The CaMKII phosphorylation site Thr1604 in the CaV1.2 channel is involved in pathological myocardial hypertrophy in rats

Yan Liu,Siqi Wang,Jingyuan Li,Xuefei Sun,Jie Zhang,Fan Ding,Liying Hao,Meimi Zhao,Xi Zheng

doi:10.1080/19336950.2020.1750189

Yan Liu, Siqi Wang + Show 7 more

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https://doi.org/10.1080/19336950.2020.1750189

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Journal: Channels	Publication Date: Jan 1, 2020
Citations: 5	License type: open-access

Affiliation: China Medical University

Abstract

ABSTRACT Residue Thr1604 in the CaV1.2 channel is a Ca2+/calmodulin dependent protein kinase II (CaMKII) phosphorylation site, and its phosphorylation status maintains the basic activity of the channel. However, the role of CaV1.2 phosphorylation at Thr1604 in myocardial hypertrophy is incompletely understood. Isoproterenol (ISO) was used to induce cardiomyocyte hypertrophy, and autocamtide-2-related inhibitory peptide (AIP) was added as a treatment. Rats in a myocardial hypertrophy development model were subcutaneously injected with ISO for two or three weeks. The heart and left ventricle weights, each of which were normalized to the body weight and cross-sectional area of the myocardial cells, were used to describe the degree of hypertrophy. Protein expression levels were detected by western blotting. CaMKII-induced CaV1.2 (Thr1604) phosphorylation (p-CaV1.2) was assayed by coimmunoprecipitation. The results showed that CaMKII, HDAC, MEF2 C, and atrial natriuretic peptide (ANP) expression was increased in the ISO group and downregulated by AIP treatment in vitro. There was no difference in the expression of these proteins between the ISO 2-week group and the ISO 3-week group in vivo. CaV1.2 channel expression did not change, but p-CaV1.2 expression was increased after ISO stimulation and decreased by AIP. In the rat model, p-CaV1.2 levels and CaMKII activity were much higher in the ISO 3-week group than in the ISO 2-week group. CaMKII-induced CaV1.2 channel phosphorylation at residue Thr1604 may be one of the key features of myocardial hypertrophy and disease development.Abbreviations: CaMKII: Ca2+/calmodulin dependent protein kinase II; p-CaMKII: autophosphorylated Ca2+/calmodulin dependent protein kinase II; CaM: calmodulin; AIP: autocamtide-2-related inhibitory peptide; ECC: excitation-contraction coupling; ISO: isoproterenol; BW: body weight; HW: heart weight; LVW: left ventricle weight; HDAC: histone deacetylase; p-HDAC: phosphorylated histone deacetylase; MEF2C: myocyte-specific enhancer factor 2C; ANP: atrial natriuretic peptide; PKC: protein kinase C

Highlights

The CaV1.2 channel is the primary source of Ca2 + influx, which initiates cardiac excitationcontraction coupling (ECC) [1,2]
The results showed that calmodulin dependent protein kinase II (CaMKII), histone deacetylase (HDAC), myocyte-specific enhancer factor 2 C (MEF2) C, and atrial natriuretic peptide (ANP) expression was increased in the ISO group and downregulated by autocamtide-2-related inhibitory peptide (AIP) treatment in vitro
Our data contribute to an increased understanding of regulatory mechanism of CaMKII and the CaV1.2 channel on cardiac hypertrophy in three key areas

Summary

Introduction

The CaV1.2 channel is the primary source of Ca2 + influx, which initiates cardiac excitationcontraction coupling (ECC) [1,2]. In addition to regulating cardiomyocyte contraction, Ca2+ influx from the CaV1.2 channel is involved in intracellular signaling and the gene regulatory events that underlie cardiac hypertrophy and disease [3,4]. CaV1.2 is modified posttranslationally (e.g. phosphorylation) and forms a macromolecular complex [9] by binding many regulatory and helper proteins that regulate its function and expression. These interactions and posttranslational modifications may be important in acquired arrhythmias, such as those that occur in the context of hypertrophy and heart failure [10,11]. CaMKII has become known as a key regulator of CaV1.2 through its phosphorylation of CaV 1.2 at its C-terminus [12]

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