Mitochondrial calcium uniporter affects neutrophil bactericidal activity during Staphylococcus aureus infection

2021 ◽  
Author(s):  
Andrew J. Monteith ◽  
Jeanette M. Miller ◽  
William N. Beavers ◽  
K. Nichole Maloney ◽  
Erin L. Seifert ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Bactericidal Activity ◽  
Ion Flux ◽  
Mitochondrial Calcium ◽  
Dependent Manner ◽  
Mitochondrial Calcium Uniporter ◽  
Mitochondrial Homeostasis ◽  
Mitochondrial Superoxide ◽  
Calcium Uniporter ◽  
Mitochondrial Calcium Uptake

Neutrophils simultaneously restrict Staphylococcus aureus dissemination and facilitate bactericidal activity during infection through the formation of neutrophil extracellular traps (NETs). Neutrophils that produce higher levels of mitochondrial superoxide undergo enhanced terminal NET formation (suicidal NETosis) in response to S. aureus ; however, mechanisms regulating mitochondrial homeostasis upstream of neutrophil antibacterial processes are not fully resolved. Here, we demonstrate that mitochondrial calcium uptake 1 (MICU1)-deficient (MICU1 -/- ) neutrophils accumulate higher levels of calcium and iron within the mitochondria in a mitochondrial calcium uniporter (MCU)-dependent manner. Corresponding with increased ion flux through the MCU, mitochondrial superoxide production is elevated, thereby increasing the propensity for MICU1 -/- neutrophils to undergo suicidal NETosis rather than primary degranulation in response to S. aureus . Increased NET formation augments macrophage killing of bacterial pathogens. Similarly, MICU1 -/- neutrophils alone are not more antibacterial towards S. aureus , but rather enhanced suicidal NETosis by MICU1 -/- neutrophils facilitates increased bactericidal activity in the presence of macrophages. Similarly, mice with a deficiency in MICU1 restricted to cells expressing LysM exhibit lower bacterial burdens in the heart with increased survival during systemic S. aureus infection. Coinciding with the decrease in S. aureus burdens, MICU1 -/- neutrophils in the heart produced higher levels of mitochondrial superoxide and undergo enhanced suicidal NETosis. These results demonstrate that ion flux by the MCU affects the antibacterial function of neutrophils during S. aureus infection.

scholarly journals Decision between mitophagy and apoptosis by Parkin via VDAC1 ubiquitination

2020 ◽  
Vol 117 (8) ◽  
pp. 4281-4291 ◽  
Author(s):  
Su Jin Ham ◽  
Daewon Lee ◽  
Heesuk Yoo ◽  
Kyoungho Jun ◽  
Heejin Shin ◽  
...  
Keyword(s):  
Parkinson Disease ◽  
Missense Mutation ◽  
Dopaminergic Neurons ◽  
Calcium Uptake ◽  
Mitochondrial Calcium ◽  
Dependent Manner ◽  
Mitochondrial Calcium Uniporter ◽  
Calcium Uniporter ◽  
Mitochondrial Calcium Uptake ◽  
Transgenic Flies

VDAC1 is a critical substrate of Parkin responsible for the regulation of mitophagy and apoptosis. Here, we demonstrate that VDAC1 can be either mono- or polyubiquitinated by Parkin in a PINK1-dependent manner. VDAC1 deficient with polyubiquitination (VDAC1 Poly-KR) hampers mitophagy, but VDAC1 deficient with monoubiquitination (VDAC1 K274R) promotes apoptosis by augmenting the mitochondrial calcium uptake through the mitochondrial calcium uniporter (MCU) channel. The transgenic flies expressing Drosophila Porin K273R, corresponding to human VDAC1 K274R, show Parkinson disease (PD)-related phenotypes including locomotive dysfunction and degenerated dopaminergic neurons, which are relieved by suppressing MCU and mitochondrial calcium uptake. To further confirm the relevance of our findings in PD, we identify a missense mutation of Parkin discovered in PD patients, T415N, which lacks the ability to induce VDAC1 monoubiquitination but still maintains polyubiquitination. Interestingly, Drosophila Parkin T433N, corresponding to human Parkin T415N, fails to rescue the PD-related phenotypes of Parkin-null flies. Taken together, our results suggest that VDAC1 monoubiquitination plays important roles in the pathologies of PD by controlling apoptosis.

scholarly journals Mitochondrial Calcium Uptake Is Instrumental to Alternative Macrophage Polarization and Phagocytic Activity

