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calnexin and channel protein

Juliane Proft, Yuriy Rzhepetskyy, Joanna Lazniewska, Fang-Xiong Zhang, Stuart M Cain, Terrance P Snutch, Gerald W Zamponi, Norbert Weiss
Low-voltage-activated T-type calcium channels are essential contributors to the functioning of thalamocortical neurons by supporting burst-firing mode of action potentials. Enhanced T-type calcium conductance has been reported in the Genetic Absence Epilepsy Rat from Strasbourg (GAERS) and proposed to be causally related to the overall development of absence seizure activity. Here, we show that calnexin, an endoplasmic reticulum integral membrane protein, interacts with the III-IV linker region of the Cav3...
September 14, 2017: Scientific Reports
Dahai Yu, Lin Lv, Li Fang, Bo Zhang, Junnan Wang, Ge Zhan, Lei Zhao, Xin Zhao, Baoxin Li
The human ether-a-go-go-related gene (hERG) potassium channel conducts rapid delayed rectifier potassium currents (IKr) and contributes to phase III cardiac action potential repolarization. Drugs inhibit hERG channels by binding to aromatic residues in hERG helixes. Berberine (BBR) has multiple actions, and its hydrogenated derivative dihydroberberine (DHB) is a potential candidate for developing new drugs. Previous studies have demonstrated that BBR blocks hERG channels and prolongs action potential duration (APD)...
2017: PloS One
Xin Wang, Setsuko Komatsu
Flooding and drought are disadvantageous environmental conditions that induce cytosolic calcium in soybean. To explore the effects of flooding- and drought-induced increases in calcium, a gel-free/label-free proteomic analysis was performed. Cytosolic calcium was decreased by blocking calcium channels in the endoplasmic reticulum (ER) and plasma membrane under both stresses. Calnexin, protein disulfide isomerase, heat shock proteins and thioredoxin were predominantly affected as the ER proteins in response to calcium, and ER-associated degradation-related proteins of HCP-like superfamily protein were up-regulated under stress exposure and then down-regulated...
August 1, 2017: Plant & Cell Physiology
Shenghua Zhang, Hailin Zheng, Qiuyi Chen, Yuan Chen, Sha Wang, Ling Lu, Shizhu Zhang
The Ca(2+)-mediated signaling pathway is crucial for environmental adaptation in fungi. Here we show that calnexin, a molecular chaperone located in the endoplasmic reticulum (ER), plays an important role in regulating the cytosolic free calcium concentration ([Ca(2+)]c) in Aspergillus nidulans Inactivation of calnexin (ClxA) in A. nidulans caused severe defects in hyphal growth and conidiation under ER stress caused by the ER stress-inducing agent dithiothreitol (DTT) or high temperature. Importantly, defects in the ΔclxA mutant were restored by the addition of extracellular calcium...
August 1, 2017: Applied and Environmental Microbiology
Xi Xiao, Changyan Chen, Tian-Ming Yu, Jiayao Ou, Menglong Rui, Yuanfen Zhai, Yijing He, Lei Xue, Margaret S Ho
Neuronal activity mediated by voltage-gated channels provides the basis for higher-order behavioral tasks that orchestrate life. Chaperone-mediated regulation, one of the major means to control protein quality and function, is an essential route for controlling channel activity. Here we present evidence that Drosophila ER chaperone Calnexin colocalizes and interacts with the α subunit of sodium channel Paralytic. Co-immunoprecipitation analysis indicates that Calnexin interacts with Paralytic protein variants that contain glycosylation sites Asn313, 325, 343, 1463, and 1482...
2017: Frontiers in Molecular Neuroscience
Paul Christian Vicente, Jin Young Kim, Jeong-Ju Ha, Min-Young Song, Hyun-Kyung Lee, Dong-Hyun Kim, Jin-Sung Choi, Kang-Sik Park
The potassium ion channel Kv3.1b is a member of a family of voltage-gated ion channels that are glycosylated in their mature form. In the present study, we demonstrate the impact of N-glycosylation at specific asparagine residues on the trafficking of the Kv3.1b protein. Large quantities of asparagine 229 (N229)-glycosylated Kv3.1b reached the plasma membrane, whereas N220-glycosylated and unglycosylated Kv3.1b were mainly retained in the endoplasmic reticulum (ER). These ER-retained Kv3.1b proteins were susceptible to degradation, when co-expressed with calnexin, whereas Kv3...
January 2018: Journal of Cellular Physiology
Ning Li, Moonhee Park, Shengxiang Xiao, Zhi Liu, Luis A Diaz
Darier's disease (DD) is an autosomal dominantly inherited skin disorder caused by mutations in sarco/endoplasmic reticulum Ca(2+) -ATPase 2 (SERCA2), a Ca(2+) pump that transports Ca(2+) from the cytosol to the endoplasmic reticulum (ER). Loss of desmosomes and keratinocyte cohesion is a characteristic feature of DD. Desmosomal cadherins (DC) are Ca(2+) -dependent transmembrane adhesion proteins of desmosomes, which are mislocalized in the lesional but not perilesional skin of DD. We show here that inhibition of SERCA2 by 2 distinct inhibitors results in accumulation of DC precursors in keratinocytes, indicating ER-to-Golgi transport of nascent DC is blocked...
