Affinage

CNNM4

Metal transporter CNNM4 · UniProt Q6P4Q7

Length
775 aa
Mass
86.6 kDa
Annotated
2026-06-09
25 papers in source corpus 16 papers cited in narrative 15 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

CNNM4 is a basolateral plasma-membrane Mg2+ efflux transporter of polarized epithelia that couples cellular magnesium homeostasis to growth, signaling, and metabolic programs (PMID:25347473, PMID:25449265). Its basolateral targeting in epithelia depends on interaction with the clathrin adaptor complexes AP-1A and AP-1B through three conserved dileucine motifs (PMID:25449265). CNNM4 stimulates Mg2+ extrusion and is functionally suppressed by binding to PRL-family phosphatases, an axis linking intracellular Mg2+ levels to AMPK/mTOR-dependent energy metabolism; loss of Cnnm4 drives malignant progression in an Apc-mutant intestinal tumor model, defining a tumor-suppressive role (PMID:25347473). Through its control of Mg2+, CNNM4 governs downstream Ca2+ signaling: it is required for TRPV1-dependent Ca2+ influx and restraint of EGFR signaling in colon epithelia (PMID:30670776), and for Ca2+ influx during sperm capacitation and hyperactivation, placing it upstream of the Ca2+-dependent tyrosine phosphorylation that licenses fertilization (PMID:27006114). CNNM4-mediated Mg2+ secretion also acts non-cell-autonomously, supporting mTORC2 activation and M2 polarization in neighboring macrophages during adipose thermogenesis (PMID:39517124), and its activity is tuned post-transcriptionally by 3'UTR-targeting microRNAs that alter intracellular Mg2+ (PMID:40862638). Biallelic missense mutations in the CNNM4 CBS-pair regulatory domain cause Jalili syndrome (cone-rod dystrophy with amelogenesis imperfecta) (PMID:19200525, PMID:19200527), with pathogenic variants acting by reducing protein and mRNA stability and Mg2+ extrusion activity rather than by mislocalization (PMID:39580587). Dysregulated CNNM4 activity further contributes to alcohol-associated liver disease via perturbed S-adenosylmethionine/PCMT1 function and mitochondrial dysfunction (PMID:39641635), and to cholangiocarcinoma progression through a NUPR1-linked ferroptosis axis (PMID:40764063).

Mechanistic history

Synthesis pass · year-by-year structured walk · 10 steps
  1. 2009 High

    Established that CNNM4, a putative metal transporter, is the causative gene for Jalili syndrome, linking CNNM4-dependent metal transport to retinal function and tooth biomineralization.

    Evidence Positional-candidate gene mapping and mutational analysis across seven families with retinal/ameloblast expression analysis

    PMID:19200525 PMID:19200527

    Open questions at the time
    • Did not define the transported ion or transport mechanism
    • Did not establish how mutations impair protein function
  2. 2014 High

    Defined CNNM4 as a Mg2+ efflux stimulator regulated by PRL phosphatase binding and tied this axis to AMPK/mTOR metabolism and tumor suppression, converting a 'putative transporter' into a defined regulatory node.

    Evidence Co-IP of CNNM4-PRL, intracellular Mg2+ assays, and Cnnm4 KO crossed into ApcΔ14/+ tumor model with rapamycin rescue

    PMID:25347473

    Open questions at the time
    • Direct transport mechanism (channel vs exchanger) not resolved
    • Structural basis of PRL inhibition not defined
  3. 2014 High

    Explained how CNNM4 reaches its functional site by showing AP-1A/AP-1B and dileucine-motif-dependent basolateral sorting in polarized epithelia.

    Evidence MDCK immunofluorescence, μ1A/μ1B siRNA knockdown, dileucine mutagenesis, and Co-IP with μ subunits

    PMID:25449265

    Open questions at the time
    • Whether the same sorting governs retinal/ameloblast localization untested
    • No structure of the AP-1/CNNM4 interface
  4. 2016 High

    Placed CNNM4 upstream of Ca2+ homeostasis in sperm capacitation, showing its loss causes near-infertility through abrogated Ca2+ influx and hyperactivation.

