Affinage

LGALS9

Galectin-9 · UniProt O00182

Length
355 aa
Mass
39.5 kDa
Annotated
2026-06-10
29 papers in source corpus 14 papers cited in narrative 14 extracted findings
Cross-family judge vs UniProt: Affinage preferred faithfulness: 7/7 claims corpus-supported (100%)

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

LGALS9 (Galectin-9) is a secreted, cell-associated lectin that operates primarily as an immunomodulatory ligand shaping innate and adaptive immune responses across cancer, reproduction, and inflammatory disease (PMID:33093453, PMID:42103355). As a ligand for the TIM-3 receptor, tumor-derived LGALS9—including via exosomal delivery from glioblastoma cells—suppresses dendritic cell antigen presentation and cytotoxic T-cell priming, and disrupting this axis restores DC maturation and durable antitumor immunity (PMID:33093453, PMID:42103355). Beyond TIM-3, LGALS9 engages multiple partners to direct context-specific signaling: it binds peroxiredoxin-2 (PRDX2) in a carbohydrate-independent manner to control adipocyte redox state and diet-induced obesity (PMID:33727589), and rhamnose-promoted association with CEACAM1 raises DUSP1 levels to dampen p38-driven proinflammatory cytokine production in macrophages (PMID:40708539). It also acts cell-intrinsically: internalized recombinant LGALS9 accumulates in lysosomes and blocks autophagosome-lysosome fusion, selectively killing KRAS-mutant colorectal cancer cells with high basal autophagic flux (PMID:26086204). In tumor microenvironments, myeloid-derived LGALS9 reinforces epithelial proliferation through a CD47–HCK feedback loop in endometrial cancer (PMID:41437376), and its loss is protective in pristane-induced lupus by targeting activated macrophages (PMID:29481735). Genetic deletion phenotypes and isoform-specific functions in NK-cell cytokine suppression establish roles in reproduction and decidualization (PMID:23242525), where LGALS9 transcription is jointly controlled by HAND2 activation and FOXO1 repression (PMID:34581822). LGALS9 also exacerbates inflammation through JNK and ERK1/2 MAPK signaling in osteoarthritis (PMID:39278441).

Mechanistic history

Synthesis pass · year-by-year structured walk · 8 steps
  1. 2013 Medium

    Established that distinct LGALS9 splice isoforms carry separable functions in vascular and immune contexts, moving the gene beyond a single monolithic activity.

    Evidence Splice variant cloning, HMEC transfection, and recombinant protein assays for proliferation/migration/angiogenesis, plus isoform-specific NK-cell IFN-γ assays and a mouse abortion model

    PMID:23242525 PMID:24333696

    Open questions at the time
    • Receptors mediating isoform-specific effects not identified
    • Molecular basis for opposite proliferation/migration outcomes of the same isoform unresolved
  2. 2015 Medium

    Showed a cell-intrinsic, lysosome-based mechanism distinct from extracellular ligand signaling, defining LGALS9 as an inhibitor of autophagosome-lysosome fusion that is selectively lethal to KRAS-mutant cells.

    Evidence Endosomal/lysosomal live-cell imaging, autophagy flux and viability assays in KRAS- vs BRAF-mutant colorectal cancer lines

    PMID:26086204

    Open questions at the time
    • Molecular target within the lysosome not identified
    • Mechanism of KRAS-selectivity beyond elevated autophagic flux unclear
  3. 2018 Medium

    Defined the immune cell type through which LGALS9 drives autoimmune pathology, showing macrophages rather than lymphocyte subsets or the TLR7–IFN axis mediate disease.

    Evidence Lgals9 knockout in pristane-induced lupus mice with histopathology, immune subset flow cytometry, and pathway exclusion

    PMID:29481735

    Open questions at the time
    • Macrophage receptor for LGALS9 in this setting not identified
    • Downstream signaling in activated macrophages not mapped
  4. 2020 Medium

    Identified exosomal delivery of LGALS9 as a route for tumor immune evasion via the TIM-3 axis on dendritic cells, and showed transcription is governed primarily by histone acetylation rather than DNA methylation.

