Annette Dolphin

Voltage-sensitive calcium channels (VSCCs) influence bone structure and function, including anabolic responses to mechanical loading. While the pore-forming (α1 ) subunit of VSCCs allows Ca2+ influx, auxiliary subunits regulate the biophysical properties of the pore. The α2 δ1 subunit influences gating kinetics of the α1 pore and enables mechanically induced signaling in osteocytes; however, the skeletal function of α2 δ1 in vivo remains unknown. In this work, we examined the skeletal consequences of deleting Cacna2d1 , the gene encoding α2 δ1 ...

N-type calcium channels (CaV 2.2) are predominantly localized in presynaptic terminals, and are particularly important for pain transmission in the spinal cord. Furthermore, they have multiple isoforms, conferred by alternatively spliced or cassette exons, which are differentially expressed. Here, we have examined alternatively spliced exon47 variants that encode a long or short C-terminus in human CaV 2.2. In the Ensembl database, all short exon47-containing transcripts were associated with the absence of exon18a, therefore, we also examined the effect of inclusion or absence of exon18a, combinatorially with the exon47 splice variants...

Dorsal and ventral medial entorhinal cortex (mEC) regions have distinct neural network firing patterns to differentially support functions such as spatial memory. Accordingly, mEC layer II dorsal stellate neurons are less excitable than ventral neurons. This is partly because the densities of inhibitory conductances are higher in dorsal than ventral neurons. Here, we report that T-type Ca2+ currents increase 3-fold along the dorsal-ventral axis in mEC layer II stellate neurons, with twice as much CaV 3.2 mRNA in ventral mEC compared with dorsal mEC...

Mueller et al. [1] uncover distinct roles for CaV 1 and CaV 2 channels in neurotransmitter release at the C. elegans neuromuscular junction. Although nanodomain coupling occurs via clustered CaV 2 channels, evidence is also presented that release of a separate vesicular pool is mediated by more peripheral, dispersed CaV 1 channels, requiring obligatory coupling with RYR to amplify the Ca2+ signal.

In this hybrid review, we have first collected and reviewed available information on the structure and function of the enigmatic cache domains in α2 δ proteins. These are organized into two double cache (dCache_1) domains, and they are present in all α2 δ proteins. We have also included new data on the key function of these domains with respect to amino acid and gabapentinoid binding to the universal amino acid-binding pocket, which is present in α2 δ-1 and α2 δ-2...

The N-type calcium channel, CaV 2.2 is key to neurotransmission from the primary afferent terminals of dorsal root ganglion (DRG) neurons to their postsynaptic targets in the spinal cord. In this study, we have utilized CaV 2.2_HA knock-in mice, because the exofacial epitope tag in CaV 2.2_HA enables accurate detection and localization of endogenous CaV 2.2. CaV 2.2_HA knock-in mice were used as a source of DRGs to exclusively study the presynaptic expression of N-type calcium channels in co-cultures between DRG neurons and wild-type spinal cord neurons...

Neuronal N-type (Ca V 2.2) voltage-gated calcium channels are essential for neurotransmission from primary afferent terminals in the dorsal horn. In this study, we have used a knockin mouse containing Ca V 2.2 with an inserted extracellular hemagglutinin tag (Ca V 2.2_HA), to visualise the pattern of expression of endogenous Ca V 2.2 in dorsal root ganglion (DRG) neurons and their primary afferents in the dorsal horn. We examined the effect of partial sciatic nerve ligation (PSNL) and found an increase in Ca V 2...

KEY POINTS: We have examined the roles of CaV 2.2 channels and α2 δ-1 in homeostatic synaptic plasticity in hippocampal neurons in culture. We find that chronic silencing of neuronal activity resulted in elevated presynaptic Ca2+ transients, mediated by increased levels of CaV 2.2 channels at presynaptic sites. We further find that the level of endogenous α2 δ-1 decreased during homeostatic synaptic plasticity, whereas overexpression of α2 δ-1 prevented homeostatic synaptic plasticity in hippocampal neurons...

The auxiliary α2 δ subunits of voltage-gated calcium (CaV ) channels are key to augmenting expression and function of CaV 1 and CaV 2 channels, and are also important drug targets in several therapeutic areas, including neuropathic pain. The α2 δ proteins are translated as preproteins encoding both α2 and δ, and post-translationally proteolyzed into α2 and δ subunits, which remain associated as a complex. In this study, we have identified ADAM17 as a key protease involved in proteolytic processing of pro-α2 δ-1 and α2 δ-3 subunits...

The publication of papers containing data obtained with suboptimal rigor in the experimental design and choice of key reagents, such as antibodies, can result in a lack of reproducibility and generate controversy that can both needlessly divert resources and, in some cases, damage public perception of the scientific enterprise. This exemplary paper by Buonarati et al. (2018)1 shows how a previously published, potentially important paper on calcium channel regulation falls short of the necessary mark, and aims to resolve the resulting controversy...

