Affinage

NOXA1

NADPH oxidase activator 1 · UniProt Q86UR1

Length
476 aa
Mass
50.9 kDa
Annotated
2026-06-10
19 papers in source corpus 17 papers cited in narrative 17 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

NOXA1 is the cytosolic activator subunit (p67phox homologue) of the NOX1 NADPH oxidase complex, where it serves as the central driver of regulated superoxide production across vascular, renal, and epithelial tissues (PMID:16814099). NOXA1 directly engages NOX1 through its activation domain, and a peptide mimicking this domain (NoxA1ds) selectively disrupts the NOX1–NOXA1 interface and blocks NOX1-derived superoxide without affecting NOX2, NOX4, NOX5, or xanthine oxidase (PMID:24187133). Complex assembly is gated by phosphorylation of the catalytic subunit itself: PKCβ1 phosphorylates NOX1 at Thr429 to promote its association with the NOXA1 activation domain, an interaction required for oxidase assembly and ROS-dependent vascular smooth muscle cell migration (PMID:25228390). Conversely, multi-site phosphorylation of NOXA1 restrains activity—PKA phosphorylates Ser172/Ser461 to drive 14-3-3ζ binding and dissociation of NOXA1 from the NOX1 complex, while MAPK (Ser282) and PKC/PKA (Ser172) phosphorylation reduce NOXA1 binding to both NOX1 and Rac1, basally suppressing constitutive activity (PMID:17913709, PMID:20110267). The NOXO1–NOXA1 module is recruited by PKC phosphorylation of NOXO1 at Thr341, and NOXA1's SH3 domain modulates the kinetics of active complex formation (PMID:23957209, PMID:17602954). c-Src phosphorylation of NOXA1 at Tyr110 (and of Tks4 at Tyr508) couples the oxidase to the Tks4/Tks5 invadopodial scaffolds, driving ROS-dependent invadopodia formation and ECM degradation in colon cancer (PMID:20943948). Physiologically, NOXA1-dependent NOX1 activity drives KLF4-mediated VSMC phenotypic switching during atherosclerosis (PMID:30576919) and mediates angiotensin II–dependent activation of the renal epithelial sodium channel (ENaC), contributing to sodium handling and blood pressure control (PMID:36201326, PMID:34714114). In airway epithelium NOXA1 instead acts as an inhibitory regulator of DUOX1, with calcium-induced conformational change relieving this constraint (PMID:18606821).

Mechanistic history

Synthesis pass · year-by-year structured walk · 17 steps
  1. 2006 Medium

    Established NOXA1 as the functional activator subunit of the smooth muscle NADPH oxidase, answering whether the p67phox homologue drives ROS in non-phagocytic cells.

    Evidence Antisense knockdown and fluorescent fusion localization with ROS chemiluminescence in mouse VSMC

    PMID:16814099

    Open questions at the time
    • Did not define the molecular interface with NOX1
    • Single lab, antisense rather than genetic deletion
  2. 2007 High

    Defined a negative-regulatory mechanism whereby PKA phosphorylation of NOXA1 recruits 14-3-3 and dissociates it from NOX1, linking cAMP signaling to oxidase shutdown.

    Evidence Site-directed mutagenesis of Ser172/Ser461, co-IP, and cAMP manipulation in HEK293 and colon cell lines

    PMID:17913709

    Open questions at the time
    • Did not map which interface region 14-3-3 occludes
    • Physiological cAMP-elevating stimulus not identified
  3. 2007 Medium

    Resolved the role of the NOXA1 SH3 domain, showing it is dispensable for activation but tunes assembly kinetics and is the target of a transdominant inhibitory splice variant.

    Evidence Deletion/insertion mutagenesis and kinetic superoxide assays in K562 cells expressing NOX1/NOXO1, with pulldowns

    PMID:17602954

    Open questions at the time
    • In vivo relevance of the NOXA1(inhib) splice variant unknown
    • Single cell model
  4. 2008 Medium

    Revealed a context-specific inhibitory role: NOXA1 constrains DUOX1 in airway epithelium, with calcium relieving the constraint, distinguishing it from its NOX1-activating function.

