DFF40 translocates to the mitochondria during apoptosis and regulates mitochondrial integrity and function

2021 ◽  
Author(s):  
Merve Kulbay ◽  
Bruno Johnson ◽  
Guillaume Ricaud ◽  
Marie-Noelle Séguin-Grignon ◽  
Valérie Malboeuf ◽  
...  
Keyword(s):  
Mitochondrial Membrane ◽  
Cell Metabolism ◽  
Membrane Integrity ◽  
Basal Respiration ◽  
Mtdna Copy Number ◽  
Apoptosis Resistance ◽  
Atp Production ◽  
Mitochondrial Integrity ◽  
Resistance Pathway ◽  
And Function

Abstract DNA fragmentation factor 40 (DFF40), or the caspase-activated DNase (CAD), is an endonuclease specific for double-stranded DNA. Alterations in its function and expression have been linked to apoptosis resistance, a mechanism likely used by cancer cells. Although, how the DFF40-related apoptosis resistance pathway occurs remains unclear. Here we sought to determine if DFF40 could localize to the mitochondrion, a localization not reported in the literature until now, and further regulate cell metabolism when apoptosis is activated. We demonstrated that DFF40 localizes in mitochondria through its N-terminal domain, and its agglomeration is accentuated in apoptosis-activated cells. We also found that a loss of DFF40 expression induces a higher mitochondrial mass, mtDNA copy number, mitochondrial membrane potential, and glycolysis rates in resting T cells. The induction of apoptosis in DFF40 deficient cells doesn’t alter ATP production levels, basal respiration, and mitochondrial membrane integrity. Our study reveals that DFF40 may act as a regulator of mitochondria, and its loss could compromise mitochondrial integrity in pathologies such as cancer.

scholarly journals CBMT-17. DEFECTIVE QKI-DEPENDENT LIPID METABOLISM INDUCES GENOMIC INSTABILITY AND SENSITIZES GLIOBLASTOMA TO IMMUNOTHERAPY

2019 ◽  
Vol 21 (Supplement_6) ◽  
pp. vi36-vi36
Author(s):  
Takashi Shingu ◽  
Jian Hu
Keyword(s):  
Genomic Instability ◽  
Mitochondrial Membrane ◽  
Rna Binding ◽  
Cytoplasmic Membrane ◽  
Unsaturated Fatty Acids ◽  
Rna Stability ◽  
Membrane Integrity ◽  
Immune Checkpoints ◽  
Mitochondrial Defects ◽  
And Function

Abstract Despite transformative effects on the therapy of cancers such as melanoma and lung adenocarcinoma, blockade of the T cell immune checkpoints has generated limited impact on glioblastoma. Identifying genetic/genomic alterations that could potentially sensitize the patients to immunotherapy will significantly improve the efficacy of immunotherapy on glioblastoma patients. As part of our effort to identify novel glioma suppressors that affect the interaction of GSCs with their microenvironment, we discovered that the RNA-binding protein Quaking (QKI) is a key regulator of cellular endocytosis. QKI is mutated or deleted in ~34% of human glioblastomas. Supporting QKI’s tumor suppresser function, 92% of the Nestin-CreERT2;QkiL/L;PtenL/L;p53L/L mice developed glioblastoma with a median survival of 105 days, however, the Nestin-CreERT2;PtenL/L;p53L/L mice did not develop any glioma up to a year. Mechanistically, QKI regulates the RNA stability and alternative splicing of numerous protein and lipid components of endolysosomes, particularly the unsaturated fatty acids (UFAs). Functionally, deletion of Qki and inhibition of UFA biosynthesis both decrease endolysosome-mediated receptor degradation, thereby enriching receptors on the cytoplasmic membrane (e.g., Frizzled and Notch1) that are essential for maintaining stemness. This enrichment of receptor signaling enables GSCs to cope with the low ligand levels during their invasion. On the other hand, lower lysosomal activity induced by Qki deletion and UFA loss led to defective mitophagy. We also found that insufficient UFAs in mitochondrial membrane significantly compromised mitochondrial membrane integrity and function. These two mechanisms concomitantly led to accumulation of damaged mitochondria and higher levels of reactive oxygen species (ROS), and consequently genomic instability. Lastly, we found that the higher level of genomic instability induced by Qki loss rendered cells more sensitive to anti-CTLA4 and anti-PD1 antibodies. Taken together, our data suggest that Qki/UFA loss-induced endolysosomal and mitochondrial defects promote gliomagenesis yet render cells vulnerabilities that could be harnessed for therapeutic purposes.