2019 ◽  
Vol 20 (19) ◽  
pp. 4966 ◽  
Author(s):  
Tedesco ◽  
Scattolini ◽  
Albiero ◽  
Bortolozzi ◽  
Avogaro ◽  
...  
Keyword(s):  
Phagocytic Activity ◽  
Calcium Uptake ◽  
Macrophage Polarization ◽  
Mitochondrial Calcium ◽  
M2 Macrophage ◽  
M2 Macrophages ◽  
Mitochondrial Calcium Uniporter ◽  
E Coli ◽  
Calcium Uniporter ◽  
Mitochondrial Calcium Uptake

Macrophages are highly plastic and dynamic cells that exert much of their function through phagocytosis. Phagocytosis depends on a coordinated, finely tuned, and compartmentalized regulation of calcium concentrations. We examined the role of mitochondrial calcium uptake and mitochondrial calcium uniporter (MCU) in macrophage polarization and function. In primary cultures of human monocyte-derived macrophages, calcium uptake in mitochondria was instrumental for alternative (M2) macrophage polarization. Mitochondrial calcium uniporter inhibition with KB-R7943 or MCU knockdown, which prevented mitochondrial calcium uptake, reduced M2 polarization, while not affecting classical (M1) polarization. Challenging macrophages with E. coli fragments induced spikes of mitochondrial calcium concentrations, which were prevented by MCU inhibition or silencing. In addition, mitochondria remodelled in M2 macrophages during phagocytosis, especially close to sites of E. coli internalization. Remarkably, inhibition or knockdown of MCU significantly reduced the phagocytic capacity of M2 macrophages. KB-R7943, which also inhibits the membrane sodium/calcium exchanger and Complex I, reduced mitochondria energization and cellular ATP levels, but such effects were not observed with MCU silencing. Therefore, phagocytosis inhibition by MCU knockdown depended on the impaired mitochondrial calcium buffering rather than changes in mitochondrial and cellular energy status. These data uncover a new role for MCU in alternative macrophage polarization and phagocytic activity.

scholarly journals Increased mitochondrial calcium uniporter in adipocytes underlies mitochondrial alterations associated with insulin resistance

2017 ◽  
Vol 313 (6) ◽  
pp. E641-E650 ◽  
Author(s):  
Lauren E. Wright ◽  
Denis Vecellio Reane ◽  
Gabriella Milan ◽  
Anna Terrin ◽  
Giorgia Di Bello ◽  
...  
Keyword(s):  
Adipose Tissue ◽  
Calcium Uptake ◽  
Genetic Manipulation ◽  
Mitochondrial Calcium ◽  
Mitochondrial Calcium Uniporter ◽  
Insulin Resistant ◽  
Calcium Uniporter ◽  
Obesity And Diabetes ◽  
Mitochondrial Calcium Uptake

Intracellular calcium influences an array of pathways and affects cellular processes. With the rapidly progressing research investigating the molecular identity and the physiological roles of the mitochondrial calcium uniporter (MCU) complex, we now have the tools to understand the functions of mitochondrial Ca2+ in the regulation of pathophysiological processes. Herein, we describe the role of key MCU complex components in insulin resistance in mouse and human adipose tissue. Adipose tissue gene expression was analyzed from several models of obese and diabetic rodents and in 72 patients with obesity as well as in vitro insulin-resistant adipocytes. Genetic manipulation of MCU activity in 3T3-L1 adipocytes allowed the investigation of the role of mitochondrial calcium uptake. In insulin-resistant adipocytes, mitochondrial calcium uptake increased and several MCU components were upregulated. Similar results were observed in mouse and human visceral adipose tissue (VAT) during the progression of obesity and diabetes. Intriguingly, subcutaneous adipose tissue (SAT) was spared from overt MCU fluctuations. Furthermore, MCU expression returned to physiological levels in VAT of patients after weight loss by bariatric surgery. Genetic manipulation of mitochondrial calcium uptake in 3T3-L1 adipocytes demonstrated that changes in mitochondrial calcium concentration ([Ca2+]mt) can affect mitochondrial metabolism, including oxidative enzyme activity, mitochondrial respiration, membrane potential, and reactive oxygen species formation. Finally, our data suggest a strong relationship between [Ca2+]mt and the release of IL-6 and TNFα in adipocytes. Altered mitochondrial calcium flux in fat cells may play a role in obesity and diabetes and may be associated with the differential metabolic profiles of VAT and SAT.