    Evidence siRNA knockdown, DUOX1 reconstitution, and domain mutagenesis with H2O2 measurement in airway epithelial models

    PMID:18606821

    Open questions at the time
    • Structural basis of NOXA1–DUOX1 constraint not defined
    • How calcium triggers dissociation mechanistically unresolved
  5. 2008 Medium

    Extended NOXA1's requirement for stimulus-induced ROS to endothelial cells downstream of LOX-1 signaling.

    Evidence siRNA knockdown with DHE ROS assay in human vascular endothelial cells under ox-LDL and angiotensin II

    PMID:18568954

    Open questions at the time
    • Did not establish the NOX isoform partner in endothelium
    • No reciprocal validation of pathway
  6. 2010 High

    Mapped basal inhibitory phosphorylation of NOXA1 by MAPK and PKC/PKA and tied it to reduced NOX1 and Rac1 binding, defining how constitutive oxidase output is held in check.

    Evidence In vitro kinase assays, phosphopeptide mapping, mutagenesis (S172A/S282A), and binding/ROS assays in HEK293

    PMID:20110267

    Open questions at the time
    • Did not resolve whether these sites act sequentially or independently in vivo
  7. 2010 High

    Connected NOXA1 to invadopodia by showing c-Src phosphorylation at Tyr110 couples it to Tks4/Tks5 scaffolds to drive localized ROS and ECM degradation in colon cancer.

    Evidence Phosphomimetic/unphosphorylatable mutant rescue, co-IP, and invadopodia/ECM degradation assays in colon cancer cells

    PMID:20943948

    Open questions at the time
    • In vivo tumor relevance not tested
    • Spatial coupling of ROS to ECM proteases not mechanistically resolved
  8. 2010 Medium

    Quantified the NOXO1–p22phox interaction biophysically and showed the NOXO1–NOXA1 module differs molecularly from the phagocytic p47phox–p67phox pair.

    Evidence Isothermal titration calorimetry with isolated SH3 domains and C-terminal tail

    PMID:20454568

    Open questions at the time
    • No functional or mutational validation in cells
    • Full-length complex architecture not determined
  9. 2012 High

    Distinguished NOXA1 from p67phox kinetically, showing it activates NOX2 less efficiently in a purified system.

    Evidence Reconstituted cell-free system with purified cytochrome b558, Rac(Q61L), NOXO1, and kinetic/FAD-affinity analysis

    PMID:22244833

    Open questions at the time
    • Physiological significance of NOXA1–NOX2 cross-activation unclear
  10. 2013 Medium

    Showed PKC phosphorylation of the NOXO1 partner at Thr341 promotes NOXO1–NOXA1 assembly required for PMA-stimulated NOX1 superoxide.

    Evidence In vitro PKC kinase assay, T341A mutagenesis, pulldown, and superoxide assay

    PMID:23957209

    Open questions at the time
    • Cell-type and stimulus generality not established
  11. 2013 High

    Identified the NOXA1 activation domain as the critical, NOX1-selective assembly interface using a disrupting peptide.

    Evidence Cell-free reconstitution, FRET binding disruption, and multiple ROS readouts with the NoxA1ds peptide

    PMID:24187133

    Open questions at the time
    • Atomic-resolution structure of the interface not solved
    • Therapeutic delivery of NoxA1ds not addressed
  12. 2014 High

    Demonstrated that PKCβ1 phosphorylation of NOX1 at Thr429 promotes NOX1–NOXA1 association required for assembly and VSMC migration, providing a TNFα-responsive activation switch on the catalytic subunit.

    Evidence Mass spectrometry phosphosite mapping, T429 mutagenesis, ITC, PKCβ1 siRNA, and VSMC migration/ROS assays

    PMID:25228390

    Open questions at the time
    • Interplay between NOX1 Thr429 phosphorylation and inhibitory NOXA1 phosphorylation not integrated
  13. 2018 High

    Placed NOXA1-dependent NOX1 activity upstream of KLF4-driven VSMC phenotypic switching in atherosclerosis using cell-type-specific genetics.

