{"gene":"GNAI2","run_date":"2026-06-10T01:55:21","timeline":{"discoveries":[{"year":2005,"finding":"GNAI2 (Gαi2) is required for B lymphocyte entry into lymph nodes via high endothelial venules and for normal motility within lymph node follicles. Gnai2-/- B cells enter lymph nodes poorly and move more slowly than wild-type B cells, and respond poorly to chemokines, demonstrating that Gαi1 and Gαi3 cannot compensate for loss of Gαi2 in this context.","method":"Intravital microscopy of adoptively transferred B cells from Gnai2-/- mice; chemokine response assays; genetic knockout with defined cellular phenotype","journal":"Immunity","confidence":"High","confidence_rationale":"Tier 2 / Strong — direct intravital imaging with adoptive transfer, Gnai2-/- genetic model, defined chemotaxis defect, replicated by multiple subsequent studies","pmids":["15780991"],"is_preprint":false},{"year":2006,"finding":"RGS proteins negatively regulate Gαi2 signaling in vivo. A G184S knock-in mutation in Gnai2 that blocks RGS protein binding produces a pleiotropic phenotype (enlarged spleen, elevated neutrophils, cardiac hypertrophy, shortened long bones, behavioral hyperactivity, reduced viability), demonstrating the essential role of RGS-mediated GTPase acceleration at Gαi2 across multiple organ systems.","method":"Genomic knock-in of RGS-insensitive G184S Gnai2 allele; phenotypic characterization of homozygous and heterozygous mice","journal":"Molecular and cellular biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — genomic knock-in with precise mutation blocking RGS binding, multi-organ phenotype in two zygosity states, replicated in follow-up metabolic study","pmids":["16943428"],"is_preprint":false},{"year":2007,"finding":"GNAI2 (Gαi2) is essential for T lymphocyte chemokine receptor signaling. Gnai2-/- CD4 and CD8 T cells show profound defects in chemokine-induced intracellular calcium mobilization, chemotaxis, and lymph node homing. Intravital imaging showed Gnai2-/- CD4 T cells accumulate at the cortical ridge and fail to access the paracortex, lacking amoeboid movements and active membrane projections.","method":"Intravital imaging of Gnai2-/- T cells; chemotaxis assays; calcium mobilization assays; adoptive transfer homing assays","journal":"Journal of immunology","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (imaging, calcium flux, chemotaxis, in vivo homing) in genetic knockout model","pmids":["17579064"],"is_preprint":false},{"year":2007,"finding":"RGS proteins and Gαi2 signaling regulate insulin sensitivity, glucose metabolism, and body weight. Homozygous Gαi2(G184S) knock-in mice are resistant to diet-induced obesity on a high-fat diet and are protected from insulin resistance, associated with increased energy expenditure. Both male and female G184S mice show enhanced insulin sensitivity and glucose tolerance.","method":"RGS-insensitive G184S Gnai2 knock-in mice on high-fat diet; body composition analysis; glucose/insulin tolerance tests; energy expenditure measurement","journal":"Diabetes","confidence":"High","confidence_rationale":"Tier 2 / Strong — genomic knock-in model, multiple metabolic phenotype readouts, builds on same validated allele from prior Huang et al. study","pmids":["17928396"],"is_preprint":false},{"year":2010,"finding":"The level of Gnai2 expression is a critical determinant of chemokine receptor signaling output and secondary lymphoid organ organization. Loss of a single Gnai2 allele reduces CCL19-triggered chemotaxis. Gnai2 is required for proper marginal zone B cell development, splenic architecture, lymphoid follicle size, germinal center morphology, and alignment of MOMA-1+ macrophages and MAdCAM-1+ endothelial cells along marginal zone sinuses.","method":"Mice with varying numbers of intact alleles of Ccr7, Rgs1, Gnai2, and Gnai3; chemotaxis assays; histological analysis of splenic architecture","journal":"Genes and immunity","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic dosage series with multiple readouts, single lab","pmids":["20508603"],"is_preprint":false},{"year":2013,"finding":"Combined loss of Gαi2 and Gαi3 in B cells eliminates B cell compartments at mucosal sites, splenic marginal zones, and lymph nodes, causes partial block in splenic follicular B cell development, disrupts lymphoid organ architecture, and produces a hyper-IgM-like syndrome. B cells lacking both subunits are refractory to chemokine stimulation and poorly responsive to antigen receptor engagement.","method":"B cell-specific conditional double knockout of Gnai2 and Gnai3; flow cytometry; histology; chemokine stimulation assays; immunoglobulin analysis","journal":"PloS one","confidence":"High","confidence_rationale":"Tier 2 / Strong — conditional double knockout with multiple orthogonal readouts (chemotaxis, histology, flow cytometry, immunoglobulin levels)","pmids":["23977324"],"is_preprint":false},{"year":2006,"finding":"A -318 C>G SNP in the GNAI2 promoter impairs transcriptional activity by altering transcription factor binding specificity: the G allele binds Sp1 (confirmed by supershift with anti-Sp1 antibody), while the C allele binds YY1. The G allele has 2.5-fold reduced transcriptional activity in transfected HEK293 cells and is associated with higher systolic blood pressure.","method":"Electrophoretic mobility shift assay (EMSA) with competition; supershift with anti-Sp1 and anti-YY1 antibodies; luciferase reporter transfection in HEK293 cells","journal":"Journal of the American Society of Nephrology","confidence":"Medium","confidence_rationale":"Tier 1–2 / Moderate — EMSA with supershift and reporter assay provide mechanistic evidence for transcription factor binding, single lab","pmids":["16565233"],"is_preprint":false},{"year":2010,"finding":"GNAI2 is a direct target of miR-138 in tongue squamous cell carcinoma cells. miR-138 directly binds two candidate sequences in the 3'-UTR of GNAI2 mRNA (confirmed by luciferase reporter assay). Knockdown of miR-138 increases GNAI2 at mRNA and protein levels; ectopic miR-138 reduces GNAI2 expression and leads to reduced proliferation, cell cycle arrest, and apoptosis.","method":"Luciferase reporter assay; qPCR; Western blot; genome-wide expression profiling; miR-138 transfection/knockdown in TSCC cells","journal":"Human