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Pourshafie N, Masati E, Lopez A, Bunker E, Snyder A, Edwards NA, Winkelsas AM, Fischbeck KH, Grunseich C. Altered SYNJ2BP-mediated mitochondrial-ER contacts in motor neuron disease. Neurobiol Dis 2022; 172:105832. [PMID: 35907632 DOI: 10.1016/j.nbd.2022.105832] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Revised: 07/01/2022] [Accepted: 07/22/2022] [Indexed: 11/30/2022] Open
Abstract
Synaptojanin 2 binding protein (SYNJ2BP) is an outer mitochondrial membrane protein with a cytosolic PDZ domain that functions as a cellular signaling hub. Few studies have evaluated its role in disease. Here we use induced pluripotent stem cell (iPSC)-derived motor neurons and post-mortem tissue from patients with two hereditary motor neuron diseases, spinal and bulbar muscular atrophy (SBMA) and amyotrophic lateral sclerosis type 4 (ALS4), and show that SYNJ2BP expression is increased in diseased motor neurons. Similarly, we show that SYNJ2BP expression increases in iPSC-derived motor neurons undergoing stress. Using proteomic analysis, we found that elevated SYNJ2BP alters the cellular distribution of mitochondria and increases mitochondrial-ER membrane contact sites. Furthermore, decreasing SYNJ2BP levels improves mitochondrial oxidative function in the diseased motor neurons. Together, our observations offer new insight into the molecular pathology of motor neuron disease and the role of SYNJ2BP in mitochondrial dysfunction.
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Affiliation(s)
- Naemeh Pourshafie
- Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA.
| | - Ester Masati
- Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA.
| | - Amber Lopez
- Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
| | - Eric Bunker
- Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA.
| | - Allison Snyder
- Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA.
| | - Nancy A Edwards
- Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA.
| | - Audrey M Winkelsas
- Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA.
| | - Kenneth H Fischbeck
- Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA.
| | - Christopher Grunseich
- Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA.
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2
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Pourshafie N, Masati E, Bunker E, Nickolls AR, Thepmankorn P, Johnson K, Feng X, Ekins T, Grunseich C, Fischbeck KH. Linking epigenetic dysregulation, mitochondrial impairment, and metabolic dysfunction in SBMA motor neurons. JCI Insight 2020; 5:136539. [PMID: 32641584 PMCID: PMC7406250 DOI: 10.1172/jci.insight.136539] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Accepted: 05/21/2020] [Indexed: 12/19/2022] Open
Abstract
Spinal and bulbar muscular atrophy (SBMA) is a neuromuscular disorder caused by a polyglutamine expansion in the androgen receptor (AR). Using gene expression analysis and ChIP sequencing, we mapped transcriptional changes in genetically engineered patient stem cell-derived motor neurons. We found that transcriptional dysregulation in SBMA can occur through AR-mediated histone modification. We detected reduced histone acetylation, along with decreased expression of genes encoding compensatory metabolic proteins and reduced substrate availability for mitochondrial function. Furthermore, we found that pyruvate supplementation corrected this deficiency and improved mitochondrial function and SBMA motor neuron viability. We propose that epigenetic dysregulation of metabolic genes contributes to reduced mitochondrial ATP production. Our results show a molecular link between altered epigenetic regulation and mitochondrial metabolism that contributes to neurodegeneration.
