scholarly journals Structural insights of human mitofusin-2 into mitochondrial fusion and CMT2A onset

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Yu-Jie Li ◽  
Yu-Lu Cao ◽  
Jian-Xiong Feng ◽  
Yuanbo Qi ◽  
Shuxia Meng ◽  
...  
Keyword(s):  
Cell Metabolism ◽  
Mitochondrial Fusion ◽  
Single Amino Acid ◽  
Dependent Manner ◽  
Gtp Hydrolysis ◽  
Mitofusin 2 ◽  
Membrane Tethering ◽  
Functional Zones ◽  
Tooth Type ◽  
Fundamental Insight

Abstract Mitofusin-2 (MFN2) is a dynamin-like GTPase that plays a central role in regulating mitochondrial fusion and cell metabolism. Mutations in MFN2 cause the neurodegenerative disease Charcot-Marie-Tooth type 2A (CMT2A). The molecular basis underlying the physiological and pathological relevance of MFN2 is unclear. Here, we present crystal structures of truncated human MFN2 in different nucleotide-loading states. Unlike other dynamin superfamily members including MFN1, MFN2 forms sustained dimers even after GTP hydrolysis via the GTPase domain (G) interface, which accounts for its high membrane-tethering efficiency. The biochemical discrepancy between human MFN2 and MFN1 largely derives from a primate-only single amino acid variance. MFN2 and MFN1 can form heterodimers via the G interface in a nucleotide-dependent manner. CMT2A-related mutations, mapping to different functional zones of MFN2, lead to changes in GTP hydrolysis and homo/hetero-association ability. Our study provides fundamental insight into how mitofusins mediate mitochondrial fusion and the ways their disruptions cause disease.

scholarly journals Mitochondrial fusion and function in Charcot–Marie–Tooth type 2A patient fibroblasts with mitofusin 2 mutations

2008 ◽  
Vol 211 (1) ◽  
pp. 115-127 ◽  
Author(s):  
Elizabeth A. Amiott ◽  
Paul Lott ◽  
Jamie Soto ◽  
Peter B. Kang ◽  
J. Michael McCaffery ◽  
...  
Keyword(s):  
Mitochondrial Fusion ◽  
Mitofusin 2 ◽  
Charcot Marie Tooth ◽  
Tooth Type ◽  
And Function

Orexin system is expressed in avian muscle cells and regulates mitochondrial dynamics

2015 ◽  
Vol 308 (3) ◽  
pp. R173-R187 ◽  
Author(s):  
Kentu Lassiter ◽  
Elizabeth Greene ◽  
Alissa Piekarski ◽  
Olivia B. Faulkner ◽  
Billy M. Hargis ◽  
...  
Keyword(s):  
Mitochondrial Dynamics ◽  
Muscle Cells ◽  
Secretory Protein ◽  
Mitochondrial Fusion ◽  
High Dose ◽  
Dependent Manner ◽  
Orexin A ◽  
Mitofusin 2 ◽  
Avian Muscle

Orexin A and B, orexigenic peptides produced primarily by the lateral hypothalamus that signal through two G protein-coupled receptors, orexin receptors 1/2, have been implicated in the regulation of several physiological processes in mammals. In avian (nonmammalian vertebrates) species; however, the physiological roles of orexin are not well defined. Here, we provide novel evidence that not only is orexin and its related receptors 1/2 (ORXR1/2) expressed in chicken muscle tissue and quail muscle (QM7) cell line, orexin appears to be a secretory protein in QM7 cells. In vitro administration of recombinant orexin A and B (rORX-A and B) differentially regulated prepro-orexin expression in a dose-dependent manner with up-regulation for rORX-A ( P < 0.05) and downregulation for rORX-B ( P < 0.05) in QM7 cells. While both peptides upregulated ORXR1 expression, only a high dose of rORX-B decreased the expression of ORXR2 ( P < 0.05). The presence of orexin and its related receptors and the regulation of its own system in avian muscle cells indicate that orexin may have autocrine, paracrine, and/or endocrine roles. rORXs differentially regulated mitochondrial dynamics network. While rORX-A significantly induced the expression of mitochondrial fission-related genes ( DNM1, MTFP1, MTFR1), rORX-B increased the expression of mitofusin 2, OPA1, and OMA1 genes that are involved in mitochondrial fusion. Concomitant with these changes, rORXs differentially regulated the expression of several mitochondrial metabolic genes ( av-UCP, av-ANT, Ski, and NRF-1) and their related transcriptional regulators ( PPARγ, PPARα, PGC-1α, PGC-1β, and FoxO-1) without affecting ATP synthesis. Taken together, our data represent the first evidence of the presence and secretion of orexin system in the muscle of nonmammalian species and its role in mitochondrial fusion and fission, probably through mitochondrial-related genes and their related transcription factors.

