scholarly journals HSPA9/Mortalin mediates axo-protection and modulates mitochondrial dynamics in neurons

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Cécile A. Ferré ◽  
Anne Thouard ◽  
Alexandre Bétourné ◽  
Anne-Louise Le Dorze ◽  
Pascale Belenguer ◽  
...  
Keyword(s):  
Mitochondrial Dynamics ◽  
Mitochondrial Morphology ◽  
Neuronal Cultures ◽  
Mitochondrial Fragmentation ◽  
Primary Neuronal Cultures ◽  
Over Expression ◽  
Neuronal Fate ◽  
Axonal Compartment ◽  
Neuronal Stress ◽  
Rotenone Exposure

AbstractMortalin is a mitochondrial chaperone protein involved in quality control of proteins imported into the mitochondrial matrix, which was recently described as a sensor of neuronal stress. Mortalin is down-regulated in neurons of patients with neurodegenerative diseases and levels of Mortalin expression are correlated with neuronal fate in animal models of Alzheimer's disease or cerebral ischemia. To date, however, the links between Mortalin levels, its impact on mitochondrial function and morphology and, ultimately, the initiation of neurodegeneration, are still unclear. In the present study, we used lentiviral vectors to over- or under-express Mortalin in primary neuronal cultures. We first analyzed the early events of neurodegeneration in the axonal compartment, using oriented neuronal cultures grown in microfluidic-based devices. We observed that Mortalin down-regulation induced mitochondrial fragmentation and axonal damage, whereas its over-expression conferred protection against axonal degeneration mediated by rotenone exposure. We next demonstrated that Mortalin levels modulated mitochondrial morphology by acting on DRP1 phosphorylation, thereby further illustrating the crucial implication of mitochondrial dynamics on neuronal fate in degenerative diseases.

scholarly journals HSPA9/Mortalin Mediates Axo-Protection by Modulating Mitochondrial Dynamics in Neurons

2020 ◽  
Author(s):  
Cécile Ferré ◽  
Anne Thouard ◽  
Alexandre Bétourné ◽  
Pascale Belenguer ◽  
Marie-Christine Miquel ◽  
...  
Keyword(s):  
Mitochondrial Dynamics ◽  
Direct Action ◽  
Mitochondrial Morphology ◽  
Neuronal Cultures ◽  
Mitochondrial Fragmentation ◽  
Primary Neuronal Cultures ◽  
Over Expression ◽  
Neuronal Fate ◽  
Axonal Compartment ◽  
Neuronal Stress

Abstract Mortalin is a mitochondrial chaperone protein involved in quality control of proteins imported into the mitochondrial matrix, which was recently described as a sensor of neuronal stress. Mortalin is down-regulated in neurons of patients with neurodegenerative diseases and levels of Mortalin expression are correlated with neuronal fate in animal models of Alzheimer's disease or cerebral ischemia. To date, however, the links between Mortalin levels, its impact on mitochondrial function and morphology and, ultimately, the initiation of neurodegeneration, are still unclear. In the present study, we used lentiviral vectors to over- or under-express Mortalin in primary neuronal cultures. We first analyzed the early events of neurodegeneration in the axonal compartment, using oriented neuronal cultures grown in microfluidic-based devices. We observed that Mortalin down-regulation induced mitochondrial fragmentation and axonal damage, whereas its over-expression conferred protection against axonal degeneration mediated by oxidative stress. We next demonstrated that Mortalin levels modulated mitochondrial morphology by a direct action on DRP1 phosphorylation, thereby further illustrating the crucial implication of mitochondrial dynamics on neuronal fate in degenerative diseases.

scholarly journals Mitochondrial fission and mitophagy are independent mechanisms regulating ischemia/reperfusion injury in primary neurons

2021 ◽  
Vol 12 (5) ◽  
Author(s):  
Anthony R. Anzell ◽  
Garrett M. Fogo ◽  
Zoya Gurm ◽  
Sarita Raghunayakula ◽  
Joseph M. Wider ◽  
...  
Keyword(s):  
Cortical Neurons ◽  
Ischemia Reperfusion Injury ◽  
Mitochondrial Dynamics ◽  
Ischemia Reperfusion ◽  
Mitochondrial Fission ◽  
Conditional Knockout ◽  
Mitochondrial Morphology ◽  
Primary Neurons ◽  
Mitochondrial Fragmentation