genetics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — luciferase reporter validation of direct 3'-UTR targeting plus phenotypic readouts, single lab","pmids":["21079996"],"is_preprint":false},{"year":2019,"finding":"GNAI2 in CD11c+ dendritic cells promotes colitis-associated tumorigenesis. GNAI1 and GNAI3 suppress colonic tumor development by blocking IL6 signaling; their absence leads to increased GNAI2 expression. IL6 activates GNAI2 expression via JAK2-mediated NF-κB (through TRAF6-TAK1-CHUK/IKKβ) and STAT3 signaling pathways. Conditional disruption of Gnai2 in CD11c+ cells of GNAI1/3 double-knockout mice prevented NF-κB and STAT3 activation and normalized DC and MDSC numbers.","method":"Conditional knockout mice; immunoprecipitation; immunoblot; flow cytometry; IL6 antibody blockade; conditional Gnai2 disruption in CD11c+ cells; cytokine ELISA","journal":"Gastroenterology","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple genetic models (single KO, double KO, conditional KO), reciprocal immunoprecipitation, functional rescue experiments, multiple orthogonal methods","pmids":["30836096"],"is_preprint":false},{"year":2025,"finding":"GPR75 signals through GNAI2 to regulate hepatic lipid metabolism. Depletion of hepatic Gpr75 activates the GNAI2-cAMP-PKA signaling pathway, reducing SREBP-1c maturation and de novo lipogenesis. GPR75 overexpression in hepatocytes exacerbates diet-induced MASH and liver fibrosis, while its deficiency is protective.","method":"Hepatocyte-specific Gpr75 knockout and overexpression in mice; diet-induced MASH model; signaling pathway analysis (cAMP-PKA, SREBP-1c)","journal":"Hepatology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vivo genetic models with defined signaling pathway, single lab, abstract-level detail","pmids":["41632920"],"is_preprint":false},{"year":2023,"finding":"miR-34b-5p negatively targets Gnai2 by directly binding its 3'-UTR (validated by dual luciferase reporter assay). In fluorine-aluminum-induced neuronal apoptosis, decreased Gnai2 expression (caused by increased miR-34b-5p) suppresses the PKA/ERK/CREB signaling pathway, and inhibition of miR-34b-5p alleviates apoptosis by restoring Gnai2, PKA, ERK, and CREB expression.","method":"Dual luciferase reporter assay; miR-34b-5p agomir/antagomir transfection; Western blot; rat hippocampal neuron model and NG108-15 cell model","journal":"Environmental science and pollution research international","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct 3'-UTR targeting validated by luciferase assay, pathway placement via multiple signaling readouts, single lab","pmids":["37186186"],"is_preprint":false},{"year":2024,"finding":"S100A4 interacts with GNAI2 as a downstream binding partner (identified by co-immunoprecipitation and mass spectrometry), and S100A4 activates the MAPK signaling pathway to promote endometrial epithelial cell proliferation by targeting GNAI2. GnRH suppresses S100A4 expression, thereby inhibiting cell proliferation through the S100A4/GNAI2/MAPK pathway.","method":"Co-immunoprecipitation and mass spectrometry to identify GNAI2 as S100A4-interacting protein; overexpression/knockdown experiments; CCK-8 and EdU proliferation assays","journal":"Frontiers in veterinary science","confidence":"Medium","confidence_rationale":"Tier 2–3 / Moderate — Co-IP/MS identification of interaction plus functional overexpression/knockdown assays, single lab, sheep/mouse model","pmids":["38872805"],"is_preprint":false},{"year":2025,"finding":"TMEM100 interacts with both PRDX1 and GNAI2, disrupting the PRDX1-GNAI2 protein complex. This disruption inhibits LPS-induced NF-κB activation in pulmonary vascular endothelial cells, contributing to anti-inflammatory effects in acute lung injury.","method":"Co-immunoprecipitation; overexpression of TMEM100; LPS-induced acute lung injury model; NF-κB activation assays","journal":"bioRxiv","confidence":"Low","confidence_rationale":"Tier 3 / Weak — preprint, single Co-IP identifying complex disruption, single lab, abstract-level detail only","pmids":["bio_10.1101_2025.10.24.684325"],"is_preprint":true},{"year":2024,"finding":"GNAI2 is a direct target of miR-181a in ovine dermal papilla cells (confirmed by dual luciferase reporter assay). GNAI2 promotes proliferation and induction ability of dermal papilla cells and activates the Wnt/β-Catenin signaling pathway. miR-181a inhibits dermal papilla cell proliferation and induction ability by targeting GNAI2.","method":"Dual luciferase reporter assay; qRT-PCR; Western blot; CCK-8; EdU assay; flow cytometry; alkaline phosphatase staining","journal":"International journal of molecular sciences","confidence":"Low","confidence_rationale":"Tier 3 / Weak — ovine model (non-mammalian canonical context), single lab, luciferase validation present but Wnt pathway activation inferred without direct mechanistic dissection","pmids":["39063192"],"is_preprint":false}],"current_model":"GNAI2 encodes the Gαi2 subunit of heterotrimeric G proteins, which transduces chemoattractant receptor signals to drive lymphocyte trafficking, chemotaxis, and compartmentalization in secondary lymphoid organs; its GTPase activity is accelerated by RGS proteins (blocked by the G184S mutation), and it signals through downstream pathways including cAMP inhibition, PI3K/Akt, PKA/ERK/CREB, MAPK, and NF-κB/STAT3 to regulate immune cell function, insulin sensitivity, lipid metabolism, and cell proliferation."