Faculty Opinions recommendation of Quantitation of mitochondrial dynamics by photolabeling of individual organelles shows that mitochondrial fusion is blocked during the Bax activation phase of apoptosis.

2004 ◽  
Author(s):  
David Andrews
Keyword(s):  
Mitochondrial Dynamics ◽  
Mitochondrial Fusion ◽  
Activation Phase

scholarly journals Quantitation of mitochondrial dynamics by photolabeling of individual organelles shows that mitochondrial fusion is blocked during the Bax activation phase of apoptosis

2004 ◽  
Vol 164 (4) ◽  
pp. 493-499 ◽  
Author(s):  
Mariusz Karbowski ◽  
Damien Arnoult ◽  
Hsiuchen Chen ◽  
David C. Chan ◽  
Carolyn L. Smith ◽  
...  
Keyword(s):  
Fluorescent Protein ◽  
Mitochondrial Dynamics ◽  
Dynamic Balance ◽  
Mitochondrial Fusion ◽  
Confocal Imaging ◽  
Time Range ◽  
Mitochondrial Morphology ◽  
Green Fluorescent ◽  
Mitochondrial Membrane Permeabilization ◽  
Activation Phase

A dynamic balance of organelle fusion and fission regulates mitochondrial morphology. During apoptosis this balance is altered, leading to an extensive fragmentation of the mitochondria. Here, we describe a novel assay of mitochondrial dynamics based on confocal imaging of cells expressing a mitochondrial matrix–targeted photoactivable green fluorescent protein that enables detection and quantification of organelle fusion in living cells. Using this assay, we visualize and quantitate mitochondrial fusion rates in healthy and apoptotic cells. During apoptosis, mitochondrial fusion is blocked independently of caspase activation. The block in mitochondrial fusion occurs within the same time range as Bax coalescence on the mitochondria and outer mitochondrial membrane permeabilization, and it may be a consequence of Bax/Bak activation during apoptosis.

scholarly journals Glucose limitation activates AMPK coupled SENP1-Sirt3 signalling in mitochondria for T cell memory development

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Jianli He ◽  
Xun Shangguan ◽  
Wei Zhou ◽  
Ying Cao ◽  
Quan Zheng ◽  
...  
Keyword(s):  
T Cell ◽  
Mitochondrial Dynamics ◽  
Mitochondrial Fusion ◽  
Metabolic Reprogramming ◽  
Negative Regulator ◽  
T Cell Memory ◽  
Memory Development ◽  
Cell Memory ◽  
Glucose Limitation ◽  
Glycolytic Intermediate

AbstractMetabolic programming and mitochondrial dynamics along with T cell differentiation affect T cell fate and memory development; however, how to control metabolic reprogramming and mitochondrial dynamics in T cell memory development is unclear. Here, we provide evidence that the SUMO protease SENP1 promotes T cell memory development via Sirt3 deSUMOylation. SENP1-Sirt3 signalling augments the deacetylase activity of Sirt3, promoting both OXPHOS and mitochondrial fusion. Mechanistically, SENP1 activates Sirt3 deacetylase activity in T cell mitochondria, leading to reduction of the acetylation of mitochondrial metalloprotease YME1L1. Consequently, deacetylation of YME1L1 suppresses its activity on OPA1 cleavage to facilitate mitochondrial fusion, which results in T cell survival and promotes T cell memory development. We also show that the glycolytic intermediate fructose-1,6-bisphosphate (FBP) as a negative regulator suppresses AMPK-mediated activation of the SENP1-Sirt3 axis and reduces memory development. Moreover, glucose limitation reduces FBP production and activates AMPK during T cell memory development. These data show that glucose limitation activates AMPK and the subsequent SENP1-Sirt3 signalling for T cell memory development.

scholarly journals When the Balance Tips: Dysregulation of Mitochondrial Dynamics as a Culprit in Disease

2021 ◽  
Vol 22 (9) ◽  
pp. 4617
Author(s):  
Styliana Kyriakoudi ◽  
Anthi Drousiotou ◽  
Petros P. Petrou
Keyword(s):  
Insulin Resistance ◽  
Mitochondrial Function ◽  
Human Disease ◽  
Molecular Mechanisms ◽  
Mitochondrial Dynamics ◽  
Mitochondrial Fusion ◽  
Mitochondrial Morphology ◽  
Disease Development ◽  
Pathological Conditions ◽  
Wide Range