April 2017: Traffic
Laura-Nadine Schuhmacher, Ewan St John Smith
Acid-sensing ion channels (ASICs) are a family of ion channels comprised of six subunits encoded by four genes and they are expressed throughout the peripheral and central nervous systems. ASICs have been implicated in a wide range of physiological and pathophysiological processes: pain, breathing, synaptic plasticity and excitotoxicity. Unlike mice and humans, naked mole-rats do not perceive acid as a noxious stimulus, even though their sensory neurons express functional ASICs, likely an adaptation to living in a hypercapnic subterranean environment...
December 13, 2016: Molecular Brain
Gustavo Frindt, Diego Gravotta, Lawrence G Palmer
The epithelial Na channel (ENaC) forms a pathway for Na(+) reabsorption in the distal nephron, and regulation of these channels is essential for salt homeostasis. In the rat kidney, ENaC subunits reached the plasma membrane in both immature and fully processed forms, the latter defined by either endoglycosidase H-insensitive glycosylation or proteolytic cleavage. Animals adapted to a low-salt diet have increased ENaC surface expression that is specific for the mature forms of the subunit proteins and is similar (three- to fourfold) for α, β, and γENaC...
March 2016: Journal of General Physiology
Danny Y T Liu, Penelope M C Smith, Deborah A Barton, David A Day, Robyn L Overall
Calnexin (CNX) is a highly conserved endoplasmic reticulum (ER) chaperone protein. Both calnexin and the homologous ER-lumenal protein, calreticulin, bind calcium ions and participate in protein folding. There are two calnexins in Arabidopsis thaliana, CNX1 and CNX2. GUS expression demonstrated that these are expressed in most Arabidopsis tissues throughout development. Calnexin transfer DNA (T-DNA) mutant lines exhibited increased transcript abundances of a number of other ER chaperones, including calreticulins, suggesting a degree of redundancy...
January 2017: Protoplasma
Yuan-Qi Shi, Meng Yan, Li-Rong Liu, Xiao Zhang, Xue Wang, Huai-Ze Geng, Xin Zhao, Bao-Xin Li
BACKGROUND/AIMS: Abnormal QT prolongation is the most prominent cardiac electrical disturbance in patients with diabetes mellitus (DM). It is well known that the human ether-ago-go-related gene (hERG) controls the rapid delayed rectifier K+ current (IKr) in cardiac cells. The expression of the hERG channel is severely down-regulated in diabetic hearts, and this down-regulation is a critical contributor to the slowing of repolarization and QT prolongation. However, the intracellular mechanisms underlying the diabetes-induced hERG deficiency remain unknown...
2015: Cellular Physiology and Biochemistry
Dong-Yun Han, Bo-Jhih Guan, Ya-Juan Wang, Maria Hatzoglou, Ting-Wei Mu
Gamma-aminobutyric acid type A (GABAA) receptors are the primary inhibitory ion channels in the mammalian central nervous system and play an essential role in regulating inhibition-excitation balance in neural circuits. The α1 subunit harboring the D219N mutation of GABAA receptors was reported to be retained in the endoplasmic reticulum (ER) and traffic inefficiently to the plasma membrane, leading to a loss of function of α1(D219N) subunits and thus idiopathic generalized epilepsy (IGE). We present the use of small molecule proteostasis regulators to enhance the forward trafficking of α1(D219N) subunits to restore their function...
September 18, 2015: ACS Chemical Biology
Kaiping Zhang, Duo Zhi, Ting Huang, Yan Gong, Meng Yan, Chen Liu, Ting Wei, Zengxiang Dong, Baoxin Li, Baofeng Yang
AIMS: The human ether-a-go-go-related gene (hERG) encodes the α subunit of the IKr, which plays an essential role in repolarization of action potentials. hERG channels are targeted by various pro-arrhythmic drugs. Berberine (BBR) was previously found to acutely inhibit hERG currents and prolong action potential duration. The present study aimed to determine long-term effects of BBR on the expression of 135kDa/155kDa hERG and the mechanism. METHODS AND RESULTS: hERG expression was assessed by western blot...