AbstractMitochondrial dynamics and mitophagy are constitutive and complex systems that ensure a healthy mitochondrial network through the segregation and subsequent degradation of damaged mitochondria. Disruption of these systems can lead to mitochondrial dysfunction and has been established as a central mechanism of ischemia/reperfusion (I/R) injury. Emerging evidence suggests that mitochondrial dynamics and mitophagy are integrated systems; however, the role of this relationship in the context of I/R injury remains unclear. To investigate this concept, we utilized primary cortical neurons isolated from the novel dual-reporter mitochondrial quality control knockin mice (C57BL/6-Gt(ROSA)26Sortm1(CAG-mCherry/GFP)Ganl/J) with conditional knockout (KO) of Drp1 to investigate changes in mitochondrial dynamics and mitophagic flux during in vitro I/R injury. Mitochondrial dynamics was quantitatively measured in an unbiased manner using a machine learning mitochondrial morphology classification system, which consisted of four different classifications: network, unbranched, swollen, and punctate. Evaluation of mitochondrial morphology and mitophagic flux in primary neurons exposed to oxygen-glucose deprivation (OGD) and reoxygenation (OGD/R) revealed extensive mitochondrial fragmentation and swelling, together with a significant upregulation in mitophagic flux. Furthermore, the primary morphology of mitochondria undergoing mitophagy was classified as punctate. Colocalization using immunofluorescence as well as western blot analysis revealed that the PINK1/Parkin pathway of mitophagy was activated following OGD/R. Conditional KO of Drp1 prevented mitochondrial fragmentation and swelling following OGD/R but did not alter mitophagic flux. These data provide novel evidence that Drp1 plays a causal role in the progression of I/R injury, but mitophagy does not require Drp1-mediated mitochondrial fission.

scholarly journals Mitochondrial Dynamics Regulation in Skin Fibroblasts from Mitochondrial Disease Patients

Biomolecules ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 450 ◽  
Author(s):  
Takeshi Tokuyama ◽  
Asei Hirai ◽  
Isshin Shiiba ◽  
Naoki Ito ◽  
Keigo Matsuno ◽  
...  
Keyword(s):  
Mitochondrial Disease ◽  
Mitochondrial Myopathy ◽  
Mitochondrial Dynamics ◽  
Mitochondrial Fission ◽  
Critical Role ◽  
Leigh Syndrome ◽  
Mitochondrial Morphology ◽  
Mitochondrial Fragmentation ◽  
Cellular Toxicity ◽  
Morphologic Changes

Mitochondria are highly dynamic organelles that constantly fuse, divide, and move, and their function is regulated and maintained by their morphologic changes. Mitochondrial disease (MD) comprises a group of disorders involving mitochondrial dysfunction. However, it is not clear whether changes in mitochondrial morphology are related to MD. In this study, we examined mitochondrial morphology in fibroblasts from patients with MD (mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) and Leigh syndrome). We observed that MD fibroblasts exhibited significant mitochondrial fragmentation by upregulation of Drp1, which is responsible for mitochondrial fission. Interestingly, the inhibition of mitochondrial fragmentation by Drp1 knockdown enhanced cellular toxicity and led to cell death in MD fibroblasts. These results suggest that mitochondrial fission plays a critical role in the attenuation of mitochondrial damage in MD fibroblasts.

scholarly journals Mitochondrial fusion regulates proliferation and differentiation in the type II neuroblast lineage in Drosophila

2021 ◽  
Author(s):  
Dnyanesh Dubal ◽  
Prachiti Moghe ◽  
Bhavin Uttekar ◽  
Richa Rikhy
Keyword(s):  
Notch Signaling ◽  
Mitochondrial Dynamics ◽  
Stem Cell Differentiation ◽  
Mitochondrial Fusion ◽  
Mitochondrial Outer Membrane ◽  
Mitochondrial Activity ◽  
Mitochondrial Morphology ◽  
Type Ii ◽  
Mitochondrial Fragmentation ◽  
Proliferation And Differentiation

Optimal mitochondrial function determined by mitochondrial dynamics, morphology and activity is coupled to stem cell differentiation and organism development. However, the mechanisms of interaction of signaling pathways with mitochondrial morphology and activity are not completely understood. We assessed the role of mitochondrial fusion and fission in differentiation of neural stem cells called neuroblasts (NB) in the Drosophila brain. Depletion of mitochondrial inner membrane fusion protein Opa1 and mitochondrial outer membrane protein Marf in the Drosophila type II neuroblast lineage led to mitochondrial fragmentation and loss of activity. Opa1 and Marf depletion did not affect the numbers and polarity of type II neuroblasts but led to a decrease in proliferation and differentiation of cells in the lineage. On the contrary, loss of mitochondrial fission protein Drp1 led to mitochondrial fusion but did not show defects in proliferation and differentiation. Depletion of Drp1 along with Opa1 or Marf also led to mitochondrial fusion and suppressed fragmentation, loss of mitochondrial activity, proliferation and differentiation in the type II NB lineage. We found that Notch signaling depletion via the canonical pathway showed mitochondrial fragmentation and loss of differentiation similar to Opa1 mutants. An increase in Notch signaling required mitochondrial fusion for NB proliferation. Further, Drp1 mutants in combination with Notch depletion showed mitochondrial fusion and drove differentiation in the lineage suggesting that fused mitochondria can influence Notch signaling driven differentiation in the type II NB lineage. Our results implicate a crosstalk between Notch signalling, mitochondrial activity and mitochondrial fusion as an essential step in type II NB differentiation.