scholarly journals Metformin Preserves Mitochondrial Integrity at Old Age in Male Rats

2021 ◽  
Vol 5 (Supplement_1) ◽  
pp. 690-690
Author(s):  
Jonathan Wanagat ◽  
Allen Herbst ◽  
Austin Hoang ◽  
Chiye Kim ◽  
Judd Aiken ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Copy Number ◽  
Male Rats ◽  
Metformin Treatment ◽  
Mtdna Copy Number ◽  
C Elegans ◽  
Mitochondrial Integrity ◽  
Mitochondrial Dna Copy Number ◽  
And Function ◽  
Deletion Frequency

Abstract Metformin is being deployed in clinical trials to ameliorate aging in older humans who do not have diabetes. In C. elegans, metformin treatment at old ages exacerbated mitochondrial dysfunction, led to respiratory failure, and shortened lifespan. Metformin is a commonly used, well-tolerated treatment for diabetes in older adults. Mitochondrial effects of metformin treatment in aged mammals has not been sufficiently investigated. We hypothesized that metformin treatment would not be toxic to older mammals. To define a therapeutic dose in aged hybrid rats, we evaluated two doses of metformin (0.1%, 0.75% of the diet) at 30-months of age. Body mass decreased at the 0.75% dose. Neither dose affected mortality between 30- and 34-months of age. We assessed mitochondrial quality, quantity, and function in aged rats treated with metformin at the 0.75% dose by measuring mitochondrial DNA copy number, deletion mutation frequency, and respirometry in skeletal muscle and heart. In skeletal muscle, we observed no effect of metformin on quadriceps mass, mtDNA copy number or deletion frequency. In the heart, metformin treated rats had higher mtDNA copy number, lower cardiac mass and no effect on deletion frequency. Metformin treatment resulted in lower mitochondrial complex I activity in both heart and quadriceps. Metformin did not compromise mitochondrial integrity, was well tolerated, and may have cardiac benefits to rats at old ages.

Effects of hypoxia, anoxia, and metabolic inhibitors on KATP channels in rat femoral artery myocytes

2006 ◽  
Vol 291 (1) ◽  
pp. H71-H80 ◽  
Author(s):  
J. M. Quayle ◽  
M. R. Turner ◽  
H. E. Burrell ◽  
T. Kamishima
Keyword(s):  
Membrane Potential ◽  
Mitochondrial Membrane Potential ◽  
Atp Synthase ◽  
Femoral Artery ◽  
Mitochondrial Membrane ◽  
Cell Metabolism ◽  
Metabolic Inhibitors ◽  
Channel Activity ◽  
Patch Clamp Technique ◽  
Atp Production

Vascular ATP-sensitive potassium (KATP) channels have an important role in hypoxic vasodilation. Because KATP channel activity depends on intracellular nucleotide concentration, one hypothesis is that hypoxia activates channels by reducing cellular ATP production. However, this has not been rigorously tested. In this study we measured KATP current in response to hypoxia and modulators of cellular metabolism in single smooth muscle cells from the rat femoral artery by using the whole cell patch-clamp technique. KATP current was not activated by exposure of cells to hypoxic solutions (Po2 ∼35 mmHg). In contrast, voltage-dependent calcium current and the depolarization-induced rise in intracellular calcium concentration ([Ca2+]i) was inhibited by hypoxia. Blocking mitochondrial ATP production by using the ATP synthase inhibitor oligomycin B (3 μM) did not activate current. Blocking glycolytic ATP production by using 2-deoxy-d-glucose (5 mM) also did not activate current. The protonophore carbonyl cyanide m-chlorophenylhydrazone (1 μM) depolarized the mitochondrial membrane potential and activated KATP current. This activation was reversed by oligomycin B, suggesting it occurred as a consequence of mitochondrial ATP consumption by ATP synthase working in reverse mode. Finally, anoxia induced by dithionite (0.5 mM) also depolarized the mitochondrial membrane potential and activated KATP current. Our data show that: 1) anoxia but not hypoxia activates KATP current in femoral artery myocytes; and 2) inhibition of cellular energy production is insufficient to activate KATP current and that energy consumption is required for current activation. These results suggest that vascular KATP channels are not activated during hypoxia via changes in cell metabolism. Furthermore, part of the relaxant effect of hypoxia on rat femoral artery may be mediated by changes in [Ca2+]i through modulation of calcium channel activity.

