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Khan D, Ramachandiran I, Vasu K, China A, Khan K, Cumbo F, Halawani D, Terenzi F, Zin I, Long B, Costain G, Blaser S, Carnevale A, Gogonea V, Dutta R, Blankenberg D, Yoon G, Fox PL. Homozygous EPRS1 missense variant causing hypomyelinating leukodystrophy-15 alters variant-distal mRNA m 6A site accessibility. Nat Commun 2024; 15:4284. [PMID: 38769304 PMCID: PMC11106242 DOI: 10.1038/s41467-024-48549-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [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: 10/15/2023] [Accepted: 05/03/2024] [Indexed: 05/22/2024] Open
Abstract
Hypomyelinating leukodystrophy (HLD) is an autosomal recessive disorder characterized by defective central nervous system myelination. Exome sequencing of two siblings with severe cognitive and motor impairment and progressive hypomyelination characteristic of HLD revealed homozygosity for a missense single-nucleotide variant (SNV) in EPRS1 (c.4444 C > A; p.Pro1482Thr), encoding glutamyl-prolyl-tRNA synthetase, consistent with HLD15. Patient lymphoblastoid cell lines express markedly reduced EPRS1 protein due to dual defects in nuclear export and cytoplasmic translation of variant EPRS1 mRNA. Variant mRNA exhibits reduced METTL3 methyltransferase-mediated writing of N6-methyladenosine (m6A) and reduced reading by YTHDC1 and YTHDF1/3 required for efficient mRNA nuclear export and translation, respectively. In contrast to current models, the variant does not alter the sequence of m6A target sites, but instead reduces their accessibility for modification. The defect was rescued by antisense morpholinos predicted to expose m6A sites on target EPRS1 mRNA, or by m6A modification of the mRNA by METTL3-dCas13b, a targeted RNA methylation editor. Our bioinformatic analysis predicts widespread occurrence of SNVs associated with human health and disease that similarly alter accessibility of distal mRNA m6A sites. These results reveal a new RNA-dependent etiologic mechanism by which SNVs can influence gene expression and disease, consequently generating opportunities for personalized, RNA-based therapeutics targeting these disorders.
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Affiliation(s)
- Debjit Khan
- Department of Cardiovascular and Metabolic Sciences, Cleveland Clinic, Lerner Research Institute, Cleveland, OH, USA
| | - Iyappan Ramachandiran
- Department of Cardiovascular and Metabolic Sciences, Cleveland Clinic, Lerner Research Institute, Cleveland, OH, USA
| | - Kommireddy Vasu
- Department of Cardiovascular and Metabolic Sciences, Cleveland Clinic, Lerner Research Institute, Cleveland, OH, USA
| | - Arnab China
- Department of Cardiovascular and Metabolic Sciences, Cleveland Clinic, Lerner Research Institute, Cleveland, OH, USA
| | - Krishnendu Khan
- Department of Cardiovascular and Metabolic Sciences, Cleveland Clinic, Lerner Research Institute, Cleveland, OH, USA
| | - Fabio Cumbo
- Genomic Medicine Institute, Cleveland Clinic, Lerner Research Institute, Cleveland, OH, USA
| | - Dalia Halawani
- Department of Cardiovascular and Metabolic Sciences, Cleveland Clinic, Lerner Research Institute, Cleveland, OH, USA
| | - Fulvia Terenzi
- Department of Cardiovascular and Metabolic Sciences, Cleveland Clinic, Lerner Research Institute, Cleveland, OH, USA
| | - Isaac Zin
- Department of Cardiovascular and Metabolic Sciences, Cleveland Clinic, Lerner Research Institute, Cleveland, OH, USA
- Department of Chemistry, Cleveland State University, Cleveland, OH, USA
| | - Briana Long
- Department of Cardiovascular and Metabolic Sciences, Cleveland Clinic, Lerner Research Institute, Cleveland, OH, USA
| | - Gregory Costain
- Department of Paediatrics, Division of Clinical and Metabolic Genetics, The Hospital for Sick Children, University of Toronto, Toronto, ON, Canada
| | - Susan Blaser
- Department of Diagnostic Imaging, Division of Neuroradiology, The Hospital for Sick Children, University of Toronto, Toronto, ON, Canada
| | - Amanda Carnevale
- Department of Paediatrics, Division of Clinical and Metabolic Genetics, The Hospital for Sick Children, University of Toronto, Toronto, ON, Canada
| | - Valentin Gogonea
- Department of Chemistry, Cleveland State University, Cleveland, OH, USA
| | - Ranjan Dutta
- Department of Neuroscience, Cleveland Clinic, Lerner Research Institute, Cleveland, OH, USA
| | - Daniel Blankenberg
- Genomic Medicine Institute, Cleveland Clinic, Lerner Research Institute, Cleveland, OH, USA
| | - Grace Yoon
- Department of Paediatrics, Division of Clinical and Metabolic Genetics, The Hospital for Sick Children, University of Toronto, Toronto, ON, Canada.