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Affiliation(s)
- Naemeh Pourshafie
- Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, NIH, Bethesda, Maryland, USA
- George Washington University, Institute of Biomedical Sciences, Washington, DC, USA
| | - Ester Masati
- Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, NIH, Bethesda, Maryland, USA
| | - Eric Bunker
- Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, NIH, Bethesda, Maryland, USA
| | - Alec R. Nickolls
- Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, NIH, Bethesda, Maryland, USA
- Brown University, Department of Neuroscience, Providence, Rhode Island, USA
- National Center for Complementary and Integrative Health, NIH, Bethesda, Maryland, USA
| | - Parisorn Thepmankorn
- Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, NIH, Bethesda, Maryland, USA
| | - Kory Johnson
- Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, NIH, Bethesda, Maryland, USA
| | - Xia Feng
- Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, NIH, Bethesda, Maryland, USA
- Johns Hopkins University, Department of Psychiatry and Behavioral Sciences, Baltimore, Maryland, USA
| | - Tyler Ekins
- Brown University, Department of Neuroscience, Providence, Rhode Island, USA
- Program in Developmental Neuroscience, Eunice Kennedy-Shriver National Institute of Child Health and Human Development, NIH, Bethesda, Maryland, USA
| | - Christopher Grunseich
- Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, NIH, Bethesda, Maryland, USA
| | - Kenneth H. Fischbeck
- Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, NIH, Bethesda, Maryland, USA
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3
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Zhang C, Wang R, Liu Z, Bunker E, Lee S, Giuntini M, Chapnick D, Liu X. The plant triterpenoid celastrol blocks PINK1-dependent mitophagy by disrupting PINK1's association with the mitochondrial protein TOM20. J Biol Chem 2019; 294:7472-7487. [PMID: 30885942 DOI: 10.1074/jbc.ra118.006506] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2018] [Revised: 03/05/2019] [Indexed: 12/31/2022] Open
Abstract
A critical function of the PTEN-induced kinase 1 (PINK1)-Parkin pathway is to mediate the clearing of unhealthy or damaged mitochondria via mitophagy. Loss of either PINK1 or Parkin protein expression is associated with Parkinson's disease. Here, using a high-throughput screening approach along with recombinant protein expression and kinase, immunoblotting, and immunofluorescence live-cell imaging assays, we report that celastrol, a pentacyclic triterpenoid isolated from extracts of the medicinal plant Tripterygium wilfordii, blocks recruitment pof Parkin to mitochondria, preventing mitophagy in response to mitochondrial depolarization induced by carbonyl cyanide m-chlorophenylhydrazone or to gamitrinib-induced inhibition of mitochondrial heat shock protein 90 (HSP90). Celastrol's effect on mitophagy was independent of its known role in microtubule disruption. Instead, we show that celastrol suppresses Parkin recruitment by inactivating PINK1 and preventing it from phosphorylating Parkin and also ubiquitin. We also observed that PINK1 directly and strongly associates with TOM20, a component of the translocase of outer mitochondrial membrane (TOM) machinery and relatively weak binding to another TOM subunit, TOM70. Moreover, celastrol disrupted binding between PINK1 and TOM20 both in vitro and in vivo but did not affect binding between TOM20 and TOM70. Using native gel analysis, we also show that celastrol disrupts PINK1 complex formation upon mitochondrial depolarization and sequesters PINK1 to high-molecular-weight protein aggregates. These results reveal that celastrol regulates the mitochondrial quality control pathway by interfering with PINK1-TOM20 binding.
