title: The evolution of Olig genes and their roles in myelination.
abstract: One of the special attributes of vertebrates is their myelinated nervous system. By increasing the conduction velocity of axons, myelin allows for increased body size, rapid movement and a large and complex brain. In the central nervous system (CNS), oligodendrocytes (OLs) are the myelin-forming cells. The transcription factors OLIG1 and OLIG2, master regulators of OL development, presumably also played a seminal role during the evolution of the genetic programme leading to myelination in the CNS. From the available ontogenetic and phylogenetic data we attempt to reconstruct the evolutionary events that led to the emergence of the Olig gene family and speculate about the links between Olig genes, their specific cis-regulatory elements and myelin evolution. In addition, we report a putative myelin basic protein (MBP) ancestor in the lancelet Branchiostoma floridae, which lacks compact myelin. The lancelet 'Mbp' gene lacks the OLIG1/2- and SOX10-binding sites that characterize vertebrate Mbp homologs, raising the possibility that insertion of cis-regulatory elements might have been involved in evolution of the myelinating programme.
authors.affiliation: Wolfson Institute for Biomedical Research and Research, Department of Cell and Developmental Biology, University College London, UK.
authors.forename: Huiliang
authors.initials: H
authors.lastname: Li
authors.forename: William D
authors.initials: WD
authors.lastname: Richardson
mesh_terms: D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics* / Q000378:metabolism*; D019143:Evolution, Molecular; D015870:Gene Expression; D006801:Humans; D009186:Myelin Sheath / Q000235:genetics / Q000502:physiology*; D010802:Phylogeny; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D014714:Vertebrates / Q000235:genetics* / Q000502:physiology
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D020033:Protein Isoforms; D014157:Transcription Factors