Bouhrira, N. | bioRxiv Science

bioRxiv2025

Matrix Stiffening Induces Mechanical Memory and Nuclear Fragility in Cardiomyocytes via Microtubule-Lamin Coupling

BackgroundMechanical memory (MM) describes the persistent phenotypic remodeling following exposure to a transient extrinsic biomechanical cue. Short-term biomechanical stress is a feature of several etiologies of cardiomyopathy, including dysfunction of the viable myocardium following a large myocardial infarction. However, the nuclear mechanisms linking stiffness to persistent cellular remodeling remain poorly understood. MethodsWe cultured human iPSC-cardiomyocytes on a magnetorheological elastomer (MRE) with tunable stiffness (9-56 kPa) to mimic physiological and pathological myocardium. This allowed us to assess how transient increases in stiffness influence cellular responses such as nuclear structure, and DNA damage in hiPSC-cardiomyocytes. Using a combination of Immunofluorescence imaging, Western Blot and pharmacological interventions, we examined the role of microtubule detyrosination and the LINC (Linker of Nucleoskeleton and Cytoskeleton) complex in transducing mechanical signals from the cytoskeleton to the nucleus with a focus on MM induction. ResultsShort-term (6 h) stiff priming induced reversible phenotypic changes upon resoftening. However, 48 h of stiff priming triggered persistent MM, characterized by nuclear rupture, increased lamin A/C expression, DNA damage, and cytoplasmic leakage of DNA repair factors like KU80. Disruption of either a-tubulin detyrosination or the LINC complex prevented MM and nuclear damage, indicating that these elements are essential for nuclear mechanotransduction. In contrast, depletion of lamin A/C or DNA repair components accelerated stiffness-induced phenotypes and promoted MM onset within 6 hours. Finally, inhibition of a-tubulin detyrosination using ADV-TTL reversed both MM and DNA damage. ConclusionsAcceleration of MM induction by lamin knockdown suggests that hereditary laminopathies may be associated with increased cardiomyocyte vulnerability to transient mechanical stress inducing DNA damage and senescence. Conversely, the protective effects of limiting stiffness-induced -tubulin detyrosination, or nuclear mechano-transduction suggest potential cardioprotective strategies in the setting of laminopathies and/or sustained increases in extracellular matrix stiffness.

cell biology↗

bioRxiv2025

Cardiac fibroblasts counterbalance cardiomyocytes in LMNA cardiomyopathy pathogenesis

Genetic cardiomyopathies arising from mutations in the LMNA gene, encoding nuclear intermediate filaments lamin A/C, display variable age of onset, severity, and fibrosis development. This variability suggests a fundamental element in disease pathogenesis that has yet to be elucidated. Given the central role cardiac fibroblasts play in fibrosis, we explored the relevance of lamin A/C in cardiac fibroblast function, as very little is known in this regard. Using primary cardiac fibroblasts and in vivo mouse models, we show that Lmna mutations impact various aspects of cardiac fibroblast function in response to myocyte damage. We show that both lamin A/C depletion and point-mutant variant expression impair cardiac fibroblast proliferation and contraction whereas other functions such as cell migration appears to be mutation dependent. In vivo depletion of lamin A/C simultaneously in cardiomyocytes and cardiac fibroblasts significantly delayed disease progression, improved cardiac function, and prolonged survival, indicating that lamin A/C mediate an opposing balance between cardiomyocytes and cardiac fibroblasts in driving disease pathogenesis. Our results elucidate previously unexplored roles of lamin A/C in cardiac fibroblasts and suggest that interactions between cardiac fibroblasts and cardiomyocytes are important determinants of the rate of progression and the severity of LMNA cardiomyopathy.

cell biology↗