scholarly journals Cex1 is a component of the COPI intracellular trafficking machinery

Biology Open ◽  
2021 ◽  
Vol 10 (3) ◽  
Author(s):  
Ludovic Enkler ◽  
Bruno Rinaldi ◽  
Johan Owen de Craene ◽  
Philippe Hammann ◽  
Osamu Nureki ◽  
...  
Keyword(s):  
Neurodegenerative Disorders ◽  
Intracellular Trafficking ◽  
Complex I ◽  
Mammalian Cells ◽  
Deletion Mutant ◽  
Protein Glycosylation ◽  
Coated Vesicles ◽  
Human Homologue ◽  
Membrane Compartments ◽  
Mutant Cells

ABSTRACT COPI (coatomer complex I) coated vesicles are involved in Golgi-to-ER and intra-Golgi trafficking pathways, and mediate retrieval of ER resident proteins. Functions and components of the COPI-mediated trafficking pathways, beyond the canonical set of Sec/Arf proteins, are constantly increasing in number and complexity. In mammalian cells, GORAB, SCYL1 and SCYL3 proteins regulate Golgi morphology and protein glycosylation in concert with the COPI machinery. Here, we show that Cex1, homologous to the mammalian SCYL proteins, is a component of the yeast COPI machinery, by interacting with Sec27, Sec28 and Sec33 (Ret1/Cop1) proteins of the COPI coat. Cex1 was initially reported to mediate channeling of aminoacylated tRNA outside of the nucleus. Our data show that Cex1 localizes at membrane compartments, on structures positive for the Sec33 α-COP subunit. Moreover, the Wbp1 protein required for N-glycosylation and interacting via its di-lysine motif with the Sec27 β′-COP subunit is mis-targeted in cex1Δ deletion mutant cells. Our data point to the possibility of developing Cex1 yeast-based models to study neurodegenerative disorders linked to pathogenic mutations of its human homologue SCYL1.

scholarly journals Cex1 is a new component of the COPI Golgi-to-vacuole intracellular trafficking machinery

2018 ◽  
Author(s):  
Ludovic Enkler ◽  
Johann Owen de Craene ◽  
Bruno Rinaldi ◽  
Philippe Hammann ◽  
Osamu Nureki ◽  
...  
Keyword(s):  
Neurodegenerative Disorders ◽  
Intracellular Trafficking ◽  
Complex I ◽  
Fluorescent Microscopy ◽  
Nuclear Periphery ◽  
Interacting Proteins ◽  
Trafficking Pathway ◽  
Sorting Receptor ◽  
Vacuolar Protein ◽  
Golgi Network

AbstractDuring translational elongation, aminoacylated tRNA are supplied to the ribosome by RNA-interacting proteins. Cex1, a HEAT-containing protein, has been shown to participate to this tRNA channeling by interacting with aminoacylated tRNA during their export from the nucleus. Here, we show that Cex1 is a component of COPI (coatomer complex I) coated vesicles involved in the Golgi-to-vacuole trafficking pathway in Saccharomyces cerevisiae. Cex1 interacts with key components of the COPI coat Sec27, Sec28 and Sec33 proteins. Moreover, fluorescent microscopy indicates that Cex1 is not localized at the nuclear periphery as expected for an effector of nuclear tRNA channeling, but is observed on endosomal trans-Golgi network (TGN) positive structures. This localization relies on the vacuolar protein sorting receptor Vps10. Our data not only resolve the functional ambiguity regarding Cex1 homologues across species, but also point to the possibility to develop yeast-based models to study neurodegenerative disorders linked to the Human Cex1 homologue SCYL1.