    Evidence Germline and germ-cell-specific Cnnm4 KO mice with sperm Ca2+ imaging, tyrosine phosphorylation blots, and forced Ca2+ entry rescue

    PMID:27006114

    Open questions at the time
    • Molecular link between Mg2+ efflux and Ca2+ channel activation unresolved
    • Identity of the Ca2+ entry pathway in sperm not defined
  5. 2019 High

    Connected CNNM4-dependent Mg2+ transport to TRPV1 Ca2+ influx and EGFR signaling in colon epithelia, mechanistically tying its loss to proliferation.

    Evidence Cnnm4 KO mice and organoids, capsaicin Ca2+ imaging, Trpv1 KO epistasis, and gefitinib rescue

    PMID:30670776

    Open questions at the time
    • How Mg2+ efflux is mechanistically coupled to TRPV1 unclear
    • Whether EGFR activation is direct or downstream of Ca2+ not separated
  6. 2024 Medium

    Showed Jalili-causing CBS-domain missense variants act by reducing mRNA/protein stability and Mg2+ extrusion rather than by mislocalization, resolving the molecular basis of pathogenicity.

    Evidence Mutant CNNM4 expression with Mg2+ efflux assays, mRNA stability assays, and localization imaging

    PMID:39580587

    Open questions at the time
    • In vivo consequences of destabilized protein not modeled
    • Does not explain tissue specificity of retinal/dental phenotypes
  7. 2024 Medium

    Revealed a non-cell-autonomous role: cold-induced CNNM4 in thermogenic adipocytes secretes Mg2+ that promotes mTORC2 activation and M2 macrophage polarization.

    Evidence Adipocyte CNNM4 overexpression/knockdown, Mg2+ efflux and mTOR binding assays, macrophage polarization, and adipose Mg-wire implantation in vivo

    PMID:39517124

    Open questions at the time
    • Direct Mg2+-mTOR DFG-motif binding rests on indirect evidence
    • Physiological range of secreted Mg2+ not quantified
  8. 2024 Medium

    Implicated CNNM4 in alcohol-associated liver disease through Mg2+-dependent control of S-adenosylmethionine/PCMT1 activity and mitochondrial function.

    Evidence GalNAc-siRNA Cnnm4 silencing in mouse ALD model with PCMT1 activity, SAM quantification, and mitochondrial assays

    PMID:39641635

    Open questions at the time
    • Mechanistic link from Mg2+ to SAM levels not fully defined
    • Causality vs correlation of mitochondrial improvement not isolated
  9. 2025 Medium

    Established post-transcriptional control of CNNM4 by multiple 3'UTR-binding microRNAs that tune intracellular Mg2+ in hepatocytes.

    Evidence High-throughput miRNA 3'UTR binding assay with miRNA overexpression and intracellular Mg2+ measurement

    PMID:40862638

    Open questions at the time
    • Physiological contexts driving these miRNAs unknown
    • In vivo relevance not tested
  10. 2026 Medium

    Linked CNNM4 to cholangiocarcinoma aggressiveness and identified a NUPR1-associated ferroptosis axis as the mechanistic pathway.

    Evidence siRNA/shRNA and GalNAc-siRNA knockdown in vitro and in vivo, CAM invasion model, proteomics, and deferiprone/ZnPP rescue

    PMID:40764063

    Open questions at the time
    • Direction of CNNM4-NUPR1 regulation not fully mechanistically resolved
    • Link between Mg2+ transport and iron/ferroptosis unclear

Open questions

Synthesis pass · forward-looking unresolved questions
  • The structural mechanism by which CNNM4 transports Mg2+, how its CBS-pair/ATP-binding module gates transport, and how Mg2+ efflux is mechanistically coupled to downstream Ca2+, EGFR, mTOR, and ferroptosis pathways remain unresolved.
  • No high-resolution structure of full-length transporter
  • ATP regulation of CBS domain unvalidated experimentally
  • Transport stoichiometry and electrogenicity unknown

