Affinage

IRX1

Iroquois-class homeodomain protein IRX-1 · UniProt P78414

Length
480 aa
Mass
49.6 kDa
Annotated
2026-06-10
31 papers in source corpus 16 papers cited in narrative 16 extracted findings
Cross-family judge faithfulness: 6/6 claims corpus-supported (100%)

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

IRX1 is a homeodomain transcription factor that controls cell-fate decisions in development and tumor progression by directly transactivating or repressing target genes, with its own expression governed by promoter DNA methylation (PMID:20440264, PMID:29802960). In cancer it behaves in a context-dependent manner: it acts as a tumor suppressor in gastric cancer, where promoter hypermethylation (rather than mutation) silences it and re-expression inhibits growth, invasion, and tumorigenesis through direct ChIP-confirmed targets BDKRB2, HIST2H2BE, and FGF7, with the IRX1→BDKRB2→PAK1 axis suppressing angiogenesis and vasculogenic mimicry (PMID:20440264, PMID:21602894); conversely it drives osteosarcoma metastasis by activating CXCL14/NF-κB signaling (PMID:25822025). In breast cancer IRX1 suppresses progression by binding NME1, promoting its nuclear localization, and transcriptionally downregulating ACACA to limit de novo fatty acid synthesis (PMID:42225620). Its silencing is enforced by upstream epigenetic regulators: PRMT5 recruits DNMT3A to the IRX1 promoter to increase methylation, while TET1-mediated demethylation (antagonized by miR-646) reactivates it (PMID:29802960, PMID:33667646). Developmentally, IRX1 is a downstream effector in multiple lineage programs—required for alveolar type II cell maturation and surfactant secretion and for dental epithelial differentiation via Foxj1 and Sox9 (PMID:28746823), for gingival stem-cell-driven oral wound healing through SOX9 and EGF signaling (PMID:39782692), and it acts downstream of HNF1B in nephron segmentation and in a reciprocal regulatory loop with Six1 during cranial placode formation (PMID:23362348, PMID:30529252). IRX1 also modulates hematopoietic transcription, activating KLF1 and TAL1 in megakaryocyte-erythroid progenitors and counteracting the MLL-AF4 complex at target promoters in leukemia (PMID:27175594, PMID:35328612).

Mechanistic history

Synthesis pass · year-by-year structured walk · 13 steps
  1. 2010 High

    Established IRX1 as an epigenetically silenced tumor suppressor with defined direct transcriptional targets, answering how loss of a homeodomain factor contributes to gastric cancer.

    Evidence 5-Aza-dC reactivation, IRX1 transfection, ChIP, and in vitro/in vivo tumorigenesis assays in gastric cancer

    PMID:20440264

    Open questions at the time
    • Whether IRX1 directly activates or represses BDKRB2/HIST2H2BE/FGF7 not resolved
    • No structural basis for promoter binding
  2. 2011 High

    Defined the downstream mechanism by which IRX1 suppresses metastasis, linking it through BDKRB2 to PAK1 to control angiogenesis and vasculogenic mimicry.

    Evidence IRX1 transfection, BDKRB2/PAK1 siRNA, HUVEC and VM assays, murine metastasis models

    PMID:21602894

    Open questions at the time
    • Direct vs indirect regulation of PAK1 not distinguished
    • Generalizability beyond gastric cancer untested at this stage
  3. 2013 Medium

    Placed IRX1 in a developmental transcription cascade downstream of HNF1B, establishing its role in nephron segment fate.

    Evidence Hnf1b conditional knockout, ChIP at IRX1/2 regulatory regions, Xenopus dominant-negative, in situ hybridization

    PMID:23362348

    Open questions at the time
    • IRX1's own downstream targets in nephron not identified
    • Functional requirement of IRX1 (vs IRX2) not separated
  4. 2015 High

    Revealed the opposite, oncogenic role of IRX1 in osteosarcoma, showing context-dependent function via CXCL14/NF-κB signaling.

    Evidence MeDIP-microarray, gain/loss-of-function in cell lines, in vitro invasion/anoikis assays, murine lung metastasis

    PMID:25822025

    Open questions at the time
    • Whether CXCL14 is a direct transcriptional target not shown
    • Basis of tissue-specific tumor-suppressor vs oncogene switch unexplained
  5. 2016 Medium

    Showed IRX1 can antagonize the MLL-AF4 oncogenic complex at chromatin and drive HOXB4/EGR transcription, extending its transcriptional repertoire to leukemia.

