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Shalygin A, Kolesnikov D, Glushankova L, Gusev K, Skopin A, Skobeleva K, Kaznacheyeva EV. Role of STIM2 and Orai proteins in regulating TRPC1 channel activity upon calcium store depletion. Cell Calcium 2021; 97:102432. [PMID: 34157631 DOI: 10.1016/j.ceca.2021.102432] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2020] [Revised: 05/08/2021] [Accepted: 06/04/2021] [Indexed: 11/17/2022]
Abstract
Store-operated calcium channels are the major player in calcium signaling in non-excitable cells. Store-operated calcium entry is associated with the Orai, stromal interaction molecule (STIM), and transient receptor potential canonical (TRPC) protein families. Researchers have provided conflicting data about TRPC1 channel regulation by Orai and STIM. To determine how Orai and STIM influence endogenous TRPC1 pore properties and regulation, we used single channel patch-clamp recordings. Here we showed that knockout or knockdown of Orai1 or Orai3 or overexpression of the dominant-negative mutant Orai1 E106Q did not change the conductance or selectivity of single TRPC1 channels. In addition, these TRPC1 channel properties did not depend on the amount of STIM1 and STIM2 proteins. To study STIM2-mediated regulation of TRPC1 channels, we utilized partial calcium store depletion induced by application of 10 nM thapsigargin (Tg). TRPC1 activation by endogenous STIM2 was greatly decreased in acute extracellular calcium-free experiments. STIM2 overexpression increased both the basal activity and number of silent TRPC1 channels in the plasma membrane. After calcium store depletion, overexpressed STIM2 directly activated TRPC1 in the plasma membrane even without calcium entry in acute experiments. However, this effect was abrogated by co-expression with the non-permeable Orai1 E106Q mutant protein. Taken together, our single-channel patch clamp experiments clearly demonstrated that endogenous TRPC1 forms a channel pore without involving Orai proteins. Calcium entry through Orai triggered TRPC1 channel activation in the plasma membrane, while subsequent STIM2-mediated TRPC1 activity regulation was not dependent on calcium entry.
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Affiliation(s)
- A Shalygin
- Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretsky Avenue, St. Petersburg 194064, Russia.
| | - D Kolesnikov
- Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretsky Avenue, St. Petersburg 194064, Russia
| | - L Glushankova
- Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretsky Avenue, St. Petersburg 194064, Russia
| | - K Gusev
- Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretsky Avenue, St. Petersburg 194064, Russia
| | - A Skopin
- Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretsky Avenue, St. Petersburg 194064, Russia
| | - K Skobeleva
- Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretsky Avenue, St. Petersburg 194064, Russia
| | - E V Kaznacheyeva
- Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretsky Avenue, St. Petersburg 194064, Russia.
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Berlansky S, Humer C, Sallinger M, Frischauf I. More Than Just Simple Interaction between STIM and Orai Proteins: CRAC Channel Function Enabled by a Network of Interactions with Regulatory Proteins. Int J Mol Sci 2021; 22:E471. [PMID: 33466526 PMCID: PMC7796502 DOI: 10.3390/ijms22010471] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Revised: 12/29/2020] [Accepted: 12/29/2020] [Indexed: 12/27/2022] Open
Abstract
The calcium-release-activated calcium (CRAC) channel, activated by the release of Ca2+ from the endoplasmic reticulum (ER), is critical for Ca2+ homeostasis and active signal transduction in a plethora of cell types. Spurred by the long-sought decryption of the molecular nature of the CRAC channel, considerable scientific effort has been devoted to gaining insights into functional and structural mechanisms underlying this signalling cascade. Key players in CRAC channel function are the Stromal interaction molecule 1 (STIM1) and Orai1. STIM1 proteins span through the membrane of the ER, are competent in sensing luminal Ca2+ concentration, and in turn, are responsible for relaying the signal of Ca2+ store-depletion to pore-forming Orai1 proteins in the plasma membrane. A direct interaction of STIM1 and Orai1 allows for the re-entry of Ca2+ from the extracellular space. Although much is already known about the structure, function, and interaction of STIM1 and Orai1, there is growing evidence that CRAC under physiological conditions is dependent on additional proteins to function properly. Several auxiliary proteins have been shown to regulate CRAC channel activity by means of direct interactions with STIM1 and/or Orai1, promoting or hindering Ca2+ influx in a mechanistically diverse manner. Various proteins have also been identified to exert a modulatory role on the CRAC signalling cascade although inherently lacking an affinity for both STIM1 and Orai1. Apart from ubiquitously expressed representatives, a subset of such regulatory mechanisms seems to allow for a cell-type-specific control of CRAC channel function, considering the rather restricted expression patterns of the specific proteins. Given the high functional and clinical relevance of both generic and cell-type-specific interacting networks, the following review shall provide a comprehensive summary of regulators of the multilayered CRAC channel signalling cascade. It also includes proteins expressed in a narrow spectrum of cells and tissues that are often disregarded in other reviews of similar topics.
