scholarly journals Proteolytic maturation of α2δ controls the probability of synaptic vesicular release

eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
Laurent Ferron ◽  
Ivan Kadurin ◽  
Annette C Dolphin
Keyword(s):  
Calcium Channels ◽  
Inhibitory Effect ◽  
Wild Type ◽  
Voltage Gated ◽  
Synaptic Release ◽  
Voltage Gated Calcium Channels ◽  
Vesicular Release ◽  
Active Zones ◽  
Asynchronous Release

Auxiliary α2δ subunits are important proteins for trafficking of voltage-gated calcium channels (CaV) at the active zones of synapses. We have previously shown that the post-translational proteolytic cleavage of α2δ is essential for their modulatory effects on the trafficking of N-type (CaV2.2) calcium channels (Kadurin et al., 2016). We extend these results here by showing that the probability of presynaptic vesicular release is reduced when an uncleaved α2δ is expressed in rat neurons and that this inhibitory effect is reversed when cleavage of α2δ is restored. We also show that asynchronous release is influenced by the maturation of α2δ−1, highlighting the role of CaV channels in this component of vesicular release. We present additional evidence that CaV2.2 co-immunoprecipitates preferentially with cleaved wild-type α2δ. Our data indicate that the proteolytic maturation increases the association of α2δ−1 with CaV channel complex and is essential for its function on synaptic release.

scholarly journals Inhibitory Effect of Somatostatin-14 on L-Type Voltage-Gated Calcium Channels in Cultured Cone Photoreceptors Requires Intracellular Calcium

2009 ◽  
Vol 102 (3) ◽  
pp. 1801-1810 ◽  
Author(s):  
Kuihuan Jian ◽  
Rola Barhoumi ◽  
Michael L. Ko ◽  
Gladys Y.-P. Ko
Keyword(s):  
Calcium Channels ◽  
Intracellular Calcium ◽  
G Protein ◽  
Inhibitory Effect ◽  
Calcium Stores ◽  
Dependent Effect ◽  
Voltage Gated ◽  
Circadian Phase ◽  
Voltage Gated Calcium Channels ◽  
Somatostatin 14

The inhibitory effects of somatostatin have been well documented for many physiological processes. The action of somatostatin is through G-protein-coupled receptor-mediated second-messenger signaling, which in turn affects other downstream targets including ion channels. In the retina, somatostatin is released from a specific class of amacrine cells. Here we report that there was a circadian phase-dependent effect of somatostatin-14 (SS14) on the L-type voltage-gated calcium channels (L-VGCCs) in cultured chicken cone photoreceptors, and our study reveals that this process is dependent on intracellular calcium stores. Application of 500 nM SS14 for 2 h caused a decrease in L-VGCC currents only during the subjective night but not the subjective day. We then explored the cellular mechanisms underlying the circadian phase-dependent effect of SS14. The inhibitory effect of SS14 on L-VGCCs was mediated through the pertussis-toxin-sensitive G-protein-dependent somatostatin receptor 2 (sst2). Activation of sst2 by SS14 further activated downstream signaling involving phospholipase C and intracellular calcium stores. Mobilization of intracellular Ca2+ was required for somatostatin induced inhibition of photoreceptor L-VGCCs, suggesting that somatostatin plays an important role in the modulation of photoreceptor physiology.

scholarly journals Role of voltage-gated calcium channels in epilepsy

2009 ◽  
Vol 460 (2) ◽  
pp. 395-403 ◽  
Author(s):  
Gerald W. Zamponi ◽  
Philippe Lory ◽  
Edward Perez-Reyes
Keyword(s):  
Calcium Channels ◽  
Voltage Gated ◽  
Voltage Gated Calcium Channels

scholarly journals Role of L-Type Voltage-Gated Calcium Channels in Epileptiform Activity of Neurons

2021 ◽  
Vol 22 (19) ◽  
pp. 10342
Author(s):  
Denis P. Laryushkin ◽  
Sergei A. Maiorov ◽  
Valery P. Zinchenko ◽  
Sergei G. Gaidin ◽  
Artem M. Kosenkov
Keyword(s):  
Calcium Channels ◽  
Hippocampal Neurons ◽  
Epileptiform Activity ◽  
Gaba A ◽  
Voltage Gated ◽  
Voltage Gated Calcium Channels ◽  
Effective Doses ◽  
High Doses ◽  
Paroxysmal Depolarization Shift

Epileptic discharges manifest in individual neurons as abnormal membrane potential fluctuations called paroxysmal depolarization shift (PDS). PDSs can combine into clusters that are accompanied by synchronous oscillations of the intracellular Ca2+ concentration ([Ca2+]i) in neurons. Here, we investigate the contribution of L-type voltage-gated calcium channels (VGCC) to epileptiform activity induced in cultured hippocampal neurons by GABA(A)R antagonist, bicuculline. Using KCl-induced depolarization, we determined the optimal effective doses of the blockers. Dihydropyridines (nifedipine and isradipine) at concentrations ≤ 10 μM demonstrate greater selectivity than the blockers from other groups (phenylalkylamines and benzothiazepines). However, high doses of dihydropyridines evoke an irreversible increase in [Ca2+]i in neurons and astrocytes. In turn, verapamil and diltiazem selectively block L-type VGCC in the range of 1–10 μM, whereas high doses of these drugs block other types of VGCC. We show that L-type VGCC blockade decreases the half-width and amplitude of bicuculline-induced [Ca2+]i oscillations. We also observe a decrease in the number of PDSs in a cluster and cluster duration. However, the pattern of individual PDSs and the frequency of the cluster occurrence change insignificantly. Thus, our results demonstrate that L-type VGCC contributes to maintaining the required [Ca2+]i level during oscillations, which appears to determine the number of PDSs in the cluster.

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