Blockade of sarcolemmal TRPV2 accumulation inhibits progression of dilated cardiomyopathy.

AIMS: Dilated cardiomyopathy (DCM) is a severe disorder defined by ventricular dilation and contractile dysfunction. Abnormal Ca(2+) handling is hypothesized to play a critical pathological role in DCM progression. The transient receptor potential vanilloid 2 (TRPV2) has been previously suggested as a candidate pathway for enhanced Ca(2+) entry. Here, we examined the sarcolemmal accumulation of TRPV2 in various heart-failure model animals and DCM patients, and assessed whether presently available inhibitory tools against TRPV2 ameliorate DCM symptoms. METHODS AND
RESULTS: Immunological and cell physiological analyses revealed that TRPV2 is highly concentrated and activated in the ventricular sarcolemma of DCM patients and three animal models-δ-sarcoglycan-deficient hamsters (J2N-k), transgenic mice over-expressing sialytransferase (4C30), and doxorubicin (DOX)-induced DCM mice. Over-expression of the amino-terminal (NT) domain of TRPV2 could block the plasma membrane accumulation and influx of Ca(2+) via TRPV2. Transgenic (Tg) or adenoviral expression of the NT domain in DCM animals caused effective removal of sarcolemmal TRPV2 along with reduction in the phosphorylation of calmodulin-dependent protein kinase II (CaMKII) and reactive oxygen species (ROS) production, which were activated in DCM; further, it prevented ventricular dilation and fibrosis, ameliorated contractile dysfunction in DCM, and improved survival of the affected animals. The TRPV2 inhibitor tranilast markedly suppressed DCM progression.
CONCLUSION: Sarcolemmal TRPV2 accumulation appears to have considerable pathological impact on DCM progression, and blockade of this channel may be a promising therapeutic strategy for treating advanced heart failure.