Affinage

HOXA2

Homeobox protein Hox-A2 · UniProt O43364

Length
376 aa
Mass
41.0 kDa
Annotated
2026-04-28
68 papers in source corpus 38 papers cited in narrative 37 extracted findings

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

HOXA2 is a homeodomain transcription factor that functions as a selector gene specifying second pharyngeal arch (hyoid) identity and patterning dorsoventral neuronal subtypes in the developing hindbrain. HOXA2 binds Hox-Pbx bipartite response elements at target gene promoters and enhancers — directly activating Meox1, Pcp4, and SIRT1 while repressing Sox9, Cbfa1/Runx2, and BMP signaling components — to inhibit chondrogenesis, osteogenesis, and first-arch fate acquisition in cranial neural crest-derived mesenchyme (PMID:7903601, PMID:9636074, PMID:21245383, PMID:29184513, PMID:41466054). Its own expression is controlled by a modular cis-regulatory architecture including Krox20-dependent r3/r5 enhancers, a Hoxb1/Pbx-responsive r4 enhancer, Sox-dependent exonic r2 elements, and an AP-2-dependent neural crest enhancer, with epigenetic silencing via DNMT1-mediated promoter methylation and NSD2/H3K36me2 deposition (PMID:8625806, PMID:17113575, PMID:19104046, PMID:10068641, PMID:38996954). Post-translationally, HOXA2 transcriptional activity is attenuated by KPC2/PPP1CB-mediated nuclear export, which sequesters a stable cytoplasmic HOXA2 pool, and by RCHY1-directed proteasomal turnover that HOXA2 itself reciprocally counteracts to stabilize p53 (PMID:31323436, PMID:24244684). Homozygous loss-of-function mutations in the HOXA2 homeodomain cause autosomal recessive microtia in humans (PMID:18394579).

Mechanistic history

Synthesis pass · year-by-year structured walk · 15 steps
  1. 1993 High

    The fundamental question of what specifies second branchial arch skeletal identity was resolved: Hoxa2 knockout mice showed homeotic transformation of second-arch neural crest derivatives into first-arch elements, establishing Hoxa2 as the selector gene for hyoid identity.

    Evidence Two independent homologous recombination knockouts with skeletal and histological analysis in mouse

    PMID:7903600 PMID:7903601

    Open questions at the time
    • Mechanism by which Hoxa2 suppresses first-arch fate at the molecular level was unknown
    • Whether Hoxa2 acted during migration or differentiation was unresolved
    • Direct transcriptional targets not identified
  2. 1995 High

    The question of how Hoxa2 expression is spatially restricted across the hindbrain was addressed by identifying a modular cis-regulatory architecture: separate enhancers drive r2, r4, and caudal neuroepithelial expression, with a RARE essential for caudal domains, and Krox20 directly binding and activating the r3/r5 enhancer.

    Evidence Transgenic reporter assays with point mutagenesis (RARE, Krox20 sites) in mouse and chick; in vitro Krox20 binding assays

    PMID:7743939 PMID:8625806

    Open questions at the time
    • Identity of factors driving r2-specific expression unknown at this stage
    • Neural crest enhancer regulation not yet characterized
  3. 1998 High

    The downstream chondrogenic pathway was clarified: Hoxa2 restricts chondrogenesis by acting upstream of Sox9 induction and inhibits dermal bone formation by preventing Cbfa1 upregulation, explaining the ectopic cartilage and bone seen in knockouts.

    Evidence Hoxa2 knockout analysis with Sox9 misexpression, in situ hybridization, and immunohistochemistry

    PMID:9636074

    Open questions at the time
    • Whether Hoxa2 directly binds Sox9 or Cbfa1 regulatory elements was unknown
    • Signaling pathways mediating the anti-chondrogenic effect not identified
  4. 1999 High

    Two key regulatory and functional dimensions were established: AP-2 family transcription factors were shown to directly bind the neural crest enhancer of Hoxa2 (essential for NCC-specific expression), and Hoxa2/Hoxb2 compound mutants revealed cooperative control of dorsoventral neuronal patterning in the hindbrain beyond anteroposterior identity.

    Evidence Transgenic reporter mutagenesis with AP-2 co-transfection and AP-2α null analysis; Hoxa2/Hoxb2 double knockout with neuronal marker analysis

    PMID:10068641 PMID:10230789

    Open questions at the time
    • Which AP-2 family member is physiologically most relevant in vivo was unclear
    • Direct neuronal target genes of Hoxa2 in hindbrain DV patterning unidentified
  5. 2000 High

    Gain-of-function experiments resolved whether Hoxa2 is sufficient for fate specification: ectopic Hoxa2 in Xenopus first-arch at postmigratory stages caused homeotic jaw-to-hyoid transformation, demonstrating sufficiency, while chick experiments showed transformation required expression in both NCC and surrounding tissues.

    Evidence Inducible Hoxa2 gain-of-function in Xenopus; in ovo electroporation in chick with targeted vs. global expression

    PMID:11076757 PMID:11076758

    Open questions at the time
    • Environmental signals from non-NCC tissues that cooperate with Hoxa2 were uncharacterized
    • Whether Hoxa2 sufficiency extends to mammals was untested
  6. 2005 High

    Temporal conditional deletion showed that Hoxa2 is required in postmigratory cranial neural crest cells during differentiation rather than migration, proving hyoid NCCs retain plasticity and depend on continued Hoxa2 expression for their morphogenetic program.