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Affiliation(s)
| | | | | | - Irene Frischauf
- Institute of Biophysics, Johannes Kepler University, 4020 Linz, Austria; (S.B.); (C.H.); (M.S.)
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Shalygin AV, Ryazantseva MA, Glushankova LN, Gusev KO, Kolesnikov DO, Vigont VA, Skopin AY, Skobeleva KV, Kaznacheeva EV. Homer 1a Induces Calcium Channel Activation, but Does Not Change Their Properties in A431 Cells. Bull Exp Biol Med 2018; 165:272-275. [PMID: 29923011 DOI: 10.1007/s10517-018-4146-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2017] [Indexed: 11/25/2022]
Abstract
Store-operated channels activated in response to intracellular calcium store depletion represent the main pathway of calcium entry from the extracellular space in nonelectroexcitable cells. Adapter proteins organize the components of this system into integral complex. We studied the influence of adapter proteins of the Homer family on endogenous store-operated calcium Imin channels in A431 cells. Monomeric Homer 1a proteins increase activity of Imin channels, but did not modulate their electrophysiological properties. Recombinant Homer 1c protein did not block the induced calcium currents.
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Affiliation(s)
- A V Shalygin
- Laboratory of Cell Membrane Ionic Channels, Institute of Cytology of Russian Academy of Sciences, St. Petersburg, Russia.
| | - M A Ryazantseva
- Laboratory of Cell Membrane Ionic Channels, Institute of Cytology of Russian Academy of Sciences, St. Petersburg, Russia
| | - L N Glushankova
- Laboratory of Cell Membrane Ionic Channels, Institute of Cytology of Russian Academy of Sciences, St. Petersburg, Russia
| | - K O Gusev
- Laboratory of Cell Membrane Ionic Channels, Institute of Cytology of Russian Academy of Sciences, St. Petersburg, Russia
| | - D O Kolesnikov
- Laboratory of Cell Membrane Ionic Channels, Institute of Cytology of Russian Academy of Sciences, St. Petersburg, Russia
| | - V A Vigont
- Laboratory of Cell Membrane Ionic Channels, Institute of Cytology of Russian Academy of Sciences, St. Petersburg, Russia
| | - A Yu Skopin
- Laboratory of Cell Membrane Ionic Channels, Institute of Cytology of Russian Academy of Sciences, St. Petersburg, Russia
| | - K V Skobeleva
- Laboratory of Cell Membrane Ionic Channels, Institute of Cytology of Russian Academy of Sciences, St. Petersburg, Russia
| | - E V Kaznacheeva
- Laboratory of Cell Membrane Ionic Channels, Institute of Cytology of Russian Academy of Sciences, St. Petersburg, Russia
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Electrophysiological Features of Single Store-Operated Calcium Channels in HEK S4 Cell Line with Stable STIM1 Protein Knockdown. Bull Exp Biol Med 2017; 163:326-329. [PMID: 28744649 DOI: 10.1007/s10517-017-3795-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Indexed: 01/21/2023]
Abstract
An important role in intracellular calcium signaling is played by store-operated channels activated by STIM proteins, calcium sensors of the endoplasmic reticulum. In stable STIM1 knockdown HEK S4 cells, single channels activated by depletion of intracellular calcium stores were detected by cell-attached patch-clamp technique and their electrophysiological parameters were described. Comparison of the properties of single channels in HEK293 and HEK S4 cells revealed no significant differences in their current-voltage curves, while regulation of store-operated calcium channels in these cell lines depended on the level of STIM1 expression. We can conclude that electrophysiological peculiarities of store-regulated calcium entry observed in different cells can be explained by differences in STIM1 expression.
