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Michael Poteser, Gerd Leitinger, Elisabeth Pritz, Dieter Platzer, Irene Frischauf, Christoph Romanin, Klaus Groschner
Nanometer-spaced appositions between endoplasmic reticulum and plasma membrane (ER-PM junctions) stabilized by membrane-joining protein complexes are critically involved in cellular Ca(2+)-handling and lipid trafficking. ER-PM junctional architecture and plasticity associated with inter-membrane communication are as yet barely understood. Here, we introduce a method to precisely characterize ER-PM junction morphology and dynamics with high temporal resolution and minimal disturbance of junctional intermembrane communication...
October 19, 2016: Scientific Reports
Sher Ali, Tao Xu, Xiaolan Xu
Ca(2+) release-activated Ca(2+) (CRAC) channels play an essential role in the immune system. The pore-forming subunit, Orai1, is an important pharmacological target. Here, we summarize the recent discoveries on the structure-function relationship of Orai1, as well as its interaction with the native channel opener STIM1 and chemical modulator 2-aminoethoxydiphenyl borate (2-APB). We first introduce the critical structural elements of Orai1, which include a Ca(2+) accumulating region (CAR), ion selectivity filter, hydrophobic centre, basic region, extended transmembrane orai1 N-terminal (ETON), transmembrane (TM) regions 2 and 3, P245 bend, (263) SHK(265) hinge linker and L273-L276 hydrophobic patch...
October 18, 2016: Journal of Physiology
Jian Shi, Francesc Miralles, Lutz Birnbaumer, William A Large, Anthony P Albert
In vascular smooth muscle cells (VSMCs), stimulation of TRPC1-based SOCs mediate Ca(2+) entry pathways which regulate contractility, proliferation and migration. It is therefore important to understand how these channels are activated. Studies have shown that stimulation of TRPC1-based SOCs requires Gαq/PLCβ1 activities and PKC phosphorylation, but it is unclear how store depletion stimulates this gating pathway. The present work examines this issue by focusing on the role of STIM1, an endo/sarcoplasmic reticulum Ca(2+) sensor...
October 18, 2016: Journal of Physiology
Ming Wei, Yandong Zhou, Aomin Sun, Guolin Ma, Lian He, Lijuan Zhou, Shuce Zhang, Jin Liu, Shenyuan L Zhang, Donald L Gill, Youjun Wang
Store-operated Ca(2+) entry (SOCE) mediated by STIM1 and Orai1 is crucial for Ca(2+) signaling and homeostasis in most cell types. 2-Aminoethoxydiphenyl borate (2-APB) is a well-described SOCE inhibitor, but its mechanisms of action remain largely elusive. Here, we show that 2-APB does not affect the dimeric state of STIM1, but enhances the intramolecular coupling between the coiled-coil 1 (CC1) and STIM-Orai-activating region (SOAR) of STIM1, with subsequent reduction in the formation of STIM1 puncta in the absence of Orai1 overexpression...
October 10, 2016: Pflügers Archiv: European Journal of Physiology
Axel R Concepcion, Martin Vaeth, Larry E Wagner, Miriam Eckstein, Lee Hecht, Jun Yang, David Crottes, Maximilian Seidl, Hyosup P Shin, Carl Weidinger, Scott Cameron, Stuart E Turvey, Thomas Issekutz, Isabelle Meyts, Rodrigo S Lacruz, Mario Cuk, David I Yule, Stefan Feske
Eccrine sweat glands are essential for sweating and thermoregulation in humans. Loss-of-function mutations in the Ca2+ release-activated Ca2+ (CRAC) channel genes ORAI1 and STIM1 abolish store-operated Ca2+ entry (SOCE), and patients with these CRAC channel mutations suffer from anhidrosis and hyperthermia at high ambient temperatures. Here we have shown that CRAC channel-deficient patients and mice with ectodermal tissue-specific deletion of Orai1 (Orai1K14Cre) or Stim1 and Stim2 (Stim1/2K14Cre) failed to sweat despite normal sweat gland development...