    Evidence Cre-ERT2-based temporal Hoxa2 deletion after NCC migration with skeletal and molecular marker analysis

    PMID:16221728

    Open questions at the time
    • The precise developmental window of Hoxa2 requirement not fully delimited
    • Downstream effectors mediating postmigratory Hoxa2 function unknown
  7. 2006 High

    The r4-specific enhancer was shown to integrate Hoxa2 into auto/cross-regulatory Hox loops via three Hox/Pbx bipartite sites responding to HOXB1, and conditional knockouts revealed Hoxa2's role in somatosensory map formation — early expression prevents ectopic trigeminal projections while late expression organizes whisker-related barrelette maps.

    Evidence Binding/mutagenesis/transgenic validation of r4 enhancer; spatiotemporally controlled conditional knockout with axonal tracing and electrophysiology

    PMID:16902088 PMID:17113575

    Open questions at the time
    • Transcriptional targets mediating somatosensory map formation unidentified
    • Whether Hoxa2 acts cell-autonomously in PrV neurons not yet tested
  8. 2008 High

    Direct transcriptional targets began to be identified: Six2 was shown to be repressed by Hoxa2, Meox1 promoter was directly bound by Hoxa2 at two conserved sites, and cis-regulatory elements embedded in the Hoxa2 coding exon were found to contain Sox-dependent r2 enhancer and Hox/Pbx-responsive r4 elements, revealing an unusually complex self-regulatory architecture. A human HOXA2 homeodomain missense mutation (Q186K) was identified as causing autosomal recessive microtia.

    Evidence ChIP, promoter mutagenesis, double-mutant epistasis (Six2/Hoxa2, Meox1/2), transgenic reporters; human linkage analysis and sequencing

    PMID:18321982 PMID:18394579 PMID:18417536 PMID:19104046

    Open questions at the time
    • No biochemical confirmation that Q186K mutation reduces DNA binding
    • How Six2 repression versus Meox1 activation are achieved by the same factor unclear
  9. 2012 High

    Genome-wide ChIP-seq revealed HOXA2 binds thousands of sites enriched for Hox and Pbx-Hox motifs, with target genes enriched in Wnt signaling; canonical Wnt-β-catenin signaling was active in the Hoxa2 domain and lost in mutants, linking Hoxa2 to Wnt pathway regulation.

    Evidence ChIP-seq in mouse embryos with in vivo Wnt reporter and Hoxa2 mutant analysis

    PMID:22223247

    Open questions at the time
    • Which Wnt pathway genes are direct vs. indirect Hoxa2 targets was not distinguished
    • Whether Hoxa2 activates or permits Wnt signaling is mechanistically unclear
  10. 2013 Medium

    Post-translational regulation of HOXA2 was uncovered: HOXA2 interacts with the E3 ligase RCHY1 and 20S proteasome subunits, promoting RCHY1 degradation in a proteasome-dependent but ubiquitin-independent manner, which stabilizes p53. Additional targets Pcp4 and pinna morphogenesis through BMP/Eya1 were identified.

    Evidence Co-immunoprecipitation, proteasome inhibitor and ubiquitination assays; ChIP and gain-of-function for Pcp4; fate mapping with conditional gain/loss-of-function for pinna

    PMID:23671666 PMID:24067355 PMID:24244684

    Open questions at the time
    • Physiological relevance of HOXA2-RCHY1-p53 axis in vivo not demonstrated
    • RCHY1 degradation mechanism is non-canonical and awaits reconstitution with purified components
  11. 2015 High

    A cytoplasmic regulatory module was characterized: KPC2 binds HOXA2 and induces its nuclear export, diminishing transcriptional activity; gain-of-function in PrV neurons showed HOXA2 is sufficient to switch neuronal identity and coordinate topographic connectivity, and ectopic HOXA2 in PA1 CNCCs confirmed context-dependent homeotic transformations.

    Evidence Co-precipitation, BiFC, nuclear/cytoplasmic fractionation for KPC2; conditional gain-of-function with axonal tracing for neuronal identity; cell-type-specific CNCC gain-of-function

    PMID:25889273 PMID:26303204 PMID:26489473

    Open questions at the time
    • Whether KPC2-mediated export occurs in cranial NCCs in vivo unknown
    • Signals triggering KPC2-HOXA2 interaction not identified
  12. 2019 Medium

    The KPC2/PPP1CB/HOXA2 trimeric complex was defined: PPP1CB cooperates with KPC2 to promote HOXA2 nuclear export while de-ubiquitinating and stabilizing cytoplasmic HOXA2, establishing a mechanism for maintaining a cytoplasmic HOXA2 reservoir.

    Evidence Co-immunoprecipitation, co-localization, transcriptional reporter assays, ubiquitination assays, nuclear/cytoplasmic fractionation

    PMID:31323436

    Open questions at the time
    • In vivo relevance of cytoplasmic HOXA2 pool not demonstrated
    • Signals that mobilize cytoplasmic HOXA2 back to the nucleus are unknown
    • Single-lab finding without independent replication
  13. 2017 High

    The anti-osteogenic mechanism was clarified: Hoxa2 inhibits BMP signaling-dependent osteoblast differentiation in palatal mesenchyme, and pharmacological BMP inhibition rescues the Hoxa2-null palatal differentiation phenotype, establishing epistasis between Hoxa2 and BMP signaling.

