Affinage

GNAI3

Guanine nucleotide-binding protein G(i) subunit alpha-3 · UniProt P08754

Length
354 aa
Mass
40.5 kDa
Annotated
2026-06-10
22 papers in source corpus 12 papers cited in narrative 12 extracted findings
Cross-family judge vs UniProt: Affinage preferred faithfulness: 6/6 claims corpus-supported (100%)

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

GNAI3 encodes Gαi3, an inhibitory heterotrimeric G-protein α subunit that transduces G-protein-coupled receptor signals into the control of cell migration, differentiation, and inflammatory signaling (PMID:23977324, PMID:30836096). In the immune system, Gαi3 acts redundantly with Gαi2 to relay chemoattractant receptor signals in B lymphocytes; loss of both subunits renders B cells refractory to chemokine stimulation and disrupts their compartmentalization in mucosal sites, splenic marginal zones, and lymph nodes (PMID:23977324). Gαi3 also restrains inflammatory tumorigenesis: together with Gαi1 it blocks IL6-driven activation of NF-κB (via JAK2–TRAF6–TAK1–IKKβ) and STAT3, limiting myeloid-derived suppressor cell expansion in colitis-associated cancer (PMID:30836096), and Gαi3 expression suppresses LPS-induced NF-κB/NLRP3 inflammasome signaling (PMID:38636252). In skeletal and dental development, Gαi3 promotes osteoblast and odontoblast proliferation, migration, and osteogenic/odontogenic differentiation through the JNK–p38 MAPK axis (PMID:34803495), functioning as a transcriptional target directly activated by GATA4 (PMID:28484278) and post-transcriptionally repressed by miR-222, miR-24-2-5p, and stabilized by Lin28A (PMID:25444921, PMID:34803495, PMID:38636252). Gαi3 cooperates with regulator-of-G-protein-signaling proteins, partnering with RGS19 to enable zVAD-induced autophagy (PMID:24751948) and with RGS14 to sustain spermatogonial stem cell proliferation via a PLPP2/MAPK axis (PMID:40352663). Missense mutations in the GDP/GTP-binding region of GNAI3 cause auriculocondylar syndrome, acting through a dominant-negative mechanism that disrupts EDN1–DLX5/DLX6 signaling required for mandibular specification (PMID:22560091, PMID:25026904).

Mechanistic history

Synthesis pass · year-by-year structured walk · 9 steps
  1. 2012 Medium

    Established GNAI3 as a disease gene by linking missense mutations to auriculocondylar syndrome and placing Gαi3 within the EDN1-DLX5/DLX6 craniofacial patterning pathway.

    Evidence Exome sequencing, protein-structure modeling of catalytic sites, and downstream expression assays in patient osteoblasts

    PMID:22560091

    Open questions at the time
    • No in vitro biochemical demonstration of altered nucleotide binding
    • Dominant-negative mechanism inferred from modeling, not reconstituted
  2. 2013 High

    Defined a physiological role for Gαi3 in immune cell trafficking, showing it acts redundantly with Gαi2 to transduce chemoattractant signals required for B cell positioning.

    Evidence Conditional Gnai2/Gnai3 double-knockout mouse, flow cytometry, chemokine responsiveness assays

    PMID:23977324

    Open questions at the time
    • Redundancy with Gαi2 obscures Gαi3-specific contribution
    • Receptor partners not individually mapped
  3. 2014 Medium

    Identified post-transcriptional and protein-interaction layers controlling Gαi3, linking it to cancer cell motility, autophagy, and a tumor-suppressive output.

    Evidence Transwell assays with miR-222 3'UTR targeting in HCC; Co-IP of RGS19-GNAI3 with shRNA autophagy/cell-death readouts in L929; RIP assay for Lin28A mRNA stabilization with osteogenic readouts

    PMID:24751948 PMID:25444921 PMID:38636252

    Open questions at the time
    • Mechanism of Gαi3 in autophagy beyond RGS19 association unclear
    • Lin28A study published later; mRNA-regulation generality untested
  4. 2014 Low

    Refined the structural basis of ACS variants, showing all reported residues cluster in G1/G4 nucleotide-binding boxes consistent with dominant-negative loss of GTP binding.

    Evidence Sanger sequencing and structural modeling of GDP/GTP-binding motifs

    PMID:25026904

    Open questions at the time
    • Structural modeling only, no biochemical validation of nucleotide-binding defect
    • Dominant-negative effect not functionally demonstrated
  5. 2016 Low

    Connected Gαi3 to OA1 GPCR signaling in retinal pigment epithelium controlling melanosomal biogenesis.

