Regenerative Medicine Research Center, West China Hospital, Sichuan University, Sichuan, 610041, China.
Memphis Institute of Regenerative Medicine, University of Tennessee Health Science Center, Memphis, TN 38163, USA.
Exp Biol Med (Maywood). 2021 Jan;246(1):97-105. doi: 10.1177/1535370220964394. Epub 2020 Nov 10.
Previous studies demonstrated that mitochondrial fission arguments the stemness of bone marrow-derived mesenchymal stem cells (BMSCs). Because mitophagy is critical in removing damaged or surplus mitochondrial fragments and maintaining mitochondrial integrity, the present study was undertaken to test the hypothesis that mitophagy is involved in mitochondrial fission-enhanced stemness of BMSCs. Primary cultures of rat BMSCs were treated with tyrphostin A9 (TA9, a potent inducer of mitochondrial fission) to increase mitochondrial fission, which was accompanied by enhanced mitophagy as defined by increased co-staining of MitoTracker Green for mitochondria and LysoTracker Deep Red for lysosomes, as well as the increased co-localization of autophagy markers (LC3B, P62) and mitochondrial marker (Tom20). A mitochondrial uncoupler, carbonyl cyanide 4-(trifluoromethoxy) phenylhydrazone (FCCP) was used to promote mitophagy, which was confirmed by an increased co-localization of mitochondrial and lysosome biomarkers. The argumentation of mitophagy was associated with enhanced stemness of BMSCs as defined by increased expression of stemness markers Oct4 and Sox2, and enhanced induction of BMSCs to adipocytes or osteocytes. Conversely, transfection of BMSCs with siRNA targeting mitophagy-essential genes / led to diminished stemness of the stem cells, as defined by depressed stemness markers. Importantly, concomitant promotion of mitochondrial fission and inhibition of mitophagy suppressed the stemness of BMSCs. These results thus demonstrate that mitophagy is critically involved in mitochondrial fission promotion of the stemness of BMSCs.
先前的研究表明，线粒体裂变促进骨髓间充质干细胞（BMSCs）的干性。由于自噬在清除受损或多余的线粒体片段和维持线粒体完整性方面至关重要，本研究旨在检验自噬是否参与线粒体裂变增强 BMSCs 干性的假说。用 tyrphostin A9（TA9，一种有效的线粒体裂变诱导剂）处理大鼠 BMSCs 原代培养物以增加线粒体裂变，这伴随着自噬的增强，这可以通过线粒体的 MitoTracker Green 和溶酶体的 LysoTracker Deep Red 的共染色增加来定义，以及自噬标记物（LC3B、P62）和线粒体标记物（Tom20）的共定位增加来定义。使用线粒体解偶联剂羰基氰化物 4-（三氟甲氧基）苯腙（FCCP）促进自噬，这可以通过线粒体和溶酶体生物标志物的共定位增加来证实。自噬的增强与 BMSCs 干性的增强有关，这可以通过干性标志物 Oct4 和 Sox2 的表达增加以及 BMSCs 向脂肪细胞或成骨细胞的诱导增强来定义。相反，用针对自噬必需基因的 siRNA 转染 BMSCs 会导致干细胞干性降低，这可以通过降低干性标志物来定义。重要的是，同时促进线粒体裂变和抑制自噬会抑制 BMSCs 的干性。因此，这些结果表明自噬在促进线粒体裂变增强 BMSCs 干性中起着至关重要的作用。
