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.

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 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 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 Dynamics in Stem Cells and Differentiation

2018 ◽  
Vol 19 (12) ◽  
pp. 3893 ◽  
Author(s):  
Bong Seo ◽  
Sang Yoon ◽  
Jeong Do
Keyword(s):  
Cell Cycle ◽  
Stem Cells ◽  
Embryonic Development ◽  
Cellular Differentiation ◽  
Mitochondrial Dynamics ◽  
Cellular Reprogramming ◽  
Mitochondrial Morphology ◽  
Main Function ◽  
Tissue Formation ◽  
Atp Production

Mitochondria are highly dynamic organelles that continuously change their shape. Their main function is adenosine triphosphate (ATP) production; however, they are additionally involved in a variety of cellular phenomena, such as apoptosis, cell cycle, proliferation, differentiation, reprogramming, and aging. The change in mitochondrial morphology is closely related to the functionality of mitochondria. Normal mitochondrial dynamics are critical for cellular function, embryonic development, and tissue formation. Thus, defects in proteins involved in mitochondrial dynamics that control mitochondrial fusion and fission can affect cellular differentiation, proliferation, cellular reprogramming, and aging. Here, we review the processes and proteins involved in mitochondrial dynamics and their various associated cellular phenomena.

scholarly journals Porphyromonas gingivalis infection promotes mitochondrial dysfunction through Drp1-dependent mitochondrial fission in endothelial cells

2021 ◽  
Vol 13 (1) ◽  
Author(s):  
Tong Xu ◽  
Qin Dong ◽  
Yuxiao Luo ◽  
Yanqing Liu ◽  
Liang Gao ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Mitochondrial Dysfunction ◽  
Porphyromonas Gingivalis ◽  
Vascular Endothelial Cells ◽  
Mitochondrial Fission ◽  
Mitochondrial Morphology ◽  
Mitochondrial Fragmentation ◽  
Atp Production ◽  
Luminescence Assay ◽  
The Impact

AbstractPorphyromonas gingivalis (P. gingivalis), a key pathogen in periodontitis, has been shown to accelerate the progression of atherosclerosis (AS). However, the definite mechanisms remain elusive. Emerging evidence supports an association between mitochondrial dysfunction and AS. In our study, the impact of P. gingivalis on mitochondrial dysfunction and the potential mechanism were investigated. The mitochondrial morphology of EA.hy926 cells infected with P. gingivalis was assessed by transmission electron microscopy, mitochondrial staining, and quantitative analysis of the mitochondrial network. Fluorescence staining and flow cytometry analysis were performed to determine mitochondrial reactive oxygen species (mtROS) and mitochondrial membrane potential (MMP) levels. Cellular ATP production was examined by a luminescence assay kit. The expression of key fusion and fission proteins was evaluated by western blot and immunofluorescence. Mdivi-1, a specific Drp1 inhibitor, was used to elucidate the role of Drp1 in mitochondrial dysfunction. Our findings showed that P. gingivalis infection induced mitochondrial fragmentation, increased the mtROS levels, and decreased the MMP and ATP concentration in vascular endothelial cells. We observed upregulation of Drp1 (Ser616) phosphorylation and translocation of Drp1 to mitochondria. Mdivi-1 blocked the mitochondrial fragmentation and dysfunction induced by P. gingivalis. Collectively, these results revealed that P. gingivalis infection promoted mitochondrial fragmentation and dysfunction, which was dependent on Drp1. Mitochondrial dysfunction may represent the mechanism by which P. gingivalis exacerbates atherosclerotic lesions.

scholarly journals RCAN1.4 mediates high glucose-induced matrix production by stimulating mitochondrial fission in mesangial cells

2020 ◽  
Vol 40 (1) ◽  
Author(s):  
Hong-Min Chen ◽  
Jia-Jia Dai ◽  
Rui Zhu ◽  
Xue-Yu Sang ◽  
Fang-Fang Peng ◽  
...  
Keyword(s):  
High Glucose ◽  
Matrix Protein ◽  
Mesangial Cells ◽  
Mitochondrial Dynamics ◽  
Mitochondrial Fission ◽  
Cell Types ◽  
Glomerular Mesangial Cells ◽  
Mitochondrial Fragmentation ◽  
Mitochondrial Dynamic ◽  
Matrix Production

