The heart has a dynamic compensatory mechanism for haemodynamic stress. However, the molecular details of how mechanical forces are transduced in the heart are unclear. Here we show that the transient receptor potential, vanilloid family type 2 (TRPV2) cation channel is critical for the maintenance of cardiac structure and function. Within 4 days of eliminating TRPV2 from hearts of the adult mice, cardiac function declines severely, with disorganization of the intercalated discs that support mechanical coupling with neighbouring myocytes and myocardial conduction defects. After 9 days, cell shortening and Ca2+ handling by single myocytes are impaired in TRPV2-deficient hearts. TRPV2-deficient neonatal cardiomyocytes form no intercalated discs and show no extracellular Ca2+-dependent intracellular Ca2+ increase and insulin-like growth factor (IGF-1) secretion in response to stretch stimulation. We further demonstrate that IGF-1 receptor/PI3K/Akt pathway signalling is significantly downregulated in TRPV2-deficient hearts, and that IGF-1 administration partially prevents chamber dilation and impairment in cardiac pump function in these hearts. Our results improve our understanding of the molecular processes underlying the maintenance of cardiac structure and function.

Heart failure is the major cause of death for muscular dystrophy patients, however, the molecular pathomechanism remains unknown. Here, we show the detailed molecular pathogenesis of muscular dystrophy-associated cardiomyopathy in mice lacking the fukutin gene (Fktn), the causative gene for Fukuyama muscular dystrophy. Although cardiac Fktn elimination markedly reduced α-dystroglycan glycosylation and dystrophin-glycoprotein complex proteins in sarcolemma at all developmental stages, cardiac dysfunction was observed only in later adulthood, suggesting that membrane fragility is not the sole etiology of cardiac dysfunction. During young adulthood, Fktn-deficient mice were vulnerable to pathological hypertrophic stress with downregulation of Akt and the MEF2-histone deacetylase axis. Acute Fktn elimination caused severe cardiac dysfunction and accelerated mortality with myocyte contractile dysfunction and disordered Golgi-microtubule networks, which were ameliorated with colchicine treatment. These data reveal fukutin is crucial for maintaining myocyte physiology to prevent heart failure, and thus, the results may lead to strategies for therapeutic intervention.

Induced overexpression of NCX1 attenuated pressure overload-induced pathological cardiac remodelling. Thus, maintaining NCX1 activity may be a potential therapeutic strategy for preventing the progression of HF.

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Mechanotransduction plays important roles in many sensory processes, including touch, pain, hearing, and proprioception. However, the molecular mechanisms of mechanical nociception have remained unclear. Here, we showed that elimination of transient receptor potential vanilloid 2 (TRPV2) in mice resulted in the deficit of mechanical nociception due to the lack of mechanosensitivity in a subclass of adult primary sensory neurons (PSNs). The PSN-specific TRPV2-deficient mice showed behavioural impairment of mechanical nociception in tail-pressure and von Frey hair tests, without defects in axonal growth and neuronal composition. Conversely, the mice displayed normal behaviour to noxious heat and non-noxious tactile stimuli. Furthermore, based on the stretch-evoked Ca2+ response of cultured PSNs, we characterised two types of stretch-activated neurons in normal mice; fast-decay high-threshold and slow-decay low-threshold mechanosensitive. The cultured neurons from TRPV2-deficient mice lacked stretch-evoked Ca2+ responses by fast-decay neurons normally activated by high-threshold mechanical stimulation. These results demonstrated that TRPV2 has a critical role in mechanical nociception in the adult somatosensory system.