    Evidence SMC-specific Noxa1 knockout in Apoe-/- mice, injury and Western-diet models, ROS, and KLF4/VCAM1/CCL2/MMP2 readouts

    PMID:30576919

    Open questions at the time
    • Mechanism linking ROS to KLF4 induction not dissected
  14. 2022 High

    Established NOXA1/NOX1 as the mediator of angiotensin II–dependent ENaC activation in renal principal cells, defining a physiological sodium-handling role.

    Evidence Principal-cell-specific Noxa1 conditional KO, patch-clamp on split-open tubules, and ML171/losartan pharmacology

    PMID:36201326

    Open questions at the time
    • Molecular link between ROS and ENaC gating not resolved
  15. 2022 Medium

    Connected NOXA1 to systemic blood pressure and sex-specific sodium retention through effects on renal ENaC.

    Evidence Global Noxa1 knockout with telemetry, ANG II infusion, immunofluorescence, and renal-cell siRNA ENaC assays

    PMID:34714114

    Open questions at the time
    • Basis of sex-specific difference unexplained
    • Global KO confounds tissue-specific contributions
  16. 2025 Low

    Proposed NOXA1 as a ferroptosis suppressor in radiotherapy-resistant colorectal cancer via the SLC7A11/GPX4 axis.

    Evidence siRNA knockdown in CRC lines with ROS, ferroptosis, and radiosensitivity assays plus GSVA

    PMID:40084254

    Open questions at the time
    • No mechanistic link between NOXA1 and SLC7A11/GPX4 regulation
    • Single lab, single knockdown approach
  17. 2025 Low

    Proposed a transcriptional and autophagy-regulatory role for NOXA1 downstream of ERVWE1/USF2 in schizophrenia-related neuronal pathology.

    Evidence Neuronal cellular assays for LC3B/SQSTM1/PINK1/Parkin/PDHA1 with bioinformatics and clinical serum measures

    PMID:40419114

    Open questions at the time
    • Direct role of NOXA1 in autophagy versus upstream regulatory context not dissected
    • Mixed bioinformatic/cellular evidence, single lab

Open questions

Synthesis pass · forward-looking unresolved questions
  • How the multiple phosphorylation switches on NOXA1, NOX1, and NOXO1 are integrated in space and time to set oxidase output in a given tissue remains unresolved.
  • No atomic structure of the assembled NOX1–NOXO1–NOXA1–Rac complex
  • Crosstalk between activating (NOX1 Thr429) and inhibitory (NOXA1 Ser172/282/461) phosphorylation not integrated
  • Mechanism linking localized ROS to downstream effectors (KLF4, ENaC, SLC7A11) undefined

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0098772 molecular function regulator activity 5 GO:0060089 molecular transducer activity 3
Localization
GO:0005886 plasma membrane 3 GO:0005829 cytosol 1
Pathway
R-HSA-162582 Signal Transduction 3 R-HSA-8953897 Cellular responses to stimuli 2
Complex memberships
NOX1 NADPH oxidase complex

