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Zheng H, Zhang H. More than a bystander: RNAs specify multifaceted behaviors of liquid-liquid phase-separated biomolecular condensates. Bioessays 2024; 46:e2300203. [PMID: 38175843 DOI: 10.1002/bies.202300203] [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: 10/24/2023] [Revised: 12/09/2023] [Accepted: 12/12/2023] [Indexed: 01/06/2024]
Abstract
Cells contain a myriad of membraneless ribonucleoprotein (RNP) condensates with distinct compositions of proteins and RNAs. RNP condensates participate in different cellular activities, including RNA storage, mRNA translation or decay, stress response, etc. RNP condensates are assembled via liquid-liquid phase separation (LLPS) driven by multivalent interactions. Transition of RNP condensates into bodies with abnormal material properties, such as solid-like amyloid structures, is associated with the pathogenesis of various diseases. In this review, we focus on how RNAs regulate multiple aspects of RNP condensates, such as dynamic assembly and/or disassembly and biophysical properties. RNA properties - including concentration, sequence, length and structure - also determine the phase behaviors of RNP condensates. RNA is also involved in specifying autophagic degradation of RNP condensates. Unraveling the role of RNA in RNPs provides novel insights into pathological accumulation of RNPs in various diseases. This new understanding can potentially be harnessed to develop therapeutic strategies.
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Affiliation(s)
- Hui Zheng
- National Laboratory of Biomacromolecules, New Cornerstone Science Laboratory, Institute of Biophysics, Chinese Academy of Sciences, Beijing, P.R. China
| | - Hong Zhang
- National Laboratory of Biomacromolecules, New Cornerstone Science Laboratory, Institute of Biophysics, Chinese Academy of Sciences, Beijing, P.R. China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, P.R. China
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2
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Lee KP, Liu K, Kim EY, Medina-Puche L, Dong H, Di M, Singh RM, Li M, Qi S, Meng Z, Cho J, Zhang H, Lozano-Duran R, Kim C. The m6A reader ECT1 drives mRNA sequestration to dampen salicylic acid-dependent stress responses in Arabidopsis. Plant Cell 2024; 36:746-763. [PMID: 38041863 PMCID: PMC10896288 DOI: 10.1093/plcell/koad300] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2023] [Revised: 10/31/2023] [Accepted: 10/31/2023] [Indexed: 12/04/2023]
Abstract
N 6-methyladenosine (m6A) is a common epitranscriptional mRNA modification in eukaryotes. Thirteen putative m6A readers, mostly annotated as EVOLUTIONARILY CONSERVED C-TERMINAL REGION (ECT) proteins, have been identified in Arabidopsis (Arabidopsis thaliana), but few have been characterized. Here, we show that the Arabidopsis m6A reader ECT1 modulates salicylic acid (SA)-mediated plant stress responses. ECT1 undergoes liquid-liquid phase separation in vitro, and its N-terminal prion-like domain is critical for forming in vivo cytosolic biomolecular condensates in response to SA or bacterial pathogens. Fluorescence-activated particle sorting coupled with quantitative PCR analyses unveiled that ECT1 sequesters SA-induced m6A modification-prone mRNAs through its conserved aromatic cage to facilitate their decay in cytosolic condensates, thereby dampening SA-mediated stress responses. Consistent with this finding, ECT1 overexpression promotes bacterial multiplication in plants. Collectively, our findings unequivocally link ECT1-associated cytosolic condensates to SA-dependent plant stress responses, advancing the current understanding of m6A readers and the SA signaling network.
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Affiliation(s)
- Keun Pyo Lee
- Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant Sciences (CEMPS), Chinese Academy of Sciences, Shanghai 200032, China
| | - Kaiwei Liu
- Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant Sciences (CEMPS), Chinese Academy of Sciences, Shanghai 200032, China
- University of the Chinese Academy of Sciences, Beijing 100049, China
| | - Eun Yu Kim
- National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences (CEMPS), Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China
| | - Laura Medina-Puche
- Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant Sciences (CEMPS), Chinese Academy of Sciences, Shanghai 200032, China
| | - Haihong Dong
- Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant Sciences (CEMPS), Chinese Academy of Sciences, Shanghai 200032, China
| | - Minghui Di
- Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant Sciences (CEMPS), Chinese Academy of Sciences, Shanghai 200032, China
- University of the Chinese Academy of Sciences, Beijing 100049, China
| | - Rahul Mohan Singh
- Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant Sciences (CEMPS), Chinese Academy of Sciences, Shanghai 200032, China
| | - Mengping Li
- Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant Sciences (CEMPS), Chinese Academy of Sciences, Shanghai 200032, China
| | - Shan Qi
- Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant Sciences (CEMPS), Chinese Academy of Sciences, Shanghai 200032, China
- University of the Chinese Academy of Sciences, Beijing 100049, China
| | - Zhuoling Meng
- Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant Sciences (CEMPS), Chinese Academy of Sciences, Shanghai 200032, China
- University of the Chinese Academy of Sciences, Beijing 100049, China
| | - Jungnam Cho
- National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences (CEMPS), Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China
- CAS-JIC Centre of Excellence for Plant and Microbial Science, Chinese Academy of Sciences, Shanghai 200032, China
| | - Heng Zhang
- Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant Sciences (CEMPS), Chinese Academy of Sciences, Shanghai 200032, China
| | - Rosa Lozano-Duran
- Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant Sciences (CEMPS), Chinese Academy of Sciences, Shanghai 200032, China
| | - Chanhong Kim
- Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant Sciences (CEMPS), Chinese Academy of Sciences, Shanghai 200032, China
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Palazzo AF, Qiu Y, Kang YM. mRNA nuclear export: how mRNA identity features distinguish functional RNAs from junk transcripts. RNA Biol 2024; 21:1-12. [PMID: 38091265 PMCID: PMC10732640 DOI: 10.1080/15476286.2023.2293339] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/05/2023] [Indexed: 12/18/2023] Open
Abstract
The division of the cellular space into nucleoplasm and cytoplasm promotes quality control mechanisms that prevent misprocessed mRNAs and junk RNAs from gaining access to the translational machinery. Here, we explore how properly processed mRNAs are distinguished from both misprocessed mRNAs and junk RNAs by the presence or absence of various 'identity features'.
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Affiliation(s)
| | - Yi Qiu
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Yoon Mo Kang
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
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4
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Li J, Su L, Jiang J, Wang YE, Ling Y, Qiu Y, Yu H, Huang Y, Wu J, Jiang S, Zhang T, Palazzo AF, Shen Q. RanBP2/Nup358 Mediates Sumoylation of STAT1 and Antagonizes Interferon-α-Mediated Antiviral Innate Immunity. Int J Mol Sci 2023; 25:299. [PMID: 38203469 PMCID: PMC10778711 DOI: 10.3390/ijms25010299] [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: 11/15/2023] [Revised: 12/16/2023] [Accepted: 12/20/2023] [Indexed: 01/12/2024] Open
Abstract
Type I interferon (IFN-I)-induced signaling plays a critical role in host antiviral innate immune responses. Despite this, the mechanisms that regulate this signaling pathway have yet to be fully elucidated. The nucleoporin Ran Binding Protein 2 (RanBP2) (also known as Nucleoporin 358 KDa, Nup358) has been implicated in a number of cellular processes, including host innate immune signaling pathways, and is known to influence viral infection. In this study, we documented that RanBP2 mediates the sumoylation of signal transducers and activators of transcription 1 (STAT1) and inhibits IFN-α-induced signaling. Specifically, we found that RanBP2-mediated sumoylation inhibits the interaction of STAT1 and Janus kinase 1 (JAK1), as well as the phosphorylation and nuclear accumulation of STAT1 after IFN-α stimulation, thereby antagonizing the IFN-α-mediated antiviral innate immune signaling pathway and promoting viral infection. Our findings not only provide insights into a novel function of RanBP2 in antiviral innate immunity but may also contribute to the development of new antiviral therapeutic strategies.
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Affiliation(s)
- Jiawei Li
- Department of Immunology, School of Basic Medical Sciences, Fujian Medical University, Fuzhou 350108, China; (J.L.); (L.S.); (J.J.); (Y.L.); (H.Y.); (Y.H.); (J.W.); (S.J.); (T.Z.)
| | - Lili Su
- Department of Immunology, School of Basic Medical Sciences, Fujian Medical University, Fuzhou 350108, China; (J.L.); (L.S.); (J.J.); (Y.L.); (H.Y.); (Y.H.); (J.W.); (S.J.); (T.Z.)
| | - Jing Jiang
- Department of Immunology, School of Basic Medical Sciences, Fujian Medical University, Fuzhou 350108, China; (J.L.); (L.S.); (J.J.); (Y.L.); (H.Y.); (Y.H.); (J.W.); (S.J.); (T.Z.)
| | - Yifan E. Wang
- Department of Biochemistry, University of Toronto, Toronto, ON M5G 1M1, Canada; (Y.E.W.); (Y.Q.)
| | - Yingying Ling
- Department of Immunology, School of Basic Medical Sciences, Fujian Medical University, Fuzhou 350108, China; (J.L.); (L.S.); (J.J.); (Y.L.); (H.Y.); (Y.H.); (J.W.); (S.J.); (T.Z.)
| | - Yi Qiu
- Department of Biochemistry, University of Toronto, Toronto, ON M5G 1M1, Canada; (Y.E.W.); (Y.Q.)
| | - Huahui Yu
- Department of Immunology, School of Basic Medical Sciences, Fujian Medical University, Fuzhou 350108, China; (J.L.); (L.S.); (J.J.); (Y.L.); (H.Y.); (Y.H.); (J.W.); (S.J.); (T.Z.)
