51
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Yamazaki R, Ishibashi T, Baba H, Yamaguchi Y. Expression of Unconventional Myosin VI in Oligodendrocytes. Neurochem Res 2017; 42:3372-3381. [PMID: 28828543 DOI: 10.1007/s11064-017-2377-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2017] [Revised: 08/01/2017] [Accepted: 08/07/2017] [Indexed: 12/01/2022]
Abstract
Myelin is a specialized multilamellar structure involved in various functions of the nervous system. Oligodendrocytes are responsible for myelin formation in the central nervous system. Motor proteins play important roles in differentiation and myelin formation of the oligodendrocyte lineage. Recently, we revealed that one of the unconventional myosins, myosin ID (Myo1d), is expressed in mature oligodendrocytes and is required for myelin-like membrane formation in vitro. Previously, Cahoy et al. (J Neurosci 28:264-278, 2008) reported that another unconventional myosin VI (Myo6) is upregulated in transcriptome data of differentiated oligodendrocytes. However, it is uncertain whether Myo6 protein is present in oligodendrocytes. In this study, to analyze expression of Myo6 in oligodendrocytes, we performed immunofluorescence analysis on brains of adult normal and cuprizone-induced demyelination mice. Myo6 expression was detected in mature oligodendrocytes and oligodendrocyte progenitor cells in the cerebellum and corpus callosum. To compare temporal expression patterns of myosin superfamily members in vitro, double immunostainings using anti-Myo6, myosin Va (Myo5a), or Myo1d with each stage-specific oligodendrocyte marker antibody were performed. In cultured oligodendrocytes, although Myo1d was found only in mature oligodendrocytes, Myo6 and Myo5a signals were detected in all stages of differentiation, from oligodendrocyte progenitor cells to mature oligodendrocytes. Additionally, similar to Myo5a, Myo6-positive signals were confined to the cell body and processes. These results showed that Myo6 is one of the unconventional myosins in oligodendrocyte lineage cells, which could play a role in clathrin-related endocytosis.
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Affiliation(s)
- Reiji Yamazaki
- Department of Molecular Neurobiology, Tokyo University of Pharmacy and Life Sciences, 1432-1 Horinouchi, Hachioji, Tokyo, 192-0392, Japan
| | - Tomoko Ishibashi
- Department of Molecular Neurobiology, Tokyo University of Pharmacy and Life Sciences, 1432-1 Horinouchi, Hachioji, Tokyo, 192-0392, Japan
| | - Hiroko Baba
- Department of Molecular Neurobiology, Tokyo University of Pharmacy and Life Sciences, 1432-1 Horinouchi, Hachioji, Tokyo, 192-0392, Japan
| | - Yoshihide Yamaguchi
- Department of Molecular Neurobiology, Tokyo University of Pharmacy and Life Sciences, 1432-1 Horinouchi, Hachioji, Tokyo, 192-0392, Japan.
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52
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How myosin organization of the actin cytoskeleton contributes to the cancer phenotype. Biochem Soc Trans 2017; 44:1026-34. [PMID: 27528748 DOI: 10.1042/bst20160034] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2016] [Indexed: 12/29/2022]
Abstract
The human genome contains 39 genes that encode myosin heavy chains, classified on the basis of their sequence similarity into 12 classes. Most cells express at least 12 different genes, from at least 8 different classes, which are typically composed of several class 1 genes, at least one class 2 gene and classes 5, 6, 9, 10, 18 and 19. Although the different myosin isoforms all have specific and non-overlapping roles in the cell, in combination they all contribute to the organization of the actin cytoskeleton, and the shape and phenotype of the cell. Over (or under) expression of these different myosin isoforms can have strong effects on actin organization, cell shape and contribute to the cancer phenotype as discussed in this review.
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53
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Shang G, Brautigam CA, Chen R, Lu D, Torres-Vázquez J, Zhang X. Structure analyses reveal a regulated oligomerization mechanism of the PlexinD1/GIPC/myosin VI complex. eLife 2017; 6. [PMID: 28537552 PMCID: PMC5461112 DOI: 10.7554/elife.27322] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Accepted: 05/23/2017] [Indexed: 12/22/2022] Open
Abstract
The GIPC family adaptor proteins mediate endocytosis by tethering cargo proteins to the myosin VI motor. The structural mechanisms for the GIPC/cargo and GIPC/myosin VI interactions remained unclear. PlexinD1, a transmembrane receptor that regulates neuronal and cardiovascular development, is a cargo of GIPCs. GIPC-mediated endocytic trafficking regulates PlexinD1 signaling. Here, we unravel the mechanisms of the interactions among PlexinD1, GIPCs and myosin VI by a series of crystal structures of these proteins in apo or bound states. GIPC1 forms a domain-swapped dimer in an autoinhibited conformation that hinders binding of both PlexinD1 and myosin VI. PlexinD1 binding to GIPC1 releases the autoinhibition, promoting its interaction with myosin VI. GIPCs and myosin VI interact through two distinct interfaces and form an open-ended alternating array. Our data support that this alternating array underlies the oligomerization of the GIPC/Myosin VI complexes in solution and cells. DOI:http://dx.doi.org/10.7554/eLife.27322.001
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Affiliation(s)
- Guijun Shang
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, United States
| | - Chad A Brautigam
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, United States.,Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, United States
| | - Rui Chen
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, United States
| | - Defen Lu
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, United States
| | - Jesús Torres-Vázquez
- Department of Cell Biology, Skirball Institute of Biomolecular Medicine, New York, United States
| | - Xuewu Zhang
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, United States.,Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, United States
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54
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Abstract
Myosin VI (MVI) is a versatile actin-based motor protein that has been implicated in a variety of different cellular processes, including endo- and exocytic vesicle trafficking, Golgi morphology, and actin structure stabilization. A role for MVI in crucial actin-based processes involved in sperm maturation was demonstrated in Drosophila. Because of the prominence and importance of actin structures in mammalian spermiogenesis, we investigated whether MVI was associated with actin-mediated maturation events in mammals. Both immunofluorescence and ultrastructural analyses using immunogold labeling showed that MVI was strongly linked with key structures involved in sperm development and maturation. During the early stage of spermiogenesis, MVI is associated with the Golgi and with coated and uncoated vesicles, which fuse to form the acrosome. Later, as the acrosome spreads to form a cap covering the sperm nucleus, MVI is localized to the acroplaxome, an actin-rich structure that anchors the acrosome to the nucleus. Finally, during the elongation/maturation phase, MVI is associated with the actin-rich structures involved in nuclear shaping: the acroplaxome, manchette, and Sertoli cell actin hoops. Since this is the first report of MVI expression and localization during mouse spermiogenesis and MVI partners in developing sperm have not yet been identified, we discuss some probable roles for MVI in this process. During early stages, MVI is hypothesized to play a role in Golgi morphology and function as well as in actin dynamics regulation important for attachment of developing acrosome to the nuclear envelope. Next, the protein might also play anchoring roles to help generate forces needed for spermatid head elongation. Moreover, association of MVI with actin that accumulates in the Sertoli cell ectoplasmic specialization and other actin structures in surrounding cells suggests additional MVI functions in spermatid movement across the seminiferous epithelium and in sperm release.
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55
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Markovinovic A, Cimbro R, Ljutic T, Kriz J, Rogelj B, Munitic I. Optineurin in amyotrophic lateral sclerosis: Multifunctional adaptor protein at the crossroads of different neuroprotective mechanisms. Prog Neurobiol 2017; 154:1-20. [PMID: 28456633 DOI: 10.1016/j.pneurobio.2017.04.005] [Citation(s) in RCA: 66] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2017] [Revised: 04/09/2017] [Accepted: 04/16/2017] [Indexed: 12/12/2022]
Abstract
When optineurin mutations showed up on the amyotrophic lateral sclerosis (ALS) landscape in 2010, they differed from most other ALS-causing genes. They seemed to act by loss- rather than gain-of-function, and it was unclear how a polyubiquitin-binding adaptor protein, which was proposed to regulate a variety of cellular functions including cell signaling and vesicle trafficking, could mediate neuroprotection. This review discusses the considerable progress that has been made since then. A large number of mutations in optineurin and optineurin-interacting proteins TANK-binding kinase (TBK1) and p62/SQSTM-1 have been found in the ALS patients, suggesting a common neuroprotective pathway. Moreover, functional studies of the ALS-causing optineurin mutations and the recently established optineurin ubiquitin-binding deficient and knockout mouse models helped identify three major mechanisms likely to mediate neuroprotection: regulation of autophagy, mitigation of (chronic) inflammatory signaling, and blockade of necroptosis. These three processes crosstalk, and require multiple levels of control, many of which can be mediated by optineurin. Based on the role of optineurin in multiple processes and the unexpected finding that targeted optineurin deletion in microglia and oligodendrocytes ultimately leads to the same phenotype of axonal degeneration despite different initial defects, we propose that the failure of the weakest link in the optineurin neuroprotective network is sufficient to disturb homeostasis and set-off the domino effect that could ultimately lead to neurodegeneration.
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Affiliation(s)
- Andrea Markovinovic
- Laboratory of Molecular Immunology, Department of Biotechnology, University of Rijeka, 51000 Rijeka, Croatia
| | - Raffaello Cimbro
- Division of Rheumatology, Johns Hopkins School of Medicine, Baltimore, MD 21224, USA
| | - Tereza Ljutic
- Laboratory of Molecular Immunology, Department of Biotechnology, University of Rijeka, 51000 Rijeka, Croatia
| | - Jasna Kriz
- Department of Psychiatry and Neuroscience, Faculty of Medicine, Research Centre of the Mental Health Institute of Quebec, Laval University, Quebec, Quebec G1J 2G3, Canada
| | - Boris Rogelj
- Department of Biotechnology, Jožef Stefan Institute, Faculty of Chemistry and Chemical Technology, University of Ljubljana, Biomedical Research Institute BRIS, SI-1000 Ljubljana, Slovenia
| | - Ivana Munitic
- Laboratory of Molecular Immunology, Department of Biotechnology, University of Rijeka, 51000 Rijeka, Croatia.