Evidence

Reading pass · 17 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2007 PKA phosphorylates NoxA1 at Ser172 and Ser461, which enhances NoxA1 binding to 14-3-3 proteins (specifically 14-3-3ζ) and induces dissociation of NoxA1 from the Nox1 complex at the plasma membrane, thereby inhibiting Nox1-dependent ROS production. Elevation of cAMP inhibits, and PKA inhibition enhances, Nox1-dependent ROS production through effects on NoxA1. Site-directed mutagenesis, transfected HEK293 cell model, endogenous Nox1 in colon cell lines, co-immunoprecipitation, cAMP manipulation The Journal of biological chemistry High 17913709
2010 MAP kinases phosphorylate NoxA1 at Ser282, and PKC and PKA phosphorylate NoxA1 at Ser172. These phosphorylations occur basally and down-regulate constitutive NOX1 activity. Single mutants S172A and S282A up-regulate NOX1-derived ROS, and double mutant S172A/S282A further increases ROS. Phosphorylation at these sites decreases NoxA1 binding to both NOX1 and Rac1. In vitro kinase assays, site-directed mutagenesis, phosphopeptide mapping, transfected HEK293 cell model, ROS measurement FASEB journal High 20110267
2010 c-Src phosphorylates NoxA1 at Tyr110 and Tks4 at Tyr508; abolishing these phosphorylations blocks the NoxA1–Tks4 interaction and decreases Nox1-dependent ROS generation. Phosphomimetic mutants of both NoxA1 and Tks4 rescue SrcYF-induced invadopodia formation and ECM degradation, while unphosphorylatable mutants block it. NoxA1 interaction with Tks4 and Tks5 scaffold proteins is Src-activity dependent. Site-directed mutagenesis (phosphomimetic and unphosphorylatable mutants), co-immunoprecipitation, ROS measurement, invadopodia/ECM degradation assays in human colon cancer cells Molecular biology of the cell High 20943948
2006 Noxa1 (the p67phox homologue) is expressed in the cytosolic fraction of mouse vascular smooth muscle cells (VSMC) and co-localizes to the membrane when co-expressed with Noxo1. Antisense knockdown of Noxa1 attenuates basal and agonist (bFGF, EGF)-induced ROS production in mouse VSMC, establishing Noxa1 as the central activator subunit of the smooth muscle NADPH oxidase. Western blot, immunohistochemistry, fluorescent fusion protein localization, antisense knockdown, L012 chemiluminescence ROS assay Free radical biology & medicine Medium 16814099
2013 A peptide mimicking the putative activation domain of NOXA1 (NoxA1ds) potently and selectively inhibits Nox1-derived superoxide production in a reconstituted cell-free system and in whole cells, with no effect on Nox2, Nox4, Nox5, or xanthine oxidase. FRET experiments show NoxA1ds disrupts the direct binding interaction between Nox1 and NOXA1, identifying the NOXA1 activation domain as the critical interface for NOX1 complex assembly. Cell-free reconstituted Nox1 system, cytochrome c reduction, Amplex Red fluorescence, EPR, FRET (Nox1-YFP/NOXA1-CFP), ELISA, FRAP, confocal microscopy with FITC-labeled peptide The Journal of biological chemistry High 24187133
2010 The isolated tandem SH3 domains of NOXO1 bind p22phox with high affinity, likely in a superSH3 conformation, and the C-terminal tail of NOXO1 competes for p22phox binding, thereby contributing to NOX1 regulation. The NOXO1–NOXA1 interaction differs molecularly from the p47phox–p67phox interaction of the phagocytic oxidase, suggesting functional differences between the two systems. Isothermal titration calorimetry (ITC), quantitative characterization of protein-protein interactions in vitro PloS one Medium 20454568
2007 The NOXA1 SH3 domain is not required for NOX1 activation but modulates the kinetics of active complex formation: truncated NOXA1 lacking SH3 activates NOX1 at an accelerated rate compared to wild-type. A heptapeptide insertion into the SH3 domain (from the NOXA1(inhib) splice variant) inhibits NOXA1 activity by ~90%, acts as a transdominant inhibitor, and abrogates SH3 domain binding to NOXO1 and p47phox. Transfection into K562 cells stably expressing NOX1/NOXO1, kinetic superoxide generation assays, deletion and insertion mutagenesis, pulldown binding assays Free radical biology & medicine Medium 17602954
2008 In airway epithelial cells, Noxa1 associates with plasma membrane-bound Duox (Duox1) and acts as an inhibitory regulator of Duox activity. Calcium flux promotes Duox activation by causing dissociation of Noxa1 from Duox. Knockdown of Noxa1 increases basal H2O2 generation. Mutation of a proline-rich domain in the Duox C-terminus (a potential Noxa1-SH3 interaction motif) up-regulates H2O2 production, and the Noxa1 activation domain is not required for Duox regulation. siRNA knockdown, Duox1 reconstitution in model cell lines, mutagenesis of Noxa1 and Duox1, H2O2 measurement, mucociliary airway epithelium model The Journal of biological chemistry Medium 18606821
