Defective regulation of the ryanodine receptor induces hypertrophy in cardiomyocytes

Recent studies on cardiac hypertrophy animal model suggest that inter-domain interactions within the ryanodine receptor (RyR2) become defective concomitant with the development of hypertrophy (e.g. de-stabilization of the interaction between N-terminal and central domains of RyR2; T. Oda, M. Yano, T. Yamamoto, T. Tokuhisa, S. Okuda, M. Doi, T. Ohkusa, Y. Ikeda, S. Kobayashi, N. Ikemoto, M. Matsuzaki, Defective regulation of inter-domain interactions within the ryanodine receptor plays a key role in the pathogenesis of heart failure, Circulation 111 (2005) 3400-3410). To determine if de-stabilization of the inter-domain interaction in fact causes hypertrophy, we introduced DPc10 (a peptide corresponding to the G²⁴⁶⁰-P²⁴⁹⁵ region of RyR2, which is known to de-stabilize the N-terminal/central domain interaction) into rat neonatal cardiomyocytes by mediation of peptide carrier BioPORTER. After incubation for 24 h the peptide induced hypertrophy, as evidenced by significant increase in cell size and [³H]leucine uptake. K201 or dantrolene, the reagents known to correct the de-stabilized inter-domain interaction to a normal mode, prevented the DPc10-induced hypertrophy. These results suggest that disruption of the normal N-terminal/central inter-domain interaction within the RyR2 is a causative mechanism of cardiomyocyte hypertrophy.