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56
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MYO6 is targeted by Salmonella virulence effectors to trigger PI3-kinase signaling and pathogen invasion into host cells. Proc Natl Acad Sci U S A 2017; 114:3915-3920. [PMID: 28348208 DOI: 10.1073/pnas.1616418114] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
To establish infections, Salmonella injects virulence effectors that hijack the host actin cytoskeleton and phosphoinositide signaling to drive pathogen invasion. How effectors reprogram the cytoskeleton network remains unclear. By reconstituting the activities of the Salmonella effector SopE, we recapitulated Rho GTPase-driven actin polymerization at model phospholipid membrane bilayers in cell-free extracts and identified the network of Rho-recruited cytoskeleton proteins. Knockdown of network components revealed a key role for myosin VI (MYO6) in Salmonella invasion. SopE triggered MYO6 localization to invasion foci, and SopE-mediated activation of PAK recruited MYO6 to actin-rich membranes. We show that the virulence effector SopB requires MYO6 to regulate the localization of PIP3 and PI(3)P phosphoinositides and Akt activation. SopE and SopB target MYO6 to coordinate phosphoinositide production at invasion foci, facilitating the recruitment of cytoskeleton adaptor proteins to mediate pathogen uptake.
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57
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Investigations of human myosin VI targeting using optogenetically controlled cargo loading. Proc Natl Acad Sci U S A 2017; 114:E1607-E1616. [PMID: 28193860 DOI: 10.1073/pnas.1614716114] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Myosins play countless critical roles in the cell, each requiring it to be activated at a specific location and time. To control myosin VI with this specificity, we created an optogenetic tool for activating myosin VI by fusing the light-sensitive Avena sativa phototropin1 LOV2 domain to a peptide from Dab2 (LOVDab), a myosin VI cargo protein. Our approach harnesses the native targeting and activation mechanism of myosin VI, allowing direct inferences on myosin VI function. LOVDab robustly recruits human full-length myosin VI to various organelles in vivo and hinders peroxisome motion in a light-controllable manner. LOVDab also activates myosin VI in an in vitro gliding filament assay. Our data suggest that protein and lipid cargoes cooperate to activate myosin VI, allowing myosin VI to integrate Ca2+, lipid, and protein cargo signals in the cell to deploy in a site-specific manner.
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58
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Filopodia formation and endosome clustering induced by mutant plus-end-directed myosin VI. Proc Natl Acad Sci U S A 2017; 114:1595-1600. [PMID: 28143933 DOI: 10.1073/pnas.1616941114] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Myosin VI (MYO6) is the only myosin known to move toward the minus end of actin filaments. It has roles in numerous cellular processes, including maintenance of stereocilia structure, endocytosis, and autophagosome maturation. However, the functional necessity of minus-end-directed movement along actin is unclear as the underlying architecture of the local actin network is often unknown. To address this question, we engineered a mutant of MYO6, MYO6+, which undergoes plus-end-directed movement while retaining physiological cargo interactions in the tail. Expression of this mutant motor in HeLa cells led to a dramatic reorganization of cortical actin filaments and the formation of actin-rich filopodia. MYO6 is present on peripheral adaptor protein, phosphotyrosine interacting with PH domain and leucine zipper 1 (APPL1) signaling endosomes and MYO6+ expression causes a dramatic relocalization and clustering of this endocytic compartment in the cell cortex. MYO6+ and its adaptor GAIP interacting protein, C terminus (GIPC) accumulate at the tips of these filopodia, while APPL1 endosomes accumulate at the base. A combination of MYO6+ mutagenesis and siRNA-mediated depletion of MYO6 binding partners demonstrates that motor activity and binding to endosomal membranes mediated by GIPC and PI(4,5)P2 are crucial for filopodia formation. A similar reorganization of actin is induced by a constitutive dimer of MYO6+, indicating that multimerization of MYO6 on endosomes through binding to GIPC is required for this cellular activity and regulation of actin network structure. This unique engineered MYO6+ offers insights into both filopodia formation and MYO6 motor function at endosomes and at the plasma membrane.
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59
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Waxse BJ, Sengupta P, Hesketh GG, Lippincott-Schwartz J, Buss F. Myosin VI facilitates connexin 43 gap junction accretion. J Cell Sci 2017; 130:827-840. [PMID: 28096472 PMCID: PMC5358335 DOI: 10.1242/jcs.199083] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2016] [Accepted: 01/04/2017] [Indexed: 12/19/2022] Open
Abstract
In this study, we demonstrate myosin VI enrichment at Cx43 (also known as GJA1)-containing gap junctions (GJs) in heart tissue, primary cardiomyocytes and cell culture models. In primary cardiac tissue and in fibroblasts from the myosin VI-null mouse as well as in tissue culture cells transfected with siRNA against myosin VI, we observe reduced GJ plaque size with a concomitant reduction in intercellular communication, as shown by fluorescence recovery after photobleaching (FRAP) and a new method of selective calcein administration. Analysis of the molecular role of myosin VI in Cx43 trafficking indicates that myosin VI is dispensable for the delivery of Cx43 to the cell surface and connexon movement in the plasma membrane. Furthermore, we cannot corroborate clathrin or Dab2 localization at gap junctions and we do not observe a function for the myosin-VI-Dab2 complex in clathrin-dependent endocytosis of annular gap junctions. Instead, we found that myosin VI was localized at the edge of Cx43 plaques by using total internal reflection fluorescence (TIRF) microscopy and use FRAP to identify a plaque accretion defect as the primary manifestation of myosin VI loss in Cx43 homeostasis. A fuller understanding of this derangement may explain the cardiomyopathy or gliosis associated with the loss of myosin VI.
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Affiliation(s)
- Bennett J Waxse
- Cell Biology and Metabolism Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, Maryland 20892, USA.,Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 2XY, UK
| | - Prabuddha Sengupta
- Cell Biology and Metabolism Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, Maryland 20892, USA
| | - Geoffrey G Hesketh
- Mount Sinai Hospital, Lunenfeld-Tanenbaum Research Institute, Toronto, Ontario M5G 1X5, Canada
| | - Jennifer Lippincott-Schwartz
- Cell Biology and Metabolism Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, Maryland 20892, USA
| | - Folma Buss
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 2XY, UK
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60
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Masters TA, Kendrick-Jones J, Buss F. Myosins: Domain Organisation, Motor Properties, Physiological Roles and Cellular Functions. Handb Exp Pharmacol 2017; 235:77-122. [PMID: 27757761 DOI: 10.1007/164_2016_29] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Myosins are cytoskeletal motor proteins that use energy derived from ATP hydrolysis to generate force and movement along actin filaments. Humans express 38 myosin genes belonging to 12 classes that participate in a diverse range of crucial activities, including muscle contraction, intracellular trafficking, cell division, motility, actin cytoskeletal organisation and cell signalling. Myosin malfunction has been implicated a variety of disorders including deafness, hypertrophic cardiomyopathy, Usher syndrome, Griscelli syndrome and cancer. In this chapter, we will first discuss the key structural and kinetic features that are conserved across the myosin family. Thereafter, we summarise for each member in turn its unique functional and structural adaptations, cellular roles and associated pathologies. Finally, we address the broad therapeutic potential for pharmacological interventions that target myosin family members.
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Affiliation(s)
- Thomas A Masters
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, CB2 0XY, UK.
| | | | - Folma Buss
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, CB2 0XY, UK
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61
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Abstract
The cause of Crohn’s disease (CD) has posed a conundrum for at least a century. A large body of work coupled with recent technological advances in genome research have at last started to provide some of the answers. Initially this review seeks to explain and to differentiate between bowel inflammation in the primary immunodeficiencies that generally lead to very early onset diffuse bowel inflammation in humans and in animal models, and the real syndrome of CD. In the latter, a trigger, almost certainly enteric infection by one of a multitude of organisms, allows the faeces access to the tissues, at which stage the response of individuals predisposed to CD is abnormal. Direct investigation of patients’ inflammatory response together with genome-wide association studies (GWAS) and DNA sequencing indicate that in CD the failure of acute inflammation and the clearance of bacteria from the tissues, and from within cells, is defective. The retained faecal products result in the characteristic chronic granulomatous inflammation and adaptive immune response. In this review I will examine the contemporary evidence that has led to this understanding, and look for explanations for the recent dramatic increase in the incidence of this disease.
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62
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Abstract
The cause of Crohn's disease (CD) has posed a conundrum for at least a century. A large body of work coupled with recent technological advances in genome research have at last started to provide some of the answers. Initially this review seeks to explain and to differentiate between bowel inflammation in the primary immunodeficiencies that generally lead to very early onset diffuse bowel inflammation in humans and in animal models, and the real syndrome of CD. In the latter, a trigger, almost certainly enteric infection by one of a multitude of organisms, allows the faeces access to the tissues, at which stage the response of individuals predisposed to CD is abnormal. Direct investigation of patients' inflammatory response together with genome-wide association studies (GWAS) and DNA sequencing indicate that in CD the failure of acute inflammation and the clearance of bacteria from the tissues, and from within cells, is defective. The retained faecal products result in the characteristic chronic granulomatous inflammation and adaptive immune response. In this review I will examine the contemporary evidence that has led to this understanding, and look for explanations for the recent dramatic increase in the incidence of this disease.
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63
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Xie X, Li F, Wang Y, Wang Y, Lin Z, Cheng X, Liu J, Chen C, Pan L. Molecular basis of ubiquitin recognition by the autophagy receptor CALCOCO2. Autophagy 2016; 11:1775-89. [PMID: 26506893 DOI: 10.1080/15548627.2015.1082025] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The autophagy receptor CALCOCO2/NDP52 functions as a bridging adaptor and plays an essential role in the selective autophagic degradation of invading pathogens by specifically recognizing ubiquitin-coated intracellular pathogens and subsequently targeting them to the autophagic machinery; thereby it is required for innate immune defense against a range of infectious pathogens in mammals. However, the mechanistic basis underlying CALCOCO2-mediated specific recognition of ubiqutinated pathogens is still unknown. Here, using biochemical and structural analyses, we demonstrated that the cargo-binding region of CALCOCO2 contains a dynamic unconventional zinc finger as well as a C2H2-type zinc-finger, and only the C2H2-type zinc finger specifically recognizes mono-ubiquitin or poly-ubiquitin chains. In addition to elucidating the specific ubiquitin recognition mechanism of CALCOCO2, the structure of the CALCOCO2 C2H2-type zinc finger in complex with mono-ubiquitin also uncovers a unique zinc finger-binding mode for ubiquitin. Our findings provide mechanistic insight into how CALCOCO2 targets ubiquitin-decorated pathogens for autophagic degradations.
