武汉云克隆科技股份有限公司

Abstract

AIMS:

Pathological cardiac hypertrophy is a major predictor for the development of cardiac diseases. It is associated with chronic neurohumoral stimulation and with altered cardiac Ca(2+) signalling in cardiomyocytes. TRPC proteins form agonist-induced cation channels, but their functional role for Ca(2+) homeostasis in cardiomyocytes during fast cytosolic Ca(2+) cycling and neurohumoral stimulation leading to hypertrophy is unknown.

METHODS AND RESULTS:

In a systematic analysis of multiple knockout mice using fluorescence imaging of electrically paced adult ventricular cardiomyocytes and Mn(2+)-quench microfluorimetry, we identified a background Ca(2+) entry (BGCE) pathway that critically depends on TRPC1/C4 proteins but not others such as TRPC3/C6. Reduction of BGCE in TRPC1/C4-deficient cardiomyocytes lowers diastolic and systolic Ca(2+) concentrations both, under basal conditions and under neurohumoral stimulation without affecting cardiac contractility measured in isolated hearts and in vivo. Neurohumoral-induced cardiac hypertrophy as well as the expression of foetal genes (ANP, BNP) and genes regulated by Ca(2+)-dependent signalling (RCAN1-4, myomaxin) was reduced in TRPC1/C4 knockout (DKO), but not in TRPC1- or TRPC4-single knockout mice. Pressure overload-induced hypertrophy and interstitial fibrosis were both ameliorated in TRPC1/C4-DKO mice, whereas they did not show alterations in other cardiovascular parameters contributing to systemic neurohumoral-induced hypertrophy such as renin secretion and blood pressure.

CONCLUSIONS:

The constitutively active TRPC1/C4-dependent BGCE fine-tunes Ca(2+) cycling in beating adult cardiomyocytes. TRPC1/C4-gene inactivation protects against development of maladaptive cardiac remodelling without altering cardiac or extracardiac functions contributing to this pathogenesis.

摘要

目的：

病理的心脏肥大是预测心脏疾病发展的主要因素。它与心肌细胞中慢性神经体液刺激和变化的心脏Ca（2+）信号有关。TRPC蛋白形成了激动剂诱导的阳离子通道，但在快速胞浆Ca（2+）循环和神经体液刺激导致细胞肥大的心肌细胞中，它们对Ca（2+）内稳态的功能作用是未知的。

方法和结果：

用了电子控制的成人心室心肌细胞和Mn（2+）-淬火微荧光法进行荧光成像从而对多基因敲除小鼠进行系统分析，我们确定了一个背景Ca（2+）入口（BGCE）通道，它很大程度上依赖于TRPC1/C4蛋白，而不是其他蛋白，如TRPC3/C6。在缺乏TRPC1/C4的心肌细胞中减少BGCE，降低了舒张和收缩的Ca（2+）浓度，在基础条件和神经体液刺激下，不影响体内和分离出的心脏的收缩功能。神经体液引起的心脏肥大以及胎儿基因（ANP，BNP）和由Ca（2+）依赖信号（(RCAN1-4，myomaxin）调控的基因表达在TRPC1/C4基因双敲除中减少了，但在TRPC1或TRPC1单基因敲除小鼠中则没有。在TRPC1/C4基因双敲除小鼠中，压力过大引起的肥大和间质纤维化都得到了改善，而它们在其他心血管参数方面却没有显示出变化，导致了系统的神经体液引起的肥大，如肾素分泌和血压。

结论：

在跳动的成人心肌细胞中，持续活性的TRPC1/C4依赖BGCE微调Ca（2+）循环。TRPC1/C4-基因失活可以在不改变心脏或心外功能的情况下防止适应不良的心脏重建。

使用试剂原文信息：Plasma angiotensinogen and AngII concentrations were determined by Angiotensinogen (JP27413, IBL, Germany) and AngII (Uscn, Life Science Inc.) ELISA assays.