EMC10

EMC10 is expressed as two functionally distinct isoforms — a membrane-bound form (mEMC10) and a secreted form (scEMC10) — that exert opposing control over endoplasmic reticulum homeostasis and metabolic and ion-transport signaling (PMID:36077468, PMID:38599383). mEMC10 supports cellular homeostasis: it suppresses the PERK–eIF2α–ATF4 ER-stress pathway in liver, where mEMC10 overexpression ameliorates hepatic steatosis while scEMC10 promotes ER stress (PMID:38599383), and it sustains spermatozoa Na+/HCO3− balance by positively regulating the Na/K-ATPase β3 subunit ATP1B3, an mEMC10–Na,K-ATPase α4β3 axis required for sperm motility, cAMP/PKA-dependent phosphorylation, capacitation, and the acrosome reaction (PMID:29659949, PMID:36077468). scEMC10 acts as a circulating inhibitor of metabolic signaling: it is internalized and binds the catalytic subunit of PKA to suppress PKA–CREB activity and thermogenesis in adipocytes (PMID:36443308), and it suppresses muscle glucose uptake by inhibiting GLUT4 expression and membrane translocation through dampened AMPK and insulin signaling (PMID:40441535). In the brain, Emc10 up-regulation driven by 22q11.2-associated microRNA dysregulation is a causal driver of schizophrenia-related synaptic plasticity and behavioral deficits, as Emc10 loss-of-function rescues these phenotypes in the 22q11.2 deletion model (PMID:28696314). In the infarcted heart, bone marrow-derived monocyte/macrophage Emc10 promotes angiogenesis and endothelial cell migration via small GTPases, PAK, and p38 MAPK–MK2-dependent actin polymerization (PMID:28931551).

1. 2009 Low

   Established that EMC10 (INM02) is a glucose-responsive gene whose expression and protein secretion are induced by high glucose, first hinting at a secreted, metabolically regulated product.

   Evidence RT-qPCR and ELISA in MIN6 cells and isolated islets under varying glucose, with serum detection

   PMID:19570817

   Open questions at the time

   • No mechanistic pathway placed beyond glucose regulation
   • Did not distinguish isoforms or identify a molecular target
   • Secreted form's physiological action unknown
2. 2017 Medium

   Defined a bone marrow–heart axis in which monocyte/macrophage-derived Emc10 drives post-infarction angiogenesis, answering where Emc10 acts and through which intracellular signaling it promotes endothelial migration.

   Evidence Emc10-KO and bone marrow chimeric mice with coronary artery ligation, endothelial migration and actin polymerization assays, infarct explant outgrowth

   PMID:28931551

   Open questions at the time

   • Receptor or surface mediator linking Emc10 to small GTPase/PAK activation not identified
   • Whether the secreted isoform is the active species in this context not resolved
   • Human relevance untested
3. 2017 High

   Placed Emc10 up-regulation as a causal node downstream of 22q11.2 microRNA dysregulation in schizophrenia-related circuit and behavioral deficits, establishing it as a disease-relevant effector.

   Evidence Genetic epistasis in Df(16)A+/− mice with Mirta22 LoF allele, behavioral and electrophysiological/structural plasticity readouts

   PMID:28696314

   Open questions at the time

   • Molecular mechanism by which neuronal Emc10 inhibits maturation not defined
   • Isoform responsible in neurons unknown
   • Downstream synaptic effectors not identified
4. 2018 High

   Connected EMC10 to ion homeostasis by showing its loss inactivates sperm Na/K-ATPase, raising intracellular Na+ and disrupting the HCO3−/cAMP/PKA/tyrosine-phosphorylation cascade required for fertility.

   Evidence Emc10 KO mice with ion measurements, PKA substrate and tyrosine phosphorylation assays, ICSI rescue

   PMID:29659949

   Open questions at the time

   • Direct molecular interaction with the Na/K-ATPase not demonstrated
   • Whether EMC10 regulates pump expression or activity unresolved at this stage
   • Isoform contribution not yet dissected
5. 2022 Medium

   Resolved that the membrane-bound isoform specifically maintains sperm ion balance by up-regulating the Na/K-ATPase β3 subunit ATP1B3, separating mEMC10 function from the secreted form.

   Evidence Isoform-specific intra-testis overexpression and recombinant scEMC10 treatment in Emc10 KO mice, ATP1B3 quantification, motility assays

   PMID:36077468

   Open questions at the time

   • Mechanism by which mEMC10 regulates ATP1B3 expression unknown
   • Direct binding to the pump not shown
   • Single-lab isoform rescue
6. 2022 Medium

   Identified scEMC10 as a circulating PKA inhibitor that is internalized and binds the PKA catalytic subunit to suppress CREB activity and adipocyte thermogenesis, giving the secreted isoform a defined molecular target.

   Evidence Co-IP/binding assay, Emc10 KO and scEMC10-overexpressing mice, energy expenditure and CREB assays, neutralizing antibody

   PMID:36443308

   Open questions at the time

   • Mechanism of scEMC10 cellular uptake not defined
   • Structural basis of PKA binding unknown
   • Reciprocal/structural validation of interaction limited
7. 2024 Medium

   Demonstrated the two isoforms have opposing effects on hepatic ER stress, with mEMC10 suppressing and scEMC10 promoting PERK–eIF2α–ATF4 signaling, unifying the isoform dichotomy in a metabolic disease context.

   Evidence Isoform-specific KO and hepatic overexpression mice, scEMC10 neutralizing antibody, MCD/tunicamycin models, pathway analysis in HepG2

   PMID:38599383

   Open questions at the time

   • How mEMC10 mechanistically restrains PERK signaling not defined
   • Receptor mediating scEMC10's pro-ER-stress effect unknown
   • Single-lab models
8. 2025 Medium

   Extended scEMC10's inhibitory metabolic role to skeletal muscle, showing it suppresses GLUT4 expression/translocation and AMPK/insulin signaling, positioning circulating scEMC10 as a regulator of whole-body glucose homeostasis.

   Evidence Emc10 KO mice, recombinant scEMC10 and neutralizing antibody, myoblast studies, GLUT4 translocation and AMPK assays, glucose uptake measurements

   PMID:40441535

   Open questions at the time

   • Surface receptor for scEMC10 in muscle not identified
   • Whether PKA binding underlies the AMPK/insulin effects not connected
   • Single-lab study

• The cell-surface receptor(s) or uptake machinery through which secreted scEMC10 acts across tissues, and the molecular basis by which mEMC10 supports ER and ion-pump homeostasis, remain unresolved.
• No receptor identified for scEMC10 internalization
• No structural model of EMC10 or its complexes
• Mechanism linking mEMC10 to ATP1B3 and PERK pathway regulation undefined