The Caenorhabditis elegans homolog of FGD1, the human Cdc42 GEF gene responsible for faciogenital dysplasia, is critical for excretory cell morphogenesis.

Gao J, Estrada L, Cho S, Ellis RE, Gorski JL
Hum Mol Genet. 2001 10 (26): 3049-62

PMID: 11751687 · DOI:10.1093/hmg/10.26.3049

FGD1 mutations result in faciogenital dysplasia, an X-linked human disease that affects skeletogenesis. FGD1 encodes a guanine nucleotide exchange factor (GEF) that specifically activates the Rho GTPase Cdc42. To gain insight into the function of FGD1, we have isolated and characterized fgd-1, the Caenorhabditis elegans homolog of the human FGD1 gene. Comparative sequence analyses show that fgd-1 and FGD1 share a similar structural organization and a high degree of sequence identity throughout shared signaling domains. In nematodes, interference with fgd-1 expression results in excretory cell abnormalities and cystic dilation of the excretory cell canals. Molecular lesions associated with two exc-5 alleles affect the fgd-1 gene, and fgd-1 transgenic expression rescues the Exc-5 phenotype. Together, these data confirm that the fgd-1 transcript corresponds to the exc-5 gene. Transgenic expression studies show that fgd-1 has a limited pattern of expression that is confined to the excretory cell during development, a finding that suggests that the C.elegans FGD-1 protein might function in a cell autonomous manner. Serial observations indicate that fgd-1 mutations lead to developmental excretory cell abnormalities that cause cystic dilation and interfere with canal process extension. Based on these data, we conclude that fgd-1 is the C.elegans homolog of the human FGD1 gene, a new member of the FGD1-related family of RhoGEF genes, and that fgd-1 plays a critical role in excretory cell morphogenesis and cellular organization.

MeSH Terms (20)

Amino Acid Sequence Animals Blotting, Northern Caenorhabditis elegans Caenorhabditis elegans Proteins cdc42 GTP-Binding Protein Down-Regulation Facial Bones Guanine Nucleotide Exchange Factors Helminth Proteins Humans Kidney Molecular Sequence Data Morphogenesis Mutation Polymerase Chain Reaction Proteins Sequence Homology Syndrome Urogenital Abnormalities

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