Schimmel Brixey G, Berbusse Gregory W, Naylor Kari
Biology Department, University of Central Arkansas, Conway, AR 72035, USA.
BMC Res Notes. 2012 Sep 14;5:505. doi: 10.1186/1756-0500-5-505.
Mitochondrial morphology is maintained by two distinct membrane events -fission and fusion. Altering these conserved processes can disrupt mitochondrial morphology and distribution, thereby disrupting the organelle's functionality and impeding cellular function. In higher eukaryotes, these processes are mediated by a family of dynamin-related proteins (DRP's). In the lower eukaryotes, for instance Dictyostelium discoideum, mitochondrial fission and fusion have been implicated but not yet established. To understand the overall mechanism of these dynamics across organisms, we developed an assay to identify fission and fusion events in Dictyostelium and to assess the involvement of the mitochondrial proteins, MidA, CluA, and two DRP's, DymA and DymB.
Using laser scanning confocal microscopy we show, for the first time, that lower eukaryotes mediate mitochondrial fission and fusion. In Dictyostelium, these processes are balanced, occurring approximately 1 event/minute. Quantification of the rates in midA-, cluA-, dymA-, or dymB- strains established that MidA appears to play an indirect role in the regulation of fission and fusion, while the DRP's are not essential for these processes. Rates of fission and fusion were significantly reduced in cluA-cells, indicating that CluA is necessary for maintaining both fission and fusion.
We have successfully demonstrated that Dictyostelium mitochondria undergo the dynamic processes of fission and fusion. The classical mediators of membrane dynamics - the DRP's - are not necessary for these dynamics, whereas CluA is necessary for both processes. This work contributes to our overall understanding of mitochondrial dynamics and ultimately will provide additional insight into mitochondrial disease.
线粒体形态由两种不同的膜事件维持——裂变和融合。改变这些保守过程会破坏线粒体形态和分布，从而扰乱细胞器的功能并阻碍细胞功能。在高等真核生物中，这些过程由动力蛋白相关蛋白家族（DRP）介导。在低等真核生物中，例如盘基网柄菌，线粒体裂变和融合已被提及，但尚未得到证实。为了了解这些跨生物体动态的整体机制，我们开发了一种检测方法来识别盘基网柄菌中的裂变和融合事件，并评估线粒体蛋白MidA、CluA以及两种DRP蛋白DymA和DymB的参与情况。
我们首次使用激光扫描共聚焦显微镜表明，低等真核生物介导线粒体裂变和融合。在盘基网柄菌中，这些过程是平衡的，大约每分钟发生1次事件。对midA -、cluA -、dymA -或dymB -菌株中速率的量化确定，MidA似乎在裂变和融合的调节中起间接作用，而DRP对这些过程并非必不可少。cluA细胞中的裂变和融合速率显著降低，表明CluA对于维持裂变和融合都是必需的。
我们成功证明了盘基网柄菌线粒体经历裂变和融合的动态过程。膜动态的经典介导因子——DRP——对这些动态并非必需，但CluA对这两个过程都是必需的。这项工作有助于我们对线粒体动态的整体理解，并最终将为线粒体疾病提供更多见解。