    Evidence CSF exosome proteomics, TIM-3/LGALS9 binding assays, and in vivo secretion blockade; separately ChIP for H3K9ac/H3K14ac and bisulfite sequencing in cervical cancer cells

    PMID:32902187 PMID:33093453

    Open questions at the time
    • Mechanism of LGALS9 packaging into exosomes unknown
    • Histone acetylation finding is correlative without functional perturbation (Low confidence)
  5. 2021 Medium

    Revealed carbohydrate-independent partnerships and transcriptional control, identifying PRDX2 binding that links LGALS9 to redox/metabolic regulation and a HAND2/FOXO1 logic gate governing its expression during decidualization.

    Evidence nanoLC-MS/MS, Co-IP and pull-down with PRDX2 redox western blots, Lgals9 KO mice with bone marrow transplant; promoter-reporter and siRNA knockdown of HAND2/FOXO1 with phospho-FOXO1 DNA-binding assays

    PMID:33727589 PMID:34581822

    Open questions at the time
    • How PRDX2 binding alters its oxidation state mechanistically unresolved
    • Direct vs indirect transcriptional control by HAND2 not fully separated
  6. 2025 Medium

    Expanded the partner repertoire and tumor-microenvironment roles, identifying CEACAM1 and P4HB as interactors and a CD47–HCK–LGALS9 macrophage-epithelial feedback loop.

    Evidence Co-IP (CEACAM1) with DUSP1/p-p38 readouts and LPS endotoxic model; GST pull-down MS and CUT&Tag with organoid-macrophage co-culture (CD47–HCK); scRNA-seq ligand-receptor inference plus P4HB inhibition for gastric cancer

    PMID:40534096 PMID:40708539 PMID:41437376

    Open questions at the time
    • Direct LGALS9–P4HB binding not confirmed biochemically (Low confidence)
    • Whether CEACAM1 and CD47 effects share a common signaling node unknown
  7. 2025 Medium

    Linked LGALS9 to macrophage polarization and MAPK-driven inflammation, broadening its functional output to M2b polarization and JNK/ERK1/2 activation.

    Evidence Recombinant Lgals9 macrophage polarization assays with scRNA-seq (heart transplant); RNAi and lentiviral gain/loss-of-function with MAPK western blots in osteoarthritis models

    PMID:39278441 PMID:39835675

    Open questions at the time
    • M2b polarization mechanism lacks mechanistic depth (Low confidence)
    • Receptor coupling LGALS9 to JNK/ERK1/2 not defined
  8. 2026 Medium

    Validated therapeutic disruption of the LGALS9/TIM-3 axis, showing blockade reverses T-cell exhaustion and enhances DC maturation and CD8+ T-cell priming.

    Evidence Adenoviral immunization, neutralizing antibodies, ELISpot, CTL assays, and cell-depletion experiments in prostate cancer mouse models

    PMID:42103355

    Open questions at the time
    • Relative contribution of TIM-3 vs other LGALS9 partners to exhaustion not isolated
    • Durability and resistance mechanisms not assessed

Open questions

Synthesis pass · forward-looking unresolved questions
  • A unifying biochemical account of how a single lectin selects among TIM-3, PRDX2, CEACAM1, CD47-axis, and P4HB partners—and toggles between extracellular ligand signaling and intracellular lysosomal inhibition—remains undefined.
  • No structural basis for partner selectivity
  • Determinants of secretion vs internalization vs exosomal packaging unknown
  • Carbohydrate-dependent vs independent binding modes not systematically compared

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0048018 receptor ligand activity 3 GO:0098772 molecular function regulator activity 3
Localization
GO:0005576 extracellular region 2 GO:0005764 lysosome 1 GO:0005768 endosome 1
Pathway
R-HSA-168256 Immune System 3 R-HSA-162582 Signal Transduction 2 R-HSA-9612973 Autophagy 1