October 10, 2016: Journal of Clinical Investigation
Ching Man Chan, Jacqueline T M Aw, Sarah E Webb, Andrew L Miller
In zebrafish embryos, distinct Ca2+ transients are localized to the early cleavage furrows during the first few cell division cycles. These transients are generated mainly by release via IP3Rs in the endoplasmic reticulum, and they are necessary for furrow positioning, propagation, deepening and apposition. We previously showed, via the use of inhibitors, that store-operated Ca2+ entry (SOCE) also appears to be essential for maintaining the IP3R-mediated elevated levels of [Ca2+]i for the extended periods required for the completion of successful furrow deepening and daughter cell apposition in these large embryonic cells...
October 5, 2016: Zygote: the Biology of Gametes and Early Embryos
Wei Rao, Cheng Peng, Lei Zhang, Ning Su, Kai Wang, Hao Hui, Shu-Hui Dai, Yue-Fan Yang, Peng Luo, Zhou Fei
Calcium disequilibrium is extensively involved in oxidative stress-induced neuronal injury. Although Homer1a is known to regulate several neuronal calcium pathways, its effects on, or its exact relationship with, oxidative stress-induced neuronal injury has not yet been fully elucidated. We found that Homer1a protected HT-22 cells from glutamate-induced oxidative stress injury by inhibiting final-phase intracellular calcium overload and mitochondrial oxidative stress. In these cells, stromal interactive molecule 1 (STIM1) puncta, but not the protein level, was significantly increased after glutamate treatment...
September 29, 2016: Scientific Reports
Judith A Stolwijk, Xuexin Zhang, Maxime Gueguinou, Wei Zhang, Khalid Matrougui, Christian Renken, Mohamed Trebak
Endothelial barrier function is tightly regulated by plasma membrane receptors and is crucial for tissue fluid homeostasis; its dysfunction causes disease, including sepsis and inflammation. The ubiquitous activation of Ca2+ signaling upon phospholipase C (PLC)-coupled receptor ligation leads quite naturally to the assumption that Ca2+ signaling is required for receptor-regulated endothelial barrier function. This widespread hypothesis draws analogy from smooth muscle and proposes the requirement of G protein coupled receptor (GPCR)-generated Ca2+ signaling in activating the endothelial contractile apparatus and generating inter-endothelial gaps...
September 13, 2016: Journal of Biological Chemistry
Dalia Alansary, Barbara Schmidt, Kathrin Dörr, Ivan Bogeski, Heiko Rieger, Achim Kless, Barbara A Niemeyer
Store-operated Ca(2+) entry mediated by STIM1-gated Orai1 channels is essential to activate immune cells and its inhibition or gain-of-function can lead to immune dysfunction and other pathologies. Reactive oxygen species interacting with cysteine residues can alter protein function. Pretreatment of the Ca(2+) selective Orai1 with the oxidant H2O2 reduces ICRAC with C195, distant to the pore, being its major redox sensor. However, the mechanism of inhibition remained elusive. Here we combine experimental and theoretical approaches and show that oxidation of Orai1 leads to reduced subunit interaction, slows diffusion and that either oxidized C195 or its oxidomimetic mutation C195D located at the exit of transmembrane helix 3 virtually eliminates channel activation by intramolecular interaction with S239 of transmembrane helix 4, thereby locking the channel in a closed conformation...
2016: Scientific Reports
Zili Zhang, Jian Wang, Jianxing He, Xiansheng Zeng, Xindong Chen, Mingmei Xiong, Qipeng Zhou, Meihua Guo, Defu Li, Wenju Lu
OBJECTIVE: Store operated calcium channels (SOCCs) and Receptor-operated calcium channels (ROCCs) are important pathways participating in regulation of intracellular Ca(2 +) concentration in various cell types. The purpose of our study is to determine whether genetic variations in key components of SOCCs and ROCCs are associated with lung cancer risk. METHODS: We identified 236 tagSNPs in 9 key genes related to SOCCs and ROCCs (TRPC1, TRPC3, TRPC4, TRPC6, TRPC7, ORAI1, ORAI2, STIM1, and STIM2) and evaluated their association with lung cancer risk in a two-stage case-control study with a total of 2433 lung cancer cases and 2433 cancer-free controls using Illumina high throughput genotyping platform...
