ORAI channels are critical for receptor-mediated endocytosis of albumin

Zeng, Bo; Chen, Gui Lan; Garcia-Vaz, Eliana; Bhandari, Sunil; Daskoulidou, Nikoleta; Berglund, Lisa; Jiang, Huai; Hallett, Thomas; Zhou, Lu Ping; Lei, Huang; Xu, Zi Hao; Nair, Viji; Nelson, Robert G.; Ju, Wenjun; Kretzler, Matthias; Atkin, Stephen L.; Gomez, Maria F.; Xu, Shan

doi:10.1038/s41467-017-02094-y

Cited by 44 publications

(47 citation statements)

References 51 publications

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“…To identify the pathway of Ca 2+ influx activated by subsequent application of 2.5 mM extracellular Ca 2+ after store depletion, we investigated the effects of CRAC channel inhibitors, synta66 ( Beech, 2012 ; Kruchten et al, 2012 ; Derler et al, 2013 ; Molnár et al, 2016 ) and BTP2 ( Ishikawa et al, 2003 ; Zitt et al, 2004 ; Zeng et al, 2017 ), on the Ca 2+ influx. After store depletion by pretreatment of 10 μM TG in the absence of extracellular Ca 2+ , application of 2.5 mM extracellular Ca 2+ increased [Ca 2+ ] i to a peak value of 1.32 ± 0.04 F / F 0 units ( N = 9).…”

Section: Resultsmentioning

confidence: 99%

High pH-Sensitive Store-Operated Ca2+ Entry Mediated by Ca2+ Release-Activated Ca2+ Channels in Rat Odontoblasts

et al. 2018

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Odontoblasts play a crucial role in dentin formation and sensory transduction following the application of stimuli to the dentin surface. Various exogenous and endogenous stimuli elicit an increase in the intracellular free calcium concentration ([Ca2+]i) in odontoblasts, which is mediated by Ca2+ release from intracellular Ca2+ stores and/or Ca2+ influx from the extracellular medium. In a previous study, we demonstrated that the depletion of Ca2+ stores in odontoblasts activated store-operated Ca2+ entry (SOCE), a Ca2+ influx pathway. However, the precise biophysical and pharmacological properties of SOCE in odontoblasts have remained unclear. In the present study, we examined the functional expression and pharmacological properties of Ca2+ release-activated Ca2+ (CRAC) channels that mediate SOCE and evaluated the alkali sensitivity of SOCE in rat odontoblasts. In the absence of extracellular Ca2+, treatment with thapsigargin (TG), a sarco/endoplasmic reticulum Ca2+-ATPase inhibitor, induced an increase in [Ca2+]i. After [Ca2+]i returned to near-resting levels, the subsequent application of 2.5 mM extracellular Ca2+ resulted in an increase in [Ca2+]i which is a typical of SOCE activation. Additionally, application of 2-methylthioadenosine diphosphate trisodium salt (2-MeSADP), a P2Y1,12,13 receptor agonist, or carbachol (CCh), a muscarinic cholinergic receptor agonist, in the absence of extracellular Ca2+, induced a transient increase in [Ca2+]i. The subsequent addition of extracellular Ca2+ resulted in significantly higher [Ca2+]i in 2-MeSADP- or CCh-treated odontoblasts than in untreated cells. SOCE, that is activated by addition of extracellular Ca2+ in the TG pretreated odontoblasts was then suppressed by Synta66, BTP2, or lanthanum, which are CRAC channel inhibitors. Treatment with an alkaline solution enhanced SOCE, while treatment with HC030031, a TRPA1 channel antagonist, inhibited it. The amplitude of SOCE at pH 9 in the presence of HC030031 was higher than that at pH 7.4 in the absence of HC030031. These findings indicate that CRAC channel-mediated alkali-sensitive SOCE occurs in odontoblasts. SOCE is mediated by P2Y and muscarinic-cholinergic receptors, which are activated by endogenous ligands in odontoblasts.

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Section: Resultsmentioning

confidence: 99%

High pH-Sensitive Store-Operated Ca2+ Entry Mediated by Ca2+ Release-Activated Ca2+ Channels in Rat Odontoblasts

et al. 2018

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“…These localized ER structures also express early endosome markers such as Rab5 and EEA1 43 , but are not recognized by the N-terminal STIM1 antibod-ies; therefore, these domains likely contain the alt1-Stim1A splice combination. Whether a permanent association with these Stim1 variants and Orai in the PM is required for endocytosis and is related to the finding that Orai channels are critical for receptor-mediated endocytosis of albumin in also in proximal tubular epithelial cells 44 requires further investigation and generation of splice-specific knock-out models. What also remains unclear is how the dramatic remodeling and various assemblies at these specializations are kept in a dynamic equilibrium and how they are regulated.…”

