Functional Expression of Electron Transport Chain and FoF1-ATP Synthase in Optic Nerve Myelin Sheath

Neurochem Res. 2015 Nov;40(11):2230-41. doi: 10.1007/s11064-015-1712-0. Epub 2015 Sep 3.


Our previous studies reported evidence for aerobic ATP synthesis by myelin from both bovine brainstem and rat sciatic nerve. Considering that the optic nerve displays a high oxygen demand, here we evaluated the expression and activity of the five Respiratory Complexes in myelin purified from either bovine or murine optic nerves. Western blot analyses on isolated myelin confirmed the expression of ND4L (subunit of Complex I), COX IV (subunit of Complex IV) and β subunit of F1Fo-ATP synthase. Moreover, spectrophotometric and in-gel activity assays on isolated myelin, as well as histochemical activity assays on both bovine and murine transversal optic nerve sections showed that the respiratory Complexes are functional in myelin and are organized in a supercomplex. Expression of oxidative phosphorylation proteins was also evaluated on bovine optic nerve sections by confocal and transmission electron microscopy. Having excluded a mitochondrial contamination of isolated myelin and considering the results form in situ analyses, it is proposed that the oxidative phosphorylation machinery is truly resident in optic myelin sheath. Data may shed a new light on the unknown trophic role of myelin sheath. It may be energy supplier for the axon, explaining why in demyelinating diseases and neuropathies, myelin sheath loss is associated with axonal degeneration.

Keywords: ATP synthesis; Glia metabolism; Myelin sheath; Optic nerve; Oxidative phosphorylation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine Triphosphate / biosynthesis
  • Animals
  • Axons / metabolism
  • Cattle
  • Electron Transport Chain Complex Proteins / biosynthesis*
  • Male
  • Mice
  • Mitochondria / metabolism
  • Myelin Sheath / metabolism*
  • NADH Dehydrogenase / biosynthesis
  • Neuroglia / metabolism
  • Optic Nerve / metabolism*
  • Oxidative Phosphorylation
  • Proton-Translocating ATPases / biosynthesis*


  • Electron Transport Chain Complex Proteins
  • NADH dehydrogenase subunit 4
  • Adenosine Triphosphate
  • NADH Dehydrogenase
  • Proton-Translocating ATPases