title: A mammalian Rho-specific guanine-nucleotide exchange factor (p164-RhoGEF) without a pleckstrin homology domain.
abstract: Rho GTPases, which are activated by specific guanine-nucleotide exchange factors (GEFs), play pivotal roles in several cellular functions. We identified a recently cloned human cDNA, namely KIAA0337, encoding a protein containing 1510 amino acids (p164). It contains a RhoGEF-specific Dbl homology (DH) domain but lacks their typical pleckstrin homology domain. The expression of the mRNA encoding p164 was found to be at least 4-fold higher in the heart than in other tissues. Recombinant p164 interacted with and induced GDP/GTP exchange at RhoA but not at Rac1 or Cdc42. p164-DeltaC and p164-DeltaN are p164 mutants that are truncated at the C- and N-termini respectively but contain the DH domain. In contrast with the full-length p164, expression of p164-DeltaC and p164-DeltaN strongly induced actin stress fibre formation and activated serum response factor-mediated and Rho-dependent gene transcription. Interestingly, p164-DeltaN2, a mutant containing the C-terminus but having a defective DH domain, bound to p164-DeltaC and suppressed the p164-DeltaC-induced gene transcription. Overexpression of the full-length p164 inhibited M(3) muscarinic receptor-induced gene transcription, whereas co-expression with Gbeta(1)gamma(2) dimers induced transcriptional activity. It is concluded that p164-RhoGEF is a Rho-specific GEF with novel structural and regulatory properties and predominant expression in the heart. Apparently, its N- and C-termini interact with each other, thereby inhibiting its GEF activity.
authors.affiliation: Institut für Pharmakologie, Universitätsklinikum Essen, Hufelandstrasse 55, Germany.
authors.forename: Ulrich
authors.initials: U
authors.lastname: Rümenapp
authors.forename: Andrea
authors.initials: A
authors.lastname: Freichel-Blomquist
authors.forename: Burkhard
authors.initials: B
authors.lastname: Wittinghofer
authors.forename: Karl H
authors.initials: KH
authors.lastname: Jakobs
authors.forename: Thomas
authors.initials: T
authors.lastname: Wieland
mesh_terms: D000595:Amino Acid Sequence; D001798:Blood Proteins / Q000737:chemistry*; D015152:Blotting, Northern; D002460:Cell Line; D003599:Cytoskeleton / Q000378:metabolism; D018076:DNA, Complementary / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation; D020662:Guanine Nucleotide Exchange Factors / Q000737:chemistry* / Q000378:metabolism*; D006801:Humans; D008856:Microscopy, Fluorescence; D008969:Molecular Sequence Data; D009206:Myocardium / Q000378:metabolism; D010750:Phosphoproteins / Q000737:chemistry*; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D012313:RNA / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D064067:Rho Guanine Nucleotide Exchange Factors; D012260:Ribonucleases / Q000378:metabolism; D015398:Signal Transduction; D013997:Time Factors; D014018:Tissue Distribution; D014158:Transcription, Genetic; D014162:Transfection
chemical_list: C577226:ARHGEF17 protein, human; D001798:Blood Proteins; D018076:DNA, Complementary; D020662:Guanine Nucleotide Exchange Factors; D010750:Phosphoproteins; D011994:Recombinant Proteins; D064067:Rho Guanine Nucleotide Exchange Factors; C039077:platelet protein P47; D012313:RNA; D012260:Ribonucleases