    Evidence ChIP at target promoters, gene expression and HDACi perturbation in t(4;11) leukemia cells

    PMID:27175594

    Open questions at the time
    • Direct physical interaction with MLL-AF4 components not biochemically defined
    • Single cell-line context
  6. 2017 Medium

    Demonstrated IRX1 is essential for lung and dental epithelial differentiation through Foxj1 and Sox9, establishing a non-redundant developmental requirement.

    Evidence Irx1 LacZ knock-in null mice, lineage tracing, lung/dental phenotyping, target gene analysis

    PMID:28746823

    Open questions at the time
    • Direct vs indirect regulation of Foxj1/Sox9 not established by ChIP
    • Single lab
  7. 2018 High

    Identified PRMT5–DNMT3A as the upstream machinery enforcing IRX1 promoter methylation, explaining how IRX1 silencing is established in gastric cancer.

    Evidence Reciprocal Co-IP, ChIP for DNMT3A at IRX1 promoter, PRMT5 perturbation, tumorigenicity assays

    PMID:29802960

    Open questions at the time
    • Whether PRMT5 methyltransferase activity is required mechanistically not isolated
    • Generality across other IRX1-silenced tissues untested
  8. 2018 Medium

    Extended IRX1's transcriptional activity to hematopoiesis by showing activation of KLF1 and TAL1 at the MEP stage.

    Evidence RNA-seq, IRX1 knockdown/stimulation in AML cell lines, comparative expression

    PMID:35328612

    Open questions at the time
    • Direct binding to KLF1/TAL1 promoters not confirmed by ChIP
    • Limited mechanistic depth
  9. 2018 Medium

    Defined a reciprocal regulatory loop between Irx1 and Six1 (and Sox11) governing cranial placode and otic vesicle patterning.

    Evidence Xenopus explants, microarray, gain/loss-of-function epistasis, in situ hybridization

    PMID:30529252

    Open questions at the time
    • Direct transcriptional vs indirect cross-regulation not resolved
    • Single model organism
  10. 2021 Medium

    Identified the miR-646–TET1 axis as a demethylation route controlling IRX1, linking IRX1 reactivation to HIST2H2BE repression in breast carcinoma.

    Evidence miR-646 gain/loss, methylation-specific PCR, ChIP for TET1 at IRX1 promoter, in vitro/in vivo assays

    PMID:33667646

    Open questions at the time
    • Causal chain from IRX1 to HIST2H2BE not shown to be direct here
    • Single lab
  11. 2022 Medium

    Showed IRX1 expression level functionally determines neural differentiation propensity of hiPSCs, tying its methylation status to stem-cell fate.

    Evidence Methylation EPIC array across 32 hiPSC lines, IRX1/2 forced expression, neural differentiation assay

    PMID:36514370

    Open questions at the time
    • Downstream neural targets of IRX1 not identified
    • IRX1 vs IRX2 contributions not separated
  12. 2025 Medium

    Defined a non-transcription-factor partner mechanism: IRX1 binds NME1, drives its nuclear localization, and the complex represses ACACA to suppress fatty acid synthesis in breast cancer.

    Evidence Co-IP, nuclear localization assays, IRX1 perturbation, fatty acid synthesis assays, tumor models

    PMID:42225620

    Open questions at the time
    • Structural basis of IRX1-NME1 interaction unknown
    • Whether ACACA repression is direct promoter binding not confirmed
  13. 2025 Medium

    Established IRX1 as required for oral epithelial wound healing through SOX9 and EGF signaling in stem-cell niches.

    Evidence Irx1+/- mice, RNA-seq, Krt14CreERT lineage tracing, wound healing assays, immunofluorescence

    PMID:39782692

    Open questions at the time
    • Direct transcriptional targets vs indirect effects not separated
    • Single lab

Open questions

Synthesis pass · forward-looking unresolved questions
  • The molecular basis for IRX1's context-dependent switch between tumor-suppressor and oncogenic transcriptional programs, and the rules determining its activator-versus-repressor activity on a given promoter, remain unresolved.
  • No structural model of IRX1 DNA binding or cofactor selection
  • Cofactor partners beyond NME1 and MLL-AF4 not mapped
  • No unified explanation for tissue-specific opposite roles

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0140110 transcription regulator activity 6 GO:0003677 DNA binding 2
Localization
GO:0005634 nucleus 1
Pathway
R-HSA-1266738 Developmental Biology 4 R-HSA-1643685 Disease 3 R-HSA-74160 Gene expression (Transcription) 3