Mitochondria are dynamic organelles, the morphology of which is tightly linked to their functions. The interplay between the coordinated events of fusion and fission that are collectively described as mitochondrial dynamics regulates mitochondrial morphology and adjusts mitochondrial function. Over the last few years, accruing evidence established a connection between dysregulated mitochondrial dynamics and disease development and progression. Defects in key components of the machinery mediating mitochondrial fusion and fission have been linked to a wide range of pathological conditions, such as insulin resistance and obesity, neurodegenerative diseases and cancer. Here, we provide an update on the molecular mechanisms promoting mitochondrial fusion and fission in mammals and discuss the emerging association of disturbed mitochondrial dynamics with human disease.

scholarly journals Interleukin-1β mediates alterations in mitochondrial fusion/fission proteins and memory impairment induced by amyloid-β oligomers

2021 ◽  
Vol 18 (1) ◽  
Author(s):  
Andre F. Batista ◽  
Tayná Rody ◽  
Leticia Forny-Germano ◽  
Suzana Cerdeiro ◽  
Maria Bellio ◽  
...  
Keyword(s):  
Cognitive Impairment ◽  
Mitochondrial Dysfunction ◽  
Memory Impairment ◽  
Mitochondrial Dynamics ◽  
Interleukin 1 ◽  
Amyloid Β ◽  
Mitochondrial Fusion ◽  
Synapse Loss ◽  
Cynomolgus Macaques ◽  
The Impact

Abstract Background The lack of effective treatments for Alzheimer’s disease (AD) reflects an incomplete understanding of disease mechanisms. Alterations in proteins involved in mitochondrial dynamics, an essential process for mitochondrial integrity and function, have been reported in AD brains. Impaired mitochondrial dynamics causes mitochondrial dysfunction and has been associated with cognitive impairment in AD. Here, we investigated a possible link between pro-inflammatory interleukin-1 (IL-1), mitochondrial dysfunction, and cognitive impairment in AD models. Methods We exposed primary hippocampal cell cultures to amyloid-β oligomers (AβOs) and carried out AβO infusions into the lateral cerebral ventricle of cynomolgus macaques to assess the impact of AβOs on proteins that regulate mitochondrial dynamics. Where indicated, primary cultures were pre-treated with mitochondrial division inhibitor 1 (mdivi-1), or with anakinra, a recombinant interleukin-1 receptor (IL-1R) antagonist used in the treatment of rheumatoid arthritis. Cognitive impairment was investigated in C57BL/6 mice that received an intracerebroventricular (i.c.v.) infusion of AβOs in the presence or absence of mdivi-1. To assess the role of interleukin-1 beta (IL-1β) in AβO-induced alterations in mitochondrial proteins and memory impairment, interleukin receptor-1 knockout (Il1r1−/−) mice received an i.c.v. infusion of AβOs. Results We report that anakinra prevented AβO-induced alteration in mitochondrial dynamics proteins in primary hippocampal cultures. Altered levels of proteins involved in mitochondrial fusion and fission were observed in the brains of cynomolgus macaques that received i.c.v. infusions of AβOs. The mitochondrial fission inhibitor, mdivi-1, alleviated synapse loss and cognitive impairment induced by AβOs in mice. In addition, AβOs failed to cause alterations in expression of mitochondrial dynamics proteins or memory impairment in Il1r1−/− mice. Conclusion These findings indicate that IL-1β mediates the impact of AβOs on proteins involved in mitochondrial dynamics and that strategies aimed to prevent pathological alterations in those proteins may counteract synapse loss and cognitive impairment in AD.

scholarly journals Dynamin-related protein 1 deficiency accelerates lipopolysaccharide-induced acute liver injury and inflammation in mice

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Lixiang Wang ◽  
Xin Li ◽  
Yuki Hanada ◽  
Nao Hasuzawa ◽  
Yoshinori Moriyama ◽  
...  
Keyword(s):  
Liver Disease ◽  
Liver Injury ◽  
Er Stress ◽  
Disease Progression ◽  
Acute Liver Injury ◽  
Mitochondrial Dynamics ◽  
Mitochondrial Fission ◽  
Mitochondrial Fusion ◽  
Related Protein ◽  
Liver Disease Progression

