Koopman Werner J H, Distelmaier Felix, Hink Mark A, Verkaart Sjoerd, Wijers Mietske, Fransen Jack, Smeitink Jan A M, Willems Peter H G M
Department of Biochemistry, Nijmegen, Nijmegen Centre for Molecular Life Sciences, The Netherlands.
Am J Physiol Cell Physiol. 2008 May;294(5):C1124-32. doi: 10.1152/ajpcell.00079.2008. Epub 2008 Mar 19.
Mitochondria continuously change shape, position, and matrix configuration for optimal metabolite exchange. It is well established that changes in mitochondrial metabolism influence mitochondrial shape and matrix configuration. We demonstrated previously that inhibition of mitochondrial complex I (CI or NADH:ubiquinone oxidoreductase) by rotenone accelerated matrix protein diffusion and decreased the fraction and velocity of moving mitochondria. In the present study, we investigated the relationship between inherited CI deficiency, mitochondrial shape, mobility, and matrix protein diffusion. To this end, we analyzed fibroblasts of two children that represented opposite extremes in a cohort of 16 patients, with respect to their residual CI activity and mitochondrial shape. Fluorescence correlation spectroscopy (FCS) revealed no relationship between residual CI activity, mitochondrial shape, the fraction of moving mitochondria, their velocity, and the rate of matrix-targeted enhanced yellow fluorescent protein (mitoEYFP) diffusion. However, mitochondrial velocity and matrix protein diffusion in moving mitochondria were two to three times higher in patient cells than in control cells. Nocodazole inhibited mitochondrial movement without altering matrix EYFP diffusion, suggesting that both activities are mutually independent. Unexpectedly, electron microscopy analysis revealed no differences in mitochondrial ultrastructure between control and patient cells. It is discussed that the matrix of a moving mitochondrion in the CI-deficient state becomes less dense, allowing faster metabolite diffusion, and that fibroblasts of CI-deficient patients become more glycolytic, allowing a higher mitochondrial velocity.
线粒体不断改变形状、位置和基质结构以实现最佳的代谢物交换。线粒体代谢的变化会影响线粒体形状和基质结构，这一点已得到充分证实。我们之前证明，鱼藤酮抑制线粒体复合物I（CI或NADH：泛醌氧化还原酶）会加速基质蛋白扩散，并降低移动线粒体的比例和速度。在本研究中，我们调查了遗传性CI缺乏、线粒体形状、移动性和基质蛋白扩散之间的关系。为此，我们分析了两名儿童的成纤维细胞，在16名患者队列中，这两名儿童在残余CI活性和线粒体形状方面代表了两个极端。荧光相关光谱法（FCS）显示，残余CI活性、线粒体形状、移动线粒体的比例、其速度以及基质靶向增强型黄色荧光蛋白（mitoEYFP）的扩散速率之间没有关系。然而，患者细胞中移动线粒体的速度和基质蛋白扩散比对照细胞高两到三倍。诺考达唑抑制线粒体移动但不改变基质EYFP扩散，这表明这两种活性相互独立。出乎意料的是，电子显微镜分析显示对照细胞和患者细胞之间的线粒体超微结构没有差异。有人认为，在CI缺乏状态下移动线粒体的基质变得不那么致密，从而允许更快的代谢物扩散，并且CI缺乏患者的成纤维细胞变得更依赖糖酵解，从而允许更高的线粒体速度。