Abstract High glucose (HG)-induced mitochondrial dynamic changes and oxidative damage are closely related to the development and progression of diabetic kidney disease (DKD). Recent studies suggest that regulators of calcineurin 1 (RCAN1) is involved in the regulation of mitochondrial function in different cell types, so we investigate the role of RCAN1 in mitochondrial dynamics under HG ambience in rat glomerular mesangial cells (MCs). MCs subjected to HG exhibited an isoform-specific up-regulation of RCAN1.4 at both mRNA and protein levels. RCAN1.4 overexpression induced translocation of Dynamin related protein 1 (Drp1) to mitochondria, mitochondrial fragmentation and depolarization, accompanied by increased matrix production under normal glucose and HG ambience. In contrast, decreasing the expression of RCAN1.4 by siRNA inhibited HG-induced mitochondrial fragmentation and matrix protein up-regulation. Moreover, both mitochondrial fission inhibitor Mdivi-1 and Drp1 shRNA prevented RCAN1.4-induced fibronectin up-regulation, suggesting that RCAN1.4-induced matrix production is dependent on its modulation of mitochondrial fission. Although HG-induced RCAN1.4 up-regulation was achieved by activating calcineurin, RCAN1.4-mediated mitochondrial fragmentation and matrix production is independent of calcineurin activity. These results provide the first evidence for the HG-induced RCAN1.4 up-regulation involving increased mitochondrial fragmentation, leading to matrix protein up-regulation.

scholarly journals Mitochondrial dysfunction underlying sporadic inclusion body myositis is ameliorated by the mitochondrial homing drug MA-5

PLoS ONE ◽  
2020 ◽  
Vol 15 (12) ◽  
pp. e0231064
Author(s):  
Yoshitsugu Oikawa ◽  
Rumiko Izumi ◽  
Masashi Koide ◽  
Yoshihiro Hagiwara ◽  
Makoto Kanzaki ◽  
...  
Keyword(s):  
Mitochondrial Dysfunction ◽  
Inclusion Body ◽  
Inclusion Body Myositis ◽  
Mitochondrial Dynamics ◽  
Inflammatory Myopathy ◽  
Idiopathic Inflammatory Myopathy ◽  
Mitochondrial Morphology ◽  
Atp Production ◽  
Bioenergetic Analysis ◽  
Sporadic Inclusion Body Myositis

Sporadic inclusion body myositis (sIBM) is the most common idiopathic inflammatory myopathy, and several reports have suggested that mitochondrial abnormalities are involved in its etiology. We recruited 9 sIBM patients and found significant histological changes and an elevation of growth differential factor 15 (GDF15), a marker of mitochondrial disease, strongly suggesting the involvement of mitochondrial dysfunction. Bioenergetic analysis of sIBM patient myoblasts revealed impaired mitochondrial function. Decreased ATP production, reduced mitochondrial size and reduced mitochondrial dynamics were also observed in sIBM myoblasts. Cell vulnerability to oxidative stress also suggested the existence of mitochondrial dysfunction. Mitochonic acid-5 (MA-5) increased the cellular ATP level, reduced mitochondrial ROS, and provided protection against sIBM myoblast death. MA-5 also improved the survival of sIBM skin fibroblasts as well as mitochondrial morphology and dynamics in these cells. The reduction in the gene expression levels of Opa1 and Drp1 was also reversed by MA-5, suggesting the modification of the fusion/fission process. These data suggest that MA-5 may provide an alternative therapeutic strategy for treating not only mitochondrial diseases but also sIBM.

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 Mitochondrial Dynamics in Adult Cardiomyocytes and Heart Diseases

2020 ◽  
Vol 8 ◽  
Author(s):  
Anqi Li ◽  
Meng Gao ◽  
Wenting Jiang ◽  
Yuan Qin ◽  
Guohua Gong
Keyword(s):  
Mitochondrial Dynamics ◽  
Heart Diseases ◽  
Cell Types ◽  
Oxidative Stress Response ◽  
Mitochondrial Morphology ◽  
Cellular Functions ◽  
Mature Adult ◽  
Adult Cardiomyocytes ◽  
Atp Generation ◽  
The Relationship

Mitochondria are the powerhouse organelles of cells; they participate in ATP generation, calcium homeostasis, oxidative stress response, and apoptosis. Thus, maintenance of mitochondrial function is critical for cellular functions. As highly dynamic organelles, the function of mitochondria is dynamically regulated by their fusion and fission in many cell types, which regulate mitochondrial morphology, number, distribution, metabolism, and biogenesis in cells. Mature rod-shaped cardiomyocytes contain thousands of end-to-end contacted spheroid mitochondria. The movement of mitochondria in these cells is limited, which hinders the impetus for research into mitochondrial dynamics in adult cardiomyocytes. In this review, we discuss the most recent progress in mitochondrial dynamics in mature (adult) cardiomyocytes and the relationship thereof with heart diseases.

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/ .

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