A threshold of transmembrane potential is required for mitochondrial dynamic balance mediated by DRP1 and OMA1.
A threshold of transmembrane potential is required for mitochondrial dynamic balance mediated by DRP1 and OMA1.
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DOI：
10.1007/s00018-016-2421-9
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发表时间：
2017-04
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影响因子：
--
通讯作者：
Gilkerson R
中科院分区：
文献类型：
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作者：
Jones E;Gaytan N;Garcia I;Herrera A;Ramos M;Agarwala D;Rana M;Innis-Whitehouse W;Schuenzel E;Gilkerson R
作为细胞器网络，线粒体通过相反的融合和分裂途径动态调节其组织，以维持生物能量稳态并有助于关键的细胞途径。这种动态平衡与生物能量功能直接相关：跨内膜跨膜电位（Δ μ m）的丧失破坏了线粒体分裂/融合平衡，导致网络碎片化。然而，线粒体动态平衡所需的Δ λ m水平，以及裂变和融合途径的相对贡献仍然不清楚。为了探索这一点，线粒体形态和Δ m分别通过共聚焦成像和四甲基罗丹明酯（TMRE）流式细胞术，在培养的143 B骨肉瘤细胞进行了检查。当将未处理的143 B细胞的TMRE值标准化为100%时，低于34% TMRE荧光的遗传（mtDNA耗尽的ρ0）和药理学[羰基氰间氯苯腙（CCCP）处理的]细胞模型都无法维持线粒体互连，这与融合活性长OPA 1亚型（L-OPA 1）的丧失相关。从机制上讲，这个阈值是通过DRP 1介导的分裂和OPA 1介导的融合的机制协调来维持的：缺乏DRP 1或OMA 1金属蛋白酶的细胞对Δ λ m的丧失不敏感，而是维持专性融合的形态。总的来说，这些研究结果表明，线粒体的“临界点”阈值介导的相互作用的Δ m与DRP 1和OMA 1;此外，DRP 1似乎需要有效的OPA 1的维护和加工，与裂变和融合途径的直接相互作用的证据越来越多的一致。这些结果表明，低于阈值的Δ λ m协调激活OPA 1的DRP 1介导的裂变和OMA 1切割，破坏线粒体动态平衡，对一系列信号传导途径和细胞生命/死亡事件具有重要意义。本文的在线版本（doi：10.1007/s 00018 -016-2421-9）包含补充材料，可供授权用户使用。
As an organellar network, mitochondria dynamically regulate their organization via opposing fusion and fission pathways to maintain bioenergetic homeostasis and contribute to key cellular pathways. This dynamic balance is directly linked to bioenergetic function: loss of transmembrane potential across the inner membrane (Δψ m) disrupts mitochondrial fission/fusion balance, causing fragmentation of the network. However, the level of Δψ m required for mitochondrial dynamic balance, as well as the relative contributions of fission and fusion pathways, have remained unclear. To explore this, mitochondrial morphology and Δψ m were examined via confocal imaging and tetramethyl rhodamine ester (TMRE) flow cytometry, respectively, in cultured 143B osteosarcoma cells. When normalized to the TMRE value of untreated 143B cells as 100%, both genetic (mtDNA-depleted ρ0) and pharmacological [carbonyl cyanide m-chlorophenyl hydrazone (CCCP)-treated] cell models below 34% TMRE fluorescence were unable to maintain mitochondrial interconnection, correlating with loss of fusion-active long OPA1 isoforms (L-OPA1). Mechanistically, this threshold is maintained by mechanistic coordination of DRP1-mediated fission and OPA1-mediated fusion: cells lacking either DRP1 or the OMA1 metalloprotease were insensitive to loss of Δψ m, instead maintaining an obligately fused morphology. Collectively, these findings demonstrate a mitochondrial ‘tipping point’ threshold mediated by the interaction of Δψ m with both DRP1 and OMA1; moreover, DRP1 appears to be required for effective OPA1 maintenance and processing, consistent with growing evidence for direct interaction of fission and fusion pathways. These results suggest that Δψ m below threshold coordinately activates both DRP1-mediated fission and OMA1 cleavage of OPA1, collapsing mitochondrial dynamic balance, with major implications for a range of signaling pathways and cellular life/death events. The online version of this article (doi:10.1007/s00018-016-2421-9) contains supplementary material, which is available to authorized users.