Acid Sphingomyelinase Downregulation Enhances Mitochondrial Fusion and Promotes Oxidative Metabolism in a Mouse Model of Melanoma

Melanoma is the most severe type of skin cancer. Its unique and heterogeneous metabolism, relying on both glycolysis and oxidative phosphorylation, allows it to adapt to disparate conditions. Mitochondrial function is strictly interconnected with mitochondrial dynamics and both are fundamental in tumour progression and metastasis. The malignant phenotype of melanoma is also regulated by the expression levels of the enzyme acid sphingomyelinase (A-SMase). By modulating at transcriptional level A-SMase in the melanoma cell line B16-F1 cells, we assessed the effect of enzyme downregulation on mitochondrial dynamics and function. Our results demonstrate that A-SMase influences mitochondrial morphology by affecting the expression of mitofusin 1 and OPA1. The enhanced expression of the two mitochondrial fusion proteins, observed when A-SMase is expressed at low levels, correlates with the increase of mitochondrial function via the stimulation of the genes PGC-1alpha and TFAM, two genes that preside over mitochondrial biogenesis. Thus, the reduction of A-SMase expression, observed in malignant melanomas, may determine their metastatic behaviour through the stimulation of mitochondrial fusion, activity and biogenesis, conferring a metabolic advantage to melanoma cells.

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

International Journal of Molecular Sciences ◽

10.3390/ijms22094617 ◽

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.

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A comprehensive approach for artifact-free sample preparation and assessment of mitochondrial morphology in tissue and cultured cells

10.1101/2021.06.27.450055 ◽

2021 ◽

Author(s):

Antentor Hinton ◽

Prasanna Katti ◽

Trace A. Christensen ◽

Margaret Mungai ◽

Jianqiang Shao ◽

...

Keyword(s):

Structural Changes ◽

Cultured Cells ◽

Mitochondrial Dynamics ◽

Mitochondrial Morphology ◽

Specimen Preparation ◽

Preparation Methods ◽

Cellular Environment ◽

Stress Changes ◽

Precise Relationship ◽

And Function

Mitochondrial dynamics and morphology (fission, fusion, and the formation of nanotunnels) are very sensitive to the cellular environment and may be adversely affected by oxidative stress, changes in calcium levels, and hypoxia. Investigating the precise relationship between the organelle structure and function requires methods that can adequately preserve the structure while providing accurate, quantitative measurements of mitochondrial morphological attributes. Here, we demonstrate a practical approach for preserving and measuring fine structural changes in two-dimensional electron micrographs, obtained using transmission electron microscopy, highlighting the specific advantages of this technique. Additionally, this study defines a set of quantifiable metrics that can be applied to measure mitochondrial architecture and other organellar structures. Finally, we validated specimen preparation methods that avoid the introduction of morphological artifacts in mitochondrial appearance that do not require whole-animal perfusion.

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

Stem Cells International ◽

10.1155/2019/6380135 ◽

2019 ◽

Vol 2019 ◽

pp. 1-12 ◽

Cited By ~ 4

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.

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Bu-Yin-Qian-Zheng Formula Ameliorates MPP+-Induced Mitochondrial Dysfunction in Parkinson’s Disease via Parkin

Frontiers in Pharmacology ◽

10.3389/fphar.2020.577017 ◽

2020 ◽

Vol 11 ◽

Author(s):

Hao-Jie Ma ◽

Cong Gai ◽

Yuan Chai ◽

Wan-Di Feng ◽

Cui-Cui Cheng ◽

...