    Evidence Hoxa2 knockout primary MEPM cell culture with dorsomorphin rescue, Western blot, Alizarin Red staining

    PMID:29184513

    Open questions at the time
    • Whether Hoxa2 directly represses BMP ligand/receptor transcription or acts post-transcriptionally is unresolved
    • Palate-specific vs. general anti-osteogenic mechanism not distinguished
  14. 2024 Medium

    Epigenetic regulation of HOXA2 itself was demonstrated: NSD2-mediated H3K36me2 at the HOXA2 locus suppresses its transcription, inhibiting osteogenic differentiation of bone marrow mesenchymal stem cells, while HOTAIRM1 lncRNA promotes HOXA2 expression by blocking DNMT1-mediated promoter methylation.

    Evidence ChIP for H3K36me2/NSD2 and DNMT1; shRNA/overexpression with osteogenic assays; micro-CT in OVX mouse model; bisulfite sequencing

    PMID:32324272 PMID:38996954

    Open questions at the time
    • Whether NSD2 and DNMT1 pathways act independently or converge on HOXA2 regulation is unknown
    • In vivo validation in craniofacial tissues not performed
  15. 2025 Medium

    A non-craniofacial transcriptional target was identified: HOXA2 directly binds the SIRT1 promoter to enhance SIRT1 transcription, which deacetylates ATF6 to reduce ER stress and renal fibrosis, with HOXA2 itself suppressed by DNMT1-mediated methylation in fibrotic kidney.

    Evidence ChIP of HOXA2 at SIRT1 promoter, AAV-mediated HOXA2 overexpression in UUO mouse model, deacetylation assays

    PMID:41466054

    Open questions at the time
    • Whether HOXA2 endogenously functions in adult kidney physiology is unconfirmed
    • Relevance of HOXA2-SIRT1 axis outside the UUO model not tested

Open questions

Synthesis pass · forward-looking unresolved questions
  • Key open questions remain: how HOXA2 simultaneously activates some targets (Meox1, SIRT1) and represses others (Sox9, BMP pathway genes) through the same DNA-binding domain; whether the KPC2/PPP1CB cytoplasmic reservoir has developmental significance in vivo; and whether HOXA2 heterodimerization with HOXA3 or other paralogues modulates target selectivity genome-wide.
  • No structural data for HOXA2-cofactor complexes on DNA
  • Dual activator/repressor mechanism not resolved
  • In vivo function of cytoplasmic HOXA2 pool untested

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0140110 transcription regulator activity 7 GO:0003677 DNA binding 5
Localization
GO:0005634 nucleus 5 GO:0005829 cytosol 2
Pathway
R-HSA-74160 Gene expression (Transcription) 9 R-HSA-1266738 Developmental Biology 7 R-HSA-112316 Neuronal System 3 R-HSA-162582 Signal Transduction 2
Partners
EGR2HOXA3HOXB1KPC2MEIS1PBX1PPP1CBRCHY1