Evidence

Reading pass · 14 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2020 Exosomal LGALS9 derived from glioblastoma cells binds to the TIM-3 receptor on dendritic cells in the cerebrospinal fluid, inhibiting antigen recognition, processing, and presentation by DCs, thereby preventing cytotoxic T-cell-mediated antitumor immune responses. Blocking exosomal LGALS9 secretion restored DC antigen-presenting activity and induced durable antitumor immunity in mice. Proteomics of CSF exosomes, receptor-ligand binding assay (TIM-3/LGALS9), in vivo mouse model with LGALS9 secretion blockade, functional DC and T-cell assays Cell death & disease Medium 33093453
2015 Recombinant LGALS9 (rLGALS9) internalizes via early and late endosomes and accumulates in the lysosomal compartment of KRAS-mutant colorectal cancer cells, where it acts as a lysosomal inhibitor blocking autophagosome-lysosome fusion. This leads to autophagosome accumulation, excessive lysosomal swelling, and cell death selectively in KRAS-mutant (but not BRAF-mutant) CRC cells with elevated basal autophagic flux. Live cell imaging (endosomal/lysosomal tracking), autophagy flux assays, cell viability assays, genetic mutant cell lines (KRAS vs BRAF) Autophagy Medium 26086204
2013 Endothelial cells express five LGALS9 splice variants (including two novel ones) confined to exons 5, 6, and 10. Transfection of HMEC with the galectin-9Δ5 splice variant increased proliferation; exogenous recombinant galectin-9Δ5 protein dose-dependently reduced endothelial cell proliferation and migration in vitro and induced a small inhibitory effect on angiogenesis in vivo, while also enhancing sprouting toward a galectin-9Δ5 gradient. Transfection/overexpression in HMEC, recombinant protein treatment, in vitro proliferation and migration assays, in vivo angiogenesis assay Biochimica et biophysica acta Medium 24333696
2013 The LGALS9 D5 isoform suppresses interferon-gamma production by decidual natural killer cells. Decidual LGALS9 expression is deregulated in a mouse model of spontaneous abortion, and decreased LGALS9 D5/10 isoform expression is associated with spontaneous abortion in humans. Real-time PCR, immunohistochemistry, functional NK cell cytokine assay (IFN-γ production), mouse model of spontaneous abortion Biology of reproduction Medium 23242525
2021 Galectin-9 (Gal-9/LGALS9) binds to peroxiredoxin-2 (PRDX2) in a sugar chain-independent manner. In 3T3-L1 adipocytes, Gal-9 knockdown shifts PRDX2 from its oxidized dimer form to the reduced monomer form under oxidative stress. Lgals9-deficient mice are resistant to diet-induced obesity with reduced adipose tissue and improved glucose tolerance, and bone marrow transplant experiments indicate the effect is non-hematopoietic-cell-autonomous. nanoLC-MS/MS, co-immunoprecipitation, pull-down assay, Gal-9 knockdown in adipocytes, western blot (PRDX2 redox state), Lgals9 knockout mouse with bone marrow transplantation Scientific reports Medium 33727589
2018 Lgals9 deficiency in BALB/c mice protected against pristane-induced lupus nephritis, arthritis, and lipogranuloma formation without altering T-cell or B-cell subset composition in spleen or peritoneum, and without affecting the TLR7–type I interferon pathway. The protective effect was mediated through targeting of activated macrophages. Lgals9 knockout mouse model (pristane-induced lupus), histopathology, flow cytometry of immune subsets, cytokine profiling from peritoneal macrophages Arthritis & rheumatology Medium 29481735
2021 LGALS9 transcription in endometrial stromal cells is upregulated by HAND2 and downregulated by FOXO1. Phosphorylated FOXO1 (pFOXO1) cannot bind DNA and thus cannot directly suppress LGALS9 transcription, so the phosphorylation status of FOXO1 and expression of HAND2 together determine LGALS9 mRNA levels during decidualization. Promoter-reporter transcriptional activity assays, siRNA knockdown of HAND2 and FOXO1, RT-qPCR, phospho-FOXO1 chromatin binding assay Molecular human reproduction Medium 34581822
