitochondrial mass or DNA or altered appearance of autophagosomes, as judged by electron microscopy, suggesting that mitophagy was not induced in either cell line. However, western blot analysis revealed the presence of the MALM-associated proteins Mieap, BNIP3 and BNIP3L, and the lysosomal protein cathepsin D in the mitochondrial fraction of MKN45 cells under hypoxia. Finally, Mieap knockdown in MKN45 cells resulted in increased mtROS accumulation and cell invasion under hypoxia. Our results suggest that hypoxia-induced MALM suppresses GC cell invasion by preventing mtROS generation.