Institute of Biological Information Processing, IBI-2: Mechanobiology, Forschungszentrum Jülich, 52425, Jülich, Germany.
Cell Commun Signal. 2020 Dec 28;18(1):191. doi: 10.1186/s12964-020-00689-5.
The electromechanical function of myocardial tissue depends on the intercellular communication between cardiomyocytes (CMs) as well as their crosstalk with other cell types. Cell injury, and subsequent death trigger inflammation as in myocardial infarction (MI) resulting in myocardial remodeling. Although mechanisms underlying myocardial cell death have been studied so far, the signaling events following single cell death and spontaneous response of connected cells in the myocardial tissue is still barely understood.
Here, we investigated the effect of laser-induced single cell death on Calcium (Ca) concentrations and transport in myocardial cell clusters in vitro. Spatial and temporal changes in intracellular Ca concentrations [Ca] were studied using a fluorescent calcium indicator, Fluo-4AM. Spontaneous signaling events following cell death were studied in rat embryonic cardiomyocytes and non-myocytes using separate cell culture systems.
Cell death triggered spontaneous increase in intracellular Ca levels ([Ca]) of surrounding cells. The spread of the observed propagating Ca signal was slow and sustained in myocytes while it was rapid and transient in fibroblasts (Fbs). Further, sustained high Ca levels temporarily impaired the contractility in CMs. The cell-type specific effect of ablation was confirmed using separate cultures of CMs and Fbs. Comparing Ca propagation speed in myocytes and fibroblasts, we argue for a diffusion-driven Ca propagation in myocytes, but not in fibroblasts. Radial and sequential Ca diffusion across the CMs through cell-cell contacts and presence of Cx43-based intercellular junctions indicated a gap junction flow of Ca.
These findings illustrate the spontaneous Ca-mediated functional interplay in myocardial cell clusters upon mechanical injury and, further, the difference in Ca signaling in cardiomyocytes and fibroblasts. Video Abstract.
心肌组织的机电功能依赖于心肌细胞（CMs）之间的细胞间通讯以及它们与其他细胞类型的相互作用。细胞损伤和随后的死亡会引发炎症，如心肌梗死（MI），导致心肌重构。尽管迄今为止已经研究了心肌细胞死亡的机制，但对于单个细胞死亡后的信号事件以及心肌组织中连接细胞的自发反应仍知之甚少。
在这里，我们研究了激光诱导的单个细胞死亡对体外心肌细胞簇中钙（Ca）浓度和运输的影响。使用荧光钙指示剂 Fluo-4AM 研究细胞内 Ca 浓度[Ca]的时空变化。使用单独的细胞培养系统研究了心肌细胞和非心肌细胞中细胞死亡后自发信号事件。
细胞死亡触发了周围细胞内 Ca 水平（[Ca]）的自发增加。观察到的传播 Ca 信号的传播速度在 CMs 中较慢且持续，而在成纤维细胞（Fbs）中较快且短暂。此外，持续的高 Ca 水平暂时损害了 CMs 的收缩性。通过 CMs 和 Fbs 的单独培养证实了消融的细胞类型特异性效应。比较 CMs 和 Fbs 中 Ca 传播速度，我们认为 CMs 中 Ca 通过细胞-细胞接触径向和顺序扩散，并且存在 Cx43 基细胞间连接，表明 Ca 通过缝隙连接流动。
这些发现说明了机械损伤后心肌细胞簇中自发的 Ca 介导的功能相互作用，进一步说明了 CMs 和成纤维细胞中 Ca 信号的差异。视频摘要。