2020 Histone H3K9 and H3K14 acetylation at the LGALS9 promoter correlates with LGALS9 mRNA levels in cervical cancer cells, while CpG methylation at the promoter does not show hypermethylation associated with low LGALS9 expression. This suggests histone acetylation, not DNA methylation, is the primary epigenetic regulator of LGALS9 transcription. Chromatin immunoprecipitation (ChIP) for H3K9ac and H3K14ac, bisulfite sequencing for CpG methylation, RT-qPCR FEBS open bio Low 32902187
2025 In early-stage endometrial cancer, CD47⁺ epithelial cells interact with macrophages through the CD47–HCK (Hemopoietic Cell Kinase) axis, driving macrophage secretion of LGALS9, IL-10, and TGF-β1. Macrophage-derived LGALS9 in turn reinforces EC cell proliferation via CD47, establishing a positive feedback loop (CD47–HCK–LGALS9). ERRγ was identified as an upstream transcriptional regulator of CD47, suppressible by progesterone. GST pull-down mass spectrometry, molecular docking, CUT&Tag (transcription factor identification), organoid–macrophage co-culture model, flow cytometry, CCK-8 proliferation assay Molecular cancer Medium 41437376
2025 Rhamnose binds to sites V39, D40, and T101 of CEACAM1, promoting the interaction between CEACAM1 and LGALS9, which increases DUSP1 protein levels, inhibits p38 phosphorylation, and thereby attenuates LPS-triggered proinflammatory cytokine expression in macrophages. In vitro macrophage binding assays, Co-immunoprecipitation (CEACAM1–LGALS9), western blot (DUSP1, p-p38), LPS-induced endotoxic mouse model, site-directed mutagenesis/docking for binding sites Acta biochimica et biophysica Sinica Medium 40708539
2025 Recombinant Lgals9 (rLgals9) treatment polarized macrophages toward the M2b phenotype at appropriate concentrations in vitro, as validated by flow cytometry and ELISA. Single-cell RNA sequencing showed significant downregulation of Lgals9 in macrophages after mouse heart transplantation. Recombinant protein treatment of macrophages, flow cytometry (M2b polarization markers), ELISA, scRNA-seq, RT-qPCR, western blot Journal of leukocyte biology Low 39835675
2025 In gastric cancer, myeloid cell-derived LGALS9 binds to P4HB (beta-subunit of prolyl 4-hydroxylase) on epithelial cells as a ligand-receptor pair. Activation of P4HB by LGALS9 enhanced proliferation, epithelial-mesenchymal transition (EMT), and lipid metabolism in gastric cancer cells; pharmacological inhibition of P4HB reversed these effects. Single-cell RNA sequencing (ligand-receptor inference), functional experiments with LGALS9 treatment and P4HB inhibition, proliferation assays, EMT marker analysis Journal of cellular and molecular medicine Low 40534096
2026 LGALS9 blockade (via adenoviral immunization) enhanced dendritic cell activation and maturation (upregulating CD80, CD86, MHC-II, CD40), promoted CD8+ T-cell priming and expansion, and disrupted the LGALS9/TIM-3 inhibitory axis via neutralizing antibodies, alleviating T-cell exhaustion in prostate cancer models. Adenoviral vector immunization, flow cytometry, ELISA, ELISpot, cytotoxic T lymphocyte assay, cell depletion experiments, in vivo mouse tumor models Journal for immunotherapy of cancer Medium 42103355
2024 In osteoarthritis, LGALS9 exacerbates inflammatory responses by activating JNK and ERK1/2 (MAPK) signaling pathways. RNAi-mediated knockdown and lentiviral overexpression/knockdown in in vitro and in vivo OA models confirmed this regulatory role. RNAi knockdown, lentiviral overexpression/knockdown, western blot, qRT-PCR, immunofluorescence, safranin fast green staining, in vivo OA model International journal of biological macromolecules Medium 39278441