scholarly journals DDR1 Affects Metabolic Reprogramming in Breast Cancer Cells by Cross-Talking to the Insulin/IGF System

Biomolecules ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 926
Author(s):  
Veronica Vella ◽  
Marika Giuliano ◽  
Maria Luisa Nicolosi ◽  
Maria Giovanna Majorana ◽  
Małgorzata Anna Marć ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Breast Cancer Cells ◽  
Cell Metabolism ◽  
Growth Factor Receptor ◽  
Metabolic Reprogramming ◽  
Atp Production ◽  
Igf System ◽  
Putative Target ◽  
Collagen Receptor ◽  
Discoidin Domain Receptor 1

The insulin receptor isoform A (IR-A), a dual receptor for insulin and IGF2, plays a role in breast cancer (BC) progression and metabolic reprogramming. Notably, discoidin domain receptor 1 (DDR1), a collagen receptor often dysregulated in cancer, is involved in a functional crosstalk and feed forward loop with both the IR-A and the insulin like growth factor receptor 1 (IGF1R). Here, we aimed at investigating whether DDR1 might affect BC cell metabolism by modulating the IGF1R and/or the IR. To this aim, we generated MCF7 BC cells engineered to stably overexpress either IGF2 (MCF7/IGF2) or the IR-A (MCF7/IR-A). In both cell models, we observed that DDR1 silencing induced a significant decrease of total ATP production, particularly affecting the rate of mitochondrial ATP production. We also observed the downregulation of key molecules implicated in both glycolysis and oxidative phosphorylation. These metabolic changes were not modulated by DDR1 binding to collagen and occurred in part in the absence of IR/IGF1R phosphorylation. DDR1 silencing was ineffective in MCF7 knocked out for DDR1. Taken together, these results indicate that DDR1, acting in part independently of IR / IGF1R stimulation, might work as a novel regulator of BC metabolism and should be considered as putative target for therapy in BC.

scholarly journals Bioenergetic and metabolic impairments in Duchenne Muscular Dystrophy (DMD) patients' iPSC-derived cardiomyocytes

2020 ◽  
Vol 41 (Supplement_2) ◽  
Author(s):  
L Willi ◽  
B Agranovich ◽  
I Abramovich ◽  
D Freimark ◽  
M Arad ◽  
...  
Keyword(s):  
Stress Test ◽  
Young Male ◽  
Induced Pluripotent Stem Cell ◽  
Dystrophin Gene ◽  
Energy System ◽  
Basal Respiration ◽  
Mitochondrial Activity ◽  
Funding Source ◽  
Atp Production ◽  
Metabolic Impairments

Abstract Introduction DMD, an X-linked muscle degenerative fatal disease, is caused by mutations in the dystrophin gene. Dilated cardiomyopathy (DCM) is a major cause of morbidity and mortality in DMD patients. Treatments for DCM in DMD are limited to steroids and standard heart failure medications such as β-blockers and ACE-inhibitors, and therefore novel therapeutic modalities are urgently needed. Purpose We hypothesized that dystrophin mutations in DMD lead to cardiomyopathy-causing bioenergetic/metabolic impairments, which can be therapeutically targeted for improving cardiac function. Methods Induced Pluripotent Stem Cell-derived cardiomyocytes (iPSC-CMs) were generated from healthy volunteer and 3 DMD patients: young male (YM), adult male (AM) and adult female (AF). We investigated the bioenergetics, electrophysiology, mitochondrial and metabolic features of healthy and DMD iPSC-CMs using the Seahorse Flux analyzer, patch clamp, confocal fluorescence microscopy and Liquid chromatography mass spectrometry (LC-MS) technologies, respectively. Results To test the hypothesis, we measured respiration and glycolytic rates of healthy and DMD iPSC-CMs. Compared to healthy iPSC-CMs, in both AM and AF DMD, but not in YM DMD cardiomyocytes, there was a 75% decrease in ATP production, and 80% and 45% decrease in basal respiration, respectively. In agreement with the healthy-like bioenergetic status of YM, the iPSC-CMs showed no arrhythmias, in contrast to the prominent arrhythmias in AM and AF cardiomyocytes. To determine whether the impairment in the phosphorylation pathway (OXPHOS) affects glycolysis, we measured the cardiomyocytes' response to glycolytic stress test. These experiments showed that the glycolytic rates were similar in healthy and DMD iPSC-CMs. In agreement with impaired OXPHOS, mitochondrial activity measured by 3D life confocal microscopy was attenuated in the DMD male by 35%, compared to healthy cardiomyocytes. Furthermore, the metabolomic LC-MS analyses demonstrated significant differences in metabolite levels in YM, AM and AF DMD iPSC-CMs relative to healthy iPSC-CMs. For example, compared to healthy iPSC-CMs, there was a dramatic fall to undetected levels in phosphocreatine in both AM and AF, but not in YM DMD, indicating a dysfunctional phosphocreatine energy system. Conclusions DMD iPSC-CMs exhibit bioenergetic/metabolic impairments, which constitute novel targets for alleviating the cardiomyopathy in DMD patients. Funding Acknowledgement Type of funding source: Public grant(s) – National budget only. Main funding source(s): ISF - Israel Science Foundation

