title: Dominant-negative Gα subunits are a mechanism of dysregulated heterotrimeric G protein signaling in human disease.
abstract: Auriculo-condylar syndrome (ACS), a rare condition that impairs craniofacial development, is caused by mutations in a G protein-coupled receptor (GPCR) signaling pathway. In mice, disruption of signaling by the endothelin type A receptor (ET(A)R), which is mediated by the G protein (heterotrimeric guanine nucleotide-binding protein) subunit Gα(q/11) and subsequently phospholipase C (PLC), impairs neural crest cell differentiation that is required for normal craniofacial development. Some ACS patients have mutations inGNAI3, which encodes Gα(i3), but it is unknown whether this G protein has a role within the ET(A)R pathway. We used a Xenopus model of vertebrate development, in vitro biochemistry, and biosensors of G protein activity in mammalian cells to systematically characterize the phenotype and function of all known ACS-associated Gα(i3) mutants. We found that ACS-associated mutations in GNAI3 produce dominant-negative Gα(i3) mutant proteins that couple to ET(A)R but cannot bind and hydrolyze guanosine triphosphate, resulting in the prevention of endothelin-mediated activation of Gα(q/11) and PLC. Thus, ACS is caused by functionally dominant-negative mutations in a heterotrimeric G protein subunit.
authors.affiliation: Department of Biochemistry, Boston University School of Medicine, Boston, MA 02118, USA.
authors.forename: Arthur
authors.initials: A
authors.lastname: Marivin
authors.affiliation: Department of Biochemistry, Boston University School of Medicine, Boston, MA 02118, USA.
authors.forename: Anthony
authors.initials: A
authors.lastname: Leyme
authors.affiliation: Department of Biochemistry, Boston University School of Medicine, Boston, MA 02118, USA.
authors.forename: Kshitij
authors.initials: K
authors.lastname: Parag-Sharma
authors.affiliation: Department of Biochemistry, Boston University School of Medicine, Boston, MA 02118, USA.
authors.forename: Vincent
authors.initials: V
authors.lastname: DiGiacomo
authors.affiliation: Department of Biochemistry, Boston University School of Medicine, Boston, MA 02118, USA.
authors.forename: Anthony Y
authors.initials: AY
authors.lastname: Cheung
authors.affiliation: Department of Biochemistry, Boston University School of Medicine, Boston, MA 02118, USA.
authors.forename: Lien T
authors.initials: LT
authors.lastname: Nguyen
authors.affiliation: Department of Medicine, Boston University School of Medicine, Boston, MA 02118, USA.
authors.forename: Isabel
authors.initials: I
authors.lastname: Dominguez
authors.affiliation: Department of Biochemistry, Boston University School of Medicine, Boston, MA 02118, USA. mgm1@bu.edu.
authors.forename: Mikel
authors.initials: M
authors.lastname: Garcia-Marcos
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D004423:Ear / Q000002:abnormalities*; D004427:Ear Diseases / Q000235:genetics* / Q000378:metabolism; D019206:GTP-Binding Protein alpha Subunits, Gi-Go / Q000235:genetics* / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D015151:Immunoblotting; D008856:Microscopy, Fluorescence; D008957:Models, Genetic; D009154:Mutation; D011485:Protein Binding; D044022:Receptor, Endothelin A / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction / Q000235:genetics*; D020798:Two-Hybrid System Techniques; D014982:Xenopus laevis
chemical_list: D044022:Receptor, Endothelin A; D006160:Guanosine Triphosphate; D019206:GTP-Binding Protein alpha Subunits, Gi-Go