scholarly journals Mitochondrial dynamics: overview of molecular mechanisms

2018 ◽  
Vol 62 (3) ◽  
pp. 341-360 ◽  
Author(s):  
Lisa Tilokani ◽  
Shun Nagashima ◽  
Vincent Paupe ◽  
Julien Prudent
Keyword(s):  
Membrane Fusion ◽  
Mitochondrial Membrane ◽  
Molecular Mechanisms ◽  
Calcium Influx ◽  
Mitochondrial Dynamics ◽  
Mitochondrial Fission ◽  
Membrane Lipid ◽  
Inner Mitochondrial Membrane ◽  
Step Process ◽  
Shape Distribution

Mitochondria are highly dynamic organelles undergoing coordinated cycles of fission and fusion, referred as ‘mitochondrial dynamics’, in order to maintain their shape, distribution and size. Their transient and rapid morphological adaptations are crucial for many cellular processes such as cell cycle, immunity, apoptosis and mitochondrial quality control. Mutations in the core machinery components and defects in mitochondrial dynamics have been associated with numerous human diseases. These dynamic transitions are mainly ensured by large GTPases belonging to the Dynamin family. Mitochondrial fission is a multi-step process allowing the division of one mitochondrion in two daughter mitochondria. It is regulated by the recruitment of the GTPase Dynamin-related protein 1 (Drp1) by adaptors at actin- and endoplasmic reticulum-mediated mitochondrial constriction sites. Drp1 oligomerization followed by mitochondrial constriction leads to the recruitment of Dynamin 2 to terminate membrane scission. Inner mitochondrial membrane constriction has been proposed to be an independent process regulated by calcium influx. Mitochondrial fusion is driven by a two-step process with the outer mitochondrial membrane fusion mediated by mitofusins 1 and 2 followed by inner membrane fusion, mediated by optic atrophy 1. In addition to the role of membrane lipid composition, several members of the machinery can undergo post-translational modifications modulating these processes. Understanding the molecular mechanisms controlling mitochondrial dynamics is crucial to decipher how mitochondrial shape meets the function and to increase the knowledge on the molecular basis of diseases associated with morphology defects. This article will describe an overview of the molecular mechanisms that govern mitochondrial fission and fusion in mammals.

scholarly journals Mitochondrial Aurora kinase A induces mitophagy by interacting with MAP1LC3 and Prohibitin 2

2021 ◽  
Vol 4 (6) ◽  
pp. e202000806
Author(s):  
Giulia Bertolin ◽  
Marie-Clotilde Alves-Guerra ◽  
Angélique Cheron ◽  
Agnès Burel ◽  
Claude Prigent ◽  
...  
Keyword(s):  
Mitochondrial Membrane ◽  
Molecular Mechanisms ◽  
Mitochondrial Dynamics ◽  
Aurora Kinase ◽  
Inner Mitochondrial Membrane ◽  
Serine Threonine Kinase ◽  
Independent Manner ◽  
Atp Production ◽  
Core Components ◽  
Autophagy Pathway

Epithelial and haematologic tumours often show the overexpression of the serine/threonine kinase AURKA. Recently, AURKA was shown to localise at mitochondria, where it regulates mitochondrial dynamics and ATP production. Here we define the molecular mechanisms of AURKA in regulating mitochondrial turnover by mitophagy. AURKA triggers the degradation of Inner Mitochondrial Membrane/matrix proteins by interacting with core components of the autophagy pathway. On the inner mitochondrial membrane, the kinase forms a tripartite complex with MAP1LC3 and the mitophagy receptor PHB2, which triggers mitophagy in a PARK2/Parkin–independent manner. The formation of the tripartite complex is induced by the phosphorylation of PHB2 on Ser39, which is required for MAP1LC3 to interact with PHB2. Last, treatment with the PHB2 ligand xanthohumol blocks AURKA-induced mitophagy by destabilising the tripartite complex and restores normal ATP production levels. Altogether, these data provide evidence for a role of AURKA in promoting mitophagy through the interaction with PHB2 and MAP1LC3. This work paves the way to the use of function-specific pharmacological inhibitors to counteract the effects of the overexpression of AURKA in cancer.

scholarly journals Mitochondrial Aurora kinase A induces mitophagy by interacting with MAP1LC3 and Prohibitin 2

