Phosphatidylinositol 4-Kinase IIIβ: A Therapeutic Target for Contractile Dysfunction in Hypertrophic Cardiomyocytes

Area of Science:

• Cardiology
• Molecular Biology
• Metabolic Research

Background:

• Cardiac hypertrophy is a major risk factor for heart failure, characterized by impaired heart muscle function.
• The molecular mechanisms driving hypertrophic growth and associated contractile dysfunction are not fully understood.
• A metabolic shift towards increased glucose uptake is implicated in cardiac hypertrophy progression.

Purpose of the Study:

• To investigate if inhibiting phosphatidylinositol 4-kinase IIIβ (PI4KIIIβ) can reverse enhanced glucose uptake in hypertrophic cardiomyocytes.
• To determine if PI4KIIIβ inhibition ameliorates cardiac hypertrophy-induced contractile dysfunction.
• To assess the impact of PI4KIIIβ inhibition on hypertrophic signaling, cell size, and protein synthesis.

Main Methods:

• Cardiac hypertrophy was induced in rat and human cardiomyocytes using phenylephrine (PE) or protein kinase D1 (PKD1) overexpression.
• The specific PI4KIIIβ inhibitor MI14 was used to treat hypertrophic cells.
• Measurements included mRNA expression (BNP), hypertrophic signaling, cell morphology, protein synthesis, glucose uptake, and contractile function.

Main Results:

• PE-induced hypertrophy increased BNP expression, hypertrophic signaling, cell size, protein synthesis, glucose uptake, and impaired contractile function.
• MI14 treatment prevented and reversed PE-stimulated glucose uptake and contractile dysfunction.
• PI4KIIIβ inhibition did not affect hypertrophic signaling, cell size, or protein synthesis.
• Similar effects on glucose uptake were observed in the PKD1 overexpression model.

Conclusions:

• Targeting myocardial substrate metabolism via the PI4KIIIβ pathway offers a novel strategy to treat cardiac hypertrophy-induced contractile dysfunction.
• Inhibition of PI4KIIIβ effectively reduces enhanced glucose uptake in hypertrophic cardiomyocytes.
• This approach addresses functional deficits without altering the hypertrophic growth itself, presenting a distinct therapeutic avenue.