scholarly journals Dynamin-related protein 1 mediates low glucose-induced endothelial dysfunction in human arterioles

2017 ◽  
Vol 312 (3) ◽  
pp. H515-H527 ◽  
Author(s):  
Michael J. Tanner ◽  
Jingli Wang ◽  
Rong Ying ◽  
Tisha B. Suboc ◽  
Mobin Malik ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Endothelial Dysfunction ◽  
Endothelial Function ◽  
Mitochondrial Dynamics ◽  
Mitochondrial Fission ◽  
Cardiovascular Complications ◽  
Mitochondrial Morphology ◽  
Vascular Relaxation ◽  
Mitochondrial Fragmentation ◽  
Low Glucose

Intensive glycemic regulation has resulted in an increased incidence of hypoglycemia. Hypoglycemic burden correlates with adverse cardiovascular complications and contributes acutely and chronically to endothelial dysfunction. Prior data indicate that mitochondrial dysfunction contributes to hypoglycemia-induced endothelial dysfunction, but the mechanisms behind this linkage remain unknown. We attempt to determine whether clinically relevant low-glucose (LG) exposures acutely induce endothelial dysfunction through activation of the mitochondrial fission process. Characterization of mitochondrial morphology was carried out in cultured endothelial cells by using confocal microscopy. Isolated human arterioles were used to explore the effect LG-induced mitochondrial fission has on the formation of detrimental reactive oxygen species (ROS), bioavailability of nitric oxide (NO), and endothelial-dependent vascular relaxation. Fluorescence microscopy was employed to visualize changes in mitochondrial ROS and NO levels and videomicroscopy applied to measure vasodilation response. Pharmacological disruption of the profission protein Drp1 with Mdivi-1 during LG exposure reduced mitochondrial fragmentation among vascular endothelial cells (LG: 0.469; LG+Mdivi-1: 0.276; P = 0.003), prevented formation of vascular ROS (LG: 2.036; LG+Mdivi-1: 1.774; P = 0.005), increased the presence of NO (LG: 1.352; LG+Mdivi-1: 1.502; P = 0.048), and improved vascular dilation response to acetylcholine (LG: 31.6%; LG+Mdivi-1; 78.5% at maximum dose; P < 0.001). Additionally, decreased expression of Drp1 via siRNA knockdown during LG conditions also improved vascular relaxation. Exposure to LG imparts endothelial dysfunction coupled with altered mitochondrial phenotypes among isolated human arterioles. Disruption of Drp1 and subsequent mitochondrial fragmentation events prevents impaired vascular dilation, restores mitochondrial phenotype, and implicates mitochondrial fission as a primary mediator of LG-induced endothelial dysfunction. NEW & NOTEWORTHY Acute low-glucose exposure induces mitochondrial fragmentation in endothelial cells via Drp1 and is associated with impaired endothelial function in human arterioles. Targeting of Drp1 prevents fragmentation, improves vasofunction, and may provide a therapeutic target for improving cardiovascular complications among diabetics. Listen to this article’s corresponding podcast @ http://ajpheart.podbean.com/e/mitochondrial-dynamics-impact-endothelial-function/ .

scholarly journals Mitochondrial Dynamics Associated with Oxygen-Glucose Deprivation in Rat Primary Neuronal Cultures

PLoS ONE ◽  
2013 ◽  
Vol 8 (5) ◽  
pp. e63206 ◽  
Author(s):  
Edina A. Wappler ◽  
Adam Institoris ◽  
Somhrita Dutta ◽  
Prasad V. G. Katakam ◽  
David W. Busija
Keyword(s):  
Mitochondrial Dynamics ◽  
Glucose Deprivation ◽  
Oxygen Glucose Deprivation ◽  
Neuronal Cultures ◽  
Primary Neuronal Cultures

scholarly journals Squamosamide Derivative FLZ Diminishes Aberrant Mitochondrial Fission by Inhibiting Dynamin-Related Protein 1

