MYOM2

MYOM2 encodes myomesin-2 (M-protein), a major structural component of the sarcomere M-band that confers mechanical elasticity and force buffering in striated muscle; patient-derived cardiomyocytes carrying MYOM2 mutations show myofibrillar disarray and reduced passive force at increasing sarcomere lengths, and loss of the Drosophila ortholog produces cardiac dilation and synergistic genetic interactions with the thick-filament gene Mhc (MYH6/7) (PMID:33033063). Proper M-band incorporation of MYOM2 depends on ALPK3, with which it colocalizes at both the M-band and the nuclear envelope; ALPK3 loss mislocalizes MYOM2 and disrupts M-band architecture (PMID:36321451). In skeletal muscle, MYOM2 is a direct binding partner within the dysferlin protein complex (PMID:23792176). Beyond its structural role, MYOM2 is a developmentally controlled node in cardiomyocyte maturation: its postnatal upregulation marks and drives a mature phenotype while suppressing cardiomyocyte proliferation and promoting binucleation (PMID:32144297, PMID:42241973). MYOM2 transcription is tightly regulated by muscle transcription factors, including activation by SIM2/ARNT1 through a non-canonical E-box (PMID:18480125), repression via MEF2C through nTRIP6-mediated recruitment of HDAC5 (PMID:27292777), and control by GATA4 (PMID:40355336). Tissue-specific functional output is reflected in layer-specific expression across muscle types that tunes thick-filament lattice order and elasticity (PMID:17325154).

1. 2007 Medium

   Established that MYOM2 content varies between muscle types and layers in a way that tunes M-band composition and mechanical properties, framing it as a determinant of muscle-specific elasticity rather than a uniform structural filler.

   Evidence qPCR, immunohistochemistry, and electron microscopy with inter-thick-filament distance quantification in extraocular versus tibialis anterior muscle

   PMID:17325154

   Open questions at the time

   • Functional elasticity/force consequences were modeled, not directly measured
   • Does not address molecular determinants of layer-specific expression
2. 2008 High

   Identified the first direct transcriptional regulator of MYOM2, showing SIM2/ARNT1 binds a non-canonical E-box in its promoter and exerts context-dependent activation versus repression.

   Evidence ChIP, promoter truncation/mutagenesis, luciferase reporter assays, and siRNA knockdown in HEK293 and human myoblasts

   PMID:18480125

   Open questions at the time

   • Mechanism behind the activator-versus-repressor switch in myoblasts not resolved
   • In vivo relevance to muscle development not tested
3. 2013 High

   Placed MYOM2 within the dysferlin protein complex by demonstrating a direct physical interaction, linking the M-band protein to membrane-repair/complex biology in skeletal muscle.

   Evidence Co-IP, blue native gel electrophoresis, and FLIM-FRET in human skeletal muscle and myotubes

   PMID:23792176

   Open questions at the time

   • Functional consequence of the dysferlin-MYOM2 interaction not defined
   • Interaction interface and stoichiometry unknown
4. 2016 High

   Defined a repressive transcriptional circuit controlling MYOM2 in proliferating myoblasts, showing nTRIP6 co-represses MEF2C and recruits HDAC5 to the MYOM2 promoter.

   Evidence Reciprocal Co-IP, ChIP at the MYOM2 promoter, and siRNA knockdown with expression readout in myoblasts

   PMID:27292777

   Open questions at the time

   • Does not address de-repression timing during differentiation
   • Direct chromatin state changes at MYOM2 not measured
5. 2020 Medium

   Demonstrated that MYOM2 marks mature cardiomyocytes and established it as a useful reporter for maturation, defining a developmental expression program rather than only a static structural role.

   Evidence Myom2-locus knock-in fluorescent reporter in mouse ESC-derived cardiomyocytes with flow cytometry, sarcomere shortening, and transcriptional profiling

   PMID:32144297

   Open questions at the time

   • Whether MYOM2 drives maturation or simply reports it not separated here
   • Laminin effect upstream of MYOM2 not mechanistically connected
6. 2020 High

   Established MYOM2 as a functionally required M-band component whose loss reduces passive sarcomere force and produces cardiomyopathy-like phenotypes across human and Drosophila systems.

