Targeting Cpt1a-Bcl-2 interaction modulates apoptosis resistance and fibrotic remodeling

AbstractThe mitochondrial calcium uniporter (MCU) regulates metabolic reprogramming in lung macrophages and the progression of pulmonary fibrosis. Fibrosis progression is associated with apoptosis resistance in lung macrophages; however, the mechanism(s) by which apoptosis resistance occurs is poorly understood. Here, we found a marked increase in mitochondrial B-cell lymphoma-2 (Bcl-2) in lung macrophages from subjects with idiopathic pulmonary fibrosis (IPF). Similar findings were seen in bleomycin-injured wild-type (WT) mice, whereas Bcl-2 was markedly decreased in mice expressing a dominant-negative mitochondrial calcium uniporter (DN-MCU). Carnitine palmitoyltransferase 1a (Cpt1a), the rate-limiting enzyme for fatty acid β-oxidation, directly interacted with Bcl-2 by binding to its BH3 domain, which anchored Bcl-2 in the mitochondria to attenuate apoptosis. This interaction was dependent on Cpt1a activity. Lung macrophages from IPF subjects had a direct correlation between CPT1A and Bcl-2, whereas the absence of binding induced apoptosis. The deletion of Bcl-2 in macrophages protected mice from developing pulmonary fibrosis. Moreover, mice had resolution when Bcl-2 was deleted or was inhibited with ABT-199 after fibrosis was established. These observations implicate an interplay between macrophage fatty acid β-oxidation, apoptosis resistance, and dysregulated fibrotic remodeling.

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Mitochondrial calcium uniporter regulates PGC-1α expression to mediate metabolic reprogramming in pulmonary fibrosis

Redox Biology ◽

10.1016/j.redox.2019.101307 ◽

2019 ◽

Vol 26 ◽

pp. 101307 ◽

Cited By ~ 7

Author(s):

Linlin Gu ◽

Jennifer L. Larson Casey ◽

Shaida A. Andrabi ◽

Jun Hee Lee ◽

Selene Meza-Perez ◽

...

Keyword(s):

Pulmonary Fibrosis ◽

Metabolic Reprogramming ◽

Mitochondrial Calcium ◽

Mitochondrial Calcium Uniporter ◽

Calcium Uniporter

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Different Roles of Mitochondrial Calcium Uniporter Complex Subunits in Growth and Infectivity of Trypanosoma cruzi

mBio ◽

10.1128/mbio.00574-17 ◽

2017 ◽

Vol 8 (3) ◽

Cited By ~ 37

Author(s):

Miguel A. Chiurillo ◽

Noelia Lander ◽

Mayara S. Bertolini ◽

Melissa Storey ◽

Anibal E. Vercesi ◽

...

Keyword(s):

Trypanosoma Cruzi ◽

Human Cells ◽

Dominant Negative ◽

Negative Regulator ◽

Host Cells ◽

Dominant Negative Effect ◽

Mitochondrial Calcium ◽

Mitochondrial Calcium Uniporter ◽

Calcium Uniporter ◽

Molecular Nature

ABSTRACT Trypanosoma cruzi is the agent of Chagas disease, and the finding that this parasite possesses a mitochondrial calcium uniporter (TcMCU) with characteristics similar to that of mammalian mitochondria was fundamental for the discovery of the molecular nature of MCU in eukaryotes. We report here that ablation of TcMCU , or its paralog TcMCUb , by clustered regularly interspaced short palindromic repeat (CRISPR)/Cas9 led to a marked decrease in mitochondrial Ca 2+ uptake without affecting the membrane potential of these cells, whereas overexpression of each gene caused a significant increase in the ability of mitochondria to accumulate Ca 2+ . While TcMCU- knockout (KO) epimastigotes were viable and able to differentiate into trypomastigotes, infect host cells, and replicate normally, ablation of TcMCUb resulted in epimastigotes having an important growth defect, lower rates of respiration and metacyclogenesis, more pronounced autophagy changes under starvation, and significantly reduced infectivity. Overexpression of TcMCUb , in contrast to what was proposed for its mammalian ortholog, did not result in a dominant negative effect on TcMCU. IMPORTANCE The finding of a mitochondrial calcium uniporter (MCU) in Trypanosoma cruzi was essential for the discovery of the molecular nature of this transporter in mammals. In this work, we used the CRISPR/Cas9 technique that we recently developed for T. cruzi to knock out two components of the uniporter: MCU, the pore subunit, and MCUb, which was proposed as a negative regulator of MCU in human cells. In contrast to what occurs in human cells, MCU is not essential, while MCUb is essential for growth, differentiation, and infectivity; has a bioenergetic role; and does not act as a dominant negative subunit of MCU.