Autophagy Modulators and Neuroinflammation

2020 ◽  
Vol 27 (6) ◽  
pp. 955-982 ◽  
Author(s):  
Kyoung Sang Cho ◽  
Jang Ho Lee ◽  
Jeiwon Cho ◽  
Guang-Ho Cha ◽  
Gyun Jee Song
Keyword(s):  
Neurodegenerative Disorders ◽  
Neurological Disorders ◽  
Mammalian Cells ◽  
Critical Role ◽  
Therapeutic Agents ◽  
Mechanisms Of Action ◽  
Scientific Interest ◽  
Therapeutic Tools ◽  
Underlying Mechanisms

Background: Neuroinflammation plays a critical role in the development and progression of various neurological disorders. Therefore, various studies have focused on the development of neuroinflammation inhibitors as potential therapeutic tools. Recently, the involvement of autophagy in the regulation of neuroinflammation has drawn substantial scientific interest, and a growing number of studies support the role of impaired autophagy in the pathogenesis of common neurodegenerative disorders. Objective: The purpose of this article is to review recent research on the role of autophagy in controlling neuroinflammation. We focus on studies employing both mammalian cells and animal models to evaluate the ability of different autophagic modulators to regulate neuroinflammation. Methods: We have mostly reviewed recent studies reporting anti-neuroinflammatory properties of autophagy. We also briefly discussed a few studies showing that autophagy modulators activate neuroinflammation in certain conditions. Results: Recent studies report neuroprotective as well as anti-neuroinflammatory effects of autophagic modulators. We discuss the possible underlying mechanisms of action of these drugs and their potential limitations as therapeutic agents against neurological disorders. Conclusion: Autophagy activators are promising compounds for the treatment of neurological disorders involving neuroinflammation.

scholarly journals Small GTPases of the Rab and Arf Families: Key Regulators of Intracellular Trafficking in Neurodegeneration

2021 ◽  
Vol 22 (9) ◽  
pp. 4425
Author(s):  
Alazne Arrazola Arrazola Sastre ◽  
Miriam Luque Luque Montoro ◽  
Hadriano M. Lacerda ◽  
Francisco Llavero ◽  
José L. Zugaza
Keyword(s):  
Membrane Trafficking ◽  
Neurodegenerative Disorders ◽  
Synaptic Vesicles ◽  
Intracellular Trafficking ◽  
Small Gtpases ◽  
Constant Flow ◽  
Parkinson’S Diseases ◽  
The Central Nervous System ◽  
Arf Gtpases

Small guanosine triphosphatases (GTPases) of the Rab and Arf families are key regulators of vesicle formation and membrane trafficking. Membrane transport plays an important role in the central nervous system. In this regard, neurons require a constant flow of membranes for the correct distribution of receptors, for the precise composition of proteins and organelles in dendrites and axons, for the continuous exocytosis/endocytosis of synaptic vesicles and for the elimination of dysfunctional proteins. Thus, it is not surprising that Rab and Arf GTPases have been associated with neurodegenerative diseases such as Alzheimer’s and Parkinson’s. Both pathologies share characteristics such as the presence of protein aggregates and/or the fragmentation of the Golgi apparatus, hallmarks that have been related to both Rab and Arf GTPases functions. Despite their relationship with neurodegenerative disorders, very few studies have focused on the role of these GTPases in the pathogenesis of neurodegeneration. In this review, we summarize their importance in the onset and progression of Alzheimer’s and Parkinson’s diseases, as well as their emergence as potential therapeutical targets for neurodegeneration.

scholarly journals The Putative Eukaryote-LikeO-GlcNAc Transferase of the Cyanobacterium Synechococcus elongatus PCC 7942 Hydrolyzes UDP-GlcNAc and Is Involved in Multiple Cellular Processes

2014 ◽  
Vol 197 (2) ◽  
pp. 354-361 ◽  
Author(s):  
Kerry A. Sokol ◽  
Neil E. Olszewski
Keyword(s):  
Deletion Mutant ◽  
Bacterial Species ◽  
Synechococcus Elongatus ◽  
Single Amino Acid ◽  
Content Type ◽  
Cellular Processes ◽  
Mutant Phenotypes ◽  
Glcnac Transferase ◽  
Pcc 7942 ◽  
Mutant Cells