Keyword(s):

Protein Expression ◽

Mitochondrial Dysfunction ◽

Cell Survival ◽

Mitochondrial Function ◽

Survival Rates ◽

Transient Transfection ◽

Mitochondrial Fusion ◽

Mitochondrial Morphology ◽

Protein Levels ◽

Atp Levels

As a typical traditional Chinese medicine, Bu-Yin-Qian-Zheng Formula (BYQZF) has been shown to have neuroprotective effects in patients with Parkinson’s disease (PD), particularly by ameliorating mitochondrial dysfunction and regulating expression of the parkin protein. However, the underlying mechanisms by which BYQZF affects mitochondrial function through parkin are unclear. Accordingly, in this study, we evaluated the mechanisms by which BYQZF ameliorates mitochondrial dysfunction through parkin in PD. We constructed a parkin-knockdown cell model and performed fluorescence microscopy to observe transfected SH-SY5Y cells. Quantitative real-time reverse transcription polymerase chain reaction and western blotting were conducted to detect the mRNA and protein expression levels of parkin. Additionally, we evaluated the cell survival rates, ATP levels, mitochondrial membrane potential (ΔΨm), mitochondrial morphology, parkin protein expression, PINK1 protein expression, and mitochondrial fusion and fission protein expression after treatment with MPP+ and BYQZF. Our results showed that cell survival rates, ATP levels, ΔΨm, mitochondrial morphology, parkin protein levels, PINK1 protein levels, and mitochondrial fusion protein levels were reduced after MPP+ treatment. In contrast, mitochondrial fission protein levels were increased after MPP+ treatment. Moreover, after transient transfection with a negative control plasmid, the above indices were significantly increased by BYQZF. However, there were no obvious differences in these indices after transient transfection with a parkin-knockdown plasmid. Our findings suggest that BYQZF has protective effects on mitochondrial function in MPP+-induced SH-SY5Y cells via parkin-dependent regulation of mitochondrial dynamics.

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P5994Role of BGP-15 treatment in hypertensive heart failure progression and mitochondrial protection

European Heart Journal ◽

10.1093/eurheartj/ehz746.0715 ◽

2019 ◽

Vol 40 (Supplement_1) ◽

Author(s):

O Horvath ◽

L Deres ◽

K Ordog ◽

K Bruszt ◽

B Sumegi ◽

...

Keyword(s):

Heart Failure ◽

Mitochondrial Function ◽

Cardiac Remodeling ◽

In Vitro Model ◽

Mitochondrial Dynamics ◽

Treated Group ◽

Mitochondrial Structure ◽

Vitro Model ◽

And Function

Abstract Introduction The deterioration of mitochondrial quality control greatly contributes to the hypertension induced cardiac remodeling and progression of heart failure. Our previous in vitro results demonstrated the mitochondrial protective effect of antioxidant BGP-15 compound in the presence of cellular stress. Purpose In our recent study we investigated the effect of BGP-15 on cardiac remodeling in spontaneously hypertensive rats (SHR) with manifested heart failure and on mitochondrial dynamics and function in cell culture model. Methods 15-month-old male SHR received 25 mg/kg/day BGP-15 (SHR-B) or placebo (SHR-C) for 18 weeks. Age matched Wistar rats (WKY) were used as normotensive control. The heart function was monitored by echocardiography. Histological preparations were made from cardiac tissue. Neonatal rat cardiomyocytes (NRCMs) were used as in vitro model. 150 μM H2O2 stress and 50 μM BGP-15 treatment was applied. Mitochondrial network was stained with MitoTracker Red. Mitochondrial membrane potential was detected using JC-1 dye, while mitochondrial function was monitored by the Agilent Seahorse XFp, Cell Mito Stress Test. In both model the cellular levels of mitochondrial dynamics proteins were measured in Western blot. To study the ultrastructure we used electron microscopy in our in vivo and in vitro model. Results Left ventricular (LV) mass and LV wall thickness were increased significantly in SHR-C group compared to the initial values (p<0.05). These parameters were decreased considerably in the SHR-B group. Ejection fraction (EF%) decreased in both SHR group although this downturn was minimal because of the treatment. Chronic high blood pressure caused higher collagen deposition in SHR-C rats that was significantly diminished in the SHR-B group. Regarding the mitochondrial function decrease in the levels of fusion proteins OPA1 and MFN2 was observed in the SHR-C group. These differences were significantly reduced by BGP-15 treatment (p<0.05). Mitigation of the level of fission protein DRP1 was however reduced by BGP-15 (p<0.05). In our cellular model, we observed that the H2O2-induced mitochondrial fragmentation was decreased by BGP-15 treatment (p<0.05). BGP-15 treatment prevented mitochondrial membrane potential fall in H2O2 stress (p<0.05). There was no significant difference in basal respiration among groups by monitoring the mitochondrial function. The maximal respiration capacity and ATP production were significantly higher in the BGP-15 treated group in comparison to the stressed group (p<0.05). Conclusion BGP-15 treatment has beneficial effects on mitochondrial dynamics and structure by promoting fusion processes. It also supports the maintenance of mitochondrial function through the preservation of the mitochondrial structure. The mitigation of remodeling processes and the preserved EF in the treated group are results at least partly of the comprehensible effects of BGP-15 on mitochondrial structure and function. Acknowledgement/Funding GINOP-2.3.2-15-2016-00049; GINOP-2.3.2-15-2016-00048; GINOP-2.3.3-15-2016-00025

