Department of Pharmaceutical Toxicology, School of Pharmacy, China Medical University, Shenyang, China.
Channels (Austin). 2020 Dec;14(1):151-162. doi: 10.1080/19336950.2020.1750189.
Residue Thr1604 in the Ca1.2 channel is a Ca/calmodulin dependent protein kinase II (CaMKII) phosphorylation site, and its phosphorylation status maintains the basic activity of the channel. However, the role of Ca1.2 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 Ca1.2 (Thr1604) phosphorylation (p-Ca1.2) 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 . There was no difference in the expression of these proteins between the ISO 2-week group and the ISO 3-week group . Ca1.2 channel expression did not change, but p-Ca1.2 expression was increased after ISO stimulation and decreased by AIP. In the rat model, p-Ca1.2 levels and CaMKII activity were much higher in the ISO 3-week group than in the ISO 2-week group. CaMKII-induced Ca1.2 channel phosphorylation at residue Thr1604 may be one of the key features of myocardial hypertrophy and disease development. 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.
钙通道 1.2 型（Ca1.2）上的残基 Thr1604 是钙/钙调蛋白依赖性蛋白激酶 II（CaMKII）的磷酸化位点，其磷酸化状态维持着通道的基本活性。然而，Ca1.2 上 Thr1604 的磷酸化在心肌肥厚中的作用尚不完全清楚。异丙肾上腺素（ISO）用于诱导心肌细胞肥大，并用自催化肽-2 相关抑制肽（AIP）作为治疗药物。心肌肥厚发展模型中的大鼠通过皮下注射 ISO 持续两周或三周。心脏和左心室重量，分别用体重和心肌细胞的横截面积进行标准化，用于描述肥大程度。通过 Western blot 检测蛋白表达水平。通过共免疫沉淀检测 CaMKII 诱导的 Ca1.2（Thr1604）磷酸化（p-Ca1.2）。结果显示，ISO 组中 CaMKII、HDAC、MEF2C 和心钠肽（ANP）的表达增加，AIP 处理后下调。ISO 2 周组和 ISO 3 周组之间这些蛋白的表达没有差异。Ca1.2 通道表达没有变化，但 ISO 刺激后 p-Ca1.2 表达增加，AIP 处理后减少。在大鼠模型中，ISO 3 周组的 p-Ca1.2 水平和 CaMKII 活性明显高于 ISO 2 周组。CaMKII 诱导的 Ca1.2 通道残基 Thr1604 磷酸化可能是心肌肥厚和疾病发展的关键特征之一。CaMKII：钙/钙调蛋白依赖性蛋白激酶 II；p-CaMKII：自磷酸化的钙/钙调蛋白依赖性蛋白激酶 II；CaM：钙调蛋白；AIP：自催化肽-2 相关抑制肽；ECC：兴奋-收缩偶联；ISO：异丙肾上腺素；BW：体重；HW：心脏重量；LVW：左心室重量；HDAC：组蛋白去乙酰化酶；p-HDAC：磷酸化组蛋白去乙酰化酶；MEF2C：肌细胞特异性增强因子 2C；ANP：心钠肽；PKC：蛋白激酶 C。