Section: Discussionmentioning

confidence: 99%

Alternative splicing switches STIM1 targeting to specialized membrane contact sites and modifies SOCE

Knapp

Förderer

Alansary

et al. 2020

Preprint

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Alternative splicing is a potent modifier of protein function. Stromal interaction molecule 1 (Stim1) is the essential activator molecule of store-operated Ca 2+ entry (SOCE) and a sorting regulator of certain ER proteins such as Stimulator of interferon genes (STING). Here, we characterize a conserved new variant, Stim1A, where splice-insertion translates into an additional C-terminal domain. We find prominent expression of exonA mRNA in testes, astrocytes, kidney and heart and confirm Stim1A protein in Western blot of testes. In situ, endogenous Stim1 with domain A, but not Stim1 without domain A localizes to unique adhesion junctions and to specialized membrane retrieval sites (tubulobulbar complexes) in testes. Functionally, using Ca 2+ imaging and patch-clamp analysis, Stim1A shows a dominant-negative effect on SOCE and I CRAC , despite normal clustering and interaction with Orai1 investigated by combined TIRF and FRET analyses and as confirmed by an increased SOCE upon knock-down of endogenous Stim1A in astrocytes. Mutational analyses in conjunction with imaging and patch-clamp analyses of residues either in domain A or within the N-terminal region of Orai1 demonstrate a specific defect in stabilized channel gating. Our findings demonstrate that celltype specific splicing of STIM1 adds both an intracellular targeting switch and adapts SOCE to meet the Ca 2+ requirements of specific subcellular contact sites. splicing | CRAC | membrane | endocytosis | gating | Sertoli | Orai | calcium | trafficking | variantCorrespondence: barbara.niemeyer@uks.eu

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“…Orai1 tagged with a fluorescent protein such as GFP has been overexpressed have shown that Orai1 is principally located at or near the PM [1,11,12,16]. However, the results of several other studies provide evidence for the internalisation of Orai1 to endosomes, cycling and trafficking of Orai1 between the PM and intracellular organelles, and the location of Orai in acidic organelles including secretory granules [43][44][45][62][63][64][65][66]. It is also interesting to note that the distribution of Orai1 amongst the liver subcellular fractions is quite different from that of TRPM2.…”

Section: Discussionmentioning

confidence: 99%

Evidence for the interaction of peroxiredoxin-4 with the store-operated calcium channel activator STIM1 in liver cells

et al. 2018

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Ca entry through store-operated Ca channels (SOCs) in the plasma membrane (PM) of hepatocytes plays a central role in the hormonal regulation of liver metabolism. SOCs are composed of Orai1, the channel pore protein, and STIM1, the activator protein, and are regulated by hormones and reactive oxygen species (ROS). In addition to Orai1, STIM1 also interacts with several other intracellular proteins. Most previous studies of the cellular functions of Orai1 and STIM1 have employed immortalised cells in culture expressing ectopic proteins tagged with a fluorescent polypeptide such as GFP. Little is known about the intracellular distributions of endogenous Orai1 and STIM1. The aims are to determine the intracellular distribution of endogenous Orai1 and STIM1 in hepatocytes and to identify novel STIM1 binding proteins. Subcellular fractions of rat liver were prepared by homogenisation and differential centrifugation. Orai1 and STIM1 were identified and quantified by western blot. Orai1 was found in the PM (0.03%), heavy (44%) and light (27%) microsomal fractions, and STIM1 in the PM (0.09%), and heavy (85%) and light (13%) microsomal fractions. Immunoprecipitation of STIM1 followed by LC/MS or western blot identified peroxiredoxin-4 (Prx-4) as a potential STIM1 binding protein. Prx-4 was found principally in the heavy microsomal fraction. Knockdown of Prx-4 using siRNA, or inhibition of Prx-4 using conoidin A, did not affect Ca entry through SOCs but rendered SOCs susceptible to inhibition by HO. It is concluded that, in hepatocytes, a considerable proportion of endogenous Orai1 and STIM1 is located in the rough ER. In the rough ER, STIM1 interacts with Prx-4, and this interaction may contribute to the regulation by ROS of STIM1 and SOCs.

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ORAI channels are critical for receptor-mediated endocytosis of albumin

Cited by 44 publications

References 51 publications

High pH-Sensitive Store-Operated Ca2+ Entry Mediated by Ca2+ Release-Activated Ca2+ Channels in Rat Odontoblasts

High pH-Sensitive Store-Operated Ca2+ Entry Mediated by Ca2+ Release-Activated Ca2+ Channels in Rat Odontoblasts

Alternative splicing switches STIM1 targeting to specialized membrane contact sites and modifies SOCE

Evidence for the interaction of peroxiredoxin-4 with the store-operated calcium channel activator STIM1 in liver cells

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