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Ca2+ flux into mitochondria is an important regulator of cytoplasmic Ca2+ signals, energy production and cell death pathways. Ca2+ uptake can occur through the recently discovered mitochondrial uniporter channel (MCU) but whether the MCU is involved in shaping Ca2+ signals and downstream responses to physiological levels of receptor stimulation is unknown. Here, we show that modest stimulation of leukotriene receptors with the pro-inflammatory signal LTC4 evokes a series of cytoplasmic Ca2+ oscillations that are rapidly and faithfully propagated into mitochondrial matrix. Knockdown of MCU or mitochondrial depolarisation, to reduce the driving force for Ca2+ entry into the matrix, prevents the mitochondrial Ca2+ rise and accelerates run down of the oscillations. The loss of cytoplasmic Ca2+ oscillations appeared to be a consequence of enhanced Ca2+-dependent inactivation of InsP3 receptors, which arose from the loss of mitochondrial Ca2+ buffering. Ca2+ dependent gene expression in response to leukotriene receptor activation was suppressed following knockdown of the MCU. In addition to buffering Ca2+ release, mitochondria also sequestrated Ca2+ entry through store-operated Ca2+ channels and this too was prevented following loss of MCU. MCU is therefore an important regulator of physiological pulses of cytoplasmic Ca2+.

Original publication

DOI

10.1371/journal.pone.0101188

Type

Journal article

Journal

PLoS One

Publication Date

2014

Volume

9

Keywords

Animals, Calcium, Calcium Channels, Calcium Signaling, Cytoplasm, Gene Expression Regulation, Inositol 1,4,5-Trisphosphate Receptors, Ion Transport, Leukemia, Basophilic, Acute, Membrane Potential, Mitochondrial, Mitochondria, RNA, Messenger, Rats, Real-Time Polymerase Chain Reaction, Reverse Transcriptase Polymerase Chain Reaction, Signal Transduction, Tumor Cells, Cultured