scholarly journals Resonance assignment of coiled-coil 3 (CC3) domain of human STIM1

2021 ◽  
Author(s):  
Agrim Gupta ◽  
Christian Manuel Kitzler ◽  
Petr Rathner ◽  
Marc Fahrner ◽  
Herwig Grabmayr ◽  
...  
Keyword(s):  
Active Form ◽  
Coiled Coil ◽  
Divide And Conquer ◽  
Calcium Sensor ◽  
Nmr Studies ◽  
Calcium Store ◽  
Store Depletion ◽  
Store Operated Calcium Entry ◽  
Oligomeric Form ◽  
Membrane Spanning

AbstractThe protein stromal interaction molecule 1 (STIM1) plays a pivotal role in mediating store-operated calcium entry (SOCE) into cells, which is essential for adaptive immunity. It acts as a calcium sensor in the endoplasmic reticulum (ER) and extends into the cytosol, where it changes from an inactive (tight) to an active (extended) oligomeric form upon calcium store depletion. NMR studies of this protein are challenging due to its membrane-spanning and aggregation properties. Therefore follow the divide-and-conquer approach, focusing on individual domains first is in order. The cytosolic part is predicted to have a large content of coiled-coil (CC) structure. We report the 1H, 13C, 15N chemical shift assignments of the CC3 domain. This domain is crucial for the stabilisation of the tight quiescent form of STIM1 as well as for activating the ORAI calcium channel by direct contact, in the extended active form.

scholarly journals R93W mutation in Orai1 causes impaired calcium influx in platelets

Blood ◽  
2009 ◽  
Vol 113 (3) ◽  
pp. 675-678 ◽  
Author(s):  
Wolfgang Bergmeier ◽  
Masatsugu Oh-hora ◽  
Christie-Ann McCarl ◽  
R. Claire Roden ◽  
Paul F. Bray ◽  
...  
Keyword(s):  
Calcium Influx ◽  
Ex Vivo ◽  
Cellular Responses ◽  
Calcium Sensor ◽  
Flow Conditions ◽  
Calcium Store ◽  
Inactive Form ◽  
Store Operated Calcium Entry ◽  
Static Conditions

Abstract The intracellular Ca2+ concentration of many nonexcitable cells is regulated by calcium store release and store-operated calcium entry (SOCE). In platelets, STIM1 was recently identified as the main calcium sensor expressed in the endoplasmic reticulum. To evaluate the role of the SOC channel moiety, Orai1, in platelet SOCE, we generated mice expressing a mutated, inactive form of Orai1 in blood cells only (Orai1R93W). Platelets expressing Orai1R93W were characterized by markedly reduced SOCE and impaired agonist-induced increases in [Ca2+]i. Orai1R93W platelets showed reduced integrin activation and impaired degranulation when stimulated with low agonist concentrations under static conditions. This defect, however, did not significantly affect the ability of Orai1R93W platelets to aggregate or to adhere to collagen under arterial flow conditions ex vivo. In contrast, these adherent Orai1R93W platelets were defective in surface phosphatidylserine exposure, suggesting that Orai1 is crucial for the platelets' procoagulant response rather than for other Ca2+-dependent cellular responses.

Rectifying Attenuated Store-Operated Calcium Entry as a Therapeutic Approach for Alzheimer’s Disease

2021 ◽  
Vol 17 (12) ◽  
pp. 1072-1087
Author(s):  
Alexis S. Huang ◽  
Benjamin C.K. Tong ◽  
Aston J. Wu ◽  
Xiaotong Chen ◽  
Sravan G. Sreenivasmurthy ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Synaptic Plasticity ◽  
Neurodegenerative Disorder ◽  
Amyloid Plaques ◽  
Store Depletion ◽  
Store Operated Calcium Entry ◽  
Cellular Signal ◽  
Neuronal Functions ◽  
Entry Mechanism