- Department of Paediatrics, Division of Neurology, The Hospital for Sick Children, University of Toronto, Toronto, ON, Canada.
| | - Paul L Fox
- Department of Cardiovascular and Metabolic Sciences, Cleveland Clinic, Lerner Research Institute, Cleveland, OH, USA.
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Wang Y, Halawani D, Estill M, Ramakrishnan A, Shen L, Friedel RH, Zou H. Aryl hydrocarbon receptor restricts axon regeneration of DRG neurons in response to injury. bioRxiv 2023:2023.11.04.565649. [PMID: 37961567 PMCID: PMC10635160 DOI: 10.1101/2023.11.04.565649] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
Injured neurons sense environmental cues to balance neural protection and axon regeneration, but the mechanisms are unclear. Here, we unveil aryl hydrocarbon receptor (AhR), a ligand-activated bHLH-PAS transcription factor, as molecular sensor and key regulator of acute stress response at the expense of axon regeneration. We demonstrate responsiveness of DRG sensory neurons to ligand-mediated AhR signaling, which functions to inhibit axon regeneration. Ahr deletion mimics the conditioning lesion in priming DRG to initiate axonogenesis gene programs; upon peripheral axotomy, Ahr ablation suppresses inflammation and stress signaling while augmenting pro-growth pathways. Moreover, comparative transcriptomics revealed signaling interactions between AhR and HIF-1α, two structurally related bHLH-PAS α units that share the dimerization partner Arnt/HIF-1β. Functional assays showed that the growth advantage of AhR-deficient DRG neurons requires HIF-1α; but in the absence of Arnt, DRG neurons can still mount a regenerative response. We further unveil a link between bHLH-PAS transcription factors and DNA hydroxymethylation in response to peripheral axotomy, while neuronal single cell RNA-seq analysis revealed a link of the AhR regulon to RNA polymerase III regulation and integrated stress response (ISR). Altogether, AhR activation favors stress coping and inflammation at the expense of axon regeneration; targeting AhR can enhance nerve repair.
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Affiliation(s)
- Yiqun Wang
- Nash Family Department of Neuroscience, Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, USA
- Current address: Sport Medicine Center, Honghui Hospital, Xi’an Jiaotong University, Xi’an, China
| | - Dalia Halawani
- Nash Family Department of Neuroscience, Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, USA
| | - Molly Estill
- Nash Family Department of Neuroscience, Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, USA
| | - Aarthi Ramakrishnan
- Nash Family Department of Neuroscience, Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, USA
| | - Li Shen
- Nash Family Department of Neuroscience, Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, USA
| | - Roland H. Friedel
- Nash Family Department of Neuroscience, Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, USA
- Department of Neurosurgery, Icahn School of Medicine at Mount Sinai, New York, USA
| | - Hongyan Zou
- Nash Family Department of Neuroscience, Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, USA
- Department of Neurosurgery, Icahn School of Medicine at Mount Sinai, New York, USA
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Halawani D, Wang Y, Ramakrishnan A, Estill M, He X, Shen L, Friedel RH, Zou H. Circadian clock regulator Bmal1 gates axon regeneration via Tet3 epigenetics in mouse sensory neurons. Nat Commun 2023; 14:5165. [PMID: 37620297 PMCID: PMC10449865 DOI: 10.1038/s41467-023-40816-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [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: 10/25/2022] [Accepted: 08/11/2023] [Indexed: 08/26/2023] Open
Abstract
Axon regeneration of dorsal root ganglia (DRG) neurons after peripheral axotomy involves reconfiguration of gene regulatory circuits to establish regenerative gene programs. However, the underlying mechanisms remain unclear. Here, through an unbiased survey, we show that the binding motif of Bmal1, a central transcription factor of the circadian clock, is enriched in differentially hydroxymethylated regions (DhMRs) of mouse DRG after peripheral lesion. By applying conditional deletion of Bmal1 in neurons, in vitro and in vivo neurite outgrowth assays, as well as transcriptomic profiling, we demonstrate that Bmal1 inhibits axon regeneration, in part through a functional link with the epigenetic factor Tet3. Mechanistically, we reveal that Bmal1 acts as a gatekeeper of neuroepigenetic responses to axonal injury by limiting Tet3 expression and restricting 5hmC modifications. Bmal1-regulated genes not only concern axon growth, but also stress responses and energy homeostasis. Furthermore, we uncover an epigenetic rhythm of diurnal oscillation of Tet3 and 5hmC levels in DRG neurons, corresponding to time-of-day effect on axon growth potential. Collectively, our studies demonstrate that targeting Bmal1 enhances axon regeneration.