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Affiliation(s)
- Xingqiao Xie
- a State Key Laboratory of Bioorganic and Natural Products Chemistry
| | - Faxiang Li
- a State Key Laboratory of Bioorganic and Natural Products Chemistry.,b Interdisciplinary Research Center on Biology and Chemistry
| | - Yuanyuan Wang
- d Unit of Pathogenic Fungal Infection and Host Immunity; Institut Pasteur of Shanghai; Chinese Academy of Science ; Shanghai , China
| | - Yingli Wang
- a State Key Laboratory of Bioorganic and Natural Products Chemistry
| | - Zhijie Lin
- e Division of Life Science, State Key Laboratory of Molecular Neuroscience; Hong Kong University of Science and Technology ; Kowloon , Hong Kong , China
| | - Xiaofang Cheng
- a State Key Laboratory of Bioorganic and Natural Products Chemistry.,b Interdisciplinary Research Center on Biology and Chemistry
| | - Jianping Liu
- a State Key Laboratory of Bioorganic and Natural Products Chemistry
| | - Changbin Chen
- d Unit of Pathogenic Fungal Infection and Host Immunity; Institut Pasteur of Shanghai; Chinese Academy of Science ; Shanghai , China
| | - Lifeng Pan
- a State Key Laboratory of Bioorganic and Natural Products Chemistry.,c Collaborative Innovation Center of Chemistry for Life Sciences; Shanghai Institute of Organic Chemistry; Chinese Academy of Sciences ; Shanghai , China
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64
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Fifita JA, Williams KL, Sundaramoorthy V, Mccann EP, Nicholson GA, Atkin JD, Blair IP. A novel amyotrophic lateral sclerosis mutation in OPTN induces ER stress and Golgi fragmentation in vitro. Amyotroph Lateral Scler Frontotemporal Degener 2016; 18:126-133. [DOI: 10.1080/21678421.2016.1218517] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Jennifer A. Fifita
- Faculty of Medicine and Health Sciences, Macquarie University, Sydney, New South Wales, Australia,
| | - Kelly L. Williams
- Faculty of Medicine and Health Sciences, Macquarie University, Sydney, New South Wales, Australia,
| | - Vinod Sundaramoorthy
- Faculty of Medicine and Health Sciences, Macquarie University, Sydney, New South Wales, Australia,
| | - Emily P. Mccann
- Faculty of Medicine and Health Sciences, Macquarie University, Sydney, New South Wales, Australia,
| | - Garth A. Nicholson
- Faculty of Medicine and Health Sciences, Macquarie University, Sydney, New South Wales, Australia,
- Northcott Neuroscience Laboratory, ANZAC Research Institute, Sydney, New South Wales, Australia,
- Sydney Medical School, University of Sydney, Sydney, New South Wales, Australia,
- Molecular Medicine Laboratory, Concord Hospital, Concord, New South Wales, Australia, and
| | - Julie D. Atkin
- Faculty of Medicine and Health Sciences, Macquarie University, Sydney, New South Wales, Australia,
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Victoria, Australia
| | - Ian P. Blair
- Faculty of Medicine and Health Sciences, Macquarie University, Sydney, New South Wales, Australia,
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65
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Loss of cargo binding in the human myosin VI deafness mutant (R1166X) leads to increased actin filament binding. Biochem J 2016; 473:3307-19. [PMID: 27474411 PMCID: PMC5074368 DOI: 10.1042/bcj20160571] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Accepted: 07/28/2016] [Indexed: 12/31/2022]
Abstract
Mutations in myosin VI have been associated with autosomal-recessive (DFNB37) and autosomal-dominant (DFNA22) deafness in humans. Here, we characterise an myosin VI nonsense mutation (R1166X) that was identified in a family with hereditary hearing loss in Pakistan. This mutation leads to the deletion of the C-terminal 120 amino acids of the myosin VI cargo-binding domain, which includes the WWY-binding motif for the adaptor proteins LMTK2, Tom1 as well as Dab2. Interestingly, compromising myosin VI vesicle-binding ability by expressing myosin VI with the R1166X mutation or with single point mutations in the adaptor-binding sites leads to increased F-actin binding of this myosin in vitro and in vivo As our results highlight the importance of cargo attachment for regulating actin binding to the motor domain, we perform a detailed characterisation of adaptor protein binding and identify single amino acids within myosin VI required for binding to cargo adaptors. We not only show that the adaptor proteins can directly interact with the cargo-binding tail of myosin VI, but our in vitro studies also suggest that multiple adaptor proteins can bind simultaneously to non-overlapping sites in the myosin VI tail. In conclusion, our characterisation of the human myosin VI deafness mutant (R1166X) suggests that defects in cargo binding may leave myosin VI in a primed/activated state with an increased actin-binding ability.
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66
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TLR and TNF-R1 activation of the MKK3/MKK6-p38α axis in macrophages is mediated by TPL-2 kinase. Biochem J 2016; 473:2845-61. [PMID: 27402796 PMCID: PMC5095906 DOI: 10.1042/bcj20160502] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Accepted: 07/11/2016] [Indexed: 01/08/2023]
Abstract
Previous studies suggested that Toll-like receptor (TLR) stimulation of the p38α MAP kinase (MAPK) is mediated by transforming growth factor-β-activated kinase 1 (TAK1) activation of MAPK kinases, MKK3, MKK4 and MKK6. We used quantitative mass spectrometry to monitor tumour progression locus 2 (TPL-2)-dependent protein phosphorylation following TLR4 stimulation with lipopolysaccharide, comparing macrophages from wild-type mice and Map3k8(D270A/D270A) mice expressing catalytically inactive TPL-2 (MAP3K8). In addition to the established TPL-2 substrates MKK1/2, TPL-2 kinase activity was required to phosphorylate the activation loops of MKK3/6, but not of MKK4. MKK3/6 activation required IκB kinase (IKK) phosphorylation of the TPL-2 binding partner nuclear factor κ-light-chain-enhancer of activated B cells (NF-κB1) p105, similar to MKK1/2 activation. Tumour necrosis factor (TNF) stimulation of MKK3/6 phosphorylation was similarly dependent on TPL-2 catalytic activity and IKK phosphorylation of NF-κB1 p105. Owing to redundancy of MKK3/6 with MKK4, Map3k8(D270A) mutation only fractionally decreased lipopolysaccharide activation of p38α. TNF activation of p38α, which is mediated predominantly via MKK3/6, was substantially reduced. TPL-2 catalytic activity was also required for MKK3/6 and p38α activation following macrophage stimulation with Mycobacterium tuberculosis and Listeria monocytogenes Our experiments demonstrate that the IKK/NF-κB1 p105/TPL-2 signalling pathway, downstream of TAK1, regulates MKK3/6 and p38α activation in macrophages in inflammation.
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67
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Panarella A, Bexiga MG, Galea G, O’ Neill ED, Salvati A, Dawson KA, Simpson JC. A systematic High-Content Screening microscopy approach reveals key roles for Rab33b, OATL1 and Myo6 in nanoparticle trafficking in HeLa cells. Sci Rep 2016; 6:28865. [PMID: 27374232 PMCID: PMC4931513 DOI: 10.1038/srep28865] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2016] [Accepted: 06/06/2016] [Indexed: 12/24/2022] Open
Abstract
Synthetic nanoparticles are promising tools for imaging and drug delivery; however the molecular details of cellular internalization and trafficking await full characterization. Current knowledge suggests that following endocytosis most nanoparticles pass from endosomes to lysosomes. In order to design effective drug delivery strategies that can use the endocytic pathway, or by-pass lysosomal accumulation, a comprehensive understanding of nanoparticle uptake and trafficking mechanisms is therefore fundamental. Here we describe and apply an RNA interference-based high-content screening microscopy strategy to assess the intracellular trafficking of fluorescently-labeled polystyrene nanoparticles in HeLa cells. We screened a total of 408 genes involved in cytoskeleton and membrane function, revealing roles for myosin VI, Rab33b and OATL1 in this process. This work provides the first systematic large-scale quantitative assessment of the proteins responsible for nanoparticle trafficking in cells, paving the way for subsequent genome-wide studies.
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Affiliation(s)
- Angela Panarella
- School of Biology and Environmental Science, University College Dublin, Belfield, Dublin 4, Ireland
- Conway Institute for Biomolecular and Biomedical Research, University College Dublin, Belfield, Dublin 4, Ireland
| | - Mariana G. Bexiga
- School of Biology and Environmental Science, University College Dublin, Belfield, Dublin 4, Ireland
- Conway Institute for Biomolecular and Biomedical Research, University College Dublin, Belfield, Dublin 4, Ireland
| | - George Galea
- School of Biology and Environmental Science, University College Dublin, Belfield, Dublin 4, Ireland
- Conway Institute for Biomolecular and Biomedical Research, University College Dublin, Belfield, Dublin 4, Ireland
| | - Elaine D. O’ Neill
- School of Biology and Environmental Science, University College Dublin, Belfield, Dublin 4, Ireland
- Conway Institute for Biomolecular and Biomedical Research, University College Dublin, Belfield, Dublin 4, Ireland
| | - Anna Salvati
- Centre for BioNano Interactions, School of Chemistry and Chemical Biology, University College Dublin, Belfield, Dublin 4, Ireland
| | - Kenneth A. Dawson
- Centre for BioNano Interactions, School of Chemistry and Chemical Biology, University College Dublin, Belfield, Dublin 4, Ireland
| | - Jeremy C. Simpson
- School of Biology and Environmental Science, University College Dublin, Belfield, Dublin 4, Ireland
- Conway Institute for Biomolecular and Biomedical Research, University College Dublin, Belfield, Dublin 4, Ireland
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68
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Kruppa AJ, Kendrick-Jones J, Buss F. Myosins, Actin and Autophagy. Traffic 2016; 17:878-90. [PMID: 27146966 PMCID: PMC4957615 DOI: 10.1111/tra.12410] [Citation(s) in RCA: 67] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2016] [Revised: 05/02/2016] [Accepted: 05/02/2016] [Indexed: 12/20/2022]
Abstract
Myosin motor proteins working together with the actin cytoskeleton drive a wide range of cellular processes. In this review, we focus on their roles in autophagy – the pathway the cell uses to ensure homeostasis by targeting pathogens, misfolded proteins and damaged organelles for degradation. The actin cytoskeleton regulated by a host of nucleating, anchoring and stabilizing proteins provides the filament network for the delivery of essential membrane vesicles from different cellular compartments to the autophagosome. Actin networks have also been implicated in structurally supporting the expanding phagophore, moving autophagosomes and enabling efficient fusion with the lysosome. Only a few myosins have so far been shown to play a role in autophagy. Non‐muscle myosin IIA functions in the early stages delivering membrane for the initial formation of the autophagosome, whereas myosin IC and myosin VI are involved in the final stages providing specific membranes for autophagosome maturation and its fusion with the lysosome.
