The Mitochondrial Calcium Uniporter Controls Skeletal Muscle Trophism In Vivo

Mitochondria are believed to play an important role in shaping the intracellular Ca2+ transients during skeletal muscle contraction. There is discussion about whether mitochondrial matrix Ca2+ dynamics always mirror the cytoplasmic changes and whether this happens in vivo in whole organisms. In this study, we characterized cytosolic and mitochondrial Ca2+ signals during spontaneous skeletal muscle contractions in zebrafish embryos expressing bioluminescent GFP-aequorin (GA, cytoplasm) and mitoGFP-aequorin (mitoGA, trapped in the mitochondrial matrix). The Ca2+ transients measured with GA and mitoGA reflected contractions of the trunk observed by transmitted light. The mitochondrial uncoupler FCCP and the inhibitor of the mitochondrial calcium uniporter (MCU), DS16570511, abolished mitochondrial Ca2+ transients whereas they increased the frequency of cytosolic Ca2+ transients and muscle contractions, confirming the subcellular localization of mitoGA. Mitochondrial Ca2+ dynamics were also determined with mitoGA and were found to follow closely cytoplasmic changes, with a slower decay. Cytoplasmic Ca2+ kinetics and propagation along the trunk and tail were characterized with GA and with the genetically encoded fluorescent Ca2+ indicator, Twitch-4. Although fluorescence provided a better spatio-temporal resolution, GA was able to resolve the same kinetic parameters while allowing continuous measurements for hours.

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A novel protoapigenone analog RY10-4 induces apoptosis of breast cancer cells by regulating mitochondrial Ca2+ influx through the mitochondrial calcium uniporter

10.21203/rs.3.rs-17058/v1 ◽

2020 ◽

Author(s):

Pingping Xue ◽

Qian Chen ◽

Xiuhua Ren ◽

Yimin Yang ◽

Xiaofan Yang ◽

...

Keyword(s):

Breast Cancer ◽

Cancer Cells ◽

Breast Cancer Cells ◽

Flavonoid Compound ◽

Mitochondrial Calcium ◽

Mitochondrial Apoptosis ◽

Apoptosis Pathway ◽

Mitochondrial Calcium Uniporter ◽

Calcium Uniporter

Abstract Background Protoapigenone, as a flavonoid compound with a specific nonaromatic B-ring, exhibits extraordinary antitumor activities against a broad spectrum of human cancer cells. Here we developed a novel protoapigenone analog RY10-4, which induces the apoptosis of various tumor cells, especially for breast cancer cells, but the underlying mechanism involved in the apoptotic process remains unclear. Methods MTT assay, colony-formation assay and flow cytometry were applied to evaluate the proliferation and apoptosis of breast cancer cells. Cytoplasmic calcium ([Ca2+]c) and mitochondrial calcium ([Ca2+]m) of the breast cancer cells were measured by the Fluo-2 and Rhod-2 probes, respectively. The mitochondrial reactive oxygen species (mtROS), membrane potential (ΔΨm) and permeability transition pore (mPTP) were analyzed by MitoSOX, JC-1 probes and Calcein/AM, respectively. Furthermore, Western bolt assay was adopted for the exploration of the mitochondrial apoptosis pathway. Besides, the xenograft assay was performed to investigate the role of RY10-4 in breast cancer cells in vivo. Results Obviously, RY10-4 could effectively suppress the proliferation and induce the apoptosis of breast cancer cells. Furthermore, the [Ca2+]c and [Ca2+]m of MDA-MB-231 cells were up-regulated after the treatment of RY10-4, resulting in the mtROS accumulation, ΔΨm depolarization and mPTP opening. And finally, the mitochondrial apoptosis was activated by the release of cytochrome C. Interestingly, the inhibition of mitochondrial calcium uniporter (MCU) with Ru360 attenuated the overload of [Ca2+]m and blocked the apoptosis of MDA-MB-231 cells induced by RY10-4, which was also consistent with the in vivo results. Conclusions From the results we concluded that RY10-4 could induce apoptosis of breast cancer cells by elevating [Ca2+]m through MCU. Our work contributed previously unknown insights into the mechanisms involving in the clinical efficacy of RY10-4 on breast cancer cells, which also advanced calcium homeostasis as a potential target for chemotherapeutic drugs.

