β-adrenergic activation may promote myosin light chain kinase degradation through calpain in pressure overload-induced cardiac hypertrophy: β-adrenergic activation results in MLCK degradation.

Abstract

BACKGROUND:

β-adrenergic activation is able to exacerbate cardiac hypertrophy. Myosin light chain kinase (MLCK) and its phosphorylated substrate, phospho-myosin light chain 2 (p-MLC2), play vital roles in regulating cardiac hypertrophy. However, it is not yet clear whether there is a relationship between β-adrenergic activation and MLCK in the progression of cardiac hypertrophy. Therefore, we explored this relationship and the underlying mechanisms in this work.

METHODS:

Cardiac hypertrophy and cardiomyocyte hypertrophy were induced by pressure overload and isoproterenol (ISO) stimulation, respectively. Echocardiography, histological analysis, immunofluorescence and qRT-PCR were used to confirm the successful establishment of the models. A β-blocker (metoprolol) and a calpain inhibitor (calpeptin) were administered to inhibit β-adrenergic activity in rats and calpain in cardiomyocytes, respectively. The protein expression levels of MLCK, myosin light chain 2 (MLC2), p-MLC2, myosin phosphatase 2 (MYPT2), calmodulin (CaM) and calpain were measured using western blotting. A cleavage assay was performed to assess the degradation of recombinant human MLCK by recombinant human calpain.

RESULTS:

The β-blocker alleviated cardiac hypertrophy and dysfunction, increased MLCK and MLC2 phosphorylation and decreased calpain expression in pressure overload-induced cardiac hypertrophy. Additionally, the calpain inhibitor calpeptin attenuated cardiomyocyte hypertrophy, upregulated MLCK and p-MLC2 and reduced MLCK degradation in ISO-induced cardiomyocyte hypertrophy. Recombinant human calpain degraded recombinant human MLCK in vitro in concentration- and time-dependent manners, and this degradation was inhibited by the calpain inhibitor calpeptin.

CONCLUSION:

Our study suggested that β-adrenergic activation may promote the degradation of MLCK through calpain in pressure overload-induced cardiac hypertrophy.

• Authors: Shun Wang, Haixiong Wang, Xiaoling Su, Beilei Liu, Le Wang, Hui Yan, Shuai Mao, He Huang, Congxin Huang, Mian Cheng, Gang Wu
• Journal: Biomedicine & pharmacotherapy = Biomedecine & pharmacotherapie (Biomed Pharmacother) Vol. 129 Pg. 110438 (Sep 2020) ISSN: 1950-6007 [Electronic] France
• PMID: 32768940 (Publication Type: Journal Article)
• Copyright: Copyright © 2020. Published by Elsevier Masson SAS.

Chemical References

• Adrenergic beta-Agonists
• Adrenergic beta-Antagonists
• Cysteine Proteinase Inhibitors
• Myosin Light Chains
• Receptors, Adrenergic, beta
• myosin light chain 2
• Myosin-Light-Chain Kinase
• Calpain
• Cardiac Myosins

Topics

• Adrenergic beta-Agonists (pharmacology)
• Adrenergic beta-Antagonists (pharmacology)
• Animals
• Calpain (antagonists & inhibitors, metabolism)
• Cardiac Myosins (metabolism)
• Cells, Cultured
• Cysteine Proteinase Inhibitors (pharmacology)
• Disease Models, Animal
• Enzyme Stability
• Hypertrophy, Left Ventricular (drug therapy, enzymology, physiopathology)
• Male
• Myocytes, Cardiac (drug effects, enzymology)
• Myosin Light Chains (metabolism)
• Myosin-Light-Chain Kinase (metabolism)
• Phosphorylation
• Proteolysis
• Rats, Sprague-Dawley
• Receptors, Adrenergic, beta (drug effects, metabolism)
• Ventricular Function, Left (drug effects)
• Ventricular Remodeling (drug effects)