A distinct de novo expression of Nav1.5 sodium channels in human atrial fibroblasts differentiated into myofibroblasts
A distinct de novo expression of Nav1.5 sodium channels in human atrial fibroblasts differentiated into myofibroblasts
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DOI：
10.1113/jphysiol.2012.233593
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发表时间：
2012-09-01
影响因子：
5.5
通讯作者：
Faivre, Jean Francois
中科院分区：
文献类型：
--
作者：
Chatelier, Aurelien;Mercier, Aurelie;Faivre, Jean Francois
关键是成纤维细胞在心脏生理学中发挥着重要作用。在病理条件下，当它们分化为肌成纤维细胞时，会导致心脏纤维化。这种分化状态与表达谱的变化有关，导致离子通道等蛋白质的新表达。本研究主要研究人心房成纤维细胞和肌成纤维细胞中电压门控钠通道与成纤维细胞分化相关的电生理变化。我们发现人心房成纤维细胞在肌成纤维细胞中的分化与电压门控性钠电流的从头表达有关。多种论据支持这一电流主要由NaV1.5α亚基支持，它可能产生持续性的钠进入肌成纤维细胞。我们的数据显示，NaV1.5α亚基的表达并不局限于心房内的心肌细胞。由于纤维化是心房颤动的基本机制之一，因此研究这一通路如何影响肌成纤维细胞的功能是非常有意义的。摘要成纤维细胞在心脏生理学中发挥着重要作用。它们是细胞外基质更新和产生各种旁分泌和自分泌因子的起始点。在病理条件下，成纤维细胞增殖、迁移和分化为肌成纤维细胞，导致心脏纤维化。这种分化状态与表达谱的变化有关，导致离子通道等蛋白质的新表达。本研究进一步研究了与成纤维细胞分化相关的电生理变化，重点是人心房成纤维细胞和肌成纤维细胞中电压门控钠通道的活性。用膜片钳技术观察到人心房肌成纤维细胞呈现快内向电压门控性钠电流，电流密度为13.28+/-2.88pF-1，而未分化成纤维细胞则未检测到电流。定量RT-PCR显示，在肌成纤维细胞中有大量编码NaV1.5α亚基的转录本，与成纤维细胞相比，其表达水平增加了四倍。相应地，一半的电流被1微米的河豚毒素阻断，免疫细胞化学实验表明NAV1.5蛋白的存在。总体而言，这种电流表现出与心肌细胞钠电流相似的生物物理特征，只是窗口电流在-100 mV和-20 mV之间的电位范围内被放大。由于纤维化是心房颤动的基本机制之一，因此研究这一电流如何影响肌成纤维细胞的特性是非常有意义的。此外，由于几个NaV1.5突变与心脏病理有关，本研究为成纤维细胞参与这些突变提供了一条新的途径。
Key point Fibroblasts play a major role in heart physiology. In pathological conditions, they can lead to cardiac fibrosis when they differentiate into myofibroblasts. This differentiated status is associated with changes in expression profile leading to neo-expression of proteins such as ionic channels. The present study investigates electrophysiological changes associated with fibroblast differentiation focusing on voltage-gated sodium channels in human atrial fibroblasts and myofibroblasts. We show that human atrial fibroblast differentiation in myofibroblasts is associated with de novo expression of voltage gated sodium current. Multiple arguments support that this current is predominantly supported by the Nav1.5 alpha-subunit which may generate a persistent sodium entry into myofibroblasts. Our data revealed that Nav1.5 alpha-subunit expression is not restricted to cardiac myocytes within the atrium. Since fibrosis is one of the fundamental mechanisms implicated in atrial fibrillation, it is of great interest to investigate how this channel could influence myofibroblasts function. Abstract Fibroblasts play a major role in heart physiology. They are at the origin of the extracellular matrix renewal and production of various paracrine and autocrine factors. In pathological conditions, fibroblasts proliferate, migrate and differentiate into myofibroblasts leading to cardiac fibrosis. This differentiated status is associated with changes in expression profile leading to neo-expression of proteins such as ionic channels. The present study investigates further electrophysiological changes associated with fibroblast differentiation focusing on the activity of voltage-gated sodium channels in human atrial fibroblasts and myofibroblasts. Using the patch clamp technique we show that human atrial myofibroblasts display a fast inward voltage gated sodium current with a density of 13.28 +/- 2.88 pA pF-1 whereas no current was detectable in non-differentiated fibroblasts. Quantitative RT-PCR reveals a large amount of transcripts encoding the Nav1.5 alpha-subunit with a fourfold increased expression level in myofibroblasts when compared to fibroblasts. Accordingly, half of the current was blocked by 1 mu m of tetrodotoxin and immunocytochemistry experiments reveal the presence of Nav1.5 proteins. Overall, this current exhibits similar biophysical characteristics to sodium currents found in cardiac myocytes except for the window current that is enlarged for potentials between -100 and -20 mV. Since fibrosis is one of the fundamental mechanisms implicated in atrial fibrillation, it is of great interest to investigate how this current could influence myofibroblast properties. Moreover, since several Nav1.5 mutations are related to cardiac pathologies, this study offers a new avenue on the fibroblasts involvement of these mutations.