Evidence

Reading pass · 37 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
1993 Hoxa2 acts as a selector gene in the second branchial arch: homozygous Hoxa2 knockout mice show homeotic transformation of second arch mesenchymal neural crest cell (NCC) derivatives into first arch skeletal elements, demonstrating Hoxa2 specifies second arch identity in NCC-derived mesenchyme. Homologous recombination knockout, skeletal analysis, histology Cell High 7903600 7903601
1996 Segmental expression of Hoxa2 in rhombomeres 3 and 5 is directly regulated by the zinc-finger transcription factor Krox-20 (Egr2), which binds two sites within the Hoxa2 r3/r5 enhancer; mutation of these Krox20 binding sites abolishes r3/r5 enhancer activity, and ectopic Krox20 in r4 transactivates the Hoxa2 reporter. Transgenic lacZ reporter analysis, in vitro binding/competition assays with bacterially expressed Krox20, site-directed mutagenesis, ectopic Krox20 expression Development High 8625806
1994 Hoxa2 expression is independently regulated in the neural tube and cranial neural crest cells; the decision to downregulate Hoxa2 in r2-derived neural crest (but maintain it in r4-derived neural crest) is intrinsic to the premigratory crest cell population, as shown by rhombomere transposition experiments in chick. In situ hybridization, rhombomere grafting/transposition experiments in chick embryos Development High 7600967
1995 Three independent enhancers control Hoxa2 expression: two mediate hindbrain-specific expression in rhombomere 2 and rhombomere 4 respectively, and a retinoic acid response element (RARE) in the Hoxa1/Hoxa2 region is essential for neuroepithelial expression caudal to r4; point mutations in the RARE abolish caudal neuroepithelial expression. Transgenic mouse reporter assays, point mutagenesis of RARE, reporter gene analysis in Drosophila Development High 7743939
1998 Hoxa2 restricts chondrogenesis in the second branchial arch by acting upstream of Sox9 induction; in Hoxa2-/- embryos, Sox9 expression domain shifts into the normal Hoxa2 domain, ectopic chondrogenesis occurs, and Cbfa1 is upregulated, indicating Hoxa2 also inhibits dermal bone formation by preventing Cbfa1 induction. Hoxa2 knockout analysis, Sox9 misexpression, in situ hybridization, immunohistochemistry Development High 9636074
1999 AP-2 family transcription factors directly bind a cis-element in the Hoxa2 neural crest enhancer and are required for neural-crest-specific Hoxa2 expression; mutation or deletion of the AP-2 binding site abolishes reporter expression in cranial neural crest but not hindbrain, and AP-2 family members trans-activate the enhancer in cell culture and transgenic embryos. Transgenic reporter analysis with deletion and mutational mapping, cell culture co-transfection, AP-2alpha null mutant analysis Development High 10068641
1999 Hoxa2 and Hoxb2 control both anteroposterior and dorsoventral patterning during hindbrain neurogenesis; they differentially regulate gene expression in rhombomere-specific D-V-restricted domains of neuronal progenitors and subtypes, and can functionally synergize in controlling ventral neuronal subtypes in r3. Single and double Hoxa2/Hoxb2 knockout analysis, in situ hybridization, immunohistochemistry of neuronal markers Neuron High 10230789
2000 Ectopic Hoxa2 induction at postmigratory stages in Xenopus is sufficient to cause homeotic transformation of jaw elements toward hyoid morphology (reverse of knockout phenotype), demonstrating Hoxa2 alone is sufficient to specify hyoid fate even after NCC migration. Inducible Hoxa2 gain-of-function system in Xenopus, skeletal staining, stage-specific induction Development High 11076758
2000 Overexpression of Hoxa2 globally in chick first branchial arch (neural crest plus surrounding tissue) transforms first arch cartilages into second arch elements; targeting neural crest alone is insufficient for transformation, indicating Hoxa2 requires environmental cues and acts during differentiation rather than migration. In ovo electroporation of Hoxa2, skeletal staining, targeted vs. global overexpression comparison Development High 11076757
2000 Hoxa1 activity is required to set the anterior limit of Hoxb1 expression at the r3/r4 boundary; failure in Hoxa1 mutants initiates a cascade of misexpressions affecting r2-r5, and Hoxa1/Hoxa2 double mutants reveal both independent and synergistic functions in hindbrain patterning. Single and double Hoxa1/Hoxa2 knockout, in situ hybridization for multiple hindbrain markers, genetic epistasis Development High 10662633
1996 Hoxa2 functions upstream of the Eph receptor tyrosine kinase MDK1 in the hindbrain morphogenetic signaling cascade; in Hoxa2 null mutant mice, MDK1 expression is selectively lost in rhombomere 3, placing MDK1 downstream of Hoxa2. In situ hybridization of MDK1 in Hoxa2 null mutant mice, zebrafish orthologue cloning Developmental Biology Medium 8806819
2006 A conserved intronic r4 enhancer of Hoxa2 contains three bipartite Hox/Pbx binding sites (PH1-PH3) and one Pbx-Prep/Meis site that cooperate to drive r4 expression; mutation of these sites abolishes enhancer activity, and the enhancer responds to ectopic HOXB1 expression, identifying Hoxa2 as a direct Hoxb1 target integrated into auto- and cross-regulatory Hox loops. In vitro binding studies, mutational analysis, transgenic reporter assays in mouse and chicken, ectopic HOXB1 expression Developmental Biology High 17113575