The posttranslational addition of a single O-linked β-N-acetylglucosamine (O-GlcNAc) to serine or threonine residues regulates numerous metazoan cellular processes. The enzyme responsible for this modification,O-GlcNAc transferase (OGT), is conserved among a wide variety of organisms and is critical for the viability of many eukaryotes. Although OGTs with domain structures similar to those of eukaryotic OGTs are predicted for many bacterial species, the cellular roles of these OGTs are unknown. We have identified a putative OGT in the cyanobacteriumSynechococcus elongatusPCC 7942 that shows active-site homology and similar domain structure to eukaryotic OGTs. An OGT deletion mutant was created and found to exhibit several phenotypes. Without agitation, mutant cells aggregate and settle out of the medium. The mutant cells have higher free inorganic phosphate levels, wider thylakoid lumen, and differential accumulation of electron-dense inclusion bodies. These phenotypes are rescued by reintroduction of the wild-type OGT but are not fully rescued by OGTs with single amino acid substitutions corresponding to mutations that reduce eukaryotic OGT activity.S. elongatusOGT purified fromEscherichia colihydrolyzed the sugar donor, UDP-GlcNAc, while the mutant OGTs that did not fully rescue the deletion mutant phenotypes had reduced or no activity. These results suggest that bacterial eukaryote-like OGTs, like their eukaryotic counterparts, influence multiple processes.

scholarly journals Complex II subunit SDHD is critical for cell growth and metabolism, which can be partially restored with a synthetic ubiquinone analog

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Aloka B. Bandara ◽  
Joshua C. Drake ◽  
David A. Brown
Keyword(s):  
Mammalian Cells ◽  
Krebs Cycle ◽  
Atp Synthesis ◽  
Hek293 Cells ◽  
Knockout Mutant ◽  
Complex Ii ◽  
Growth Defects ◽  
Transport Chain ◽  
Mutant Cells

Abstract Background Succinate dehydrogenase (Complex II) plays a dual role in respiration by catalyzing the oxidation of succinate to fumarate in the mitochondrial Krebs cycle and transferring electrons from succinate to ubiquinone in the mitochondrial electron transport chain (ETC). Mutations in Complex II are associated with a number of pathologies. SDHD, one of the four subunits of Complex II, serves by anchoring the complex to the inner-membrane and transferring electrons from the complex to ubiquinone. Thus, modeling SDHD dysfunction could be a valuable tool for understanding its importance in metabolism and developing novel therapeutics, however no suitable models exist. Results Via CRISPR/Cas9, we mutated SDHD in HEK293 cells and investigated the in vitro role of SDHD in metabolism. Compared to the parent HEK293, the knockout mutant HEK293ΔSDHD produced significantly less number of cells in culture. The mutant cells predictably had suppressed Complex II-mediated mitochondrial respiration, but also Complex I-mediated respiration. SDHD mutation also adversely affected glycolytic capacity and ATP synthesis. Mutant cells were more apoptotic and susceptible to necrosis. Treatment with the mitochondrial therapeutic idebenone partially improved oxygen consumption and growth of mutant cells. Conclusions Overall, our results suggest that SDHD is vital for growth and metabolism of mammalian cells, and that respiratory and growth defects can be partially restored with treatment of a ubiquinone analog. This is the first report to use CRISPR/Cas9 approach to construct a knockout SDHD cell line and evaluate the efficacy of an established mitochondrial therapeutic candidate to improve bioenergetic capacity.

A novel mitochondrial m.14430A>G (MT-ND6, p.W82R) variant causes complex I deficiency and mitochondrial Leigh syndrome

2020 ◽  
Vol 58 (11) ◽  
pp. 1809-1817
Author(s):  
Miaomiao Du ◽  
Xiujuan Wei ◽  
Pu Xu ◽  
Anran Xie ◽  
Xiyue Zhou ◽  
...  
Keyword(s):  
Mitochondrial Respiration ◽  
Complex I ◽  
Clinical Symptoms ◽  
Lactate Production ◽  
Mitochondrial Diseases ◽  
Leigh Syndrome ◽  
Extracellular Lactate ◽  
Next Generation Sequencing Ngs ◽  
Mutant Cells ◽  
Generation Sequencing