scholarly journals Neurotoxic Effect of Flavonol Myricetin in the Presence of Excess Copper

Molecules ◽  
2021 ◽  
Vol 26 (4) ◽  
pp. 845
Author(s):  
Anja Sadžak ◽  
Ignacija Vlašić ◽  
Zoran Kiralj ◽  
Marijana Batarelo ◽  
Nada Oršolić ◽  
...  
Keyword(s):  
Cell Death ◽  
Intracellular Signaling ◽  
Chromatin Condensation ◽  
Membrane Integrity ◽  
Toxic Effects ◽  
Trypan Blue Exclusion ◽  
Atp Production ◽  
Mtt Method ◽  
Biophysical Approach ◽  
Induced Changes

Oxidative stress (OS) induced by the disturbed homeostasis of metal ions is one of the pivotal factors contributing to neurodegeneration. The aim of the present study was to investigate the effects of flavonoid myricetin on copper-induced toxicity in neuroblastoma SH-SY5Y cells. As determined by the MTT method, trypan blue exclusion assay and measurement of ATP production, myricetin heightened the toxic effects of copper and exacerbated cell death. It also increased copper-induced generation of reactive oxygen species, indicating the prooxidative nature of its action. Furthermore, myricetin provoked chromatin condensation and loss of membrane integrity without caspase-3 activation, suggesting the activation of both caspase-independent programmed cell death and necrosis. At the protein level, myricetin-induced upregulation of PARP-1 and decreased expression of Bcl-2, whereas copper-induced changes in the expression of p53, p73, Bax and NME1 were not further affected by myricetin. Inhibitors of ERK1/2 and JNK kinases, protein kinase A and L-type calcium channels exacerbated the toxic effects of myricetin, indicating the involvement of intracellular signaling pathways in cell death. We also employed atomic force microscopy (AFM) to evaluate the morphological and mechanical properties of SH-SY5Y cells at the nanoscale. Consistent with the cellular and molecular methods, this biophysical approach also revealed a myricetin-induced increase in cell surface roughness and reduced elasticity. Taken together, we demonstrated the adverse effects of myricetin, pointing out that caution is required when considering powerful antioxidants for adjuvant therapy in copper-related neurodegeneration.

scholarly journals Plasma membrane integrity in health and disease: significance and therapeutic potential

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Catarina Dias ◽  
Jesper Nylandsted
Keyword(s):  
Plasma Membrane ◽  
Therapeutic Potential ◽  
Calcium Influx ◽  
Membrane Integrity ◽  
Cell Types ◽  
Physical Parameters ◽  
Membrane Repair ◽  
Plasma Membrane Integrity ◽  
Repair Mechanisms ◽  
And Function

AbstractMaintenance of plasma membrane integrity is essential for normal cell viability and function. Thus, robust membrane repair mechanisms have evolved to counteract the eminent threat of a torn plasma membrane. Different repair mechanisms and the bio-physical parameters required for efficient repair are now emerging from different research groups. However, less is known about when these mechanisms come into play. This review focuses on the existence of membrane disruptions and repair mechanisms in both physiological and pathological conditions, and across multiple cell types, albeit to different degrees. Fundamentally, irrespective of the source of membrane disruption, aberrant calcium influx is the common stimulus that activates the membrane repair response. Inadequate repair responses can tip the balance between physiology and pathology, highlighting the significance of plasma membrane integrity. For example, an over-activated repair response can promote cancer invasion, while the inability to efficiently repair membrane can drive neurodegeneration and muscular dystrophies. The interdisciplinary view explored here emphasises the widespread potential of targeting plasma membrane repair mechanisms for therapeutic purposes.

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