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Channel trafficking

Wen Dun, Peter Danilo, Peter J Mohler, Penelope A Boyden
Cardiac Na+ channel remodeling provides a critical substrate for generation of reentrant arrhythmias in border zones of the infarcted canine heart. Recent studies show that Nav1.5 cytoskeletal- and endosomal-based membrane trafficking and function are linked to tubulin, microtubular (MT) networks, and Eps15 homology domain containing proteins like EHD4. AIM: Our objective is to understand the relation of tubulin and EHD4 to Nav 1.5 channel protein remodeling observed in border zone cells (IZs) when arrhythmias are known to occur; that is, 3-h, 48-h and 5-day post coronary occlusion...
March 10, 2018: Life Sciences
Hui Huang, Georg Kuenze, Jarrod A Smith, Keenan C Taylor, Amanda M Duran, Arina Hadziselimovic, Jens Meiler, Carlos G Vanoye, Alfred L George, Charles R Sanders
Mutations that induce loss of function (LOF) or dysfunction of the human KCNQ1 channel are responsible for susceptibility to a life-threatening heart rhythm disorder, the congenital long QT syndrome (LQTS). Hundreds of KCNQ1 mutations have been identified, but the molecular mechanisms responsible for impaired function are poorly understood. We investigated the impact of 51 KCNQ1 variants with mutations located within the voltage sensor domain (VSD), with an emphasis on elucidating effects on cell surface expression, protein folding, and structure...
March 2018: Science Advances
Daniela Ponce-Balbuena, Guadalupe Guerrero-Serna, Carmen R Valdivia, Ricardo Caballero, F J Díez-Guerra, Eric N Jiménez-Vázquez, Rafael J Ramirez, Andre Monteiro da Rocha, Todd J Herron, Katherine F Campbell, B C Willis, Francisco J Alvarado, Manuel Zarzoso, Kuljeet Kaur, Marta Pérez-Hernández, Marcos Matamoros, Héctor H Valdivia, Eva Delpón, José Jalife
<u>Rationale:</u> In cardiomyocytes, NaV 1.5 and Kir2.1 channels interact dynamically as part of membrane bound macromolecular complexes. <u>Objective:</u> To test whether NaV 1.5 and Kir2.1 preassemble during early forward trafficking and travel together to common membrane microdomains. <u>Methods and Results:</u> In patch-clamp experiments, co-expression of trafficking deficient mutants Kir2.1Δ314-315 or Kir2.1R44A/R46A with wildtype (WT) NaV 1.5WT in heterologous cells reduced INa , compared to NaV 1...
March 7, 2018: Circulation Research
Jinjun Chen, Lingyong Li, Shao-Rui Chen, Hong Chen, Jing-Dun Xie, Rita E Sirrieh, David M MacLean, Yuhao Zhang, Meng-Hua Zhou, Vasanthi Jayaraman, Hui-Lin Pan
α2δ-1, commonly known as a voltage-activated Ca2+ channel subunit, is a binding site of gabapentinoids used to treat neuropathic pain and epilepsy. However, it is unclear how α2δ-1 contributes to neuropathic pain and gabapentinoid actions. Here, we show that Cacna2d1 overexpression potentiates presynaptic and postsynaptic NMDAR activity of spinal dorsal horn neurons to cause pain hypersensitivity. Conversely, Cacna2d1 knockdown or ablation normalizes synaptic NMDAR activity increased by nerve injury. α2δ-1 forms a heteromeric complex with NMDARs in rodent and human spinal cords...
February 27, 2018: Cell Reports
Julie Pilotte, See-Wing Chan, John B Farnum, William M Thomas, Zeev Smilansky, Peter W Vanderklish
mRNA translation is regulated by diverse mechanisms that converge at the initiation and elongation steps to determine the rate, profile, and localization of proteins synthesized. A consistently relevant feature of these mechanisms is the spatial re-distribution of translation machinery, a process of particular importance in neural cells. This process has, however, been largely overlooked with respect to its potential role in regulating the local concentration of cytoplasmic tRNAs, even as a multitude of data suggest that spatial regulation of the tRNA pool may help explain the remarkably high rates of peptide elongation...
