MARCH‐V is a novel mitofusin 2‐ and Drp1‐binding protein able to change mitochondrial morphology

Sequence variants in vacuolar protein sorting 35 (VPS35) have been reported to be associated with Parkinson’s disease (PD). To investigate if the genetic variants in VPS35 contribute to Taiwanese PD, VPS35 cDNA fragments from 62 patients with PD were sequenced. A cohort of PD (n = 560) and ethnically matched controls (n = 506) were further examined for the identified mutation. The effects of the mutation on cation-independent mannose-6-phosphate receptor (CI-MPR) sorting and mitochondrial morphology were further examined in 293T cells expressing the mutant VPS35. Here, a novel heterozygous A320V in the VPS35 gene was identified in two late-onset PD (LOPD) patients, which was absent in 506 normal controls. Expression of the A320V mutant in 293T cells demonstrated increased colocalization of VPS35 with CI-MPR and decreased CI-MPR and lysosomal-associated membrane protein 2 (LAMP2) levels. Decreased CI-MPR manifested in missorting of cathepsin D and decreased proteolysis of α-synuclein. A320V mutation also increased mitochondrial E3 ubiquitin protein ligase 1 (MUL1) and thus led to mitofusin 2 (MFN2) degradation. The results suggest that the expression of VPS35 A320V leads to disrupted CI-MPR sorting and impaired mitochondrial morphology, which may partly explain its action in PD.

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Cardiomyocyte deletion of mitofusin-1 leads to mitochondrial fragmentation and improves tolerance to ROS-induced mitochondrial dysfunction and cell death

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.00833.2011 ◽

2012 ◽

Vol 302 (1) ◽

pp. H167-H179 ◽

Cited By ~ 113

Author(s):

Kyriakos N. Papanicolaou ◽

Gladys A. Ngoh ◽

Erinne R. Dabkowski ◽

Kelly A. O'Connell ◽

Rogerio F. Ribeiro ◽

...

Keyword(s):

Mitochondrial Dysfunction ◽

Mitochondrial Permeability Transition ◽

Microscopic Analysis ◽

Left Ventricular ◽

Mitochondrial Morphology ◽

Mitochondrial Fragmentation ◽

Electron Microscopic ◽

Mitofusin 2 ◽

The Impact

Molecular studies examining the impact of mitochondrial morphology on the mammalian heart have previously focused on dynamin related protein-1 (Drp-1) and mitofusin-2 (Mfn-2), while the role of the other mitofusin isoform, Mfn-1, has remained largely unexplored. In the present study, we report the generation and initial characterization of cardiomyocyte-specific Mfn-1 knockout (Mfn-1 KO) mice. Using electron microscopic analysis, we detect a greater prevalence of small, spherical mitochondria in Mfn-1 KO hearts, indicating that the absence of Mfn-1 causes a profound shift in the mitochondrial fusion/fission balance. Nevertheless, Mfn-1 KO mice exhibit normal left-ventricular function, and isolated Mfn-1 KO heart mitochondria display a normal respiratory repertoire. Mfn-1 KO myocytes are protected from mitochondrial depolarization and exhibit improved viability when challenged with reactive oxygen species (ROS) in the form of hydrogen peroxide (H2O2). Furthermore, in vitro studies detect a blunted response of KO mitochondria to undergo peroxide-induced mitochondrial permeability transition pore opening. These data suggest that Mfn-1 deletion confers protection against ROS-induced mitochondrial dysfunction. Collectively, we suggest that mitochondrial fragmentation in myocytes is not sufficient to induce heart dysfunction or trigger cardiomyocyte death. Additionally, our data suggest that endogenous levels of Mfn-1 can attenuate myocyte viability in the face of an imminent ROS overload, an effect that could be associated with the ability of Mfn-1 to remodel the outer mitochondrial membrane.

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The Protective Effect of Alpha-Mangostin against Cisplatin-Induced Cell Death in LLC-PK1 Cells is Associated to Mitochondrial Function Preservation

Antioxidants ◽

10.3390/antiox8050133 ◽

2019 ◽

Vol 8 (5) ◽

pp. 133 ◽

Cited By ~ 8

Author(s):

Laura María Reyes-Fermín ◽

Sabino Hazael Avila-Rojas ◽

Omar Emiliano Aparicio-Trejo ◽

Edilia Tapia ◽

Isabel Rivero ◽

...