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Affiliation(s)
- Dalia Halawani
- Nash Family Department of Neuroscience, Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Yiqun Wang
- Nash Family Department of Neuroscience, Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Department of Orthopedics, Second Affiliated Hospital of Xi'an Jiaotong University, Shaanxi, China
| | - Aarthi Ramakrishnan
- Nash Family Department of Neuroscience, Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Molly Estill
- Nash Family Department of Neuroscience, Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Xijing He
- Department of Orthopedics, Second Affiliated Hospital of Xi'an Jiaotong University, Shaanxi, China
- Department of Orthopedics, Xi'an International Medical Center Hospital, Xi'an, China
| | - Li Shen
- Nash Family Department of Neuroscience, Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Roland H Friedel
- Nash Family Department of Neuroscience, Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Department of Neurosurgery, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Hongyan Zou
- Nash Family Department of Neuroscience, Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
- Department of Neurosurgery, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
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Li Y, Kang S, Halawani D, Wang Y, Junqueira Alves C, Ramakrishnan A, Estill M, Shen L, Li F, He X, Friedel RH, Zou H. Macrophages facilitate peripheral nerve regeneration by organizing regeneration tracks through Plexin-B2. Genes Dev 2022; 36:133-148. [PMID: 35086862 PMCID: PMC8887133 DOI: 10.1101/gad.349063.121] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2021] [Accepted: 01/05/2022] [Indexed: 11/25/2022]
Abstract
In this study, Li et al. investigated the mechanisms underlying the regeneration of peripheral nerves, which is guided by regeneration tracks formed through an interplay of many cell types. They demonstrate that macrophages are mobilized ahead of Schwann cells in the nerve bridge after transection injury to participate in building regeneration tracks. This requires the function of guidance receptor Plexin-B2, which is robustly up-regulated in infiltrating macrophages in injured nerve. The regeneration of peripheral nerves is guided by regeneration tracks formed through an interplay of many cell types, but the underlying signaling pathways remain unclear. Here, we demonstrate that macrophages are mobilized ahead of Schwann cells in the nerve bridge after transection injury to participate in building regeneration tracks. This requires the function of guidance receptor Plexin-B2, which is robustly up-regulated in infiltrating macrophages in injured nerves. Conditional deletion of Plexin-B2 in myeloid lineage resulted in not only macrophage misalignment but also matrix disarray and Schwann cell disorganization, leading to misguided axons and delayed functional recovery. Plexin-B2 is not required for macrophage recruitment or activation but enables macrophages to steer clear of colliding axons, in particular the growth cones at the tip of regenerating axons, leading to parallel alignment postcollision. Together, our studies unveil a novel reparative function of macrophages and the importance of Plexin-B2-mediated collision-dependent contact avoidance between macrophages and regenerating axons in forming regeneration tracks during peripheral nerve regeneration.