AbstractMitochondrial fusion and fission, which are strongly related to normal mitochondrial function, are referred to as mitochondrial dynamics. Mitochondrial fusion defects in the liver cause a non-alcoholic steatohepatitis-like phenotype and liver cancer. However, whether mitochondrial fission defect directly impair liver function and stimulate liver disease progression, too, is unclear. Dynamin-related protein 1 (DRP1) is a key factor controlling mitochondrial fission. We hypothesized that DRP1 defects are a causal factor directly involved in liver disease development and stimulate liver disease progression. Drp1 defects directly promoted endoplasmic reticulum (ER) stress, hepatocyte death, and subsequently induced infiltration of inflammatory macrophages. Drp1 deletion increased the expression of numerous genes involved in the immune response and DNA damage in Drp1LiKO mouse primary hepatocytes. We administered lipopolysaccharide (LPS) to liver-specific Drp1-knockout (Drp1LiKO) mice and observed an increased inflammatory cytokine expression in the liver and serum caused by exaggerated ER stress and enhanced inflammasome activation. This study indicates that Drp1 defect-induced mitochondrial dynamics dysfunction directly regulates the fate and function of hepatocytes and enhances LPS-induced acute liver injury in vivo.

scholarly journals Mitochondrial fusion mediated by mitofusin 1 regulates macrophage mycobactericidal activity by enhancing autophagy

2021 ◽  
Author(s):  
Yuping Ning ◽  
Yi Cai ◽  
Youchao Dai ◽  
Fuxiang Li ◽  
Siwei Mo ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Life Cycle ◽  
Atp Synthase ◽  
Host Defense ◽  
Mitochondrial Dynamics ◽  
Critical Role ◽  
Mitochondrial Fusion ◽  
Atp Production ◽  
Metabolism Pathway ◽  
Mitofusin 1

Mitochondria as a highly dynamic organelle continuously changes morphology and position during its life cycle. Mitochondrial dynamics including fission and fusion play a critical role in maintaining functional mitochondria for ATP production, which is directly linked to host defense against Mtb infection. However, how macrophages regulate mitochondrial dynamics during Mycobacterium tuberculosis (Mtb) infection remains elusive. In this study, we found that Mtb infection induced mitochondrial fusion through enhancing the expression of mitofusin 1 ( MFN1 ), which resulted in increased ATP production. Silencing MFN1 inhibited mitochondrial fusion and subsequently reduced ATP production, which, in turn, severely impaired macrophages mycobactericidal activity by inhibiting autophagy. Impairment of mycobactericidal activity and autophagy was replicated using oligomycin, an inhibitor of ATP synthase. In summary, our study revealed MFN1-mediated mitochondrial fusion is essential for macrophages mycobactericidal activity through the regulation of ATP dependent autophagy. MFN1-mediated metabolism pathway might be targets for development of host direct therapy (HDT) strategy against TB.

The modified mitochondrial outer membrane carrier MTCH2 links mitochondrial fusion to lipogenesis

2021 ◽  
Vol 220 (11) ◽  
Author(s):  
Katherine Labbé ◽  
Shona Mookerjee ◽  
Maxence Le Vasseur ◽  
Eddy Gibbs ◽  
Chad Lerner ◽  
...  
Keyword(s):  
Lipid Metabolism ◽  
Mitochondrial Dynamics ◽  
Mitochondrial Fusion ◽  
Mitochondrial Outer Membrane ◽  
Mitochondrial Carrier ◽  
Cellular Survival ◽  
Mitochondrial Elongation ◽  
Specific Lipid

Mitochondrial function is integrated with cellular status through the regulation of opposing mitochondrial fusion and division events. Here we uncover a link between mitochondrial dynamics and lipid metabolism by examining the cellular role of mitochondrial carrier homologue 2 (MTCH2). MTCH2 is a modified outer mitochondrial membrane carrier protein implicated in intrinsic cell death and in the in vivo regulation of fatty acid metabolism. Our data indicate that MTCH2 is a selective effector of starvation-induced mitochondrial hyperfusion, a cytoprotective response to nutrient deprivation. We find that MTCH2 stimulates mitochondrial fusion in a manner dependent on the bioactive lipogenesis intermediate lysophosphatidic acid. We propose that MTCH2 monitors flux through the lipogenesis pathway and transmits this information to the mitochondrial fusion machinery to promote mitochondrial elongation, enhanced energy production, and cellular survival under homeostatic and starvation conditions. These findings will help resolve the roles of MTCH2 and mitochondria in tissue-specific lipid metabolism in animals.