| | - Yucong Huang
- Department of Immunology, School of Basic Medical Sciences, Fujian Medical University, Fuzhou 350108, China; (J.L.); (L.S.); (J.J.); (Y.L.); (H.Y.); (Y.H.); (J.W.); (S.J.); (T.Z.)
| | - Jiangmin Wu
- Department of Immunology, School of Basic Medical Sciences, Fujian Medical University, Fuzhou 350108, China; (J.L.); (L.S.); (J.J.); (Y.L.); (H.Y.); (Y.H.); (J.W.); (S.J.); (T.Z.)
| | - Shan Jiang
- Department of Immunology, School of Basic Medical Sciences, Fujian Medical University, Fuzhou 350108, China; (J.L.); (L.S.); (J.J.); (Y.L.); (H.Y.); (Y.H.); (J.W.); (S.J.); (T.Z.)
| | - Tao Zhang
- Department of Immunology, School of Basic Medical Sciences, Fujian Medical University, Fuzhou 350108, China; (J.L.); (L.S.); (J.J.); (Y.L.); (H.Y.); (Y.H.); (J.W.); (S.J.); (T.Z.)
| | - Alexander F. Palazzo
- Department of Biochemistry, University of Toronto, Toronto, ON M5G 1M1, Canada; (Y.E.W.); (Y.Q.)
| | - Qingtang Shen
- Department of Immunology, School of Basic Medical Sciences, Fujian Medical University, Fuzhou 350108, China; (J.L.); (L.S.); (J.J.); (Y.L.); (H.Y.); (Y.H.); (J.W.); (S.J.); (T.Z.)
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Child JR, Hofler AC, Chen Q, Yang BH, Kristofich J, Zheng T, Hannigan MM, Elles AL, Reid DW, Nicchitta CV. Examining SRP pathway function in mRNA localization to the endoplasmic reticulum. RNA 2023; 29:1703-1724. [PMID: 37643813 PMCID: PMC10578483 DOI: 10.1261/rna.079643.123] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2023] [Accepted: 07/17/2023] [Indexed: 08/31/2023]
Abstract
Signal recognition particle (SRP) pathway function in protein translocation across the endoplasmic reticulum (ER) is well established; its role in RNA localization to the ER remains, however, unclear. In current models, mRNAs undergo translation- and SRP-dependent trafficking to the ER, with ER localization mediated via interactions between SRP-bound translating ribosomes and the ER-resident SRP receptor (SR), a heterodimeric complex comprising SRA, the SRP-binding subunit, and SRB, an integral membrane ER protein. To study SRP pathway function in RNA localization, SR knockout (KO) mammalian cell lines were generated and the consequences of SR KO on steady-state and dynamic mRNA localization examined. CRISPR/Cas9-mediated SRPRB KO resulted in profound destabilization of SRA. Pairing siRNA silencing of SRPRA in SRPRB KO cells yielded viable SR KO cells. Steady-state mRNA compositions and ER-localization patterns in parental and SR KO cells were determined by cell fractionation and deep sequencing. Notably, steady-state cytosol and ER mRNA compositions and partitioning patterns were largely unaltered by loss of SR expression. To examine SRP pathway function in RNA localization dynamics, the subcellular trafficking itineraries of newly exported mRNAs were determined by 4-thiouridine (4SU) pulse-labeling/4SU-seq/cell fractionation. Newly exported mRNAs were distinguished by high ER enrichment, with ER localization being SR-independent. Intriguingly, under conditions of translation initiation inhibition, the ER was the default localization site for all newly exported mRNAs. These data demonstrate that mRNA localization to the ER can be uncoupled from the SRP pathway function and reopen questions regarding the mechanism of RNA localization to the ER.
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Affiliation(s)
- Jessica R Child
- Department of Cell Biology, Duke University School of Medicine, Durham, North Carolina 27710, USA
| | - Alex C Hofler
- Department of Biochemistry, Duke University School of Medicine, Durham, North Carolina 27710, USA
| | - Qiang Chen
- Department of Cell Biology, Duke University School of Medicine, Durham, North Carolina 27710, USA
| | - Brenda H Yang
- Department of Cell Biology, Duke University School of Medicine, Durham, North Carolina 27710, USA
| | - JohnCarlo Kristofich
- Department of Cell Biology, Duke University School of Medicine, Durham, North Carolina 27710, USA
| | - Tianli Zheng
- Department of Cell Biology, Duke University School of Medicine, Durham, North Carolina 27710, USA
| | - Molly M Hannigan
- Department of Cell Biology, Duke University School of Medicine, Durham, North Carolina 27710, USA
| | - Andrew L Elles
- Department of Cell Biology, Duke University School of Medicine, Durham, North Carolina 27710, USA
| | - David W Reid
- Department of Cell Biology, Duke University School of Medicine, Durham, North Carolina 27710, USA
| | - Christopher V Nicchitta
- Department of Cell Biology, Duke University School of Medicine, Durham, North Carolina 27710, USA
- Department of Biochemistry, Duke University School of Medicine, Durham, North Carolina 27710, USA
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Abstract
Ran-binding protein 2 (RANBP2)/Nup358 is a nucleoporin and a key component of the nuclear pore complex. Through its multiple functions (e.g., SUMOylation, regulation of nucleocytoplasmic transport) and subcellular localizations (e.g., at the nuclear envelope, kinetochores, annulate lamellae), it is involved in many cellular processes. RANBP2 dysregulation or mutation leads to the development of human pathologies, such as acute necrotizing encephalopathy 1, cancer, neurodegenerative diseases, and it is also involved in viral infections. The chromosomal region containing the RANBP2 gene is highly dynamic, with high structural variation and recombination events that led to the appearance of a gene family called RANBP2 and GCC2 Protein Domains (RGPD), with multiple gene loss/duplication events during ape evolution. Although RGPD homoplasy and maintenance during evolution suggest they might confer an advantage to their hosts, their functions are still unknown and understudied. In this review, we discuss the appearance and importance of RANBP2 in metazoans and its function-related pathologies, caused by an alteration of its expression levels (through promotor activity, post-transcriptional, or post-translational modifications), its localization, or genetic mutations.
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Affiliation(s)
- Sophie Desgraupes
- Institut de Recherche en Infectiologie de Montpellier (IRIM), University of Montpellier, France
| | - Lucie Etienne
- Centre International de Recherche en Infectiologie (CIRI), Inserm U1111, UCBL1, CNRS UMR 5308, ENS de Lyon, Université de Lyon, France
| | - Nathalie J Arhel
- Institut de Recherche en Infectiologie de Montpellier (IRIM), University of Montpellier, France
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7
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Mattola S, Aho V, Bustamante‐Jaramillo LF, Pizzioli E, Kann M, Vihinen‐Ranta M. Nuclear entry and egress of parvoviruses. Mol Microbiol 2022; 118:295-308. [PMID: 35974704 PMCID: PMC9805091 DOI: 10.1111/mmi.14974] [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] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Revised: 08/10/2022] [Accepted: 08/13/2022] [Indexed: 01/09/2023]
Abstract
Parvoviruses are small non-enveloped single-stranded DNA viruses, which depend on host cell nuclear transcriptional and replication machinery. After endosomal exposure of nuclear localization sequence and a phospholipase A2 domain on the capsid surface, and escape into the cytosol, parvovirus capsids enter the nucleus. Due to the small capsid diameter of 18-26 nm, intact capsids can potentially pass into the nucleus through nuclear pore complexes (NPCs). This might be facilitated by active nuclear import, but capsids may also follow an alternative entry pathway that includes activation of mitotic factors and local transient disruption of the nuclear envelope. The nuclear entry is followed by currently undefined events of viral genome uncoating. After genome release, viral replication compartments are initiated and infection proceeds. Parvoviral genomes replicate during cellular S phase followed by nuclear capsid assembly during virus-induced S/G2 cell cycle arrest. Nuclear egress of capsids occurs upon nuclear envelope degradation during apoptosis and cell lysis. An alternative pathway for nuclear export has been described using active transport through the NPC mediated by the chromosome region maintenance 1 protein, CRM1, which is enhanced by phosphorylation of the N-terminal domain of VP2. However, other alternative but not yet uncharacterized nuclear export pathways cannot be excluded.
