Regulation of endogenous and heterologous Ca²⁺ release-activated Ca²⁺ currents by pH.

Beck, Andreas; Fleig, Andrea; Penner, Reinhold; Peinelt, Christine (2014). Regulation of endogenous and heterologous Ca²⁺ release-activated Ca²⁺ currents by pH. Cell calcium, 56(3), pp. 235-243. Elsevier 10.1016/j.ceca.2014.07.011

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Deviations from physiological pH (∼pH 7.2) as well as altered Ca(2+) signaling play important roles in immune disease and cancer. One of the most ubiquitous pathways for cellular Ca(2+) influx is the store-operated Ca(2+) entry (SOCE) or Ca(2+) release-activated Ca(2+) current (ICRAC), which is activated upon depletion of intracellular Ca(2+) stores. We here show that extracellular and intracellular changes in pH regulate both endogenous ICRAC in Jurkat T lymphocytes and RBL2H3 cells, and heterologous ICRAC in HEK293 cells expressing the molecular components STIM1/2 and Orai1/2/3 (CRACM1/2/3). We find that external acidification suppresses, and alkalization facilitates IP3-induced ICRAC. In the absence of IP3, external alkalization did not elicit endogenous ICRAC but was able to activate heterologous ICRAC in HEK293 cells expressing Orai1/2/3 and STIM1 or STIM2. Similarly, internal acidification reduced IP3-induced activation of endogenous and heterologous ICRAC, while alkalization accelerated its activation kinetics without affecting overall current amplitudes. Mutation of two aspartate residues to uncharged alanine amino acids (D110/112A) in the first extracellular loop of Orai1 significantly attenuated both the inhibition of ICRAC by external acidic pH as well as its facilitation by alkaline conditions. We conclude that intra- and extracellular pH differentially regulates ICRAC. While intracellular pH might affect aggregation and/or binding of STIM to Orai, external pH seems to modulate ICRAC through its channel pore, which in Orai1 is partially mediated by residues D110 and D112.

Item Type:

Journal Article (Original Article)

Division/Institute:

04 Faculty of Medicine > Pre-clinic Human Medicine > Institute of Biochemistry and Molecular Medicine

UniBE Contributor:

Peinelt, Christine

Subjects:

500 Science > 570 Life sciences; biology
600 Technology > 610 Medicine & health

ISSN:

0143-4160

Publisher:

Elsevier

Language:

English

Submitter:

Christine Peinelt

Date Deposited:

18 Jun 2018 15:32

Last Modified:

19 Jun 2018 09:14

Publisher DOI:

10.1016/j.ceca.2014.07.011

PubMed ID:

25168908

Uncontrolled Keywords:

HEK293 I(CRAC) Jurkat cells Orai RBL STIM Whole-cell patch clamp

BORIS DOI:

10.7892/boris.97450

URI:

https://boris.unibe.ch/id/eprint/97450

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