title: MBR-1, a novel helix-turn-helix transcription factor, is required for pruning excessive neurites in Caenorhabditis elegans.
abstract: In the developing brain, excessive neurites are actively pruned in the construction and remodeling of neural circuits. We demonstrate for the first time that the pruning of neurites occurs in the simple neural circuit of Caenorhabditis elegans and that a novel transcription factor, MBR-1, is involved in this process. We identified MBR-1 as a C. elegans ortholog of Mblk-1, a transcription factor that is expressed preferentially in the mushroom bodies of the honeybee brain. Although Mblk-1 homologs are conserved among animal species, their roles in the nervous system have never been analyzed. We used C. elegans as an ideal model animal for analysis of neuronal development. mbr-1 is expressed in various neurons in the head and tail ganglia. A comparison of the morphology of mbr-1-expressing neurons revealed that excessive neurites connecting the left and right AIM interneurons are eliminated during larval stages in wild-type but are sustained through the adult stage in the mbr-1 mutant. In addition, mbr-1 expression is regulated by UNC-86, a POU domain transcription factor, and the pruning of the excessive AIM connection is impaired in the unc-86 mutant. These findings provide an important clue for further genetic dissection of neurite pruning.
authors.affiliation: Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo 113-0033, Japan.
authors.forename: Eriko
authors.initials: E
authors.lastname: Kage
authors.forename: Yu
authors.initials: Y
authors.lastname: Hayashi
authors.forename: Hideaki
authors.initials: H
authors.lastname: Takeuchi
authors.forename: Takaaki
authors.initials: T
authors.lastname: Hirotsu
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Kunitomo
authors.forename: Takao
authors.initials: T
authors.lastname: Inoue
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Arai
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Iino
authors.forename: Takeo
authors.initials: T
authors.lastname: Kubo
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D017173:Caenorhabditis elegans / Q000378:metabolism*; D029742:Caenorhabditis elegans Proteins / Q000235:genetics; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D040461:Gene Components; D018507:Gene Expression Regulation, Developmental; D049452:Green Fluorescent Proteins; D019077:Helix-Turn-Helix Motifs / Q000235:genetics*; D018398:Homeodomain Proteins / Q000235:genetics; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D016501:Neurites / Q000378:metabolism*; D009474:Neurons / Q000166:cytology* / Q000378:metabolism; D050809:POU Domain Factors / Q000235:genetics; D017422:Sequence Analysis, DNA; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: D029742:Caenorhabditis elegans Proteins; D018398:Homeodomain Proteins; C508848:MBR-1 protein, C elegans; D050809:POU Domain Factors; D014157:Transcription Factors; C081539:unc-86 protein, C elegans; D049452:Green Fluorescent Proteins