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Affiliation(s)
- Conggang Zhang
- From the Department of Biochemistry, JSCBB, University of Colorado, Boulder, Colorado 80303 and
| | - Rongchun Wang
- From the Department of Biochemistry, JSCBB, University of Colorado, Boulder, Colorado 80303 and.,the Biology Institute, Qilu University of Technology, Shandong Academy of Sciences, 28789 East Jinshi Street, Licheng District, Jinan 250103, China
| | - Zeyu Liu
- From the Department of Biochemistry, JSCBB, University of Colorado, Boulder, Colorado 80303 and
| | - Eric Bunker
- From the Department of Biochemistry, JSCBB, University of Colorado, Boulder, Colorado 80303 and
| | - Schuyler Lee
- From the Department of Biochemistry, JSCBB, University of Colorado, Boulder, Colorado 80303 and
| | - Michelle Giuntini
- From the Department of Biochemistry, JSCBB, University of Colorado, Boulder, Colorado 80303 and
| | - Douglas Chapnick
- From the Department of Biochemistry, JSCBB, University of Colorado, Boulder, Colorado 80303 and
| | - Xuedong Liu
- From the Department of Biochemistry, JSCBB, University of Colorado, Boulder, Colorado 80303 and
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4
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Vargas JNS, Wang C, Bunker E, Hao L, Maric D, Schiavo G, Randow F, Youle RJ. Spatiotemporal Control of ULK1 Activation by NDP52 and TBK1 during Selective Autophagy. Mol Cell 2019; 74:347-362.e6. [PMID: 30853401 PMCID: PMC6642318 DOI: 10.1016/j.molcel.2019.02.010] [Citation(s) in RCA: 277] [Impact Index Per Article: 55.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Revised: 12/26/2018] [Accepted: 02/06/2019] [Indexed: 01/01/2023]
Abstract
Selective autophagy recycles damaged organelles and clears intracellular pathogens to prevent their aberrant accumulation. How ULK1 kinase is targeted and activated during selective autophagic events remains to be elucidated. In this study, we used chemically inducible dimerization (CID) assays in tandem with CRISPR KO lines to systematically analyze the molecular basis of selective autophagosome biogenesis. We demonstrate that ectopic placement of NDP52 on mitochondria or peroxisomes is sufficient to initiate selective autophagy by focally localizing and activating the ULK1 complex. The capability of NDP52 to induce mitophagy is dependent on its interaction with the FIP200/ULK1 complex, which is facilitated by TBK1. Ectopically tethering ULK1 to cargo bypasses the requirement for autophagy receptors and TBK1. Focal activation of ULK1 occurs independently of AMPK and mTOR. Our findings provide a parsimonious model of selective autophagy, which highlights the coordination of ULK1 complex localization by autophagy receptors and TBK1 as principal drivers of targeted autophagosome biogenesis. NDP52 associates with the ULK1 complex through FIP200, facilitated by TBK1 NDP52/TBK1 targets ULK1 to cargo to initiate autophagy in the absence of LC3 ULK1 is activated on cargo independently of AMPK and mTOR activity Ectopic recruitment of FIP200-binding peptide is sufficient to degrade cargo
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Affiliation(s)
- Jose Norberto S Vargas
- Biochemistry Section, Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA; Department of Neuromuscular Disorders, UCL Institute of Neurology, University College London, London WC1N 3BG, UK
| | - Chunxin Wang
- Biochemistry Section, Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
| | - Eric Bunker
- Biochemistry Section, Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
| | - Ling Hao
- Biochemistry Section, Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
| | - Dragan Maric
- Flow and Imaging Cytometry Core Facility, National Institute of Neurological Diseases and Stroke, Bethesda, MD 20892, USA
| | - Giampietro Schiavo
- Department of Neuromuscular Disorders, UCL Institute of Neurology, University College London, London WC1N 3BG, UK; UK Dementia Research Institute at UCL, UCL Queen Square Institute of Neurology, University College London, London WC1E 6BT, UK; Discoveries Centre for Regenerative and Precision Medicine, UCL Campus, University College London, London WC1E 6BT, UK
| | - Felix Randow
- MRC Laboratory of Molecular Biology, Division of Protein and Nucleic Acid Chemistry, Francis Crick Avenue, Cambridge CB2 0QH, UK; University of Cambridge, Department of Medicine, Addenbrooke's Hospital, Cambridge CB2 0QQ, UK
| | - Richard J Youle
- Biochemistry Section, Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA.
