DIFAR, University of Genova, V.le Benedetto XV, 3 Genova, Italy.
Biochimie. 2013 Nov;95(11):1991-8. doi: 10.1016/j.biochi.2013.07.003. Epub 2013 Jul 12.
The Central Nervous System (CNS) function was shown to be fueled exclusively by oxidative phosphorylation (OXPHOS). This is in line with the sensitivity of brain to hypoxia, but less with the scarcity of the mitochondria in CNS. Consistently with the ectopic expression of FoF1-ATP synthase and the electron transfer chain in myelin, we have reported data demonstrating that isolated myelin vesicles (IMV) conduct OXPHOS. It may suggest that myelin sheath could be a site for the whole aerobic degradation of glucose. In this paper, we assayed the functionality of glycolysis and of TCA cycle enzymes in IMV purified from bovine forebrain. We found the presence and activity of all of the glycolytic and TCA cycle enzymes, comparable to those in mitochondria-enriched fractions, in the same experimental conditions. IMV also contain consistent carbonic anhydrase activity. These data suggest that myelin may be a contributor in energy supply for the axon, performing an extra-mitochondrial aerobic OXPHOS. The vision of myelin as the site of aerobic metabolism may shed a new light on many demyelinating pathologies, that cause an a yet unresolved axonal degeneration and whose clinical onset coincides with myelin development completion.
中枢神经系统（CNS）的功能被证明仅由氧化磷酸化（OXPHOS）提供燃料。这与大脑对缺氧的敏感性一致，但与 CNS 中线粒体的稀缺性不太一致。与髓鞘中 FoF1-ATP 合酶和电子传递链的异位表达一致，我们已经报告了数据，证明分离的髓鞘小泡（IMV）进行 OXPHOS。这可能表明髓鞘鞘可以是葡萄糖进行整个需氧降解的部位。在本文中，我们测定了从牛前脑中纯化的 IMV 中的糖酵解和 TCA 循环酶的功能。在相同的实验条件下，我们发现 IMV 中存在所有糖酵解和 TCA 循环酶，并具有与其在富含线粒体的部分相当的活性。IMV 还含有一致的碳酸酐酶活性。这些数据表明，髓鞘可能是为轴突提供能量供应的贡献者，执行额外的线粒体需氧 OXPHOS。将髓鞘视为有氧代谢部位的观点可能为许多脱髓鞘病理提供新的见解，这些病理导致轴突退化，其临床发作与髓鞘发育完成相吻合。
