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Channel trafficking

Ivan Kadurin, Laurent Ferron, Simon W Rothwell, James O Meyer, Leon R Douglas, Claudia S Bauer, Beatrice Lana, Wojciech Margas, Orpheas Alexopoulos, Manuela Nieto-Rostro, Wendy S Pratt, Annette C Dolphin
The auxiliary α2δ subunits of voltage-gated calcium channels are extracellular membrane-associated proteins, which are post-translationally cleaved into disulfide-linked polypeptides α2 and δ. We now show, using α2δ constructs containing artificial cleavage sites, that this processing is an essential step permitting voltage-dependent activation of plasma membrane N-type (CaV2.2) calcium channels. Indeed, uncleaved α2δ inhibits native calcium currents in mammalian neurons. By inducing acute cell-surface proteolytic cleavage of α2δ, voltage-dependent activation of channels is promoted, independent from the trafficking role of α2δ...
October 26, 2016: ELife
Zheng Zhang, Hannah A Ledford, Seojin Park, Wenying Wang, Sassan Rafizadeh, Hyo Jeong Kim, Wilson Xu, Ling Lu, Victor C Lau, Anne A Knowlton, Xiao-Dong Zhang, Ebenezer N Yamoah, Nipavan Chiamvimonvat
The normal function of ion channels depends critically on the precise subcellular localization and the number of channel proteins on the cell surface membrane. Small-conductance, Ca(2+) -activated K(+) channels (SK, KCa 2) are expressed in human atrial myocytes and responsible for shaping atrial action potentials. Understanding the mechanisms of SK channel trafficking may provide new insights into the regulation controlling the repolarization of atrial myocytes. We have previously demonstrated that the C and N termini of SK2 channels interact with actin-binding proteins, α-actinin2 and filamin A, respectively...
October 25, 2016: Journal of Physiology
Nasrin Dehghan-Nayeri, Mostafa Rezaei-Tavirani, Mir Davood Omrani, Ahmad Gharehbaghian, Kourosh Goudarzi Pour, Peyman Eshghi
Response to dexamethasone (DEXA), as a hallmark drug in the treatment of childhood acute lymphoblastic leukemia (ALL), is one of the pivotal prognostic factors in the prediction of outcome in ALL. Identification of predictive markers of chemoresistance is beneficial to selecting of the best therapeutic protocol with the lowest effect adverse. Hence, we aimed to find drug targets using the 2DE/MS proteomics study of a DEXA-resistant cell line (REH) as a model for poor DEXA responding patients before and after drug treatment...
October 24, 2016: Journal of Cell Communication and Signaling
Junting Huang, Gerald W Zamponi
Calcium entry via voltage gated calcium channels mediates a wide range of physiological functions, whereas calcium channel dysregulation has been associated with numerous pathophysiological conditions. There are myriad cell signaling pathways that act on voltage gated calcium channels to fine tune their activities and to regulate their cell surface expression. These regulatory mechanisms include the activation of G protein-coupled receptors and downstream phosphorylation events, and their control over calcium channel trafficking through direct physical interactions...
October 18, 2016: Current Opinion in Pharmacology
Benoîte Bourdin, Emilie Segura, Marie-Philippe Tétreault, Sylvie Lesage, Lucie Parent
Inherited or de novo mutations in cation-selective channels may lead to sudden cardiac death. Alteration in the plasma membrane trafficking of these multi-spanning transmembrane proteins, with or without change in channel gating, is often postulated to contribute significantly in this process. It has thus become critical to develop a method to quantify the change of the relative cell surface expression of cardiac ion channels on a large scale. Herein, a detailed protocol is provided to determine the relative total and cell surface expression of cardiac L-type calcium channels CaV1...
September 28, 2016: Journal of Visualized Experiments: JoVE
Can-Zhao Liu, Xiang-Yu Li, Ren-Hong Du, Min Gao, Ming-Ming Ma, Fei-Ya Li, Er-Wen Huang, Hong-Shuo Sun, Guan-Lei Wang, Yong-Yuan Guan
BACKGROUND: Previous research has demonstrated that ClC-3 is responsible for volume-regulated Cl(-)current (ICl.vol) in vascular smooth muscle cells (VSMCs). However, it is still not clear whether and how ClC-3 is transported to cell membranes, resulting in alteration ofICl.vol.Methods and Results:Volume-regulated chloride current (ICl.vol) was recorded by whole-cell patch clamp recording, and Western blotting and co-immunoprecipitation were performed to examine protein expression and protein-protein interaction...