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5
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Sekine S, Wang C, Sideris DP, Bunker E, Zhang Z, Youle RJ. Reciprocal Roles of Tom7 and OMA1 during Mitochondrial Import and Activation of PINK1. Mol Cell 2019; 73:1028-1043.e5. [DOI: 10.1016/j.molcel.2019.01.002] [Citation(s) in RCA: 87] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2018] [Revised: 11/05/2018] [Accepted: 12/28/2018] [Indexed: 12/26/2022]
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6
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Chapnick DA, Bunker E, Liu X, Old WM. Temporal Metabolite, Ion, and Enzyme Activity Profiling Using Fluorescence Microscopy and Genetically Encoded Biosensors. Methods Mol Biol 2019; 1978:343-353. [PMID: 31119673 DOI: 10.1007/978-1-4939-9236-2_21] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Living cells employ complex and highly dynamic signaling networks and transcriptional circuits to maintain homeostasis and respond appropriately to constantly changing environments. These networks enable cells to maintain tight control on intracellular concentrations of ions, metabolites, proteins, and other biomolecules and ensure a careful balance between a cell's energetic needs and catabolic processes required for growth. Establishing molecular mechanisms of genetic and pharmacological perturbations remains challenging, due to the interconnected nature of these networks and the extreme sensitivity of cellular systems to their external environment. Live cell imaging with genetically encoded fluorescent biosensors provides a powerful new modality for nondestructive spatiotemporal tracking of ions, small molecules, enzymatic activities, and molecular interactions in living systems, from cells, tissues, and even living organisms. By deploying large panels of cell lines, each with distinct biosensors, many critical biochemical pathways can be monitored in a highly parallel and high-throughput fashion to identify pharmacological vulnerabilities and combination therapies unique to a given cell type or genetic background. Here we describe the experimental and analytical methods required to conduct multiplexed parallel fluorescence microscopy experiments on live cells expressing stable transgenic synthetic protein biosensors.
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Affiliation(s)
| | - Eric Bunker
- Department of Biochemistry, University of Colorado, Boulder, CO, USA
| | - Xuedong Liu
- Department of Biochemistry, University of Colorado, Boulder, CO, USA
| | - William M Old
- Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, CO, USA.
- Linda Crnic Institute for Down Syndrome, University of Colorado School of Medicine, Aurora, CO, USA.
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7
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Li Y, Jin K, Bunker E, Zhang X, Luo X, Liu X, Hao B. Structural basis of the phosphorylation-independent recognition of cyclin D1 by the SCF FBXO31 ubiquitin ligase. Proc Natl Acad Sci U S A 2018; 115:319-324. [PMID: 29279382 PMCID: PMC5777030 DOI: 10.1073/pnas.1708677115] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Ubiquitin-dependent proteolysis of cyclin D1 is associated with normal and tumor cell proliferation and survival. The SCFFBXO31 (Skp1-Cul1-Rbx1-FBXO31) ubiquitin ligase complex mediates genotoxic stress-induced cyclin D1 degradation. Previous studies have suggested that cyclin D1 levels are maintained at steady state by phosphorylation-dependent nuclear export and subsequent proteolysis in the cytoplasm. Here we present the crystal structures of the Skp1-FBXO31 complex alone and bound to a phosphorylated cyclin D1 C-terminal peptide. FBXO31 possesses a unique substrate-binding domain consisting of two β-barrel motifs, whereas cyclin D1 binds to FBXO31 by tucking its free C-terminal carboxylate tail into an open cavity of the C-terminal FBXO31 β-barrel. Biophysical and functional studies demonstrate that SCFFBXO31 is capable of recruiting and ubiquitinating cyclin D1 in a phosphorylation-independent manner. Our findings provide a conceptual framework for understanding the substrate specificity of the F-box protein FBXO31 and the mechanism of FBXO31-regulated cyclin D1 protein turnover.
