Molecular characterization of HLH-17, a C. elegans bHLH protein required for normal larval development.
The basic helix-loop-helix (bHLH) transcription factor family regulates numerous developmental events in eukaryotic cells. In the model system, C. elegans, thirty-seven bHLH proteins have been identified via genome-wide sequence analysis and fourteen have been genetically characterized to date. These proteins influence cell fate specification of neural lineages and differentiation of myogenic lineages and have distinct roles in somatic gonadogenesis. We report here on the molecular characterization of HLH-17, a protein whose putative bHLH domain is homologous to the mammalian bHLH proteins BETA3 and bHLHB5. The gene hlh-17 is transcriptionally active at all developmental stages, with the highest steady state accumulation of hlh-17 mRNA during embryogenesis. An upstream hlh-17 sequence drives expression of GFP in the sheath cells of the cephalic sensilla. Finally, animals that are defective in HLH-17 via RNAi display egg-laying defects, while those carrying null mutations in hlh-17 do not develop beyond the L2 stage and are less attracted to potassium and sodium ions. We propose that hlh-17 affects the ability of C. elegans to respond to food cues, with possible downstream effects on insulin-signaling genes involved in the normal development and reproductive viability of the worm.
McMiller
Tracee L
TL
Morgan State University, Department of Biology, Richard N. Dixon Science Research Center, 1700 E. Coldspring Lane, Baltimore, MD 21251, USA.
Johnson
Casonya M
CM
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D051792:Basic Helix-Loop-Helix Proteins; D017173:Caenorhabditis elegans / Q000235:genetics* / Q000254:growth & development; D029742:Caenorhabditis elegans Proteins / Q000235:genetics*; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics*; D018507:Gene Expression Regulation, Developmental; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D006257:Head / Q000294:innervation; D007814:Larva / Q000235:genetics / Q000254:growth & development; D008969:Molecular Sequence Data; D009154:Mutation; D009474:Neurons / Q000166:cytology / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000235:genetics; D034622:RNA Interference; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D014157:Transcription Factors / Q000235:genetics*
D051792:Basic Helix-Loop-Helix Proteins; D029742:Caenorhabditis elegans Proteins; D018076:DNA, Complementary; D004268:DNA-Binding Proteins; D049452:Green Fluorescent Proteins; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors; C504333:HLH-17 protein, C elegans