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The mitochondrial calcium uniporter is crucial for the generation of fast cortical network rhythms

Journal of Cerebral Blood Flow & Metabolism ◽

10.1177/0271678x19887777 ◽

2019 ◽

Vol 40 (11) ◽

pp. 2225-2239 ◽

Cited By ~ 3

Author(s):

Carlos Bas-Orth ◽

Justus Schneider ◽

Andrea Lewen ◽

Jamie McQueen ◽

Kerstin Hasenpusch-Theil ◽

...

Keyword(s):

Energy Homeostasis ◽

Pyramidal Cells ◽

Gamma Oscillations ◽

Spike Timing ◽

Mitochondrial Calcium ◽

Attention And Memory ◽

Mitochondrial Calcium Uniporter ◽

Sharp Waves ◽

Calcium Uniporter

The role of the mitochondrial calcium uniporter (MCU) gene ( Mcu) in cellular energy homeostasis and generation of electrical brain rhythms is widely unknown. We investigated this issue in mice and rats using Mcu-knockout and -knockdown strategies in vivo and in situ and determined the effects of these genetic manipulations on hippocampal gamma oscillations (30–70 Hz) and sharp wave-ripples. These physiological network states require precise neurotransmission between pyramidal cells and inhibitory interneurons, support spike-timing and synaptic plasticity and are associated with perception, attention and memory. Absence of the MCU resulted in (i) gamma oscillations with decreased power (by >40%) and lower synchrony, including less precise neural action potential generation (‘spiking'), (ii) sharp waves with decreased incidence (by about 22%) and decreased fast ripple frequency (by about 3%) and (iii) lack of activity-dependent pyruvate dehydrogenase dephosphorylation. However, compensatory adaptation in gene expression related to mitochondrial function and glucose metabolism was not detected. These data suggest that the neuronal MCU is crucial for the generation of network rhythms, most likely by influences on oxidative phosphorylation and perhaps by controlling cytoplasmic Ca2+ homeostasis. This work contributes to an increased understanding of mitochondrial Ca2+ uptake in cortical information processing underlying cognition and behaviour.

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Abstract 14553: Mitochondrial Calcium Uptake via Mitochondrial Calcium Uniporter Suppress Ventricular Arrhythmia in the Ischemic Heart Failure Mice

Circulation ◽

10.1161/circ.142.suppl_3.14553 ◽

2020 ◽

Vol 142 (Suppl_3) ◽

Author(s):

Hikaru Hagiwara ◽

Masaya Watanabe ◽

Yoichiro Fujioka, ◽

Taro Koya ◽

Motoki Nakao ◽

...

Keyword(s):

Heart Failure ◽

Left Ventricular ◽

Epifluorescence Microscopy ◽

Mitochondrial Calcium ◽

Coronary Artery Ligation ◽

Sham Operation ◽

Artery Ligation ◽

Mitochondrial Calcium Uniporter ◽

Calcium Uniporter

Background: Delayed after depolarization by calcium (Ca 2+ ) leak from sarcoplasmic reticulum (SR) via Ryanodine receptor is one of the causes of ventricular arrhythmias (VAs) in heart failure (HF). Ca 2+ uptake into mitochondria via mitochondrial calcium uniporter (MCU) is participated in Ca 2+ handling, but the relationship between VAs in HF and Ca 2+ uptake into mitochondria is unclear. Purpose: We sought to investigate whether increased Ca 2+ uptake into mitochondria via MCU reduces diastolic Ca 2+ leak and suppresses VAs in ischemic HF mice. Methods: Ten-week-old male C57BL/6J mice were divided into 2 groups; sham operation mice (Sham) or HF mice (HF) in which myocardial infarction was induced by left coronary artery ligation. After 4-6 weeks, cardiomyocyte or mitochondria were isolated respectively from the myocardium of Sham and the non-infarct myocardium of HF. Ca 2+ waves (CaWs) were measured on an epifluorescence microscopy. Calcium transients and calcium sparks were measured on a confocal microscope in linescan mode. Mitochondrial Ca 2+ uptake were measured by estimating the extra-mitochondrial Ca 2+ reduction with Fluo-5N on a spectrofluoro-photometer. VAs was induced in the Langendorff perfused hearts. Left ventricular (LV) pressure was measured using a microtip transducer catheter . Results: HF mice showed left ventricular dysfunction and increased heart and lung weights compared to Sham. Kaempferol, a MCU activator, increased mitochondrial Ca 2+ uptake in the isolated mitochondria both in Sham and HF. CaWs and Ca spark frequency in the presence of isoproterenol was attenuated by 10 μM Kaempferol. Kaempferol did not show significant changes in Ca 2+ transient amplitude, however increased the time to 50% decay significantly. The incidence of induced VAs was suppressed by Kaempferol. In vivo measurements, intravenous administration of Kaempferol (5mg/kg) did not show significant changes in hemodynamic parameters in HF mice. Conclusions: Ca 2+ uptake into mitochondria via MCU suppresses VAs in HF. Despite the adverse influence of the traditional antiarrhythmic drugs for HF condition, a novel strategy that promotes Ca 2+ uptake into mitochondria might be a potential therapeutic approach for VA treatment in HF patients.