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Affiliation(s)
- Antonina J Kruppa
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge Biomedical Campus, Wellcome Trust/MRC Building, Hills Road, Cambridge, CB2 0XY, UK
| | - John Kendrick-Jones
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge, CB2 0QH, UK
| | - Folma Buss
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge Biomedical Campus, Wellcome Trust/MRC Building, Hills Road, Cambridge, CB2 0XY, UK
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69
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Epigenetic Regulation of Adaptive NK Cell Diversification. Trends Immunol 2016; 37:451-461. [PMID: 27160662 DOI: 10.1016/j.it.2016.04.006] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Revised: 04/11/2016] [Accepted: 04/14/2016] [Indexed: 01/08/2023]
Abstract
Natural killer (NK) cells were previously considered to represent short-lived, innate lymphocytes. However, mouse models have revealed expansion and persistence of differentiated NK cell subsets in response to cytomegalovirus (CMV) infection, paralleling antigen-specific T cell differentiation. Congruently, analyses of humans have uncovered CMV-associated NK cell subsets characterized by epigenetic diversification processes that lead to altered target cell specificities and functional capacities. Here, focusing on responses to viruses, we review similarities and differences between mouse and human adaptive NK cells, identifying molecular analogies that may be key to transcriptional reprogramming and functional alterations. We discuss possible molecular mechanisms underlying epigenetic diversification and hypothesize that processes driving epigenetic diversification may represent a more widespread mechanism for fine-tuning and optimization of cellular immunity.
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70
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Heaslip AT, Nelson SR, Warshaw DM. Dense granule trafficking in Toxoplasma gondii requires a unique class 27 myosin and actin filaments. Mol Biol Cell 2016; 27:2080-9. [PMID: 27146112 PMCID: PMC4927281 DOI: 10.1091/mbc.e15-12-0824] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Accepted: 04/26/2016] [Indexed: 11/18/2022] Open
Abstract
The survival of Toxoplasma gondii within its host cell requires protein release from vesicles, called dense granules (DGs). Through imaging of the motions of DGs in live intracellular parasites, it is shown that DG transport is dependent on F-actin and a class 27 myosin, TgMyoF, thus uncovering new critical roles for these essential proteins in the parasite’s lytic cycle. The survival of Toxoplasma gondii within its host cell requires protein release from secretory vesicles, called dense granules, to maintain the parasite’s intracellular replicative niche. Despite the importance of DGs, nothing is known about the mechanisms underlying their transport. In higher eukaryotes, secretory vesicles are transported to the plasma membrane by molecular motors moving on their respective cytoskeletal tracks (i.e., microtubules and actin). Because the organization of these cytoskeletal structures differs substantially in T. gondii, the molecular motor dependence of DG trafficking is far from certain. By imaging the motions of green fluorescent protein–tagged DGs in intracellular parasites with high temporal and spatial resolution, we show through a combination of molecular genetics and chemical perturbations that directed DG transport is independent of microtubules and presumably their kinesin/dynein motors. However, directed DG transport is dependent on filamentous actin and a unique class 27 myosin, TgMyoF, which has structural similarity to myosin V, the prototypical cargo transporter. Actomyosin DG transport was unexpected, since filamentous parasite actin has yet to be visualized in vivo due in part to the prevailing model that parasite actin forms short, unstable filaments. Thus our data uncover new critical roles for these essential proteins in the lytic cycle of this devastating pathogen.
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Affiliation(s)
- Aoife T Heaslip
- Department of Molecular Physiology and Biophysics, University of Vermont, Burlington, VT 05405
| | - Shane R Nelson
- Department of Molecular Physiology and Biophysics, University of Vermont, Burlington, VT 05405
| | - David M Warshaw
- Department of Molecular Physiology and Biophysics, University of Vermont, Burlington, VT 05405
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71
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Hegan PS, Lanahan AA, Simons M, Mooseker MS. Myosin VI and cardiomyopathy: Left ventricular hypertrophy, fibrosis, and both cardiac and pulmonary vascular endothelial cell defects in the Snell's waltzer mouse. Cytoskeleton (Hoboken) 2016; 72:373-87. [PMID: 26265212 DOI: 10.1002/cm.21236] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2015] [Revised: 07/30/2015] [Accepted: 08/07/2015] [Indexed: 12/17/2022]
Abstract
In mice and humans, loss of myosin VI (Myo6) function results in deafness, and certain Myo6 mutations also result in cardiomyopathies in humans. The current studies have utilized the Snell's waltzer (sv) mouse (a functional null mutation for Myo6) to determine if this mouse also exhibits cardiac defects and thus used to determine the cellular and molecular basis for Myo6-associated heart disease. Myo6 is expressed in mouse heart where it is predominantly expressed in vascular endothelial cells (VECs) based on co-localization with the VEC cell marker CD31. Sv/sv heart mass is significantly greater than that of sv/+ littermates, a result of left ventricle hypertrophy. The left ventricle of the sv/sv exhibits extensive fibrosis, both interstitial and perivascular, based on histologic staining, and immunolocalization of several markers for fibrosis including fibronectin, collagen IV, and the fibroblast marker vimentin. Myo6 is also expressed in lung VECs but not in VECs of intestine, kidney, or liver. Sv/sv lungs exhibit increased periaveolar fibrosis and enlarged air sacs. Electron microscopy of sv/sv cardiac and lung VECs revealed abnormal ultrastructure, including luminal protrusions and increased numbers of cytoplasmic vesicles. Previous studies have shown that loss of function of either Myo6 or its adaptor binding partner synectin/GIPC results in impaired arterial development due to defects in VEGF signaling. However, examination of synectin/GIPC-/- heart revealed no fibrosis or significantly altered VEC ultrastructure, suggesting that the cardiac and lung defects observed in the sv/sv mouse are not due to Myo6 function in arterial development.
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Affiliation(s)
- Peter S Hegan
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, Connecticut
| | - Anthony A Lanahan
- Department of Internal Medicine, Yale School of Medicine, New Haven, Connecticut
| | - Michael Simons
- Department of Internal Medicine, Yale School of Medicine, New Haven, Connecticut.,Department of Cell Biology, Yale School of Medicine, New Haven, Connecticut
| | - Mark S Mooseker
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, Connecticut.,Department of Cell Biology, Yale School of Medicine, New Haven, Connecticut.,Department of Pathology, Yale School of Medicine, New Haven, Connecticut
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72
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Immunolocalization of Tom1 in relation to protein degradation systems in Alzheimer's disease. J Neurol Sci 2016; 365:101-7. [PMID: 27206884 DOI: 10.1016/j.jns.2016.03.035] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2016] [Revised: 03/18/2016] [Accepted: 03/21/2016] [Indexed: 12/11/2022]
Abstract
Alzheimer's disease (AD) is an age-related neurodegenerative disorder. Its pathological hallmarks are senile plaques (SPs), which contain extracellular deposits of amyloid β (Aβ) protein fibrils and dystrophic neurites (DNs), and neurofibrillary tangles (NFTs) containing hyperphosphorylated tau. Impairment of protein-degradation systems, including the ubiquitin-proteasome and the autophagy-lysosome systems, has been proposed as one of the causes of the accumulation of these aberrant proteins in AD brains. Tom1 (target of Myb1) was originally identified by the induction of its expression by the v-Myb oncogene and is a part of two major protein-degradation systems. The present study was conducted by immunohistochemical and immunofluorescent stainings to show that Tom1 was localized in DNs, perisomatic granules (PSGs), and NFTs in AD brains. Moreover, in DNs, Tom1 colocalized with ubiquitin, lysosomal proteins, and Tom1-related proteins (Tollip and myosin VI), which act in both protein-degradation systems via Tom1. These results indicate that Tom1 plays important roles in protein-degradation systems in AD pathogenesis.
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73
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Heissler SM, Sellers JR. Kinetic Adaptations of Myosins for Their Diverse Cellular Functions. Traffic 2016; 17:839-59. [PMID: 26929436 DOI: 10.1111/tra.12388] [Citation(s) in RCA: 65] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2016] [Revised: 02/25/2016] [Accepted: 02/25/2016] [Indexed: 12/18/2022]
Abstract
Members of the myosin superfamily are involved in all aspects of eukaryotic life. Their function ranges from the transport of organelles and cargos to the generation of membrane tension, and the contraction of muscle. The diversity of physiological functions is remarkable, given that all enzymatically active myosins follow a conserved mechanoenzymatic cycle in which the hydrolysis of ATP to ADP and inorganic phosphate is coupled to either actin-based transport or tethering of actin to defined cellular compartments. Kinetic capacities and limitations of a myosin are determined by the extent to which actin can accelerate the hydrolysis of ATP and the release of the hydrolysis products and are indispensably linked to its physiological tasks. This review focuses on kinetic competencies that - together with structural adaptations - result in myosins with unique mechanoenzymatic properties targeted to their diverse cellular functions.
