NME3

NME3 is a nucleoside diphosphate (NDP) kinase that anchors to the mitochondrial outer membrane and executes two genetically separable activities—an oligomerization-dependent membrane-tethering function and a catalytic NDP kinase function—that together govern mitochondrial dynamics, mitophagy, and metabolic adaptation (PMID:30587587). Mitochondrial targeting and tethering depend on an N-terminal amphipathic helix that binds directly to phosphatidic acid (PA) generated by PLD6 at mitochondrial contact interfaces; PA binding together with hexamerization drives selective fusion of PLD6-remodeled mitochondria, a process enhanced by nutrient starvation (PMID:37584589). NME3 interacts with the fusion machinery MFN1/2, and while catalytic-dead NME3 can restore mitochondrial elongation, only catalytically active NME3 sustains ATP production and viability under glucose starvation (PMID:30587587). Through its membrane-binding fusion activity, NME3 also preserves nuclear genome stability, since its loss fragments mitochondria, elevates ROS, and produces nuclear DNA single-strand breaks (PMID:32708927). In mitophagy, NME3 cooperates with PLD6 to produce PA on depolarized mitochondria that repositions MFN2 near PINK1 to amplify PRKN/parkin activation (PMID:41640016), and hypoxia-induced PA enables an NME3–DRP1 interaction in which the NME3 active-site phosphohistidine protects DRP1 from MUL1-mediated ubiquitination, allowing DRP1-dependent mitophagy; knock-in mice lacking this histidine phosphorylation are vulnerable to ischemia/reperfusion injury (PMID:38480688). Beyond mitochondria, NME3 localizes to peroxisomes where its NDP kinase activity supports division (PMID:33126676), associates with Tip60–ribonucleotide reductase for recruitment to DNA damage sites in quiescent cells (PMID:26945015), localizes to the basal body with nephronophthisis proteins to support ciliary function (PMID:30111592), and positively regulates TLR5–NFκB signaling downstream of MyD88 (PMID:29523766).

1. 1995 Medium

   Established the first cellular phenotype for NME3 by showing it arrests myeloid differentiation, framing it as a regulator of cell-fate decisions before any molecular mechanism was known.

   Evidence Stable overexpression in 32Dc13 myeloid precursors with G-CSF stimulation and apoptosis readouts

   PMID:7638209

   Open questions at the time

   • No molecular activity linked to the differentiation arrest
   • Overexpression phenotype not tied to endogenous function
2. 1997 Medium

   Mapped the gene and its AP-2-driven promoter and reported a cytoplasmic GFP localization, an early and partial view of where the protein acts.

   Evidence GFP fusion microscopy in SAOS-2 cells, EMSA and CAT reporter promoter analysis

   PMID:9067290

   Open questions at the time

   • Cytoplasmic localization later refined to mitochondrial/peroxisomal compartments
   • GFP fusion may mislocalize the membrane-anchored protein
3. 2000 Medium

   Began separating catalytic from non-catalytic roles by showing catalytic and serine-61 mutants impair differentiation and disrupt NM23 hetero-multimer formation, while the anti-apoptotic effect was catalysis-independent.

   Evidence Site-directed mutagenesis, subcellular fractionation, and co-IP in neuroblastoma cells

   PMID:11042679

   Open questions at the time

   • Mechanism of the catalysis-independent anti-apoptotic effect unresolved
   • Functional consequence of hetero-multimerization not defined
4. 2012 High

   Provided in vivo genetic evidence that NDP kinase activity matters for organismal phenotype, identifying mouse Nme3 as a t-haplotype distorter acting through RHO signaling on sperm motility.

   Evidence Knockout, transgenic overexpression, enzymatic assay, and genetic epistasis in mice

   PMID:22438820

   Open questions at the time

   • RHO signaling link is genetic, not biochemically reconstituted
   • Relevance to mammalian somatic NME3 function unclear
5. 2016 Medium

   Connected NME3 to localized dNTP supply by showing it complexes with Tip60 and RNR and is recruited to DNA damage sites to support repair in quiescent cells.

   Evidence Reciprocal co-IP, site-specific recruitment assay, interaction-disrupting mutants

   PMID:26945015

   Open questions at the time

   • Direct demonstration of local dNTP synthesis at lesions not shown
   • Structural basis of Tip60 interaction unknown
6. 2018 High

   Defined NME3 as a mitochondrial outer-membrane protein with two separable functions—oligomerization-dependent fusion and NDP kinase catalysis—both required for metabolic adaptation, anchoring the modern model.

   Evidence Patient fibroblasts, domain-specific rescue mutants, live imaging, ATP and viability assays, MFN1/2 co-IP

   PMID:30587587

   Open questions at the time

   • Molecular basis of MFN1/2 interaction not structurally defined
   • How catalysis sustains ATP under starvation not fully resolved
7. 2018 Medium

   Extended NME3 function beyond mitochondria into innate immune signaling, placing it as a positive regulator of TLR5–NFκB downstream of MyD88.