Source papers

Stage 0 corpus · 29 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2022 A new emerging target in cancer immunotherapy: Galectin-9 (LGALS9). Genes & diseases 125 37554219
2020 Exosomal LGALS9 in the cerebrospinal fluid of glioblastoma patients suppressed dendritic cell antigen presentation and cytotoxic T-cell immunity. Cell death & disease 98 33093453
2019 Molecular and immune correlates of TIM-3 (HAVCR2) and galectin 9 (LGALS9) mRNA expression and DNA methylation in melanoma. Clinical epigenetics 59 31747929
2013 Endothelial LGALS9 splice variant expression in endothelial cell biology and angiogenesis. Biochimica et biophysica acta 55 24333696
2015 The epithelial polarity regulator LGALS9/galectin-9 induces fatal frustrated autophagy in KRAS mutant colon carcinoma that depends on elevated basal autophagic flux. Autophagy 42 26086204
2013 Profiling Lgals9 splice variant expression at the fetal-maternal interface: implications in normal and pathological human pregnancy. Biology of reproduction 37 23242525
2018 Role of Lgals9 Deficiency in Attenuating Nephritis and Arthritis in BALB/c Mice in a Pristane-Induced Lupus Model. Arthritis & rheumatology (Hoboken, N.J.) 26 29481735
2020 Histone H3K9 and H3K14 acetylation at the promoter of the LGALS9 gene is associated with mRNA levels in cervical cancer cells. FEBS open bio 20 32902187
2019 Galectin-9 gene (LGALS9) polymorphisms are associated with rheumatoid arthritis in Brazilian patients. PloS one 12 31600237
2021 Gene polymorphisms of LGALS2, LGALS3 and LGALS9 in patients with rheumatoid arthritis. Cellular immunology 9 34371260
2024 Summary data-based Mendelian randomization and single-cell RNA sequencing analyses identify immune associations with low-level LGALS9 in sepsis. Journal of cellular and molecular medicine 8 39044269
2021 Transcriptional regulation of LGALS9 by HAND2 and FOXO1 in human endometrial stromal cells in women with regular cycles. Molecular human reproduction 8 34581822
2015 Variants in the LGALS9 Gene Are Associated With Development of Liver Disease in Heavy Consumers of Alcohol. Clinical gastroenterology and hepatology : the official clinical practice journal of the American Gastroenterological Association 8 26598225
2025 Targeting the CD47-HCK-LGALS9 axis disrupts proliferation-immunosuppression coupling in early-stage endometrial cancer. Molecular cancer 4 41437376
2024 Potential Plasma Proteins (LGALS9, LAMP3, PRSS8 and AGRN) as Predictors of Hospitalisation Risk in COVID-19 Patients. Biomolecules 4 39334929
2021 Lgals9 deficiency ameliorates obesity by modulating redox state of PRDX2. Scientific reports 4 33727589
2025 Myeloid-Derived LGALS9-P4HB Immune Interaction Promotes Metastasis in Gastric Cancer Through Enhanced Cell Proliferation and Lipid Metabolism. Journal of cellular and molecular medicine 2 40534096
2024 Circulating CD8 + LGALS9 + T Cell Population Exhibiting Low Cytotoxic Characteristics are Decreased in Patients with Systemic Lupus Erythematosus. Immunologic research 2 39046608
2024 Study on pro-inflammatory effect and mechanism of galectin-9 (LGALS9) in osteoarthritis: Exacerbating inflammatory response by activating JNK and ERK1/2 pathways. International journal of biological macromolecules 2 39278441
2023 Nicotine Potentially Alters Endothelial Inflammation and Cell Adhesion via LGALS9. Journal of cardiovascular development and disease 2 38248876
2025 Single-cell RNA sequencing revealed the immunophenotypic features of macrophages in cardiac transplants and uncovered Lgals9 promoted their polarization toward the M2b subtype. Journal of leukocyte biology 1 39835675
2026 Dynamic changes in TREX1 and LGALS9 mRNA levels in PBMCs predict HBsAg clearance and treatment responses to Peg-IFN-α therapy in HBeAg-negative chronic hepatitis B patients. Virology journal 0 41866580
2026 LGALS9 blockade augments vaccine-induced immune responses against prostate cancer. Journal for immunotherapy of cancer 0 42103355
2026 TPM1 drives cytoskeleton-immunometabolism coupling and LGALS9/CD45-mediated neuroinflammatory propagation in retinitis pigmentosa. Science advances 0 42202020
2025 Autophagy inhibition in LGALS9-overexpressing nasopharyngeal carcinoma unleashes immune response. Autophagy 0 40698512
2025 Rhamnose alleviates the proinflammatory response during endotoxemia via the CEACAM1/LGALS9-p38 axis. Acta biochimica et biophysica Sinica 0 40708539
2025 Single-cell RNA sequencing reveals LGALS9+ epithelial and COMP+ stromal cell crosstalk driving keratoconus pathogenesis. International journal of biological macromolecules 0 41022233
2025 The LGALS9/miR-491-5p Axis Regulates CD8+ T Cell Function and Inhibits the Progression of Gastric Cancer. Cancer science 0 41171621
2025 MFSD12 promotes proliferation, metastasis and invasion of hepatocellular carcinoma cells and its potential correlation with HAVCR2/LGALS9 immune checkpoint axis. Frontiers in immunology 0 41194934

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