},"narrative":{"mechanistic_narrative":"GNAI2 encodes Gαi2, a heterotrimeric G protein α subunit that transduces chemoattractant-receptor signals to control lymphocyte trafficking and the architecture of secondary lymphoid organs [PMID:15780991, PMID:17579064]. Gαi2 is non-redundantly required for B and T cell chemokine responses: Gnai2-deficient lymphocytes home poorly to lymph nodes, show defective chemokine-induced calcium mobilization and chemotaxis, and lose the amoeboid motility needed to navigate lymphoid compartments, defects that Gαi1 and Gαi3 cannot compensate for [PMID:15780991, PMID:17579064]. Gαi2 dosage is itself a determinant of signaling output, controlling marginal zone B cell development and splenic architecture [PMID:20508603], and combined loss of Gαi2 and Gαi3 in B cells eliminates mucosal, marginal zone, and lymph node B cell compartments and produces a hyper-IgM-like syndrome [PMID:23977324]. Gαi2 signaling is negatively constrained by RGS proteins acting as GTPase-activating factors: an RGS-insensitive G184S knock-in allele yields a pleiotropic multi-organ phenotype and, metabolically, protects against diet-induced obesity and insulin resistance while increasing energy expenditure [PMID:16943428, PMID:17928396]. Downstream, Gαi2 couples receptors to discrete effector cascades — the cAMP-PKA axis controlling SREBP-1c maturation and hepatic lipogenesis downstream of GPR75 [PMID:41632920], and NF-κB/STAT3 signaling driving colitis-associated tumorigenesis in dendritic cells [PMID:30836096]. Gαi2 expression is regulated by promoter sequence variation affecting Sp1/YY1 binding [PMID:16565233] and by direct 3'-UTR targeting by miR-138 [PMID:21079996].","teleology":[{"year":2005,"claim":"Established that Gαi2 is non-redundantly required for B lymphocyte entry into and motility within lymph nodes, defining a specific physiological role for one Gαi isoform in immune cell trafficking.","evidence":"Intravital microscopy of adoptively transferred Gnai2-/- B cells with chemokine response assays","pmids":["15780991"],"confidence":"High","gaps":["Did not identify the specific chemokine receptors coupling to Gαi2","Molecular basis of isoform non-redundancy not resolved"]},{"year":2006,"claim":"Demonstrated that RGS-mediated GTPase acceleration is essential to constrain Gαi2 signaling in vivo, showing the consequences of unrestrained Gαi2 activity across multiple organ systems.","evidence":"Genomic knock-in of the RGS-insensitive G184S Gnai2 allele with phenotypic characterization in two zygosity states","pmids":["16943428"],"confidence":"High","gaps":["Did not assign individual RGS proteins to specific tissues","Did not connect organ phenotypes to specific receptor-effector circuits"]},{"year":2006,"claim":"Connected a GNAI2 promoter SNP to altered transcription factor binding and reduced expression, providing a mechanism for variation in Gαi2 levels linked to blood pressure.","evidence":"EMSA with Sp1/YY1 supershift and luciferase reporter assays in HEK293 cells","pmids":["16565233"],"confidence":"Medium","gaps":["Causal link between expression change and blood pressure not established in vivo","Single-lab association"]},{"year":2007,"claim":"Extended the chemotaxis requirement to T cells, showing Gαi2 is essential for chemokine-induced calcium flux, motility, and paracortical positioning.","evidence":"Intravital imaging, calcium mobilization, chemotaxis, and homing assays in Gnai2-/- T cells","pmids":["17579064"],"confidence":"High","gaps":["Did not map which downstream effectors mediate amoeboid movement"]},{"year":2007,"claim":"Revealed a metabolic role for RGS-Gαi2 signaling, showing that blocking RGS regulation of Gαi2 protects against diet-induced obesity and insulin resistance.","evidence":"G184S knock-in mice on high-fat diet with glucose/insulin tolerance and energy expenditure measurements","pmids":["17928396"],"confidence":"High","gaps":["Tissue source of the metabolic phenotype not localized","Receptor and effector pathway in metabolism not defined"]},{"year":2010,"claim":"Showed that Gαi2 gene dosage quantitatively tunes chemokine signaling output and is required for proper splenic marginal zone organization.","evidence":"Allelic dosage series across Ccr7, Rgs1, Gnai2, and Gnai3 with chemotaxis and splenic histology","pmids":["20508603"],"confidence":"Medium","gaps":["Single-lab study","Mechanism linking dosage to architectural changes not dissected"]},{"year":2010,"claim":"Identified post-transcriptional control of GNAI2 by miR-138 and linked its expression to proliferation and survival in carcinoma cells.","evidence":"Luciferase 3'-UTR reporter assays with miR-138 transfection/knockdown in tongue squamous cell carcinoma cells","pmids":["21079996"],"confidence":"Medium","gaps":["Downstream Gαi2 effector mediating proliferation not identified","Single-lab study"]},{"year":2013,"claim":"Demonstrated combinatorial requirement of Gαi2 and Gαi3 in B cells for compartment formation and immunoglobulin homeostasis.","evidence":"B cell-specific conditional double knockout with chemokine stimulation, histology, flow cytometry, and immunoglobulin analysis","pmids":["23977324"],"confidence":"High","gaps":["Did not separate Gαi2-specific from Gαi3-specific contributions in the double knockout"]},{"year":2019,"claim":"Placed Gαi2 in an IL6-driven NF-κB/STAT3 circuit in dendritic cells, showing it promotes colitis-associated tumorigenesis when GNAI1/3 are lost.","evidence":"Conditional knockout and double-knockout mice, immunoprecipitation, IL6 blockade, and flow cytometry","pmids":["30836096"],"confidence":"High","gaps":["Direct biochemical coupling of Gαi2 to the JAK2/NF-κB/STAT3 machinery not fully resolved"]},{"year":2023,"claim":"Linked Gαi2 to the PKA/ERK/CREB axis in neurons, where miR-34b-5p suppression of Gαi2 contributes to apoptosis.","evidence":"Dual luciferase 3'-UTR assays with miR-34b-5p agomir/antagomir and pathway Western blots in neuronal models","pmids":["37186186"],"confidence":"Medium","gaps":["Receptor upstream of Gαi2 in this context unknown","Single-lab study"]},{"year":2024,"claim":"Identified S100A4 as a physical partner that signals through Gαi2 to activate MAPK and drive endometrial epithelial proliferation.","evidence":"Co-IP/mass spectrometry plus overexpression/knockdown proliferation assays in sheep/mouse cells","pmids":["38872805"],"confidence":"Medium","gaps":["Reciprocal validation of the S100A4-GNAI2 interaction limited","Mechanism of MAPK activation by the complex undefined"]},{"year":2024,"claim":"Reported that Gαi2 promotes dermal papilla cell proliferation via Wnt/β-Catenin signaling and is repressed by miR-181a.","evidence":"Dual luciferase assays and proliferation/induction assays in ovine dermal papilla cells","pmids":["39063192"],"confidence":"Low","gaps":["Wnt activation inferred without direct mechanistic dissection","Non-canonical ovine model, single lab"]},{"year":2025,"claim":"Placed Gαi2 downstream of GPR75 in a cAMP-PKA pathway controlling SREBP-1c maturation and hepatic lipogenesis.","evidence":"Hepatocyte-specific Gpr75 