: Alzheimer’s disease (AD) is the most common neurodegenerative disorder. Although the pathological hallmarks of AD have been identified, the derived therapies cannot effectively slow down or stop disease progression; hence, it is likely that other pathogenic mechanisms are involved in AD pathogenesis. Intracellular calcium (Ca2+) dyshomeostasis has been consistently observed in AD patients and numerous AD models and may emerge prior to the development of amyloid plaques and neurofibrillary tangles. Thus, intracellular Ca2+ disruptions are believed to play an important role in AD development and could serve as promising therapeutic intervention targets. : One of the disrupted intracellular Ca2+ signaling pathways manifested in AD is attenuated storeoperated Ca2+ entry (SOCE). SOCE is an extracellular Ca2+ entry mechanism mainly triggered by intracellular Ca2+ store depletion. Maintaining normal SOCE function not only provides a means for the cell to replenish ER Ca2+ stores but also serves as a cellular signal that maintains normal neuronal functions, including excitability, neurogenesis, neurotransmission, synaptic plasticity, and gene expression. However, normal SOCE function is diminished in AD, resulting in disrupted neuronal spine stability and synaptic plasticity and the promotion of amyloidogenesis. Mounting evidence suggests that rectifying diminished SOCE in neurons may intervene with the progression of AD. In this review, the mechanisms of SOCE disruption and the associated pathogenic impacts on AD will be discussed. We will also highlight the potential therapeutic targets or approaches that may help ameliorate SOCE deficits for AD treatment.

scholarly journals Orai1 regulates intracellular calcium, arrest, and shape polarization during neutrophil recruitment in shear flow

Blood ◽  
2010 ◽  
Vol 115 (3) ◽  
pp. 657-666 ◽  
Author(s):  
Ulrich Y. Schaff ◽  
Neha Dixit ◽  
Emily Procyk ◽  
Itsukyo Yamayoshi ◽  
Tiffany Tse ◽  
...  
Keyword(s):  
Shear Flow ◽  
Calcium Entry ◽  
Calcium Store ◽  
Immune Synapse ◽  
Acute Response ◽  
Formyl Peptide ◽  
Store Operated Calcium Entry ◽  
Cell Arrest ◽  
And Migration ◽  
Sirna Knockdown

Abstract Orai1 was reported to function as a calcium channel subunit that facilitates store operated calcium entry (SOCE) in T cells and is necessary for formation of the immune synapse. We reasoned that SOCE via Orai1 might regulate PMNs activation during recruitment to inflamed endothelium. Orai1 function was assessed by real-time imaging of calcium transients as PMNs were stimulated to roll, arrest, and migrate on E-selectin and ICAM-1 in shear flow. Calcium entry was significantly reduced when Orai1 function was impaired by heterozygous knockout in a mouse model or by siRNA knockdown in HL-60 cells. Reduced Orai-1 expression correlated with the delayed onset of arrest and reduced ability to transition to a polarized migratory phenotype. Inhibition of SOCE by treatment with 2-APB, or blocking phospholipase C (PLC) mediated calcium store release with U73122, abrogated formyl peptide induced calcium elevation, and delayed subsequent cell arrest and polarization. These results suggest that calcium entry via Orai1 is the predominant SOCE that cooperates with cytoplasmic calcium store release in coordinating integrin-dependent PMN arrest and migration in the acute response to inflammation.

scholarly journals Evidence for an interaction between Golli and STIM1 in store-operated calcium entry

2010 ◽  
Vol 430 (3) ◽  
pp. 453-460 ◽  
Author(s):  
Ciara M. Walsh ◽  
Mary K. Doherty ◽  
Alexei V. Tepikin ◽  
Robert D. Burgoyne
Keyword(s):  
Hela Cells ◽  
Underlying Mechanism ◽  
Binding Assays ◽  
Cellular Functions ◽  
Store Depletion ◽  
Store Operated Calcium Entry ◽  
Oligodendrocyte Precursor ◽  
Ca2 Channels

SOCCs (store-operated Ca2+ channels) are highly selective ion channels that are activated upon release of Ca2+ from intracellular stores to regulate a multitude of diverse cellular functions. It was reported previously that Golli-BG21, a member of the MBP (myelin basic protein) family of proteins, regulates SOCE (store-operated Ca2+ entry) in T-cells and oligodendrocyte precursor cells, but the underlying mechanism for this regulation is unknown. In the present study we have discovered that Golli can directly interact with the ER (endoplasmic reticulum) Ca2+-sensing protein STIM1 (stromal interaction molecule 1). Golli interacts with the C-terminal domain of STIM1 in both in vitro and in vivo binding assays and this interaction may be modulated by the intracellular Ca2+ concentration. Golli also co-localizes with full-length STIM1 and Orai1 complexes in HeLa cells following Ca2+ store depletion. Overexpression of Golli reduces SOCE in HeLa cells, but this inhibition is overcome by overexpressing STIM1. We therefore suggest that Golli binds to STIM1–Orai1 complexes to negatively regulate the activity of SOCCs.

scholarly journals Pex17p of Saccharomyces cerevisiae Is a Novel Peroxin and Component of the Peroxisomal Protein Translocation Machinery

