Differential activation of stress-response signaling in load-induced cardiac hypertrophy and failure

Area of Science:

• Cardiovascular Biology
• Molecular Cardiology
• Heart Failure Pathophysiology

Background:

• Myocardial hypertrophy is common in heart failure, contributing to disease progression.
• Regulatory mechanisms for coexisting hypertrophy, systolic dysfunction, and diastolic stiffness remain poorly understood.
• Intracellular signaling pathways' differential activation under hemodynamic stress is hypothesized but not well-characterized.

Purpose of the Study:

• To investigate the differential activation of intracellular signaling pathways in response to graded hemodynamic stress.
• To compare compensated hypertrophy and pressure-overload heart failure phenotypes.
• To elucidate the role of calcineurin signaling in load-induced cardiac hypertrophy and failure.

Main Methods:

• Development of mouse models with graded pressure overload to simulate cardiac stress.
• Surgical interventions designed to differentiate compensated from decompensated cardiac responses.
• Analysis of intracellular signaling pathways, stress-response signaling, and calcium (Ca2+) handling.

Main Results:

• Two distinct hypertrophic phenotypes were identified with minimal differences in key intracellular signaling pathway activation.
• Calcineurin signaling was functionally required for hypertrophic growth in both compensated and decompensated models.
• Suppression of calcineurin signaling did not lead to clinical deterioration or increased mortality in either model.

Conclusions:

• Distinct hypertrophic phenotypes in heart failure exhibit similar intracellular signaling activation patterns.
• Calcineurin signaling plays a critical role in mediating hypertrophic growth but is not essential for maintaining cardiac function or survival.
• Differences in stress-response signaling and Ca2+ handling exist between compensated and decompensated states, offering potential therapeutic targets.