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Abstract 513: Emre Regulates the Mitochondrial Calcium Uniporter in vivo

Circulation Research ◽

10.1161/res.127.suppl_1.513 ◽

2020 ◽

Vol 127 (Suppl_1) ◽

Author(s):

Julia C Liu ◽

Nicole Syder ◽

Nima Ghorashi ◽

Thomas B Willingham ◽

Randi J Parks ◽

...

Keyword(s):

Ischemia Reperfusion Injury ◽

Transmembrane Protein ◽

Ischemia Reperfusion ◽

Strenuous Exercise ◽

Mitochondrial Calcium ◽

Mitochondrial Calcium Uniporter ◽

Isolated Mitochondria ◽

Mendelian Genetics ◽

Calcium Uniporter

Mitochondrial uptake of Ca 2+ plays critical roles in cardiac energy production as well as cell death. The mitochondrial calcium uniporter in mice and humans is a multi-protein complex that includes the channel-forming protein MCU and several other subunit proteins, including EMRE. EMRE is a single transmembrane protein that is conserved among metazoan species and is known to be essential for mitochondrial Ca 2+ uptake in cell culture. To investigate EMRE’s role in organismal physiology, we generated a mouse model of global germline EMRE deletion. We show that EMRE is indeed required for mitochondrial calcium uniporter function in isolated mitochondria from multiple tissues. Although the birth rate of Emre -/- mice is lower than expected by Mendelian genetics (~5-10% instead of ~25%), the mice that are born are viable and appear healthy. Oxygen consumption in isolated mitochondria and cells is not significantly affected by loss of EMRE, and similarly the mice do not exhibit overt metabolic impairment, even under strenuous exercise. No significant differences between Emre -/- and wild-type ( WT ) cardiac function at baseline and after isoproterenol stimulation are evident by echocardiography. Moreover, Emre -/ - hearts are not protected from ischemia/reperfusion injury in a Langendorff perfusion model (mean infarct area 61% in Emre -/- hearts; 57% in WT ). Collectively, these data and their similarities to results found via germline Mcu deletion demonstrate that EMRE is indeed essential for mitochondrial Ca 2+ uptake in vivo. Furthermore, we find evidence that EMRE protein expression is elevated in some mouse muscular dystrophy models, suggesting that modulation of EMRE levels may play a role in regulating uniporter activity in conditions of stress or disease. We therefore further explore whether and how EMRE expression changes with isoproterenol-induced cardiac hypertrophy in mice and in samples from human patients with heart failure. Understanding of how uniporter components such as EMRE can regulate MCU in a diseased state can inform better therapeutic strategies aimed at restoring mitochondrial metabolic homeostasis.

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Exploring the In Vivo Role of the Mitochondrial Calcium Uniporter in Brown Fat Bioenergetics

Cell Reports ◽

10.1016/j.celrep.2019.04.013 ◽

2019 ◽

Vol 27 (5) ◽

pp. 1364-1375.e5 ◽

Cited By ~ 6

Author(s):

Daniel Flicker ◽

Yasemin Sancak ◽

Eran Mick ◽

Olga Goldberger ◽

Vamsi K. Mootha

Keyword(s):

Brown Fat ◽

Mitochondrial Calcium ◽

Mitochondrial Calcium Uniporter ◽

Calcium Uniporter

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The mitochondrial calcium uniporter underlies metabolic fuel preference in skeletal muscle

JCI Insight ◽

10.1172/jci.insight.121689 ◽

2018 ◽

Vol 3 (22) ◽

Cited By ~ 21

Author(s):

Jennifer Q. Kwong ◽

Jiuzhou Huo ◽

Michael J. Bround ◽

Justin G. Boyer ◽

Jennifer A. Schwanekamp ◽

...

Keyword(s):

Skeletal Muscle ◽

Mitochondrial Calcium ◽

Mitochondrial Calcium Uniporter ◽

Metabolic Fuel ◽

Calcium Uniporter ◽

Fuel Preference

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An essential role for cardiolipin in the stability and function of the mitochondrial calcium uniporter

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.2000640117 ◽

2020 ◽

Vol 117 (28) ◽

pp. 16383-16390 ◽

Cited By ~ 9

Author(s):

Sagnika Ghosh ◽

Writoban Basu Ball ◽

Travis R. Madaris ◽

Subramanya Srikantan ◽

Muniswamy Madesh ◽

...

