Department of Biological Chemistry, Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel.
Channels (Austin). 2024 Dec;18(1):2341077. doi: 10.1080/19336950.2024.2341077. Epub 2024 Apr 11.
Voltage-gated calcium channels (VGCCs) are the major conduits for calcium ions (Ca) within excitable cells. Recent studies have highlighted the non-ionotropic functionality of VGCCs, revealing their capacity to activate intracellular pathways independently of ion flow. This non-ionotropic signaling mode plays a pivotal role in excitation-coupling processes, including gene transcription through excitation-transcription (ET), synaptic transmission via excitation-secretion (ES), and cardiac contraction through excitation-contraction (EC). However, it is noteworthy that these excitation-coupling processes require extracellular calcium (Ca) and Ca occupancy of the channel ion pore. Analogous to the "non-canonical" characterization of the non-ionotropic signaling exhibited by the N-methyl-D-aspartate receptor (NMDA), which requires extracellular Ca without the influx of ions, VGCC activation requires depolarization-triggered conformational change(s) concomitant with Ca binding to the open channel. Here, we discuss the contributions of VGCCs to ES, ET, and EC coupling as Ca binding macromolecules that transduces external stimuli to intracellular input prior to elevating intracellular Ca. We emphasize the recognition of calcium ion occupancy within the open ion-pore and its contribution to the excitation coupling processes that precede the influx of calcium. The non-ionotropic activation of VGCCs, triggered by the upstroke of an action potential, provides a conceptual framework to elucidate the mechanistic aspects underlying the microseconds nature of synaptic transmission, cardiac contractility, and the rapid induction of first-wave genes.
电压门控钙通道(VGCCs)是可兴奋细胞内钙离子(Ca)的主要通道。最近的研究强调了 VGCCs 的非离子型功能,揭示了它们在没有离子流动的情况下激活细胞内途径的能力。这种非离子型信号转导模式在兴奋偶联过程中起着关键作用,包括通过兴奋-转录(ET)的基因转录、通过兴奋-分泌(ES)的突触传递以及通过兴奋-收缩(EC)的心脏收缩。然而,值得注意的是,这些兴奋偶联过程需要细胞外钙(Ca)和通道离子孔的 Ca 占据。类似于 N-甲基-D-天冬氨酸受体(NMDA)表现出的非离子型信号的“非典型”特征,NMDA 不需要离子内流,但需要细胞外 Ca,VGCC 的激活需要去极化触发的构象变化(s)伴随着 Ca 结合到开放通道。在这里,我们讨论了 VGCCs 作为 Ca 结合大分子在 ES、ET 和 EC 偶联中的作用,它将外部刺激转导为细胞内输入,然后升高细胞内 Ca。我们强调了识别开放离子孔内的钙离子占据及其对钙流入之前的兴奋偶联过程的贡献。动作电位的上升触发的 VGCC 的非离子型激活,为阐明突触传递、心脏收缩和第一波基因的快速诱导的毫秒性质的机制方面提供了一个概念框架。
Channels (Austin). 2024-12
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