scholarly journals Bipolar-associated miR-499-5p controls neuroplasticity by downregulating the Cav1.2 L-type voltage gated calcium channel subunit CACNB2

2021 ◽  
Author(s):  
Helena Caria Martins ◽  
Oezge A Sungur ◽  
Carlotta Gilardi ◽  
Michael Pelzl ◽  
Silvia Bicker ◽  
...  
Keyword(s):  
Calcium Channel ◽  
Calcium Homeostasis ◽  
Childhood Maltreatment ◽  
Molecular Mechanisms ◽  
Short Term Memory ◽  
Surface Expression ◽  
Neurocognitive Dysfunction ◽  
Voltage Gated ◽  
Depressive Episodes

Bipolar disorder (BD) is a chronic mood disorder characterized by alternating manic and depressive episodes, often in conjunction with cognitive deficits. Dysregulation of neuroplasticity and calcium homeostasis as a result of complex genetic environment interactions are frequently observed in BD patients, but the underlying molecular mechanisms are largely unknown. Here, we show that a BD-associated microRNA, miR-499-5p, regulates neuronal dendrite development and cognitive function by downregulating the BD risk gene CACNB2. miR-499-5p expression is increased in peripheral blood of BD patients and healthy subjects at risk of developing the disorder due to a history of childhood maltreatment. This up-regulation is paralleled in the hippocampus of rats which underwent juvenile social isolation. Elevating miR-499-5p levels in rat hippocampal pyramidal neurons impairs dendritogenesis and reduces surface expression and activity of the voltage-gated L-type calcium channel Cav1.2. We further identified CACNB2, which encodes a regulatory β-subunit of Cav1.2, as a direct target of miR-499-5p in neurons. CACNB2 downregulation is required for the miR-499-5p dependent impairment of dendritogenesis, suggesting that CACNB2 is an important downstream target of miR-499-5p in the regulation of neuroplasticity. Finally, elevating miR-499-5p in the hippocampus in vivo is sufficient to induce short-term memory impairments in rats haploinsufficient for the Cav1.2 pore forming subunit Cacna1c. Taken together, we propose that stress-induced upregulation of miR-499-5p contributes to dendritic impairments and deregulated calcium homeostasis in BD, with specific implications for the neurocognitive dysfunction frequently observed in BD patients.

scholarly journals Caenorhabditis elegans Junctophilin has tissue-specific functions and regulates neurotransmission with extended-synaptotagmin

Genetics ◽  
2021 ◽  
Author(s):  
Christopher A Piggott ◽  
Zilu Wu ◽  
Stephen Nurrish ◽  
Suhong Xu ◽  
Joshua M Kaplan ◽  
...  
Keyword(s):  
Calcium Channels ◽  
Calcium Channel ◽  
Tissue Specific ◽  
Voltage Gated ◽  
Membrane Contact Sites ◽  
Contact Sites ◽  
Pharyngeal Muscles ◽  
Membrane Contact ◽  
Null Mutants

Abstract The junctophilin family of proteins tether together plasma membrane (PM) and endoplasmic reticulum (ER) membranes, and couple PM- and ER-localized calcium channels. Understanding in vivo functions of junctophilins is of great interest for dissecting the physiological roles of ER-PM contact sites. Here, we show that the sole C. elegans junctophilin JPH-1 localizes to discrete membrane contact sites in neurons and muscles and has important tissue-specific functions. jph-1 null mutants display slow growth and development due to weaker contraction of pharyngeal muscles, leading to reduced feeding. In the body wall muscle, JPH-1 co-localizes with the PM-localized EGL-19 voltage-gated calcium channel and ER-localized UNC-68/RyR calcium channel, and is required for animal movement. In neurons, JPH-1 co-localizes with the membrane contact site protein Extended-SYnaptoTagmin 2 (ESYT-2) in soma, and is present near presynaptic release sites. Interestingly, jph-1 and esyt-2 null mutants display mutual suppression in their response to aldicarb, suggesting that JPH-1 and ESYT-2 have antagonistic roles in neuromuscular synaptic transmission. Additionally, we find an unexpected cell non-autonomous effect of jph-1 in axon regrowth after injury. Genetic double mutant analysis suggests that jph-1 functions in overlapping pathways with two PM-localized voltage-gated calcium channels, egl-19 and unc-2, and unc-68/RyR for animal health and development. Finally, we show that jph-1 regulates the colocalization of EGL-19 and UNC-68 and that unc-68/RyR is required for JPH-1 localization to ER-PM puncta. Our data demonstrate important roles for junctophilin in cellular physiology, and also provide insights into how junctophilin functions together with other calcium channels in vivo.

