Matrix Metalloproteinases Repress Hypertrophic Growth in Cardiac Myocytes.

Area of Science:

• Cardiology
• Molecular Biology
• Biochemistry

Background:

• Matrix metalloproteinases (MMPs) are known extracellular matrix modulators in heart failure.
• Emerging evidence suggests intracellular roles and varied effects (pro- and anti-hypertrophic) of MMPs in the heart.
• Different MMP sources in cardiac tissue may explain these diverse effects.

Purpose of the Study:

• To investigate the role of matrix metalloproteinases (MMPs) in the hypertrophic growth of isolated rat ventricular cardiac myocytes.
• To determine if MMPs influence cardiac myocyte size and protein synthesis.

Main Methods:

• Isolated rat ventricular cardiomyocytes were used for experiments.
• Gene expression (RT-qPCR), protein levels (western blots), and enzyme activity (zymography) of MMPs were analyzed.
• Hypertrophic growth was assessed by measuring cardiomyocyte cross-sectional area and protein synthesis rate.

Main Results:

• MMP-1, MMP-2, MMP-3, MMP-9, and MMP-14 mRNAs were detected in cardiomyocytes; protein expression of MMP-2, MMP-9, and MMP-14 was confirmed.
• Hypertrophic stimulation led to decreased MMP expression, suggesting MMP downregulation promotes hypertrophy.
• Inhibition of MMPs (using TAPI-0, TIMP2, or ARP-100) enhanced hypertrophic growth.
• TAPI-0 treatment activated ERK and Akt signaling pathways and inhibited GSK3β, which were crucial for the observed hypertrophic growth.

Conclusions:

• Inhibition of matrix metalloproteinases (MMPs) promotes hypertrophic growth in cardiomyocytes in vitro.
• MMPs in healthy hearts may play a crucial role in preventing cardiac hypertrophy.