Evidence

Reading pass · 16 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2015 IRX1 promotes osteosarcoma metastasis by upregulating CXCL14/NF-κB signaling; experimental modulation of IRX1 in osteosarcoma cell lines altered migration, invasion, and resistance to anoikis in vitro, and lung metastasis in murine models, with effects mediated through CXCL14/NF-κB pathway activation. MeDIP-microarray screening, IRX1 overexpression/knockdown in cell lines, in vitro migration/invasion/anoikis assays, murine lung metastasis models The Journal of clinical investigation High 25822025
2010 IRX1 functions as a tumor suppressor in gastric cancer; its expression is silenced by promoter hypermethylation (not mutation), and restoring IRX1 expression inhibits growth, invasion, and tumorigenesis. Direct IRX1 target genes identified by ChIP assay include BDKRB2, HIST2H2BE, and FGF7. 5-Aza-dC treatment, IRX1 transfection, global microarray, real-time PCR, chromatin immunoprecipitation (ChIP), in vitro and in vivo tumorigenesis assays Oncogene High 20440264
2011 IRX1 suppresses peritoneal spreading and pulmonary metastasis in gastric cancer via inhibition of angiogenesis and vasculogenic mimicry (VM), mechanistically through downregulation of its direct target BDKRB2 and its downstream effector PAK1; siRNA knockdown of BDKRB2 or PAK1 inhibited tube formation, proliferation, migration, and invasion. IRX1 transfection, siRNA knockdown of BDKRB2/PAK1, HUVEC angiogenesis assays, chick embryo assay, VM formation assay, in vivo murine metastasis models Oncogene High 21602894
2018 PRMT5 acts as an upstream epigenetic repressor of IRX1 in gastric cancer by recruiting DNMT3A to the IRX1 promoter, increasing promoter methylation and silencing IRX1 expression; Co-IP confirmed PRMT5-DNMT3A interaction and ChIP confirmed DNMT3A recruitment to the IRX1 promoter. Co-immunoprecipitation, chromatin immunoprecipitation (ChIP), PRMT5 overexpression/knockdown, methylation analysis, in vitro and in vivo tumorigenicity assays Biochimica et biophysica acta. Molecular basis of disease High 29802960
2017 Irx1 null mice are neonatal lethal due to pulmonary immaturity; Irx1 marks alveolar type II cells and is required for surfactant protein secretion. In dental development, Irx1 is expressed in outer enamel epithelium and mediates dental epithelial cell differentiation. Mechanistically, Irx1 regulates Foxj1 and Sox9 to control cell differentiation. Irx1 LacZ knock-in null mice, histology, LacZ lineage tracing, lung and dental phenotype analysis, target gene expression analysis (Foxj1, Sox9) Developmental biology Medium 28746823
2016 IRX1 binds to the MLL-AF4 complex at target gene promoters and counteracts its promoter-activating function in t(4;11) leukemia cells; IRX1 also induces transcription of HOXB4 and EGR family members. ChIP at target gene promoters, gene expression analysis, HDACi perturbation experiments in t(4;11) leukemia cell lines Oncotarget Medium 27175594
2021 miR-646 targets TET1, reducing TET1-mediated demethylation of the IRX1 promoter, which suppresses IRX1 expression; reduced IRX1 leads to upregulation of HIST2H2BE, promoting invasive ductal carcinoma progression. ChIP confirmed TET1 enrichment at the IRX1 promoter. miR-646 gain/loss-of-function, methylation-specific PCR, ChIP for TET1 at IRX1 promoter, RT-qPCR, Western blot, in vitro and in vivo functional assays Genomics Medium 33667646
2018 IRX1 activates KLF1 and TAL1 transcription in megakaryocyte-erythroid progenitors (MEPs); knockdown and stimulation experiments in AML cell lines confirmed these as IRX1 target genes, implicating IRX1 in normal myeloid differentiation at the MEP stage. RNA-seq expression profiling, IRX1 knockdown and stimulation experiments in AML cell lines (megakaryoblastic and myelomonocytic), comparative gene expression analysis International journal of molecular sciences Medium 35328612
