Caenorhabditis elegans twist plays an essential role in non-striated muscle development.
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.
Corsi
A K
AK
Laboratory of Molecular Biology, NIDDK, NIH, Bethesda, MD 20892-0510, USA.
Kostas
S A
SA
Fire
A
A
Krause
M
M
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*
D015801:Helminth Proteins; D014157:Transcription Factors