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Affiliation(s)
- Yuhuan Li
- Department of Orthopedics, the Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi 710004, China.,Nash Family Department of Neuroscience, Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, New York 10029, USA
| | - Sangjo Kang
- Nash Family Department of Neuroscience, Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, New York 10029, USA
| | - Dalia Halawani
- Nash Family Department of Neuroscience, Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, New York 10029, USA
| | - Yiqun Wang
- Department of Orthopedics, the Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi 710004, China.,Nash Family Department of Neuroscience, Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, New York 10029, USA
| | - Chrystian Junqueira Alves
- Nash Family Department of Neuroscience, Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, New York 10029, USA
| | - Aarthi Ramakrishnan
- Nash Family Department of Neuroscience, Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, New York 10029, USA
| | - Molly Estill
- Nash Family Department of Neuroscience, Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, New York 10029, USA
| | - Li Shen
- Nash Family Department of Neuroscience, Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, New York 10029, USA
| | - Fengtao Li
- Department of Orthopedics, the Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi 710004, China
| | - Xijing He
- Department of Orthopedics, the Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi 710004, China.,Department of Orthopedics, Xi'an International Medical Center Hospital, Xi'an, Shaanxi 710065, China
| | - Roland H Friedel
- Nash Family Department of Neuroscience, Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, New York 10029, USA.,Department of Neurosurgery, Icahn School of Medicine at Mount Sinai, New York, New York 10029, USA
| | - Hongyan Zou
- Nash Family Department of Neuroscience, Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, New York 10029, USA.,Department of Neurosurgery, Icahn School of Medicine at Mount Sinai, New York, New York 10029, USA
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5
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Wahane S, Halawani D, Zhou X, Zou H. Epigenetic Regulation Of Axon Regeneration and Glial Activation in Injury Responses. Front Genet 2019; 10:640. [PMID: 31354788 PMCID: PMC6629966 DOI: 10.3389/fgene.2019.00640] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Accepted: 06/18/2019] [Indexed: 12/22/2022] Open
Abstract
Injury to the nervous system triggers a multicellular response in which epigenetic mechanisms play an important role in regulating cell type-specific transcriptional changes. Here, we summarize recent progress in characterizing neuronal intrinsic and extrinsic chromatin reconfigurations and epigenetic changes triggered by axonal injury that shape neuroplasticity and glial functions. We specifically discuss regeneration-associated transcriptional modules comprised of transcription factors and epigenetic regulators that control axon growth competence. We also review epigenetic regulation of neuroinflammation and astroglial responses that impact neural repair. These advances provide a framework for developing epigenetic strategies to maximize adaptive alterations while minimizing maladaptive stress responses in order to enhance axon regeneration and achieve functional recovery after injury.
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Affiliation(s)
- Shalaka Wahane
- Nash Family Department of Neuroscience and Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, United States
| | - Dalia Halawani
- Nash Family Department of Neuroscience and Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, United States
| | - Xiang Zhou
- Nash Family Department of Neuroscience and Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, United States.,Department of Orthopedics, Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China
| | - Hongyan Zou
- Nash Family Department of Neuroscience and Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, United States.,Department of Neurosurgery, Icahn School of Medicine at Mount Sinai, New York, NY, United States
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6
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Halawani D, Gogonea V, DiDonato JA, Pipich V, Yao P, China A, Topbas C, Vasu K, Arif A, Hazen SL, Fox PL. Structural control of caspase-generated glutamyl-tRNA synthetase by appended noncatalytic WHEP domains. J Biol Chem 2018; 293:8843-8860. [PMID: 29643180 DOI: 10.1074/jbc.m117.807503] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [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: 07/19/2017] [Revised: 03/26/2018] [Indexed: 02/02/2023] Open
Abstract
Aminoacyl-tRNA synthetases are ubiquitous, evolutionarily conserved enzymes catalyzing the conjugation of amino acids onto cognate tRNAs. During eukaryotic evolution, tRNA synthetases have been the targets of persistent structural modifications. These modifications can be additive, as in the evolutionary acquisition of noncatalytic domains, or subtractive, as in the generation of truncated variants through regulated mechanisms such as proteolytic processing, alternative splicing, or coding region polyadenylation. A unique variant is the human glutamyl-prolyl-tRNA synthetase (EPRS) consisting of two fused synthetases joined by a linker containing three copies of the WHEP domain (termed by its presence in tryptophanyl-, histidyl-, and glutamyl-prolyl-tRNA synthetases). Here, we identify site-selective proteolysis as a mechanism that severs the linkage between the EPRS synthetases in vitro and in vivo Caspase action targeted Asp-929 in the third WHEP domain, thereby separating the two synthetases. Using a neoepitope antibody directed against the newly exposed C terminus, we demonstrate EPRS cleavage at Asp-929 in vitro and in vivo Biochemical and biophysical characterizations of the N-terminally generated EPRS proteoform containing the glutamyl-tRNA synthetase and most of the linker, including two WHEP domains, combined with structural analysis by small-angle neutron scattering, revealed a role for the WHEP domains in modulating conformations of the catalytic core and GSH-S-transferase-C-terminal-like (GST-C) domain. WHEP-driven conformational rearrangement altered GST-C domain interactions and conferred distinct oligomeric states in solution. Collectively, our results reveal long-range conformational changes imposed by the WHEP domains and illustrate how noncatalytic domains can modulate the global structure of tRNA synthetases in complex eukaryotic systems.