Keyword(s):

Calcium Transport ◽

Cardiac Tissue ◽

Barth Syndrome ◽

Mitochondrial Calcium ◽

Mitochondrial Calcium Uniporter ◽

Cellular Models ◽

Calcium Uniporter ◽

Protein Components ◽

And Function

Calcium uptake by the mitochondrial calcium uniporter coordinates cytosolic signaling events with mitochondrial bioenergetics. During the past decade all protein components of the mitochondrial calcium uniporter have been identified, including MCU, the pore-forming subunit. However, the specific lipid requirements, if any, for the function and formation of this channel complex are currently not known. Here we utilize yeast, which lacks the mitochondrial calcium uniporter, as a model system to address this problem. We use heterologous expression to functionally reconstitute human uniporter machinery both in wild-type yeast as well as in mutants defective in the biosynthesis of phosphatidylethanolamine, phosphatidylcholine, or cardiolipin (CL). We uncover a specific requirement of CL for in vivo reconstituted MCU stability and activity. The CL requirement of MCU is evolutionarily conserved with loss of CL triggering rapid turnover of MCU homologs and impaired calcium transport. Furthermore, we observe reduced abundance and activity of endogenous MCU in mammalian cellular models of Barth syndrome, which is characterized by a partial loss of CL. MCU abundance is also decreased in the cardiac tissue of Barth syndrome patients. Our work raises the hypothesis that impaired mitochondrial calcium transport contributes to the pathogenesis of Barth syndrome, and more generally, showcases the utility of yeast phospholipid mutants in dissecting the phospholipid requirements of ion channel complexes.

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Physical exercise in aging human skeletal muscle increases mitochondrial calcium uniporter expression levels and affects mitochondria dynamics

Physiological Reports ◽

10.14814/phy2.13005 ◽

2016 ◽

Vol 4 (24) ◽

pp. e13005 ◽

Cited By ~ 32

Author(s):

Sandra Zampieri ◽

Cristina Mammucari ◽

Vanina Romanello ◽

Laura Barberi ◽

Laura Pietrangelo ◽

...

Keyword(s):

Skeletal Muscle ◽

Physical Exercise ◽

Human Skeletal Muscle ◽

Mitochondrial Calcium ◽

Mitochondrial Calcium Uniporter ◽

Expression Levels ◽

Calcium Uniporter ◽

Mitochondria Dynamics

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Pharmacological modulation of mitochondrial calcium uniporter controls lung inflammation in cystic fibrosis

Science Advances ◽

10.1126/sciadv.aax9093 ◽

2020 ◽

Vol 6 (19) ◽

pp. eaax9093 ◽

Cited By ~ 6

Author(s):

Alessandro Rimessi ◽

Chiara Pozzato ◽

Lorenzo Carparelli ◽

Alice Rossi ◽

Serena Ranucci ◽

...

Keyword(s):

Cystic Fibrosis ◽

Endoplasmic Reticulum ◽

Tyrosine Phosphatase ◽

Mitochondrial Calcium ◽

Inflammasome Activation ◽

Interacting Protein ◽

Mitochondrial Calcium Uniporter ◽

Calcium Uniporter

Mitochondria physically associate with the endoplasmic reticulum to coordinate interorganelle calcium transfer and regulate fundamental cellular processes, including inflammation. Deregulated endoplasmic reticulum–mitochondria cross-talk can occur in cystic fibrosis, contributing to hyperinflammation and disease progression. We demonstrate that Pseudomonas aeruginosa infection increases endoplasmic reticulum–mitochondria associations in cystic fibrosis bronchial cells by stabilizing VAPB-PTPIP51 (vesicle-associated membrane protein–associated protein B–protein tyrosine phosphatase interacting protein 51) tethers, affecting autophagy. Impaired autophagy induced mitochondrial unfolding protein response and NLRP3 inflammasome activation, contributing to hyperinflammation. The mechanism by which VAPB-PTPIP51 tethers regulate autophagy in cystic fibrosis involves calcium transfer via mitochondrial calcium uniporter. Mitochondrial calcium uniporter inhibition rectified autophagy and alleviated the inflammatory response in vitro and in vivo, resulting in a valid therapeutic strategy for cystic fibrosis pulmonary disease.

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