Affinage

ARMCX3

Armadillo repeat-containing X-linked protein 3 · UniProt Q9UH62

Length
379 aa
Mass
42.5 kDa
Annotated
2026-06-09
19 papers in source corpus 10 papers cited in narrative 10 extracted findings
Cross-family judge vs UniProt: Affinage preferred faithfulness: 5/5 claims corpus-supported (100%)

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

ARMCX3 (Alex3) is an integral membrane protein of the mitochondrial outer membrane that controls mitochondrial dynamics and trafficking, particularly in neurons (PMID:22569362, PMID:19304657). It assembles into the Kinesin/Miro1/Trak2 motor adaptor complex in a Ca2+-dependent manner, positioning it as a regulator of mitochondrial movement (PMID:22569362), and it further recruits Gαq into this complex to transduce GPCR signals onto the transport machinery independently of the canonical PLCβ pathway; CNS-specific loss of ARMCX3 abolishes Gαq-mediated control of mitochondrial trafficking and dendritic growth and causes ER stress, neuronal and motor neuron death, and severe motor deficits (PMID:38320000). ARMCX3 protein stability is regulated by the non-canonical Wnt/PKC pathway, which drives its degradation and thereby modulates mitochondrial morphology (PMID:23844091). Beyond its trafficking role, ARMCX3 interacts with the transcription factors Sox10 and SOX9: it binds Sox10 at the outer mitochondrial membrane and potentiates Sox10-dependent transactivation without intrinsic transcriptional activity (PMID:19304657), and its interaction with SOX9 drives hepatic cell proliferation, with ARMCX3 knockout protecting mice against high-fat-diet-induced NAFLD and chemically induced hepatocarcinogenesis (PMID:33807672). ARMCX3 also acts as a negative regulator of white adipose tissue browning and mitochondrial oxidative activity, with its expression repressed by thermogenic stimulation and induced by obesity (PMID:35705702).

Mechanistic history

Synthesis pass · year-by-year structured walk · 9 steps
  1. 2009 Medium

    Established the first molecular partner of ARMCX3 by showing it is an outer mitochondrial membrane protein that binds the transcription factor Sox10 and potentiates Sox10-driven transcription, linking a mitochondrial protein to gene regulation.

    Evidence Co-IP, membrane fractionation, and luciferase reporter assays in neuronal-like cell lines

    PMID:19304657

    Open questions at the time
    • Mechanism by which a membrane-anchored protein influences nuclear transactivation not defined
    • Single-lab interaction without reciprocal in vivo validation
  2. 2012 High

    Defined ARMCX3's core cellular function by placing it within the Kinesin/Miro/Trak2 motor adaptor complex and showing Ca2+-dependent regulation of mitochondrial trafficking in neurons.

    Evidence Subcellular fractionation, reciprocal Co-IP with Miro and Trak2, live-imaging of mitochondrial trafficking with overexpression/knockdown

    PMID:22569362

    Open questions at the time
    • Structural basis of Ca2+ sensing within the complex unresolved
    • Did not address upstream signals controlling complex assembly
  3. 2013 Medium

    Identified an upstream regulatory input controlling ARMCX3 by showing the non-canonical Wnt/PKC pathway degrades the protein and thereby modulates mitochondrial morphology.

    Evidence Wnt treatment and PKC pharmacological inhibition with immunoblot and mitochondrial morphology readout in HEK293 cells

    PMID:23844091

    Open questions at the time
    • Specific E3 ligase/degradation machinery not identified
    • Performed in non-neuronal overexpression system
  4. 2016 Medium

    Connected ARMCX3's mitochondrial localization to developmental phenotypes, showing it regulates neural progenitor proliferation and inhibits Wnt-β-catenin signaling in a localization-dependent manner.

    Evidence In ovo electroporation of knockdown/overexpression and localization mutants in chick neural tube with proliferation and differentiation markers

    PMID:26973462

    Open questions at the time
    • Molecular link between mitochondrial anchoring and Wnt inhibition not defined
    • Single in vivo model
  5. 2021 High

    Extended ARMCX3 function to disease pathophysiology by demonstrating it drives hepatic tumorigenesis under lipotoxicity through a SOX9 interaction, with knockout being protective.