Keyword(s):

Cell Death ◽

Mitochondrial Function ◽

Anion Channel ◽

Laboratory Culture ◽

Mitochondrial Morphology ◽

Protective Effects ◽

Mitofusin 2 ◽

Mitochondrial Mass ◽

Protein Levels ◽

Function Preservation

Cis-dichlorodiammineplatinum II (CDDP) is a chemotherapeutic agent that induces nephrotoxicity by different mechanisms, including oxidative stress, mitochondrial dysfunction, autophagy, and endoplasmic reticulum stress. This study aimed to evaluate if the protective effects of the antioxidant alpha-mangostin (αM) in CDDP-induced damage in proximal tubule Lilly laboratory culture porcine kidney (LLC-PK1) cells, are related to mitochondrial function preservation. It was found that αM co-incubation prevented CDDP-induced cell death. Furthermore, αM prevented the CDDP-induced decrease in cell respiratory states, in the maximum capacity of the electron transfer system (E) and in the respiration associated to oxidative phosphorylation (OXPHOS). CDDP also decreased the protein levels of voltage dependence anion channel (VDAC) and mitochondrial complex subunits, which together with the reduction in E, the mitofusin 2 decrease and the mitochondrial network fragmentation observed by MitoTracker Green, suggest the mitochondrial morphology alteration and the decrease in mitochondrial mass induced by CDDP. CDDP also induced the reduction in mitochondrial biogenesis observed by transcription factor A, mitochondria (TFAM) decreased protein-level and the increase in mitophagy. All these changes were prevented by αM. Taken together, our results imply that αM’s protective effects in CDDP-induced toxicity in LLC-PK1 cells are associated to mitochondrial function preservation.

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Regulation of mitochondrial morphology and cell survival by Mitogenin I and mitochondrial single-stranded DNA binding protein

Biochimica et Biophysica Acta (BBA) - General Subjects ◽

10.1016/j.bbagen.2006.05.012 ◽

2006 ◽

Vol 1760 (9) ◽

pp. 1364-1372 ◽

Cited By ~ 26

Author(s):

Naokatu Arakaki ◽

Takeshi Nishihama ◽

Akira Kohda ◽

Hiroyuki Owaki ◽

Yoshinori Kuramoto ◽

...

Keyword(s):

Dna Binding ◽

Cell Survival ◽

Binding Protein ◽

Dna Binding Protein ◽

Mitochondrial Morphology ◽

Single Stranded Dna

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Analysis of Mitochondrial Morphology and Function Under Conditions of Mitofusin 2 Deficiency

Methods in Molecular Biology - Mitochondrial Medicine ◽

10.1007/978-1-4939-2288-8_21 ◽

2015 ◽

pp. 307-320 ◽

Cited By ~ 5

Author(s):

Juan Pablo Muñoz ◽

Antonio Zorzano

Keyword(s):

Mitochondrial Morphology ◽

Mitofusin 2 ◽

And Function

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Mitofusin 2 attenuates the histone acetylation at collagen IV promoter in diabetic nephropathy

Journal of Molecular Endocrinology ◽

10.1530/jme-16-0031 ◽

2016 ◽

Vol 57 (4) ◽

pp. 233-249 ◽

Cited By ~ 2

Author(s):

Xuhua Mi ◽

Wanxin Tang ◽

Xiaolei Chen ◽

Fei Liu ◽

Xiaohong Tang

Keyword(s):