October 19, 2016: Circulation Journal: Official Journal of the Japanese Circulation Society
Fahmy A Mamuya, Jose Luis Cano-Peñalver, Wei U Li, Diego Rodriguez-Puyol, Manuel Rodríguez-Puyol, Dennis Brown, Sergio de Frutos, Hua Jenny Lu
Within the past decade tremendous efforts have been made to understand the mechanism behind aquaporin-2 (AQP2) water channel trafficking and recycling, in order to open a path towards effective diabetes insipidus therapeutics. A recent study has shown that Integrin-Linked Kinase (ILK) conditional-knockdown mice developed polyuria along with decreased expression of AQP2. To understand whether ILK also regulates AQP2 trafficking in kidney tubular cells, we performed in vitro analysis using LLCPK1 cells stably expressing rat AQP2 (LLC-AQP2 cells)...
October 19, 2016: American Journal of Physiology. Renal Physiology
Yoshiaki Suzuki, Susumu Ohya, Hisao Yamamura, Wayne R Giles, Yuji Imaizumi
Large-conductance Ca(2+)-activated K(+) (BK) channels play essential roles in both excitable and non-excitable cells. For example, in chondrocytes, agonist-induced Ca(2+) release from intracellular store activates BK channels, and this hyperpolarizes these cells, augments Ca(2+) entry, and forms a positive feed-back mechanism for Ca(2+) signaling and stimulation-secretion coupling. In the present study, functional roles of a newly identified splice variant in the BK channel α subunit (BKαΔe2) were examined in a human chondrocyte cell line, OUMS-27, and in a HEK293 expression system...
October 7, 2016: Journal of Biological Chemistry
Manoj Yadav, Chandan Goswami
TRPV3 is a non-selective cationic channel and is important for several physiological functions. It can be activated by physiological temperature and selective endogenous and exogenous compounds. TRPV3 is one of the key ion channel involved in Ca(2+)-signaling in keratinocyte and thus involved in skin-related functions. Recently, naturally occurring mutations in TRPV3, namely G573A, G573S, G573C and W692G have been detected which are linked with the development of pathophysiological conditions such as Olmsted Syndrome (OS) and other skin disorders...
October 18, 2016: Channels
Michal Behuliak, Michal Bencze, Anna Vavrinova, Ivana Vaneckova, Josef Zicha
OBJECTIVE: Voltage-dependent calcium channels (VDCCs) play an important role in two major abnormalities observed in spontaneously hypertensive rats (SHR) - hyperactivity of sympathetic nervous system (SNS) and enhanced Ca influx to vascular smooth muscle cells (VSMC). α2δ subunit of VDCC, which promotes surface trafficking and modulates the biophysical properties of VDCC, was identified as a critical component of increased L-type VDCC calcium currents in arterial myocytes of SHR. On the other hand, N-type VDCCs control a neurotransmitter release in the peripheral sympathetic nervous system and play an important role in sympathetic hyperactivity in SHR...
September 2016: Journal of Hypertension
Juncal Fernández-Orth, Petra Ehling, Tobias Ruck, Susann Pankratz, Majella-Sophie Hofmann, Peter Landgraf, Daniela C Dieterich, Karl-Heinz Smalla, Thilo Kähne, Guiscard Seebohm, Thomas Budde, Heinz Wiendl, Stefan Bittner, Sven G Meuth
K2P 5.1 channels (also called TASK-2 or KCNK5) have already been shown to be relevant in the pathophysiology of autoimmune disease since they are known to be upregulated on peripheral and central T lymphocytes of multiple sclerosis (MS) patients. Moreover, overexpression of K2P 5.1 channels in vitro provokes enhanced T-cell effector functions. However, the molecular mechanisms regulating intracellular K2P 5.1 channel trafficking are unknown so far. Thus, the aim of the study is to elucidate the trafficking of K2P 5...
October 15, 2016: Traffic
Michael Groszmann, Hannah L Osborn, John R Evans
Aquaporins are channel proteins that function to increase the permeability of biological membranes. In plants, aquaporins are encoded by multigene families that have undergone substantial diversification in land plants. The Plasma membrane Intrinsic Proteins (PIPs) subfamily of aquaporins are of particular interest given their potential to improve plant water relations and photosynthesis. Flowering plants have between 7 and 28 PIP genes. Their expression varies with tissue and cell type, through development and in response to a variety of factors, contributing to the dynamic and tissue specific control of permeability...
October 14, 2016: Plant, Cell & Environment
Stephanie Chin, Maurita Hung, Christine E Bear
Cystic fibrosis transmembrane conductance regulator (CFTR) channel gating is predominantly regulated by protein kinase A (PKA)-dependent phosphorylation. In addition to regulating CFTR channel activity, PKA phosphorylation is also involved in enhancing CFTR trafficking and mediating conformational changes at the interdomain interfaces of the protein. The major cystic fibrosis (CF)-causing mutation is the deletion of phenylalanine at position 508 (F508del); it causes many defects that affect CFTR trafficking, stability, and gating at the cell surface...