    Evidence Inducible ARMCX3 KO mouse with high-fat-diet/diethylnitrosamine carcinogenesis, HCC cell line gain/loss-of-function, and Co-IP for SOX9

    PMID:33807672

    Open questions at the time
    • How mitochondrial ARMCX3 engages the SOX9 transcriptional program mechanistically unclear
    • Relationship between the Sox10 and SOX9 interactions not addressed
  6. 2022 Medium

    Revealed a metabolic role for ARMCX3 as a negative regulator of adipose browning and mitochondrial oxidative activity responsive to thermogenic and obesogenic signals.

    Evidence Armcx3 KO mice, adenoviral overexpression and siRNA in brown adipocytes, qPCR, mitochondrial respiration assays, histology

    PMID:35705702

    Open questions at the time
    • Direct molecular effectors of thermogenic gene repression not identified
    • Link to its motor-complex function in adipocytes unexplored
  7. 2024 High

    Integrated ARMCX3 into GPCR signaling by showing it recruits Gαq to the Miro1/Trak2 complex to arrest mitochondrial transport independently of PLCβ, with conditional knockout producing severe neurodegenerative phenotypes.

    Evidence Mitoproteome mass spectrometry, Co-IP, CNS-specific conditional KO mouse, live-imaging of trafficking, dendritic and histological analyses

    PMID:38320000

    Open questions at the time
    • Biochemical mechanism by which Gαq engagement halts the motor not resolved
    • Receptors upstream of the Gαq input not defined
  8. 2024 Low

    Proposed transcriptional/post-transcriptional control of Armcx3 expression via a Prx II–ATF3–miR-181b-5p axis affecting mitochondrial transport.

    Evidence RNA-seq, Prx II knockdown/overexpression in HT22 cells, bioinformatics, miR-181b-5p target validation

    PMID:38637880

    Open questions at the time
    • Primarily transcriptomic/bioinformatic with limited direct validation for ARMCX3
    • Causal contribution of each node to ARMCX3 function untested
  9. 2024 Low

    Linked ARMCX3 to ROS signaling in regulating neural differentiation and inflammation in dental pulp stem cells.

    Evidence Lentiviral knockdown/overexpression in hDPSCs with ROS measurement and ROS-inhibitor rescue, qRT-PCR, ELISA

    PMID:39296219

    Open questions at the time
    • Mechanism upstream of ROS not defined
    • Single-lab gain/loss-of-function without genetic rescue

Open questions

Synthesis pass · forward-looking unresolved questions
  • How ARMCX3's dual roles — as a mitochondrial motor adaptor and as a partner of transcription factors (Sox10, SOX9) — are mechanistically coordinated, and what the structural basis of its Ca2+- and Gαq-dependent control of the Miro1/Trak2 complex is, remain unresolved.
  • No structural model of the ARMCX3/Miro1/Trak2/Gαq complex
  • Mechanism connecting mitochondrial anchoring to transcriptional partner regulation undefined

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0060090 molecular adaptor activity 2 GO:0098772 molecular function regulator activity 2
Localization
GO:0005739 mitochondrion 3
Pathway
R-HSA-9609507 Protein localization 2 R-HSA-162582 Signal Transduction 1
Complex memberships
Miro1/Trak2/Kinesin motor adaptor complex