   Evidence Patient-derived cardiomyocyte force measurements, Drosophila cardiac knockdown, and genetic epistasis with Mhc/MYH6/7

   PMID:33033063

   Open questions at the time

   • No structural model of how MYOM2 cross-links thick filaments
   • Human disease causality from defined MYOM2 variants not formally established as Mendelian
7. 2022 High

   Identified ALPK3 as a determinant of MYOM2 localization, showing M-band integrity and dual M-band/nuclear-envelope positioning of MYOM2 depend on ALPK3.

   Evidence Immunofluorescence colocalization plus ALPK3 loss-of-function in isogenic hiPSC-cardiomyocytes, mice, and patient tissue

   PMID:36321451

   Open questions at the time

   • Whether ALPK3 directly binds MYOM2 or acts indirectly not resolved
   • Significance of nuclear-envelope MYOM2 pool unknown
8. 2022 Medium

   Linked MYOM2 loss to diastolic dysfunction, arrhythmia, and oxidative stress in vivo, and showed exercise upregulates it, extending its role from structure to functional cardiac homeostasis.

   Evidence Drosophila tissue-specific RNAi with cardiac functional assays, oxidative stress markers, climbing, and lifespan analysis

   PMID:36554435

   Open questions at the time

   • Mechanistic link between M-band loss and oxidative stress not defined
   • Findings in fly may not transfer quantitatively to mammalian heart
9. 2023 Medium

   Connected MYOM2 protein levels to upstream contractility signaling by showing CaMKII activity regulates its expression and that CaMKII inhibition rescues drug-induced MYOM2 and rhythm changes.

   Evidence TMT proteomics, CaMKII Thr287 autophosphorylation analysis, KN-93 rescue, and rat ECG recording

   PMID:37037889

   Open questions at the time

   • Whether CaMKII acts transcriptionally or post-translationally on MYOM2 not distinguished
   • Direct CaMKII-MYOM2 relationship versus indirect not established
10. 2025 Medium

    Added GATA4 as a transcriptional regulator of MYOM2 during cardiomyocyte differentiation and showed GATA4 can rescue toxicant-induced MYOM2 loss.

    Evidence GATA4 overexpression rescue in hiPSC, with in vivo immunohistochemistry, Western blot, and qRT-PCR

    PMID:40355336

    Open questions at the time

    • Direct GATA4 binding to the MYOM2 locus not demonstrated
    • Relationship to other MYOM2 transcription factors not integrated
11. 2025 Medium

    Defined an allele- and methylation-specific cis-regulatory mechanism at rs2280906 controlling MYOM2 expression, linking it to schizophrenia risk.

    Evidence Mendelian randomization, dual-luciferase assays, gene and methylation editing, and EMSA

    PMID:41324836

    Open questions at the time

    • Tissue context for the neuropsychiatric link not clarified
    • Identity of the recruited repressive factors not fully defined
12. 2026 Medium

    Showed MYOM2 is not merely a maturation marker but actively enforces cell-cycle exit, with overexpression suppressing cardiomyocyte proliferation and driving binucleation.

    Evidence scRNA-seq pseudotime analysis plus adenoviral Myom2 overexpression with proliferation and binucleation readouts in neonatal rat cardiomyocytes

    PMID:42241973

    Open questions at the time

    • Molecular pathway linking M-band protein to cell-cycle machinery unknown
    • Whether structural assembly is required for the anti-proliferative effect not tested

• How MYOM2's structural M-band role mechanistically couples to its signaling outputs (proliferation suppression, oxidative stress protection, nuclear-envelope localization) remains unresolved.
• No structural model of MYOM2 cross-bridging within the M-band
• No molecular mechanism linking MYOM2 to cell-cycle exit
• Functional meaning of nuclear-envelope MYOM2 pool undefined