   Evidence siRNA screen, knockdown/overexpression, NFκB reporter, epistasis placement

   PMID:29523766

   Open questions at the time

   • Direct molecular target in the TLR5 pathway not identified
   • Whether NDP kinase activity is required is unknown
8. 2018 Medium

   Implicated NME3 in ciliary biology by localizing it to the basal body with nephronophthisis proteins and showing knockdown causes ciliopathy phenotypes in two vertebrate models.

   Evidence Co-IP with NEK8/CEP164/ANKS6/NEK6, immunolocalization, morpholino knockdown in zebrafish and Xenopus

   PMID:30111592

   Open questions at the time

   • Molecular role at the basal body undefined
   • Direct vs indirect nature of NPHP-protein associations unclear
9. 2020 Medium

   Showed NME3 also functions at peroxisomes, where its NDP kinase activity drives division, likely by supplying GTP for DLP1, linking it to ether-lipid homeostasis.

   Evidence siRNA knockdown, catalytically-inactive mutant, patient fibroblasts, peroxisome morphology and ether-lipid measurement

   PMID:33126676

   Open questions at the time

   • Direct GTP supply to DLP1 inferred, not demonstrated biochemically
   • How NME3 partitions between mitochondria and peroxisomes unknown
10. 2020 Medium

    Causally linked NME3's mitochondrial fusion function to nuclear genome stability, showing fragmentation upon loss drives ROS-mediated nuclear DNA single-strand breaks.

    Evidence Knockdown, wild-type vs N-terminal-deletion rescue, comet assay, ROS measurement, fission inhibitor (Mdivi-1)

    PMID:32708927

    Open questions at the time

    • Mechanistic chain from ROS to specific SSB lesions not detailed
    • Relationship to the Tip60–RNR repair role unclear
11. 2023 High

    Provided the biochemical mechanism of mitochondrial tethering—direct PA binding via the N-terminal amphipathic helix plus hexamerization—and showed PLD6-dependent enrichment at contact interfaces drives selective fusion.

    Evidence PA-liposome pulldown, super-resolution live imaging, amphipathic-helix and hexamerization mutants, PLD6 depletion epistasis

    PMID:37584589

    Open questions at the time

    • Structural basis of PA-bound hexamer not solved
    • How tethering selects specific mitochondria not fully defined
12. 2024 High

    Defined NME3 as a gatekeeper for DRP1-dependent mitophagy, showing its phosphohistidine protects DRP1 from MUL1 ubiquitination, with in vivo relevance to ischemia/reperfusion injury.

    Evidence Active-site histidine knock-in mice, NME3–DRP1 co-IP, ubiquitination assays, MUL1 epistasis, ubiquitin-resistant DRP1 rescue, hypoxia mitophagy assay

    PMID:38480688

    Open questions at the time

    • How phosphohistidine biochemically blocks ubiquitination unresolved
    • Whether this protection is direct on DRP1 or via an intermediary unknown
13. 2024 Medium

    Showed NME3 is recruited under redox stress and is required for mitophagy that clears damaged mitochondria, preventing ROS accumulation, mtDNA lesions, and senescence.

    Evidence Genome-wide CRISPR screen with glutathione-depleting probe, KO validation, mitophagy/ROS/mtDNA/SASP readouts

    PMID:39133631

    Open questions at the time

    • Recruitment trigger under redox stress not molecularly defined
    • Relation to PA/PLD6 recruitment pathway not integrated
14. 2026 Medium

    Integrated NME3 into PINK1-PRKN mitophagy, showing it cooperates with PLD6 to generate PA from cardiolipin that repositions MFN2 near PINK1 to amplify parkin activation.

    Evidence Co-IP, PLA/FRET, KO cells, phospho-ubiquitin and PRKN binding assays, mito-ER tethering quantification, ubiquitin-resistant MFN2 mutants

    PMID:41640016

    Open questions at the time

    • Direct demonstration that NME3 stimulates PLD6 catalysis on cardiolipin lacking
    • Quantitative contribution relative to DRP1 pathway unclear
15. 2026 Low

    Reported a new NME3 interactor, NAA10, modulating odontogenic differentiation via RUNX2 nuclear translocation, hinting at a developmental signaling role.

    Evidence Mass spectrometry, co-localization, knockdown rescue, overexpression, RUNX2 translocation and mineralization assays

    PMID:42165278

    Open questions at the time

    • Interaction not biochemically reconstituted (co-localization plus epistasis only)
    • Mechanism linking NME3 to RUNX2 trafficking undefined
    • Single lab, single study

• How NME3 coordinates its multiple compartment-specific roles—mitochondrial fusion, mitophagy, peroxisome division, DNA repair, ciliary function, and immune signaling—through shared catalytic and membrane-binding modules remains unresolved.
• No unifying structural model of catalytic vs membrane-tethering states
• Mechanism controlling partitioning among organelles unknown
• Physiological hierarchy of the parallel mitophagy pathways undefined