Evidence

Reading pass · 10 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2012 ARMCX3 (Alex3) localizes to mitochondria and regulates mitochondrial dynamics and trafficking in neurons. Alex3 physically interacts with the Kinesin/Miro/Trak2 complex in a Ca2+-dependent manner, placing it in the motor adaptor complex that controls mitochondrial movement. Subcellular fractionation/localization, co-immunoprecipitation of Alex3 with Miro and Trak2, overexpression/knockdown with mitochondrial trafficking readout in neurons Nature Communications High 22569362
2009 ARMCX3 is an integral membrane protein of the mitochondrial outer membrane that physically interacts with the transcription factor Sox10. In the cytoplasm, Sox10 is peripherally associated with the mitochondrial outer membrane, and overexpression of ARMCX3 increases the amount of mitochondrially associated Sox10. ARMCX3 lacks intrinsic transcriptional activity but enhances Sox10-mediated transactivation of the nicotinic acetylcholine receptor alpha3 and beta4 subunit gene promoters. Co-immunoprecipitation (Sox10–ARMCX3 interaction), membrane fractionation (integral membrane protein characterization), luciferase reporter assays (transactivation), overexpression studies in neuronal-like cell lines The Journal of Biological Chemistry Medium 19304657
2013 The non-canonical Wnt/PKC pathway regulates mitochondrial dynamics by inducing degradation of Alex3 (ARMCX3). Wnt treatment attenuates Alex3-induced mitochondrial aggregation by reducing Alex3 protein levels; the canonical Wnt pathway does not affect this, but the Wnt/PKC non-canonical pathway controls both mitochondrial aggregation and Alex3 protein stability. Overexpression of Alex3 in HEK293 cells with Wnt treatment, protein level analysis (immunoblot), pharmacological inhibition of PKC pathway, mitochondrial morphology readout PLoS ONE Medium 23844091
2016 In chick spinal cord, ARMCX3 overexpression regulates neural progenitor proliferation and neural maturation, and these phenotypic effects require its mitochondrial localization. ARMCX3 acts as an inhibitor of Wnt-β-catenin signaling in neural development. In ovo electroporation of shRNA (knockdown) and overexpression constructs in chick neural tube, mitochondrial localization mutants, BrdU/EdU proliferation assays, neuronal differentiation markers Frontiers in Cellular Neuroscience Medium 26973462
2017 ARMCX3 (Alex3) overexpression in non-small cell lung cancer cells suppresses invasion and migration by downregulating phospho-AKT and Slug and upregulating E-cadherin, placing ARMCX3 upstream of the AKT/Slug/E-cadherin axis. Overexpression in lung cancer cell lines, invasion/migration assays (Transwell), immunoblot for p-AKT, Slug, E-cadherin Tumour Biology Low 28705116
2021 ARMCX3 mediates hepatic tumorigenesis under dietary lipotoxicity. ARMCX3 knockout in mice protected against high-fat-diet-induced NAFLD and chemically induced hepatocarcinogenesis, promoting apoptosis and macrophage infiltration. SOX9 was identified as a mediator of ARMCX3 effects in hepatic cells, with the SOX9–ARMCX3 interaction required for ARMCX3-driven hepatic cell proliferation. Inducible ARMCX3 knockout mouse model, high-fat diet + diethylnitrosamine carcinogenesis model, HCC cell line knockdown/overexpression, co-immunoprecipitation (ARMCX3–SOX9 interaction), viability/clonality/migration assays Cancers High 33807672
2022 ARMCX3 is a negative regulator of white adipose tissue browning. Armcx3-KO mice show induced WAT browning, and adenoviral overexpression of ARMCX3 in differentiating brown adipocytes downregulates thermogenesis-related genes and reduces mitochondrial oxidative activity. Armcx3 expression is repressed by cold or β3-adrenergic thermogenic stimulation and upregulated by obesity. Armcx3 knockout mice (adipose tissue characterization), adenoviral overexpression in brown adipocyte cultures, siRNA knockdown, gene expression (qPCR), mitochondrial respiration assay, histology International Journal of Obesity Medium 35705702
2024 ARMCX3 (Alex3) forms a mammalian-specific mitochondrial complex with Gαq and the Miro1/Trak2 adaptor complex. Gαq activation inhibits mitochondrial trafficking in neurons independently of the canonical PLCβ pathway. CNS-specific Alex3 knockout mice showed that Alex3 is required for Gαq-mediated effects on mitochondrial trafficking and dendritic growth. Alex3-deficient mice had elevated ER stress response proteins, increased neuronal death, motor neuron loss, and severe motor deficits. Mitoproteome/mass spectrometry (Gαq–Alex3 interaction), co-immunoprecipitation, CNS-specific conditional Alex3 knockout mouse, live-imaging of mitochondrial trafficking, dendritic complexity analysis, histological assessment of neuronal death and motor neuron loss Science Signaling High 38320000
2024 A regulatory axis involving Prx II, the transcription factor ATF3, and miR-181b-5p collectively modulates Armcx3 expression, which is implicated in mitochondrial transport. Prx II deficiency reduces Armcx3 levels via this pathway in neuronal (HT22) cells. RNA sequencing, Prx II knockdown/overexpression in HT22 cells, bioinformatic pathway analysis, miR-181b-5p target validation Cell Communication and Signaling Low 38637880
2024 ARMCX3 knockdown in dental pulp stem cells (hDPSCs) accelerates neural differentiation and reduces inflammatory cytokine levels under LPS-induced inflammation. ARMCX3 overexpression increases ROS production, and ROS inhibition reverses the effects of ARMCX3 overexpression, indicating ARMCX3 regulates neural differentiation and inflammation at least partly through ROS signaling. Lentiviral knockdown and overexpression in hDPSCs, ROS measurement (specific kits), immunofluorescence, qRT-PCR, ELISA, ROS inhibitor rescue experiment Heliyon Low 39296219