February 16, 2018: European Journal of Cell Biology
Fumiaki Ando, Shinichi Uchida
Congenital nephrogenic diabetes insipidus (NDI) is characterized by defective urine concentrating ability. Symptomatic polyuria is present from birth, even with normal release of the antidiuretic hormone vasopressin by the pituitary. Over the last two decades, the aquaporin-2 (AQP2) gene has been cloned and the molecular mechanisms of urine concentration have been gradually elucidated. Vasopressin binds to the vasopressin type II receptor (V2R) in the renal collecting ducts and then activates AQP2 phosphorylation and trafficking to increase water reabsorption from urine...
February 24, 2018: Clinical and Experimental Nephrology
Tim Benke, Stephen F Traynelis
Twenty years ago, we reported from the Collingridge Lab that a single-channel conductance increase through α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)-type ionotropic glutamate receptors (AMPARs) could mediate one form of plasticity associated with long-term potentiation (LTP) in the hippocampus (Benke et al., Nature 395:793-797, 1998). Revealed through peak-scaled non-stationary fluctuation analysis (PS-NSFA, also known as noise analysis), this component of LTP could be exclusively mediated by direct increases in channel conductance or by increases in the number of high conductance synaptic AMPARs...
February 23, 2018: Neurochemical Research
Steven Molinarolo, Daniele Granata, Vincenzo Carnevale, Christopher A Ahern
Voltage-gated sodium channel (VGSC) beta (β) subunits have been called the "overachieving" auxiliary ion channel subunit. Indeed, these subunits regulate the trafficking of the sodium channel complex at the plasma membrane and simultaneously tune the voltage-dependent properties of the pore-forming alpha-subunit. It is now known that VGSC β-subunits are capable of similar modulation of multiple isoforms of related voltage-gated potassium channels, suggesting that their abilities extend into the broader voltage-gated channels...
February 21, 2018: Handbook of Experimental Pharmacology
Jie Wu, Yuka Mizusawa, Seiko Ohno, Wei-Guang Ding, Takashi Higaki, Qi Wang, Hirohiko Kohjitani, Takeru Makiyama, Hideki Itoh, Futoshi Toyoda, Andrew F James, Jules C Hancox, Hiroshi Matsuura, Minoru Horie
Congenital long QT syndrome (LQTS) caused by compound mutations is usually associated with more severe clinical phenotypes. We identified a LQTS family harboring three compound mutations in different genes (KCNQ1-R174C, hERG-E1039X and SCN5A-E428K). KCNQ1-R174C, hERG-E1039X and SCN5A-E428K mutations and/or relevant wild-type (WT) cDNAs were respectively expressed in mammalian cells. I Ks -like, I Kr -like, I Na -like currents and the functional interaction between KCNQ1-R174C and hERG-E1039X channels were studied using patch-clamp and immunocytochemistry techniques...
February 15, 2018: Scientific Reports
Yuanyuan Xu, Yu-Qing Jiang, Ce Li, Mindi He, W George Rusyniak, Naga Annamdevula, Juan Ochoa, Silas J Leavesley, Jiangping Xu, Thomas C Rich, Mike T Lin, Xiang-Ming Zha
Acid-sensing ion channels (ASICs) are the major proton receptor in the brain and a key mediator of acidosis-induced neuronal injuries in disease. Most of published data on ASIC function came from studies performed in mice, and relatively little is known about potential differences between human and mouse ASICs (hASIC and mASIC, respectively). This information is critical for us to better interpret the functional importance of ASICs in human disease. Here, we examined the expression of ASICs in acutely resected human cortical tissue...