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Affiliation(s)
- Salla Mattola
- Department of Biological and Environmental ScienceUniversity of JyvaskylaJyvaskylaFinland
| | - Vesa Aho
- Department of Biological and Environmental ScienceUniversity of JyvaskylaJyvaskylaFinland
| | | | - Edoardo Pizzioli
- Department of Infectious Diseases, Institute of BiomedicineUniversity of GothenburgGothenburgSweden
| | - Michael Kann
- Department of Infectious Diseases, Institute of BiomedicineUniversity of GothenburgGothenburgSweden,Sahlgrenska AcademyGothenburgSweden,Department of Clinical MicrobiologyRegion Västra Götaland, Sahlgrenska University HospitalGothenburgSweden
| | - Maija Vihinen‐Ranta
- Department of Biological and Environmental ScienceUniversity of JyvaskylaJyvaskylaFinland
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Bley CJ, Nie S, Mobbs GW, Petrovic S, Gres AT, Liu X, Mukherjee S, Harvey S, Huber FM, Lin DH, Brown B, Tang AW, Rundlet EJ, Correia AR, Chen S, Regmi SG, Stevens TA, Jette CA, Dasso M, Patke A, Palazzo AF, Kossiakoff AA, Hoelz A. Architecture of the cytoplasmic face of the nuclear pore. Science 2022; 376:eabm9129. [PMID: 35679405 DOI: 10.1126/science.abm9129] [Citation(s) in RCA: 52] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
INTRODUCTION The subcellular compartmentalization of eukaryotic cells requires selective transport of folded proteins and protein-nucleic acid complexes. Embedded in nuclear envelope pores, which are generated by the circumscribed fusion of the inner and outer nuclear membranes, nuclear pore complexes (NPCs) are the sole bidirectional gateways for nucleocytoplasmic transport. The ~110-MDa human NPC is an ~1000-protein assembly that comprises multiple copies of ~34 different proteins, collectively termed nucleoporins. The symmetric core of the NPC is composed of an inner ring encircling the central transport channel and outer rings formed by Y‑shaped coat nucleoporin complexes (CNCs) anchored atop both sides of the nuclear envelope. The outer rings are decorated with compartment‑specific asymmetric nuclear basket and cytoplasmic filament nucleoporins, which establish transport directionality and provide docking sites for transport factors and the small guanosine triphosphatase Ran. The cytoplasmic filament nucleoporins also play an essential role in the irreversible remodeling of messenger ribonucleoprotein particles (mRNPs) as they exit the central transport channel. Unsurprisingly, the NPC's cytoplasmic face represents a hotspot for disease‑associated mutations and is commonly targeted by viral virulence factors. RATIONALE Previous studies established a near-atomic composite structure of the human NPC's symmetric core by combining (i) biochemical reconstitution to elucidate the interaction network between symmetric nucleoporins, (ii) crystal and single-particle cryo-electron microscopy structure determination of nucleoporins and nucleoporin complexes to reveal their three-dimensional shape and the molecular details of their interactions, (iii) quantitative docking in cryo-electron tomography (cryo-ET) maps of the intact human NPC to uncover nucleoporin stoichiometry and positioning, and (iv) cell‑based assays to validate the physiological relevance of the biochemical and structural findings. In this work, we extended our approach to the cytoplasmic filament nucleoporins to reveal the near-atomic architecture of the cytoplasmic face of the human NPC. RESULTS Using biochemical reconstitution, we elucidated the protein-protein and protein-RNA interaction networks of the human and Chaetomium thermophilum cytoplasmic filament nucleoporins, establishing an evolutionarily conserved heterohexameric cytoplasmic filament nucleoporin complex (CFNC) held together by a central heterotrimeric coiled‑coil hub that tethers two separate mRNP‑remodeling complexes. Further biochemical analysis and determination of a series of crystal structures revealed that the metazoan‑specific cytoplasmic filament nucleoporin NUP358 is composed of 16 distinct domains, including an N‑terminal S‑shaped α‑helical solenoid followed by a coiled‑coil oligomerization element, numerous Ran‑interacting domains, an E3 ligase domain, and a C‑terminal prolyl‑isomerase domain. Physiologically validated quantitative docking into cryo-ET maps of the intact human NPC revealed that pentameric NUP358 bundles, conjoined by the oligomerization element, are anchored through their N‑terminal domains to the central stalk regions of the CNC, projecting flexibly attached domains as far as ~600 Å into the cytoplasm. Using cell‑based assays, we demonstrated that NUP358 is dispensable for the architectural integrity of the assembled interphase NPC and RNA export but is required for efficient translation. After NUP358 assignment, the remaining 4-shaped cryo‑ET density matched the dimensions of the CFNC coiled‑coil hub, in close proximity to an outer-ring NUP93. Whereas the N-terminal NUP93 assembly sensor motif anchors the properly assembled related coiled‑coil channel nucleoporin heterotrimer to the inner ring, biochemical reconstitution confirmed that the NUP93 assembly sensor is reused in anchoring the CFNC to the cytoplasmic face of the human NPC. By contrast, two C. thermophilum CFNCs are anchored by a divergent mechanism that involves assembly sensors located in unstructured portions of two CNC nucleoporins. Whereas unassigned cryo‑ET density occupies the NUP358 and CFNC binding sites on the nuclear face, docking of the nuclear basket component ELYS established that the equivalent position on the cytoplasmic face is unoccupied, suggesting that mechanisms other than steric competition promote asymmetric distribution of nucleoporins. CONCLUSION We have substantially advanced the biochemical and structural characterization of the asymmetric nucleoporins' architecture and attachment at the cytoplasmic and nuclear faces of the NPC. Our near‑atomic composite structure of the human NPC's cytoplasmic face provides a biochemical and structural framework for elucidating the molecular basis of mRNP remodeling, viral virulence factor interference with NPC function, and the underlying mechanisms of nucleoporin diseases at the cytoplasmic face of the NPC. [Figure: see text].
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Affiliation(s)
- Christopher J Bley
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - Si Nie
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - George W Mobbs
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - Stefan Petrovic
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - Anna T Gres
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - Xiaoyu Liu
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - Somnath Mukherjee
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL 60637, USA
| | - Sho Harvey
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - Ferdinand M Huber
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - Daniel H Lin
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - Bonnie Brown
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - Aaron W Tang
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - Emily J Rundlet
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - Ana R Correia
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - Shane Chen
- Division of Molecular and Cellular Biology, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Saroj G Regmi
- Division of Molecular and Cellular Biology, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Taylor A Stevens
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - Claudia A Jette
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - Mary Dasso
- Division of Molecular and Cellular Biology, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Alina Patke
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - Alexander F Palazzo
- Department of Biochemistry, University of Toronto, Toronto, ON M5G 1M1, Canada
| | - Anthony A Kossiakoff
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL 60637, USA
| | - André Hoelz
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA
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Abstract
Dominant missense mutations in RanBP2/Nup358 cause Acute Necrotizing Encephalopathy (ANE), a pediatric disease where seemingly healthy individuals develop a cytokine storm that is restricted to the central nervous system in response to viral infection. Untreated, this condition leads to seizures, coma, long-term neurological damage and a high rate of mortality. The exact mechanism by which RanBP2 mutations contribute to the development of ANE remains elusive. In November 2021, a number of clinicians and basic scientists presented their work on this disease and on the interactions between RanBP2/Nup358, viral infections, the innate immune response and other cellular processes.
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Affiliation(s)
| | - Jomon Joseph
- National Centre for Cell Science, S.P. Pune University Campus, Pune, India
| | - Ming Lim
- Children's Neurosciences, Evelina London Children's Hospital, and the Department of Women and Children's Health, King's College London, London, UK
| | - Kiran T Thakur
- Department of Neurology, Vagelos College of Physicians and Surgeons, Columbia University Irving Medical Center, and the New York Presbyterian Hospital, New York
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10
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Jiang J, Wang YE, Palazzo AF, Shen Q. Roles of Nucleoporin RanBP2/Nup358 in Acute Necrotizing Encephalopathy Type 1 (ANE1) and Viral Infection. Int J Mol Sci 2022; 23:ijms23073548. [PMID: 35408907 PMCID: PMC8998323 DOI: 10.3390/ijms23073548] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Revised: 03/21/2022] [Accepted: 03/22/2022] [Indexed: 12/23/2022] Open
Abstract
Ran Binding Protein 2 (RanBP2 or Nucleoporin358) is one of the main components of the cytoplasmic filaments of the nuclear pore complex. Mutations in the RANBP2 gene are associated with acute necrotizing encephalopathy type 1 (ANE1), a rare condition where patients experience a sharp rise in cytokine production in response to viral infection and undergo hyperinflammation, seizures, coma, and a high rate of mortality. Despite this, it remains unclear howRanBP2 and its ANE1-associated mutations contribute to pathology. Mounting evidence has shown that RanBP2 interacts with distinct viruses to regulate viral infection. In addition, RanBP2 may regulate innate immune response pathways. This review summarizes recent advances in our understanding of how mutations in RANBP2 contribute to ANE1 and discusses how RanBP2 interacts with distinct viruses and affects viral infection. Recent findings indicate that RanBP2 might be an important therapeutic target, not only in the suppression of ANE1-driven cytokine storms, but also to combat hyperinflammation in response to viral infections.
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Affiliation(s)
- Jing Jiang
- Department of Immunology, School of Basic Medical Sciences, Fujian Medical University, Fuzhou 350108, China;
| | - Yifan E. Wang
- Department of Biochemistry, University of Toronto, Toronto, ON M5G 1M1, Canada;
| | - Alexander F. Palazzo
- Department of Biochemistry, University of Toronto, Toronto, ON M5G 1M1, Canada;
- Correspondence: (A.F.P.); (Q.S.)
| | - Qingtang Shen
- Department of Immunology, School of Basic Medical Sciences, Fujian Medical University, Fuzhou 350108, China;
- Correspondence: (A.F.P.); (Q.S.)
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11
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Shukla P, Mandalla A, Elrick MJ, Venkatesan A. Clinical Manifestations and Pathogenesis of Acute Necrotizing Encephalopathy: The Interface Between Systemic Infection and Neurologic Injury. Front Neurol 2022; 12:628811. [PMID: 35058867 PMCID: PMC8764155 DOI: 10.3389/fneur.2021.628811] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [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: 11/13/2020] [Accepted: 12/02/2021] [Indexed: 12/17/2022] Open
Abstract
Acute necrotizing encephalopathy (ANE) is a devastating neurologic condition that can arise following a variety of systemic infections, including influenza and SARS-CoV-2. Affected individuals typically present with rapid changes in consciousness, focal neurological deficits, and seizures. Neuroimaging reveals symmetric, bilateral deep gray matter lesions, often involving the thalami, with evidence of necrosis and/or hemorrhage. The clinical and radiologic picture must be distinguished from direct infection of the central nervous system by some viruses, and from metabolic and mitochondrial disorders. Outcomes following ANE are poor overall and worse in those with brainstem involvement. Specific management is often directed toward modulating immune responses given the potential role of systemic inflammation and cytokine storm in potentiating neurologic injury in ANE, though benefits of such approaches remain unclear. The finding that many patients have mutations in the nucleoporin gene RANBP2, which encodes a multifunctional protein that plays a key role in nucleocytoplasmic transport, may allow for the development of disease models that provide insights into pathogenic mechanisms and novel therapeutic approaches.