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Affiliation(s)
- Dalia Halawani
- From the Department of Cellular and Molecular Medicine, Lerner Research Institute and
| | - Valentin Gogonea
- From the Department of Cellular and Molecular Medicine, Lerner Research Institute and .,the Department of Chemistry, Cleveland State University, Cleveland, Ohio 44115
| | - Joseph A DiDonato
- From the Department of Cellular and Molecular Medicine, Lerner Research Institute and
| | - Vitaliy Pipich
- the Jülich Center for Neutron Science, Outstation at Maier-Leibnitz Zentrum, Forschungszentrum Jülich, GmbH, Lichtenbergstrasse 1, 85747 Garching, Germany, and
| | - Peng Yao
- the Department of Medicine, Aab Cardiovascular Research Institute, University of Rochester, Rochester, New York 14642
| | - Arnab China
- From the Department of Cellular and Molecular Medicine, Lerner Research Institute and
| | - Celalettin Topbas
- From the Department of Cellular and Molecular Medicine, Lerner Research Institute and.,the Department of Chemistry, Cleveland State University, Cleveland, Ohio 44115
| | - Kommireddy Vasu
- From the Department of Cellular and Molecular Medicine, Lerner Research Institute and
| | - Abul Arif
- From the Department of Cellular and Molecular Medicine, Lerner Research Institute and
| | - Stanley L Hazen
- From the Department of Cellular and Molecular Medicine, Lerner Research Institute and.,Center for Cardiovascular Diagnostics and Prevention, and Department of Cardiovascular Medicine, Cleveland Clinic Foundation, Cleveland, Ohio 44195
| | - Paul L Fox
- From the Department of Cellular and Molecular Medicine, Lerner Research Institute and
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7
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Arif A, Terenzi F, Potdar AA, Jia J, Sacks J, China A, Halawani D, Vasu K, Li X, Brown JM, Chen J, Kozma SC, Thomas G, Fox PL. EPRS is a critical mTORC1-S6K1 effector that influences adiposity in mice. Nature 2017; 542:357-361. [PMID: 28178239 PMCID: PMC5480610 DOI: 10.1038/nature21380] [Citation(s) in RCA: 101] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2015] [Accepted: 01/11/2017] [Indexed: 12/26/2022]
Abstract
Metabolic pathways that contribute to adiposity and ageing are activated by the mammalian target of rapamycin complex 1 (mTORC1) and p70 ribosomal protein S6 kinase 1 (S6K1) axis. However, known mTORC1-S6K1 targets do not account for observed loss-of-function phenotypes, suggesting that there are additional downstream effectors of this pathway. Here we identify glutamyl-prolyl-tRNA synthetase (EPRS) as an mTORC1-S6K1 target that contributes to adiposity and ageing. Phosphorylation of EPRS at Ser999 by mTORC1-S6K1 induces its release from the aminoacyl tRNA multisynthetase complex, which is required for execution of noncanonical functions of EPRS beyond protein synthesis. To investigate the physiological function of EPRS phosphorylation, we generated Eprs knock-in mice bearing phospho-deficient Ser999-to-Ala (S999A) and phospho-mimetic (S999D) mutations. Homozygous S999A mice exhibited low body weight, reduced adipose tissue mass, and increased lifespan, similar to S6K1-deficient mice and mice with adipocyte-specific deficiency of raptor, an mTORC1 constituent. Substitution of the EprsS999D allele in S6K1-deficient mice normalized body mass and adiposity, indicating that EPRS phosphorylation mediates S6K1-dependent metabolic responses. In adipocytes, insulin stimulated S6K1-dependent EPRS phosphorylation and release from the multisynthetase complex. Interaction screening revealed that phospho-EPRS binds SLC27A1 (that is, fatty acid transport protein 1, FATP1), inducing its translocation to the plasma membrane and long-chain fatty acid uptake. Thus, EPRS and FATP1 are terminal mTORC1-S6K1 axis effectors that are critical for metabolic phenotypes.