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Affiliation(s)
- Yunfeng Li
- Department of Molecular Biology and Biophysics, University of Connecticut Health Center, Farmington, CT 06030
| | - Kai Jin
- Department of Molecular Biology and Biophysics, University of Connecticut Health Center, Farmington, CT 06030
| | - Eric Bunker
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO 80309
| | - Xiaojuan Zhang
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO 80309
| | - Xuemei Luo
- Biomolecular Resource Facility, University of Texas Medical Branch, Galveston, TX 77555
| | - Xuedong Liu
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO 80309
| | - Bing Hao
- Department of Molecular Biology and Biophysics, University of Connecticut Health Center, Farmington, CT 06030;
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8
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Zhang C, Liu Z, Bunker E, Ramirez A, Lee S, Peng Y, Tan AC, Eckhardt SG, Chapnick DA, Liu X. Sorafenib targets the mitochondrial electron transport chain complexes and ATP synthase to activate the PINK1-Parkin pathway and modulate cellular drug response. J Biol Chem 2017; 292:15105-15120. [PMID: 28673964 DOI: 10.1074/jbc.m117.783175] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2017] [Revised: 06/20/2017] [Indexed: 01/07/2023] Open
Abstract
Sorafenib (Nexavar) is a broad-spectrum multikinase inhibitor that proves effective in treating advanced renal-cell carcinoma and liver cancer. Despite its well-characterized mechanism of action on several established cancer-related protein kinases, sorafenib causes variable responses among human tumors, although the cause for this variation is unknown. In an unbiased screening of an oncology drug library, we found that sorafenib activates recruitment of the ubiquitin E3 ligase Parkin to damaged mitochondria. We show that sorafenib inhibits the activity of both complex II/III of the electron transport chain and ATP synthase. Dual inhibition of these complexes, but not inhibition of each individual complex, stabilizes the serine-threonine protein kinase PINK1 on the mitochondrial outer membrane and activates Parkin. Unlike the protonophore carbonyl cyanide m-chlorophenylhydrazone, which activates the mitophagy response, sorafenib treatment triggers PINK1/Parkin-dependent cellular apoptosis, which is attenuated upon Bcl-2 overexpression. In summary, our results reveal a new mechanism of action for sorafenib as a mitocan and suggest that high Parkin activity levels could make tumor cells more sensitive to sorafenib's actions, providing one possible explanation why Parkin may be a tumor suppressor gene. These insights could be useful in developing new rationally designed combination therapies with sorafenib.
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Affiliation(s)
- Conggang Zhang
- From the Department of Chemistry and Biochemistry, University of Colorado at Boulder, Boulder, Colorado 80303 and
| | - Zeyu Liu
- From the Department of Chemistry and Biochemistry, University of Colorado at Boulder, Boulder, Colorado 80303 and
| | - Eric Bunker
- From the Department of Chemistry and Biochemistry, University of Colorado at Boulder, Boulder, Colorado 80303 and
| | - Adrian Ramirez
- From the Department of Chemistry and Biochemistry, University of Colorado at Boulder, Boulder, Colorado 80303 and
| | - Schuyler Lee
- From the Department of Chemistry and Biochemistry, University of Colorado at Boulder, Boulder, Colorado 80303 and
| | - Yinghua Peng
- From the Department of Chemistry and Biochemistry, University of Colorado at Boulder, Boulder, Colorado 80303 and
| | - Aik-Choon Tan
- the Developmental Therapeutics Program, Division of Medical Oncology, Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado 80045
| | - S Gail Eckhardt
- the Developmental Therapeutics Program, Division of Medical Oncology, Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado 80045
| | - Douglas A Chapnick
- From the Department of Chemistry and Biochemistry, University of Colorado at Boulder, Boulder, Colorado 80303 and
| | - Xuedong Liu
- From the Department of Chemistry and Biochemistry, University of Colorado at Boulder, Boulder, Colorado 80303 and
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9
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McQuate SE, Young AM, Silva-Herzog E, Bunker E, Hernandez M, de Chaumont F, Liu X, Detweiler CS, Palmer AE. Long-term live-cell imaging reveals new roles for Salmonella effector proteins SseG and SteA. Cell Microbiol 2016; 19. [PMID: 27376507 DOI: 10.1111/cmi.12641] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2015] [Revised: 06/08/2016] [Accepted: 06/28/2016] [Indexed: 01/18/2023]
Abstract
Salmonella Typhimurium is an intracellular bacterial pathogen that infects both epithelial cells and macrophages. Salmonella effector proteins, which are translocated into the host cell and manipulate host cell components, control the ability to replicate and/or survive in host cells. Due to the complexity and heterogeneity of Salmonella infections, there is growing recognition of the need for single-cell and live-cell imaging approaches to identify and characterize the diversity of cellular phenotypes and how they evolve over time. Here, we establish a pipeline for long-term (17 h) live-cell imaging of infected cells and subsequent image analysis methods. We apply this pipeline to track bacterial replication within the Salmonella-containing vacuole in epithelial cells, quantify vacuolar replication versus survival in macrophages and investigate the role of individual effector proteins in mediating these parameters. This approach revealed that dispersed bacteria can coalesce at later stages of infection, that the effector protein SseG influences the propensity for cytosolic hyper-replication in epithelial cells, and that while SteA only has a subtle effect on vacuolar replication in epithelial cells, it has a profound impact on infection parameters in immunocompetent macrophages, suggesting differential roles for effector proteins in different infection models.