2020 ◽  
Author(s):  
Giulia Bertolin ◽  
Marie-Clotilde Alves-Guerra ◽  
Agnès Burel ◽  
Claude Prigent ◽  
Roland Le Borgne ◽  
...  
Keyword(s):  
Mitochondrial Membrane ◽  
Molecular Mechanisms ◽  
Mitochondrial Dynamics ◽  
Aurora Kinase ◽  
Dependent Manner ◽  
Inner Mitochondrial Membrane ◽  
Serine Threonine Kinase ◽  
Independent Manner ◽  
Atp Production ◽  
Core Components

AbstractEpithelial and haematologic tumours often show the overexpression of the serine/threonine kinase AURKA. Recently, AURKA was shown to localise at mitochondria, where it regulates mitochondrial dynamics and ATP production. Here we define the molecular mechanisms of AURKA in regulating mitochondrial turnover by mitophagy. When overexpressed, AURKA induces the rupture of the Outer Mitochondrial Membrane in a proteasome-dependent manner. Then, AURKA triggers the degradation of Inner Mitochondrial Membrane (IMM)/matrix proteins by interacting with core components of the autophagy pathway. On the IMM, the kinase forms a tripartite complex with MAP1LC3 and the mitophagy receptor PHB2. This complex is necessary to trigger mitophagy in a PARK2/Parkin-independent manner. The formation of the tripartite complex is induced by the phosphorylation of PHB2 on Ser39, which is required for MAP1LC3 to interact with PHB2. Last, treatment with the PHB2 ligand Xanthohumol blocks AURKA-induced mitophagy by destabilising the tripartite complex. This treatment also restores normal ATP production levels. Altogether, these data provide evidence for a previously undetected role of AURKA in promoting mitophagy through the interaction with PHB2 and MAP1LC3. This work paves the way to the use of function-specific pharmacological inhibitors to counteract the effects of the overexpression of AURKA in cancer.

Abstract 5379: Increased Myocardial Fatty Acid Uptake by Acyl-CoA Synthetase 1 Impairs Mitochondrial Function and Dynamics

Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
Heiko Bugger ◽  
Xiao Xuan Hu ◽  
Joseph Tuinei ◽  
Heather Theobald ◽  
William L Holland ◽  
...  
Keyword(s):  
Mitochondrial Dysfunction ◽  
Mitochondrial Membrane ◽  
Morphological Changes ◽  
Mitochondrial Dynamics ◽  
Mitochondrial Fission ◽  
Atp Synthesis ◽  
Fatty Acid Uptake ◽  
Membrane Lipid ◽  
Acid Uptake

Increased uptake and oxidation of fatty acids (FA) in diabetic hearts may contribute to mitochondrial dysfunction by promoting oxidative stress. To test this hypothesis, we investigated mice with cardiomyocyte-restricted overexpression of long-chain acyl-CoA synthetase 1 (MHC-ACS). In vivo PET studies revealed increased myocardial FA uptake (+120%; p<0.05) in MHC-ACS. Unexpectedly, FA oxidation and myocellular triglyceride content were unchanged, and PPARα-regulated FAO genes and PGC-1α-regulated OXPHOS genes were unaltered. However, cardiac content of the phospholipid precursors ceramide (+260%; p<0.05) and diacylglycerol (+40%; p<0.05) were increased. Mitochondrial cardiolipin content was decreased (−25%; p<0.05) and remodeled with substitution of 18:2 FA chains by unsaturated 22:6 FAs. Both ADP-stimulated mitochondrial O2 consumption (14.3±0.9 vs. 16.8±0.5 nmol/min/mgdw; p<0.05) and ATP synthesis (24.2±1.4 vs. 31.8±1.6 nmol/min/mgdw; p<0.05) were decreased in MHC-ACS in saponin-permeabilized cardiac fibers using palmitoyl-carnitine as a substrate. Mitochondrial superoxide production was increased by 75% (p<0.05). Electron microscopy in 3 to 24 week-old mice revealed increased mitochondrial number, which was highest at 3 weeks (3wk +210%, 12wk +120%, 24wk +130%; all p<0.05), and reduced mitochondrial size. Translocation of the mitochondrial fission protein dynamin-related protein 1 (Drp1) from cytosol to mitochondria was absent (p<0.05) in MHC-ACS, but not in controls. Mitochondrial membrane content of the fission protein fission 1 and the fusion proteins mitofusin 1 and 2 were unchanged. These morphological changes are consistent with increased mitochondrial fission and reduced Drp1 likely represents an adaptive response. Thus remodeling of the myocardial lipid pool and mitochondrial membrane lipid composition are associated with impaired mitochondrial dynamics and represents a novel mechanism for lipid-induced mitochondrial dysfunction in the heart.