September 2016: Meta Gene
Amit Jairaman, Chelsea H Maguire, Robert P Schleimer, Murali Prakriya
Aberrant immune responses to environmental allergens including insect allergens from house dust mites and cockroaches contribute to allergic inflammatory diseases such as asthma in susceptible individuals. Airway epithelial cells (AECs) play a critical role in this process by sensing the proteolytic activity of allergens via protease-activated receptors (PAR2) to initiate inflammatory and immune responses in the airway. Elevation of cytosolic Ca(2+) is an important signaling event in this process, yet the fundamental mechanism by which allergens induce Ca(2+) elevations in AECs remains poorly understood...
2016: Scientific Reports
Benjamin Chun-Kit Tong, Claire Shuk-Kwan Lee, Wing-Hei Cheng, Kwok-On Lai, J Kevin Foskett, King-Ho Cheung
Some forms of familial Alzheimer's disease (FAD) are caused by mutations in presenilins (PSs), catalytic components of a γ-secretase complex that cleaves target proteins, including amyloid precursor protein (APP). Calcium (Ca(2+)) dysregulation in cells with these FAD-causing PS mutants has been attributed to attenuated store-operated Ca(2+) entry [SOCE; also called capacitative Ca(2+) entry (CCE)]. CCE occurs when STIM1 detects decreases in Ca(2+) in the endoplasmic reticulum (ER) and activates ORAI channels to replenish Ca(2+) stores in the ER...
2016: Science Signaling
Jessica Sabourin, Florent Allagnat
Normal plasma glucose level is ensured by the action of insulin, the major hypoglycemic hormone. Therefore, it is not surprising that insulin release from pancreatic β-cells of the Langerhans islets is controlled by an array of balanced mechanisms in which glucose plays the leading role. Glucose triggers insulin secretion through the well described pathway of ATP-driven closure of ATP-sensitive potassium channels (KATP), depolarization of the plasma membrane and opening of the voltage-dependent Ca2+ channels (VDCC)...
September 2, 2016: Journal of Molecular Endocrinology
Ellie M Carrell, Aundrea R Coppola, Helen J McBride, Robert T Dirksen
Orai1 is a transmembrane protein that forms homomeric, calcium-selective channels activated by stromal interaction molecule 1 (STIM1) after depletion of intracellular calcium stores. In adult skeletal muscle, depletion of sarcoplasmic reticulum calcium activates STIM1/Orai1-dependent store-operated calcium entry. Here, we used constitutive and inducible muscle-specific Orai1 knockout (KO) mice to determine the acute and long-term developmental effects of Orai1 ablation on muscle structure and function. Skeletal muscles from constitutive, muscle-specific Orai1 KO mice exhibited normal postnatal growth and fiber type differentiation...
September 1, 2016: FASEB Journal: Official Publication of the Federation of American Societies for Experimental Biology
Susana Cubillos, Johannes Norgauer
Psoriasis is an inflammatory skin disease with or without joint involvement. In this disease, the thickened epidermis and impaired barrier are associated with altered calcium gradients. Calcium and vitamin D are known to play important roles in keratinocyte differentiation and bone metabolism. Intracellular calcium is regulated by calcium-sensing receptor (CASR), calcium release-activated calcium modulator (ORAI) and stromal interaction molecule (STIM). Other proteins modulated by vitamin D play important roles in calcium regulation e...