2025 IRX1 is expressed in gingival epithelial basal stem cell niches and is required for oral wound healing; mechanistically, IRX1 activates SOX9 in the transient amplifying layer to increase cell proliferation and activates EGF signaling to induce cell migration. Irx1+/- heterozygous mice show delayed wound closure and defective keratinocyte proliferation/differentiation. Irx1+/- heterozygous mice, RNA-seq (WT vs Irx1+/-), Krt14CreERT lineage tracing, wound healing assays, immunofluorescence, gene expression analysis JCI insight Medium 39782692
2013 HNF1B controls IRX1/2 expression during nephron segmentation; HNF1B is recruited to regulatory sequences of IRX1/2 and their downregulation (alongside Notch pathway components) accompanies failure of proximal-intermediate nephron segment fate acquisition upon Hnf1b conditional inactivation. Hnf1b conditional knockout in murine nephron progenitors, ChIP (HNF1B binding to IRX1/2 regulatory regions), Xenopus dominant-negative overexpression, in situ hybridization Development (Cambridge, England) Medium 23362348
2018 Six1 and Irx1 reciprocally regulate each other during cranial placode and otic vesicle formation in Xenopus; Six1 expands then represses Irx1 expression, while Irx1 initially expands then represses Six1; Irx1 and Sox11 (a direct Six1 target) also reciprocally regulate each other. Xenopus ectodermal explants, microarray screen, gain- and loss-of-function experiments, in situ hybridization, temporal expression analysis Developmental biology Medium 30529252
2022 DNA methylation of the IRX1/2 locus in undifferentiated hiPSCs correlates with neural differentiation propensity; forced expression of IRX1/2 impaired neural differentiation ability of hiPSCs, demonstrating a functional role for IRX1 expression levels in determining neural stem cell fate. Infinium MethylationEPIC BeadChip (32 hiPSC lines), HSIC Lasso feature selection, IRX1/2 forced expression, neural differentiation efficiency assay Regenerative therapy Medium 36514370
2026 IRX1 suppresses breast cancer progression by inhibiting de novo fatty acid synthesis; mechanistically, IRX1 interacts with NME1 (confirmed by Co-IP), promotes NME1 nuclear localization, and the IRX1-NME1 complex transcriptionally downregulates ACACA (acetyl-CoA carboxylase alpha), reducing fatty acid synthesis. Co-immunoprecipitation (IRX1-NME1 interaction), nuclear localization assays, IRX1 overexpression/knockdown, ACACA expression analysis, de novo fatty acid synthesis assays, in vitro and in vivo tumor models Cell death & disease Medium 42225620
2019 IRX1 hypermethylation in heart failure suppresses CXCL14 expression; demethylation with 5-aza-2'-deoxycytidine restored IRX1 and CXCL14 expression and alleviated heart failure in a transverse aortic constriction (TAC) rat model. TAC rat model, 5-Aza treatment, Western blot, qRT-PCR, cardiac ultrasound, immunofluorescence, bioinformatic analysis Cell cycle (Georgetown, Tex.) Low 31640472
2019 miR-150 negatively regulates IRX1 expression in gastric cancer; miR-150 inhibition or IRX1 overexpression restricted proliferation, migration, and invasion while promoting apoptosis, with CXCL14 and NF-κB (p65) expression negatively correlated with IRX1 levels. miR-150 gain/loss-of-function, IRX1 overexpression/silencing, cell proliferation, colony formation, migration/invasion, apoptosis assays, in vivo xenograft IUBMB life Low 31846199
2025 Irx1 is expressed in M3, M4, and M5 ipRGC subtypes downstream of Tbr2; Irx1 ablation reduces Opn4 (melanopsin) expression specifically in M3, M4, and M5 ipRGCs without affecting the formation of Irx1-expressing ipRGCs, placing Irx1 in a Tbr2-dependent transcription cascade controlling ipRGC subtype fate and Opn4 expression. Irx1 conditional ablation in retinal development, Opn4 expression analysis by immunofluorescence/RNA, ipRGC subtype characterization bioRxivpreprint Low bio_10.1101_2025.04.29.651262