scholarly journals Two distinct actin filament populations have effects on mitochondria, with differences in stimuli and assembly factors

2019 ◽  
Author(s):  
Tak Shun Fung ◽  
Wei-Ke Ji ◽  
Henry N. Higgs ◽  
Rajarshi Chakrabarti
Keyword(s):  
Mitochondrial Membrane ◽  
Actin Polymerization ◽  
Mitochondrial Dynamics ◽  
Mitochondrial Fission ◽  
Actin Assembly ◽  
Mitochondrial Depolarization ◽  
Inner Mitochondrial Membrane ◽  
Cytoplasmic Actin ◽  
Summary Statement ◽  
Shape Changes

AbstractRecent studies show that mitochondria and actin filaments work together in two contexts: 1) increased cytoplasmic calcium induces cytoplasmic actin polymerization that stimulates mitochondrial fission, and 2) mitochondrial depolarization causes actin assembly around mitochondria, with roles in mitophagy. It is unclear whether these two processes utilize similar actin assembly mechanisms. Here, we show that these are distinct actin assembly mechanisms in the acute phase after treatment (<10 min). Calcium-induced actin assembly is INF2-dependent and Arp2/3 complex-independent, whereas depolarization-induced actin assembly is Arp2/3 complex-dependent and INF2-independent. The two types of actin polymerization are morphologically distinct, with calcium-induced filaments throughout the cytosol and depolarization-induced filaments as “clouds” around depolarized mitochondria. We have previously shown that calcium-induced actin stimulates increases in both mitochondrial calcium and recruitment of the dynamin GTPase Drp1. In contrast, depolarization-induced actin is temporally-associated with extensive mitochondrial dynamics that do not result in mitochondrial fission, but in circularization of the inner mitochondrial membrane (IMM). These dynamics are dependent upon the protease Oma1 and independent of Drp1. Actin cloud inhibition causes increased IMM circularization, suggesting that actin clouds limit these dynamics.Summary statementMitochondrial depolarization induces Arp2/3 complex-dependent actin clouds that restrain mitochondrial shape changes induced by Oma1 on the inner mitochondrial membrane. A distinct actin network stimulates mitochondrial fission in response to calcium.

scholarly journals Acrolein Aggravates Secondary Brain Injury After Intracerebral Hemorrhage Through Drp1-Mediated Mitochondrial Oxidative Damage in Mice

2020 ◽  
Vol 36 (10) ◽  
pp. 1158-1170
Author(s):  
Xun Wu ◽  
Wenxing Cui ◽  
Wei Guo ◽  
Haixiao Liu ◽  
Jianing Luo ◽  
...  
Keyword(s):  
Brain Injury ◽  
Oxidative Damage ◽  
Mitochondrial Membrane ◽  
Molecular Mechanisms ◽  
Mitochondrial Fission ◽  
Secondary Brain Injury ◽  
Functional Deficits ◽  
Highly Active ◽  
Neural Apoptosis ◽  
Mitochondrial Oxidative Damage

Abstract Clinical advances in the treatment of intracranial hemorrhage (ICH) are restricted by the incomplete understanding of the molecular mechanisms contributing to secondary brain injury. Acrolein is a highly active unsaturated aldehyde which has been implicated in many nervous system diseases. Our results indicated a significant increase in the level of acrolein after ICH in mouse brain. In primary neurons, acrolein induced an increase in mitochondrial fragmentation, loss of mitochondrial membrane potential, generation of reactive oxidative species, and release of mitochondrial cytochrome c. Mechanistically, acrolein facilitated the translocation of dynamin-related protein1 (Drp1) from the cytoplasm onto the mitochondrial membrane and led to excessive mitochondrial fission. Further studies found that treatment with hydralazine (an acrolein scavenger) significantly reversed Drp1 translocation and the morphological damage of mitochondria after ICH. In parallel, the neural apoptosis, brain edema, and neurological functional deficits induced by ICH were also remarkably alleviated. In conclusion, our results identify acrolein as an important contributor to the secondary brain injury following ICH. Meanwhile, we uncovered a novel mechanism by which Drp1-mediated mitochondrial oxidative damage is involved in acrolein-induced brain injury.