2006 Hoxa2 has a rhombomere-dependent role in facial somatosensory map formation: early Hoxa2 expression prevents ectopic trigeminal nerve projection to cerebellum, while late expression in the principal sensory nucleus promotes selective arborization of whisker-related afferents and topographic thalamic connectivity; Hoxa2 inactivation abolishes whisker-related maps. Conditional Hoxa2 knockout (spatial and temporal), axonal tracing, electrophysiology, genetic fate mapping Science High 16902088
2008 A Hox-Pbx responsive cis-regulatory element embedded in the coding sequence of Hoxa2 (within an ultraconserved element) is responsive to paralog group 1 and 2 Hox proteins and Pbx co-factors, cooperates with the intronic r4 enhancer, and is required for r4-specific expression in chick hindbrain. Cell transfection assays, chromatin immunoprecipitation (ChIP), chick hindbrain electroporation, sequence conservation analysis Nucleic Acids Research High 18417536
2008 A cis-regulatory module embedded in the second coding exon of Hoxa2 consists of two Sox binding sites plus additional elements that direct strong r2-specific hindbrain expression. Deletion analysis, transgenic reporter assays, Sox binding site mutagenesis PNAS High 19104046
2008 Six2 is a direct downstream target of Hoxa2 in vivo; Hoxa2 binds the Meox1 proximal promoter at two conserved sites required for activation, and in the absence of Hoxa2, Six2 is ectopically expressed and contributes to the Hoxa2 mutant phenotype through the insulin-like growth factor pathway. ChIP, promoter reporter assays, Hoxa2/Six2 double mutant analysis, genetic epistasis Development High 18321982
2005 Hoxa2 is selectively required in cranial neural crest cells (NCCs) for hyoid skeletal patterning; temporal Cre-ERT2-mediated Hoxa2 deletion after NCC migration still causes homeotic transformation of hyoid to mandibular derivatives, showing hyoid NCCs retain plasticity post-migration and require Hoxa2 as integral to their morphogenetic program. Conditional Cre-ERT2-based temporal Hoxa2 deletion, skeletal analysis, in situ hybridization of downstream targets Development High 16221728
2012 Genome-wide ChIP-seq mapping of Hoxa2 binding in mouse embryos shows Hoxa2 has large genome coverage with thousands of potential targets; sequence analysis identifies Hox and Pbx-Hox motifs at binding sites; Hoxa2 binding targets are enriched for Wnt-signaling pathway genes, and canonical Wnt-β-catenin signaling is active specifically in the Hoxa2 expression domain and undetectable in Hoxa2 mutants. ChIP-seq, in vivo Wnt-reporter assay, Hoxa2 mutant analysis Nucleic Acids Research High 22223247
2011 Meox1 is a direct transcriptional target of Hoxa2: Hoxa2 binds the Meox1 proximal promoter by ChIP, two conserved Hoxa2 binding sites are required for Hoxa2-dependent activation of the Meox1 promoter, Meox1 is genetically downstream of Hoxa2, and loss of Meox1/Meox2 causes malformation of second arch skeletal elements patterned by Hoxa2. ChIP, promoter mutagenesis, promoter reporter assays, Meox1/2 double mutant analysis Molecular and Cellular Biology High 21245383
2013 Hoxa2 interacts with 20S proteasome subunits and the E3 ubiquitin ligase RCHY1 (PIRH2), promotes proteasome-dependent but ubiquitin-independent degradation of RCHY1, consequently alters RCHY1-mediated ubiquitination of p53, and stabilizes p53. Co-immunoprecipitation, proteasome inhibitor assays, ubiquitination assays, p53 stabilization assays PLoS One Medium 24244684
2015 KPC2, an adapter protein of the KPC ubiquitin-ligase complex, is a genuine interactor of Hoxa2 (confirmed by co-precipitation and bimolecular fluorescence complementation); KPC2 diminishes Hoxa2 transcriptional activity and induces nuclear exit (cytoplasmic relocalization) of Hoxa2. Co-precipitation, bimolecular fluorescence complementation (BiFC), gene expression analysis, nuclear/cytoplasmic fractionation Biochimica et Biophysica Acta Medium 26303204
2015 The Hoxa2-mediated degradation of RCHY1 involves both 19S and 20S proteasome complexes and requires both the Hoxa2 homeodomain and C-terminal moiety; the homeodomain alone can mediate RCHY1 binding but is necessary but not sufficient for RCHY1 degradation; this activity is evolutionarily conserved among vertebrates. Deletion mutagenesis, co-immunoprecipitation, proteasome complex inhibitor assays PLoS One Medium 26496426
2019 HOXA2 interacts with PPP1CB (PP1 phosphatase catalytic subunit) and KPC2 to form a complex that co-localizes in the cytoplasm; PPP1CB and KPC2 together inhibit HOXA2 transcriptional activity by promoting its nuclear export while simultaneously favoring HOXA2 de-ubiquitination and stabilization, establishing a cytoplasmic HOXA2 store. Co-immunoprecipitation, co-localization assays, transcriptional reporter assays, nuclear/cytoplasmic fractionation, ubiquitination assays Biochimica et Biophysica Acta Gene Regulatory Mechanisms Medium 31323436
2015 Ectopic Hoxa2 expression in first arch (Hox-negative) cranial neural crest cells is sufficient to transform ventral PA1 derivatives (proximal Meckel's cartilage, malleus) into PA2-like structures (supernumerary styloid process), while causing developmental impairment in other CNCC subpopulations, revealing context-dependent Hoxa2 function. Conditional Hoxa2 gain-of-function in specific CNCC subpopulations, Edn1-Dlx5/6 pathway manipulation, skeletal analysis Developmental Biology High 25889273