Source papers

Stage 0 corpus · 31 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2015 IRX1 hypomethylation promotes osteosarcoma metastasis via induction of CXCL14/NF-κB signaling. The Journal of clinical investigation 107 25822025
2013 HNF1B controls proximal-intermediate nephron segment identity in vertebrates by regulating Notch signalling components and Irx1/2. Development (Cambridge, England) 97 23362348
2010 Homeobox gene IRX1 is a tumor suppressor gene in gastric carcinoma. Oncogene 80 20440264
2011 IRX1 influences peritoneal spreading and metastasis via inhibiting BDKRB2-dependent neovascularization on gastric cancer. Oncogene 61 21602894
2018 Protein arginine methyltransferase 5-mediated epigenetic silencing of IRX1 contributes to tumorigenicity and metastasis of gastric cancer. Biochimica et biophysica acta. Molecular basis of disease 38 29802960
2010 HPV status-independent association of alcohol and tobacco exposure or prior radiation therapy with promoter methylation of FUSSEL18, EBF3, IRX1, and SEPT9, but not SLC5A8, in head and neck squamous cell carcinomas. Genes, chromosomes & cancer 37 20029986
2001 Irx1 and Irx2 expression in early lung development. Mechanisms of development 35 11472847
2017 Irx1 regulates dental outer enamel epithelial and lung alveolar type II epithelial differentiation. Developmental biology 30 28746823
2001 Expression pattern of Irx1 and Irx2 during mouse digit development. Mechanisms of development 25 11472848
2016 The IRX1/HOXA connection: insights into a novel t(4;11)- specific cancer mechanism. Oncotarget 24 27175594
2013 Hypermethylation of EBF3 and IRX1 genes in synovial fibroblasts of patients with rheumatoid arthritis. Molecules and cells 24 23456299
2014 A novel gain-of-function mutation of the proneural IRX1 and IRX2 genes disrupts axis elongation in the Araucana rumpless chicken. PloS one 22 25372603
2001 Identification and expression of zebrafish Iroquois homeobox gene irx1. Development genes and evolution 22 11685579
2017 Duplication events downstream of IRX1 cause North Carolina macular dystrophy at the MCDR3 locus. Scientific reports 21 28790370
2023 ADRA2A and IRX1 are putative risk genes for Raynaud's phenomenon. Nature communications 19 37828025
2013 Irx1 and Irx2 are coordinately expressed and regulated by retinoic acid, TGFβ and FGF signaling during chick hindlimb development. PloS one 19 23505533
2022 The Hematopoietic TALE-Code Shows Normal Activity of IRX1 in Myeloid Progenitors and Reveals Ectopic Expression of IRX3 and IRX5 in Acute Myeloid Leukemia. International journal of molecular sciences 16 35328612
2018 Six1 and Irx1 have reciprocal interactions during cranial placode and otic vesicle formation. Developmental biology 16 30529252
2020 HOXA9/IRX1 expression pattern defines two subgroups of infant MLL-AF4-driven acute lymphoblastic leukemia. Experimental hematology 15 33069783
2019 IRX1 hypermethylation promotes heart failure by inhibiting CXCL14 expression. Cell cycle (Georgetown, Tex.) 14 31640472
2019 Downregulated microRNA-150 upregulates IRX1 to depress proliferation, migration, and invasion, but boost apoptosis of gastric cancer cells. IUBMB life 13 31846199
2021 miR-646/TET1 mediated demethylation of IRX1 promoter upregulates HIST2H2BE and promotes the progression of invasive ductal carcinoma. Genomics 12 33667646
2018 Clinical significance of Iroquois Homeobox Gene - IRX1 in human glioma. Molecular medicine reports 8 29328446
2016 Identification of IRX1 as a Risk Locus for Rheumatoid Factor Positivity in Rheumatoid Arthritis in a Genome-Wide Association Study. Arthritis & rheumatology (Hoboken, N.J.) 8 26815016
2022 Variation of DNA methylation on the IRX1/2 genes is responsible for the neural differentiation propensity in human induced pluripotent stem cells. Regenerative therapy 7 36514370
2022 A ∼ 4.1 kb deletion in IRX1 gene upstream is completely associated with rumplessness in Piao chicken. Genomics 6 36306957
2025 Irx1 mechanisms for oral epithelial basal stem cell plasticity during reepithelialization after injury. JCI insight 4 39782692
2018 [Expression of IRX1 in cervical cancer and its correlation with clinical stage of cervical cancer]. Zhonghua yi xue za zhi 3 29374919
2022 IRX1 ameliorates sepsis-induced acute kidney injury in mice by promoting CXCL14. Allergologia et immunopathologia 2 36335463
2023 IRX1 is a novel gene, overexpressed in high-grade IDH-mutant astrocytomas. Pathology, research and practice 1 37116364
2026 IRX1 suppresses breast cancer progression by inhibiting fatty acid de novo synthesis through downregulating ACACA expression. Cell death & disease 0 42225620

Missed literature

Know a paper Affinage missed for IRX1? Flag it for the maintainers and the community.

No submissions yet.