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Affiliation(s)
- Sarah M Heissler
- Laboratory of Molecular Physiology, National Heart, Lung, and Blood Institute, National Institutes of Health, 50 South Drive, B50/3523, Bethesda, MD 20892-8015, USA
| | - James R Sellers
- Laboratory of Molecular Physiology, National Heart, Lung, and Blood Institute, National Institutes of Health, 50 South Drive, B50/3523, Bethesda, MD 20892-8015, USA
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74
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Sobczak M, Chumak V, Pomorski P, Wojtera E, Majewski Ł, Nowak J, Yamauchi J, Rędowicz MJ. Interaction of myosin VI and its binding partner DOCK7 plays an important role in NGF-stimulated protrusion formation in PC12 cells. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2016; 1863:1589-600. [PMID: 27018747 DOI: 10.1016/j.bbamcr.2016.03.020] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2015] [Revised: 03/05/2016] [Accepted: 03/22/2016] [Indexed: 10/22/2022]
Abstract
DOCK7 (dedicator of cytokinesis 7) is a guanidine nucleotide exchange factor (GEF) for Rac1 GTPase that is involved in neuronal polarity and axon generation as well in Schwann cell differentiation and myelination. Recently, we identified DOCK7 as the binding partner of unconventional myosin VI (MVI) in neuronal-lineage PC12 cells and postulated that this interaction could be important in vivo [Majewski et al. (2012) Biochem Cell Biol., 90:565-574]. Herein, we found that MVI-DOCK7 interaction takes also place in other cell lines and demonstrated that MVI cargo domain via its RRL motif binds to DOCK7 C-terminal M2 and DHR2 domains. In MVI knockdown cells, lower Rac1 activity and a decrease of DOCK7 phosphorylation on Tyr1118 were observed, indicating that MVI could contribute to DOCK7 activity. MVI and DOCK7 co-localization was maintained during NGF-stimulated PC12 cell differentiation and observed also in the outgrowths. Also, during differentiation an increase in phosphorylation of DOCK7 as well as of its downstream effector JNK kinase was detected. Interestingly, overexpression of GFP-tagged MVI cargo domain (GFP-GT) impaired protrusion formation indicating that full length protein is important for this process. Moreover, a transient increase in Rac activity observed at 5min of NGF-stimulated differentiation of PC12 cells (overexpressing either GFP or GFP-MVI) was not detected in cells overexpressing the cargo domain. These data indicate that MVI-DOCK7 interaction could have functional implications in the protrusion outgrowth, and full length MVI seems to be important for delivery and maintenance of DOCK7 along the protrusions, and exerting its GEF activity.
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Affiliation(s)
- Magdalena Sobczak
- Laboratory of Molecular Basis of Cell Motility, Department of Biochemistry, Nencki Institute of Experimental Biology, 3 Pasteur St., 02-093 Warsaw, Poland
| | - Vira Chumak
- Laboratory of Molecular Basis of Cell Motility, Department of Biochemistry, Nencki Institute of Experimental Biology, 3 Pasteur St., 02-093 Warsaw, Poland; Laboratory of Regulation of Cell Proliferation and Apoptosis, Institute of Cell Biology, National Academy of Sciences of Ukraine, 14-16 Drahomanov St., 79005 Lviv, Ukraine
| | - Paweł Pomorski
- Laboratory of Molecular Basis of Cell Motility, Department of Biochemistry, Nencki Institute of Experimental Biology, 3 Pasteur St., 02-093 Warsaw, Poland
| | - Emilia Wojtera
- Laboratory of Molecular Basis of Cell Motility, Department of Biochemistry, Nencki Institute of Experimental Biology, 3 Pasteur St., 02-093 Warsaw, Poland
| | - Łukasz Majewski
- Laboratory of Molecular Basis of Cell Motility, Department of Biochemistry, Nencki Institute of Experimental Biology, 3 Pasteur St., 02-093 Warsaw, Poland
| | - Jolanta Nowak
- Laboratory of Molecular Basis of Cell Motility, Department of Biochemistry, Nencki Institute of Experimental Biology, 3 Pasteur St., 02-093 Warsaw, Poland
| | - Junji Yamauchi
- Department of Pharmacology, National Research Institute for Child Health and Development, Setagaya, Tokyo, Japan; Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Bunkyo, Tokyo, Japan
| | - Maria Jolanta Rędowicz
- Laboratory of Molecular Basis of Cell Motility, Department of Biochemistry, Nencki Institute of Experimental Biology, 3 Pasteur St., 02-093 Warsaw, Poland.
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75
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Christinat Y, Pawłowski R, Krek W. jSplice: a high-performance method for accurate prediction of alternative splicing events and its application to large-scale renal cancer transcriptome data. Bioinformatics 2016; 32:2111-9. [PMID: 27153587 DOI: 10.1093/bioinformatics/btw145] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2015] [Accepted: 03/11/2016] [Indexed: 01/01/2023] Open
Abstract
MOTIVATION Alternative splicing represents a prime mechanism of post-transcriptional gene regulation whose misregulation is associated with a broad range of human diseases. Despite the vast availability of transcriptome data from different cell types and diseases, bioinformatics-based surveys of alternative splicing patterns remain a major challenge due to limited availability of analytical tools that combine high accuracy and rapidity. RESULTS We describe here a novel junction-centric method, jSplice, that enables de novo extraction of alternative splicing events from RNA-sequencing data with high accuracy, reliability and speed. Application to clear cell renal carcinoma (ccRCC) cell lines and 65 ccRCC patients revealed experimentally validatable alternative splicing changes and signatures able to prognosticate ccRCC outcome. In the aggregate, our results propose jSplice as a key analytic tool for the derivation of cell context-dependent alternative splicing patterns from large-scale RNA-sequencing datasets. AVAILABILITY AND IMPLEMENTATION jSplice is a standalone Python application freely available at http://www.mhs.biol.ethz.ch/research/krek/jsplice CONTACT wilhelm.krek@biol.ethz.ch SUPPLEMENTARY INFORMATION Supplementary data are available at Bioinformatics online.
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Affiliation(s)
- Yann Christinat
- Institute of Molecular Health Sciences, ETH Zurich, Zurich 8093, Switzerland
| | - Rafał Pawłowski
- Institute of Molecular Health Sciences, ETH Zurich, Zurich 8093, Switzerland
| | - Wilhelm Krek
- Institute of Molecular Health Sciences, ETH Zurich, Zurich 8093, Switzerland
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76
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Li J, Lu Q, Zhang M. Structural Basis of Cargo Recognition by Unconventional Myosins in Cellular Trafficking. Traffic 2016; 17:822-38. [PMID: 26842936 DOI: 10.1111/tra.12383] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Revised: 01/29/2016] [Accepted: 01/29/2016] [Indexed: 01/17/2023]
Abstract
Unconventional myosins are a superfamily of actin-based molecular motors playing diverse roles including cellular trafficking, mechanical supports, force sensing and transmission, etc. The variable neck and tail domains of unconventional myosins function to bind to specific cargoes including proteins and lipid vesicles and thus are largely responsible for the diverse cellular functions of myosins in vivo. In addition, the tail regions, together with their cognate cargoes, can regulate activities of the motor heads. This review outlines the advances made in recent years on cargo recognition and cargo binding-induced regulation of the activity of several unconventional myosins including myosin-I, V, VI and X in cellular trafficking. We approach this topic by describing a series of high-resolution structures of the neck and tail domains of these unconventional myosins either alone or in complex with their specific cargoes, and by discussing potential implications of these structural studies on cellular trafficking of these myosin motors.
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Affiliation(s)
- Jianchao Li
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Qing Lu
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Mingjie Zhang
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China.,Center of Systems Biology and Human Health, School of Science and Institute for Advanced Study, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
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77
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He F, Wollscheid HP, Nowicka U, Biancospino M, Valentini E, Ehlinger A, Acconcia F, Magistrati E, Polo S, Walters KJ. Myosin VI Contains a Compact Structural Motif that Binds to Ubiquitin Chains. Cell Rep 2016; 14:2683-94. [PMID: 26971995 DOI: 10.1016/j.celrep.2016.01.079] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2015] [Revised: 11/24/2015] [Accepted: 01/27/2016] [Indexed: 12/13/2022] Open
Abstract
Myosin VI is critical for cargo trafficking and sorting during early endocytosis and autophagosome maturation, and abnormalities in these processes are linked to cancers, neurodegeneration, deafness, and hypertropic cardiomyopathy. We identify a structured domain in myosin VI, myosin VI ubiquitin-binding domain (MyUb), that binds to ubiquitin chains, especially those linked via K63, K11, and K29. Herein, we solve the solution structure of MyUb and MyUb:K63-linked diubiquitin. MyUb folds as a compact helix-turn-helix-like motif and nestles between the ubiquitins of K63-linked diubiquitin, interacting with distinct surfaces of each. A nine-amino-acid extension at the C-terminal helix (Helix2) of MyUb is required for myosin VI interaction with endocytic and autophagic adaptors. Structure-guided mutations revealed that a functional MyUb is necessary for optineurin interaction. In addition, we found that an isoform-specific helix restricts MyUb binding to ubiquitin chains. This work provides fundamental insights into myosin VI interaction with ubiquitinated cargo and functional adaptors.
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Affiliation(s)
- Fahu He
- Protein Processing Section, Structural Biophysics Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702, USA
| | - Hans-Peter Wollscheid
- IFOM, Fondazione Istituto FIRC di Oncologia Molecolare, Via Adamello 16, 20139 Milano, Italy
| | - Urszula Nowicka
- Protein Processing Section, Structural Biophysics Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702, USA
| | - Matteo Biancospino
- IFOM, Fondazione Istituto FIRC di Oncologia Molecolare, Via Adamello 16, 20139 Milano, Italy
| | - Eleonora Valentini
- IFOM, Fondazione Istituto FIRC di Oncologia Molecolare, Via Adamello 16, 20139 Milano, Italy
| | - Aaron Ehlinger
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
| | - Filippo Acconcia
- IFOM, Fondazione Istituto FIRC di Oncologia Molecolare, Via Adamello 16, 20139 Milano, Italy
| | - Elisa Magistrati
- IFOM, Fondazione Istituto FIRC di Oncologia Molecolare, Via Adamello 16, 20139 Milano, Italy
| | - Simona Polo
- IFOM, Fondazione Istituto FIRC di Oncologia Molecolare, Via Adamello 16, 20139 Milano, Italy; DIPO, Dipartimento di Oncologia ed Emato-oncologia, Università degli Studi di Milano, Via di Rudinì 8, 20122 Milan, Italy.
| | - Kylie J Walters
- Protein Processing Section, Structural Biophysics Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702, USA.