2015 Ectopic Hoxa2 expression in dorsal PrV neurons is sufficient to attract whisker-related afferents, induce asymmetrical dendrite arbors, allow ectopic barrelette map formation, and redirect thalamic axon targeting and refinement, demonstrating Hoxa2 is sufficient to switch neuronal identity and coordinate input-output topographic connectivity. Conditional Hoxa2 gain-of-function in dPrV neurons, axonal tracing, DiI labeling, immunohistochemistry Cell Reports High 26489473
2013 Genetic fate mapping shows the mouse auricle (pinna) derives entirely from Hoxa2-expressing second pharyngeal arch neural crest mesenchyme; conditional ectopic Hoxa2 expression in first arch neural crest is sufficient to induce complete pinna duplication and EAC loss. Hoxa2 partly controls pinna morphogenesis through BMP signaling and Eya1 expression. Genetic fate mapping (Cre-loxP), conditional gain- and loss-of-function, skeletal analysis, pathway marker analysis Development High 24067355
2008 A homozygous missense mutation in the HOXA2 homeodomain (p.Q186K) causes autosomal recessive microtia; homology modeling predicts loss of a hydrogen bond to DNA phosphate, suggesting impaired DNA-binding activity. Human genetics (linkage analysis, sequencing), homology modeling of homeodomain-DNA interaction American Journal of Human Genetics Medium 18394579
2017 Hoxa2 regulates palatal osteogenic differentiation by inhibiting BMP signaling-dependent osteoblast markers; Hoxa2-/- palatal mesenchyme shows increased Runx2, Sp7, ALP, and canonical BMP signaling, and blocking BMP signaling with dorsomorphin in Hoxa2-/- cells restores proliferation and differentiation to wild-type levels. Hoxa2 knockout analysis, primary MEPM cell culture, BMP pathway inhibition (dorsomorphin), Alizarin Red staining, immunostaining, Western blot Frontiers in Physiology High 29184513
2009 Hoxa2 plays a direct role in palatal development: Hoxa2 is expressed in the palatal mesenchyme and epithelium, Hoxa2-/- palates show decreased fusion even in tongue-free organ culture, and Hoxa2 represses downstream targets Msx1, Bmp4, Barx1, and Ptx1 within the palate. Hoxa2 null palate organ culture, antisense retroviral knockdown, immunohistochemistry, in situ hybridization Developmental Dynamics Medium 19653318
2007 Persistent Hoxa2 expression in chondrogenic cells (Col2a1-expressing) causes chondrodysplasia with delayed cartilage hypertrophy, mineralization, and ossification, without affecting condensation or migration; this demonstrates Hoxa2 has an anti-chondrogenic activity in differentiation that is distinct from its patterning function. Cre-mediated conditional Hoxa2 misexpression in chondrogenic lineage, histology, immunohistochemistry, cell proliferation assays Differentiation High 17359301
2020 lncRNA HOTAIRM1 promotes osteogenesis of dental follicle stem cells by epigenetically regulating HOXA2: HOTAIRM1 inhibits DNMT1 enrichment on the HOXA2 promoter CpG islands, leading to promoter hypomethylation and HOXA2 induction. lncRNA knockdown/overexpression, DNMT1 ChIP, bisulfite sequencing, osteogenic differentiation assays Journal of Cellular Physiology Medium 32324272
2020 Two HOXA2 nonsense mutations impair activation of the long-range HMX1 enhancer, as shown by dual luciferase reporter assays, linking HOXA2 loss-of-function to defective HMX1 regulation in microtia. Dual luciferase reporter assays, next-generation sequencing Gene Medium 32649979
2013 Hoxa2 binds Pcp4 chromatin and regulates Pcp4 expression in the second branchial arch; ectopic Hoxa2 is sufficient to induce Pcp4 expression in anterior first arch cells, identifying Pcp4 as a direct Hoxa2 target gene defining second arch molecular identity. ChIP, in situ hybridization, gain-of-function Hoxa2 electroporation PLoS One Medium 23671666
1999 Hoxa2, when co-expressed with Pbx and Meis cofactors in P19 cells, reduces the frequency of spontaneous neuronal differentiation; similarly, Hoxa2 plus cofactors in chick neural crest cells reduces neurogenesis in the trigeminal ganglion, indicating Hoxa2 represses neurogenic potential of cranial neural crest cells. P19 cell culture overexpression, chick neural crest electroporation, neuronal differentiation quantification Developmental Biology Medium 18164701
2021 HOXA2 and HOXA3 can heterodimerise in vitro; the highest enriched binding motif in HOXA2 ChIP-seq peaks is not recognised by HOXA2 in vitro, highlighting that in vivo HOXA2 binding context differs from in vitro sequence preferences. In vitro binding assays (EMSA/equivalent), ChIP-seq data comparison, heterodimerization assay Journal of Developmental Biology Medium 34940502
2024 NSD2-mediated H3K36me2 dimethylation on the HOXA2 locus transcriptionally downregulates Hoxa2 expression and thereby inhibits osteogenic differentiation of bone marrow mesenchymal stem cells; ChIP confirmed NSD2/H3K36me2 enrichment at Hoxa2, and Hoxa2 knockdown or NSD2 overexpression both inhibit osteoblast markers Runx2 and BSP. ChIP (H3K36me2, NSD2), shRNA knockdown, lentiviral overexpression, luciferase reporter, micro-CT in OVX mouse model Cellular Signalling Medium 38996954
2025 HOXA2 binds the SIRT1 promoter to enhance SIRT1 transcription and deacetylase activity; SIRT1 in turn deacetylates ATF6 causing its downregulation, thereby reducing ER stress and renal fibrosis. DNMT1-mediated promoter methylation was identified as a mechanism for HOXA2 suppression in fibrosis. ChIP (HOXA2 binding to SIRT1 promoter), AAV-mediated HOXA2 overexpression in UUO mouse model, deacetylation assays, methylation analysis Communications Biology Medium 41466054

