Presynaptic Calcium Channels

Publication date: Available online 6 January 2018
Source:Neuroscience Research
Author(s): Sumiko Mochida
At the presynaptic terminal, neuronal firing activity induces membrane depolarization and subsequent Ca²⁺ entry through voltage-gated Ca²⁺ (CaV) channels triggers neurotransmitter release from the active zone. Presynaptic Ca²⁺ channels form a large signaling complex, which targets synaptic vesicles to Ca²⁺ channels for efficient release and mediates Ca²⁺ channel regulation. The presynaptic CaV2 channel family (comprising CaV2.1, CaV2.2 and CaV2.3 isoforms) encode the pore-forming α1 subunit. The cytoplasmic regions are the target of regulatory proteins for channel modulation. Modulation of presynaptic Ca²⁺ channels has a powerful influence on synaptic transmission. This article overviews spatial and temporal regulation of Ca²⁺ channels by effectors and sensors of Ca²⁺ signaling, and describes the emerging evidence for a critical role of Ca²⁺ channel regulation in control of synaptic transmission and presynaptic plasticity. Sympathetic superior cervical ganglion neurons in culture expressing CaV2.2 channels represent a well-characterized system for investigating synaptic transmission. The exogenously expressed α1 subunit of the CaV2.1 as well as endogenous CaV2.2 was examined for modulation of channel activity, and thereby regulation of synaptic transmission. The constitutive and Ca²⁺-dependent modulation of CaV2.1 channels coordinately act as spatial and temporal molecular switches to control synaptic efficacy.



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