    Evidence OA1-specific Gαi3 activation cited as prior work; GNAI3 NGS screening in ocular albinism patients

    PMID:27607449

    Open questions at the time
    • Primary OA1-Gαi3 activation data not provided in this study
    • No causative GNAI3 variant established in patients
  6. 2017 Medium

    Placed GNAI3 in a transcriptional circuit by showing GATA4 directly activates its promoter to drive odontogenic/osteogenic differentiation.

    Evidence Dual-luciferase reporter and ChIP for GATA4 promoter binding; shRNA GNAI3 knockdown in SCAPs; conditional knockout mouse

    PMID:28484278

    Open questions at the time
    • Downstream effectors of Gαi3 in differentiation not defined here
    • Single-lab finding
  7. 2019 High

    Demonstrated a tumor-suppressive immunoregulatory function, with Gαi1/3 blocking IL6-driven NF-κB and STAT3 signaling to limit colitis-associated tumorigenesis.

    Evidence GNAI1/3 double-knockout mouse, immunoprecipitation, immunoblot, flow cytometry, anti-IL6 rescue

    PMID:30836096

    Open questions at the time
    • Direct molecular target of Gαi3 within the IL6 cascade not pinpointed
    • Relative contributions of Gαi1 vs Gαi3 not separated
  8. 2021 Medium

    Mapped Gαi3 expression across immune and inner-ear cell types and confirmed its osteogenic role and miRNA control via a conserved zebrafish model.

    Evidence Gnai3-iresGFP reporter mouse with flow cytometry/immunofluorescence; dual-luciferase miR-24-2-5p targeting; JNK/p38 Western blot; zebrafish morpholino with mRNA rescue

    PMID:34253772 PMID:34803495

    Open questions at the time
    • Functional role of inner-ear expression untested
    • Receptor upstream of JNK-p38 activation not identified
  9. 2025 Medium

    Extended Gαi3's RGS partnerships to reproductive biology, showing RGS14-Gαi3 interaction sustains spermatogonial stem cell proliferation through a PLPP2/MAPK axis.

    Evidence Reciprocal Co-IP of RGS14-GNAI3, shRNA knockdown, RNA-seq, PLPP2 overexpression rescue

    PMID:40352663

    Open questions at the time
    • Direction of regulation between RGS14 and Gαi3 not fully resolved
    • PLPP2 regulatory link mechanistically incomplete

Open questions

Synthesis pass · forward-looking unresolved questions
  • How a single Gαi3 subunit is selectively coupled to distinct receptors and effectors across immune, skeletal, reproductive, and pigmentary contexts, and the biochemical basis of its dominant-negative disease variants, remains unresolved.
  • No reconstituted biochemistry of ACS mutant nucleotide handling
  • Receptor-specific coupling determinants undefined
  • Distinction of Gαi3-specific vs redundant Gαi functions incomplete

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0060089 molecular transducer activity 3 GO:0003924 GTPase activity 2
Localization
GO:0005886 plasma membrane 2
Pathway
R-HSA-1266738 Developmental Biology 3 R-HSA-162582 Signal Transduction 3 R-HSA-168256 Immune System 2
Partners
GNAI1GNAI2OA1RGS14RGS19