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Affiliation(s)
- Priya Shukla
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Abby Mandalla
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Matthew J Elrick
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Arun Venkatesan
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, United States
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12
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Liu X, Chen X, Xiao M, Zhu Y, Gong R, Liu J, Zeng Q, Xu C, Chen X, Wang F, Cao K. RANBP2 Activates O-GlcNAcylation through Inducing CEBPα-Dependent OGA Downregulation to Promote Hepatocellular Carcinoma Malignant Phenotypes. Cancers (Basel) 2021; 13:3475. [PMID: 34298689 PMCID: PMC8304650 DOI: 10.3390/cancers13143475] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2021] [Revised: 06/25/2021] [Accepted: 06/30/2021] [Indexed: 11/16/2022] Open
Abstract
O-GlcNAcylation is an important post-translational modification (PTM) jointly controlled by O-GlcNAc transferase (OGT) and O-GlcNAcase (OGA). Aberrant hyper-O-GlcNAcylation is reported to yield hepatocellular carcinoma (HCC) malignancy, but the underlying mechanisms of the OGT/OGA imbalance responsible for HCC tumorigenesis remain largely unknown. Here, we report that RAN-binding protein 2 (RANBP2), one of the small ubiquitin-like modifier (SUMO) E3 ligases, contributed to malignant phenotypes in HCC. RANBP2 was found to facilitate CCAAT/enhancer-binding protein alpha (CEBPα) SUMOylation and degradation by direct interplay with CEBPα. As a transcriptional factor, CEBPα was verified to augment OGA transcription, and further experiments demonstrated that RANBP2 enhanced the O-GlcNAc level by downregulating OGA transcription while not affecting OGT expression. Importantly, we provided in vitro and in vivo evidence of HCC malignant phenotypes that RANBP2 triggered through an imbalance of OGT/OGA and subsequent higher O-GlcNAcylation events for oncogenic proteins such as peroxisome proliferative-activated receptor gamma coactivator 1 alpha (PGC1α) in a CEBPα-dependent manner. Altogether, our results show a novel molecular mechanism whereby RANBP2 regulates its function through CEBPα-dependent OGA downregulation to induce a global change in the hyper-O-GlcNAcylation of genes, such as PGC1α, encouraging the further study of promising implications for HCC therapy.
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Affiliation(s)
- Xiaoming Liu
- Department of Oncology, Third Xiangya Hospital of Central South University, Changsha 410013, China; (X.L.); (X.C.); (M.X.); (Y.Z.)
- Department of Gastroenterology, Third Xiangya Hospital of Central South University, Changsha 410013, China; (R.G.); (C.X.); (X.C.); (F.W.)
| | - Xingyu Chen
- Department of Oncology, Third Xiangya Hospital of Central South University, Changsha 410013, China; (X.L.); (X.C.); (M.X.); (Y.Z.)
| | - Mengqing Xiao
- Department of Oncology, Third Xiangya Hospital of Central South University, Changsha 410013, China; (X.L.); (X.C.); (M.X.); (Y.Z.)
| | - Yuxing Zhu
- Department of Oncology, Third Xiangya Hospital of Central South University, Changsha 410013, China; (X.L.); (X.C.); (M.X.); (Y.Z.)
| | - Renjie Gong
- Department of Gastroenterology, Third Xiangya Hospital of Central South University, Changsha 410013, China; (R.G.); (C.X.); (X.C.); (F.W.)
| | - Jianye Liu
- Department of Urology, Third Xiangya Hospital of Central South University, Changsha 410013, China;
| | - Qinghai Zeng
- Department of Dermatology, Third Xiangya Hospital of Central South University, Changsha 410013, China;
| | - Canxia Xu
- Department of Gastroenterology, Third Xiangya Hospital of Central South University, Changsha 410013, China; (R.G.); (C.X.); (X.C.); (F.W.)
| | - Xiong Chen
- Department of Gastroenterology, Third Xiangya Hospital of Central South University, Changsha 410013, China; (R.G.); (C.X.); (X.C.); (F.W.)
| | - Fen Wang
- Department of Gastroenterology, Third Xiangya Hospital of Central South University, Changsha 410013, China; (R.G.); (C.X.); (X.C.); (F.W.)
| | - Ke Cao
- Department of Oncology, Third Xiangya Hospital of Central South University, Changsha 410013, China; (X.L.); (X.C.); (M.X.); (Y.Z.)
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13
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Wang L, Yang W, Li B, Yuan S, Wang F. Response to stress in biological disorders: Implications of stress granule assembly and function. Cell Prolif 2021; 54:e13086. [PMID: 34170048 PMCID: PMC8349659 DOI: 10.1111/cpr.13086] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [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: 01/12/2021] [Revised: 06/06/2021] [Accepted: 06/07/2021] [Indexed: 12/17/2022] Open
Abstract
It is indispensable for cells to adapt and respond to environmental stresses, in order for organisms to survive. Stress granules (SGs) are condensed membrane‐less organelles dynamically formed in the cytoplasm of eukaryotes cells to cope with diverse intracellular or extracellular stress factors, with features of liquid‐liquid phase separation. They are composed of multiple constituents, including translationally stalled mRNAs, translation initiation factors, RNA‐binding proteins and also non‐RNA‐binding proteins. SG formation is triggered by stress stimuli, viral infection and signal transduction, while aberrant assembly of SGs may contribute to tissue degenerative diseases. Recently, a growing body of evidence has emerged on SG response mechanisms for cells facing high temperatures, oxidative stress and osmotic stress. In this review, we aim to summarize factors affecting SGs assembly, present the impact of SGs on germ cell development and other biological processes. We particularly emphasize the significance of recently reported RNA modifications in SG stress responses. In parallel, we also review all current perspectives on the roles of SGs in male germ cells, with a particular focus on the dynamics of SG assembly.
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Affiliation(s)
- Lingjuan Wang
- Institute Reproductive Health, Tongji Medical College, Huazhong University of Science and Technology, Hubei, China
| | - Weina Yang
- Institute Reproductive Health, Tongji Medical College, Huazhong University of Science and Technology, Hubei, China
| | - Bin Li
- Tianjin Medical University General Hospital, Tianjin, China.,State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, China
| | - Shuiqiao Yuan
- Institute Reproductive Health, Tongji Medical College, Huazhong University of Science and Technology, Hubei, China
| | - Fengli Wang
- Institute Reproductive Health, Tongji Medical College, Huazhong University of Science and Technology, Hubei, China
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14
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He Y, Yang Z, Zhao CS, Xiao Z, Gong Y, Li YY, Chen Y, Du Y, Feng D, Altman A, Li Y. T-cell receptor (TCR) signaling promotes the assembly of RanBP2/RanGAP1-SUMO1/Ubc9 nuclear pore subcomplex via PKC-θ-mediated phosphorylation of RanGAP1. eLife 2021; 10:67123. [PMID: 34110283 PMCID: PMC8225385 DOI: 10.7554/elife.67123] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [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: 02/01/2021] [Accepted: 06/03/2021] [Indexed: 01/15/2023] Open
Abstract
The nuclear pore complex (NPC) is the sole and selective gateway for nuclear transport, and its dysfunction has been associated with many diseases. The metazoan NPC subcomplex RanBP2, which consists of RanBP2 (Nup358), RanGAP1-SUMO1, and Ubc9, regulates the assembly and function of the NPC. The roles of immune signaling in regulation of NPC remain poorly understood. Here, we show that in human and murine T cells, following T-cell receptor (TCR) stimulation, protein kinase C-θ (PKC-θ) directly phosphorylates RanGAP1 to facilitate RanBP2 subcomplex assembly and nuclear import and, thus, the nuclear translocation of AP-1 transcription factor. Mechanistically, TCR stimulation induces the translocation of activated PKC-θ to the NPC, where it interacts with and phosphorylates RanGAP1 on Ser504 and Ser506. RanGAP1 phosphorylation increases its binding affinity for Ubc9, thereby promoting sumoylation of RanGAP1 and, finally, assembly of the RanBP2 subcomplex. Our findings reveal an unexpected role of PKC-θ as a direct regulator of nuclear import and uncover a phosphorylation-dependent sumoylation of RanGAP1, delineating a novel link between TCR signaling and assembly of the RanBP2 NPC subcomplex.
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Affiliation(s)
- Yujiao He
- MOE Key Laboratory of Gene Function and Regulation, Guangdong Province Key Laboratory of Pharmaceutical Functional Genes, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Zhiguo Yang
- MOE Key Laboratory of Gene Function and Regulation, Guangdong Province Key Laboratory of Pharmaceutical Functional Genes, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Chen-Si Zhao
- MOE Key Laboratory of Gene Function and Regulation, Guangdong Province Key Laboratory of Pharmaceutical Functional Genes, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Zhihui Xiao
- MOE Key Laboratory of Gene Function and Regulation, Guangdong Province Key Laboratory of Pharmaceutical Functional Genes, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Yu Gong
- MOE Key Laboratory of Gene Function and Regulation, Guangdong Province Key Laboratory of Pharmaceutical Functional Genes, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Yun-Yi Li
- MOE Key Laboratory of Gene Function and Regulation, Guangdong Province Key Laboratory of Pharmaceutical Functional Genes, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Yiqi Chen
- MOE Key Laboratory of Gene Function and Regulation, Guangdong Province Key Laboratory of Pharmaceutical Functional Genes, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Yunting Du
- MOE Key Laboratory of Gene Function and Regulation, Guangdong Province Key Laboratory of Pharmaceutical Functional Genes, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Dianying Feng
- MOE Key Laboratory of Gene Function and Regulation, Guangdong Province Key Laboratory of Pharmaceutical Functional Genes, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Amnon Altman
- Center for Cancer Immunotherapy, La Jolla Institute for Immunology, La Jolla, United States
| | - Yingqiu Li
- MOE Key Laboratory of Gene Function and Regulation, Guangdong Province Key Laboratory of Pharmaceutical Functional Genes, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
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15
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Shen Q, Wang YE, Truong M, Mahadevan K, Wu JJ, Zhang H, Li J, Smith HW, Smibert CA, Palazzo AF. RanBP2/Nup358 enhances miRNA activity by sumoylating Argonautes. PLoS Genet 2021; 17:e1009378. [PMID: 33600493 PMCID: PMC7924746 DOI: 10.1371/journal.pgen.1009378] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Revised: 03/02/2021] [Accepted: 01/25/2021] [Indexed: 02/07/2023] Open
Abstract
Mutations in RanBP2 (also known as Nup358), one of the main components of the cytoplasmic filaments of the nuclear pore complex, contribute to the overproduction of acute necrotizing encephalopathy (ANE1)-associated cytokines. Here we report that RanBP2 represses the translation of the interleukin 6 (IL6) mRNA, which encodes a cytokine that is aberrantly up-regulated in ANE1. Our data indicates that soon after its production, the IL6 messenger ribonucleoprotein (mRNP) recruits Argonautes bound to let-7 microRNA. After this mRNP is exported to the cytosol, RanBP2 sumoylates mRNP-associated Argonautes, thereby stabilizing them and enforcing mRNA silencing. Collectively, these results support a model whereby RanBP2 promotes an mRNP remodelling event that is critical for the miRNA-mediated suppression of clinically relevant mRNAs, such as IL6.