knockout/overexpression in a diet-induced MASH model with signaling analysis","pmids":["41632920"],"confidence":"Medium","gaps":["Direct GPR75-Gαi2 coupling not biochemically demonstrated","Single-lab, abstract-level detail"]},{"year":2025,"claim":"Reported a PRDX1-GNAI2 complex whose disruption by TMEM100 dampens LPS-induced NF-κB activation in endothelial cells.","evidence":"Co-immunoprecipitation and TMEM100 overexpression in an LPS acute lung injury model (preprint)","pmids":["bio_10.1101_2025.10.24.684325"],"confidence":"Low","gaps":["Single Co-IP without reciprocal validation","Preprint, abstract-level detail only"]},{"year":null,"claim":"How Gαi2 selectively engages distinct effector cascades (cAMP/PKA, PI3K, MAPK, NF-κB/STAT3) depending on receptor and tissue context remains undefined.","evidence":"","pmids":[],"confidence":"Low","gaps":["No unifying model for context-dependent effector selection","Direct receptor-to-Gαi2 coupling biochemically established for few of the described pathways"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0003924","term_label":"GTPase activity","supporting_discovery_ids":[1,3]},{"term_id":"GO:0060089","term_label":"molecular transducer activity","supporting_discovery_ids":[0,2]}],"localization":[{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[2]}],"pathway":[{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[0,2,9]},{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[0,2,5,8]},{"term_id":"R-HSA-1430728","term_label":"Metabolism","supporting_discovery_ids":[3,9]}],"complexes":["heterotrimeric G protein (Gi)","PRDX1-GNAI2 complex"],"partners":["RGS PROTEINS","GPR75","S100A4","PRDX1","TMEM100"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"P04899","full_name":"Guanine nucleotide-binding protein G(i) subunit alpha-2","aliases":["Adenylate cyclase-inhibiting G alpha protein"],"length_aa":355,"mass_kda":40.5,"function":"Guanine nucleotide-binding proteins (G proteins) function as transducers downstream of G protein-coupled receptors (GPCRs) in numerous signaling cascades (PubMed:38505600, PubMed:29925945, PubMed:35637350, PubMed:35365641). The alpha chain contains the guanine nucleotide binding site and alternates between an active, GTP-bound state and an inactive, GDP-bound state (PubMed:12359238). Signaling by an activated GPCR promotes GDP release and GTP binding (PubMed:29925945). Examples of interacting GPCRs include the adenosine A1 receptor/ADORA1, CNR1, and FPR2 (PubMed:29925945, PubMed:35637350, PubMed:35365641). The alpha subunit has a low GTPase activity that converts bound GTP to GDP, thereby terminating the signal. Both GDP release and GTP hydrolysis are modulated by numerous regulatory proteins (PubMed:12359238). Signaling is mediated via effector proteins, such as adenylate cyclase: inhibits adenylate cyclase activity of ADCY1, ADCY5 and ADCY6, leading to decreased intracellular cAMP levels. Plays an important role in the activation of the transcription factor NFAT in endothelial cells to promote angiogenesis (PubMed:38505600). The G(i) proteins are involved in hormonal regulation of adenylate cyclase: they inhibit the cyclase in response to beta-adrenergic stimuli. Plays an essential role for neutrophil recruitment in the context of acute inflammation suggesting a linked function of both GNAI2 in neutrophils and endothelial cells for polymorphonuclear neutrophils transmigration (By similarity) Regulates the cell surface density of dopamine receptors DRD2 by sequestrating them as an intracellular pool","subcellular_location":"Cytoplasm; Cytoplasm, cytoskeleton, microtubule organizing center, centrosome; Cell membrane; Membrane","url":"https://www.uniprot.org/uniprotkb/P04899/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/GNAI2","classification":"Not Classified","n_dependent_lines":27,"n_total_lines":1208,"dependency_fraction":0.022350993377483443},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/GNAI2","total_profiled":1310},"omim":[{"mim_id":"619344","title":"PURKINJE CELL PROTEIN 2; PCP2","url":"https://www.omim.org/entry/619344"},{"mim_id":"617686","title":"PITUITARY ADENOMA 3, MULTIPLE TYPES; PITA3","url":"https://www.omim.org/entry/617686"},{"mim_id":"613394","title":"MICRO RNA 138-1; MIR138-1","url":"https://www.omim.org/entry/613394"},{"mim_id":"612241","title":"INFLAMMATORY BOWEL DISEASE 12; IBD12","url":"https://www.omim.org/entry/612241"},{"mim_id":"609491","title":"G PROTEIN SIGNALING MODULATOR 1; GPSM1","url":"https://www.omim.org/entry/609491"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Cytosol","reliability":"Supported"},{"location":"Nucleoplasm","reliability":"Additional"},{"location":"Plasma membrane","reliability":"Additional"},{"location":"Basal body","reliability":"Additional"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/GNAI2"},"hgnc":{"alias_symbol":["GIP"],"prev_symbol":["GNAI2B"]},"alphafold":{"accession":"P04899","domains":[{"cath_id":"3.40.50.300","chopping":"39-60_182-340","consensus_level":"medium","plddt":95.9377,"start":39,"end":340},{"cath_id":"1.10.400.10","chopping":"62-175","consensus_level":"medium","plddt":97.3131,"start":62,"end":175}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/P04899","model_url":"https://alphafold.ebi.ac.uk/files/AF-P04899-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-P04899-F1-predicted_aligned_error_v6.png","plddt_mean":94.06},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=GNAI2","jax_strain_url":"https://www.jax.org/strain/search?query=GNAI2"},"sequence":{"accession":"P04899","fasta_url":"https://rest.uniprot.org/uniprotkb/P04899.