title: C. elegans sym-1 is a downstream target of the hunchback-like-1 developmental timing transcription factor.
abstract: In the nematode Caenorhabditis elegans, the let-7 microRNA (miRNA) and its family members control the timing of key developmental events in part by directly regulating expression of hunchback-like-1 (hbl-1). C. elegans hbl-1 mutants display multiple developmental timing deficiencies, including cell cycle defects during larval development. While hbl-1 is predicted to encode a transcriptional regulator, downstream targets of HBL-1 have not been fully elucidated. Here we report using microarray analysis to uncover genes downstream of HBL-1. We established a transgenic strain that overexpresses hbl-1 under the control of a heat shock promoter. Heat shock-induced hbl-1 overexpression led to retarded hypodermal structures at the adult stage, opposite to the effect seen in loss of function (lf) hbl-1 mutants. The microarray screen identified numerous potential genes that are upregulated or downregulated by HBL-1, including sym-1, which encodes a leucine-rich repeat protein with a signal sequence. We found an increase in sym-1 transcription in the heat shock-induced hbl-1 overexpression strain, while loss of hbl-1 function caused a decrease in sym-1 expression levels. Furthermore, we found that sym-1(lf) modified the hypodermal abnormalities in hbl-1 mutants. Given that SYM-1 is a protein secreted from hypodermal cells to the surrounding cuticle, we propose that the adult-specific cuticular structures may be under the temporal control of HBL-1 through regulation of sym-1 transcription.
authors.affiliation: Initiative for the Promotion of Young Scientists' Independent Research, Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki, Japan.
authors.forename: Ryusuke
authors.initials: R
authors.lastname: Niwa
authors.forename: Kazumasa
authors.initials: K
authors.lastname: Hada
authors.forename: Kouichi
authors.initials: K
authors.lastname: Moliyama
authors.forename: Ryosuke L
authors.initials: RL
authors.lastname: Ohniwa
authors.forename: Yi-Meng
authors.initials: YM
authors.lastname: Tan
authors.forename: Katherine
authors.initials: K
authors.lastname: Olsson-Carter
authors.forename: Woo
authors.initials: W
authors.lastname: Chi
authors.forename: Valerie
authors.initials: V
authors.lastname: Reinke
authors.forename: Frank J
authors.initials: FJ
authors.lastname: Slack
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D019521:Body Patterning / Q000235:genetics*; D017173:Caenorhabditis elegans / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D029742:Caenorhabditis elegans Proteins / Q000235:genetics* / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D020405:Dermis / Q000002:abnormalities / Q000166:cytology / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental / Q000235:genetics; D009154:Mutation / Q000235:genetics; D020411:Oligonucleotide Array Sequence Analysis; D050436:Regulatory Elements, Transcriptional / Q000235:genetics; D015398:Signal Transduction / Q000502:physiology; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism
chemical_list: D029742:Caenorhabditis elegans Proteins; D004268:DNA-Binding Proteins; D014157:Transcription Factors; C121973:Sym-1 protein, C elegans; C474486:hbl-1 protein, C elegans