Dataset Information

MicroRNA-150 modulates intracellular Ca 2+ levels in naive CD8+ T cells by targeting TMEM20.

ABSTRACT: Regulation of intracellular Ca2+ signaling is a major determinant of CD8+ T cell responsiveness, but the mechanisms underlying this regulation of Ca2+ levels, especially in naïve CD8+ T cells, are not fully defined. Here, we showed that microRNA-150 (miR-150) controls intracellular Ca2+ levels in naïve CD8+ T cells required for activation by suppressing TMEM20, a negative regulator of Ca2+ extrusion. miR-150 deficiency increased TMEM20 expression, which resulted in increased intracellular Ca2+ levels in naïve CD8+ T cells. The subsequent increase in Ca2+ levels induced expression of anergy-inducing genes, such as Cbl-b, Egr2, and p27, through activation of NFAT1, as well as reduced cell proliferation, cytokine production, and the antitumor activity of CD8+ T cells upon antigenic stimulation. The anergy-promoting molecular milieu and function induced by miR-150 deficiency were rescued by reinstatement of miR-150. Additionally, knockdown of TMEM20 in miR-150-deficient naïve CD8+ T cells reduced intracellular Ca2+ levels. Our findings revealed that miR-150 play essential roles in controlling intracellular Ca2+ level and activation in naïve CD8+ T cells, which suggest a mechanism to overcome anergy induction by the regulation of intracellular Ca2+ levels.

SUBMITTER: Kim TD

PROVIDER: S-EPMC5453935 | biostudies-literature | 2017 Jun

REPOSITORIES: biostudies-literature

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MicroRNA-150 modulates intracellular Ca 2+ levels in naïve CD8+ T cells by targeting TMEM20.

Kim Tae-Don TD Jung Hong-Ryul HR Seo Sang-Hwan SH Oh Se-Chan SC Ban Youngho Y Tan Xiaoxia X Min Kim Jung J Hyun Lee Sang S Koh Duk-Su DS Jung Haiyoung H Park Young-Jun YJ Ran Yoon Suk S Doh Junsang J Ha Sang-Jun SJ Choi Inpyo I Greenberg Philip D PD

Scientific reports 20170601 1

Regulation of intracellular Ca2+ signaling is a major determinant of CD8+ T cell responsiveness, but the mechanisms underlying this regulation of Ca2+ levels, especially in naïve CD8+ T cells, are not fully defined. Here, we showed that microRNA-150 (miR-150) controls intracellular Ca2+ levels in naïve CD8+ T cells required for activation by suppressing TMEM20, a negative regulator of Ca2+ extrusion. miR-150 deficiency ...[more]

PMID: 28572627

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Project description:Mitochondrial Ca2+ handling is accomplished by balancing Ca2+ uptake, primarily via the Ru360-sensitive mitochondrial calcium uniporter (MCU), Ca2+ buffering in the matrix and Ca2+ efflux mainly via Ca2+ ion exchangers, such as the Na+/Ca2+ exchanger (NCLX) and the Ca2+/H+ exchanger (CHE). The mechanism of CHE in cardiac mitochondria is not well-understood and its contribution to matrix Ca2+ regulation is thought to be negligible, despite higher expression of the putative CHE protein, LETM1, compared to hepatic mitochondria. In this study, Ca2+ efflux via the CHE was investigated in isolated rat cardiac mitochondria and permeabilized H9c2 cells. Mitochondria were exposed to (a) increasing matrix Ca2+ load via repetitive application of a finite CaCl2 bolus to the external medium and (b) change in the pH gradient across the inner mitochondrial membrane (IMM). Ca2+ efflux at different matrix Ca2+ loads was revealed by inhibiting Ca2+ uptake or reuptake with Ru360 after increasing number of CaCl2 boluses. In Na+-free experimental buffer and with Ca2+ uptake inhibited, the rate of Ca2+ efflux and steady-state free matrix Ca2+ [mCa2+]ss increased as the number of administered CaCl2 boluses increased. ADP and cyclosporine A (CsA), which are known to increase Ca2+ buffering while maintaining a constant [mCa2+]ss, decreased the rate of Ca2+ efflux via the CHE, with a significantly greater decrease in the presence of ADP. ADP also increased Ca2+ buffering rate and decreased [mCa2+]ss. A change in the pH of the external medium to a more acidic value from 7.15 to 6.8∼6.9 caused a twofold increase in the Ca2+ efflux rate, while an alkaline change in pH from 7.15 to 7.4∼7.5 did not change the Ca2+ efflux rate. In addition, CHE activation was associated with membrane depolarization. Targeted transient knockdown of LETM1 in permeabilized H9c2 cells modulated Ca2+ efflux. The results indicate that Ca2+ efflux via the CHE in cardiac mitochondria is modulated by acidic buffer pH and by total matrix Ca2+. A mechanism is proposed whereby activation of CHE is sensitive to changes in both the matrix Ca2+ buffering system and the matrix free Ca2+ concentration.

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Dataset Information

MicroRNA-150 modulates intracellular Ca 2+ levels in naive CD8+ T cells by targeting TMEM20.

Publications

MicroRNA-150 modulates intracellular Ca <sup>2+</sup> levels in naïve CD8<sup>+</sup> T cells by targeting TMEM20.

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