RESUMO
A reduction-of-function mutation in ect-2 was isolated as a suppressor of the Multivulva phenotype of a lin-31 mutation. Analysis using markers indicates that this mutation causes defects in both the cytokinesis and migration of epidermal P cells, phenotypes similar to those caused by expressing a rho-1 dominant-negative construct. ect-2 encodes the Caenorhabditis elegans orthologue of the mouse Ect2 and Drosophila Pebble that function as guanine nucleotide exchange factors (GEFs) for Rho GTPases. The ect-2Colon, two colonsGFP reporter is expressed in embryonic cells and P cells. RNA interference of ect-2 causes sterility and embryonic lethality, in addition to the P-cell defects. We have determined the lesions of two ect-2 alleles, and described their differences in phenotypes in specific tissues. We propose a model in which ECT-2GEF not only activates RHO-1 for P-cell cytokinesis, but also collaborates with UNC-73GEF and at least two Rac proteins to regulate P-cell migration.
Assuntos
Caenorhabditis elegans/genética , Citocinese , Células Epiteliais/fisiologia , Genes de Helmintos , Fatores de Troca do Nucleotídeo Guanina/fisiologia , Animais , Sequência de Bases , Caenorhabditis elegans/fisiologia , Proteínas de Caenorhabditis elegans/genética , Proteínas de Caenorhabditis elegans/fisiologia , Movimento Celular , Mapeamento Cromossômico , Cromossomos , Sequência Consenso , Feminino , Genes Reporter , Marcadores Genéticos , Proteínas de Fluorescência Verde/metabolismo , Fatores de Troca do Nucleotídeo Guanina/genética , Modelos Biológicos , Dados de Sequência Molecular , Regiões Promotoras Genéticas , Estrutura Terciária de Proteína , Fatores de Troca de Nucleotídeo Guanina Rho , Deleção de SequênciaRESUMO
Using cDNA-based array analysis combined with double-stranded RNA interference (dsRNAi), we have identified yk298h6 as a target gene of Caenorhabditis elegans TGF-beta signaling. Worms overexpressing dbl-1, a TGF-beta ligand, are 16% longer than wild type. Array analysis shows yk298h6 to be one of several genes suppressed in such worms. Disruption of yk298h6 function by dsRNAi also resulted in long worms, suggesting that it is a negative regulator of body length. yk298h6 was then mapped to, and shown to be identical to, lon-1, a known gene that affects body length. lon-1 encodes a 312 amino acid protein with a motif sequence that is conserved from plants to humans. Expression studies confirm that LON-1 is repressed by DBL-1, suggesting that LON-1 is a novel downstream component of the C.elegans TGF-beta growth regulation pathway. Consistent with this, LON-1 is expressed mainly in the larval and adult hypodermis and has dose-dependent effects on body length associated with changes in hypodermal ploidy, but not hypodermal cell proliferation.