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

The Journal of Cell Biology ◽

10.1083/jcb.200309082 ◽

2004 ◽

Vol 164 (4) ◽

pp. 493-499 ◽

Cited By ~ 303

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.

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Mitochondrial Dysfunction and Oxidative Stress in Alzheimer’s Disease

Frontiers in Aging Neuroscience ◽

10.3389/fnagi.2021.617588 ◽

2021 ◽

Vol 13 ◽

Cited By ~ 1

Author(s):

Afzal Misrani ◽

Sidra Tabassum ◽

Li Yang

Keyword(s):

Oxidative Stress ◽

Alzheimer’S Disease ◽

Alzheimer's Disease ◽

Mitochondrial Dysfunction ◽

Mitochondrial Function ◽

Mitochondrial Dynamics ◽

Mitochondrial Morphology ◽

Therapeutic Approaches ◽

The Impact ◽

And Oxidative Stress

Mitochondria play a pivotal role in bioenergetics and respiratory functions, which are essential for the numerous biochemical processes underpinning cell viability. Mitochondrial morphology changes rapidly in response to external insults and changes in metabolic status via fission and fusion processes (so-called mitochondrial dynamics) that maintain mitochondrial quality and homeostasis. Damaged mitochondria are removed by a process known as mitophagy, which involves their degradation by a specific autophagosomal pathway. Over the last few years, remarkable efforts have been made to investigate the impact on the pathogenesis of Alzheimer’s disease (AD) of various forms of mitochondrial dysfunction, such as excessive reactive oxygen species (ROS) production, mitochondrial Ca2+ dyshomeostasis, loss of ATP, and defects in mitochondrial dynamics and transport, and mitophagy. Recent research suggests that restoration of mitochondrial function by physical exercise, an antioxidant diet, or therapeutic approaches can delay the onset and slow the progression of AD. In this review, we focus on recent progress that highlights the crucial role of alterations in mitochondrial function and oxidative stress in the pathogenesis of AD, emphasizing a framework of existing and potential therapeutic approaches.

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

10.1101/2021.01.08.425832 ◽

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.

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OGT regulates mitochondrial biogenesis and function via diabetes susceptibility gene Pdx1

10.2337/figshare.15831735.v1 ◽

2021 ◽

Author(s):

Ramkumar Mohan ◽

Seokwon Jo ◽

Amber Lockridge ◽

Deborah A. Ferrington ◽

Kevin Murray ◽

...