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0005215 transporter activity 4 GO:0140096 catalytic activity, acting on a protein 1
Localization
GO:0005886 plasma membrane 2
Pathway
R-HSA-1643685 Disease 3 R-HSA-382551 Transport of small molecules 3 R-HSA-162582 Signal Transduction 2 R-HSA-5357801 Programmed Cell Death 1
Partners
AP-1A (Μ1A)AP-1B (Μ1B)COX11IQCB1PCMT1PRL PHOSPHATASESTRPM7TRPV1

Evidence

Reading pass · 15 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2009 CNNM4 (encoding a putative metal transporter) is the causative gene for Jalili syndrome (autosomal-recessive cone-rod dystrophy + amelogenesis imperfecta); expression confirmed in neural retina and ameloblasts of developing tooth, establishing a role for CNNM4-dependent metal transport in retinal function and tooth biomineralization. Positional-candidate gene approach; mutational analysis across seven families; expression analysis in retina and ameloblasts American journal of human genetics High 19200525 19200527
2014 CNNM4 is a membrane protein that stimulates Mg2+ efflux; it binds PRL (phosphatase of regenerating liver) family phosphatases, which suppress CNNM4-dependent Mg2+ efflux; regulation of intracellular Mg2+ by this PRL-CNNM4 axis is linked to energy metabolism and AMPK/mTOR signaling. In vivo, Cnnm4 deletion in ApcΔ14/+ mice promoted malignant progression of intestinal polyps to adenocarcinomas, demonstrating a tumor-suppressive role. Biochemical co-immunoprecipitation (CNNM4-PRL binding); intracellular Mg2+ measurements in cultured cells; Cnnm4 knockout mouse crossed with ApcΔ14/+ tumor model; mTOR inhibitor (rapamycin) rescue experiment The Journal of clinical investigation High 25347473
2014 CNNM4 localizes to the basolateral membrane of intestinal/polarized epithelia; this basolateral sorting requires interaction with clathrin adaptor protein complexes AP-1A and AP-1B via three conserved dileucine motifs in CNNM4. Simultaneous knockdown of μ1A and μ1B subunits abrogated basolateral localization. Immunofluorescence localization in MDCK cells; siRNA knockdown of AP-1A (μ1A) and AP-1B (μ1B) subunits; site-directed mutagenesis of dileucine motifs; co-immunoprecipitation of CNNM4 with μ1A and μ1B Biochemical and biophysical research communications High 25449265
2016 CNNM4 is required for Ca2+ influx during sperm capacitation; Cnnm4-deficient male mice are near-infertile due to abrogated sperm hyperactivation and perturbed Ca2+ influx. Forced Ca2+ entry into Cnnm4-deficient sperm normalized aberrant tyrosine phosphorylation, placing CNNM4 upstream of Ca2+ homeostasis in sperm capacitation. Cnnm4 germline and germ-cell-specific knockout mice; sperm motility analysis; Ca2+ imaging in live sperm; tyrosine phosphorylation western blot; forced Ca2+ entry rescue experiment Journal of cell science High 27006114
2019 CNNM4 deficiency in colon epithelia impairs capsaicin-stimulated Ca2+ influx via TRPV1, promotes cell proliferation, and constitutively activates EGF receptor signaling; gefitinib (EGFR inhibitor) rescued the proliferation phenotype, functionally linking CNNM4-dependent Mg2+ transport to Ca2+ signaling and EGFR pathway regulation in colon epithelia. Cnnm4 knockout mice; organoid Ca2+ imaging with capsaicin stimulation; immunoblotting for EGFR signaling; gefitinib pharmacological rescue; comparison with Trpv1-deficient mice Oncogene High 30670776
2005 CNNM4 (as ACDP4) physically interacts with the intracellular metal ion chaperone COX11; co-expression of ACDP4 and COX11 in HEK293 cells enhanced toxicity to copper, manganese, and cobalt ions, suggesting functional coupling in essential metal ion delivery. Yeast two-hybrid screen of human fetal brain cDNA library; ectopic expression in HEK293 cells; metal ion toxicity assays Molecular pain Medium 15840172
2011 The CBS-pair regulatory domain of human CNNM4 was successfully purified, overexpressed, and crystallized (orthorhombic space group C222), diffracting to 3.6 Å, with two molecules per asymmetric unit consistent with a CBS module dimer. Protein overexpression, purification, crystallization, and preliminary X-ray crystallographic analysis using synchrotron radiation Acta crystallographica. Section F Medium 21393841