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/P04899/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/P04899"}},"corpus_meta":[{"pmid":"15780991","id":"PMC_15780991","title":"Rgs1 and Gnai2 regulate the entrance of B lymphocytes into lymph nodes and B cell motility within lymph node follicles.","date":"2005","source":"Immunity","url":"https://pubmed.ncbi.nlm.nih.gov/15780991","citation_count":144,"is_preprint":false},{"pmid":"21079996","id":"PMC_21079996","title":"Identification and experimental validation of G protein alpha inhibiting activity polypeptide 2 (GNAI2) as a microRNA-138 target in tongue squamous cell carcinoma.","date":"2010","source":"Human genetics","url":"https://pubmed.ncbi.nlm.nih.gov/21079996","citation_count":85,"is_preprint":false},{"pmid":"30836096","id":"PMC_30836096","title":"GNAI1 and GNAI3 Reduce Colitis-Associated Tumorigenesis in Mice by Blocking IL6 Signaling and Down-regulating Expression of GNAI2.","date":"2019","source":"Gastroenterology","url":"https://pubmed.ncbi.nlm.nih.gov/30836096","citation_count":80,"is_preprint":false},{"pmid":"16943428","id":"PMC_16943428","title":"Pleiotropic phenotype of a genomic knock-in of an RGS-insensitive G184S Gnai2 allele.","date":"2006","source":"Molecular and cellular biology","url":"https://pubmed.ncbi.nlm.nih.gov/16943428","citation_count":67,"is_preprint":false},{"pmid":"17579064","id":"PMC_17579064","title":"Impaired trafficking of Gnai2+/- and Gnai2-/- T lymphocytes: implications for T cell movement within lymph nodes.","date":"2007","source":"Journal of immunology (Baltimore, Md. : 1950)","url":"https://pubmed.ncbi.nlm.nih.gov/17579064","citation_count":44,"is_preprint":false},{"pmid":"17928396","id":"PMC_17928396","title":"Resistance to diet-induced obesity and improved insulin sensitivity in mice with a regulator of G protein signaling-insensitive G184S Gnai2 allele.","date":"2007","source":"Diabetes","url":"https://pubmed.ncbi.nlm.nih.gov/17928396","citation_count":42,"is_preprint":false},{"pmid":"23977324","id":"PMC_23977324","title":"The loss of Gnai2 and Gnai3 in B cells eliminates B lymphocyte compartments and leads to a hyper-IgM like syndrome.","date":"2013","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/23977324","citation_count":26,"is_preprint":false},{"pmid":"24423449","id":"PMC_24423449","title":"Suppression of GNAI2 message in ovarian cancer.","date":"2014","source":"Journal of ovarian research","url":"https://pubmed.ncbi.nlm.nih.gov/24423449","citation_count":20,"is_preprint":false},{"pmid":"1733849","id":"PMC_1733849","title":"Regional localization of the human G protein alpha i2 (GNAI2) gene: assignment to 3p21 and a related sequence (GNAI2L) to 12p12-p13.","date":"1992","source":"Genomics","url":"https://pubmed.ncbi.nlm.nih.gov/1733849","citation_count":20,"is_preprint":false},{"pmid":"20508603","id":"PMC_20508603","title":"Variations in Gnai2 and Rgs1 expression affect chemokine receptor signaling and the organization of secondary lymphoid organs.","date":"2010","source":"Genes and 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PCBP1.","date":"2020","source":"Frontiers in pharmacology","url":"https://pubmed.ncbi.nlm.nih.gov/32536864","citation_count":13,"is_preprint":false},{"pmid":"34440304","id":"PMC_34440304","title":"GNAI2 Promotes Proliferation and Decreases Apoptosis in Rabbit Melanocytes.","date":"2021","source":"Genes","url":"https://pubmed.ncbi.nlm.nih.gov/34440304","citation_count":12,"is_preprint":false},{"pmid":"34747678","id":"PMC_34747678","title":"MiR-19 3b regulated the formation of coat colors by targeting WNT10A and GNAI2 in Cashmere goats.","date":"2021","source":"Animal biotechnology","url":"https://pubmed.ncbi.nlm.nih.gov/34747678","citation_count":10,"is_preprint":false},{"pmid":"10833069","id":"PMC_10833069","title":"Absence of GNAI2 codon 179 oncogene mutations in inflammatory bowel disease.","date":"2000","source":"Inflammatory bowel 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Gnai2-/- B cells enter lymph nodes poorly and move more slowly than wild-type B cells, and respond poorly to chemokines, demonstrating that Gαi1 and Gαi3 cannot compensate for loss of Gαi2 in this context.\",\n      \"method\": \"Intravital microscopy of adoptively transferred B cells from Gnai2-/- mice; chemokine response assays; genetic knockout with defined cellular phenotype\",\n      \"journal\": \"Immunity\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — direct intravital imaging with adoptive transfer, Gnai2-/- genetic model, defined chemotaxis defect, replicated by multiple subsequent studies\",\n      \"pmids\": [\"15780991\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"RGS proteins negatively regulate Gαi2 signaling in vivo. A G184S knock-in mutation in Gnai2 that blocks RGS protein binding produces a pleiotropic phenotype (enlarged spleen, elevated neutrophils, cardiac hypertrophy, shortened long bones, behavioral hyperactivity, reduced viability), demonstrating the essential role of RGS-mediated GTPase acceleration at Gαi2 across multiple organ systems.\",\n      \"method\": \"Genomic knock-in of RGS-insensitive G184S Gnai2 allele; phenotypic characterization of homozygous and heterozygous mice\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genomic knock-in with precise mutation blocking RGS binding, multi-organ phenotype in two zygosity states, replicated in follow-up metabolic study\",\n      \"pmids\": [\"16943428\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"GNAI2 (Gαi2) is essential for T lymphocyte chemokine receptor signaling. Gnai2-/- CD4 and CD8 T cells show profound defects in chemokine-induced intracellular calcium mobilization, chemotaxis, and lymph node homing. Intravital imaging showed Gnai2-/- CD4 T cells accumulate at the cortical ridge and fail to access the paracortex, lacking amoeboid movements and active membrane projections.\",\n      \"method\": \"Intravital imaging of Gnai2-/- T cells; chemotaxis assays; calcium mobilization assays; adoptive transfer homing assays\",\n      \"journal\": \"Journal of immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (imaging, calcium flux, chemotaxis, in vivo homing) in genetic knockout model\",\n      \"pmids\": [\"17579064\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"RGS proteins and Gαi2 signaling regulate insulin sensitivity, glucose metabolism, and body weight. Homozygous Gαi2(G184S) knock-in mice are resistant to diet-induced obesity on a high-fat diet and are protected from insulin resistance, associated with increased energy expenditure. Both male and female G184S mice show enhanced insulin sensitivity and glucose tolerance.