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Affiliation(s)
- Sarah E McQuate
- Department of Chemistry and Biochemistry, BioFrontiers Institute, University of Colorado at Boulder, Boulder, CO, USA
| | - Alexandra M Young
- Department of Chemistry and Biochemistry, BioFrontiers Institute, University of Colorado at Boulder, Boulder, CO, USA
| | - Eugenia Silva-Herzog
- Department of Chemistry and Biochemistry, BioFrontiers Institute, University of Colorado at Boulder, Boulder, CO, USA
| | - Eric Bunker
- Department of Chemistry and Biochemistry, BioFrontiers Institute, University of Colorado at Boulder, Boulder, CO, USA
| | - Mateo Hernandez
- Department of Chemistry and Biochemistry, BioFrontiers Institute, University of Colorado at Boulder, Boulder, CO, USA
| | | | - Xuedong Liu
- Department of Chemistry and Biochemistry, BioFrontiers Institute, University of Colorado at Boulder, Boulder, CO, USA
| | - Corrella S Detweiler
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado at Boulder, Boulder, CO, USA
| | - Amy E Palmer
- Department of Chemistry and Biochemistry, BioFrontiers Institute, University of Colorado at Boulder, Boulder, CO, USA
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10
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Bennett CG, Riemondy K, Chapnick DA, Bunker E, Liu X, Kuersten S, Yi R. Genome-wide analysis of Musashi-2 targets reveals novel functions in governing epithelial cell migration. Nucleic Acids Res 2016; 44:3788-800. [PMID: 27034466 PMCID: PMC4857000 DOI: 10.1093/nar/gkw207] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2016] [Accepted: 03/15/2016] [Indexed: 12/19/2022] Open
Abstract
The Musashi-2 (Msi2) RNA-binding protein maintains stem cell self-renewal and promotes oncogenesis by enhancing cell proliferation in hematopoietic and gastrointestinal tissues. However, it is unclear how Msi2 recognizes and regulates mRNA targets in vivo and whether Msi2 primarily controls cell growth in all cell types. Here we identified Msi2 targets with HITS-CLIP and revealed that Msi2 primarily recognizes mRNA 3′UTRs at sites enriched in multiple copies of UAG motifs in epithelial progenitor cells. RNA-seq and ribosome profiling demonstrated that Msi2 promotes targeted mRNA decay without affecting translation efficiency. Unexpectedly, the most prominent Msi2 targets identified are key regulators that govern cell motility with a high enrichment in focal adhesion and extracellular matrix-receptor interaction, in addition to regulators of cell growth and survival. Loss of Msi2 stimulates epithelial cell migration, increases the number of focal adhesions and also compromises cell growth. These findings provide new insights into the molecular mechanisms of Msi2's recognition and repression of targets and uncover a key function of Msi2 in restricting epithelial cell migration.