Evidence

Reading pass · 12 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2012 GNAI3 missense mutations in auriculocondylar syndrome (ACS) disrupt the catalytic/GDP-GTP binding site of the protein, and functional studies in cultured osteoblasts from ACS probands showed significant reduction in downstream DLX5 and DLX6 expression, placing GNAI3 as a core signaling molecule in the EDN1-DLX5/DLX6 pathway regulating mandibular specification. Exome sequencing identifying mutations, protein-structure modeling of catalytic sites, functional gene expression assays in cultured osteoblasts from probands American journal of human genetics Medium 22560091
2014 GNAI3 variants in ACS cluster in the GDP/GTP-binding region (G1 and G4 boxes), and structural modeling of all five reported ACS-associated GNAI3 residues indicates they all disrupt guanine nucleotide binding, consistent with a dominant negative mechanism. Sanger sequencing, protein structural modeling of GDP/GTP-binding motifs European journal of human genetics : EJHG Low 25026904
2014 GNAI3 inhibits hepatocellular carcinoma (HCC) cell migration and invasion, as demonstrated by transwell assays following GNAI3 manipulation; miR-222 directly binds the GNAI3 mRNA 3'UTR and decreases GNAI3 protein expression, providing a post-transcriptional regulatory mechanism. Transwell migration/invasion assays with GNAI3 overexpression/knockdown; miR-222 target prediction confirmed by experimental screening and mRNA binding Cancer letters Medium 25444921
2014 GNAI3 (Gαi3) is required for zVAD-induced autophagy in L929 cells, and this autophagy is required for zVAD-induced TNF production; GNAI3 was identified as a partner of RGS19 (itself identified as a RIP3-interacting protein), and shRNA knockdown of GNAI3 suppressed zVAD-induced but not TNF-induced cell death. Co-immunoprecipitation identifying RGS19-RIP3 and RGS19-GNAI3 interactions; shRNA knockdown of GNAI3 with cell death and autophagy readouts PloS one Medium 24751948
2013 Gαi3 (encoded by Gnai3), together with Gαi2, is required for B lymphocyte chemoattractant receptor signaling; B cells lacking both Gαi2 and Gαi3 are refractory to chemokine stimulation, fail to populate mucosal sites, splenic marginal zones, and lymph nodes, and cause disrupted lymphoid organ architecture with a hyper-IgM-like syndrome. Conditional knockout of Gnai2 and Gnai3 in B cells (mouse genetic model), flow cytometry, chemokine responsiveness assays PloS one High 23977324
2019 GNAI1 and GNAI3 suppress colitis-associated tumorigenesis by blocking IL6 signaling; in the absence of GNAI1/3, IL6 activates NF-κB via JAK2-TRAF6-TAK1-CHUK/IKKβ and STAT3 via JAK2, resulting in increased GNAI2, IL6ST (GP130), and NOS2 expression and MDSC expansion. Immunoprecipitation of colon tumor tissues and MDSCs demonstrated interactions of GNAI1 and GNAI3 with proteins in the IL6 signaling pathway. Double-knockout mouse model (GNAI1/3 DKO), immunoprecipitation, immunoblot, flow cytometry, anti-IL6 antibody rescue experiment Gastroenterology High 30836096
2017 GATA4 directly binds the GNAI3 promoter and transcriptionally activates GNAI3 expression; GATA4 deletion reduces GNAI3 levels in dental papilla cells, and GNAI3 knockdown itself decreases odontogenic/osteogenic differentiation of stem cells of dental apical papilla (SCAPs). Dual-luciferase reporter assay and ChIP assay confirming GATA4 binding to GNAI3 promoter; shRNA knockdown of GNAI3 with osteogenic differentiation readouts in SCAPs; conditional knockout mouse model Scientific reports Medium 28484278
2021 Mir24-2-5p directly binds the Gnai3 3'UTR and negatively regulates Gnai3 expression; Gnai3 promotes osteoblast precursor cell proliferation, migration, osteogenic differentiation, and mineralization, and acts through activation of the JNK-p38 MAPK signaling axis. In zebrafish, gnai3 morpholino knockdown recapitulated mandibular/cartilage developmental defects, partially rescued by gnai3 mRNA injection. Dual-luciferase reporter assay for miRNA-target interaction; shRNA knockdown of Gnai3; Western blot for p-JNK and p-p38; zebrafish morpholino knockdown with phenotypic rescue; osteogenic differentiation assays International journal of biological sciences Medium 34803495
2016 GNAI3 (Gαi3) is specifically activated by the OA1 G-protein coupled receptor in the retinal pigment epithelium and participates in the OA1 transduction pathway regulating melanosomal biogenesis. Functional signaling studies demonstrating Oa1-specific activation of Gαi3 (referenced as prior work); GNAI3 gene screening in OA patients by next-generation sequencing PloS one Low 27607449
2014 Lin28A stabilizes GNAI3 mRNA, as demonstrated by RIP assay confirming Lin28A binding to GNAI3 mRNA, and Lin28A knockdown reduced GNAI3 expression; GNAI3 overexpression suppresses LPS-induced NF-κB/NLRP3 inflammasome pathway activation, inflammation, and apoptosis in periodontal ligament stem cells, and promotes osteogenic differentiation. RIP assay for Lin28A-GNAI3 mRNA interaction; GNAI3 overexpression with Western blot for NF-κB/NLRP3 pathway proteins; ELISA for cytokines; ALP and ARS staining for osteogenic differentiation Archives of oral biology Medium 38636252
2025 RGS14 physically interacts with GNAI3 to coordinately regulate spermatogonial stem cell (SSC) proliferation and PLPP2 expression; RGS14 knockdown suppresses SSC proliferation and induces apoptosis, phenotypes that are linked to GNAI3 and the RGS14-GNAI3-PLPP2 axis through MAPK signaling. Protein-protein interaction assays and co-immunoprecipitation of RGS14-GNAI3; shRNA knockdown of RGS14; RNA-sequencing; PLPP2 overexpression rescue Frontiers in cell and developmental biology Medium 40352663
2021 Gαi3 is expressed in B cells, T cells, macrophages, granulocytes, platelets, and in the inner ear (Deiter's cells and first row of Hensen's cells in the organ of Corti), as determined by a Gnai3-iresGFP reporter mouse using flow cytometry and immunofluorescence. Gnai3-iresGFP knock-in reporter mouse; flow cytometry with cell-type specific surface markers; immunofluorescence staining of inner ear Scientific reports Medium 34253772