\",\n      \"method\": \"RGS-insensitive G184S Gnai2 knock-in mice on high-fat diet; body composition analysis; glucose/insulin tolerance tests; energy expenditure measurement\",\n      \"journal\": \"Diabetes\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genomic knock-in model, multiple metabolic phenotype readouts, builds on same validated allele from prior Huang et al. study\",\n      \"pmids\": [\"17928396\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"The level of Gnai2 expression is a critical determinant of chemokine receptor signaling output and secondary lymphoid organ organization. Loss of a single Gnai2 allele reduces CCL19-triggered chemotaxis. Gnai2 is required for proper marginal zone B cell development, splenic architecture, lymphoid follicle size, germinal center morphology, and alignment of MOMA-1+ macrophages and MAdCAM-1+ endothelial cells along marginal zone sinuses.\",\n      \"method\": \"Mice with varying numbers of intact alleles of Ccr7, Rgs1, Gnai2, and Gnai3; chemotaxis assays; histological analysis of splenic architecture\",\n      \"journal\": \"Genes and immunity\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic dosage series with multiple readouts, single lab\",\n      \"pmids\": [\"20508603\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Combined loss of Gαi2 and Gαi3 in B cells eliminates B cell compartments at mucosal sites, splenic marginal zones, and lymph nodes, causes partial block in splenic follicular B cell development, disrupts lymphoid organ architecture, and produces a hyper-IgM-like syndrome. B cells lacking both subunits are refractory to chemokine stimulation and poorly responsive to antigen receptor engagement.\",\n      \"method\": \"B cell-specific conditional double knockout of Gnai2 and Gnai3; flow cytometry; histology; chemokine stimulation assays; immunoglobulin analysis\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — conditional double knockout with multiple orthogonal readouts (chemotaxis, histology, flow cytometry, immunoglobulin levels)\",\n      \"pmids\": [\"23977324\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"A -318 C>G SNP in the GNAI2 promoter impairs transcriptional activity by altering transcription factor binding specificity: the G allele binds Sp1 (confirmed by supershift with anti-Sp1 antibody), while the C allele binds YY1. The G allele has 2.5-fold reduced transcriptional activity in transfected HEK293 cells and is associated with higher systolic blood pressure.\",\n      \"method\": \"Electrophoretic mobility shift assay (EMSA) with competition; supershift with anti-Sp1 and anti-YY1 antibodies; luciferase reporter transfection in HEK293 cells\",\n      \"journal\": \"Journal of the American Society of Nephrology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — EMSA with supershift and reporter assay provide mechanistic evidence for transcription factor binding, single lab\",\n      \"pmids\": [\"16565233\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"GNAI2 is a direct target of miR-138 in tongue squamous cell carcinoma cells. miR-138 directly binds two candidate sequences in the 3'-UTR of GNAI2 mRNA (confirmed by luciferase reporter assay). Knockdown of miR-138 increases GNAI2 at mRNA and protein levels; ectopic miR-138 reduces GNAI2 expression and leads to reduced proliferation, cell cycle arrest, and apoptosis.\",\n      \"method\": \"Luciferase reporter assay; qPCR; Western blot; genome-wide expression profiling; miR-138 transfection/knockdown in TSCC cells\",\n      \"journal\": \"Human genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — luciferase reporter validation of direct 3'-UTR targeting plus phenotypic readouts, single lab\",\n      \"pmids\": [\"21079996\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"GNAI2 in CD11c+ dendritic cells promotes colitis-associated tumorigenesis. GNAI1 and GNAI3 suppress colonic tumor development by blocking IL6 signaling; their absence leads to increased GNAI2 expression. IL6 activates GNAI2 expression via JAK2-mediated NF-κB (through TRAF6-TAK1-CHUK/IKKβ) and STAT3 signaling pathways. Conditional disruption of Gnai2 in CD11c+ cells of GNAI1/3 double-knockout mice prevented NF-κB and STAT3 activation and normalized DC and MDSC numbers.\",\n      \"method\": \"Conditional knockout mice; immunoprecipitation; immunoblot; flow cytometry; IL6 antibody blockade; conditional Gnai2 disruption in CD11c+ cells; cytokine ELISA\",\n      \"journal\": \"Gastroenterology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple genetic models (single KO, double KO, conditional KO), reciprocal immunoprecipitation, functional rescue experiments, multiple orthogonal methods\",\n      \"pmids\": [\"30836096\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"GPR75 signals through GNAI2 to regulate hepatic lipid metabolism. Depletion of hepatic Gpr75 activates the GNAI2-cAMP-PKA signaling pathway, reducing SREBP-1c maturation and de novo lipogenesis. GPR75 overexpression in hepatocytes exacerbates diet-induced MASH and liver fibrosis, while its deficiency is protective.\",\n      \"method\": \"Hepatocyte-specific Gpr75 knockout and overexpression in mice; diet-induced MASH model; signaling pathway analysis (cAMP-PKA, SREBP-1c)\",\n      \"journal\": \"Hepatology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vivo genetic models with defined signaling pathway, single lab, abstract-level detail\",\n      \"pmids\": [\"41632920\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"miR-34b-5p negatively targets Gnai2 by directly binding its 3'-UTR (validated by dual luciferase reporter assay). In fluorine-aluminum-induced neuronal apoptosis, decreased Gnai2 expression (caused by increased miR-34b-5p) suppresses the PKA/ERK/CREB signaling pathway, and inhibition of miR-34b-5p alleviates apoptosis by restoring Gnai2, PKA, ERK, and CREB expression.\",\n      \"method\": \"Dual luciferase reporter assay; miR-34b-5p agomir/antagomir transfection; Western blot; rat hippocampal neuron model and NG108-15 cell model\",\n      \"journal\": \"Environmental science and pollution research international\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct 3'-UTR targeting validated by luciferase assay, pathway placement via multiple signaling readouts, single lab\",\n      \"pmids\": [\"37186186\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"S100A4 interacts with GNAI2 as a downstream binding partner (identified by co-immunoprecipitation and mass spectrometry), and S100A4 activates the MAPK signaling pathway to promote endometrial epithelial cell proliferation by targeting GNAI2. GnRH suppresses S100A4 expression, thereby inhibiting cell proliferation through the S100A4/GNAI2/MAPK pathway.