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Affiliation(s)
- Christopher G Bennett
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO 80309, USA
| | - Kent Riemondy
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO 80309, USA
| | - Douglas A Chapnick
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO 80309, USA
| | - Eric Bunker
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO 80309, USA
| | - Xuedong Liu
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO 80309, USA
| | - Scott Kuersten
- Illumina Inc., 5602 Research Park Blvd. Suite 200, Madison, WI 53719, USA
| | - Rui Yi
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO 80309, USA
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11
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Chapnick DA, Bunker E, Liu X. A biosensor for the activity of the "sheddase" TACE (ADAM17) reveals novel and cell type-specific mechanisms of TACE activation. Sci Signal 2015; 8:rs1. [PMID: 25714465 DOI: 10.1126/scisignal.2005680] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Diverse environmental conditions stimulate protein "shedding" from the cell surface through proteolytic cleavage. The protease TACE [tumor necrosis factor-α (TNFα)--converting enzyme, encoded by ADAM17] mediates protein shedding, thereby regulating the maturation and release of various extracellular substrates, such as growth factors and cytokines, that induce diverse cellular responses. We developed a FRET (fluorescence resonance energy transfer)-based biosensor called TSen that quantitatively reports the kinetics of TACE activity in live cells. In combination with chemical biology approaches, we used TSen to probe the dependence of TACE activation on the induction of the kinases p38 and ERK (extracellular signal-regulated kinase) in various epithelial cell lines. Using TSen, we found that disruption of the actin cytoskeleton in keratinocytes induced rapid and robust TSen cleavage and the accumulation of TACE at the plasma membrane. Cytoskeletal disruption also increased the cleavage of endogenous TACE substrates, including transforming growth factor-α. Thus, TSen is a useful tool for unraveling the mechanisms underlying the spatiotemporal activation of TACE in live cells.
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Affiliation(s)
- Douglas A Chapnick
- Department of Chemistry and Biochemistry, 596 UCB, University of Colorado, Jennie Smoly Caruthers Biotechnology Building (JSCBB), 3415 Colorado Avenue, Boulder, CO 80303, USA
| | - Eric Bunker
- Department of Chemistry and Biochemistry, 596 UCB, University of Colorado, Jennie Smoly Caruthers Biotechnology Building (JSCBB), 3415 Colorado Avenue, Boulder, CO 80303, USA
| | - Xuedong Liu
- Department of Chemistry and Biochemistry, 596 UCB, University of Colorado, Jennie Smoly Caruthers Biotechnology Building (JSCBB), 3415 Colorado Avenue, Boulder, CO 80303, USA.
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12
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Zhang C, Lee S, Peng Y, Bunker E, Giaime E, Shen J, Zhou Z, Liu X. PINK1 triggers autocatalytic activation of Parkin to specify cell fate decisions. Curr Biol 2014; 24:1854-65. [PMID: 25088558 PMCID: PMC4143385 DOI: 10.1016/j.cub.2014.07.014] [Citation(s) in RCA: 82] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2014] [Revised: 07/03/2014] [Accepted: 07/04/2014] [Indexed: 12/22/2022]
Abstract
BACKGROUND The PINK1-Parkin pathway is known to play important roles in regulating mitochondria dynamics, motility, and quality control. Activation of this pathway can be triggered by a variety of cellular stress signals that cause mitochondrial damage. How this pathway senses different levels of mitochondrial damage and mediates cell fate decisions accordingly is incompletely understood. RESULTS Here, we present evidence that PINK1-Parkin has both cytoprotective and proapoptotic functions. PINK1-Parkin operates as a molecular switch to dictate cell fate decisions in response to different cellular stressors. Cells exposed to severe and irreparable mitochondrial damage agents such as valinomycin can undergo PINK1-Parkin-dependent apoptosis. The proapoptotic response elicited by valinomycin is associated with the degradation of Mcl-1. PINK1 directly phosphorylates Parkin at Ser65 of its Ubl domain and triggers activation of its E3 ligase activity through an autocatalytic mechanism that amplifies its E3 ligase activity toward Mcl-1. CONCLUSIONS Autocatalytic activation of Parkin bolsters its accumulation on mitochondria and apoptotic response to valinomycin. Our results suggest that PINK1-Parkin constitutes a damage-gated molecular switch that governs cellular-context-specific cell fate decisions in response to variable stress stimuli.