2021 ◽  
Vol 12 ◽  
Author(s):  
Hanyu Yang ◽  
Lu Wang ◽  
Caixia Zang ◽  
Xu Yang ◽  
Xiuqi Bao ◽  
...  
Keyword(s):  
Mitochondrial Dysfunction ◽  
Dopaminergic Neurons ◽  
Motor Coordination ◽  
Mitochondrial Dynamics ◽  
Mitochondrial Fission ◽  
Mitochondrial Morphology ◽  
Protective Effects ◽  
Related Protein ◽  
Mitochondrial Fragmentation

Mitochondrial dysfunction is involved in the pathogenesis of Parkinson’s disease (PD). Mitochondrial morphology is dynamic and precisely regulated by mitochondrial fission and fusion machinery. Aberrant mitochondrial fragmentation, which can result in cell death, is controlled by the mitochondrial fission protein, dynamin-related protein 1 (Drp1). Our previous results demonstrated that FLZ could correct mitochondrial dysfunction, but the effect of FLZ on mitochondrial dynamics remain uncharacterized. In this study, we investigated the effect of FLZ and the role of Drp1 on 1-methyl-4-phenylpyridinium (MPP+)–induced mitochondrial fission in neurons. We observed that FLZ blocked Drp1, inhibited Drp1 enzyme activity, and reduced excessive mitochondrial fission in cultured neurons. Furthermore, by inhibiting mitochondrial fission and ROS production, FLZ improved mitochondrial integrity and membrane potential, resulting in neuroprotection. FLZ curtailed the reduction of synaptic branches of primary cultured dopaminergic neurons caused by MPP+ exposure, reduced abnormal fission, restored normal mitochondrial distribution in neurons, and exhibited protective effects on dopaminergic neurons. The in vitro research results were validated using an MPTP-induced PD mouse model. The in vivo results revealed that FLZ significantly reduced the mitochondrial translocation of Drp1 in the midbrain of PD mice, which, in turn, reduced the mitochondrial fragmentation in mouse substantia nigra neurons. FLZ also protected dopaminergic neurons in PD mice and increased the dopamine content in the striatum, which improved the motor coordination ability of the mice. These findings elucidate this newly discovered mechanism through which FLZ produces neuroprotection in PD.

Perturbations in mitochondrial dynamics by p66Shc lead to renal tubular oxidative injury in human diabetic nephropathy

2018 ◽  
Vol 132 (12) ◽  
pp. 1297-1314 ◽  
Author(s):  
Ming Zhan ◽  
Irtaza Usman ◽  
Jingbo Yu ◽  
Liemin Ruan ◽  
Xueyan Bian ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Diabetic Nephropathy ◽  
Cell Injury ◽  
Mitochondrial Dynamics ◽  
Oxidative Injury ◽  
Tubular Cell ◽  
Mitochondrial Morphology ◽  
Mitochondrial Fragmentation ◽  
Mitochondrial Dynamic ◽  
Renal Tubular

Renal tubular injury is increasingly being recognized as an early characteristic of diabetic nephropathy (DN). Mitochondrial dynamic alterations and redox protein p66Shc-mediated oxidative stress are both critical for ensuing diabetic tubular cell injury and apoptosis; whether these two processes are interlinked remains unclear. In the present study, we observed changes in mitochondrial morphology and expression of associated proteins in tubules of patients with DN. We demonstrated mitochondrial fragmentation as an important pathogenic feature of tubular cell injury that is linked to oxidative stress and p66Shc up-regulation. In renal proximal tubular cells, alterations in mitochondrial dynamics and expression of fission–fusion proteins were observed under high glucose (HG) ambience, along with p66Shc Ser36 phosphorylation. Gene ablation of p66Shc alleviated HG-induced mitochondrial fragmentation, down-regulated Fis1 and reduced p66Shc–Fis1 binding, increased Mfn1 expression, and disrupted interactions between Mfn1 and proapoptotic Bak. Overexpression of p66Shc exacerbated these changes, whereas overexpression of dominant-negative p66Shc Ser36 mutant had a marginal effect under HG, indicating that p66Shc phosphorylation as a prerequisite in the modulation of mitochondrial dynamics. Disrupted mitochondrial dynamics and enhanced Mfn1–Bak interactions modulated by p66Shc led to loss of mitochondrial voltage potential, cytochrome C release, excessive ROS generation, and apoptosis. Taken together, these results link p66Shc to mitochondrial dynamic alterations in the pathogenesis of DN and unveil a novel mechanism by which p66Shc mediates HG-induced mitochondrial fragmentation and proapoptotic signaling that results in oxidative injury and apoptosis in the tubular compartment in human diabetic nephropathy.

