The proteome of human retrobulbar optic nerve

The optic nerve is a white matter tract that conveys visual information to the brain. A detailed investigation of the proteome of the normal human retrobulbar optic nerve may help facilitate studies of the biology and pathophysiology of the optic nerve. We conducted an in-depth proteomic analysis of optic nerve from five adults. Proteins were fractionated using SDS-PAGE. After in-gel digestion, peptides were analyzed using LC-MS/MS on an Orbitrap Elite mass spectrometer. We identified 2,711 non-redundant proteins in the human retrobulbar optic nerve, including the astrocytic marker glial fibrillary acidic protein, several proteins expressed by oligodendrocytes (laminin, proteolipid protein, and fibronectin), myelin proteins (myelin basic protein, myelin-associated glycoprotein), paranodal structural proteins (neurofascin, contactin, α, β, and γ adducins, septin 2, endophilin, ankyrin β, spectrin), proteins involved in neuronal protection and regeneration (α crytallins A and B, dedicator of cytokinesis proteins, ciliary neurotrophic factor), proteins associated with open-angle glaucoma (thioredoxin, heat shock protein-70), and proteins associated with optic neuritis (aquaporin-4). Twenty-one unambiguous protein isoforms were identified in the optic nerve.