October 8, 2016: Cellular and Molecular Life Sciences: CMLS
Elvira Sondo, Emanuela Pesce, Valeria Tomati, Monica Marini, Nicoletta Pedemonte
BACKGROUND: Deletion of phenylalanine 508 is the most frequent mutation causing cystic fibrosis. It causes multiple defects: 1) misfolding of the protein causing retention at the ER (processing defect); 2) reduced channel activity (gating defect); 3) reduced plasma membrane residency time due to increased internalization rate and defective recycling. METHODS: Druggability of F508del-CFTR was demonstrated by several studies. Correctors are molecules able to improve maturation and trafficking to the membrane of F508del-CFTR...
October 6, 2016: Current Pharmaceutical Design
Min Lin, Danielle Sambo, Habibeh Khoshbouei
: Methamphetamine (METH) is a substrate for the dopamine transporter that increases extracellular dopamine levels by competing with dopamine uptake and increasing reverse transport of dopamine via the transporter. METH has also been shown to alter the excitability of dopamine neurons. The mechanism of METH regulation of the intrinsic firing behaviors of dopamine neurons is less understood. Here we identified an unexpected and unique property of METH on the regulation of firing activity of mouse dopamine neurons...
October 5, 2016: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
Sukanya Lodh, Junji Yano, Megan S Valentine, Judith L Van Houten
Paramecium cells swim by beating their cilia, and make turns by transiently reversing their power stroke. Reversal is caused by Ca(2+) entering the cilium through voltage-gated Ca(2+) (CaV) channels that are found exclusively in the cilia. As ciliary Ca(2+) levels return to normal, the cell pivots and swims forward in a new direction. Thus, the activation of the CaV channels causes cells to make a turn in their swimming paths. For 45 years, the physiological characteristics of the Paramecium ciliary CaV channels have been known, but the proteins were not identified until recently, when the P...
October 1, 2016: Journal of Experimental Biology
Carlos M Farinha, Sara Canato
CFTR biogenesis starts with its co-translational insertion into the membrane of endoplasmic reticulum and folding of the cytosolic domains, towards the acquisition of a fully folded compact native structure. Efficiency of this process is assessed by the ER quality control system that allows the exit of folded proteins but targets unfolded/misfolded CFTR to degradation. If allowed to leave the ER, CFTR is modified at the Golgi and reaches the post-Golgi compartments to be delivered to the plasma membrane where it functions as a cAMP- and phosphorylation-regulated chloride/bicarbonate channel...
October 3, 2016: Cellular and Molecular Life Sciences: CMLS
Mayanka Awasthi, Peeyush Ranjan, Komal Sharma, Sindhu Kandoth Veetil, Suneel Kateriya
The bacterial type rhodopsins are present in all the three domains of life. In contrast to the animal type rhodopsin that performs mainly sensory functions in higher eukaryotes, the bacterial type rhodopsin could function as ion channel, pumps and as sensory proteins. The functioning of rhodopsin in higher eukaryotes requires the transport of rhodopsin from its site of synthesis to the ciliated outer segment of the photoreceptive cells. However, the trafficking of bacterial type rhodopsin from its site of synthesis to the position of action is not characterized...
October 3, 2016: Scientific Reports
Peng Tan, Lian He, Gang Han, Yubin Zhou
Microbial opsin-based optogenetic tools have been transformative for neuroscience. To extend optogenetic approaches to the immune system to remotely control immune responses with superior spatiotemporal precision, pioneering tools have recently been crafted to modulate lymphocyte trafficking, inflammasome activation, dendritic cell (DC) maturation, and antitumor immunity through the photoactivation of engineered chemokine receptors and calcium release-activated calcium channels. We highlight herein some conceptual design strategies for installing light sensitivities into the immune signaling network and, in parallel, we propose potential solutions for in vivo optogenetic applications in living organisms with near-infrared light-responsive upconversion nanomaterials...
September 28, 2016: Trends in Biotechnology
Meng Yan, Pan Fan, Yanhui Shi, Lifang Feng, Junnan Wang, Ge Zhan, Baoxin Li
Diastereoisomers of quinidine and quinine are used to treat arrhythmia and malaria, respectively. It has been reported that both drugs block the hERG (human ether-a-go-go-related gene) potassium channel which is essential for myocardium repolarization. Abnormality of repolarization increases risk of arrhythmia. The aim of our research is to study and compare the impacts of quinidine and quinine on hERG. Results show that both drugs block the hERG channel, with quinine 14-fold less potent than quinidine. In addition, they presented distinct impacts on channel dynamics...
2016: International Journal of Molecular Sciences
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