title: RHGF-2 is an essential Rho-1 specific RhoGEF that binds to the multi-PDZ domain scaffold protein MPZ-1 in Caenorhabditis elegans.
abstract: RhoGEF proteins activate the Rho family of small GTPases and thus play a key role in regulating fundamental cellular processes such as cell morphology and polarity, cell cycle progression and gene transcription. We identified a Caenorhabditis elegans RhoGEF protein, RHGF-2, as a binding partner of the C. elegans multi-PDZ domain scaffold protein MPZ-1 (MUPP1 in mammals). RHGF-2 exhibits significant identity to the mammalian RhoGEFs PLEKHG5/Tech/Syx and contains a class I C-terminal PDZ binding motif (SDV) that interacts most strongly to MPZ-1 PDZ domain eight. RHGF-2 RhoGEF activity is specific to the C. elegans RhoA homolog RHO-1 as determined by direct binding, GDP/GTP exchange and serum response element-driven reporter activity. rhgf-2 is an essential gene since rhgf-2 deletion mutants do not elongate during embryogenesis and hatch as short immobile animals that arrest development. Interestingly, the expression of a functional rhgf-2::gfp transgene appears to be exclusively neuronal and rhgf-2 overexpression results in loopy movement with exaggerated body bends. Transient expression of RHGF-2 in N1E-115 neuroblastoma cells prevents neurite outgrowth similar to constitutive RhoA activation in these cells. Together, these observations indicate neuronally expressed RHGF-2 is an essential RHO-1 specific RhoGEF that binds most strongly to MPZ-1 PDZ domain eight and is required for wild-type C. elegans morphology and growth.
authors.affiliation: Department of Biological Sciences, University of Toledo, Toledo, Ohio, United States of America.
authors.forename: Li
authors.initials: L
authors.lastname: Lin
authors.forename: Thuy
authors.initials: T
authors.lastname: Tran
authors.forename: Shuang
authors.initials: S
authors.lastname: Hu
authors.forename: Todd
authors.initials: T
authors.lastname: Cramer
authors.forename: Richard
authors.initials: R
authors.lastname: Komuniecki
authors.forename: Robert M
authors.initials: RM
authors.lastname: Steven
mesh_terms: D020816:Amino Acid Motifs; D000818:Animals; D030801:Animals, Genetically Modified; D017173:Caenorhabditis elegans / Q000166:cytology / Q000201:enzymology / Q000254:growth & development / Q000378:metabolism*; D029742:Caenorhabditis elegans Proteins / Q000737:chemistry* / Q000378:metabolism*; D002352:Carrier Proteins / Q000737:chemistry* / Q000378:metabolism*; D048430:Cell Shape; D004789:Enzyme Activation; D049452:Green Fluorescent Proteins / Q000378:metabolism; D020662:Guanine Nucleotide Exchange Factors / Q000378:metabolism*; D057809:HEK293 Cells; D006801:Humans; D008124:Locomotion; D008954:Models, Biological; D009154:Mutation / Q000235:genetics; D009420:Nervous System / Q000166:cytology / Q000378:metabolism; D009474:Neurons / Q000378:metabolism; D054731:PDZ Domains; D011485:Protein Binding; D021381:Protein Transport; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D064067:Rho Guanine Nucleotide Exchange Factors; D040521:Subcutaneous Tissue / Q000378:metabolism; D020741:rho GTP-Binding Proteins / Q000378:metabolism*
chemical_list: D029742:Caenorhabditis elegans Proteins; D002352:Carrier Proteins; D020662:Guanine Nucleotide Exchange Factors; C573092:MPZ-1 protein, C elegans; C573091:RHGF-2 protein, C elegans; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; D064067:Rho Guanine Nucleotide Exchange Factors; D049452:Green Fluorescent Proteins; C560609:RHO-1 protein, C elegans; D020741:rho GTP-Binding Proteins