scholarly journals Small molecule induces mitochondrial fusion for neuroprotection via targeting CK2 without affecting its conventional kinase activity

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Ke-Wu Zeng ◽  
Jing-Kang Wang ◽  
Li-Chao Wang ◽  
Qiang Guo ◽  
Ting-Ting Liu ◽  
...  
Keyword(s):  
Small Molecule ◽  
Nuclear Translocation ◽  
Fusion Gene ◽  
Artery Occlusion ◽  
Mitochondrial Fusion ◽  
Dependent Manner ◽  
Behavioral Deficits ◽  
Α Subunit ◽  
Cellular Target ◽  
Cerebral Artery Occlusion

AbstractMitochondrial fusion/fission dynamics plays a fundamental role in neuroprotection; however, there is still a severe lack of therapeutic targets for this biological process. Here, we found that the naturally derived small molecule echinacoside (ECH) significantly promotes mitochondrial fusion progression. ECH selectively binds to the previously uncharacterized casein kinase 2 (CK2) α′ subunit (CK2α′) as a direct cellular target, and genetic knockdown of CK2α′ abolishes ECH-mediated mitochondrial fusion. Mechanistically, ECH allosterically regulates CK2α′ conformation to recruit basic transcription factor 3 (BTF3) to form a binary protein complex. Then, the CK2α′/BTF3 complex facilitates β-catenin nuclear translocation to activate TCF/LEF transcription factors and stimulate transcription of the mitochondrial fusion gene Mfn2. Strikingly, in a mouse middle cerebral artery occlusion (MCAO) model, ECH administration was found to significantly improve cerebral injuries and behavioral deficits by enhancing Mfn2 expression in wild-type but not CK2α′+/− mice. Taken together, our findings reveal, for the first time, that CK2 is essential for promoting mitochondrial fusion in a Wnt/β-catenin-dependent manner and suggest that pharmacologically targeting CK2 is a promising therapeutic strategy for ischemic stroke.

Abstract 16939: Metabolic and Electrophysiological Alterations Underlie Proarrhythmic Properties of Highly Reactive Isolevuglandins in Atrial Cardiomyocytes

Circulation ◽  
2020 ◽  
Vol 142 (Suppl_3) ◽  
Author(s):  
Tuerdi Subati ◽  
Zhenjiang Yang ◽  
Isis L Christopher ◽  
Joseph C Van Amburg ◽  
Matthew B Murphy ◽  
...  
Keyword(s):  
Membrane Potential ◽  
High Throughput Screening ◽  
Cell Metabolism ◽  
Resting Membrane Potential ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Atp Production ◽  
Atrial Cardiomyocytes ◽  
Extracellular Flux ◽  
Mitochondrial Transition Pore

Background: Hypertension is one of the most common risk factors for atrial fibrillation (AF), although the precise cellular and molecular mechanism(s) by which hypertension leads to AF are not well understood. Isolevuglandins (IsoLGs) are highly reactive dicarbonyl products of lipid peroxidation responsible for a major component of oxidative stress-related injury. In a mouse model of hypertension, we recently demonstrated that IsoLGs are elevated in hypertensive mouse atria and that an IsoLG scavenger reduced both IsoLG burden and AF susceptibility. Hypothesis: In this study, we hypothesized that IsoLGs can promote AF by inducing proarrhythmic metabolic and electrophysiologic (EP) changes in atrial cardiomyocytes. Methods and Results: Using standard patch clamp methods, we found significant changes in action potential properties of isolated mouse atrial cardiomyocytes exposed to IsoLGs (1μM, n=15 cells), including elevation of resting membrane potential, shortening of APD and reduction of V max . Acute IsoLG treatment led to a reduction of intracellular ATP production in atrial HL-1 cardiomyocytes, as measured by using a luminescence assay. Employing TMRM and Mitotracker Green staining for confocal and high-throughput screening (HTS) live-cell imaging assays, we also found that IsoLGs decreased mitochondrial membrane potential (compared to control, TMRM fluorescence decreased by 23%, 28%, 36% and 42%, respectively, when exposed to 0.01, 0.1, 0.5 and 1μM concentrations of IsoLG) accompanied by increased apoptosis (Cell Event Caspase-3/7 Green Detection Reagent) in a concentration-dependent manner, suggesting a prolonged mitochondrial transition pore opening. Moreover, cell metabolism assays performed using Agilent’s Seahorse XF96 extracellular flux analyzer revealed that IsoLGs exert a concentration dependent decrease in basal oxygen consumption rate and ATP production in HL-1 atrial cardiomyocytes. Conclusion: Together, these findings indicate that IsoLGs promote proarrhythmic EP and mitochondrial effects in atrial cells and thus may provide a novel therapeutic target for AF.