Diabetic Nephropathy ◽

Mitochondrial Dysfunction ◽

Histone Acetylation ◽

Molecular Mechanisms ◽

Mesangial Cells ◽

Collagen Iv ◽

Mitochondrial Morphology ◽

Glomerular Mesangial Cells ◽

Mitofusin 2 ◽

Protective Function

Extracellular matrix (ECM) increase in diabetic nephropathy (DN) is closely related to mitochondrial dysfunction. The mechanism of protective function of mitofusin 2 (Mfn2) for mitochondria remains largely unknown. In this study, the molecular mechanisms for the effect of Mfn2 on mitochondria and subsequent collagen IV expression in DN were investigated. Ras-binding-deficient mitofusin 2 (Mfn2–Ras(Δ)) were overexpressed in rat glomerular mesangial cells, and then the cells were detected for mitochondrial morphology, cellular reactive oxygen species (ROS), mRNA and protein expression of collagen IV with advanced glycation end-product (AGE) stimulation. Preliminary results reveal that the mitochondrial dysfunction and the increased synthesis of collagen IV after AGE stimulation were reverted by Mfn2–Ras(Δ) overexpression. Bioinformatical computations were performed to search transcriptional factor motifs in the promoter region of collagen IV. Three specific regions for TFAP2A binding were identified, followed by validation with chromatin immunoprecipitation experiments. Knocking down TFAP2A significantly decreased the TF binding in the first two regions and the gene expression of collagen IV. Furthermore, results reveal that Mfn2–Ras(Δ) overexpression significantly mitigated TFAP2A binding and also reverted the histone acetylation at Regions 1 and 2 after AGE stimulation. In streptozotocin-induced diabetic rats, Mfn2–Ras(Δ) overexpression also ameliorated glomerular mesangial lesions with decreased collagen IV expression, accompanied by decreased acetylation and TFAP2A binding at Region 1. In conclusion, this study highlights the pathway by which mitochondria affect the histone acetylation of gene promoter and provides a new potential therapy approach for DN.

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Cerebrovascular function and mitochondrial bioenergetics after ischemia-reperfusion in male rats

Journal of Cerebral Blood Flow & Metabolism ◽

10.1177/0271678x17745028 ◽

2017 ◽

Vol 39 (6) ◽

pp. 1056-1068 ◽

Cited By ~ 10

Author(s):

Ibolya Rutkai ◽

Ivan Merdzo ◽

Sanjay V Wunnava ◽

Genevieve T Curtin ◽

Prasad VG Katakam ◽

...

Keyword(s):

Ischemia Reperfusion ◽

Cerebral Arteries ◽

Male Rats ◽

Mitochondrial Morphology ◽

Sprague Dawley ◽

Mitofusin 2 ◽

Cerebrovascular Function ◽

Sprague Dawley Rats ◽

Activity Measurements ◽

And Function

The underlying factors promoting increased mitochondrial proteins, mtDNA, and dilation to mitochondrial-specific agents in male rats following tMCAO are not fully elucidated. Our goal was to determine the morphological and functional effects of ischemia/reperfusion (I/R) on mitochondria using electron microscopy, Western blot, mitochondrial oxygen consumption rate (OCR), and Ca2+ sparks activity measurements in middle cerebral arteries (MCAs) from male Sprague Dawley rats (Naïve, tMCAO, Sham). We found a greatly increased OCR in ipsilateral MCAs (IPSI) compared with contralateral (CONTRA), Sham, and Naïve MCAs. Consistent with our earlier findings, the expression of Mitofusin-2 and OPA-1 was significantly decreased in IPSI arteries compared with Sham and Naïve. Mitochondrial morphology was disrupted in vascular smooth muscle, but morphology with normal and perhaps greater numbers of mitochondria were observed in IPSI compared with CONTRA MCAs. Consistently, there were significantly fewer baseline Ca2+ events in IPSI MCAs compared with CONTRA, Sham, and Naïve. Mitochondrial depolarization significantly increased Ca2+ sparks activity in the IPSI, Sham, Naïve, but not in the CONTRA group. Our data indicate that altered mitochondrial structure and function occur in MCAs exposed to I/R and that these changes impact not only OCR but Ca2+ sparks activity in both IPSI and CONTRA MCAs.

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Human biallelic MFN2 mutations induce mitochondrial dysfunction, upper body adipose hyperplasia, and suppression of leptin expression

eLife ◽

10.7554/elife.23813 ◽

2017 ◽

Vol 6 ◽

Cited By ~ 21

Author(s):

Nuno Rocha ◽

David A Bulger ◽

Andrea Frontini ◽

Hannah Titheradge ◽

Sigrid Bjerge Gribsholt ◽

...