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Affiliation(s)
- Abul Arif
- Department of Cellular and Molecular Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio 44195, USA
| | - Fulvia Terenzi
- Department of Cellular and Molecular Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio 44195, USA
| | - Alka A Potdar
- F. Widjaja Foundation Inflammatory Bowel and Immunobiology Research Institute, Cedars-Sinai Medical Center, Los Angeles, California 90048, USA
| | - Jie Jia
- Department of Cellular and Molecular Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio 44195, USA
| | - Jessica Sacks
- Department of Cellular and Molecular Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio 44195, USA
| | - Arnab China
- Department of Cellular and Molecular Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio 44195, USA
| | - Dalia Halawani
- Department of Cellular and Molecular Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio 44195, USA
| | - Kommireddy Vasu
- Department of Cellular and Molecular Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio 44195, USA
| | - Xiaoxia Li
- Department of Immunology, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio 44195, USA
| | - J Mark Brown
- Department of Cellular and Molecular Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio 44195, USA
| | - Jie Chen
- Department of Cell and Developmental Biology, University of Illinois, Urbana, Illinois 61801, USA
| | - Sara C Kozma
- Catalan Institute of Oncology, ICO, Bellvitge Biomedical Research Institute, IDIBELL, Barcelona, Spain.,Department of Physiological Sciences II, Faculty of Medicine, University of Barcelona, 08908 Barcelona, Spain
| | - George Thomas
- Catalan Institute of Oncology, ICO, Bellvitge Biomedical Research Institute, IDIBELL, Barcelona, Spain.,Department of Physiological Sciences II, Faculty of Medicine, University of Barcelona, 08908 Barcelona, Spain.,Division of Hematology and Oncology, Department of Internal Medicine, College of Medicine, University of Cincinnati, Cincinnati, Ohio, USA
| | - Paul L Fox
- Department of Cellular and Molecular Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio 44195, USA
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8
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Arif A, Jia J, Halawani D, Fox PL. Experimental approaches for investigation of aminoacyl tRNA synthetase phosphorylation. Methods 2016; 113:72-82. [PMID: 27729295 DOI: 10.1016/j.ymeth.2016.10.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [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: 08/25/2016] [Revised: 10/04/2016] [Accepted: 10/06/2016] [Indexed: 02/04/2023] Open
Abstract
Phosphorylation of many aminoacyl tRNA synthetases (AARSs) has been recognized for decades, but the contribution of post-translational modification to their primary role in tRNA charging and decryption of genetic code remains unclear. In contrast, phosphorylation is essential for performance of diverse noncanonical functions of AARSs unrelated to protein synthesis. Phosphorylation of glutamyl-prolyl tRNA synthetase (EPRS) has been investigated extensively in our laboratory for more than a decade, and has served as an archetype for studies of other AARSs. EPRS is a constituent of the IFN-γ-activated inhibitor of translation (GAIT) complex that directs transcript-selective translational control in myeloid cells. Stimulus-dependent phosphorylation of EPRS is essential for its release from the parental multi-aminoacyl tRNA synthetase complex (MSC), for binding to other GAIT complex proteins, and for regulating the binding to target mRNAs. Importantly, phosphorylation is the common driving force for the context- and stimulus-dependent release, and non-canonical activity, of other AARSs residing in the MSC, for example, lysyl tRNA synthetase (KARS). Here, we describe the concepts and experimental methodologies we have used to investigate the influence of phosphorylation on the structure and function of EPRS. We suggest that application of these approaches will help to identify new functional phosphorylation event(s) in other AARSs and elucidate their possible roles in noncanonical activities.
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Affiliation(s)
- Abul Arif
- Department of Cellular and Molecular Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA
| | - Jie Jia
- Department of Cellular and Molecular Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA
| | - Dalia Halawani
- Department of Cellular and Molecular Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA
| | - Paul L Fox
- Department of Cellular and Molecular Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA.