2018 CNNM4 physically interacts with IQCB1 (a Leber congenital amaurosis gene product); a truncated CNNM4 protein (p.R605X) significantly increased apoptosis and enhanced the CNNM4-IQCB1 interaction, providing a functional link between Jalili syndrome and LCA pathways. Co-immunoprecipitation of CNNM4 and IQCB1; overexpression of truncated vs. full-length CNNM4 in cultured cells; apoptosis assay Molecular genetics and genomics : MGG Medium 29322253
2019 CNNM4 CBS domain missense variants (p.Arg407Leu and p.Thr495Ile) were predicted by molecular dynamics simulations to disrupt ATP binding at the CBS domain, causing conformational shifts in the ATP binding site, suggesting ATP-dependent regulatory mechanism for CNNM4. Molecular dynamics simulations (60 ns); docking analysis of ATP to wild-type and mutant CBS domain models Molecular genetics & genomic medicine Low 31347285
2024 CNNM4 CBS domain missense variants p.(Gly492Cys) and p.(Gly492Asp) exhibit reduced protein stability, increased mRNA decay rates, and significantly reduced Mg2+ extrusion activity compared to wild-type, despite normal subcellular localization; establishing that decreased mRNA/protein stability, not mislocalization, underlies the pathogenic mechanism. Mutant CNNM4 expression in cultured cells; Mg2+ efflux/extrusion functional assays; mRNA stability assays; subcellular localization imaging Scientific reports Medium 39580587
2024 In thermogenic adipocytes, CNNM4 expression is induced by ADRB3-PKA-CREB signaling during cold exposure, mediating Mg2+ efflux; secreted Mg2+ then binds to the DFG motif of mTOR in macrophages to facilitate mTORC2 activation and M2 polarization. CNNM4 overexpression/knockdown in adipocytes; Mg2+ efflux measurements; signaling pathway inhibition (PKA/CREB); mTOR binding assay; macrophage polarization assays; adipose-specific Mg wire implantation in vivo Advanced science Medium 39517124
2024 CNNM4 overexpression in the liver causes Mg2+ homeostasis dysregulation linked to alcohol-associated liver disease progression; silencing Cnnm4 restores PCMT1 (protein isoaspartyl methyltransferase) activity and improves mitochondrial function, with the mechanism involving CNNM4-dependent regulation of S-adenosylmethionine levels required for PCMT1 function. GalNAc-siRNA silencing of Cnnm4 in mouse ALD model; PCMT1 activity assays; mitochondrial function measurements; S-adenosylmethionine level quantification; in vitro cell studies Hepatology Medium 39641635
2025 Multiple microRNAs regulate CNNM4 expression by directly binding the 3'UTR of CNNM4 mRNA; both up- and down-regulatory miRNAs were identified, and their modulation resulted in measurable changes in intracellular Mg2+ concentration in hepatocytes. High-throughput miRNA 3'UTR binding assay; miRNA overexpression in hepatocytes; intracellular Mg2+ concentration measurement ACS chemical biology Medium 40862638
2026 CNNM4 silencing in cholangiocarcinoma cells attenuates proliferation, chemoresistance, migration, invasion, cancer stem cell properties, and Warburg effect; proteomic analysis identified nuclear protein 1 (NUPR1) as an upstream regulator of CNNM4-induced ferroptosis, with iron chelation (deferiprone) reversing the anti-proliferative effect of CNNM4 silencing. siRNA/shRNA knockdown and GalNAc-conjugated siRNA in vivo; CCA cell line functional assays; chicken chorioallantoic membrane invasion model; proteomic analysis; pharmacological rescue with deferiprone and zinc protoporphyrin IX Gut Medium 40764063
2018 CNNM4 and TRPM7 are co-expressed and co-localize in the odontoblastic process of rat odontoblasts, suggesting functional coupling of these two Mg2+ regulators in maintaining Mg2+ homeostasis in dentin formation. Single-cell RT-PCR of acutely dissociated rat odontoblasts; immunohistochemistry; immunocytochemistry co-localization analysis Archives of oral biology Low 30278312

