title: Ceramide galactosyltransferase expression is regulated positively by Nkx2.2 and negatively by OLIG2.
abstract: Myelin, a multilamellar structure extended from oligodendrocytes or Schwann cells, plays a critical role in maintenance of neuronal function, and damage or loss of myelin causes demyelinating diseases such as multiple sclerosis. For precise alignment of the myelin sheath, there is a requirement for expression of galactosylceramide (GalCer), a major glycosphingolipid in myelin. Synthesis of GalCer is strictly limited in oligodendrocytes in a developmental stage-specific manner. Ceramide galactosyltransferase (CGT), a key enzyme for biosynthesis of GalCer, exhibits restricted expression in oligodendrocytes but the mechanism is poorly understood. Based on our assumption that particular oligodendrocyte-lineage-specific transcription factors regulate CGT expression, we co-expressed a series of candidate transcription factors with the human CGT promoter-driving luciferase expression in oligodendroglioma cells to measure the promoter activity. We found that Nkx2.2 strongly activated the CGT promoter. In addition, we identified a novel repressive DNA element in the first intron of CGT and OLIG2, an oligodendrocyte-specific transcription factor, as a binding protein of this element. Moreover, overexpression of OLIG2 completely canceled the activating effect of Nkx2.2 on CGT promoter activity. Expression of CGT mRNA was also upregulated by Nkx2.2, but this upregulation was cancelled by co-expression of OLIG2 with Nkx2.2. Our study suggests that CGT expression is controlled by balanced expression of the negative modulator OLIG2 and positive regulator Nkx2.2, providing new insights into how expression of GalCer is tightly regulated in cell-type- and stage-specific manners.
authors.affiliation: Disease Glycomics Team, Systems Glycobiology Research Group, RIKEN-Max Planck Joint Research Center, Global Research Cluster, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
authors.forename: Kyohei
authors.initials: K
authors.lastname: Okahara
authors.affiliation: Disease Glycomics Team, Systems Glycobiology Research Group, RIKEN-Max Planck Joint Research Center, Global Research Cluster, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
authors.forename: Yasuhiko
authors.initials: Y
authors.lastname: Kizuka
authors.affiliation: Disease Glycomics Team, Systems Glycobiology Research Group, RIKEN-Max Planck Joint Research Center, Global Research Cluster, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
authors.forename: Shinobu
authors.initials: S
authors.lastname: Kitazume
authors.affiliation: Disease Glycomics Team, Systems Glycobiology Research Group, RIKEN-Max Planck Joint Research Center, Global Research Cluster, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
authors.forename: Fumi
authors.initials: F
authors.lastname: Ota
authors.affiliation: Molecular Membrane Neuroscience.
authors.forename: Kazuki
authors.initials: K
authors.lastname: Nakajima
authors.affiliation: Molecular Membrane Neuroscience.
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Hirabayashi
authors.affiliation: Laboratory for Molecular Psychiatry, RIKEN Brain Science Institute, RIKEN, Hirosawa 2-1, Wako, Saitama 351-0198, Japan.
authors.forename: Motoko
authors.initials: M
authors.lastname: Maekawa
authors.affiliation: Laboratory for Molecular Psychiatry, RIKEN Brain Science Institute, RIKEN, Hirosawa 2-1, Wako, Saitama 351-0198, Japan.
authors.forename: Takeo
authors.initials: T
authors.lastname: Yoshikawa
authors.affiliation: Disease Glycomics Team, Systems Glycobiology Research Group, RIKEN-Max Planck Joint Research Center, Global Research Cluster, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan tani52@wd5.so-net.ne.jp.
authors.forename: Naoyuki
authors.initials: N
authors.lastname: Taniguchi
mesh_terms: D051792:Basic Helix-Loop-Helix Proteins / Q000096:biosynthesis* / Q000235:genetics; D002454:Cell Differentiation / Q000235:genetics; D005699:Galactosylceramides / Q000096:biosynthesis / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic / Q000235:genetics; D006367:HeLa Cells; D000090322:Homeobox Protein Nkx-2.2; D018398:Homeodomain Proteins / Q000096:biosynthesis* / Q000378:metabolism; D006801:Humans; D009103:Multiple Sclerosis / Q000235:genetics* / Q000473:pathology; D009186:Myelin Sheath / Q000378:metabolism / Q000473:pathology; D051146:N-Acylsphingosine Galactosyltransferase / Q000096:biosynthesis / Q000235:genetics*; D009419:Nerve Tissue Proteins / Q000096:biosynthesis* / Q000235:genetics; D009687:Nuclear Proteins; D000076104:Oligodendrocyte Transcription Factor 2; D009836:Oligodendroglia / Q000201:enzymology / Q000378:metabolism; D011401:Promoter Regions, Genetic; D014157:Transcription Factors / Q000096:biosynthesis* / Q000378:metabolism; D029961:Zebrafish Proteins
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D005699:Galactosylceramides; D000090322:Homeobox Protein Nkx-2.2; D018398:Homeodomain Proteins; D051146:N-Acylsphingosine Galactosyltransferase; D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins; D000076104:Oligodendrocyte Transcription Factor 2; D014157:Transcription Factors; D029961:Zebrafish Proteins; C000715631:NKX2-2 protein, human; C405708:OLIG2 protein, human; C000715630:nkx2.2b protein, zebrafish
keywords: Nkx2.2; OLIG2; ceramide galactosyltransferase; galactosylceramide; oligodendrocyte