N-type voltage-gated calcium channels (CaV 2.2) are predominantly expressed at presynaptic terminals, and their function is regulated by auxiliary α2 δ and β subunits. All four mammalian α2 δ subunits enhance calcium currents through CaV 1 and CaV 2 channels, and this increase is attributed, in part, to increased CaV expression at the plasma membrane. In the present study we provide evidence that α2 δ-1, like α2 δ-2, is recycled to the plasma membrane through a Rab11a-dependent endosomal recycling pathway...

In this short review, I describe from personal experience how every step in the career of any scientist, no matter how disjointed and pragmatic each might seem at the time, will almost inevitably meld together, to help us all tackle novel projects. My postdoctoral research in Paul Greengard's lab, where I investigated neurotransmitter-mediated phosphorylation of Synapsin I, was instrumental in my career progression, and Paul's support was instrumental in my ability to make a leap into independent research.

Voltage-gated calcium channels are the principal conduits for depolarization-mediated Ca2+ entry into excitable cells. In this review, the biophysical properties of the relevant members of this family of channels, those that are present in presynaptic terminals, will be discussed in relation to their function in mediating neurotransmitter release. Voltage-gated calcium channels have properties that ensure they are specialized for particular roles, for example, differences in their activation voltage threshold, their various kinetic properties, and their voltage-dependence of inactivation...

Chemical synapses are heterogeneous junctions formed between neurons that are specialized for the conversion of electrical impulses into the exocytotic release of neurotransmitters. Voltage-gated Ca2+ channels play a pivotal role in this process as they are the major conduits for the Ca2+ ions that trigger the fusion of neurotransmitter-containing vesicles with the presynaptic membrane. Alterations in the intrinsic function of these channels and their positioning within the active zone can profoundly alter the timing and strength of synaptic output...

The fight-or-flight response is studied by all students of Physiology as a concerted bodily response to danger. Liu et al (2020) have now revealed its mechanism, after surveying the proteomic neighbourhood around the cardiac calcium channels in a study which is a tour-de-force of modern biological techniques.

Fragile X syndrome (FXS), the most common form of inherited intellectual disability and autism, results from the loss of fragile X mental retardation protein (FMRP). We have recently identified a direct interaction of FMRP with voltage-gated Ca2+ channels that modulates neurotransmitter release. In the present study we used a combination of optophysiological tools to investigate the impact of FMRP on the targeting of voltage-gated Ca2+ channels to the active zones in neuronal presynaptic terminals. We monitored Ca2+ transients at synaptic boutons of dorsal root ganglion (DRG) neurons using the genetically-encoded Ca2+ indicator GCaMP6f tagged to synaptophysin...

"Ion Channels and Neuropharmacology: From the Past to the Future" is the main theme of articles in Volume 60 of the Annual Review of Pharmacology and Toxicology . Reviews in this volume discuss a wide spectrum of therapeutically relevant ion channels and GPCRs with a particular emphasis on structural studies that elucidate drug binding sites and mechanisms of action. The regulation of ion channels by second messengers, including Ca2+ and cyclic AMP, and lipid mediators is also highly relevant to several of the ion channels discussed, including KCNQ channels, HCN channels, L-type Ca2+ channels, and AMPA receptors, as well as the aquaporin channels...

Patients with amyotrophic lateral sclerosis (ALS) often show hallmarks of type 2 diabetes mellitus (T2DM). However, the causal link between ALS and T2DM has remained a mystery. We now demonstrate that 60% of ALS patients with T2DM (ALS-T2DM) have sera that exaggerated K+ -induced increases in cytosolic free Ca2+ concentration ([Ca2+ ]i ) in mouse islet cells. The effect was attributed to the presence of pathogenic immunoglobulin Gs (IgGs) in ALS-T2DM sera. The pathogenic IgGs immunocaptured the voltage-dependent Ca2+ (CaV ) channel subunit CaV α2 δ1 in the plasma membrane enhancing CaV 1 channel-mediated Ca2+ influx and [Ca2+ ]i , resulting in impaired mitochondrial function...

Voltage-gated calcium channels are exquisitely Ca2+ selective, conferred primarily by four conserved pore-loop glutamate residues contributing to the selectivity filter. There has been little previous work directly measuring whether the trafficking of calcium channels requires their ability to bind Ca2+ in the selectivity filter or to conduct Ca2+ . Here, we examine trafficking of neuronal CaV 2.1 and 2.2 channels with mutations in their selectivity filter and find reduced trafficking to the cell surface in cell lines...

We reappraise the psychiatric potential of calcium channel blockers (CCBs). First, voltage-gated calcium channels are risk genes for several disorders. Second, use of CCBs is associated with altered psychiatric risks and outcomes. Third, research shows there is an opportunity for brain-selective CCBs, which are better suited to psychiatric indications.