Biology Department, University of Genova, Italy.
Cell Biochem Biophys. 2011 Mar;59(2):63-70. doi: 10.1007/s12013-010-9112-1.
F(o)F(1)-ATP synthase is the nanomotor responsible for most of ATP synthesis in the cell. In physiological conditions, it carries out ATP synthesis thanks to a proton gradient generated by the respiratory chain in the inner mitochondrial membrane. We previously reported that isolated myelin vesicles (IMV) contain functional F(o)F(1)-ATP synthase and respiratory chain complexes and are able to conduct an aerobic metabolism, to support the axonal energy demand. In this study, by biochemical assay, Western Blot (WB) analysis and immunofluorescence microscopy, we characterized the IMV F(o)F(1)-ATP synthase. ATP synthase activity decreased in the presence of the specific inhibitors (olygomicin, DCCD, FCCP, valynomicin/nigericin) and respiratory chain inhibitors (antimycin A, KCN), suggesting a coupling of oxygen consumption and ATP synthesis. ATPase activity was inhibited in low pH conditions. WB and microscopy analyses of both IMV and optic nerves showed that the Inhibitor of F(1) (IF(1)), a small protein that binds the F(1) moiety in low pH when of oxygen supply is impaired, is expressed in myelin sheath. Data are discussed in terms of the role of IF(1) in the prevention of the reversal of ATP synthase in myelin sheath during central nervous system ischemic events. Overall, data are consistent with an energetic role of myelin sheath, and may shed light on the relationship among demyelination and axonal degeneration.
F(o)F(1)-ATP 合酶是细胞中大多数 ATP 合成的纳米马达。在生理条件下，它通过线粒体内膜呼吸链产生的质子梯度来进行 ATP 合成。我们之前报道过，分离的髓鞘小泡（IMV）含有功能性 F(o)F(1)-ATP 合酶和呼吸链复合物，能够进行需氧代谢，以支持轴突的能量需求。在这项研究中，通过生化测定、Western Blot（WB）分析和免疫荧光显微镜，我们对 IMV F(o)F(1)-ATP 合酶进行了表征。在存在特异性抑制剂（寡霉素、DCCD、FCCP、缬氨霉素/尼可霉素）和呼吸链抑制剂（抗霉素 A、KCN）的情况下，ATP 合酶活性降低，表明氧消耗和 ATP 合成的偶联。在低 pH 条件下，ATPase 活性受到抑制。WB 和 IMV 及视神经的显微镜分析显示，F(1)的抑制剂（IF(1)）在氧供应受损时在低 pH 下与 F(1)部分结合，在髓鞘中表达。数据是根据 IF(1)在中枢神经系统缺血事件中防止 ATP 合酶在髓鞘中逆转的作用来讨论的。总的来说，数据与髓鞘的能量作用一致，并可能为脱髓鞘和轴突变性之间的关系提供一些启示。