scholarly journals Mitochondrial Structural Changes in the Pathogenesis of Diabetic Retinopathy

2019 ◽  
Vol 8 (9) ◽  
pp. 1363 ◽  
Author(s):  
Roy ◽  
Kim ◽  
Sankaramoorthy
Keyword(s):  
Diabetic Retinopathy ◽  
High Glucose ◽  
Structural Changes ◽  
Mitochondrial Dynamics ◽  
Mitochondrial Morphology ◽  
Mitochondrial Fragmentation ◽  
Diabetic Retina ◽  
High Glucose Condition ◽  
Physical Changes ◽  
Work Supports

Abstract: At the core of proper mitochondrial functionality is the maintenance of its structure and morphology. Physical changes in mitochondrial structure alter metabolic pathways inside mitochondria, affect mitochondrial turnover, disturb mitochondrial dynamics, and promote mitochondrial fragmentation, ultimately triggering apoptosis. In high glucose condition, increased mitochondrial fragmentation contributes to apoptotic death in retinal vascular and Müller cells. Although alterations in mitochondrial morphology have been detected in several diabetic tissues, it remains to be established in the vascular cells of the diabetic retina. From a mechanistic standpoint, our current work supports the notion that increased expression of fission genes and decreased expression of fusion genes are involved in promoting excessive mitochondrial fragmentation. While mechanistic insights are only beginning to reveal how high glucose alters mitochondrial morphology, the consequences are clearly seen as release of cytochrome c from fragmented mitochondria triggers apoptosis. Current findings raise the prospect of targeting excessive mitochondrial fragmentation as a potential therapeutic strategy for treatment of diabetic retinopathy. While biochemical and epigenetic changes have been reported to be associated with mitochondrial dysfunction, this review focuses on alterations in mitochondrial morphology, and their impact on mitochondrial function and pathogenesis of diabetic retinopathy.

scholarly journals Overexpression of ryanodine receptor type 1 enhances mitochondrial fragmentation and Ca2+-induced ATP production in cardiac H9c2 myoblasts

2013 ◽  
Vol 305 (12) ◽  
pp. H1736-H1751 ◽  
Author(s):  
Jin O-Uchi ◽  
Bong Sook Jhun ◽  
Stephen Hurst ◽  
Sara Bisetto ◽  
Polina Gross ◽  
...  
Keyword(s):  
Ryanodine Receptor ◽  
Mitochondrial Dynamics ◽  
Cell Types ◽  
Cardiac Cells ◽  
Mitochondrial Morphology ◽  
Mitochondrial Fragmentation ◽  
Cardiac Sarcoplasmic Reticulum ◽  
Atp Production ◽  
H9c2 Myoblasts

Ca+ influx to mitochondria is an important trigger for both mitochondrial dynamics and ATP generation in various cell types, including cardiac cells. Mitochondrial Ca2+ influx is mainly mediated by the mitochondrial Ca2+ uniporter (MCU). Growing evidence also indicates that mitochondrial Ca2+ influx mechanisms are regulated not solely by MCU but also by multiple channels/transporters. We have previously reported that skeletal muscle-type ryanodine receptor (RyR) type 1 (RyR1), which expressed at the mitochondrial inner membrane, serves as an additional Ca2+ uptake pathway in cardiomyocytes. However, it is still unclear which mitochondrial Ca2+ influx mechanism is the dominant regulator of mitochondrial morphology/dynamics and energetics in cardiomyocytes. To investigate the role of mitochondrial RyR1 in the regulation of mitochondrial morphology/function in cardiac cells, RyR1 was transiently or stably overexpressed in cardiac H9c2 myoblasts. We found that overexpressed RyR1 was partially localized in mitochondria as observed using both immunoblots of mitochondrial fractionation and confocal microscopy, whereas RyR2, the main RyR isoform in the cardiac sarcoplasmic reticulum, did not show any expression at mitochondria. Interestingly, overexpression of RyR1 but not MCU or RyR2 resulted in mitochondrial fragmentation. These fragmented mitochondria showed bigger and sustained mitochondrial Ca2+ transients compared with basal tubular mitochondria. In addition, RyR1-overexpressing cells had a higher mitochondrial ATP concentration under basal conditions and showed more ATP production in response to cytosolic Ca2+ elevation compared with nontransfected cells as observed by a matrix-targeted ATP biosensor. These results indicate that RyR1 possesses a mitochondrial targeting/retention signal and modulates mitochondrial morphology and Ca2+-induced ATP production in cardiac H9c2 myoblasts.

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