Enhancing calmodulin binding to cardiac ryanodine receptor completely inhibits pressure-overload induced hypertrophic...

Area of Science:

• Cardiovascular Biology
• Molecular Cardiology
• Cellular Physiology

Background:

• Cardiac hypertrophy is a significant risk factor for cardiovascular disease prognosis.
• Intracellular calcium dysregulation is implicated in cardiac hypertrophy pathogenesis.
• The precise molecular mechanisms driving cardiac hypertrophy remain incompletely understood.

Purpose of the Study:

• To investigate if pressure-overload induced cardiac hypertrophy results from cardiac ryanodine receptor (RyR2) destabilization via calmodulin (CaM) dissociation and subsequent calcium (Ca2+) leakage.
• To determine if genetically enhancing CaM-RyR2 binding affinity can prevent or rescue this form of hypertrophy.

Main Methods:

• Utilized a pressure-overload model to induce cardiac hypertrophy.
• Assessed RyR2 stability, CaM dissociation, Ca2+ leakage, and reactive oxygen species (ROS) generation in the early stages of hypertrophy.
• Evaluated the effects of genetically enhancing CaM-RyR2 binding affinity on hypertrophic signaling, cardiac function, and survival.

Main Results:

• Identified ROS-mediated RyR2 destabilization and Ca2+ leakage occurring early in pressure-overload induced cardiac hypertrophy, even when contractile function is preserved.
• Observed associated relaxation dysfunction accompanying RyR2 destabilization.
• Demonstrated that stabilizing RyR2 by increasing CaM binding affinity completely inhibited hypertrophic signaling and improved survival.

Conclusions:

• RyR2 destabilization due to CaM dissociation and subsequent Ca2+ leakage is a critical early event in pressure-overload induced cardiac hypertrophy.
• Enhancing the CaM-RyR2 interaction represents a promising therapeutic target to prevent or treat cardiac hypertrophy and improve patient outcomes.