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Affiliation(s)
- Qingtang Shen
- School of Basic Medical Sciences, Fujian Medical University, Fuzhou, Fujian, China
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Yifan E. Wang
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Mathew Truong
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Kohila Mahadevan
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Jingze J. Wu
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Hui Zhang
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Jiawei Li
- School of Basic Medical Sciences, Fujian Medical University, Fuzhou, Fujian, China
| | - Harrison W. Smith
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Craig A. Smibert
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
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16
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Tauber D, Tauber G, Parker R. Mechanisms and Regulation of RNA Condensation in RNP Granule Formation. Trends Biochem Sci 2020; 45:764-778. [PMID: 32475683 PMCID: PMC7211619 DOI: 10.1016/j.tibs.2020.05.002] [Citation(s) in RCA: 102] [Impact Index Per Article: 25.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Revised: 04/20/2020] [Accepted: 05/05/2020] [Indexed: 01/01/2023]
Abstract
Ribonucleoprotein (RNP) granules are RNA-protein assemblies that are involved in multiple aspects of RNA metabolism and are linked to memory, development, and disease. Some RNP granules form, in part, through the formation of intermolecular RNA-RNA interactions. In vitro, such trans RNA condensation occurs readily, suggesting that cells require mechanisms to modulate RNA-based condensation. We assess the mechanisms of RNA condensation and how cells modulate this phenomenon. We propose that cells control RNA condensation through ATP-dependent processes, static RNA buffering, and dynamic post-translational mechanisms. Moreover, perturbations in these mechanisms can be involved in disease. This reveals multiple cellular mechanisms of kinetic and thermodynamic control that maintain the proper distribution of RNA molecules between dispersed and condensed forms.
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Affiliation(s)
- Devin Tauber
- Department of Biochemistry, University of Colorado Boulder, Boulder, CO 80308, USA
| | - Gabriel Tauber
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Roy Parker
- Department of Biochemistry, University of Colorado Boulder, Boulder, CO 80308, USA; Howard Hughes Medical Institute, University of Colorado Boulder, Boulder, CO 80308, USA.
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17
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Huang G, Zhang Y, Zhu X, Zeng C, Wang Q, Zhou Q, Tao Q, Liu M, Lei J, Yan C, Shi Y. Structure of the cytoplasmic ring of the Xenopus laevis nuclear pore complex by cryo-electron microscopy single particle analysis. Cell Res 2020; 30:520-31. [PMID: 32376910 DOI: 10.1038/s41422-020-0319-4] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Accepted: 04/06/2020] [Indexed: 12/20/2022] Open
Abstract
The nuclear pore complex (NPC) exhibits structural plasticity and has only been characterized at local resolutions of up to 15 Å for the cytoplasmic ring (CR). Here we present a single-particle cryo-electron microscopy (cryo-EM) structure of the CR from Xenopus laevis NPC at average resolutions of 5.5–7.9 Å, with local resolutions reaching 4.5 Å. Improved resolutions allow identification and placement of secondary structural elements in the majority of the CR components. The two Y complexes in each CR subunit interact with each other and associate with those from flanking subunits, forming a circular scaffold. Within each CR subunit, the Nup358-containing region wraps around the stems of both Y complexes, likely stabilizing the scaffold. Nup205 connects the short arms of the two Y complexes and associates with the stem of a neighboring Y complex. The Nup214-containing region uses an extended coiled-coil to link Nup85 of the two Y complexes and protrudes into the axial pore of the NPC. These previously uncharacterized structural features reveal insights into NPC assembly.
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18
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Cao X, Jin X, Liu B. The involvement of stress granules in aging and aging-associated diseases. Aging Cell 2020; 19:e13136. [PMID: 32170904 PMCID: PMC7189987 DOI: 10.1111/acel.13136] [Citation(s) in RCA: 52] [Impact Index Per Article: 13.0] [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: 11/11/2019] [Revised: 02/14/2020] [Accepted: 02/20/2020] [Indexed: 12/12/2022] Open
Abstract
Stress granules (SGs) are nonmembrane assemblies formed in cells in response to stress conditions. SGs mainly contain untranslated mRNA and a variety of proteins. RNAs and scaffold proteins with intrinsically disordered regions or RNA-binding domains are essential for the assembly of SGs, and multivalent macromolecular interactions among these components are thought to be the driving forces for SG assembly. The SG assembly process includes regulation through post-translational modification and involvement of the cytoskeletal system. During aging, many intracellular bioprocesses become disrupted by factors such as cellular environmental changes, mitochondrial dysfunction, and decline in the protein quality control system. Such changes could lead to the formation of aberrant SGs, as well as alterations in their maintenance, disassembly, and clearance. These aberrant SGs might in turn promote aging and aging-associated diseases. In this paper, we first review the latest progress on the molecular mechanisms underlying SG assembly and SG functioning under stress conditions. Then, we provide a detailed discussion of the relevance of SGs to aging and aging-associated diseases.
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Affiliation(s)
- Xiuling Cao
- State Key Laboratory of Subtropical Silviculture School of Forestry and Biotechnology Zhejiang A&F University Hangzhou China
| | - Xuejiao Jin
- State Key Laboratory of Subtropical Silviculture School of Forestry and Biotechnology Zhejiang A&F University Hangzhou China
| | - Beidong Liu
- State Key Laboratory of Subtropical Silviculture School of Forestry and Biotechnology Zhejiang A&F University Hangzhou China
- Department of Chemistry and Molecular Biology University of Gothenburg Goteborg Sweden
- Center for Large‐scale Cell‐based Screening Faculty of Science University of Gothenburg Goteborg Sweden
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19
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Tauber D, Tauber G, Khong A, Van Treeck B, Pelletier J, Parker R. Modulation of RNA Condensation by the DEAD-Box Protein eIF4A. Cell 2020; 180:411-426.e16. [PMID: 31928844 DOI: 10.1016/j.cell.2019.12.031] [Citation(s) in RCA: 143] [Impact Index Per Article: 35.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Revised: 11/04/2019] [Accepted: 12/20/2019] [Indexed: 01/12/2023]
Abstract
Stress granules are condensates of non-translating mRNAs and proteins involved in the stress response and neurodegenerative diseases. Stress granules form in part through intermolecular RNA-RNA interactions, and to better understand how RNA-based condensation occurs, we demonstrate that RNA is effectively recruited to the surfaces of RNA or RNP condensates in vitro. We demonstrate that, through ATP-dependent RNA binding, the DEAD-box protein eIF4A reduces RNA condensation in vitro and limits stress granule formation in cells. This defines a function for eIF4A to limit intermolecular RNA-RNA interactions in cells. These results establish an important role for eIF4A, and potentially other DEAD-box proteins, as ATP-dependent RNA chaperones that limit the condensation of RNA, analogous to the function of proteins like HSP70 in combatting protein aggregates.
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Affiliation(s)
- Devin Tauber
- Department of Biochemistry, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Gabriel Tauber
- Department of Biochemistry, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Anthony Khong
- Department of Biochemistry, University of Colorado Boulder, Boulder, CO 80309, USA; Howard Hughes Medical Institute, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Briana Van Treeck
- Department of Biochemistry, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Jerry Pelletier
- Department of Biochemistry, McGill University, Montreal, QC H3G 1Y6, Canada; The Rosalind and Morris Goodman Cancer Research Center and the Department of Oncology, McGill University, Montreal, QC, Canada
| | - Roy Parker
- Department of Biochemistry, University of Colorado Boulder, Boulder, CO 80309, USA; Howard Hughes Medical Institute, University of Colorado Boulder, Boulder, CO 80309, USA.
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20
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Spannl S, Tereshchenko M, Mastromarco GJ, Ihn SJ, Lee HO. Biomolecular condensates in neurodegeneration and cancer. Traffic 2019; 20:890-911. [PMID: 31606941 DOI: 10.1111/tra.12704] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2019] [Revised: 10/03/2019] [Accepted: 10/06/2019] [Indexed: 12/14/2022]
Abstract
The intracellular environment is partitioned into functionally distinct compartments containing specific sets of molecules and reactions. Biomolecular condensates, also referred to as membrane-less organelles, are diverse and abundant cellular compartments that lack membranous enclosures. Molecules assemble into condensates by phase separation; multivalent weak interactions drive molecules to separate from their surroundings and concentrate in discrete locations. Biomolecular condensates exist in all eukaryotes and in some prokaryotes, and participate in various essential house-keeping, stress-response and cell type-specific processes. An increasing number of recent studies link abnormal condensate formation, composition and material properties to a number of disease states. In this review, we discuss current knowledge and models describing the regulation of condensates and how they become dysregulated in neurodegeneration and cancer. Further research on the regulation of biomolecular phase separation will help us to better understand their role in cell physiology and disease.