February 15, 2018: FASEB Journal: Official Publication of the Federation of American Societies for Experimental Biology
Chunli Wang, Ying Chen, Bixia Zheng, Mengshu Zhu, Jia Fan, Juejin Wang, Zhanjun Jia, Songming Huang, Aihua Zhang
Inactivated variants in CLCNKB gene encoding the basolateral chloride channel ClC-Kb cause classic Bartter syndrome characterized by hypokalemic metabolic alkalosis and hyperreninemic hyperaldosteronism. Here we identified two cBS siblings presenting hypokalemia in a Chinese family due to novel compound heterozygous CLCNKB mutations (c.848_850delTCT/c.1755A>G). Compound heterozygosity was confirmed by amplifying and sequencing the patient's genomic DNA. The synonymous mutation c.1755A>G (Thr585Thr) was located at +2bp from the 5' splice donor site in exon 15, further transcript analysis demonstrated that this single nucleotide mutation causes exclusion of exon 15 in the cDNA from the proband and his mother...
February 14, 2018: American Journal of Physiology. Renal Physiology
Shanyu Cui, Hyewon Park, Hyelim Park, Dasom Mun, Seung Hyun Lee, Hyoeun Kim, Nuri Yun, Hail Kim, Michael Kim, Hui Nam Pak, Moon Hyoung Lee, Boyoung Joung
PURPOSE: The mechanisms underlying repolarization abnormalities during pregnancy are not fully understood. Although maternal serotonin (5-hydroxytryptamine, 5-HT) production is an important determinant for normal fetal development in mice, its role in mothers remains unclear. We evaluated the role of serotonin in ventricular repolarization in mice hearts via 5Htr3 receptor (Htr3a) and investigated the mechanism of QT-prolongation during pregnancy. MATERIALS AND METHODS: We measured current amplitudes and the expression levels of voltage-gated K⁺ (Kv) channels in freshly-isolated left ventricular myocytes from wild-type non-pregnant (WT-NP), late-pregnant (WT-LP), and non-pregnant Htr3a homozygous knockout mice (Htr3a(-/-)-NP)...
March 2018: Yonsei Medical Journal
Lusi Zhang, Youling Liang, Yedi Zhou, Huilan Zeng, Songbai Jia, Jingming Shi
Congenital cataract is leading cause of visual impairment and blindness in children worldwide. Approximately one-third of congenital cataract cases are familial, whose genetic etiology can be distinguished by targeted exome sequencing. Here, a three-generation congenital cataract pedigree was recruited, and physical and ophthalmologic examinations were taken. Targeted exome sequencing of 139 cataract-related genes was performed on the proband III:1. Sanger sequencing was used to validate the presence of variation identified via exome sequencing in family members and 200 controls...
2018: Tohoku Journal of Experimental Medicine
Federica Frigerio, Corey Flynn, Ye Han, Kyle Lyman, Joaquin N Lugo, Teresa Ravizza, Antoine Ghestem, Julika Pitsch, Albert Becker, Anne E Anderson, Annamaria Vezzani, Dane Chetkovich, Christophe Bernard
Neuroinflammation is consistently found in many neurological disorders, but whether or not the inflammatory response independently affects neuronal network properties is poorly understood. Here, we report that intracerebroventricular injection of the prototypical inflammatory molecule lipopolysaccharide (LPS) in rats triggered a strong and long-lasting inflammatory response in hippocampal microglia associated with a concomitant upregulation of Toll-like receptor (TLR4) in pyramidal and hilar neurons. This, in turn, was associated with a significant reduction of the dendritic hyperpolarization-activated cyclic AMP-gated channel type 1 (HCN1) protein level while Kv4...
February 9, 2018: Molecular Neurobiology
Xin Yang, Guorong Wen, Biguang Tuo, Fenglian Zhang, Hanxing Wan, Jialin He, Shiming Yang, Hui Dong
Background and Purpose: Although Ca2+ signaling may stimulate small intestinal ion secretion, little is known about its critical role and the molecular mechanisms of Ca2+-mediated biological action. Key Results: Activation of muscarinic receptors by carbachol(CCh) stimulated mouse duodenal Isc, which was significantly inhibited in Ca2+-free serosal solution and by several selective store-operated Ca2+ channels(SOC) blockers added to the serosal side of duodenal tissues...