scholarly journals TRPC6-Mediated ERK1/2 Activation Increases Dentate Granule Cell Resistance to Status Epilepticus Via Regulating Lon Protease-1 Expression and Mitochondrial Dynamics

Cells ◽  
2019 ◽  
Vol 8 (11) ◽  
pp. 1376 ◽  
Author(s):  
Kim ◽  
Park ◽  
Choi ◽  
Kong ◽  
Kang
Keyword(s):  
Status Epilepticus ◽  
Granule Cell ◽  
Molecular Mechanisms ◽  
Transient Receptor Potential ◽  
Mitochondrial Dynamics ◽  
Neurological Diseases ◽  
Mitochondrial Fission ◽  
Receptor Potential ◽  
Lon Protease ◽  
Dentate Granule Cell

Transient receptor potential canonical channel-6 (TRPC6) is one of the Ca2+-permeable non-selective cation channels. TRPC6 is mainly expressed in dentate granule cell (DGC), which is one of the most resistant neuronal populations to various harmful stresses. Although TRPC6 knockdown evokes the massive DGC degeneration induced by status epilepticus (a prolonged seizure activity, SE), the molecular mechanisms underlying the role of TRPC6 in DGC viability in response to SE are still unclear. In the present study, hyperforin (a TRPC6 activator) facilitated mitochondrial fission in DGC concomitant with increases in Lon protease-1 (LONP1, a mitochondrial protease) expression and extracellular-signal-regulated kinase 1/2 (ERK1/2) phosphorylation under physiological conditions, which were abrogated by U0126 (an ERK1/2 inhibitor) co-treatment. TRPC6 knockdown showed the opposite effects on LONP1 expression, ERK1/2 activity, and mitochondrial dynamics. In addition, TRPC6 siRNA and U0126 evoked the massive DGC degeneration accompanied by mitochondrial elongation following SE, independent of seizure severity. However, LONP1 siRNA exacerbated SE-induced DGC death without affecting mitochondrial length. These findings indicate that TRPC6-ERK1/2 activation may increase DGC invulnerability to SE by regulating LONP1 expression as well as mitochondrial dynamics. Therefore, TRPC6-ERK1/2-LONP1 signaling pathway will be an interesting and important therapeutic target for neuroprotection from various neurological diseases.

scholarly journals Mitochondrial respiratory chain inhibitors modulate the metal-induced inner mitochondrial membrane permeabilization.

2010 ◽  
Vol 57 (4) ◽  
Author(s):  
Elena A Belyaeva
Keyword(s):  
Heavy Metal ◽  
Mitochondrial Membrane ◽  
Molecular Mechanisms ◽  
Protective Action ◽  
Membrane Permeabilization ◽  
Mitochondrial Swelling ◽  
Complex Iii ◽  
Rat Liver Mitochondria ◽  
Inner Mitochondrial Membrane ◽  
Mitochondrial Membrane Permeabilization

To elucidate the molecular mechanisms of the protective action of stigmatellin (an inhibitor of complex III of mitochondrial electron transport chain, mtETC) against the heavy metal-induced cytotoxicity, we tested its effectiveness against mitochondrial membrane permeabilization produced by heavy metal ions Cd²(+), Hg²(+), Cu²(+) and Zn²(+), as well as by Ca²(+) (in the presence of P(i)) or Se (in form of Na₂SeO₃) using isolated rat liver mitochondria. It was shown that stigmatellin modulated mitochondrial swelling produced by these metals/metalloids in the isotonic sucrose medium in the presence of ascorbate plus tetramethyl-p-phenylenediamine (complex IV substrates added for energization of the mitochondria). It was found that stigmatellin and other mtETC inhibitors enhanced the mitochondrial swelling induced by selenite. However, in the same medium, all the mtETC inhibitors tested as well as cyclosporin A and bongkrekic acid did not significantly affect Cu²(+)-induced swelling. In contrast, the high-amplitude swelling produced by Cd²(+), Hg²(+), Zn²(+), or Ca²(+) plus P(i) was significantly depressed by these inhibitors. Significant differences in the action of these metals/metalloids on the redox status of pyridine nucleotides, transmembrane potential and mitochondrial respiration were also observed. In the light of these results as well as the data from the recent literature, our hypothesis on a possible involvement of the respiratory supercomplex, formed by complex I (P-site) and complex III (S-site) in the mitochondrial permeabilization mediated by the mitochondrial transition pore, is updated.