2013 PKC-mediated phosphorylation of Noxo1 at Thr341 (directly phosphorylated by PKC in vitro) facilitates Noxo1 interaction with Noxa1, and this interaction is required for PMA-dependent enhancement of Nox1 superoxide production. Alanine substitution at Thr341 reduces both Noxo1 phosphorylation and Nox1-catalyzed superoxide production. In vitro PKC kinase assay, site-directed mutagenesis (T341A), pulldown binding assay between Noxo1 and Noxa1, superoxide production assay The FEBS journal Medium 23957209
2014 PKCβ1 phosphorylates Nox1 at Thr429 in response to TNFα, and this phosphorylation facilitates association of Nox1 with the NoxA1 activation domain. This Nox1-NoxA1 interaction is necessary for NADPH oxidase complex assembly, ROS production, and vascular smooth muscle cell migration. Mass spectrometry (phosphosite identification), pharmacological PKC inhibition, siRNA silencing of PKCβ1, site-directed mutagenesis (T429), isothermal titration calorimetry (NoxA1ds binding), VSMC migration assay, ROS measurement Circulation research High 25228390
2008 siRNA-mediated knockdown of NOXA1 in human vascular endothelial cells potently decreases ROS generation induced by oxidized LDL and angiotensin II, establishing NOXA1 as essential for NAD(P)H oxidase-dependent ROS production in endothelial cells downstream of LOX-1 signaling. siRNA knockdown, dihydroethidium ROS assay, RT-PCR Endothelium Medium 18568954
2012 In a pure reconstituted cell-free system using purified cytochrome b558 (Nox2+p22phox), Rac(Q61L), and Noxo1, Noxa1 activates Nox2 with lower efficiency than p67phox: higher EC50, one-third Vmax, lower FAD affinity, and reduced stability of the active complex. These kinetic differences distinguish Noxa1 from the canonical Nox2 activator p67phox. In vitro reconstituted cell-free NADPH oxidase system with purified proteins, kinetic analysis, FAD affinity measurement Archives of biochemistry and biophysics High 22244833
2018 SMC-specific genetic deletion of Noxa1 in Apoe-/- mice reduces vascular ROS, attenuates TNFα-induced VSMC proliferation and migration, and decreases expression of KLF4 transcription factor and its downstream targets VCAM1, CCL2, and MMP2 in atherosclerotic lesions, placing NOXA1-dependent NOX1 activity upstream of KLF4-mediated VSMC phenotypic switching to macrophage-like cells. Conditional SMC-specific Noxa1 knockout mouse, endovascular injury model, Western diet atherosclerosis model, immunofluorescence, ROS measurement, VSMC proliferation/migration assays Redox biology High 30576919
2022 Principal cell-specific Noxa1 knockout mice fail to increase ENaC activity in response to angiotensin II, and pharmacological NOX1 inhibition (ML171) abolishes ANG II-dependent ENaC stimulation, establishing that NOXA1/NOX1 signaling mediates ANG II-dependent activation of the epithelial sodium channel in renal principal cells of the distal nephron. Principal cell-specific Noxa1 conditional knockout mice, patch-clamp electrophysiology on freshly isolated split-open tubules, ML171 pharmacological inhibition, losartan AT1R blockade American journal of physiology. Renal physiology High 36201326
2022 NOXA1 is present in Henle's thick ascending limb and distal nephron epithelial cells. Systemic Noxa1 deletion reduces basal systolic blood pressure and attenuates ANG II-induced increases in renal ENaC levels, ENaC activation in collecting duct principal cells, and sodium retention, with sex-specific differences (males more affected than females). Noxa1 global knockout mice, telemetry blood pressure measurement, ANG II infusion, immunofluorescence, siRNA knockdown of Noxa1 in renal epithelial cell line, ENaC activity assay Antioxidants & redox signaling Medium 34714114
2025 Knockdown of Noxa1 in radiotherapy-resistant colorectal cancer cells decreases expression of SLC7A11 and GPX4, increases cellular ROS levels, induces ferroptosis, and sensitizes cells to radiotherapy, placing NOXA1 upstream of the glutathione metabolic pathway (SLC7A11/GPX4 axis) as a suppressor of ferroptosis. siRNA knockdown of Noxa1 in CRC cell lines, Western blot for SLC7A11 and GPX4, ROS measurement, ferroptosis assay, radiotherapy sensitivity assay, GSVA pathway analysis International journal of medical sciences Low 40084254
2025 ERVWE1 (human endogenous retrovirus W envelope protein) upregulates USF2 transcription factor, which enhances NOXA1 transcription. NOXA1 in turn promotes macroautophagy (increased LC3B II/I ratio, enhanced autophagosome formation, reduced SQSTM1) and inhibits micromitophagy by suppressing PINK1, Parkin, and PDHA1 expression in the context of schizophrenia-related pathology. Cellular and molecular experiments in neuronal context, LC3B assay, autophagosome formation assay, SQSTM1/PINK1/Parkin/PDHA1 expression, bioinformatics (GSE53987), clinical serum measurements Virologica Sinica Low 40419114