Keyword(s):

Mitochondrial Function ◽

Susceptibility Gene ◽

Mitochondrial Morphology ◽

Cell Physiology ◽

Β Cells ◽

Β Cell ◽

Atp Production ◽

Glcnac Transferase ◽

And Function

O-GlcNAc transferase (OGT), a nutrient-sensor sensitive to glucose flux, is highly expressed in the pancreas. However, the role of OGT in the mitochondria of β-cells is unexplored. Here, we identified the role of OGT in mitochondrial function in β-cells. Constitutive deletion of OGT (βOGTKO) or inducible ablation in mature β-cells (iβOGTKO) causes distinct effects on mitochondrial morphology and function. Islets from βOGTKO, but not iβOGTKO, mice display swollen mitochondria, reduced glucose-stimulated oxygen consumption rate, ATP production and glycolysis. Alleviating ER stress by genetic deletion of Chop did not rescue the mitochondrial dysfunction in βOGTKO mice. We identified altered islet proteome between βOGTKO and iβOGTKO mice. Pancreatic and duodenal homeobox 1 (Pdx1) was reduced in in βOGTKO islets. Pdx1 over-expression increased insulin content and improved mitochondrial morphology and function in βOGTKO islets. These data underscore the essential role of OGT in regulating β-cell mitochondrial morphology and bioenergetics. In conclusion, OGT couples nutrient signal and mitochondrial function to promote normal β-cell physiology. <br>

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The intestine responds to heart failure by enhanced mitochondrial fusion through glucagon-like peptide-1 signalling

Cardiovascular Research ◽

10.1093/cvr/cvz002 ◽

2019 ◽

Vol 115 (13) ◽

pp. 1873-1885 ◽

Cited By ~ 3

Author(s):

Genki Naruse ◽

Hiromitsu Kanamori ◽

Akihiro Yoshida ◽

Shingo Minatoguchi ◽

Tomonori Kawaguchi ◽

...

Keyword(s):

Heart Failure ◽

Cardiac Dysfunction ◽

Mitochondrial Dynamics ◽

Left Ventricular ◽

Mitochondrial Fusion ◽

Mitochondrial Morphology ◽

Atp Content ◽

Glucagon Like Peptide ◽

Glucagon Like Peptide 1 ◽

The Impact

Abstract Aims Glucagon-like peptide-1 (GLP-1) is a neuroendocrine hormone secreted by the intestine. Its receptor (GLP-1R) is expressed in various organs, including the heart. However, the dynamics and function of the GLP-1 signal in heart failure remains unclear. We investigated the impact of the cardio-intestinal association on hypertensive heart failure using miglitol, an α-glucosidase inhibitor known to stimulate intestinal GLP-1 production. Methods and results Dahl salt-sensitive (DS) rats fed a high-salt diet were assigned to miglitol, exendin (9-39) (GLP-1R blocker) and untreated control groups and treated for 11 weeks. Control DS rats showed marked hypertension and cardiac dysfunction with left ventricular dilatation accompanied by elevated plasma GLP-1 levels and increased cardiac GLP-1R expression as compared with age-matched Dahl salt-resistant (DR) rats. Miglitol further increased plasma GLP-1 levels, suppressed adverse cardiac remodelling, and mitigated cardiac dysfunction. In cardiomyocytes from miglitol-treated DS hearts, mitochondrial size was significantly larger with denser cristae than in cardiomyocytes from control DS hearts. The change in mitochondrial morphology reflected enhanced mitochondrial fusion mediated by protein kinase A activation leading to phosphorylation of dynamin-related protein 1, expression of mitofusin-1 and OPA-1, and increased myocardial adenosine triphosphate (ATP) content. GLP-1R blockade with exendin (9-39) exacerbated cardiac dysfunction and led to fragmented mitochondria with disarrayed cristae in cardiomyocytes and reduction of myocardial ATP content. In cultured cardiomyocytes, GLP-1 increased expression of mitochondrial fusion-related proteins and ATP content. When GLP-1 and exendin (9-39) were administered together, their effects cancelled out. Conclusions Increased intestinal GLP-1 secretion is an adaptive response to heart failure that is enhanced by miglitol. This could be an effective strategy for treating heart failure through regulation of mitochondrial dynamics.

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