Source papers

Stage 0 corpus · 19 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2012 The Eutherian Armcx genes regulate mitochondrial trafficking in neurons and interact with Miro and Trak2. Nature communications 89 22569362
2001 ALEX1, a novel human armadillo repeat protein that is expressed differentially in normal tissues and carcinomas. Biochemical and biophysical research communications 58 11162520
2022 Screening of crosstalk and pyroptosis-related genes linking periodontitis and osteoporosis based on bioinformatics and machine learning. Frontiers in immunology 42 35990678
2009 The armadillo repeat-containing protein, ARMCX3, physically and functionally interacts with the developmental regulatory factor Sox10. The Journal of biological chemistry 32 19304657
2021 Whole-genome association analyses of sleep-disordered breathing phenotypes in the NHLBI TOPMed program. Genome medicine 26 34446064
2013 The non-canonical Wnt/PKC pathway regulates mitochondrial dynamics through degradation of the arm-like domain-containing protein Alex3. PloS one 24 23844091
2016 Function of Armcx3 and Armc10/SVH Genes in the Regulation of Progenitor Proliferation and Neural Differentiation in the Chicken Spinal Cord. Frontiers in cellular neuroscience 18 26973462
2021 GPRASP/ARMCX Protein Family: Potential Involvement in Health and Diseases Revealed by their Novel Interacting Partners. Current topics in medicinal chemistry 15 33267763
2022 Diverse and mobile: eccDNA-based identification of carrot low-copy-number LTR retrotransposons active in callus cultures. The Plant journal : for cell and molecular biology 14 35426957
2017 Alex3 suppresses non-small cell lung cancer invasion via AKT/Slug/E-cadherin pathway. Tumour biology : the journal of the International Society for Oncodevelopmental Biology and Medicine 11 28705116
2021 ARMCX3 Mediates Susceptibility to Hepatic Tumorigenesis Promoted by Dietary Lipotoxicity. Cancers 10 33807672
2024 A mammalian-specific Alex3/Gαq protein complex regulates mitochondrial trafficking, dendritic complexity, and neuronal survival. Science signaling 5 38320000
2024 Regulatory role of PDK1 via integrated gene analysis of mitochondria-immune response in periodontitis. Gene 5 38657876
2024 ARMCX3 regulates ROS signaling, affects neural differentiation and inflammatory microenvironment in dental pulp stem cells. Heliyon 5 39296219
2019 Epigenome- and Transcriptome-wide Changes in Muscle Stem Cells from Low Birth Weight Men. Endocrine research 5 31566019
2025 ITGA1, the alpha 1 subunit of integrin receptor, is a novel marker of drug-resistant senescent melanoma cells in vitro. Archives of toxicology 4 40202610
2025 Novel small non-coding RNAs of Epstein-Barr virus upregulated upon lytic reactivation aid in viral genomic replication and virion production. mBio 3 40197026
2024 Exploring the role of Prx II in mitigating endoplasmic reticulum stress and mitochondrial dysfunction in neurodegeneration. Cell communication and signaling : CCS 3 38637880
2022 The armadillo-repeat containing X-linked protein 3, ARMCX3, is a negative regulator of the browning of adipose tissue associated with obesity. International journal of obesity (2005) 3 35705702

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