scholarly journals Mitochondrial Fusion by M1 Promotes Embryoid Body Cardiac Differentiation of Human Pluripotent Stem Cells

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Jarmon G. Lees ◽  
Anne M. Kong ◽  
Yi C. Chen ◽  
Priyadharshini Sivakumaran ◽  
Damián Hernández ◽  
...  
Keyword(s):  
Stem Cells ◽  
Pluripotent Stem Cells ◽  
Embryoid Body ◽  
Mitochondrial Dynamics ◽  
Embryoid Bodies ◽  
Mitochondrial Fusion ◽  
Cardiac Differentiation ◽  
Patient Specific ◽  
Mitochondrial Morphology ◽  
Human Ipscs

Human induced pluripotent stem cells (iPSCs) can be differentiated in vitro into bona fide cardiomyocytes for disease modelling and personalized medicine. Mitochondrial morphology and metabolism change dramatically as iPSCs differentiate into mesodermal cardiac lineages. Inhibiting mitochondrial fission has been shown to promote cardiac differentiation of iPSCs. However, the effect of hydrazone M1, a small molecule that promotes mitochondrial fusion, on cardiac mesodermal commitment of human iPSCs is unknown. Here, we demonstrate that treatment with M1 promoted mitochondrial fusion in human iPSCs. Treatment of iPSCs with M1 during embryoid body formation significantly increased the percentage of beating embryoid bodies and expression of cardiac-specific genes. The pro-fusion and pro-cardiogenic effects of M1 were not associated with changes in expression of the α and β subunits of adenosine triphosphate (ATP) synthase. Our findings demonstrate for the first time that hydrazone M1 is capable of promoting cardiac differentiation of human iPSCs, highlighting the important role of mitochondrial dynamics in cardiac mesoderm lineage specification and cardiac development. M1 and other mitochondrial fusion promoters emerge as promising molecular targets to generate lineages of the heart from human iPSCs for patient-specific regenerative medicine.

scholarly journals T-2 Toxin-Induced Oxidative Stress Leads to Imbalance of Mitochondrial Fission and Fusion to Activate Cellular Apoptosis in the Human Liver 7702 Cell Line

Toxins ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 43 ◽  
Author(s):  
Junhua Yang ◽  
Wenbo Guo ◽  
Jianhua Wang ◽  
Xianli Yang ◽  
Zhiqi Zhang ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Cell Apoptosis ◽  
Human Liver ◽  
Mitochondrial Dynamics ◽  
Mitochondrial Fission ◽  
Mitochondrial Fusion ◽  
Mitochondrial Dynamic ◽  
Normal Human Liver ◽  
Induced Apoptosis

T-2 toxin, as a highly toxic mycotoxin to humans and animals, induces oxidative stress and apoptosis in various cells and tissues. Apoptosis and mitochondrial fusion/fission are two tightly interconnected processes that are crucial for maintaining physiological homeostasis. However, the role of mitochondrial fusion/fission in apoptosis of T-2 toxin remains unknown. Hence, we aimed to explore the putative role of mitochondrial fusion/fission on T-2 toxin induced apoptosis in normal human liver (HL-7702) cells. T-2 toxin treatment (0, 0.1, 1.0, or 10 μg/L) for 24 h caused decreased cell viability and ATP concentration and increased production of (ROS), as seen by a loss of mitochondrial membrane potential (∆Ψm) and increase in mitochondrial fragmentation. Subsequently, the mitochondrial dynamic imbalance was activated, evidenced by a dose-dependent decrease and increase in the protein expression of mitochondrial fusion (OPA1, Mfn1, and Mfn2) and fission (Drp1 and Fis1), respectively. Furthermore, the T-2 toxin promoted the release of cytochrome c from mitochondria to cytoplasm and induced cell apoptosis triggered by upregulation of Bax and Bax/Bcl-2 ratios, and further activated the caspase pathways. Taken together, these results indicate that altered mitochondrial dynamics induced by oxidative stress with T-2 toxin exposure likely contribute to mitochondrial injury and HL-7702 cell apoptosis.

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