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Affiliation(s)
- Stephanie Spannl
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Maria Tereshchenko
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | | | - Sean J Ihn
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Hyun O Lee
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
- Canada Research Chairs Program, University of Toronto, Toronto, Ontario, Canada
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21
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Van Treeck B, Parker R. Emerging Roles for Intermolecular RNA-RNA Interactions in RNP Assemblies. Cell 2019; 174:791-802. [PMID: 30096311 DOI: 10.1016/j.cell.2018.07.023] [Citation(s) in RCA: 242] [Impact Index Per Article: 48.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Revised: 07/05/2018] [Accepted: 07/20/2018] [Indexed: 12/22/2022]
Abstract
Eukaryotic cells contain large assemblies of RNA and protein, referred to as ribonucleoprotein (RNP) granules, which include cytoplasmic P-bodies, stress granules, and neuronal and germinal granules, as well as nuclear paraspeckles, Cajal bodies, and RNA foci formed from repeat expansion RNAs. Recent evidence argues that intermolecular RNA-RNA interactions play a role in forming and determining the composition of certain RNP granules. We hypothesize that intermolecular RNA-RNA interactions are favored in cells yet are limited by RNA-binding proteins, helicases, and ribosomes, thereby allowing normal RNA function. An over-abundance of intermolecular RNA-RNA interactions may be toxic since perturbations that increase RNA-RNA interactions such as long repeat expansion RNAs, arginine-containing dipeptide repeat polypeptides, and sequestration or loss of abundant RNA-binding proteins can contribute to degenerative diseases.
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Affiliation(s)
- Briana Van Treeck
- Department of Biochemistry, University of Colorado, Boulder, CO 80309, USA
| | - Roy Parker
- Department of Biochemistry, University of Colorado, Boulder, CO 80309, USA; Howard Hughes Medical Institute, University of Colorado, Boulder, CO 80309, USA.
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22
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Holzer K, Ori A, Cooke A, Dauch D, Drucker E, Riemenschneider P, Andres-Pons A, DiGuilio AL, Mackmull MT, Baßler J, Roessler S, Breuhahn K, Zender L, Glavy JS, Dombrowski F, Hurt E, Schirmacher P, Beck M, Singer S. Nucleoporin Nup155 is part of the p53 network in liver cancer. Nat Commun 2019; 10:2147. [PMID: 31089132 DOI: 10.1038/s41467-019-10133-z] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2018] [Accepted: 04/16/2019] [Indexed: 02/08/2023] Open
Abstract
Cancer-relevant signalling pathways rely on bidirectional nucleocytoplasmic transport events through the nuclear pore complex (NPC). However, mechanisms by which individual NPC components (Nups) participate in the regulation of these pathways remain poorly understood. We discover by integrating large scale proteomics, polysome fractionation and a focused RNAi approach that Nup155 controls mRNA translation of p21 (CDKN1A), a key mediator of the p53 response. The underlying mechanism involves transcriptional regulation of the putative tRNA and rRNA methyltransferase FTSJ1 by Nup155. Furthermore, we observe that Nup155 and FTSJ1 are p53 repression targets and accordingly find a correlation between the p53 status, Nup155 and FTSJ1 expression in murine and human hepatocellular carcinoma. Our data suggest an unanticipated regulatory network linking translational control by and repression of a structural NPC component modulating the p53 pathway through its effectors. The nuclear pore complex (NPC) is known to regulate p53 signaling and this has mainly been linked to peripheral NPC subunits. Here the authors show that Nup155 from the NPC inner ring regulates the p53 pathway by controlling p21 translation while also being a target of p53-mediated repression.
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23
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Abstract
Nuclear pore complexes (NPCs) mediate nucleocytoplasmic exchange. They are exceptionally large protein complexes that fuse the inner and outer nuclear membranes to form channels across the nuclear envelope. About 30 different protein components, termed nucleoporins, assemble in multiple copies into an intricate cylindrical architecture. Here, we review our current knowledge of the structure of nucleoporins and how those come together in situ. We delineate architectural principles on several hierarchical organization levels, including isoforms, posttranslational modifications, nucleoporins, and higher-order oligomerization of nucleoporin subcomplexes. We discuss how cells exploit this modularity to faithfully assemble NPCs.
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Affiliation(s)
- Bernhard Hampoelz
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany; , ,
| | - Amparo Andres-Pons
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany; , , .,Current affiliation: Friedrich Miescher Institute for Biomedical Research, 4058 Basel, Switzerland;
| | - Panagiotis Kastritis
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany; , , .,Current affiliation: ZIK HALOmem, Martin Luther University of Halle-Wittenberg, 06120 Halle (Saale), Germany
| | - Martin Beck
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany; , , .,Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany.,Max Planck Institute of Biophysics, 60438 Frankfurt am Main, Germany
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24
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Cho KI, Yoon D, Yu M, Peachey NS, Ferreira PA. Microglial activation in an amyotrophic lateral sclerosis-like model caused by Ranbp2 loss and nucleocytoplasmic transport impairment in retinal ganglion neurons. Cell Mol Life Sci 2019; 76:3407-3432. [PMID: 30944974 DOI: 10.1007/s00018-019-03078-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [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: 12/20/2018] [Revised: 02/21/2019] [Accepted: 03/18/2019] [Indexed: 12/12/2022]
Abstract
Nucleocytoplasmic transport is dysregulated in sporadic and familial amyotrophic lateral sclerosis (ALS) and retinal ganglion neurons (RGNs) are purportedly involved in ALS. The Ran-binding protein 2 (Ranbp2) controls rate-limiting steps of nucleocytoplasmic transport. Mice with Ranbp2 loss in Thy1+-motoneurons develop cardinal ALS-like motor traits, but the impairments in RGNs and the degree of dysfunctional consonance between RGNs and motoneurons caused by Ranbp2 loss are unknown. This will help to understand the role of nucleocytoplasmic transport in the differential vulnerability of neuronal cell types to ALS and to uncover non-motor endophenotypes with pathognomonic signs of ALS. Here, we ascertain Ranbp2's function and endophenotypes in RGNs of an ALS-like mouse model lacking Ranbp2 in motoneurons and RGNs. Thy1+-RGNs lacking Ranbp2 shared with motoneurons the dysregulation of nucleocytoplasmic transport. RGN abnormalities were comprised morphologically by soma hypertrophy and optic nerve axonopathy and physiologically by a delay of the visual pathway's evoked potentials. Whole-transcriptome analysis showed restricted transcriptional changes in optic nerves that were distinct from those found in sciatic nerves. Specifically, the level and nucleocytoplasmic partition of the anti-apoptotic and novel substrate of Ranbp2, Pttg1/securin, were dysregulated. Further, acetyl-CoA carboxylase 1, which modulates de novo synthesis of fatty acids and T-cell immunity, showed the highest up-regulation (35-fold). This effect was reflected by the activation of ramified CD11b+ and CD45+-microglia, increase of F4\80+-microglia and a shift from pseudopodial/lamellipodial to amoeboidal F4\80+-microglia intermingled between RGNs of naive mice. Further, there was the intracellular sequestration in RGNs of metalloproteinase-28, which regulates macrophage recruitment and polarization in inflammation. Hence, Ranbp2 genetic insults in RGNs and motoneurons trigger distinct paracrine signaling likely by the dysregulation of nucleocytoplasmic transport of neuronal-type selective substrates. Immune-modulators underpinning RGN-to-microglial signaling are regulated by Ranbp2, and this neuronal-glial system manifests endophenotypes that are likely useful in the prognosis and diagnosis of motoneuron diseases, such as ALS.
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Affiliation(s)
- Kyoung-In Cho
- Department of Ophthalmology, Duke University Medical Center, DUEC 3802, 2351 Erwin Road, Durham, NC, 27710, USA
| | - Dosuk Yoon
- Department of Ophthalmology, Duke University Medical Center, DUEC 3802, 2351 Erwin Road, Durham, NC, 27710, USA
| | - Minzhong Yu
- Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic Foundation, Cleveland, OH, 44195, USA.,Department of Ophthalmology, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, OH, 44195, USA
| | - Neal S Peachey
- Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic Foundation, Cleveland, OH, 44195, USA.,Research Service, Louis Stokes Cleveland Veterans Affairs Medical Center, Cleveland, OH, 44106, USA.,Department of Ophthalmology, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, OH, 44195, USA
| | - Paulo A Ferreira
- Department of Ophthalmology, Duke University Medical Center, DUEC 3802, 2351 Erwin Road, Durham, NC, 27710, USA.
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25
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Abstract
The nuclear pore complex (NPC) serves as the sole bidirectional gateway of macromolecules in and out of the nucleus. Owing to its size and complexity (∼1,000 protein subunits, ∼110 MDa in humans), the NPC has remained one of the foremost challenges for structure determination. Structural studies have now provided atomic-resolution crystal structures of most nucleoporins. The acquisition of these structures, combined with biochemical reconstitution experiments, cross-linking mass spectrometry, and cryo-electron tomography, has facilitated the determination of the near-atomic overall architecture of the symmetric core of the human, fungal, and algal NPCs. Here, we discuss the insights gained from these new advances and outstanding issues regarding NPC structure and function. The powerful combination of bottom-up and top-down approaches toward determining the structure of the NPC offers a paradigm for uncovering the architectures of other complex biological machines to near-atomic resolution.
