title: Caenorhabditis elegans twist plays an essential role in non-striated muscle development.
abstract: The basic helix-loop-helix (bHLH) transcription factor Twist plays a role in mesodermal development in both invertebrates and vertebrates. In an effort to understand the role of the unique Caenorhabditis elegans Twist homolog, hlh-8, we analyzed mesodermal development in animals with a deletion in the hlh-8 locus. This deletion was predicted to represent a null allele because the HLH domain is missing and the reading frame for the protein is disrupted. Animals lacking CeTwist function were constipated and egg-laying defective. Both of these defects were rescued in transgenic mutant animals expressing wild-type hlh-8. Observing a series of mesoderm-specific markers allowed us to characterize the loss of hlh-8 function more thoroughly. Our results demonstrate that CeTwist performs an essential role in the proper development of a subset of mesodermal tissues in C. elegans. We found that CeTwist was required for the formation of three out of the four non-striated enteric muscles born in the embryo. In contrast, CeTwist was not required for the formation of the embryonically derived striated muscles. Most of the post-embryonic mesoderm develops from a single lineage. CeTwist was necessary for appropriate patterning in this lineage and was required for expression of two downstream target genes, but was not required for the expression of myosin, a marker of differentiation. Our results suggest that mesodermal patterning by Twist is an evolutionarily conserved function.
authors.affiliation: Laboratory of Molecular Biology, NIDDK, NIH, Bethesda, MD 20892-0510, USA.
authors.forename: A K
authors.initials: AK
authors.lastname: Corsi
authors.forename: S A
authors.initials: SA
authors.lastname: Kostas
authors.forename: A
authors.initials: A
authors.lastname: Fire
authors.forename: M
authors.initials: M
authors.lastname: Krause
mesh_terms: D000818:Animals; D017173:Caenorhabditis elegans / Q000196:embryology*; D019070:Cell Lineage; D005260:Female; D020868:Gene Silencing; D018257:Helix-Loop-Helix Motifs; D015801:Helminth Proteins / Q000235:genetics / Q000502:physiology*; D018482:Muscle, Skeletal / Q000196:embryology; D009130:Muscle, Smooth / Q000166:cytology / Q000196:embryology*; D016296:Mutagenesis; D010058:Oviposition / Q000502:physiology; D010641:Phenotype; D014157:Transcription Factors / Q000235:genetics / Q000502:physiology*
chemical_list: D015801:Helminth Proteins; D014157:Transcription Factors