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9
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Mountassif D, Fabre L, Zaid Y, Halawani D, Rouiller I. Cryo-EM of the pathogenic VCP variant R155P reveals long-range conformational changes in the D2 ATPase ring. Biochem Biophys Res Commun 2015; 468:636-41. [PMID: 26549226 DOI: 10.1016/j.bbrc.2015.11.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [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: 10/23/2015] [Accepted: 11/02/2015] [Indexed: 11/25/2022]
Abstract
Single amino acid mutations in valosin containing protein (VCP/p97), a highly conserved member of the ATPases associated with diverse cellular activities (AAA) family of ATPases has been linked to a severe degenerative disease affecting brain, muscle and bone tissue. Previous studies have demonstrated the role of VCP mutations in altering the ATPase activity of the D2 ring; however the structural consequences of these mutations remain unclear. In this study, we report the three-dimensional (3D) map of the pathogenic VCP variant, R155P, as revealed by single-particle Cryo-Electron Microscopy (EM) analysis at 14 Å resolution. We show that the N-terminal R155P mutation induces a large structural reorganisation of the D2 ATPase ring. Results from docking studies using crystal structure data of available wild-type VCP in the EM density maps indicate that the major difference is localized at the interface between two protomers within the D2 ring. Consistent with a conformational change, the VCP R155P variant shifted the isoelectric point of the protein and reduced its interaction with its well-characterized cofactor, nuclear protein localization-4 (Npl4). Together, our results demonstrate that a single amino acid substitution in the N-terminal domain can relay long-range conformational changes to the distal D2 ATPase ring. Our results provide the first structural clues of how VCP mutations may influence the activity and function of the D2 ATPase ring.
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Affiliation(s)
- Driss Mountassif
- Department of Anatomy and Cell Biology, McGill University, Groupe de recherche axé sur la structure des protéines (GRASP), Groupe d'Étude des Proteines Membranaires (GÉPROM), 3640 University Street, Montreal H3A 0C7, Canada
| | - Lucien Fabre
- Department of Anatomy and Cell Biology, McGill University, Groupe de recherche axé sur la structure des protéines (GRASP), Groupe d'Étude des Proteines Membranaires (GÉPROM), 3640 University Street, Montreal H3A 0C7, Canada
| | - Younes Zaid
- Department of Anatomy and Cell Biology, McGill University, Groupe de recherche axé sur la structure des protéines (GRASP), Groupe d'Étude des Proteines Membranaires (GÉPROM), 3640 University Street, Montreal H3A 0C7, Canada; Current address: Laboratory of Thrombosis and Hemostasis, Montreal Heart Institute, Montreal, Quebec, Canada
| | - Dalia Halawani
- Department of Anatomy and Cell Biology, McGill University, Groupe de recherche axé sur la structure des protéines (GRASP), Groupe d'Étude des Proteines Membranaires (GÉPROM), 3640 University Street, Montreal H3A 0C7, Canada; Current address: Department of Cell Biology, Lerner Research Institute, 9500 Euclid Avenue NC10, Cleveland, OH 44195, USA
| | - Isabelle Rouiller
- Department of Anatomy and Cell Biology, McGill University, Groupe de recherche axé sur la structure des protéines (GRASP), Groupe d'Étude des Proteines Membranaires (GÉPROM), 3640 University Street, Montreal H3A 0C7, Canada.