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78
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Wollscheid HP, Biancospino M, He F, Magistrati E, Molteni E, Lupia M, Soffientini P, Rottner K, Cavallaro U, Pozzoli U, Mapelli M, Walters KJ, Polo S. Diverse functions of myosin VI elucidated by an isoform-specific α-helix domain. Nat Struct Mol Biol 2016; 23:300-308. [PMID: 26950368 PMCID: PMC4964928 DOI: 10.1038/nsmb.3187] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2015] [Accepted: 02/09/2016] [Indexed: 01/01/2023]
Abstract
Myosin VI functions in endocytosis and cell motility. Alternative splicing of myosin VI mRNA generates two distinct isoform types, myosin VIshort and myosin VIlong, which differ in the C-terminal region. Their physiological and pathological role remains unknown. Here we identified an isoform-specific regulatory helix, named α2-linker that defines specific conformations and hence determines the target selectivity of human myosin VI. The presence of the α2-linker structurally defines a novel clathrin-binding domain that is unique to myosin VIlong and masks the known RRL interaction motif. This finding is relevant to ovarian cancer, where alternative myosin VI splicing is aberrantly regulated, and exon skipping dictates cell addiction to myosin VIshort for tumor cell migration. The RRL interactor optineurin contributes to this process by selectively binding myosin VIshort. Thus the α2-linker acts like a molecular switch that assigns myosin VI to distinct endocytic (myosin VIlong) or migratory (myosin VIshort) functional roles.
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Affiliation(s)
| | - Matteo Biancospino
- Fondazione Istituto FIRC di Oncologia Molecolare (IFOM), Milan 20139, Italy
| | - Fahu He
- Center for Cancer Research, National Cancer Institute, Frederick, MD 21702, USA
| | - Elisa Magistrati
- Fondazione Istituto FIRC di Oncologia Molecolare (IFOM), Milan 20139, Italy
| | - Erika Molteni
- Computational Biology, Scientific Institute IRCCS E.MEDEA, Bosisio Parini 23842, Italy
| | - Michela Lupia
- Molecular Medicine Program, European Institute of Oncology, Milan 20141, Italy
| | - Paolo Soffientini
- Fondazione Istituto FIRC di Oncologia Molecolare (IFOM), Milan 20139, Italy
| | - Klemens Rottner
- Helmholtz Centre for Infection Research, 38124 Braunschweig, Germany.,Braunschweig University of Technology, 38106 Braunschweig, Germany
| | - Ugo Cavallaro
- Molecular Medicine Program, European Institute of Oncology, Milan 20141, Italy
| | - Uberto Pozzoli
- Computational Biology, Scientific Institute IRCCS E.MEDEA, Bosisio Parini 23842, Italy
| | - Marina Mapelli
- Department of Experimental Oncology, European Institute of Oncology, Milan 20139, Italy
| | - Kylie J Walters
- Center for Cancer Research, National Cancer Institute, Frederick, MD 21702, USA
| | - Simona Polo
- Fondazione Istituto FIRC di Oncologia Molecolare (IFOM), Milan 20139, Italy.,Dipartimento di oncologia ed emato-oncologia (DIPO), Universita' degli Studi di Milano, Milan 20122, Italy
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79
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80
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Tumbarello DA, Manna PT, Allen M, Bycroft M, Arden SD, Kendrick-Jones J, Buss F. The Autophagy Receptor TAX1BP1 and the Molecular Motor Myosin VI Are Required for Clearance of Salmonella Typhimurium by Autophagy. PLoS Pathog 2015; 11:e1005174. [PMID: 26451915 PMCID: PMC4599966 DOI: 10.1371/journal.ppat.1005174] [Citation(s) in RCA: 151] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2015] [Accepted: 08/28/2015] [Indexed: 01/12/2023] Open
Abstract
Autophagy plays a key role during Salmonella infection, by eliminating these pathogens following escape into the cytosol. In this process, selective autophagy receptors, including the myosin VI adaptor proteins optineurin and NDP52, have been shown to recognize cytosolic pathogens. Here, we demonstrate that myosin VI and TAX1BP1 are recruited to ubiquitylated Salmonella and play a key role in xenophagy. The absence of TAX1BP1 causes an accumulation of ubiquitin-positive Salmonella, whereas loss of myosin VI leads to an increase in ubiquitylated and LC3-positive bacteria. Our structural studies demonstrate that the ubiquitin-binding site of TAX1BP1 overlaps with the myosin VI binding site and point mutations in the TAX1BP1 zinc finger domains that affect ubiquitin binding also ablate binding to myosin VI. This mutually exclusive binding and the association of TAX1BP1 with LC3 on the outer limiting membrane of autophagosomes may suggest a molecular mechanism for recruitment of this motor to autophagosomes. The predominant role of TAX1BP1, a paralogue of NDP52, in xenophagy is supported by our evolutionary analysis, which demonstrates that functionally intact NDP52 is missing in Xenopus and mice, whereas TAX1BP1 is expressed in all vertebrates analysed. In summary, this work highlights the importance of TAX1BP1 as a novel autophagy receptor in myosin VI-mediated xenophagy. Our study identifies essential new machinery for the autophagy-dependent clearance of Salmonella typhimurium and suggests modulation of myosin VI motor activity as a potential therapeutic target in cellular immunity.
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Affiliation(s)
- David A. Tumbarello
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom
- * E-mail: (DAT); (FB)
| | - Paul T. Manna
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom
| | - Mark Allen
- MRC Laboratory of Molecular Biology, Cambridge, United Kingdom
| | - Mark Bycroft
- MRC Laboratory of Molecular Biology, Cambridge, United Kingdom
| | - Susan D. Arden
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom
| | | | - Folma Buss
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom
- * E-mail: (DAT); (FB)
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81
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Knipper M, Panford-Walsh R, Singer W, Rüttiger L, Zimmermann U. Specific synaptopathies diversify brain responses and hearing disorders: you lose the gain from early life. Cell Tissue Res 2015; 361:77-93. [PMID: 25843689 PMCID: PMC4487345 DOI: 10.1007/s00441-015-2168-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2015] [Accepted: 03/05/2015] [Indexed: 01/08/2023]
Abstract
Before hearing onset, inner hair cell (IHC) maturation proceeds under the influence of spontaneous Ca(2+) action potentials (APs). The temporal signature of the IHC Ca(2+) AP is modified through an efferent cholinergic feedback from the medial olivocochlear bundle (MOC) and drives the IHC pre- and post-synapse phenotype towards low spontaneous (spike) rate (SR), high-threshold characteristics. With sensory experience, the IHC pre- and post-synapse phenotype matures towards the instruction of low-SR, high-threshold and of high-SR, low-threshold auditory fiber characteristics. Corticosteroid feedback together with local brain-derived nerve growth factor (BDNF) and catecholaminergic neurotransmitters (dopamine) might be essential for this developmental step. In this review, we address the question of whether the control of low-SR and high-SR fiber characteristics is linked to various degrees of vulnerability of auditory fibers in the mature system. In particular, we examine several IHC synaptopathies in the context of various hearing disorders and exemplified shortfalls before and after hearing onset.
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Affiliation(s)
- Marlies Knipper
- Department of Otolaryngology, Head and Neck Surgery, Tübingen Hearing Research Center (THRC), Molecular Physiology of Hearing, University of Tübingen, Elfriede-Aulhorn-Straße 5, 72076 Tübingen, Germany
| | | | - Wibke Singer
- Department of Otolaryngology, Head and Neck Surgery, Tübingen Hearing Research Center (THRC), Molecular Physiology of Hearing, University of Tübingen, Elfriede-Aulhorn-Straße 5, 72076 Tübingen, Germany
| | - Lukas Rüttiger
- Department of Otolaryngology, Head and Neck Surgery, Tübingen Hearing Research Center (THRC), Molecular Physiology of Hearing, University of Tübingen, Elfriede-Aulhorn-Straße 5, 72076 Tübingen, Germany
| | - Ulrike Zimmermann
- Department of Otolaryngology, Head and Neck Surgery, Tübingen Hearing Research Center (THRC), Molecular Physiology of Hearing, University of Tübingen, Elfriede-Aulhorn-Straße 5, 72076 Tübingen, Germany
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82
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Deletion of myosin VI causes slow retinal optic neuropathy and age-related macular degeneration (AMD)-relevant retinal phenotype. Cell Mol Life Sci 2015; 72:3953-69. [PMID: 25939269 PMCID: PMC4575690 DOI: 10.1007/s00018-015-1913-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2014] [Revised: 04/20/2015] [Accepted: 04/23/2015] [Indexed: 11/16/2022]
Abstract
The unconventional myosin VI, a member of the actin-based motor protein family of myosins, is expressed in the retina. Its deletion was previously shown to reduce amplitudes of the a- and b-waves of the electroretinogram. Analyzing wild-type and myosin VI-deficient Snell’s Waltzer mice in more detail, the expression pattern of myosin VI in retinal pigment epithelium, outer limiting membrane, and outer plexiform layer could be linked with differential progressing ocular deficits. These encompassed reduced a-waves and b-waves and disturbed oscillatory potentials in the electroretinogram, photoreceptor cell death, retinal microglia infiltration, and formation of basal laminar deposits. A phenotype comprising features of glaucoma (neurodegeneration) and age-related macular degeneration could thus be uncovered that suggests dysfunction of myosin VI and its variable cargo adaptor proteins for membrane sorting and autophagy, as possible candidate mediators for both disease forms.