Source papers

Stage 0 corpus · 68 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
1993 A homeotic transformation is generated in the rostral branchial region of the head by disruption of Hoxa-2, which acts as a selector gene. Cell 536 7903601
1993 Hoxa-2 mutant mice exhibit homeotic transformation of skeletal elements derived from cranial neural crest. Cell 475 7903600
1994 Hoxa-2 expression in normal and transposed rhombomeres: independent regulation in the neural tube and neural crest. Development (Cambridge, England) 215 7600967
1995 Evolutionary-conserved enhancers direct region-specific expression of the murine Hoxa-1 and Hoxa-2 loci in both mice and Drosophila. Development (Cambridge, England) 185 7743939
1998 Hoxa-2 restricts the chondrogenic domain and inhibits bone formation during development of the branchial area. Development (Cambridge, England) 178 9636074
2000 Ectopic Hoxa2 induction after neural crest migration results in homeosis of jaw elements in Xenopus. Development (Cambridge, England) 165 11076758
1996 Segmental expression of Hoxa-2 in the hindbrain is directly regulated by Krox-20. Development (Cambridge, England) 163 8625806
1999 Hoxa2 and Hoxb2 control dorsoventral patterns of neuronal development in the rostral hindbrain. Neuron 157 10230789
2000 Homeotic transformation of branchial arch identity after Hoxa2 overexpression. Development (Cambridge, England) 151 11076757
2000 Roles of Hoxa1 and Hoxa2 in patterning the early hindbrain of the mouse. Development (Cambridge, England) 141 10662633
2006 Hoxa2- and rhombomere-dependent development of the mouse facial somatosensory map. Science (New York, N.Y.) 107 16902088
2005 Temporal requirement of Hoxa2 in cranial neural crest skeletal morphogenesis. Development (Cambridge, England) 102 16221728
1999 Regulation of Hoxa2 in cranial neural crest cells involves members of the AP-2 family. Development (Cambridge, England) 98 10068641
1996 The expression pattern of the mouse receptor tyrosine kinase gene MDK1 is conserved through evolution and requires Hoxa-2 for rhombomere-specific expression in mouse embryos. Developmental biology 79 8806819
2013 Mouse Hoxa2 mutations provide a model for microtia and auricle duplication. Development (Cambridge, England) 75 24067355
2008 A mutation in HOXA2 is responsible for autosomal-recessive microtia in an Iranian family. American journal of human genetics 75 18394579
1999 Compensatory defects associated with mutations in Hoxa1 restore normal palatogenesis to Hoxa2 mutants. Development (Cambridge, England) 68 10529419
2006 Expression of Hoxa2 in rhombomere 4 is regulated by a conserved cross-regulatory mechanism dependent upon Hoxb1. Developmental biology 66 17113575
2012 Genome-wide occupancy links Hoxa2 to Wnt-β-catenin signaling in mouse embryonic development. Nucleic acids research 60 22223247
2008 An ultraconserved Hox-Pbx responsive element resides in the coding sequence of Hoxa2 and is active in rhombomere 4. Nucleic acids research 56 18417536
2008 A regulatory module embedded in the coding region of Hoxa2 controls expression in rhombomere 2. Proceedings of the National Academy of Sciences of the United States of America 54 19104046
2007 Fate-mapping the mammalian hindbrain: segmental origins of vestibular projection neurons assessed using rhombomere-specific Hoxa2 enhancer elements in the mouse embryo. The Journal of neuroscience : the official journal of the Society for Neuroscience 52 17804628
2005 Hoxa2 knockdown in Xenopus results in hyoid to mandibular homeosis. Developmental dynamics : an official publication of the American Association of Anatomists 48 16222714
2008 Six2 functions redundantly immediately downstream of Hoxa2. Development (Cambridge, England) 41 18321982
2002 Conservation and diversity in the cis-regulatory networks that integrate information controlling expression of Hoxa2 in hindbrain and cranial neural crest cells in vertebrates. Developmental biology 41 12027433
2006 Evolution of cis elements in the differential expression of two Hoxa2 coparalogous genes in pufferfish (Takifugu rubripes). Proceedings of the National Academy of Sciences of the United States of America 40 16569696
2013 HOXA2 haploinsufficiency in dominant bilateral microtia and hearing loss. Human mutation 38 23775976
2020 lncRNA HOTAIRM1 promotes osteogenesis of hDFSCs by epigenetically regulating HOXA2 via DNMT1 in vitro. Journal of cellular physiology 37 32324272
2009 Ascorbic acid reverses valproic acid-induced inhibition of hoxa2 and maintains glutathione homeostasis in mouse embryos in culture. Cellular and molecular neurobiology 35 19655241
2019 Study of Promoter Methylation Patterns of HOXA2, HOXA5, and HOXA6 and Its Clinicopathological Characteristics in Colorectal Cancer. Frontiers in oncology 34 31165042
2015 Distinct effects of Hoxa2 overexpression in cranial neural crest populations reveal that the mammalian hyomandibular-ceratohyal boundary maps within the styloid process. Developmental biology 31 25889273
2001 Differences in Krox20-dependent regulation of Hoxa2 and Hoxb2 during hindbrain development. Developmental biology 31 11336508
2002 Targeted insertion results in a rhombomere 2-specific Hoxa2 knockdown and ectopic activation of Hoxa1 expression. Developmental dynamics : an official publication of the American Association of Anatomists 30 12412013
2015 Hoxa2 Selects Barrelette Neuron Identity and Connectivity in the Mouse Somatosensory Brainstem. Cell reports 29 26489473