Source papers

Stage 0 corpus · 19 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2010 c-Src-mediated phosphorylation of NoxA1 and Tks4 induces the reactive oxygen species (ROS)-dependent formation of functional invadopodia in human colon cancer cells. Molecular biology of the cell 92 20943948
2007 Regulation of Nox1 activity via protein kinase A-mediated phosphorylation of NoxA1 and 14-3-3 binding. The Journal of biological chemistry 85 17913709
2006 Noxa1 is a central component of the smooth muscle NADPH oxidase in mice. Free radical biology & medicine 75 16814099
2013 Selective recapitulation of conserved and nonconserved regions of putative NOXA1 protein activation domain confers isoform-specific inhibition of Nox1 oxidase and attenuation of endothelial cell migration. The Journal of biological chemistry 65 24187133
2018 NOXA1-dependent NADPH oxidase regulates redox signaling and phenotype of vascular smooth muscle cell during atherogenesis. Redox biology 58 30576919
2010 Phosphorylation of NADPH oxidase activator 1 (NOXA1) on serine 282 by MAP kinases and on serine 172 by protein kinase C and protein kinase A prevents NOX1 hyperactivation. FASEB journal : official publication of the Federation of American Societies for Experimental Biology 52 20110267
2010 Regulation of NOXO1 activity through reversible interactions with p22 and NOXA1. PloS one 51 20454568
2008 Essential role of NOXA1 in generation of reactive oxygen species induced by oxidized low-density lipoprotein in human vascular endothelial cells. Endothelium : journal of endothelial cell research 39 18568954
2008 Inhibitory action of NoxA1 on dual oxidase activity in airway cells. The Journal of biological chemistry 35 18606821
2014 Phosphorylation of Nox1 regulates association with NoxA1 activation domain. Circulation research 30 25228390
2013 Phosphorylation of Noxo1 at threonine 341 regulates its interaction with Noxa1 and the superoxide-producing activity of Nox1. The FEBS journal 28 23957209
2022 Renal NOXA1/NOX1 Signaling Regulates Epithelial Sodium Channel and Sodium Retention in Angiotensin II-induced Hypertension. Antioxidants & redox signaling 25 34714114
2007 NOX1 NADPH oxidase regulation by the NOXA1 SH3 domain. Free radical biology & medicine 18 17602954
2012 Noxa1 as a moderate activator of Nox2-based NADPH oxidase. Archives of biochemistry and biophysics 16 22244833
2023 Reactivity of renal and mesenteric resistance vessels to angiotensin II is mediated by NOXA1/NOX1 and superoxide signaling. American journal of physiology. Renal physiology 7 36759130
2022 NOXA1-dependent NADPH oxidase 1 signaling mediates angiotensin II activation of the epithelial sodium channel. American journal of physiology. Renal physiology 7 36201326
2021 MiR-155 acts as an inhibitory factor in atherosclerosis-associated arterial pathogenesis by down-regulating NoxA1 related signaling pathway in ApoE-/- mouse. Cardiovascular diagnosis and therapy 7 33708473
2025 Human endogenous retrovirus W family envelope protein (ERVWE1) regulates macroautophagy activation and micromitophagy inhibition via NOXA1 in schizophrenia. Virologica Sinica 3 40419114
2025 NADPH oxidase activator 1 (NOXA1) suppresses ferroptosis and radiosensitization in colorectal cancer. International journal of medical sciences 1 40084254

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