Source papers

Stage 0 corpus · 22 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2019 GNAI1 and GNAI3 Reduce Colitis-Associated Tumorigenesis in Mice by Blocking IL6 Signaling and Down-regulating Expression of GNAI2. Gastroenterology 80 30836096
2012 A human homeotic transformation resulting from mutations in PLCB4 and GNAI3 causes auriculocondylar syndrome. American journal of human genetics 77 22560091
2014 GNAI3 inhibits tumor cell migration and invasion and is post-transcriptionally regulated by miR-222 in hepatocellular carcinoma. Cancer letters 36 25444921
2013 The loss of Gnai2 and Gnai3 in B cells eliminates B lymphocyte compartments and leads to a hyper-IgM like syndrome. PloS one 26 23977324
2017 Role of GATA binding protein 4 (GATA4) in the regulation of tooth development via GNAI3. Scientific reports 25 28484278
2014 Novel variants in GNAI3 associated with auriculocondylar syndrome strengthen a common dominant negative effect. European journal of human genetics : EJHG 24 25026904
2021 Mir24-2-5p suppresses the osteogenic differentiation with Gnai3 inhibition presenting a direct target via inactivating JNK-p38 MAPK signaling axis. International journal of biological sciences 17 34803495
2014 Regulator of G-protein signaling 19 (RGS19) and its partner Gα-inhibiting activity polypeptide 3 (GNAI3) are required for zVAD-induced autophagy and cell death in L929 cells. PloS one 12 24751948
1996 GNAI3, GNAT2, AMPD2, GSTM are clustered in 120 kb of Chinese hamster chromosome 1q. Mammalian genome : official journal of the International Mammalian Genome Society 11 8662225
1994 The highly conserved Chinese hamster GNAI3 gene maps less than 60 kb from the AMPD2 gene and lacks the intronic U6 snRNA present in its human counterpart. Genomics 9 7698751
2021 A novel missense variant of the GNAI3 gene and recognisable morphological characteristics of the mandibula in ARCND1. Journal of human genetics 7 33723370
1999 Initiation of DNA replication at the Chinese hamster origin oriGNAI3 relies on local sequences and/or chromatin structures, but not on transcription of the nearby GNAI3 gene. Nucleic acids research 7 10075990
2020 Novel CpG-SNPs in the gastric acid secretion pathway GNAI3 and susceptibility to gastric cancer. Gene 6 32032744
2024 GNAI3 mediated by Lin28A regulates lipopolysaccharide-induced inflammation and osteogenic differentiation in periodontal stem cells by mediating the NF-κB/NLRP3 inflammasome pathway. Archives of oral biology 5 38636252
2021 Prenatal diagnosis of auriculocondylar syndrome with a novel missense variant of GNAI3: a case report. BMC pregnancy and childbirth 5 34789173
2020 Downregulation of GNAI3 Promotes the Pathogenesis of Methionine/Choline-Deficient Diet-Induced Nonalcoholic Fatty Liver Disease. Gut and liver 5 31694365
2023 Pilocytic astrocytoma harboring a novel GNAI3-BRAF fusion. Neuropathology : official journal of the Japanese Society of Neuropathology 2 36786200
2021 Analyses of Gnai3-iresGFP reporter mice reveal unknown Gαi3 expression sites. Scientific reports 2 34253772
2016 GNAI3: Another Candidate Gene to Screen in Persons with Ocular Albinism. PloS one 2 27607449
2024 Novel GNAI3 mutation in a Chinese family with auriculocondylar syndrome and treatment of severe dentofacial deformities: a 5-year follow-up case report. BMC oral health 1 39014351
2025 RGS14 binds to GNAI3 and regulates the proliferation and apoptosis of human spermatogonial stem cells by affecting PLPP2 expression and MAPK signaling. Frontiers in cell and developmental biology 0 40352663
2025 LncRNA SNHG29 Suppresses Epithelial Ovarian Cancer Cell Invasion and Migration via miR-20b-3p/GNAI3 Axis Regulation. Cancer genetics 0 41202710

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