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83
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Karolczak J, Weis S, Ehler E, Kierdaszuk B, Berdyński M, Zekanowski C, Kamińska AM, Rędowicz MJ. Myosin VI localization and expression in striated muscle pathology. Anat Rec (Hoboken) 2015; 297:1706-13. [PMID: 25125183 DOI: 10.1002/ar.22967] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2013] [Accepted: 02/04/2014] [Indexed: 12/11/2022]
Abstract
Myosin VI (MVI) is a unique unconventional myosin translocating, unlike other myosins, towards the minus end of actin filaments. It is involved in numerous cellular processes such as endocytosis, intracellular trafficking, cell migration, and transcription. In mammalian skeletal muscles it localizes mainly to sarcoplasmic reticulum and is also present within the muscle nuclei and at the neuromuscular junction (Karolczak et al. Histochem Cell Biol 2013; 23:219-228). We have also shown that in denervated rat hindlimb muscle the MVI expression level is significantly increased and its localization is changed, indicating an important role of MVI in striated muscle pathology. Here, we addressed this problem by examining the distribution and expression levels of myosin VI in biopsies of skeletal muscles from patients with different myopathies. We found that, particularly in myopathies associated with fiber atrophy, the amount of MVI was enhanced and its localization in affected fibers was changed. Also, since a mutation within the human MVI gene was shown to be associated with cardiomyopathy, we assessed MVI localization and expression level in cardiac muscle using wild type and MLP(-/-) mice, a dilated cardiomyopathy model. No significant difference in MVI expression level was observed for both types of animals. MVI was found at intercalated discs and also at the sarcoplasmic reticulum. In the knockout mice, it was also present in ring-like structures surrounding the nuclei. The data indicate that in striated muscle MVI could be engaged in sarcoplasmic reticulum maintenance and/or functioning, vesicular transport, signal transmission and possibly in gene transcription.
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Affiliation(s)
- Justyna Karolczak
- Department of Biochemistry, Laboratory of Molecular Basis of Cell Motility, Nencki Institute of Experimental Biology, Warsaw, Poland
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84
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Involvement of unconventional myosin VI in myoblast function and myotube formation. Histochem Cell Biol 2015; 144:21-38. [PMID: 25896210 PMCID: PMC4469105 DOI: 10.1007/s00418-015-1322-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/07/2015] [Indexed: 01/01/2023]
Abstract
The important role of unconventional myosin VI (MVI) in skeletal and cardiac muscle has been recently postulated (Karolczak et al. in Histochem Cell Biol 139:873-885, 2013). Here, we addressed for the first time a role for this unique myosin motor in myogenic cells as well as during their differentiation into myotubes. During myoblast differentiation, the isoform expression pattern of MVI and its subcellular localization underwent changes. In undifferentiated myoblasts, MVI-stained puncti were seen throughout the cytoplasm and were in close proximity to actin filaments, Golgi apparatus, vinculin-, and talin-rich focal adhesion as well as endoplasmic reticulum. Colocalization of MVI with endoplasmic reticulum was enhanced during myotube formation, and differentiation-dependent association was also seen in sarcoplasmic reticulum of neonatal rat cardiomyocytes (NRCs). Moreover, we observed enrichment of MVI in myotube regions containing acetylcholine receptor-rich clusters, suggesting its involvement in the organization of the muscle postsynaptic machinery. Overexpression of the H246R MVI mutant (associated with hypertrophic cardiomyopathy) in myoblasts and NRCs caused the formation of abnormally large intracellular vesicles. MVI knockdown caused changes in myoblast morphology and inhibition of their migration. On the subcellular level, MVI-depleted myoblasts exhibited aberrations in the organization of actin cytoskeleton and adhesive structures as well as in integrity of Golgi apparatus and endoplasmic reticulum. Also, MVI depletion or overexpression of H246R mutant caused the formation of significantly wider or aberrant myotubes, respectively, indicative of involvement of MVI in myoblast differentiation. The presented results suggest an important role for MVI in myogenic cells and possibly in myoblast differentiation.
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85
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A Kinase Anchoring Protein 9 Is a Novel Myosin VI Binding Partner That Links Myosin VI with the PKA Pathway in Myogenic Cells. BIOMED RESEARCH INTERNATIONAL 2015; 2015:816019. [PMID: 25961040 PMCID: PMC4415471 DOI: 10.1155/2015/816019] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/20/2014] [Revised: 11/05/2014] [Accepted: 11/12/2014] [Indexed: 12/13/2022]
Abstract
Myosin VI (MVI) is a unique motor protein moving towards the minus end of actin filaments unlike other known myosins. Its important role has recently been postulated for striated muscle and myogenic cells. Since MVI functions through interactions of C-terminal globular tail (GT) domain with tissue specific partners, we performed a search for MVI partners in myoblasts and myotubes using affinity chromatography with GST-tagged MVI-GT domain as a bait. A kinase anchoring protein 9 (AKAP9), a regulator of PKA activity, was identified by means of mass spectrometry as a possible MVI interacting partner both in undifferentiated and differentiating myoblasts and in myotubes. Coimmunoprecipitation and proximity ligation assay confirmed that both proteins could interact. MVI and AKAP9 colocalized at Rab5 containing early endosomes. Similarly to MVI, the amount of AKAP9 decreased during myoblast differentiation. However, in MVI-depleted cells, both cAMP and PKA levels were increased and a change in the MVI motor-dependent AKAP9 distribution was observed. Moreover, we found that PKA phosphorylated MVI-GT domain, thus implying functional relevance of MVI-AKAP9 interaction. We postulate that this novel interaction linking MVI with the PKA pathway could be important for targeting AKAP9-PKA complex within cells and/or providing PKA to phosphorylate MVI tail domain.
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86
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Sundaramoorthy V, Walker AK, Tan V, Fifita JA, Mccann EP, Williams KL, Blair IP, Guillemin GJ, Farg MA, Atkin JD. Defects in optineurin- and myosin VI-mediated cellular trafficking in amyotrophic lateral sclerosis. Hum Mol Genet 2015; 24:3830-46. [DOI: 10.1093/hmg/ddv126] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2015] [Accepted: 04/07/2015] [Indexed: 12/12/2022] Open
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87
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Mitofusin 2-deficiency suppresses cell proliferation through disturbance of autophagy. PLoS One 2015; 10:e0121328. [PMID: 25781899 PMCID: PMC4363693 DOI: 10.1371/journal.pone.0121328] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2014] [Accepted: 01/30/2015] [Indexed: 12/20/2022] Open
Abstract
Mitofusin2 (Mfn2), a mitochondrial outer membrane protein serving primarily as a mitochondrial fusion protein, has multiple functions in regulating cell biological processes. Defects of Mfn2 were found in diabetes, obesity, and neurodegenerative diseases. In the present study, we found that knockdown of Mfn2 by shRNA led to impaired autophagic degradation, inhibited mitochondrial oxygen consumption rate and cell glycolysis, reduced ATP production, and suppressed cell proliferation. Inhibition of autophagic degradation mimicked Mfn2-deficiency mediated cell proliferation suppression, while enhancement of autophagosome maturation restored the suppressed cell proliferation by Mfn2-deficiency. Thus, our findings revealed the role of Mfn2 in regulating cell proliferation and mitochondrial metabolism, and shed new light on understanding the mechanisms of Mfn2 deficiency related diseases.
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88
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Myosin VI deafness mutation prevents the initiation of processive runs on actin. Proc Natl Acad Sci U S A 2015; 112:E1201-9. [PMID: 25751888 DOI: 10.1073/pnas.1420989112] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Mutations in the reverse-direction myosin, myosin VI, are associated with deafness in humans and mice. A myosin VI deafness mutation, D179Y, which is in the transducer of the motor, uncoupled the release of the ATP hydrolysis product, inorganic phosphate (Pi), from dependency on actin binding and destroyed the ability of single dimeric molecules to move processively on actin filaments. We observed that processive movement is rescued if ATP is added to the mutant dimer following binding of both heads to actin in the absence of ATP, demonstrating that the mutation selectively destroys the initiation of processive runs at physiological ATP levels. A drug (omecamtiv) that accelerates the actin-activated activity of cardiac myosin was able to rescue processivity of the D179Y mutant dimers at physiological ATP concentrations by slowing the actin-independent release of Pi. Thus, it may be possible to create myosin VI-specific drugs that rescue the function of deafness-causing mutations.
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89
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Mukherjea M, Ali MY, Kikuti C, Safer D, Yang Z, Sirkia H, Ropars V, Houdusse A, Warshaw DM, Sweeney HL. Myosin VI must dimerize and deploy its unusual lever arm in order to perform its cellular roles. Cell Rep 2014; 8:1522-32. [PMID: 25159143 DOI: 10.1016/j.celrep.2014.07.041] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2014] [Revised: 06/13/2014] [Accepted: 07/22/2014] [Indexed: 12/21/2022] Open
Abstract
It is unclear whether the reverse-direction myosin (myosin VI) functions as a monomer or dimer in cells and how it generates large movements on actin. We deleted a stable, single-α-helix (SAH) domain that has been proposed to function as part of a lever arm to amplify movements without impact on in vitro movement or in vivo functions. A myosin VI construct that used this SAH domain as part of its lever arm was able to take large steps in vitro but did not rescue in vivo functions. It was necessary for myosin VI to internally dimerize, triggering unfolding of a three-helix bundle and calmodulin binding in order to step normally in vitro and rescue endocytosis and Golgi morphology in myosin VI-null fibroblasts. A model for myosin VI emerges in which cargo binding triggers dimerization and unfolds the three-helix bundle to create a lever arm essential for in vivo functions.
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Affiliation(s)
- Monalisa Mukherjea
- Department of Physiology, University of Pennsylvania Perelman School of Medicine, 415 Curie Boulevard, 700 CRB, Philadelphia, PA 19104-6085, USA
| | - M Yusuf Ali
- Department of Molecular Physiology and Biophysics, University of Vermont, Burlington, VT 05405, USA
| | - Carlos Kikuti
- Structural Motility, Centre de Recherche, Institut Curie, 75248 Paris, France; CNRS, UMR144, 26 rue d'Ulm, 75248 Paris Cedex 05, France
| | - Daniel Safer
- Department of Physiology, University of Pennsylvania Perelman School of Medicine, 415 Curie Boulevard, 700 CRB, Philadelphia, PA 19104-6085, USA
| | - Zhaohui Yang
- Department of Physiology, University of Pennsylvania Perelman School of Medicine, 415 Curie Boulevard, 700 CRB, Philadelphia, PA 19104-6085, USA
| | - Helena Sirkia
- Structural Motility, Centre de Recherche, Institut Curie, 75248 Paris, France; CNRS, UMR144, 26 rue d'Ulm, 75248 Paris Cedex 05, France
| | - Virginie Ropars
- Structural Motility, Centre de Recherche, Institut Curie, 75248 Paris, France; CNRS, UMR144, 26 rue d'Ulm, 75248 Paris Cedex 05, France
| | - Anne Houdusse
- Structural Motility, Centre de Recherche, Institut Curie, 75248 Paris, France; CNRS, UMR144, 26 rue d'Ulm, 75248 Paris Cedex 05, France
| | - David M Warshaw
- Department of Molecular Physiology and Biophysics, University of Vermont, Burlington, VT 05405, USA
| | - H Lee Sweeney
- Department of Physiology, University of Pennsylvania Perelman School of Medicine, 415 Curie Boulevard, 700 CRB, Philadelphia, PA 19104-6085, USA.
