title: Myelin oligodendrocyte-specific protein is expressed in Müller cells of myelinated vertebrate retinas.
abstract: The retina of nonmammalian vertebrates has a loose myelin that enwraps the large axons of the ganglion cells in all areas, whereas that of mammals lacks myelin, with some exceptions, such as the rabbit retina, which shows compact myelin restricted to the myelinated streak. Electron microscopy studies in chicken retina showed processes of Müller cells (MCs) and oligodendrocytes enwrapping ganglion cell axons. How each of these cells contributes to chicken retina myelination and whether the MC of other myelinated retinas is involved in myelination remain unknown. By immunohistochemistry, with a monoclonal antibody against myelin oligodendrocyte-specific protein (MOSP), we show that MOSP is intensely expressed in the MC and the optic-fiber layer (OFL) in myelinated but not in unmyelinated retinas. By immunocytochemistry with isolated MCs from the chick and rabbit retinas, we show that MOSP is concentrated in the innermost domain of the vitread processes. By immunoblotting, we show that protein extracts from myelinated retinas, but not those from unmyelinated retinas, presented a single band labelled with anti-MOSP of molecular weight similar to that of brain MOSP. In addition, we show that the MC of the embryonic chicken retina starts to express MOSP just before myelination starts. Our results agree with those of electron microscopy studies showing myelin in chick retina formed by MC processes and with those of immunohistochemistry studies in rabbit and human retinas showing expression of other myelin molecules in the MC. Altogether, our results suggest that the MC in myelinated retinas might contribute MOSP to myelin.
authors.affiliation: Departamento de Anatomía e Instituto de Biología del Desarrollo, Facultad de Medicina, Universidad de Sevilla, Sevilla, Spain.
authors.forename: Adela
authors.initials: A
authors.lastname: Quesada
authors.forename: Yolanda
authors.initials: Y
authors.lastname: Aguilera
authors.forename: Rosalía
authors.initials: R
authors.lastname: Caparrós
authors.forename: Francisco A
authors.initials: FA
authors.lastname: Prada
authors.forename: Concepción
authors.initials: C
authors.lastname: Santano
authors.forename: Rosario
authors.initials: R
authors.lastname: López-López
authors.forename: Carmen
authors.initials: C
authors.lastname: Prada
mesh_terms: D000293:Adolescent; D000328:Adult; D000818:Animals; D002642:Chick Embryo; D006801:Humans; D008116:Lizards; D008875:Middle Aged; D009185:Myelin Proteins / Q000096:biosynthesis* / Q000235:genetics; D009186:Myelin Sheath / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D063308:Myelin-Oligodendrocyte Glycoprotein; D009457:Neuroglia / Q000166:cytology* / Q000378:metabolism*; D011817:Rabbits; D051381:Rats; D017208:Rats, Wistar; D012160:Retina / Q000166:cytology* / Q000254:growth & development / Q000378:metabolism*; D012165:Retinal Ganglion Cells / Q000166:cytology / Q000378:metabolism*; D014426:Turtles; D055815:Young Adult
chemical_list: C571326:MOG protein, human; C571328:Mog protein, rat; D009185:Myelin Proteins; D063308:Myelin-Oligodendrocyte Glycoprotein