scholarly journals Muscle Hyperplasia in Japanese Quail by Single Amino Acid Deletion in MSTN Propeptide

2020 ◽  
Vol 21 (4) ◽  
pp. 1504 ◽  
Author(s):  
Joonbum Lee ◽  
Dong-Hwan Kim ◽  
Kichoon Lee
Keyword(s):  
Muscle Mass ◽  
Gene Knockout ◽  
Muscle Growth ◽  
Avian Species ◽  
Negative Regulator ◽  
Single Amino Acid ◽  
Heart Weight ◽  
Dependent Manner ◽  
Base Pair Deletion ◽  
Muscle Hyperplasia

Mutation in myostatin (MSTN), a negative regulator of muscle growth in skeletal muscle, resulted in increased muscle mass in mammals and fishes. However, MSTN mutation in avian species has not been reported. The objective of this study was to generate MSTN mutation in quail and investigate the effect of MSTN mutation in avian muscle growth. Recently, a new targeted gene knockout approach for the avian species has been developed using an adenoviral CRISPR/Cas9 system. By injecting the recombinant adenovirus containing CRISPR/Cas9 into the quail blastoderm, potential germline chimeras were generated and offspring with three base-pair deletion in the targeted region of the MSTN gene was identified. This non-frameshift mutation in MSTN resulted in deletion of cysteine 42 in the MSTN propeptide region and homozygous mutant quail showed significantly increased body weight and muscle mass with muscle hyperplasia compared to heterozygous mutant and wild-type quail. In addition, decreased fat pad weight and increased heart weight were observed in MSTN mutant quail in an age- and sex-dependent manner, respectively. Taken together, these data indicate anti-myogenic function of MSTN in the avian species and the importance of cysteine 42 in regulating MSTN function.

scholarly journals Complex Response of the CpxAR Two-Component System to β-Lactams on Antibiotic Resistance and Envelope Homeostasis in Enterobacteriaceae

2020 ◽  
Vol 64 (6) ◽  
Author(s):  
Muriel Masi ◽  
Elizabeth Pinet ◽  
Jean-Marie Pagès
Keyword(s):  
Efflux Pump ◽  
Multidrug Resistant ◽  
Diaminopimelic Acid ◽  
Single Amino Acid ◽  
Dependent Manner ◽  
Content Type ◽  
Promising Therapeutic Target ◽  
Abnormal Accumulation ◽  
A Cell ◽  
Mutational Activation

ABSTRACT The Cpx stress response is widespread among Enterobacteriaceae. We previously reported a mutation in cpxA in a multidrug-resistant strain of Klebsiella aerogenes isolated from a patient treated with imipenem. This mutation yields a single-amino-acid substitution (Y144N) located in the periplasmic sensor domain of CpxA. In this work, we sought to characterize this mutation in Escherichia coli by using genetic and biochemical approaches. Here, we show that cpxAY144N is an activated allele that confers resistance to β-lactams and aminoglycosides in a CpxR-dependent manner, by regulating the expression of the OmpF porin and the AcrD efflux pump, respectively. We also demonstrate the effect of the intimate interconnection between the Cpx system and peptidoglycan integrity on the expression of an exogenous AmpC β-lactamase by using imipenem as a cell wall-active antibiotic or by inactivating penicillin-binding proteins. Moreover, our data indicate that the Y144N substitution abrogates the interaction between CpxA and CpxP and increases phosphotransfer activity on CpxR. Because the addition of a strong AmpC inducer such as imipenem is known to cause abnormal accumulation of muropeptides (disaccharide-pentapeptide and N-acetylglucosamyl-1,6-anhydro-N-acetylmuramyl-l-alanyl-d-glutamy-meso-diaminopimelic-acid-d-alanyl-d-alanine) in the periplasmic space, we propose these molecules activate the Cpx system by displacing CpxP from the sensor domain of CpxA. Altogether, these data could explain why large perturbations to peptidoglycans caused by imipenem lead to mutational activation of the Cpx system and bacterial adaptation through multidrug resistance. These results also validate the Cpx system, in particular, the interaction between CpxA and CpxP, as a promising therapeutic target.