AbstractObjectivesLeigh syndrome (LS) is one of the most common mitochondrial diseases and has variable clinical symptoms. However, the genetic variant spectrum of this disease is incomplete.MethodsNext-generation sequencing (NGS) was used to identify the m.14430A > G (p.W82R) variant in a patient with LS. The pathogenesis of this novel complex I (CI) variant was verified by determining the mitochondrial respiration, assembly of CI, ATP, MMP and lactate production, and cell growth rate in cybrids with and without this variant.ResultsA novel m.14430A > G (p.W82R) variant in the NADH dehydrogenase 6 (ND6) gene was identified in the patient; the mutant loads of m.14430A > G (p.W82R) in the patient were much higher than those in his mother. Although the transmitochondrial cybrid-based study showed that mitochondrial CI assembly remains unaffected in cells with the m.14430G variant, control cells had significantly higher endogenous and CI-dependent mitochondrial respiration than mutant cells. Accordingly, mutant cells had a lower ATP, MMP and higher extracellular lactate production than control cells. Notably, mutant cells had impaired growth in a galactose-containing medium when compared to wild-type cells.ConclusionsA novel m.14430A > G (p.W82R) variant in the ND6 gene was identified from a patient suspected to have LS, and this variant impaired mitochondrial respiration by decreasing the activity of mitochondrial CI.

scholarly journals Protein Glycosylation inAspergillus fumigatusIs Essential for Cell Wall Synthesis and Serves as a Promising Model of Multicellular Eukaryotic Development

2012 ◽  
Vol 2012 ◽  
pp. 1-21 ◽  
Author(s):  
Cheng Jin
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Wall ◽  
Posttranslational Modification ◽  
Mammalian Cells ◽  
Protein Glycosylation ◽  
Cell Wall Synthesis ◽  
Fungal Cell ◽  
Multiple Functions ◽  
Significant Attention

Glycosylation is a conserved posttranslational modification that is found in all eukaryotes, which helps generate proteins with multiple functions. Our knowledge of glycosylation mainly comes from the investigation of the yeastSaccharomyces cerevisiaeand mammalian cells. However, during the last decade, glycosylation in the human pathogenic moldAspergillus fumigatushas drawn significant attention. It has been revealed that glycosylation inA. fumigatusis crucial for its growth, cell wall synthesis, and development and that the process is more complicated than that found in the budding yeastS. cerevisiae. The present paper implies that the investigation of glycosylation inA. fumigatusis not only vital for elucidating the mechanism of fungal cell wall synthesis, which will benefit the design of new antifungal therapies, but also helps to understand the role of protein glycosylation in the development of multicellular eukaryotes. This paper describes the advances in functional analysis of protein glycosylation inA. fumigatus.

scholarly journals RCAN1 Regulates Mitochondrial Function and Increases Susceptibility to Oxidative Stress in Mammalian Cells

2014 ◽  
Vol 2014 ◽  
pp. 1-12 ◽  
Author(s):  
Heshan Peiris ◽  
Daphne Dubach ◽  
Claire F. Jessup ◽  
Petra Unterweger ◽  
Ravinarayan Raghupathi ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Mitochondrial Function ◽  
Neurodegenerative Disorders ◽  
Mammalian Cells ◽  
Cell Function ◽  
Cellular Energy ◽  
Mitochondrial Ros ◽  
Ros Accumulation ◽  
The Brain ◽  
Increased Susceptibility

Mitochondria are the primary site of cellular energy generation and reactive oxygen species (ROS) accumulation. Elevated ROS levels are detrimental to normal cell function and have been linked to the pathogenesis of neurodegenerative disorders such as Down's syndrome (DS) and Alzheimer’s disease (AD). RCAN1 is abundantly expressed in the brain and overexpressed in brain of DS and AD patients. Data from nonmammalian species indicates that increased RCAN1 expression results in altered mitochondrial function and that RCAN1 may itself regulate neuronal ROS production. In this study, we have utilized mice overexpressing RCAN1RCAN1oxand demonstrate an increased susceptibility of neurons from these mice to oxidative stress. Mitochondria from these mice are more numerous and smaller, indicative of mitochondrial dysfunction, and mitochondrial membrane potential is altered under conditions of oxidative stress. We also generated a PC12 cell line overexpressing RCAN1PC12RCAN1. Similar toRCAN1oxneurons,PC12RCAN1cells have an increased susceptibility to oxidative stress and produce more mitochondrial ROS. This study demonstrates that increasing RCAN1 expression alters mitochondrial function and increases the susceptibility of neurons to oxidative stress in mammalian cells. These findings further contribute to our understanding of RCAN1 and its potential role in the pathogenesis of neurodegenerative disorders such as AD and DS.