scholarly journals Demonstration of reduced in vivo surface expression of activating mutant thyrotrophin receptors in thyroid sections

2002 ◽  
pp. 163-171 ◽  
Author(s):  
M Sequeira ◽  
B Jasani ◽  
D Fuhrer ◽  
M Wheeler ◽  
M Ludgate
Keyword(s):  
Molecular Mechanisms ◽  
Thyroid Tissue ◽  
Surface Expression ◽  
Germline Mutations ◽  
Antigen Retrieval ◽  
Graves Disease ◽  
Paraffin Sections ◽  
Gain Of Function

OBJECTIVE: Thyroid function and growth are controlled by TSH. Hyperthyroidism can be due to Graves' Disease (GD), in which thyroid-stimulating antibodies mimic TSH, or gain-of-function mutations in the TSH receptor (TSHR). These activating mutations have poor surface expression when assessed in non-thyroidal cells in vitro but nothing is known of their in vivo behaviour. Several TSHR antibodies have been produced but none has been applied to thyroid paraffin sections. This study aimed to develop a technique suitable for use on paraffin sections and apply it to investigate TSHR expression in thyroids harbouring activating TSHR germline mutations compared with normal and GD thyroids. DESIGN AND METHODS: Immunocytochemistry coupled with antigen retrieval, using a spectrum of antibodies to the TSHR, was applied to paraffin sections of GD thyroid tissue. Subsequently, TSHR immunoreactivity was examined in three normal thyroids, three patients with GD and three patients with familial hyperthyroidism, due to different gain-of-function TSHR germline mutations, using the optimised protocol. RESULTS: Two antibodies, A10 and T3-495, to the extracellular domain (ECD) and membrane spanning region (MSR) of the TSHR respectively, produced specific basolateral staining of thyroid follicular cells. In normal and GD thyroids, basolateral staining with T3-495 was generally more intense than with A10, suggesting a possible surfeit of MSR over ECD. Graves' Disease thyroids have more abundant TSHR than normal glands. In contrast, thyroids harbouring gain-of-function mutations have the lowest expression in vivo, mirroring in vitro findings. CONCLUSIONS: The development of an immunocytochemical method applicable to paraffin sections has demonstrated that different molecular mechanisms causing hyperthyroidism result in the lowest (mutation) and highest (autoimmunity) levels of receptor at the thyrocyte surface.

scholarly journals In vitro and in vivo phosphorylation of the Cav2.3 voltage-gated R-type calcium channel

Channels ◽  
2018 ◽  
Vol 12 (1) ◽  
pp. 326-334 ◽  
Author(s):  
T. Schneider ◽  
S. Alpdogan ◽  
J. Hescheler ◽  
F. Neumaier
Keyword(s):  
Calcium Channel ◽  
Voltage Gated

The anti-allodynic α2δ ligand pregabalin inhibits the trafficking of the calcium channel α2δ-1 subunit to presynaptic terminals in vivo

2010 ◽  
Vol 38 (2) ◽  
pp. 525-528 ◽  
Author(s):  
Claudia S. Bauer ◽  
Wahida Rahman ◽  
Alexandra Tran-Van-Minh ◽  
Rafael Lujan ◽  
Anthony H. Dickenson ◽  
...  
Keyword(s):  
Neuropathic Pain ◽  
Dorsal Root ◽  
Molecular Mechanisms ◽  
Dorsal Root Ganglion Neurons ◽  
Voltage Gated ◽  
Sensory Nervous System ◽  
Pain Symptoms ◽  
Ganglion Neurons ◽  
Peripheral Sensory

Neuropathic pain is caused by lesion or dysfunction of the peripheral sensory nervous system. Up-regulation of the voltage-gated Ca2+ channel subunit α2δ-1 in DRG (dorsal root ganglion) neurons and the spinal cord correlates with the onset of neuropathic pain symptoms such as allodynia in several animal models of neuropathic pain. The clinically important anti-allodynic drugs gabapentin and pregabalin are α2δ-1 ligands, but how these drugs alleviate neuropathic pain is poorly understood. In the present paper, we review recent advances in our understanding of their molecular mechanisms.