scholarly journals Mitochondrial dynamics and mitophagy are necessary for proper invasive growth in Rice Blast

2019 ◽  
Author(s):  
Yanjun Kou ◽  
Yunlong He ◽  
Jiehua Qiu ◽  
Shu Yazhou ◽  
Fan Yang ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Morphological Changes ◽  
Mitochondrial Dynamics ◽  
Mitochondrial Fission ◽  
Blast Disease ◽  
Cereal Crops ◽  
Mitochondrial Morphology ◽  
Invasive Growth ◽  
In Planta ◽  
Antioxidant Treatment

SUMMARYMagnaporthe oryzaecauses Blast disease, which is one of the most devastating infections in rice and several important cereal crops.M. oryzaeneeds to coordinate gene regulation, morphological changes, nutrient acquisition, and host evasion, in order to invade and proliferate within the plant tissues. Thus far, the molecular mechanisms underlying the regulation of invasive growthin plantahave remained largely unknown. We identified a precise filamentous-punctate-filamentous cycle in mitochondrial morphology duringMagnaporthe-Rice interaction. Interestingly, loss of either the mitochondrial fusion (MoFzo1) or fission (MoDnm1) machinery, or inhibition of mitochondrial fission using Mdivi-1 caused significant reduction inM. oryzaepathogenicity. Furthermore, exogenous carbon source(s) but not antioxidant treatment delayed such mitochondrial dynamics/transition during invasive growth. Such nutrient-based regulation of organellar dynamics preceded MoAtg24-mediated mitophagy, which was found to be essential for proper biotrophic development and invasive growthin planta. We propose that precise mitochondrial dynamics and mitophagy occur during the transition from biotrophy to necrotrophy, and are required for proper induction and establishment of the blast disease in rice.

scholarly journals Metabolic Alterations Caused by Defective Cardiolipin Remodeling in Inherited Cardiomyopathies

Life ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 277
Author(s):  
Christina Wasmus ◽  
Jan Dudek
Keyword(s):  
Heart Failure ◽  
Respiratory Chain ◽  
Mitochondrial Membrane ◽  
Molecular Mechanisms ◽  
Mitochondrial Enzymes ◽  
Inner Mitochondrial Membrane ◽  
Mitochondrial Functions ◽  
Metabolic Remodeling ◽  
Inherited Cardiomyopathies ◽  
The Impact

The heart is the most energy-consuming organ in the human body. In heart failure, the homeostasis of energy supply and demand is endangered by an increase in cardiomyocyte workload, or by an insufficiency in energy-providing processes. Energy metabolism is directly associated with mitochondrial redox homeostasis. The production of toxic reactive oxygen species (ROS) may overwhelm mitochondrial and cellular ROS defense mechanisms in case of heart failure. Mitochondria are essential cell organelles and provide 95% of the required energy in the heart. Metabolic remodeling, changes in mitochondrial structure or function, and alterations in mitochondrial calcium signaling diminish mitochondrial energy provision in many forms of cardiomyopathy. The mitochondrial respiratory chain creates a proton gradient across the inner mitochondrial membrane, which couples respiration with oxidative phosphorylation and the preservation of energy in the chemical bonds of ATP. Akin to other mitochondrial enzymes, the respiratory chain is integrated into the inner mitochondrial membrane. The tight association with the mitochondrial phospholipid cardiolipin (CL) ensures its structural integrity and coordinates enzymatic activity. This review focuses on how changes in mitochondrial CL may be associated with heart failure. Dysfunctional CL has been found in diabetic cardiomyopathy, ischemia reperfusion injury and the aging heart. Barth syndrome (BTHS) is caused by an inherited defect in the biosynthesis of cardiolipin. Moreover, a dysfunctional CL pool causes other types of rare inherited cardiomyopathies, such as Sengers syndrome and Dilated Cardiomyopathy with Ataxia (DCMA). Here we review the impact of cardiolipin deficiency on mitochondrial functions in cellular and animal models. We describe the molecular mechanisms concerning mitochondrial dysfunction as an incitement of cardiomyopathy and discuss potential therapeutic strategies.

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