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Affiliation(s)
- Daniel H Lin
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, USA;
| | - André Hoelz
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, USA;
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26
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Ferreira PA. The coming-of-age of nucleocytoplasmic transport in motor neuron disease and neurodegeneration. Cell Mol Life Sci 2019; 76:2247-2273. [PMID: 30742233 DOI: 10.1007/s00018-019-03029-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [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: 12/21/2018] [Accepted: 01/28/2019] [Indexed: 12/11/2022]
Abstract
The nuclear pore is the gatekeeper of nucleocytoplasmic transport and signaling through which a vast flux of information is continuously exchanged between the nuclear and cytoplasmic compartments to maintain cellular homeostasis. A unifying and organizing principle has recently emerged that cements the notion that several forms of amyotrophic lateral sclerosis (ALS), and growing number of other neurodegenerative diseases, co-opt the dysregulation of nucleocytoplasmic transport and that this impairment is a pathogenic driver of neurodegeneration. The understanding of shared pathomechanisms that underpin neurodegenerative diseases with impairments in nucleocytoplasmic transport and how these interface with current concepts of nucleocytoplasmic transport is bound to illuminate this fundamental biological process in a yet more physiological context. Here, I summarize unresolved questions and evidence and extend basic and critical concepts and challenges of nucleocytoplasmic transport and its role in the pathogenesis of neurodegenerative diseases, such as ALS. These principles will help to appreciate the roles of nucleocytoplasmic transport in the pathogenesis of ALS and other neurodegenerative diseases, and generate a framework for new ideas of the susceptibility of motoneurons, and possibly other neurons, to degeneration by dysregulation of nucleocytoplasmic transport.
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Affiliation(s)
- Paulo A Ferreira
- Duke University Medical Center, DUEC 3802, 2351 Erwin Road, Durham, NC, 27710, USA.
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27
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Abstract
Dynein adaptor proteins such as Bicaudal D2 (BicD2) are integral components of the dynein transport machinery, as they recognize cargoes for cell cycle-specific transport and link them to the motor complex. Human BicD2 switches from selecting secretory and Golgi-derived vesicles for transport in G1 and S phase (by recognizing Rab6GTP), to selecting the nucleus for transport in G2 phase (by recognizing nuclear pore protein Nup358), but the molecular mechanisms governing this switch are elusive. Here, we have developed a quantitative model for BicD2/cargo interactions that integrates affinities, oligomeric states, and cellular concentrations of the reactants. BicD2 and cargo form predominantly 2:2 complexes. Furthermore, the affinity of BicD2 toward its cargo Nup358 is higher than that toward Rab6GTP. Based on our calculations, an estimated 1000 BicD2 molecules per cell would be recruited to the nucleus through Nup358 in the absence of regulation. Notably, RanGTP is a negative regulator of the Nup358/BicD2 interaction that weakens the affinity by a factor of 10 and may play a role in averting dynein recruitment to the nucleus outside of the G2 phase. However, our quantitative model predicts that an additional negative regulator remains to be identified. In the absence of negative regulation, the affinity of Nup358 would likely be sufficient to recruit BicD2 to the nucleus in G2 phase. Our quantitative model makes testable predictions of how cellular transport events are orchestrated. These transport processes are important for brain development, cell cycle control, signaling, and neurotransmission at synapses.
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Affiliation(s)
- Crystal R Noell
- Department of Chemistry , State University of New York at Binghamton , Binghamton , New York 13902 , United States
| | - Kyle M Loftus
- Department of Chemistry , State University of New York at Binghamton , Binghamton , New York 13902 , United States
| | - Heying Cui
- Department of Chemistry , State University of New York at Binghamton , Binghamton , New York 13902 , United States
| | - Christof Grewer
- Department of Chemistry , State University of New York at Binghamton , Binghamton , New York 13902 , United States
| | - Megan Kizer
- Department of Chemistry , State University of New York at Binghamton , Binghamton , New York 13902 , United States
| | - Erik W Debler
- Department of Biochemistry & Molecular Biology , Thomas Jefferson University , Philadelphia , Pennsylvania 19107 , United States
| | - Sozanne R Solmaz
- Department of Chemistry , State University of New York at Binghamton , Binghamton , New York 13902 , United States
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28
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De La Cruz-Herrera CF, Shire K, Siddiqi UZ, Frappier L. A genome-wide screen of Epstein-Barr virus proteins that modulate host SUMOylation identifies a SUMO E3 ligase conserved in herpesviruses. PLoS Pathog 2018; 14:e1007176. [PMID: 29979787 PMCID: PMC6051671 DOI: 10.1371/journal.ppat.1007176] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Revised: 07/18/2018] [Accepted: 06/22/2018] [Indexed: 12/30/2022] Open
Abstract
Many cellular processes pertinent for viral infection are regulated by the addition of small ubiquitin-like modifiers (SUMO) to key regulatory proteins, making SUMOylation an important mechanism by which viruses can commandeer cellular pathways. Epstein-Barr virus (EBV) is a master at manipulating of cellular processes, which enables life-long infection but can also lead to the induction of a variety of EBV-associated cancers. To identify new mechanisms by which EBV proteins alter cells, we screened a library of 51 EBV proteins for global effects on cellular SUMO1 and SUMO2 modifications (SUMOylation), identifying several proteins not previously known to manipulate this pathway. One EBV protein (BRLF1) globally induced the loss of SUMOylated proteins, in a proteasome-dependent manner, as well as the loss of promeylocytic leukemia nuclear bodies. However, unlike its homologue (Rta) in Kaposi's sarcoma associated herpesvirus, it did not appear to have ubiquitin ligase activity. In addition we identified the EBV SM protein as globally upregulating SUMOylation and showed that this activity was conserved in its homologues in herpes simplex virus 1 (HSV1 UL54/ICP27) and cytomegalovirus (CMV UL69). All three viral homologues were shown to bind SUMO and Ubc9 and to have E3 SUMO ligase activity in a purified system. These are the first SUMO E3 ligases discovered for EBV, HSV1 and CMV. Interestingly the homologues had different specificities for SUMO1 and SUMO2, with SM and UL69 preferentially binding SUMO1 and inducing SUMO1 modifications, and UL54 preferentially binding SUMO2 and inducing SUMO2 modifications. The results provide new insights into the function of this family of conserved herpesvirus proteins, and the conservation of this SUMO E3 ligase activity across diverse herpesviruses suggests the importance of this activity for herpesvirus infections.
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Affiliation(s)
| | - Kathy Shire
- Department of Molecular Genetics, University of Toronto, Toronto, Canada
| | - Umama Z. Siddiqi
- Department of Molecular Genetics, University of Toronto, Toronto, Canada
| | - Lori Frappier
- Department of Molecular Genetics, University of Toronto, Toronto, Canada
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29
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Odeh HM, Coyaud E, Raught B, Matunis MJ. The SUMO-specific isopeptidase SENP2 is targeted to intracellular membranes via a predicted N-terminal amphipathic α-helix. Mol Biol Cell 2018; 29:1878-1890. [PMID: 29874116 PMCID: PMC6085828 DOI: 10.1091/mbc.e17-07-0445] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [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] [Indexed: 11/11/2022] Open
Abstract
Sumoylation regulates a wide range of essential cellular functions, many of which are associated with activities in the nucleus. Although there is also emerging evidence for the involvement of the small ubiquitin-related modifier (SUMO) at intracellular membranes, the mechanisms by which sumoylation is regulated at membranes is largely unexplored. In this study, we report that the SUMO-specific isopeptidase, SENP2, uniquely associates with intracellular membranes. Using in vivo analyses and in vitro binding assays, we show that SENP2 is targeted to intracellular membranes via a predicted N-terminal amphipathic α-helix that promotes direct membrane binding. Furthermore, we demonstrate that SENP2 binding to intracellular membranes is regulated by interactions with the nuclear import receptor karyopherin-α. Consistent with membrane association, biotin identification (BioID) revealed interactions between SENP2 and endoplasmic reticulum, Golgi, and inner nuclear membrane-associated proteins. Collectively, our findings indicate that SENP2 binds to intracellular membranes where it interacts with membrane-associated proteins and has the potential to regulate their sumoylation and membrane-associated functions.
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Affiliation(s)
- Hana M Odeh
- Department of Biochemistry and Molecular Biology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD 21205
| | - Etienne Coyaud
- Princess Margaret Cancer Centre, University Health Network, Toronto, ON M5G 2C4, Canada
| | - Brian Raught
- Princess Margaret Cancer Centre, University Health Network, Toronto, ON M5G 2C4, Canada.,Department of Medical Biophysics, University of Toronto, Toronto, ON M5G 1L7, Canada
| | - Michael J Matunis
- Department of Biochemistry and Molecular Biology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD 21205
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30
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Van Treeck B, Protter DSW, Matheny T, Khong A, Link CD, Parker R. RNA self-assembly contributes to stress granule formation and defining the stress granule transcriptome. Proc Natl Acad Sci U S A 2018; 115:2734-9. [PMID: 29483269 DOI: 10.1073/pnas.1800038115] [Citation(s) in RCA: 292] [Impact Index Per Article: 48.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Stress granules are higher order assemblies of nontranslating mRNAs and proteins that form when translation initiation is inhibited. Stress granules are thought to form by protein-protein interactions of RNA-binding proteins. We demonstrate RNA homopolymers or purified cellular RNA forms assemblies in vitro analogous to stress granules. Remarkably, under conditions representative of an intracellular stress response, the mRNAs enriched in assemblies from total yeast RNA largely recapitulate the stress granule transcriptome. We suggest stress granules are formed by a summation of protein-protein and RNA-RNA interactions, with RNA self-assembly likely to contribute to other RNP assemblies wherever there is a high local concentration of RNA. RNA assembly in vitro is also increased by GR and PR dipeptide repeats, which are known to increase stress granule formation in cells. Since GR and PR dipeptides are involved in neurodegenerative diseases, this suggests that perturbations increasing RNA-RNA assembly in cells could lead to disease.