Abscisic acid induction of GTP hydrolysis in maize coleoptile plasma membranes

1998 ◽  
Vol 25 (5) ◽  
pp. 539 ◽  
Author(s):  
Helen R. Irving
Keyword(s):  
Abscisic Acid ◽  
G Protein ◽  
G Proteins ◽  
Pertussis Toxin ◽  
Plasma Membranes ◽  
Dependent Manner ◽  
Gtpase Activity ◽  
Heterotrimeric G Proteins ◽  
Gtp Hydrolysis ◽  
Maize Coleoptile

Since receptor-coupled G proteins increase GTP hydrolysis (GTPase) activity upon ligands binding to the receptor, a study was undertaken to determine if abscisic acid (ABA) induced such an effect. Plasma membranes isolated from etiolated maize (Zea mays L.) coleoptiles were enriched in GTPase activity relative to microsomal fractions. Vanadate was included in the assay to inhibit the high levels of vanadate sensitive low affinity GTPases present. Under these conditions, GTPase activity was enhanced by Mg2+, stimulated by mastoparan, and inhibited by GTPγS indicating the presence of either monomeric or heterotrimeric G proteins. The combination of NaF and AlCl3 is expected to inhibit heterotrimeric G protein activity but had little effect on GTPase activity in maize coleoptile membranes. Cholera toxin enhanced basal GTPase activity, confirming the presence of heterotrimeric G proteins in maize plasma membranes. Pertussis toxin also slightly enhanced basal GTPase activity in maize membranes. Abscisic acid enhanced GTPase activity optimally at 5 mmol/L Mg2+ in a concentration dependent manner by 1.5-fold at 10 µmol/L and up to three-fold at 100 µmol/L ABA. Abscisic acid induced GTPase activity was inhibited by GTPγS, the combination of NaF and AlCl3, and pertussis toxin. Overall, these results are typical of a receptor-coupled G protein responding to its ligand.

Membrane Nanoparticles Derived from ACE2-rich Cells Block SARS-CoV-2 Infection

2020 ◽  
Author(s):  
Cheng Wang ◽  
Shaobo Wang ◽  
Yin Chen ◽  
Jianqi Zhao ◽  
Songling Han ◽  
...  
Keyword(s):  
Viral Entry ◽  
Inhibitory Concentration ◽  
Cell Metabolism ◽  
Host Cells ◽  
Dependent Manner ◽  
Human Embryonic Kidney ◽  
Proximal Tubular Cells ◽  
Tubular Cells ◽  
Proximal Tubular ◽  
Dose Dependent

ABSTRACTThe ongoing COVID-19 epidemic worldwide necessitates the development of novel effective agents against SARS-CoV-2. ACE2 is the main receptor of SARS-CoV-2 S1 protein and mediates viral entry into host cells. Herein, the membrane nanoparticles prepared from ACE2-rich cells are discovered with potent capacity to block SARS-CoV-2 infection. The membrane of human embryonic kidney-239T cell highly expressing ACE2 is screened to prepare nanoparticles. The nanomaterial termed HEK-293T-hACE2 NPs contains 265.1 ng mg−1 of ACE2 on the surface and acts as a bait to trap SARS-CoV-2 S1 in a dose-dependent manner, resulting in reduced recruitment of the viral ligand to host cells. Interestingly, SARS-CoV-2 S1 can translocate to the cytoplasm and affect the cell metabolism, which is also inhibited by HEK-293T-hACE2 NPs. Further studies reveal that HEK-293T-hACE2 NPs can efficiently suppress SARS-CoV-2 S pseudovirions entry into human proximal tubular cells and block viral infection with a low half maximal inhibitory concentration. Additionally, this biocompatible membrane nanomaterial is sufficient to block the adherence of SARS-CoV-2 D614G-S1 mutant to sensitive cells. Our study demonstrates a easy-to-acheive memrbane nano-antagonist for curbing SARS-CoV-2, which enriches the existing antiviral arsenal and provides new possibilities to treat COVID-19. Graphical Table of Contents

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