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90
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Chen T, Hubbard A, Murtazina R, Price J, Yang J, Cha B, Sarker R, Donowitz M. Myosin VI mediates the movement of NHE3 down the microvillus in intestinal epithelial cells. J Cell Sci 2014; 127:3535-45. [PMID: 24928903 PMCID: PMC4132392 DOI: 10.1242/jcs.149930] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2014] [Accepted: 05/13/2014] [Indexed: 12/27/2022] Open
Abstract
The intestinal brush border Na(+)/H(+) exchanger NHE3 is tightly regulated through changes in its endocytosis and exocytosis. Myosin VI, a minus-end-directed actin motor, has been implicated in endocytosis at the inter-microvillar cleft and during vesicle remodeling in the terminal web. Here, we asked whether myosin VI also regulates NHE3 movement down the microvillus. The basal NHE3 activity and its surface amount, determined by fluorometry of the ratiometric pH indicator BCECF and biotinylation assays, respectively, were increased in myosin-VI-knockdown (KD) Caco-2/Bbe cells. Carbachol (CCH) and forskolin (FSK) stimulated NHE3 endocytosis in control but not in myosin VI KD cells. Importantly, immunoelectron microscopy results showed that NHE3 was preferentially localized in the basal half of control microvilli but in the distal half in myosin VI KD cells. Treatment with dynasore duplicated some aspects of myosin VI KD: it increased basal surface NHE3 activity and prevented FSK-induced NHE3 endocytosis. However, NHE3 had an intermediate distribution along the microvillus (between that in myosin VI KD and untreated cells) in dynasore-treated cells. We conclude that myosin VI is required for basal and stimulated endocytosis of NHE3 in intestinal cells, and suggest that myosin VI also moves NHE3 down the microvillus.
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Affiliation(s)
- Tiane Chen
- Department of Medicine, Division of Gastroenterology and Hepatology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Ann Hubbard
- Department of Medicine, Division of Gastroenterology and Hepatology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Rakhilya Murtazina
- Department of Medicine, Division of Gastroenterology and Hepatology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Jennifer Price
- Department of Medicine, Division of Gastroenterology and Hepatology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA Department of Gastroenterology, University of California, School of Medicine, San Francisco, CA 94143, USA
| | - Jianbo Yang
- Department of Medicine, Division of Gastroenterology and Hepatology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Boyoung Cha
- Department of Medicine, Division of Gastroenterology and Hepatology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Rafiquel Sarker
- Department of Medicine, Division of Gastroenterology and Hepatology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Mark Donowitz
- Department of Medicine, Division of Gastroenterology and Hepatology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA Departments of Medicine and Physiology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
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91
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Zhang X, Simons M. Receptor tyrosine kinases endocytosis in endothelium: biology and signaling. Arterioscler Thromb Vasc Biol 2014; 34:1831-7. [PMID: 24925972 DOI: 10.1161/atvbaha.114.303217] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Receptor tyrosine kinases are involved in regulation of key processes in endothelial biology, including proliferation, migration, and angiogenesis. It is now generally accepted that receptor tyrosine kinase signaling occurs intracellularly and on the plasma membrane, although many important details remain to be worked out. Endocytosis and subsequent intracellular trafficking spatiotemporally regulate receptor tyrosine kinase signaling, whereas signaling endosomes provide a platform for the compartmentalization of signaling events. This review summarizes recent advances in our understanding of endothelial receptor tyrosine kinase endocytosis and signaling using vascular endothelial growth factor receptor-2 as a paradigm.
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Affiliation(s)
- Xi Zhang
- From the Department of Cell Biology, and Yale Cardiovascular Research Center, Section of Cardiovascular Medicine, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT
| | - Michael Simons
- From the Department of Cell Biology, and Yale Cardiovascular Research Center, Section of Cardiovascular Medicine, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT.
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92
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Turturro S, Shen X, Shyam R, Yue BY, Ying H. Effects of mutations and deletions in the human optineurin gene. SPRINGERPLUS 2014; 3:99. [PMID: 24683533 PMCID: PMC3967732 DOI: 10.1186/2193-1801-3-99] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/15/2013] [Accepted: 02/13/2014] [Indexed: 01/14/2023]
Abstract
Optineurin is a gene associated with normal tension glaucoma (NTG) and amyotrophic lateral sclerosis (ALS). Foci formation and functional consequences including Golgi fragmentation, impairment of vesicle trafficking and apoptosis were observed previously upon overexpression and/or mutation of optineurin. In the current study, a total of 15 GFP tagged constructs that included NTG (E50K and 2 bp-AG insertion), ALS (exon 5 deletion, R96L, Q398X, and E478G) and non-disease (L157A and D474N) associated mutants and a series of deletion fragments were cloned into mammalian expression vectors and transfected into RGC5 and/or Neuro2A cells to evaluate whether their expression confer the optineurin phenotypes. The cells were monitored for foci formation and stained by immunofluorescence with anti-GM130 to analyze the Golgi integrity. Transferrin uptake experiments were performed to evaluate the protein trafficking process and apoptosis was assessed with the active caspase 3/7 detection kit. We demonstrated that cells expressing E50K and R96L optineurin exhibited all of the optineurin phenotypes. Q398X mutant did not induce foci formation, but triggered Golgi fragmentation, impairment of transferrin uptake and increase in apoptosis. The 2 bp-AG insertion mutant had a nuclear localization, compromised the transferrin uptake and strongly induced apoptosis. The foci formation, which might not predict the rest of the phenotypes, appeared to require both the leucine zipper and ubiquitin binding domains of the optineurin sequence. Interactions of optineurin with proteins including Rab8, myosin VI, huntingtin and transferrin receptor might directly determine whether the Golgi and protein trafficking phenotypes would be manifested. Examination of mutants and deletion fragments located at various sites of optineurin gene provide clues as to what regions of the gene may play a critical role in the development of pathologic consequences.
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Affiliation(s)
- Sanja Turturro
- Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, College of Medicine, 1855 W Taylor Street, Chicago, IL 60612 USA
| | - Xiang Shen
- Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, College of Medicine, 1855 W Taylor Street, Chicago, IL 60612 USA
| | - Rajalekshmy Shyam
- Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, College of Medicine, 1855 W Taylor Street, Chicago, IL 60612 USA
| | - Beatrice Yjt Yue
- Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, College of Medicine, 1855 W Taylor Street, Chicago, IL 60612 USA
| | - Hongyu Ying
- Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, College of Medicine, 1855 W Taylor Street, Chicago, IL 60612 USA
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93
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Waite AJ, Bäumer D, East S, Neal J, Morris HR, Ansorge O, Blake DJ. Reduced C9orf72 protein levels in frontal cortex of amyotrophic lateral sclerosis and frontotemporal degeneration brain with the C9ORF72 hexanucleotide repeat expansion. Neurobiol Aging 2014; 35:1779.e5-1779.e13. [PMID: 24559645 PMCID: PMC3988882 DOI: 10.1016/j.neurobiolaging.2014.01.016] [Citation(s) in RCA: 201] [Impact Index Per Article: 20.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2013] [Revised: 12/09/2013] [Accepted: 01/12/2014] [Indexed: 12/13/2022]
Abstract
An intronic G4C2 hexanucleotide repeat expansion in C9ORF72 is a major cause of amyotrophic lateral sclerosis and frontotemporal lobar degeneration. Several mechanisms including RNA toxicity, repeat-associated non-AUG translation mediated dipeptide protein aggregates, and haploinsufficiency of C9orf72 have been implicated in the molecular pathogenesis of this disorder. The aims of this study were to compare the use of two different Southern blot probes for detection of repeat expansions in an amyotrophic lateral sclerosis and frontotemporal lobar degeneration pathological cohort and to determine the levels of C9orf72 transcript variants and protein isoforms in patients versus control subjects. Our Southern blot studies identified smaller repeat expansions (250–1800 bp) that were only detectable with the flanking probe highlighting the potential for divergent results using different Southern blotting protocols that could complicate genotype–phenotype correlation studies. Further, we characterize a new C9orf72 antibody and show for the first time decreased C9orf72 protein levels in the frontal cortex from patients with a pathological hexanucleotide repeat expansion. These data suggest that a reduction in C9orf72 protein may be a consequence of the disease.
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Affiliation(s)
- Adrian J Waite
- Institute of Psychological Medicine and Clinical Neurosciences, MRC Centre for Neuropsychiatric Genetics and Genomics, School of Medicine, Cardiff University, Cathays, Cardiff, UK.
| | - Dirk Bäumer
- Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford, UK
| | - Simon East
- Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford, UK
| | - James Neal
- Department of Pathology, School of Medicine, Cardiff University, Cardiff, UK
| | - Huw R Morris
- Department of Clinical Neuroscience, UCL Institute of Neurology, Royal Free Hospital, London, UK
| | - Olaf Ansorge
- Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford, UK
| | - Derek J Blake
- Institute of Psychological Medicine and Clinical Neurosciences, MRC Centre for Neuropsychiatric Genetics and Genomics, School of Medicine, Cardiff University, Cathays, Cardiff, UK
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94
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Dupont N, Codogno P. Non-canonical Autophagy: Facts and Prospects. CURRENT PATHOBIOLOGY REPORTS 2013. [DOI: 10.1007/s40139-013-0030-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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