Keyword(s):

Mitochondrial Dysfunction ◽

Axonal Neuropathy ◽

Upper Body ◽

Mitochondrial Morphology ◽

Mitofusin 2 ◽

Excess Adiposity ◽

Affected Tissue ◽

Membrane Bound ◽

Organelle Communication ◽

Leptin Expression

MFN2 encodes mitofusin 2, a membrane-bound mediator of mitochondrial membrane fusion and inter-organelle communication. MFN2 mutations cause axonal neuropathy, with associated lipodystrophy only occasionally noted, however homozygosity for the p.Arg707Trp mutation was recently associated with upper body adipose overgrowth. We describe similar massive adipose overgrowth with suppressed leptin expression in four further patients with biallelic MFN2 mutations and at least one p.Arg707Trp allele. Overgrown tissue was composed of normal-sized, UCP1-negative unilocular adipocytes, with mitochondrial network fragmentation, disorganised cristae, and increased autophagosomes. There was strong transcriptional evidence of mitochondrial stress signalling, increased protein synthesis, and suppression of signatures of cell death in affected tissue, whereas mitochondrial morphology and gene expression were normal in skin fibroblasts. These findings suggest that specific MFN2 mutations cause tissue-selective mitochondrial dysfunction with increased adipocyte proliferation and survival, confirm a novel form of excess adiposity with paradoxical suppression of leptin expression, and suggest potential targeted therapies.

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Back to The Fusion: Mitofusin-2 in Alzheimer’s Disease

Journal of Clinical Medicine ◽

10.3390/jcm9010126 ◽

2020 ◽

Vol 9 (1) ◽

pp. 126 ◽

Cited By ~ 2

Author(s):

Giulia Sita ◽

Patrizia Hrelia ◽

Agnese Graziosi ◽

Fabiana Morroni

Keyword(s):

Alzheimer’S Disease ◽

Alzheimer's Disease ◽

Endoplasmic Reticulum ◽

Mitochondrial Dynamics ◽

Mitochondrial Morphology ◽

Mitochondria Dysfunction ◽

Mitofusin 2 ◽

Essential Information ◽

Human Disorders

Mitochondria are dynamic organelles that undergo constant fission and fusion. Mitochondria dysfunction underlies several human disorders, including Alzheimer’s disease (AD). Preservation of mitochondrial dynamics is fundamental for regulating the organelle’s functions. Several proteins participate in the regulation of mitochondrial morphology and networks, and among these, Mitofusin 2 (Mfn2) has been extensively studied. This review focuses on the role of Mfn2 in mitochondrial dynamics and in the crosstalk between mitochondria and the endoplasmic reticulum, in particular in AD. Understanding how this protein may be related to AD pathogenesis will provide essential information for the development of therapies for diseases linked to disturbed mitochondrial dynamics, as in AD.

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A form of mitofusin 2 (Mfn2) lacking the transmembrane domains and the COOH-terminal end stimulates metabolism in muscle and liver cells

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.00546.2012 ◽

2013 ◽

Vol 305 (10) ◽

pp. E1208-E1221 ◽

Cited By ~ 17

Author(s):

Jessica Segalés ◽

José C. Paz ◽

María Isabel Hernández-Alvarez ◽

David Sala ◽

Juan Pablo Muñoz ◽

...

Keyword(s):

Skeletal Muscle ◽

Mitochondrial Dynamics ◽

Coiled Coil ◽

Respiratory Control ◽

Liver Cells ◽

Transmembrane Domains ◽

Mitochondrial Fusion ◽

Metabolic Effects ◽

Mitochondrial Morphology ◽

Mitofusin 2

Mitofusin 2 (Mfn2), a protein that participates in mitochondrial fusion, is required to maintain normal mitochondrial metabolism in skeletal muscle and liver. Given that muscle Mfn2 is repressed in obese or type 2 diabetic subjects, this protein may have a potential pathophysiological role in these conditions. To evaluate whether the metabolic effects of Mfn2 can be dissociated from its function in mitochondrial dynamics, we studied a form of human Mfn2, lacking the two transmembrane domains and the COOH-terminal coiled coil (ΔMfn2). This form localized in mitochondria but did not alter mitochondrial morphology in cells or in skeletal muscle fibers. The expression of ΔMfn2 in mouse skeletal muscle stimulated glucose oxidation and enhanced respiratory control ratio, which occurred in the absence of changes in mitochondrial mass. ΔMfn2 did not stimulate mitochondrial respiration in Mfn2-deficient muscle cells. The expression of ΔMfn2 in mouse liver or in hepatoma cells stimulated gluconeogenesis. In addition, ΔMfn2 activated basal and maximal respiration both in muscle and liver cells. In all, we show that a form of Mfn2 lacking mitochondrial fusion activity stimulates mitochondrial function and enhances glucose metabolism in muscle and liver tissues. This study suggests that Mfn2 regulates metabolism independently of changes in mitochondrial morphology.

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