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Binette J, Dubé M, Mercier J, Halawani D, Latterich M, Cohen EA. Requirements for the selective degradation of CD4 receptor molecules by the human immunodeficiency virus type 1 Vpu protein in the endoplasmic reticulum. Retrovirology 2007; 4:75. [PMID: 17937819 PMCID: PMC2170451 DOI: 10.1186/1742-4690-4-75] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.6] [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: 07/23/2007] [Accepted: 10/15/2007] [Indexed: 01/12/2023] Open
Abstract
Background HIV-1 Vpu targets newly synthesized CD4 receptor for rapid degradation by a process reminiscent of endoplasmic reticulum (ER)-associated protein degradation (ERAD). Vpu is thought to act as an adaptor protein, connecting CD4 to the ubiquitin (Ub)-proteasome degradative system through an interaction with β-TrCP, a component of the SCFβ-TrCP E3 Ub ligase complex. Results Here, we provide direct evidence indicating that Vpu promotes trans-ubiquitination of CD4 through recruitment of SCFβ-TrCP in human cells. To examine whether Ub conjugation occurs on the cytosolic tail of CD4, we substituted all four Ub acceptor lysine residues for arginines. Replacement of cytosolic lysine residues reduced but did not prevent Vpu-mediated CD4 degradation and ubiquitination, suggesting that Vpu-mediated CD4 degradation is not entirely dependent on the ubiquitination of cytosolic lysines and as such might also involve ubiquitination of other sites. Cell fractionation studies revealed that Vpu enhanced the levels of ubiquitinated forms of CD4 detected in association with not only the ER membrane but also the cytosol. Interestingly, significant amounts of membrane-associated ubiquitinated CD4 appeared to be fully dislocated since they could be recovered following sodium carbonate salt treatment. Finally, expression of a transdominant negative mutant of the AAA ATPase Cdc48/p97 involved in the extraction of ERAD substrates from the ER membrane inhibited Vpu-mediated CD4 degradation. Conclusion Taken together, these results are consistent with a model whereby HIV-1 Vpu targets CD4 for degradation by an ERAD-like process involving most likely poly-ubiquitination of the CD4 cytosolic tail by SCFβ-TrCP prior to dislocation of receptor molecules across the ER membrane by a process that depends on the AAA ATPase Cdc48/p97.
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Affiliation(s)
- Julie Binette
- Laboratory of Human Retrovirology, Institut de Recherches Cliniques de Montréal, 110 Avenue des Pins Ouest, Montreal, Quebec H2W 1R7, Canada.
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Abstract
The multifunctional AAA-ATPase p97/VCP is one of the most extensively studied members of this protein family, yet it presents the field with many perplexing questions surrounding its mechanism of substrate engagement and processing. Recent discoveries have unmasked a new purgatorial identity for this molecule in the ubiquitin-proteasome pathway, specifically its role in linking ubiquitylated substrates with competing ubiquitin conjugation and deconjugation machineries. Furthermore, biochemical studies surprisingly identify the C-terminal D2 ring as essential for substrate interaction, thus bringing p97 one step closer to its prokaryotic AAA protease relatives.
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Affiliation(s)
- Dalia Halawani
- Department of Anatomy and Cell Biology, McGill University, 3640 University Street, Montreal, QC H3A 2B2, Canada
| | - Martin Latterich
- Department of Anatomy and Cell Biology, McGill University, 3640 University Street, Montreal, QC H3A 2B2, Canada.
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Abstract
Chondrosarcomas represent the second most frequent class of primary skeletal malignancies. This tumor type is highly resistant to radiation therapy and currently available chemotherapies, thereby limiting treatment choice to surgical resection. Identifying the mechanisms responsible for chondrosarcoma cell proliferation is therefore crucial for the development of new treatment strategies. Here, we demonstrate a significant reduction in rat chondrosarcoma cell proliferation following treatment with pharmacological inhibitors (SB202190 and PD169316) of p38 mitogen-activated protein (MAP) kinases. In an attempt to dissect possible mechanisms, we investigated the effect of p38 inhibition on promoter activity of cell-cycle genes. Surprisingly, p38 inhibition resulted in upregulation of the activities of all three D-type cyclin promoters. In addition, p38 inhibitors induced increased transcription of the cell-cycle inhibitor p21(waf1/cip1). As expected, promoter activity of the cyclin A gene, which lies downstream of D-type cyclins and p21 in cell-cycle progression, was strongly reduced by p38 inhibitors. These effects were independent of a cyclic AMP response element and conferred by the proximal 150 nucleotides of the cyclin A promoter. Decreased transcription was accompanied by greatly reduced cyclin A protein levels upon p38 inhibition. These observations indicate complex regulation of chondrosarcoma cell-cycle progression by p38 signaling, and suggest that components of p38 MAP kinase pathways may be effective targets in the treatment of these tumors.
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Affiliation(s)
- Dalia Halawani
- Department of Physiology and Pharmacology, Canadian Institute of Health Research Group in Skeletal Development and Remodeling, University of Western Ontario, London, Ontario, Canada N6A 5C1
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