Diversity of Ca2+ signaling in developing cardiac cells
Diversity of Ca2+ signaling in developing cardiac cells
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DOI：
10.1196/annals.1380.014
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发表时间：
2006-01-01
期刊：
影响因子：
--
通讯作者：
Morad, Martin
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文献类型：
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作者：
Janowski, Einsley;Cleemann, Lars;Morad, Martin
在胚胎和出生后的发育过程中，随着细胞分化，哺乳动物心脏经历了快速的形态变化，在超微结构水平上，与钙信号相关的蛋白质和细胞器的表达和组织发生了变化。这里讨论了位于肌浆/内质网内和可能位于核膜内的可释放钙储存库的发育和作用。对(I)新生大鼠心肌细胞、(Ii)经1%二甲基亚砜(DMSO)悬滴培养分化为心脏表型的多能P19干细胞和(Iii)小鼠胚胎心肌细胞在胚胎第9-18天分离培养的心肌细胞进行了共聚焦钙成像实验。用咖啡因靶向Ry受体，用三磷酸腺苷或组胺靶向Ry受体，或用组胺靶向磷脂酶c(PLC)抑制剂U-73122，可激活或抑制新生和“心脏”P19细胞的钙释放通道。新生细胞表现出四种可识别的表型，其中两种具有可通过Ry或IP3受体释放的特殊钙存储，两种具有这两种类型的受体，要么控制功能上独立的存储，要么具有一定程度的重叠，因此咖啡因可以耗尽可被ATP释放的存储。P19细胞表现出不同的IP3介导的钙离子储存，以及咖啡因可释放储存，这些储存在“心脏”表型中显著增加，但在“神经”表型中缺失。在小鼠胚胎细胞中可以清楚地看到钙离子储存的不同作用。发育早期(E9-10)的部分细胞在舒张期出现强度增强的钙波，并可通过Na-Ca交换器[NCx]和兴奋性钙、钠离子通道触发同步电兴奋。在发育后期(E18)，我们观察到舒张期的钙火花似乎起源于核膜，而在兴奋过程中，核区的钙信号比周围的细胞质区域更快、更强。然而，我们也发现，与胞质钙瞬变相比，细胞核钙信号较弱，并显示出余辉。我们的结论是，在胚胎发育和出生后，即T管系统成熟之前的心肌细胞和具有心脏表型的干细胞中，钙离子的储存在释放通道的药理学方面表现出相当大的多样性，并且观察到钙信号的区域差异集中在核、核和周围。我们认为，发育中的心肌细胞的兴奋和亚细胞内钙信号的因果关系不同于成年细胞，发育中的心肌细胞表现出多样性，这种多样性可能反映在发育后期的房室和起搏细胞的不同特性上。
During embryonic and postnatal development, the mammalian heart undergoes rapid morphological changes with cellular differentiation that at the ultrastructural level encompasses altered expression and organization of the proteins and organelles associated with Ca2+ signaling. Here the development and roles of the releasable Ca2+ stores located within the sarco/endoplasmic reticulum and possibly within the nuclear envelopes are addressed. Confocal Ca2+ imaging experiments were carried out on (i) neonatal rat cardiomyocytes, (ii) pluripotent P19 stem cells, differentiated to a cardiac phenotype by culturing with 1% dimethylsulfoxide (DMSO) in hanging droplets, and (iii) mouse embryonic cardiomyocytes isolated for short-time culture at embryonic day 9-18. The Ca2+ release channels in neonatal and "cardiac" P19 cell were activated versus inhibited by targeting ryanodine (Ry) receptors with caffeine versus Ry and IP3 receptors with adenosine 5'-triphosphate (ATP) or histamine versus U-73122, a phospholipase c (PLC) inhibitor. The neonatal cells displayed four recognizable phenotypes, of which two had specialized Ca2+ stores releasable via either Ry or IP3 receptors, and two had both types of receptors, either controlling functionally separate stores or with some degree of overlap, so that caffeine could deplete the stores releasable by ATP. The P19 cells showed variable presence of IP3-mediated Ca2+ stores, and caffeine releasable stores that gained prominence in the "cardiac" phenotype, but were absent in a "neuronal" phenotype. The different roles of Ca2+ stores were seen clearly in the mouse embryonic cells. Some cells from early stages of development (E 9-10) had Ca2+ waves that increased in intensity during the diastolic interval and could trigger synchronous electrical excitation (via Na-Ca exchanger [NCX] and excitatory Ca2+ and Na+ channels). At later stages of development (E 18) we observed diastolic Ca2+ sparks that appeared to originate from the nuclear envelope, while the Ca2+ signals during excitation were faster and stronger in the nuclear region than in the surrounding cytoplasmic regions. However, we also found cells where the nuclear Ca2+ signals were weaker and showed afterglow compared to the cytosolic Ca2+ transients. We conclude that the Ca2+ stores in cardiac cells during embryogenesis and postnatal development, that is, before the maturation of the t-tubular system and in stem cells with cardiac phenotype, show considerable diversity with respect to the pharmacology of the release channels and that regional differences in Ca2+ signaling are observed centered in, at, and around the nucleus. We suggest that the causal relationship excitation and subcellular Ca2+ signals in developing cardiac cells is different from that of adult cells and that the developing cardiomyocytes show a diversity that in later stages of development may be reflected in the different properties of atrial, ventricular, and pacemaker cells.