scholarly journals Structural insights into the Ca2+-dependent gating of the human mitochondrial calcium uniporter

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Yan Wang ◽  
Yan Han ◽  
Ji She ◽  
Nam X Nguyen ◽  
Vamsi K Mootha ◽  
...  
Keyword(s):  
Mitochondrial Calcium ◽  
Dependent Manner ◽  
Inner Mitochondrial Membrane ◽  
Mitochondrial Calcium Uniporter ◽  
Calcium Uniporter ◽  
Ef Hand ◽  
Conductive Channel ◽  
And Function ◽  
Structural Insights ◽  
Mitochondrial Membrane Protein

Mitochondrial Ca2+ uptake is mediated by an inner mitochondrial membrane protein called the mitochondrial calcium uniporter. In humans, the uniporter functions as a holocomplex consisting of MCU, EMRE, MICU1 and MICU2, among which MCU and EMRE form a subcomplex and function as the conductive channel while MICU1 and MICU2 are EF-hand proteins that regulate the channel activity in a Ca2+-dependent manner. Here, we present the EM structures of the human mitochondrial calcium uniporter holocomplex (uniplex) in the presence and absence of Ca2+, revealing distinct Ca2+ dependent assembly of the uniplex. Our structural observations suggest that Ca2+ changes the dimerization interaction between MICU1 and MICU2, which in turn determines how the MICU1-MICU2 subcomplex interacts with the MCU-EMRE channel and, consequently, changes the distribution of the uniplex assemblies between the blocked and unblocked states.

scholarly journals Structural insights into the Ca2+-dependent gating of the human mitochondrial calcium uniporter

2020 ◽  
Author(s):  
Yan Wang ◽  
Yan Han ◽  
Ji She ◽  
Nam X. Nguyen ◽  
Vamsi K. Mootha ◽  
...  
Keyword(s):  
Electrostatic Interactions ◽  
Mitochondrial Calcium ◽  
Dependent Manner ◽  
Inner Mitochondrial Membrane ◽  
Mitochondrial Calcium Uniporter ◽  
Channel Pore ◽  
Atp Production ◽  
Calcium Uniporter ◽  
Ef Hand ◽  
And Function

AbstractMitochondrial Ca2+ uptake plays an important role in cellular physiology such as modulating ATP production, regulating cytoplasmic Ca2+ dynamics, and triggering cell death, and is mediated by the mitochondrial calcium uniporter, a highly selective calcium channel localized to the inner mitochondrial membrane. In humans, the uniporter functions as a holocomplex consisting of MCU, EMRE, MICU1 and MICU2, among which MCU and EMRE form a subcomplex and function as the conductive channel while MICU1 and MICU2 are EF-hand proteins that regulate the channel activity in a Ca2+ dependent manner. Here we present the EM structures of the human mitochondrial calcium uniporter holocomplex (uniplex) in the presence and absence of Ca2+, revealing distinct Ca2+ dependent assembly of the uniplex. In the presence of Ca2+, MICU1 and MICU2 form a heterotetramer of MICU1-(MICU2)2-MICU1 and bridge the dimeric form of the MCU-EMRE subcomplex through electrostatic interactions between MICU1 and EMRE, leaving the MCU channel pore unblocked. In the absence of Ca2+, multiple uniplex assemblies are observed but is predominantly occupied by the MICU1 subunit from a MICU1-MICU2 heterodimer blocking the MCU channel pore. Our structural observations suggest that Ca2+ changes the dimerization interaction between MICU1 and MICU2, which in turn determines how the MICU1-MICU2 subcomplex interacts with the MCU-EMRE channel and, consequently, changes the distribution of the uniplex assemblies between the blocked and unblocked states.

288-LB: Effects of the Hepatic Mitochondrial Calcium Uniporter on Hepatic Gluconeogenesis and Mitochondrial Metabolism in Awake Mice

Diabetes ◽  
2019 ◽  
Vol 68 (Supplement 1) ◽  
pp. 288-LB
Author(s):  
JI EUN LEE ◽  
LEIGH GOEDEKE ◽  
YE ZHANG ◽  
RACHEL J. PERRY ◽  
RUSSELL GOODMAN ◽  
...  
Keyword(s):  
Mitochondrial Metabolism ◽  
Mitochondrial Calcium ◽  
Hepatic Gluconeogenesis ◽  
Mitochondrial Calcium Uniporter ◽  
Calcium Uniporter
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