title: An evolutionarily conserved protein CHORD regulates scaling of dendritic arbors with body size.
abstract: Most organs scale proportionally with body size through regulation of individual cell size and/or cell number. Here we addressed how postmitotic and morphologically complex cells such as neurons scale with the body size by using the dendritic arbor of one Drosophila sensory neuron as an assay system. In small adults eclosed under a limited-nutrition condition, the wild-type neuron preserved the branching complexity of the arbor, but scaled down the entire arbor, making a "miniature". In contrast, mutant neurons for the Insulin/IGF signaling (IIS) or TORC1 pathway exhibited "undergrowth", which was characterized by decreases in both the branching complexity and the arbor size, despite a normal diet. These contrasting phenotypes hinted that a novel regulatory mechanism contributes to the dendritic scaling in wild-type neurons. Indeed, we isolated a mutation in the gene CHORD/morgana that uncoupled the neuron size and the body size: CHORD mutant neurons generated miniature dendritic arbors regardless of the body size. CHORD encodes an evolutionarily conserved co-chaperone of HSP90. Our results support the notion that dendritic growth and branching are controlled by partly separate mechanisms. The IIS/TORC1 pathways control both growth and branching to avert underdevelopment, whereas CHORD together with TORC2 realizes proportional scaling of the entire arbor.
authors.affiliation: Graduate School of Biostudies, Kyoto University, Kyoto 606-8501, Japan.
authors.forename: Kohei
authors.initials: K
authors.lastname: Shimono
authors.affiliation: Institute for Integrated Cell-Material Sciences (WPI-iCeMS), Kyoto University Kyoto 606-8501, Japan.
authors.forename: Kazuto
authors.initials: K
authors.lastname: Fujishima
authors.affiliation: Graduate School of Biostudies, Kyoto University, Kyoto 606-8501, Japan.
authors.forename: Takafumi
authors.initials: T
authors.lastname: Nomura
authors.affiliation: Graduate School of Biostudies, Kyoto University, Kyoto 606-8501, Japan.
authors.forename: Masayoshi
authors.initials: M
authors.lastname: Ohashi
authors.affiliation: Graduate School of Biostudies, Kyoto University, Kyoto 606-8501, Japan.
authors.forename: Tadao
authors.initials: T
authors.lastname: Usui
authors.affiliation: 1] Graduate School of Biostudies, Kyoto University, Kyoto 606-8501, Japan [2] Institute for Integrated Cell-Material Sciences (WPI-iCeMS), Kyoto University Kyoto 606-8501, Japan.
authors.forename: Mineko
authors.initials: M
authors.lastname: Kengaku
authors.affiliation: Center for Information Biology, National Institute of Genetics, Mishima, Shizuoka, Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Toyoda
authors.affiliation: Graduate School of Biostudies, Kyoto University, Kyoto 606-8501, Japan.
authors.forename: Tadashi
authors.initials: T
authors.lastname: Uemura
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D049628:Body Size; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D048429:Cell Size; D017124:Conserved Sequence; D003712:Dendrites / Q000378:metabolism* / Q000648:ultrastructure; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000033:anatomy & histology / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D019143:Evolution, Molecular; D005260:Female; D018507:Gene Expression Regulation, Developmental; D007328:Insulin / Q000235:genetics / Q000378:metabolism; D000076225:Mechanistic Target of Rapamycin Complex 2; D018832:Molecular Chaperones / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D046912:Multiprotein Complexes / Q000235:genetics / Q000378:metabolism; D011984:Sensory Receptor Cells / Q000378:metabolism* / Q000648:ultrastructure; D015398:Signal Transduction; D058570:TOR Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: C000602135:CHORD protein, Drosophila; D002352:Carrier Proteins; D029721:Drosophila Proteins; D007328:Insulin; D018832:Molecular Chaperones; D046912:Multiprotein Complexes; C570998:TORC1 protein complex, Drosophila; D014157:Transcription Factors; D000076225:Mechanistic Target of Rapamycin Complex 2; D058570:TOR Serine-Threonine Kinases