Mutant Phosphodiesterase 3A Protects From Hypertension-Induced Cardiac Damage

Area of Science:

• Cardiovascular Science
• Genetics
• Molecular Biology

Background:

• Gain-of-function mutations in Phosphodiesterase 3A (PDE3A) cause hypertension with brachydactyly (HTNB), leading to stroke.
• Paradoxically, patients with HTNB show no cardiac hypertrophy or heart failure, suggesting a protective role of PDE3A mutations in the heart.

Purpose of the Study:

• To investigate the protective mechanisms of PDE3A mutations in the heart despite their hypertensive effects.
• To explore the potential for mimicking PDE3A mutation effects for long-term cardioprotection.

Main Methods:

• Studied new HTNB patients and CRISPR-Cas9-engineered rat models.
• Utilized telemetric blood pressure, echocardiography, micro-CT, RNA-sequencing, and single-cell RNA-sequencing.
• Established and analyzed human induced pluripotent stem cell-derived cardiomyocytes using Ca2+ imaging, FRET, and biochemical assays.

Main Results:

• Identified a new PDE3A mutation in exon 13, alongside previously identified exon 4 mutations, all causing enzyme hyperactivity.
• HTNB rat models and patients showed normal left ventricles despite hypertension; mutant hearts exhibited improved contractility and adaptive Ca2+ cycling.
• RNA-sequencing revealed altered mRNA expression in mutants, affecting metabolism and protein folding.

Conclusions:

• PDE3A mutations confer protection against hypertension-induced cardiac damage, contrasting with their vascular effects.
• Mimicking PDE3A mutation effects in the heart offers potential long-term cardioprotection, distinct from short-term PDE3A inhibition therapies.
• Findings may guide the development of novel treatments for preventing hypertension-related cardiac damage.