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Affiliation(s)
- Conggang Zhang
- Department of Chemistry and Biochemistry, 3415 Colorado Ave, JSCBB, and University of Colorado-Boulder, Boulder, Colorado 80303
| | - Schuyler Lee
- Department of Chemistry and Biochemistry, 3415 Colorado Ave, JSCBB, and University of Colorado-Boulder, Boulder, Colorado 80303
| | - Yinghua Peng
- Department of Chemistry and Biochemistry, 3415 Colorado Ave, JSCBB, and University of Colorado-Boulder, Boulder, Colorado 80303
| | - Eric Bunker
- Department of Chemistry and Biochemistry, 3415 Colorado Ave, JSCBB, and University of Colorado-Boulder, Boulder, Colorado 80303
| | - Emilie Giaime
- Center for Neurologic Diseases, Brigham and Women's Hospital, Program in Neuroscience, Harvard Medical School, New Research Building, Rm 636E 77 Avenue Louis Pasteur, Boston, MA 02115
| | - Jie Shen
- Center for Neurologic Diseases, Brigham and Women's Hospital, Program in Neuroscience, Harvard Medical School, New Research Building, Rm 636E 77 Avenue Louis Pasteur, Boston, MA 02115
| | - Zongyao Zhou
- Department of Chemistry and Biochemistry, 3415 Colorado Ave, JSCBB, and University of Colorado-Boulder, Boulder, Colorado 80303
| | - Xuedong Liu
- Department of Chemistry and Biochemistry, 3415 Colorado Avenue, Jennie Smoly Caruthers Biotechnology Building, University of Colorado Boulder, Boulder, CO 80303, USA.
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13
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Abstract
The pupillary effects of intravenous buprenorphine were studied in eight nondependent male subjects who reported previous opiate use. Buprenorphine (0.3, 0.6, and 1.2 mg) decreased pupil size, the amplitude of the light reflex, and the velocities of constriction and dilation. Significant pupillary effects occurred within 15 min of the injection and persisted for 24 hr. At 48 hr most measures returned to baseline levels. Generally the magnitude of the effect was not dose related although recovery occurred sooner after the lower dose. The time course of the pupillary effects of buprenorphine exceeds duration of its analgesic and subjective effects. Previous studies have reported that pupillary measures are especially sensitive to the acute effects of full opiate agonists. The results of the present study indicate that buprenorphine, a partial opiate agonist, causes profound and persistent effects on pupillary size and dynamic measures.
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Affiliation(s)
- W B Pickworth
- National Institute on Drug Abuse, Addiction Research Center, Baltimore, Maryland
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14
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Abstract
A computer program simulates the changes in a nerve's histogram during normal growth and from various neuropathies. The program shows how a nerve's histogram will change from various percentages of fiber damage or from preferential damage to either thick or thin fibers, or from various degrees of fiber restitution, or from single-event or repetitive damage. In single-event damage, the main alteration is a preponderance of thin (regenerating) fibers. Patterns of selective fiber vulnerability are difficult to deduce from the shape of the histogram. Repetitive damage remodels the histogram to a broad unimodal fiber distribution at reduced mean caliber. Comparison of simulated changes with data from an experimental isoniazid neuropathy yielded a close match between observed changes and simulation.
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Affiliation(s)
- E Bunker
- Abteilung für Neuropathologie, Universität Göttingen, Federal Republic of Germany
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15
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Bunker E. A survey of hearing defects in students of four Eastern Highlands high schools. P N G Med J 1983; 26:29-32. [PMID: 6585097] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Unrecognized physical defects may result in educational problems. The Guidance Branch of the Education Department in collaboration with the Papua New Guinea Institute of Medical Research has demonstrated that screening for hearing loss in high school students in the Highlands by Guidance Branch officers is feasible. Six percent of students in their first year at four Eastern Highlands High Schools were found to have significant hearing loss in at least one ear.
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