Carboxyl Tail Region of the Kv2.2 Subunit Mediates Novel Developmental Regulation of Channel Density

2004 ◽  
Vol 92 (6) ◽  
pp. 3446-3454 ◽  
Author(s):  
Judith T. Blaine ◽  
Alison D. Taylor ◽  
Angeles B. Ribera
Keyword(s):  
Molecular Mechanisms ◽  
Protein Domains ◽  
Functional Expression ◽  
Induced Voltage ◽  
Tail Region ◽  
Voltage Gated ◽  
Mature Neurons ◽  
Specific Regulation ◽  
Carboxyl Tail

Molecular mechanisms underlying the acquisition of stable electrical phenotypes in developing neurons remain poorly defined. As Xenopus embryonic spinal neurons mature, they initially exhibit dramatic changes in excitability due to a threefold increase in voltage-gated potassium current ( IKv) density. Later when mature neurons begin synapse formation, IKv density remains stable. Elevation of Kv1.1 and Kv2.1 RNA levels indicates that excess transcript levels of these Kv genes can increase current density in both young and mature neurons. In contrast, Kv2.2 overexpression increases IKv density in young but not mature neurons despite the presence of protein translated from injected RNA at this stage. Because protein domains can determine biophysical as well as subcellular localization properties of channel subunits, we tested whether a region of the Kv2.2 subunit regulated functional expression in mature neurons. We focused on the large cytoplasmic carboxy tail, a region that differs most between Kv2.2 and the structurally related Kv2.1 subunit. Chimeric Kv2 subunits were generated in which different regions of the large cytoplasmic carboxyl tail were exchanged between Kv2.1 and Kv2.2 subunits. All chimeric Kv2 subunits induced voltage-gated potassium currents when expressed heterologously in oocytes. In vivo chimeric subunits increased IKv density in young neurons on overexpression in the developing embryo. In contrast, in mature neurons, only those chimeras lacking a domain in the proximal carboxy terminus, proxC, increased IKv density when overexpressed. Thus the proxC domain mediates developmental and subunit-specific regulation of IKv and identifies a novel function for protein domains.

Abstract 15494: Physiological Investigation of the C57bl6 Mouse Aorta Reveals a Critical Role for Voltage Gated Calcium Channel Activity in Spontaneous Arterial Ageing

Circulation ◽  
2020 ◽  
Vol 142 (Suppl_3) ◽  
Author(s):  
Sofie De Moudt ◽  
Jhana O Hendrickx ◽  
Dorien G De Munck ◽  
Arthur J Leloup ◽  
Wim Martinet ◽  
...  
Keyword(s):  
Calcium Channel ◽  
Ex Vivo ◽  
Arterial Compliance ◽  
Critical Role ◽  
Aortic Pulse Wave Velocity ◽  
Physiological Ageing ◽  
Voltage Gated ◽  
Voltage Gated Calcium Channel ◽  
Set Up

Introduction: Arterial stiffness (AS) has gained much recognition as a hallmark and independent predictor of cardiovascular (CV) events. Although generally assumed to be an adaptive response to increased blood pressure (BP), AS precedes hypertension in at least two experimental mouse models, thus revealing an incomplete understanding of AS pathophysiology. Methods: The current study presents the longitudinal CV characterization of spontaneously ageing C57Bl6 mice (2, 4, 6, 9, 12 and 24-month old) (male, n>8). In vivo analysis of peripheral BP (Coda), aortic pulse wave velocity (aPWV, Vevo2100), and echocardiography (Vevo2100) was combined with ex vivo aortic studies of isometric reactivity (organ baths) and AS measurements in the Rodent Oscillatory Tension set-up for Arterial Compliance (ROTSAC). (Data are presented as mean ± SEM.) Results: In vivo and ex vivo characterisation confirms that aortic stiffness precedes peripheral BP alterations in spontaneously ageing C57Bl6 mice, with significantly and gradually increasing aPWV (Fig.A) and isobaric Peterson modulus (Ep) (Fig.B) from 6-month of age onward. Thereafter, cardiac hypertrophy was observed at 9-months of age (Fig.C), and peripheral BP measurement reveals elevated pulse pressure at 24-months (30% increase vs. all other ages) (Fig.D). Ex vivo investigation of the thoracic aorta shows increased contractions to phenylephrine (PE) in old (6-24 month) vs. young (2-4 month) mice (Fig.E,F) with an increased contribution of voltage-gated calcium channel (VGCC) (Fig.G,H) with age. Remarkably, no differences were observed on endothelial function, meaning that all changes occur on the level of the vascular smooth muscle cell (VSMC). Conclusions: Physiological ageing of VSMC results in high PE contractions, increased VGCC activity, and the development of significant arterial stiffening by 6-months of age. AS thereby precedes the development of peripheral BP alterations by 18 months.