1998 ◽  
Vol 140 (1) ◽  
pp. 49-60 ◽  
Author(s):  
Bettina Huhse ◽  
Peter Rehling ◽  
Markus Albertini ◽  
Lars Blank ◽  
Karl Meller ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Protein Translocation ◽  
Coiled Coil ◽  
Matrix Proteins ◽  
Peroxisomal Membrane ◽  
Trimeric Complex ◽  
Peroxisomal Targeting ◽  
Targeting Signal ◽  
Membrane Spanning ◽  
Mutant Cells

The Saccharomyces cerevisiae pex17-1 mutant was isolated from a screen to identify mutants defective in peroxisome biogenesis. pex17-1 and pex17 null mutants fail to import matrix proteins into peroxisomes via both PTS1- and PTS2-dependent pathways. The PEX17 gene (formerly PAS9; Albertini, M., P. Rehling, R. Erdmann, W. Girzalsky, J.A.K.W. Kiel, M. Veenhuis, and W.-H Kunau. 1997. Cell. 89:83–92) encodes a polypeptide of 199 amino acids with one predicted membrane spanning region and two putative coiled-coil structures. However, localization studies demonstrate that Pex17p is a peripheral membrane protein located at the surface of peroxisomes. Particulate structures containing the peroxisomal integral membrane proteins Pex3p and Pex11p are evident in pex17 mutant cells, indicating the existence of peroxisomal remnants (“ghosts”). This finding suggests that pex17 null mutant cells are not impaired in peroxisomal membrane biogenesis. Two-hybrid studies showed that Pex17p directly binds to Pex14p, the recently proposed point of convergence for the two peroxisomal targeting signal (PTS)-dependent import pathways, and indirectly to Pex5p, the PTS1 receptor. The latter interaction requires Pex14p, indicating the potential of these three peroxins to form a trimeric complex. This conclusion is supported by immunoprecipitation experiments showing that Pex14p and Pex17p coprecipitate with both PTS receptors in the absence of Pex13p. From these and other studies we conclude that Pex17p, in addition to Pex13p and Pex14p, is the third identified component of the peroxisomal translocation machinery.

scholarly journals Role of phosphoinositides in STIM1 dynamics and store-operated calcium entry

2009 ◽  
Vol 425 (1) ◽  
pp. 159-168 ◽  
Author(s):  
Ciara M. Walsh ◽  
Michael Chvanov ◽  
Lee P. Haynes ◽  
Ole H. Petersen ◽  
Alexei V. Tepikin ◽  
...  
Keyword(s):  
Fluorescent Protein ◽  
Yellow Fluorescent Protein ◽  
Phosphatidylinositol 3 Kinase ◽  
Enhanced Yellow Fluorescent Protein ◽  
Store Depletion ◽  
Store Operated Calcium Entry ◽  
Translocation Mechanism ◽  
Direct Binding ◽  
Phosphatidylinositol 4

Ca2+ entry through store-operated Ca2+ channels involves the interaction at ER–PM (endoplasmic reticulum–plasma membrane) junctions of STIM (stromal interaction molecule) and Orai. STIM proteins are sensors of the luminal ER Ca2+ concentration and, following depletion of ER Ca2+, they oligomerize and translocate to ER–PM junctions where they form STIM puncta. Direct binding to Orai proteins activates their Ca2+ channel function. It has been suggested that an additional interaction of the C-terminal polybasic domain of STIM1 with PM phosphoinositides could contribute to STIM1 puncta formation prior to binding to Orai. In the present study, we investigated the role of phosphoinositides in the formation of STIM1 puncta and SOCE (store-operated Ca2+ entry) in response to store depletion. Treatment of HeLa cells with inhibitors of PI3K (phosphatidylinositol 3-kinase) and PI4K (phosphatidylinositol 4-kinase) (wortmannin and LY294002) partially inhibited formation of STIM1 puncta. Additional rapid depletion of PtdIns(4,5)P2 resulted in more substantial inhibition of the translocation of STIM1–EYFP (enhanced yellow fluorescent protein) into puncta. The inhibition was extensive at a concentration of LY294002 (50 μM) that should primarily inhibit PI3K, consistent with a major role for PtdIns(4,5)P2 and PtdIns(3,4,5)P3 in puncta formation. Depletion of phosphoinositides also inhibited SOCE based on measurement of the rise in intracellular Ca2+ concentration after store depletion. Overexpression of Orai1 resulted in a recovery of translocation of STMI1 into puncta following phosphoinositide depletion and, under these conditions, SOCE was increased to above control levels. These observations support the idea that phosphoinositides are not essential but contribute to STIM1 accumulation at ER–PM junctions with a second translocation mechanism involving direct STIM1–Orai interactions.

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