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Bcl-2 Regulation by the Mitochondrial Calcium Uniporter Modulates Pulmonary Fibrosis

10.1164/ajrccm-conference.2020.201.1_meetingabstracts.a7875 ◽

2020 ◽

Author(s):

L. Gu ◽

J.L. Casey ◽

D. Davis ◽

J. Kang ◽

A.B.B. Carter

Keyword(s):

Pulmonary Fibrosis ◽

Mitochondrial Calcium ◽

Mitochondrial Calcium Uniporter ◽

Calcium Uniporter

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Cardiac-specific deficiency of the mitochondrial calcium uniporter augments fatty acid oxidation and functional reserve

Journal of Molecular and Cellular Cardiology ◽

10.1016/j.yjmcc.2018.12.019 ◽

2019 ◽

Vol 127 ◽

pp. 223-231 ◽

Cited By ~ 11

Author(s):

Tariq R. Altamimi ◽

Qutuba G. Karwi ◽

Golam Mezbah Uddin ◽

Arata Fukushima ◽

Jennifer Q. Kwong ◽

...

Keyword(s):

Fatty Acid ◽

Fatty Acid Oxidation ◽

Acid Oxidation ◽

Mitochondrial Calcium ◽

Functional Reserve ◽

Mitochondrial Calcium Uniporter ◽

Calcium Uniporter

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Restoring mitochondrial calcium uniporter expression in diabetic mouse heart improves mitochondrial calcium handling and cardiac function

Journal of Biological Chemistry ◽

10.1074/jbc.ra118.002066 ◽

2018 ◽

Vol 293 (21) ◽

pp. 8182-8195 ◽

Cited By ~ 24

Author(s):

Jorge Suarez ◽

Federico Cividini ◽

Brian T. Scott ◽

Kim Lehmann ◽

Julieta Diaz-Juarez ◽

...

Keyword(s):

Cardiac Function ◽

Glucose Oxidation ◽

Cardiac Myocyte ◽

Diabetic Mouse ◽

Metabolic Reprogramming ◽

Mitochondrial Calcium ◽

Adeno Associated Virus ◽

Mitochondrial Calcium Uniporter ◽

Calcium Uniporter ◽

And Function

Diabetes mellitus is a growing health care problem, resulting in significant cardiovascular morbidity and mortality. Diabetes also increases the risk for heart failure (HF) and decreased cardiac myocyte function, which are linked to changes in cardiac mitochondrial energy metabolism. The free mitochondrial calcium level ([Ca2+]m) is fundamental in activating the mitochondrial respiratory chain complexes and ATP production and is also known to regulate pyruvate dehydrogenase complex (PDC) activity. The mitochondrial calcium uniporter (MCU) complex (MCUC) plays a major role in mediating mitochondrial Ca2+ import, and its expression and function therefore have a marked impact on cardiac myocyte metabolism and function. Here, we investigated MCU's role in mitochondrial Ca2+ handling, mitochondrial function, glucose oxidation, and cardiac function in the heart of diabetic mice. We found that diabetic mouse hearts exhibit altered expression of MCU and MCUC members and a resulting decrease in [Ca2+]m, mitochondrial Ca2+ uptake, mitochondrial energetic function, and cardiac function. Adeno-associated virus-based normalization of MCU levels in these hearts restored mitochondrial Ca2+ handling, reduced PDC phosphorylation levels, and increased PDC activity. These changes were associated with cardiac metabolic reprogramming toward normal physiological glucose oxidation. This reprogramming likely contributed to the restoration of both cardiac myocyte and heart function to nondiabetic levels without any observed detrimental effects. These findings support the hypothesis that abnormal mitochondrial Ca2+ handling and its negative consequences can be ameliorated in diabetes by restoring MCU levels via adeno-associated virus–based MCU transgene expression.

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