\",\n      \"method\": \"Co-immunoprecipitation and mass spectrometry to identify GNAI2 as S100A4-interacting protein; overexpression/knockdown experiments; CCK-8 and EdU proliferation assays\",\n      \"journal\": \"Frontiers in veterinary science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 / Moderate — Co-IP/MS identification of interaction plus functional overexpression/knockdown assays, single lab, sheep/mouse model\",\n      \"pmids\": [\"38872805\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"TMEM100 interacts with both PRDX1 and GNAI2, disrupting the PRDX1-GNAI2 protein complex. This disruption inhibits LPS-induced NF-κB activation in pulmonary vascular endothelial cells, contributing to anti-inflammatory effects in acute lung injury.\",\n      \"method\": \"Co-immunoprecipitation; overexpression of TMEM100; LPS-induced acute lung injury model; NF-κB activation assays\",\n      \"journal\": \"bioRxiv\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — preprint, single Co-IP identifying complex disruption, single lab, abstract-level detail only\",\n      \"pmids\": [\"bio_10.1101_2025.10.24.684325\"],\n      \"is_preprint\": true\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"GNAI2 is a direct target of miR-181a in ovine dermal papilla cells (confirmed by dual luciferase reporter assay). GNAI2 promotes proliferation and induction ability of dermal papilla cells and activates the Wnt/β-Catenin signaling pathway. miR-181a inhibits dermal papilla cell proliferation and induction ability by targeting GNAI2.\",\n      \"method\": \"Dual luciferase reporter assay; qRT-PCR; Western blot; CCK-8; EdU assay; flow cytometry; alkaline phosphatase staining\",\n      \"journal\": \"International journal of molecular sciences\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — ovine model (non-mammalian canonical context), single lab, luciferase validation present but Wnt pathway activation inferred without direct mechanistic dissection\",\n      \"pmids\": [\"39063192\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"GNAI2 encodes the Gαi2 subunit of heterotrimeric G proteins, which transduces chemoattractant receptor signals to drive lymphocyte trafficking, chemotaxis, and compartmentalization in secondary lymphoid organs; its GTPase activity is accelerated by RGS proteins (blocked by the G184S mutation), and it signals through downstream pathways including cAMP inhibition, PI3K/Akt, PKA/ERK/CREB, MAPK, and NF-κB/STAT3 to regulate immune cell function, insulin sensitivity, lipid metabolism, and cell proliferation.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"GNAI2 encodes Gαi2, a heterotrimeric G protein α subunit that transduces chemoattractant-receptor signals to control lymphocyte trafficking and the architecture of secondary lymphoid organs [#0, #2]. Gαi2 is non-redundantly required for B and T cell chemokine responses: Gnai2-deficient lymphocytes home poorly to lymph nodes, show defective chemokine-induced calcium mobilization and chemotaxis, and lose the amoeboid motility needed to navigate lymphoid compartments, defects that Gαi1 and Gαi3 cannot compensate for [#0, #2]. Gαi2 dosage is itself a determinant of signaling output, controlling marginal zone B cell development and splenic architecture [#4], and combined loss of Gαi2 and Gαi3 in B cells eliminates mucosal, marginal zone, and lymph node B cell compartments and produces a hyper-IgM-like syndrome [#5]. Gαi2 signaling is negatively constrained by RGS proteins acting as GTPase-activating factors: an RGS-insensitive G184S knock-in allele yields a pleiotropic multi-organ phenotype and, metabolically, protects against diet-induced obesity and insulin resistance while increasing energy expenditure [#1, #3]. Downstream, Gαi2 couples receptors to discrete effector cascades — the cAMP-PKA axis controlling SREBP-1c maturation and hepatic lipogenesis downstream of GPR75 [#9], and NF-κB/STAT3 signaling driving colitis-associated tumorigenesis in dendritic cells [#8]. Gαi2 expression is regulated by promoter sequence variation affecting Sp1/YY1 binding [#6] and by direct 3'-UTR targeting by miR-138 [#7].\",\n  \"teleology\": [\n    {\n      \"year\": 2005,\n      \"claim\": \"Established that Gαi2 is non-redundantly required for B lymphocyte entry into and motility within lymph nodes, defining a specific physiological role for one Gαi isoform in immune cell trafficking.\",\n      \"evidence\": \"Intravital microscopy of adoptively transferred Gnai2-/- B cells with chemokine response assays\",\n      \"pmids\": [\"15780991\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not identify the specific chemokine receptors coupling to Gαi2\", \"Molecular basis of isoform non-redundancy not resolved\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Demonstrated that RGS-mediated GTPase acceleration is essential to constrain Gαi2 signaling in vivo, showing the consequences of unrestrained Gαi2 activity across multiple organ systems.\",\n      \"evidence\": \"Genomic knock-in of the RGS-insensitive G184S Gnai2 allele with phenotypic characterization in two zygosity states\",\n      \"pmids\": [\"16943428\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not assign individual RGS proteins to specific tissues\", \"Did not connect organ phenotypes to specific receptor-effector circuits\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Connected a GNAI2 promoter SNP to altered transcription factor binding and reduced expression, providing a mechanism for variation in Gαi2 levels linked to blood pressure.\",\n      \"evidence\": \"EMSA with Sp1/YY1 supershift and luciferase reporter assays in HEK293 cells\",\n      \"pmids\": [\"16565233\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Causal link between expression change and blood pressure not established in vivo\", \"Single-lab association\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Extended the chemotaxis requirement to T cells, showing Gαi2 is essential for chemokine-induced calcium flux, motility, and paracortical positioning.