2017 Hoxa2 Inhibits Bone Morphogenetic Protein Signaling during Osteogenic Differentiation of the Palatal Mesenchyme. Frontiers in physiology 27 29184513
2007 Distinct roles of Hoxa2 and Krox20 in the development of rhythmic neural networks controlling inspiratory depth, respiratory frequency, and jaw opening. Neural development 27 17897445
2007 Expression of Hoxa2 in cells entering chondrogenesis impairs overall cartilage development. Differentiation; research in biological diversity 25 17359301
2011 Transient activation of meox1 is an early component of the gene regulatory network downstream of hoxa2. Molecular and cellular biology 22 21245383
2016 Identification of a second HOXA2 nonsense mutation in a family with autosomal dominant non-syndromic microtia and distinctive ear morphology. Clinical genetics 21 27503514
2010 Mutational analysis of HOXA2 and SIX2 in a Bronx population with isolated microtia. International journal of pediatric otorhinolaryngology 21 20542577
2013 The homeodomain transcription factor Hoxa2 interacts with and promotes the proteasomal degradation of the E3 ubiquitin protein ligase RCHY1. PloS one 17 24244684
2020 Identification of loss-of-function HOXA2 mutations in Chinese families with dominant bilateral microtia. Gene 16 32649979
2001 Coordinated expression of Hoxa2, Hoxd1 and Pax6 in the developing diencephalon. Neuroreport 15 11209945
2009 Hoxa2 plays a direct role in murine palate development. Developmental dynamics : an official publication of the American Association of Anatomists 14 19653318
1999 Differential expression of Hoxa-2 protein along the dorsal-ventral axis of the developing and adult mouse spinal cord. Developmental dynamics : an official publication of the American Association of Anatomists 14 10536059
2004 The Hoxa2 enhancer 2 contains a critical Hoxa2 responsive regulatory element. Biochemical and biophysical research communications 12 15033486
2000 Temporal and spatial expression of Hoxa-2 during murine palatogenesis. Cellular and molecular neurobiology 12 10789828
2007 Altered neuronal lineages in the facial ganglia of Hoxa2 mutant mice. Developmental biology 11 18164701
2015 KPC2 relocalizes HOXA2 to the cytoplasm and decreases its transcriptional activity. Biochimica et biophysica acta 10 26303204
2010 Expressing Hoxa2 across the entire endochondral skeleton alters the shape of the skeletal template in a spatially restricted fashion. Differentiation; research in biological diversity 10 20034726
2015 Analyses of fugu hoxa2 genes provide evidence for subfunctionalization of neural crest cell and rhombomere cis-regulatory modules during vertebrate evolution. Developmental biology 9 26632170
2016 Mutational analysis of GSC, HOXA2 and PRKRA in 106 Chinese patients with microtia. International journal of pediatric otorhinolaryngology 7 28109504
2015 Molecular Analysis of the HOXA2-Dependent Degradation of RCHY1. PloS one 7 26496426
2019 HOXA2 activity regulation by cytoplasmic relocation, protein stabilization and post-translational modification. Biochimica et biophysica acta. Gene regulatory mechanisms 6 31323436
2013 Molecular study of a Hoxa2 gain-of-function in chondrogenesis: a model of idiopathic proportionate short stature. International journal of molecular sciences 6 24129174
2004 Early stages of oligodendrocyte development in the embryonic murine spinal cord proceed normally in the absence of Hoxa2. Glia 6 15326611
2025 Epigenetic regulation of HOXA2 expression affects tumor progression and predicts breast cancer patient survival. Cell death and differentiation 5 39833374
2024 NSD2-mediated H3K36me2 exacerbates osteoporosis via activation of hoxa2 in bone marrow mesenchymal stem cells. Cellular signalling 5 38996954
1999 Analysis of murine HOXA-2 activity in Drosophila melanogaster. Developmental genetics 5 10322642
2021 Silencing Hoxa2 reverses dexamethasone-induced dysfunction of MC3T3-E1 osteoblasts and osteoporosis in rats. Advances in clinical and experimental medicine : official organ Wroclaw Medical University 4 33984197
2011 Conditional Tet-regulated over-expression of Hoxa2 in CG4 cells increases their proliferation and delays their differentiation into oligodendrocyte-like cells expressing myelin basic protein. Cellular and molecular neurobiology 4 21479584
2021 Molecular Characterization of HOXA2 and HOXA3 Binding Properties. Journal of developmental biology 3 34940502
2016 Mutational Analysis of TCOF1, GSC, and HOXA2 in Patients With Treacher Collins Syndrome. The Journal of craniofacial surgery 2 27526242
2013 Differential distribution of the Ca (2+) regulator Pcp4 in the branchial arches is regulated by Hoxa2. PloS one 2 23671666
2024 Association between mandibular prognathism and Matrilin-1, bone morphogenic protein, Tyr67Asn, homeobox protein hox-A2, Rho-GTPase activating protein, and Myosin 1H genes in the Indian population. Folia medica 1 39257274
2016 Functional and Comparative Genomics of Hoxa2 Gene cis-Regulatory Elements: Evidence for Evolutionary Modification of Ancestral Core Element Activity. Journal of developmental biology 1 29615583
2011 Postnatal growth defect in mice upon persistent Hoxa2 expression in the chondrogenic cell lineage. Differentiation; research in biological diversity 1 22093256
2025 HOXA2 exerts anti-renal fibrosis effects through reducing endoplasmic reticulum stress via the upregulation of SIRT1. Communications biology 0 41466054