The kinetics of the B cyclin p56cdc13 and the phosphatase p80cdc25 during the cell cycle of the fission yeast Schizosaccharomyces pombe

1996 ◽  
Vol 109 (6) ◽  
pp. 1647-1653 ◽  
Author(s):  
J. Creanor ◽  
J.M. Mitchison
Keyword(s):  
Schizosaccharomyces Pombe ◽  
Mammalian Cells ◽  
Size Control ◽  
Base Line ◽  
Wild Type ◽  
Main Band ◽  
The Times ◽  
G1 Cells ◽  
Mutant Cells ◽  
Kinetics Of

The levels of the B cyclin p56cdc13 and the phosphatase p80cdc25 have been followed in selection-synchronised cultures of Schizosaccharomyces pombe wild-type and wee1 mutant cells. p56cdc13 has also been followed in induction-synchronised cells of the mutant cdc2-33. The main conclusions are: (1) cdc13 levels in wild-type cells start to rise from base line at about mid-G2, reach a peak before mitosis and then fall slowly through G1. Cells exit mitosis with appreciable levels of cdc13. (2) cdc13 levels in wee1 cells fall to zero in interphase. They also start to rise at the beginning of G2, which may be related to the absence of a mitotic size control. (3) cdc25 starts to rise later and reaches a peak after mitosis. This is not what would be expected from a simple mitotic inducer and suggests that cdc25 has an important function at the end of mitosis. (4) An upper (heavier) band of cdc25 peaks at the same time as the main band but rises and falls more rapidly. If this is a hyperphosphorylated form, its timing shows that it is most unlikely to function in the ways shown for such a form in eggs and mammalian cells. (5) Experiments with the mutant cdc10-129 and with hydroxyurea show that the initial signal to begin synthesis of cdc13 originates at Start. (6) In induction synchrony, where G2 spans across cell division, there is evidence that some events in one cycle cannot start in the previous one. (7) Revised timings are given for the times of mitosis in these cultures.

scholarly journals Isolation and functional expression of human COQ2, a gene encoding a polyprenyl transferase involved in the synthesis of CoQ

2004 ◽  
Vol 382 (2) ◽  
pp. 519-526 ◽  
Author(s):  
Margareta FORSGREN ◽  
Anneli ATTERSAND ◽  
Staffan LAKE ◽  
Jacob GRÜNLER ◽  
Ewa SWIEZEWSKA ◽  
...  
Keyword(s):  
Biosynthetic Pathway ◽  
Functional Expression ◽  
Human Muscle ◽  
Null Mutant ◽  
Human Homologue ◽  
Gene Encoding ◽  
Reading Frame ◽  
Human Enzyme ◽  
Liver Cdna Library ◽  
Mutant Cells

The COQ2 gene in Saccharomyces cerevisiae encodes a Coq2 (p-hydroxybenzoate:polyprenyl transferase), which is required in the biosynthetic pathway of CoQ (ubiquinone). This enzyme catalyses the prenylation of p-hydroxybenzoate with an all-trans polyprenyl group. We have isolated cDNA which we believe encodes the human homologue of COQ2 from a human muscle and liver cDNA library. The clone contained an open reading frame of length 1263 bp, which encodes a polypeptide that has sequence homology with the Coq2 homologues in yeast, bacteria and mammals. The human COQ2 gene, when expressed in yeast Coq2 null mutant cells, rescued the growth of this yeast strain in the absence of a non-fermentable carbon source and restored CoQ biosynthesis. However, the rate of CoQ biosynthesis in the rescued cells was lower when compared with that in cells rescued with the yeast COQ2 gene. CoQ formed when cells were incubated with labelled decaprenyl pyrophosphate and nonaprenyl pyrophosphate, showing that the human enzyme is active and that it participates in the biosynthesis of CoQ.

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