\",\n      \"evidence\": \"Intravital imaging, calcium mobilization, chemotaxis, and homing assays in Gnai2-/- T cells\",\n      \"pmids\": [\"17579064\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not map which downstream effectors mediate amoeboid movement\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Revealed a metabolic role for RGS-Gαi2 signaling, showing that blocking RGS regulation of Gαi2 protects against diet-induced obesity and insulin resistance.\",\n      \"evidence\": \"G184S knock-in mice on high-fat diet with glucose/insulin tolerance and energy expenditure measurements\",\n      \"pmids\": [\"17928396\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Tissue source of the metabolic phenotype not localized\", \"Receptor and effector pathway in metabolism not defined\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Showed that Gαi2 gene dosage quantitatively tunes chemokine signaling output and is required for proper splenic marginal zone organization.\",\n      \"evidence\": \"Allelic dosage series across Ccr7, Rgs1, Gnai2, and Gnai3 with chemotaxis and splenic histology\",\n      \"pmids\": [\"20508603\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single-lab study\", \"Mechanism linking dosage to architectural changes not dissected\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Identified post-transcriptional control of GNAI2 by miR-138 and linked its expression to proliferation and survival in carcinoma cells.\",\n      \"evidence\": \"Luciferase 3'-UTR reporter assays with miR-138 transfection/knockdown in tongue squamous cell carcinoma cells\",\n      \"pmids\": [\"21079996\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Downstream Gαi2 effector mediating proliferation not identified\", \"Single-lab study\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Demonstrated combinatorial requirement of Gαi2 and Gαi3 in B cells for compartment formation and immunoglobulin homeostasis.\",\n      \"evidence\": \"B cell-specific conditional double knockout with chemokine stimulation, histology, flow cytometry, and immunoglobulin analysis\",\n      \"pmids\": [\"23977324\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not separate Gαi2-specific from Gαi3-specific contributions in the double knockout\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Placed Gαi2 in an IL6-driven NF-κB/STAT3 circuit in dendritic cells, showing it promotes colitis-associated tumorigenesis when GNAI1/3 are lost.\",\n      \"evidence\": \"Conditional knockout and double-knockout mice, immunoprecipitation, IL6 blockade, and flow cytometry\",\n      \"pmids\": [\"30836096\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct biochemical coupling of Gαi2 to the JAK2/NF-κB/STAT3 machinery not fully resolved\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Linked Gαi2 to the PKA/ERK/CREB axis in neurons, where miR-34b-5p suppression of Gαi2 contributes to apoptosis.\",\n      \"evidence\": \"Dual luciferase 3'-UTR assays with miR-34b-5p agomir/antagomir and pathway Western blots in neuronal models\",\n      \"pmids\": [\"37186186\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Receptor upstream of Gαi2 in this context unknown\", \"Single-lab study\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Identified S100A4 as a physical partner that signals through Gαi2 to activate MAPK and drive endometrial epithelial proliferation.\",\n      \"evidence\": \"Co-IP/mass spectrometry plus overexpression/knockdown proliferation assays in sheep/mouse cells\",\n      \"pmids\": [\"38872805\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Reciprocal validation of the S100A4-GNAI2 interaction limited\", \"Mechanism of MAPK activation by the complex undefined\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Reported that Gαi2 promotes dermal papilla cell proliferation via Wnt/β-Catenin signaling and is repressed by miR-181a.\",\n      \"evidence\": \"Dual luciferase assays and proliferation/induction assays in ovine dermal papilla cells\",\n      \"pmids\": [\"39063192\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Wnt activation inferred without direct mechanistic dissection\", \"Non-canonical ovine model, single lab\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Placed Gαi2 downstream of GPR75 in a cAMP-PKA pathway controlling SREBP-1c maturation and hepatic lipogenesis.\",\n      \"evidence\": \"Hepatocyte-specific Gpr75 knockout/overexpression in a diet-induced MASH model with signaling analysis\",\n      \"pmids\": [\"41632920\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct GPR75-Gαi2 coupling not biochemically demonstrated\", \"Single-lab, abstract-level detail\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Reported a PRDX1-GNAI2 complex whose disruption by TMEM100 dampens LPS-induced NF-κB activation in endothelial cells.\",\n      \"evidence\": \"Co-immunoprecipitation and TMEM100 overexpression in an LPS acute lung injury model (preprint)\",\n      \"pmids\": [\"bio_10.1101_2025.10.24.684325\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Single Co-IP without reciprocal validation\", \"Preprint, abstract-level detail only\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How Gαi2 selectively engages distinct effector cascades (cAMP/PKA, PI3K, MAPK, NF-κB/STAT3) depending on receptor and tissue context remains undefined.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No unifying model for context-dependent effector selection\", \"Direct receptor-to-Gαi2 coupling biochemically established for few of the described pathways\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0003924\", \"supporting_discovery_ids\": [1, 3]},\n      {\"term_id\": \"GO:0060089\", \"supporting_discovery_ids\": [0, 2]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [2]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [0, 2, 9]},\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [0, 2, 5, 8]},\n      {\"term_id\": \"R-HSA-1430728\", \"supporting_discovery_ids\": [3, 9]}\n    ],\n    \"complexes\": [\"heterotrimeric G protein (Gi)\", \"PRDX1-GNAI2 complex\"],\n    \"partners\": [\"RGS proteins\", \"GPR75\", \"S100A4\", \"PRDX1\", \"TMEM100\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":6,"faith_total":6,"faith_pct":100.0}}