Source papers

Stage 0 corpus · 25 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2009 Mutations in CNNM4 cause Jalili syndrome, consisting of autosomal-recessive cone-rod dystrophy and amelogenesis imperfecta. American journal of human genetics 130 19200525
2014 Membrane protein CNNM4-dependent Mg2+ efflux suppresses tumor progression. The Journal of clinical investigation 98 25347473
2009 Mutations in CNNM4 cause recessive cone-rod dystrophy with amelogenesis imperfecta. American journal of human genetics 81 19200527
2016 The Mg2+ transporter CNNM4 regulates sperm Ca2+ homeostasis and is essential for reproduction. Journal of cell science 34 27006114
2013 Dental phenotype in Jalili syndrome due to a c.1312 dupC homozygous mutation in the CNNM4 gene. PloS one 30 24194943
2005 Physical interaction and functional coupling between ACDP4 and the intracellular ion chaperone COX11, an implication of the role of ACDP4 in essential metal ion transport and homeostasis. Molecular pain 23 15840172
2019 Cnnm4 deficiency suppresses Ca2+ signaling and promotes cell proliferation in the colon epithelia. Oncogene 19 30670776
2018 Identification of a mutation in CNNM4 by whole exome sequencing in an Amish family and functional link between CNNM4 and IQCB1. Molecular genetics and genomics : MGG 15 29322253
2016 A new familial case of Jalili syndrome caused by a novel mutation in CNNM4. Ophthalmic genetics 15 27070327
2018 Molecular expression of Mg2+ regulator TRPM7 and CNNM4 in rat odontoblasts. Archives of oral biology 14 30278312
2019 A novel pathogenic missense variant in CNNM4 underlying Jalili syndrome: Insights from molecular dynamics simulations. Molecular genetics & genomic medicine 13 31347285
2018 Report of two unrelated families with Jalili syndrome and a novel nonsense heterozygous mutation in CNNM4 gene. European journal of medical genetics 13 29421602
2014 Basolateral sorting of the Mg²⁺ transporter CNNM4 requires interaction with AP-1A and AP-1B. Biochemical and biophysical research communications 11 25449265
2011 Purification, crystallization and preliminary crystallographic analysis of the CBS pair of the human metal transporter CNNM4. Acta crystallographica. Section F, Structural biology and crystallization communications 11 21393841
2024 Modulatory effects of CNNM4 on protein- l -isoaspartyl- O -methyltransferase repair function during alcohol-induced hepatic damage. Hepatology (Baltimore, Md.) 9 39641635
2020 Expanding the genotypic spectrum of Jalili syndrome: Novel CNNM4 variants and uniparental isodisomy in a north American patient cohort. American journal of medical genetics. Part A 9 32022389
2017 Novel splice site mutation in CNNM4 gene in a family with Jalili syndrome. European journal of medical genetics 9 28246031
2024 Thermogenic Adipocytes Promote M2 Macrophage Polarization through CNNM4-Mediated Mg Secretion. Advanced science (Weinheim, Baden-Wurttemberg, Germany) 6 39517124
2022 Novel homozygous nonsynonymous variant of CNNM4 gene in a Chinese family with Jalili syndrome. Molecular genetics & genomic medicine 6 35150469
2021 Cone pathway dysfunction in Jalili syndrome due to a novel familial variant of CNNM4 revealed by pupillometry and electrophysiologic investigations. Ophthalmic genetics 6 34875963
2026 Role of CNNM4 in the progression of cholangiocarcinoma: implications for ferroptosis and therapeutic potential. Gut 3 40764063
2025 A novel mutation in CNNM4 is associated with a case of Jalili syndrome in Egypt. Documenta ophthalmologica. Advances in ophthalmology 1 40232358
2024 Functional and pathogenic insights into CNNM4 variants in Jalili syndrome. Scientific reports 1 39580587
2025 microRNAs Regulate Cellular Magnesium by Tuning Expression of the Plasma Membrane Protein CNNM4. ACS chemical biology 0 40862638
2025 Novel mutation in CNNM4 gene in a Chinese family with Jalili syndrome and literature review. International journal of ophthalmology 0 41280631

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