January 9, 2018: Oncotarget
Hannah I Bishop, Melanie M Cobb, Michael Kirmiz, Laxmi K Parajuli, Danielle Mandikian, Ashleigh M Philp, Mikhail Melnik, Juha Kuja-Panula, Heikki Rauvala, Ryuichi Shigemoto, Karl D Murray, James S Trimmer
Voltage-gated K+ (Kv) channels play important roles in regulating neuronal excitability. Kv channels comprise four principal α subunits, and transmembrane and/or cytoplasmic auxiliary subunits that modify diverse aspects of channel function. AMIGO-1, which mediates homophilic cell adhesion underlying neurite outgrowth and fasciculation during development, has recently been shown to be an auxiliary subunit of adult brain Kv2.1-containing Kv channels. We show that AMIGO-1 is extensively colocalized with both Kv2...
2018: Frontiers in Molecular Neuroscience
Emily Bergbower, Clement Boinot, Inna Sabirzhanova, William Guggino, Liudmila Cebotaru
BACKGROUND/AIMS: The CFTR-Associated Ligand (CAL), a PDZ domain containing protein with two coiled-coil domains, reduces cell surface WT CFTR through degradation in the lysosome by a well-characterized mechanism. However, CAL's regulatory effect on ΔF508 CFTR has remained almost entirely uninvestigated. METHODS: In this study, we describe a previously unknown pathway for CAL by which it regulates the membrane expression of ΔF508 CFTR through arrest of ΔF508 CFTR trafficking in the endoplasmic reticulum (ER) using a combination of cell biology, biochemistry and electrophysiology...
January 29, 2018: Cellular Physiology and Biochemistry
Hao Yao, Cheng-Cheng Ji, Yun-Jiu Cheng, Xu-Miao Chen, Li-Juan Liu, Jun Fan, Su-Hua Wu
BACKGROUND: Recent studies have revealed that mutation in KCNE1, β-subunits of cardiac potassium channel, involved in ventricular fibrillation. Whereas its role in early repolarization syndrome (ERS) is less well understood. OBJECTIVE: To study whether mutant in KCNE1 is associated with ERS and explore the possible underlying molecular mechanisms. METHODS: Whole genome from four unrelated families with ERS was amplified and sequenced. Wild-type (WT) KCNE1 and/or KCNE1-S38G (S38G) were expressed in HEK293 cells with KCNQ1...
January 29, 2018: Experimental Cell Research
Matjaž Stenovec, Saša Trkov Bobnar, Tina Smolič, Marko Kreft, Vladimir Parpura, Robert Zorec
AIM: Alzheimer disease (AD) is largely considered a neuron-derived insult, but also involves failure of astroglia. A recent study indicated that mutated presenilin 1 (PS1M146V), a putative endoplasmic reticulum (ER) Ca2+ channel with decreased Ca2+ conductance, impairs the traffic of astroglial peptidergic vesicles. Whether other pathogenically relevant PS1 mutants, such as PS1ΔE9, which code for ER channel with putative increased Ca2+ conductance, similarly affect vesicle traffic, is unknown...
February 2, 2018: Acta Physiologica
Anouar Belkacemi, Xin Hui, Barbara Wardas, Matthias W Laschke, Ulrich Wissenbach, Michael D Menger, Peter Lipp, Andreas Beck, Veit Flockerzi
Voltage-gated calcium channels (Cavs) are major Ca2+ entry pathways in excitable cells. Their β subunits facilitate membrane trafficking of the channel's ion-conducting α1 pore and modulate its gating properties. We report that one β subunit, β3, reduces Ca2+ release following stimulation of phospholipase C-coupled receptors and inositol 1,4,5-trisphosphate (IP3 ) formation. This effect requires the SH3-HOOK domain of Cavβ3, includes physical β3/IP3 receptor interaction, and prevails when agonist-induced IP3 formation is bypassed by photolysis of caged IP3 ...
January 30, 2018: Cell Reports
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