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Shalygin A, Skopin A, Kalinina V, Zimina O, Glushankova L, Mozhayeva GN, Kaznacheyeva E. STIM1 and STIM2 proteins differently regulate endogenous store-operated channels in HEK293 cells. J Biol Chem 2014; 290:4717-4727. [PMID: 25533457 DOI: 10.1074/jbc.m114.601856] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The endoplasmic reticulum calcium sensors stromal interaction molecules 1 and 2 (STIM1 and STIM2) are key modulators of store-operated calcium entry. Both these sensors play a major role in physiological functions in normal tissue and in pathology, but available data on native STIM2-regulated plasma membrane channels are scarce. Only a few studies have recorded STIM2-induced CRAC (calcium release-activated calcium) currents. On the other hand, many cell types display store-operated currents different from CRAC. The STIM1 protein regulates not only CRAC but also transient receptor potential canonical (TRPC) channels, but it has remained unclear whether STIM2 is capable of regulating store-operated non-CRAC channels. Here we present for the first time experimental evidence for the existence of endogenous non-CRAC STIM2-regulated channels. As shown in single-channel patch clamp experiments on HEK293 cells, selective activation of native STIM2 proteins or STIM2 overexpression results in store-operated activation of Imin channels, whereas STIM1 activation blocks this process. Changes in the ratio between active STIM2 and STIM1 proteins can switch the regulation of Imin channels between store-operated and store-independent modes. We have previously characterized electrophysiological properties of different Ca(2+) influx channels coexisting in HEK293 cells. The results of this study show that STIM1 and STIM2 differ in the ability to activate these store-operated channels; Imin channels are regulated by STIM2, TRPC3-containing INS channels are induced by STIM1, and TRPC1-composed Imax channels are activated by both STIM1 and STIM2. These new data about cross-talk between STIM1 and STIM2 and their different roles in store-operated channel activation are indicative of an additional level in the regulation of store-operated calcium entry pathways.
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Affiliation(s)
- Alexey Shalygin
- From the Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretsky Avenue, St. Petersburg 194064, Russia.
| | - Anton Skopin
- From the Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretsky Avenue, St. Petersburg 194064, Russia
| | - Vera Kalinina
- From the Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretsky Avenue, St. Petersburg 194064, Russia
| | - Olga Zimina
- From the Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretsky Avenue, St. Petersburg 194064, Russia
| | - Lyuba Glushankova
- From the Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretsky Avenue, St. Petersburg 194064, Russia
| | - Galina N Mozhayeva
- From the Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretsky Avenue, St. Petersburg 194064, Russia
| | - Elena Kaznacheyeva
- From the Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretsky Avenue, St. Petersburg 194064, Russia.
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TRPC1 protein forms only one type of native store-operated channels in HEK293 cells. Biochimie 2012; 95:347-53. [PMID: 23079337 DOI: 10.1016/j.biochi.2012.10.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2012] [Accepted: 10/05/2012] [Indexed: 11/23/2022]
Abstract
TRPC1 is a major component of store-operated calcium entry in many cell types. In our previous studies, three types of endogenous store-operated calcium channels have been described in HEK293 cells, but it remained unknown which of these channels are composed of TRPC1 proteins. Here, this issue has been addressed by performing single-channel analysis in HEK293 cells transfected with anti-TRPC1 siRNA (siTPRC1) or a TPRC1-encoding plasmid. The results show that thapsigargin-or agonist-induced calcium influx is significantly attenuated in siTRPC1-transfected HEK293 cells. TRPC1 knockdown by siRNA results in the disappearance of store-operated I(max) channels, while the properties of I(min) and I(NS) channels are unaffected. In HEK293 cells with overexpressed TRPC1 protein, the unitary current-voltage relationship of exogenous TRPC1 channels is almost linear, with a slope conductance of about 17 pS. The extrapolated reversal potential of expressed TRPC1 channels is +30 mV. Therefore, the main electrophysiological and regulatory properties of expressed TRPC1 and native I(max) channels are identical. Moreover, TRPC1 overexpression in HEK293 cells results in an increased number of store-operated I(max) channels. All these data allow us to conclude that TRPC1 protein forms native store-operated I(max) channels but is not an essential subunit for other store-operated channel types in HEK293 cells.
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Shalygin AV, Ryazantseva MA, Glushankova LN, Bezprozvanny IB, Mozhayeva GN, Kaznacheyeva EV. Delay in I(min) channel activation induced by dissociation of Homer proteins in A431 cells. DOKLADY BIOLOGICAL SCIENCES : PROCEEDINGS OF THE ACADEMY OF SCIENCES OF THE USSR, BIOLOGICAL SCIENCES SECTIONS 2011; 438:131-4. [PMID: 21728119 DOI: 10.1134/s0012496611030033] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2010] [Indexed: 11/22/2022]
Affiliation(s)
- A V Shalygin
- Institute of Cytology, Russian Academy of Sciences, Tikhoretskii pr. 4, St. Petersburg, 194064, Russia
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