scholarly journals Propofol inhibits the voltage-gated sodium channel NaChBac at multiple sites

2018 ◽  
Vol 150 (9) ◽  
pp. 1317-1331 ◽  
Author(s):  
Yali Wang ◽  
Elaine Yang ◽  
Marta M. Wells ◽  
Vasyl Bondarenko ◽  
Kellie Woll ◽  
...  
Keyword(s):  
Binding Sites ◽  
Molecular Mechanisms ◽  
General Anesthetics ◽  
Computational Docking ◽  
Voltage Gated ◽  
Nav Channels ◽  
Dynamics Simulations ◽  
Voltage Sensing Domain

Voltage-gated sodium (NaV) channels are important targets of general anesthetics, including the intravenous anesthetic propofol. Electrophysiology studies on the prokaryotic NaV channel NaChBac have demonstrated that propofol promotes channel activation and accelerates activation-coupled inactivation, but the molecular mechanisms of these effects are unclear. Here, guided by computational docking and molecular dynamics simulations, we predict several propofol-binding sites in NaChBac. We then strategically place small fluorinated probes at these putative binding sites and experimentally quantify the interaction strengths with a fluorinated propofol analogue, 4-fluoropropofol. In vitro and in vivo measurements show that 4-fluoropropofol and propofol have similar effects on NaChBac function and nearly identical anesthetizing effects on tadpole mobility. Using quantitative analysis by 19F-NMR saturation transfer difference spectroscopy, we reveal strong intermolecular cross-relaxation rate constants between 4-fluoropropofol and four different regions of NaChBac, including the activation gate and selectivity filter in the pore, the voltage sensing domain, and the S4–S5 linker. Unlike volatile anesthetics, 4-fluoropropofol does not bind to the extracellular interface of the pore domain. Collectively, our results show that propofol inhibits NaChBac at multiple sites, likely with distinct modes of action. This study provides a molecular basis for understanding the net inhibitory action of propofol on NaV channels.

scholarly journals Trafficking and Function of the Voltage-Gated Sodium Channel β2 Subunit

Biomolecules ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 604 ◽  
Author(s):  
Eric Cortada ◽  
Ramon Brugada ◽  
Marcel Verges
Keyword(s):  
Sodium Channel ◽  
Electrical Coupling ◽  
Surface Expression ◽  
Current Data ◽  
Cell Surface Expression ◽  
Gene Encoding ◽  
Voltage Gated Sodium Channel ◽  
Α Subunit ◽  
Voltage Gated

The voltage-gated sodium channel is vital for cardiomyocyte function, and consists of a protein complex containing a pore-forming α subunit and two associated β subunits. A fundamental, yet unsolved, question is to define the precise function of β subunits. While their location in vivo remains unclear, large evidence shows that they regulate localization of α and the biophysical properties of the channel. The current data support that one of these subunits, β2, promotes cell surface expression of α. The main α isoform in an adult heart is NaV1.5, and mutations in SCN5A, the gene encoding NaV1.5, often lead to hereditary arrhythmias and sudden death. The association of β2 with cardiac arrhythmias has also been described, which could be due to alterations in trafficking, anchoring, and localization of NaV1.5 at the cardiomyocyte surface. Here, we will discuss research dealing with mechanisms that regulate β2 trafficking, and how β2 could be pivotal for the correct localization of NaV1.5, which influences cellular excitability and electrical coupling of the heart. Moreover, β2 may have yet to be discovered roles on cell adhesion and signaling, implying that diverse defects leading to human disease may arise due to β2 mutations.

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