2014: Cellular Physiology and Biochemistry
Xin Zhao, Kai-Ping Zhang, Ting Huang, Cai-Chuan Yan, Li-Rong Liu, Qi-Lei Zhu, Feng-Feng Guo, Chen Liu, Bao-Xin Li
Arsenic trioxide (As2O3) is used to treat acute promyelocytic leukemia. However, the cardiotoxicity of long QT syndrome restricts its clinical application. Previous studies showed that As2O3 can damage the human ether-a-go-go-related gene (hERG) current via disturbing its trafficking to cellular membrane. This study aimed to investigate whether the As2O3-insulted hERG channel can be rescued by resveratrol, a recognized cardioprotective agent. The whole-cell patch clamp technique was used to record the hERG current and action potential duration...
November 2014: Naunyn-Schmiedeberg's Archives of Pharmacology
C Norez, C Vandebrouck, J Bertrand, S Noel, E Durieu, N Oumata, H Galons, F Antigny, A Chatelier, P Bois, L Meijer, F Becq
BACKGROUND AND PURPOSE: The most common mutation in cystic fibrosis (CF), F508del, causes defects in trafficking, channel gating and endocytosis of the CF transmembrane conductance regulator (CFTR) protein. Because CF is an orphan disease, therapeutic strategies aimed at improving mutant CFTR functions are needed to target the root cause of CF. EXPERIMENTAL APPROACH: Human CF airway epithelial cells were treated with roscovitine 100 μM for 2 h before CFTR maturation, expression and activity were examined...
November 2014: British Journal of Pharmacology
Yongjun Zhu, Ruoting Men, Maoyao Wen, Xiaolin Hu, Xiaojing Liu, Li Yang
AIMS: Proliferation is a 'multiplier' for extracellular matrix production and contraction of activated hepatic stellate cells (HSC) in fibrotic liver. Transient receptor potential melastatin-like 7 channels (TRPM7) are implicated in the survival and proliferation of several kinds of cells. This study was aimed to investigate the effect of TRPM7 blocker 2-APB on survival and proliferation of HSC and the underlying mechanisms. MAIN METHODS: Rat HSC were stimulated by 2-APB for 24 h and then collected for further use...
January 14, 2014: Life Sciences
Xiao-Jing Di, Dong-Yun Han, Ya-Juan Wang, Mark R Chance, Ting-Wei Mu
GABA(A) receptors are the primary inhibitory ion channels in the mammalian central nervous system. The A322D mutation in the α1 subunit of GABA(A) receptors is known to result in its degradation and reduce its cell surface expression, leading to loss of GABAA receptor function in autosomal dominant juvenile myoclonic epilepsy. Here, we show that SAHA, a FDA-approved drug, increases the transcription of the α1(A322D) subunit, enhances its folding and trafficking posttranslationally, increases its cell surface level, and restores the GABA-induced maximal current in HEK293 cells expressing α1(A322D)β2γ2 receptors to 10% of that for wild-type receptors...
December 19, 2013: Chemistry & Biology
Yuhong Wang, Dimitar P Zankov, Min Jiang, Mei Zhang, Scott C Henderson, Gea-Ny Tseng
Our goals are to simultaneously determine the three-dimensional distribution patterns of KCNQ1 and KCNE1 in cardiac myocytes and to study the mechanism and functional implications for variations in KCNQ1/KCNE1 colocalization in myocytes. We monitored the distribution patterns of KCNQ1, KCNE1, and markers for subcellular compartments/organelles using immunofluorescence/confocal microscopy and confirmed the findings in ventricular myocytes by directly observing fluorescently tagged KCNQ1-GFP and KCNE1-dsRed expressed in these cells...
December 6, 2013: Journal of Biological Chemistry
Nicolas Bousette, Cynthia Abbasi, Roxana Chis, Anthony O Gramolini
Calnexin (CNX) is an endoplasmic reticulum (ER) quality control chaperone that has been implicated in ER stress. ER stress is a prominent pathological feature of various pathologic conditions, including cardiovascular diseases. However, the role of CNX and ER stress has not been studied in the heart. In the present study, we aimed to characterize the role of CNX in cardiomyocyte physiology with respect to ER stress, apoptosis, and cardiomyocyte Ca(2+) cycling. We demonstrated significantly decreased CNX mRNA and protein levels by LentiVector mediated transduction of targeting shRNAs...
March 2014: Journal of Cellular Physiology
Hiroshi Matsuzaki, Takahiro Fujimoto, Masatoshi Tanaka, Senji Shirasawa
Regulation of intracellular Ca(2+) concentration is critical in numerous biological processes. Inositol 1,4,5-trisphosphate receptor (IP3R) functions as the Ca(2+) release channel on endoplasmic reticulum (ER) membranes. Much attention has been dedicated to mitochondrial Ca(2+) uptake via mitochondria-associated ER membranes (MAM) which is involved in intracellular Ca(2+) homeostasis; however, the molecular mechanisms that link the MAM to mitochondria still remain elusive. We previously reported that Tespa1 (thymocyte-expressed, positive selection-associated gene 1) expressed in lymphocytes physically interacts with IP3R...
April 12, 2013: Biochemical and Biophysical Research Communications
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