{
  "abstract": "Hypertrophic cardiomyopathy (HCM) is a genetic disease often associated with sudden cardiac death and linked to Z-disc genetic variants. Alpha-actinin 2 (ACTN2) is a key Z-disc protein critical for stabilising the contractile muscle apparatus. A novel missense ACTN2 variant, M228T, was identified in 2014 in a family of 11 HCM patients. A previous in vivo study by our group showed embryonic lethality in mice with the M228T homozygous copy.1–3 However, the mechanism by which this missense variant impacts ACTN2 protein and leads to disease has not been widely investigated. In this study, we examine the functional implications of the ACTN2 M228T variant using biochemical and cellular models.The ACTN2 M228T variant was recombinantly expressed using E.coli, and the structural and thermal stability of the mutant protein was assessed. Functional implications of this variant were further assessed using induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs).Structural modelling predictions revealed that the ACTN2 M228T variant adversely impacts the binding of ACTN2 to actin. Actin-binding assays showed increased binding affinity. Thermal assays showed decreased thermal stability, and enzymatic digestion using thermolysin showed reduced structural stability. Additional assays also showed increased aggregate formation.Moreover, the functional implications of M228T variant were assessed using an iPSC-CM model with mutant cardiomyocytes showing protein degradation, destabilisation, upregulation of hypertrophy and fibrosis. Mutant cells demonstrated impairment cellular quality control and autophagy, suggesting involvement of additional mechanisms.In summary, this study provides valuable insights into the impact of M228T variant on the protein structure and function. These approaches help facilitate our understanding of disease pathways in cardiomyopathy-linked ACTN2 variants.References Noureddine M, et al. Atrial electrical alterations with intact cardiac structure and contractile function in a mouse model of an HCM-linked ACTN2 variant. J Mol Cell Cardiol Plus. 2025 May 17;12:100455. doi: 10.1016/j.jmccpl.2025.100455. PMID: 40503000; PMCID: PMC12153375. Broadway-Stringer S, et al. Insights into the role of a cardiomyopathy-causing genetic variant in ACTN2. Cells. 2023 Feb 24;12(5):721. doi: 10.3390/cells12050721. PMID: 36899856; PMCID: PMC10001372. Girolami F, et al. Novel α-actinin 2 variant associated with familial hypertrophic cardiomyopathy and juvenile atrial arrhythmias: a massively parallel sequencing study. Circ Cardiovasc Genet. 2014 Dec;7(6):741–50. doi: 10.1161/CIRCGENETICS.113.000486. Epub 2014 Aug 30. PMID: 25173926.",
  "authors": [
    {
      "affiliations": [
        "University of Birmingham, UK"
      ],
      "name": "Maya Noureddine"
    },
    {
      "affiliations": [
        "University of Birmingham, UK"
      ],
      "name": "Fiyaz Mohammed"
    },
    {
      "affiliations": [
        "Diamond Light Source, UK"
      ],
      "name": "Halina Mikolajek"
    },
    {
      "affiliations": [
        "Diamond Light Source, UK"
      ],
      "name": "Nathan Cowieson"
    },
    {
      "affiliations": [
        "University of Oxford, UK"
      ],
      "name": "Paul Robinson"
    },
    {
      "affiliations": [
        "University of Nottingham, UK"
      ],
      "name": "Siobhan Loughna"
    },
    {
      "affiliations": [
        "University of Nottingham, UK"
      ],
      "name": "Chris Denning"
    },
    {
      "affiliations": [
        "University of Birmingham, UK"
      ],
      "name": "Alexandre Slater"
    },
    {
      "affiliations": [
        "University of Birmingham, UK"
      ],
      "name": "Sophie Broadway-Stringer"
    },
    {
      "affiliations": [
        "University of Birmingham, UK",
        "University of Oxford, UK"
      ],
      "name": "Katja Gehmlich"
    }
  ],
  "title": "P14  Mechanistic insights of alpha-actinin-2 missense variant in hypertrophic cardiomyopathy",
  "uid": "741b83f9-b500-567b-b265-458717936b55"
}