October 2016: International Journal of Molecular Medicine
Xuhua Mao, Jianfeng Zhang, Yue Han, Chao Luan, Yu Hu, Zhimin Hao, Min Chen
Antigen specific B cells undergo a process termed affinity maturation in the germinal centers of secondary lymphoid organs where B cells with high affinity receptors are selected to mature into antibody-producing cells or to the memory B cell pool. It is known that B cell antigen receptor (BCR) signaling plays pivotal role in this selection process. Calcium influx is an essential component of BCR signaling. The current report is to determine the effect of calcium influx on antibody affinity maturation. In our studies, mice deficient for both endoplasmic reticulum calciumsensor Stim1 and Stim2 was immunized with T-cell dependent and independent antigens...
August 27, 2016: Oncotarget
Haidong Yao, Ruifeng Fan, Xia Zhao, Wenchao Zhao, Wei Liu, Jie Yang, Hamid Sattar, Jinxin Zhao, Ziwei Zhang, Shiwen Xu
Selenium (Se) deficiency induces Ca2+ leak and calcification in mammal skeletal muscles; however, the exact mechanism is still unclear. In the present study, both Se-deficient chicken muscle models and selenoprotein W (SelW) gene knockdown myoblast and embryo models were used to study the mechanism. The results showed that Se deficiency-induced typical muscular injuries accompanied with Ca2+ leak and oxidative stress (P < 0.05) injured the ultrastructure of the sarcoplasmic reticulum (SR) and mitochondria; decreased the levels of the Ca2+ channels, SERCA, SLC8A, CACNA1S, ORAI1, STIM1, TRPC1, and TRPC3 (P < 0...
August 20, 2016: Oncotarget
Elsie Samakai, Robert Hooper, Kayla A Martin, Maya Shmurak, Yi Zhang, Dietmar J Kappes, Italo Tempera, Jonathan Soboloff
Antigen presentation to the T cell receptor leads to sustained cytosolic Ca(2+) elevation, which is critical for T-cell activation. We previously showed that in activated T cells, Ca(2+) clearance is inhibited by the endoplasmic reticulum Ca(2+) sensor stromal interacting molecule 1 (STIM1) via association with the plasma membrane Ca(2+)/ATPase 4 (PMCA4) Ca(2+) pump. Having further observed that expression of both proteins is increased in activated T cells, the current study focused on mechanisms regulating both up-regulation of STIM1 and PMCA4 and assessing how this up-regulation contributes to control of Ca(2+) clearance...
August 15, 2016: FASEB Journal: Official Publication of the Federation of American Societies for Experimental Biology
Catherine A Rivet, Ariel S Kniss-James, Margaret A Gran, Anish Potnis, Abby Hill, Hang Lu, Melissa L Kemp
T cells reach a state of replicative senescence characterized by a decreased ability to proliferate and respond to foreign antigens. Calcium release associated with TCR engagement is widely used as a surrogate measure of T cell response. Using an ex vivo culture model that partially replicates features of organismal aging, we observe that while the amplitude of Ca2+ signaling does not change with time in culture, older T cells exhibit faster Ca2+ rise and a faster decay. Gene expression analysis of Ca2+ channels and pumps expressed in T cells by RT-qPCR identified overexpression of the plasma membrane CRAC channel subunit ORAI1 and PMCA in older T cells...
2016: PloS One
Renyi Liu, Wei Fan, Karsten Krüger, Yu Xiao, Christian Pilat, Michael Seimetz, Robert Ringseis, Eveline Baumgart-Vogt, Klaus Eder, Norbert Weissmann, Frank-Christoph Mooren
PURPOSE: The study aimed to investigate the effects of chronic moderate exercise on regulation of intracellular calcium signaling as an important link to proliferation capacity in murine splenic T lymphocytes. METHODS: Male CD1 Swiss mice were randomly assigned either to a control group (CG) or an exercise group (EG). EG mice performed voluntary exercise for 3 months. Lymphocytes were isolated from murine spleens and intracellular calcium was determined using Fura-2(AM) and fluorescence spectrometry...
August 12, 2016: Medicine and Science in Sports and Exercise
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