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31
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Mariotti M, Shetty S, Baird L, Wu S, Loughran G, Copeland PR, Atkins JF, Howard MT. Multiple RNA structures affect translation initiation and UGA redefinition efficiency during synthesis of selenoprotein P. Nucleic Acids Res 2018; 45:13004-13015. [PMID: 29069514 PMCID: PMC5727441 DOI: 10.1093/nar/gkx982] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [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: 08/22/2017] [Accepted: 10/11/2017] [Indexed: 01/03/2023] Open
Abstract
Gene-specific expansion of the genetic code allows for UGA codons to specify the amino acid selenocysteine (Sec). A striking example of UGA redefinition occurs during translation of the mRNA coding for the selenium transport protein, selenoprotein P (SELENOP), which in vertebrates may contain up to 22 in-frame UGA codons. Sec incorporation at the first and downstream UGA codons occurs with variable efficiencies to control synthesis of full-length and truncated SELENOP isoforms. To address how the Selenop mRNA can direct dynamic codon redefinition in different regions of the same mRNA, we undertook a comprehensive search for phylogenetically conserved RNA structures and examined the function of these structures using cell-based assays, in vitro translation systems, and in vivo ribosome profiling of liver tissue from mice carrying genomic deletions of 3′ UTR selenocysteine-insertion-sequences (SECIS1 and SECIS2). The data support a novel RNA structure near the start codon that impacts translation initiation, structures located adjacent to UGA codons, additional coding sequence regions necessary for efficient production of full-length SELENOP, and distinct roles for SECIS1 and SECIS2 at UGA codons. Our results uncover a remarkable diversity of RNA elements conducting multiple occurrences of UGA redefinition to control the synthesis of full-length and truncated SELENOP isoforms.
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Affiliation(s)
- Marco Mariotti
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA USA
| | - Sumangala Shetty
- Department of Biochemistry and Molecular Biology, Rutgers Robert Wood Johnson Medical School, Piscataway, NJ USA
| | - Lisa Baird
- Department of Human Genetics, University of Utah, Salt Lake City, UT, USA
| | - Sen Wu
- State Key Laboratory of Agrobiotechnology, China Agricultural University, Beijing 100193, People's Republic of China
| | - Gary Loughran
- Biochemistry and Cell Biology, University College Cork, Cork, Ireland
| | - Paul R Copeland
- Department of Biochemistry and Molecular Biology, Rutgers Robert Wood Johnson Medical School, Piscataway, NJ USA
| | - John F Atkins
- Department of Human Genetics, University of Utah, Salt Lake City, UT, USA.,Biochemistry and Cell Biology, University College Cork, Cork, Ireland
| | - Michael T Howard
- Department of Human Genetics, University of Utah, Salt Lake City, UT, USA
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32
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Lee ES, Palazzo AF. Assessing mRNA nuclear export in mammalian cells by microinjection. Methods 2017; 126:76-85. [DOI: 10.1016/j.ymeth.2017.05.027] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2017] [Revised: 05/23/2017] [Accepted: 05/29/2017] [Indexed: 11/17/2022] Open
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33
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Abstract
The nuclear envelope is tethered to the cytoskeleton. The best known attachments of all elements of the cytoskeleton are via the so-called LINC complex. However, the nuclear pore complexes, which mediate the transport of soluble and membrane bound molecules, are also linked to the microtubule network, primarily via motor proteins (dynein and kinesins) which are linked, most importantly, to the cytoplasmic filament protein of the nuclear pore complex, Nup358, by the adaptor BicD2. The evidence for such linkages and possible roles in nuclear migration, cell cycle control, nuclear transport and cell architecture are discussed.
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34
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Cenik C, Chua HN, Singh G, Akef A, Snyder MP, Palazzo AF, Moore MJ, Roth FP. A common class of transcripts with 5'-intron depletion, distinct early coding sequence features, and N1-methyladenosine modification. RNA 2017; 23:270-283. [PMID: 27994090 PMCID: PMC5311483 DOI: 10.1261/rna.059105.116] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2016] [Accepted: 12/14/2016] [Indexed: 06/01/2023]
Abstract
Introns are found in 5' untranslated regions (5'UTRs) for 35% of all human transcripts. These 5'UTR introns are not randomly distributed: Genes that encode secreted, membrane-bound and mitochondrial proteins are less likely to have them. Curiously, transcripts lacking 5'UTR introns tend to harbor specific RNA sequence elements in their early coding regions. To model and understand the connection between coding-region sequence and 5'UTR intron status, we developed a classifier that can predict 5'UTR intron status with >80% accuracy using only sequence features in the early coding region. Thus, the classifier identifies transcripts with 5' proximal-intron-minus-like-coding regions ("5IM" transcripts). Unexpectedly, we found that the early coding sequence features defining 5IM transcripts are widespread, appearing in 21% of all human RefSeq transcripts. The 5IM class of transcripts is enriched for non-AUG start codons, more extensive secondary structure both preceding the start codon and near the 5' cap, greater dependence on eIF4E for translation, and association with ER-proximal ribosomes. 5IM transcripts are bound by the exon junction complex (EJC) at noncanonical 5' proximal positions. Finally, N1-methyladenosines are specifically enriched in the early coding regions of 5IM transcripts. Taken together, our analyses point to the existence of a distinct 5IM class comprising ∼20% of human transcripts. This class is defined by depletion of 5' proximal introns, presence of specific RNA sequence features associated with low translation efficiency, N1-methyladenosines in the early coding region, and enrichment for noncanonical binding by the EJC.
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Affiliation(s)
- Can Cenik
- Department of Genetics, Stanford University School of Medicine, Stanford, California 94305, USA
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
| | - Hon Nian Chua
- Donnelly Centre, Department of Molecular Genetics, and Department of Computer Science, University of Toronto, Toronto M5S 3E1, Ontario, Canada
- Lunenfeld-Tanenbaum Research Institute, Mt. Sinai Hospital, Toronto M5G 1X5, Ontario, Canada
- DataRobot, Inc., Boston, Massachusetts 02109, USA
| | - Guramrit Singh
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
- Department of Molecular Genetics, Center for RNA Biology, The Ohio State University, Columbus, Ohio 43210, USA
- Howard Hughes Medical Institute, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
- RNA Therapeutics Institute, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
| | - Abdalla Akef
- Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Michael P Snyder
- Department of Genetics, Stanford University School of Medicine, Stanford, California 94305, USA
| | - Alexander F Palazzo
- Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Melissa J Moore
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
- Howard Hughes Medical Institute, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
- RNA Therapeutics Institute, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
| | - Frederick P Roth
- Donnelly Centre, Department of Molecular Genetics, and Department of Computer Science, University of Toronto, Toronto M5S 3E1, Ontario, Canada
- Lunenfeld-Tanenbaum Research Institute, Mt. Sinai Hospital, Toronto M5G 1X5, Ontario, Canada
- Center for Cancer Systems Biology (CCSB), Dana-Farber Cancer Institute, Boston 02215, Massachusetts, USA
- The Canadian Institute for Advanced Research, Toronto M5G 1Z8, Ontario, Canada
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35
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Cho KI, Yoon D, Qiu S, Danziger Z, Grill WM, Wetsel WC, Ferreira PA. Loss of Ranbp2 in motoneurons causes disruption of nucleocytoplasmic and chemokine signaling, proteostasis of hnRNPH3 and Mmp28, and development of amyotrophic lateral sclerosis-like syndromes. Dis Model Mech 2017; 10:559-579. [PMID: 28100513 PMCID: PMC5451164 DOI: 10.1242/dmm.027730] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [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: 09/08/2016] [Accepted: 12/12/2016] [Indexed: 12/12/2022] Open
Abstract
The pathogenic drivers of sporadic and familial motor neuron disease (MND), such amyotrophic lateral sclerosis (ALS), are unknown. MND impairs the Ran GTPase cycle, which controls nucleocytoplasmic transport, ribostasis and proteostasis; however, cause-effect mechanisms of Ran GTPase modulators in motoneuron pathobiology have remained elusive. The cytosolic and peripheral nucleoporin Ranbp2 is a crucial regulator of the Ran GTPase cycle and of the proteostasis of neurological disease-prone substrates, but the roles of Ranbp2 in motoneuron biology and disease remain unknown. This study shows that conditional ablation of Ranbp2 in mouse Thy1 motoneurons causes ALS syndromes with hypoactivity followed by hindlimb paralysis, respiratory distress and, ultimately, death. These phenotypes are accompanied by: a decline in the nerve conduction velocity, free fatty acids and phophatidylcholine of the sciatic nerve; a reduction in the g-ratios of sciatic and phrenic nerves; and hypertrophy of motoneurons. Furthermore, Ranbp2 loss disrupts the nucleocytoplasmic partitioning of the import and export nuclear receptors importin β and exportin 1, respectively, Ran GTPase and histone deacetylase 4. Whole-transcriptome, proteomic and cellular analyses uncovered that the chemokine receptor Cxcr4, its antagonizing ligands Cxcl12 and Cxcl14, and effector, latent and activated Stat3 all undergo early autocrine and proteostatic deregulation, and intracellular sequestration and aggregation as a result of Ranbp2 loss in motoneurons. These effects were accompanied by paracrine and autocrine neuroglial deregulation of hnRNPH3 proteostasis in sciatic nerve and motoneurons, respectively, and post-transcriptional downregulation of metalloproteinase 28 in the sciatic nerve. Mechanistically, our results demonstrate that Ranbp2 controls nucleocytoplasmic, chemokine and metalloproteinase 28 signaling, and proteostasis of substrates that are crucial to motoneuronal homeostasis and whose impairments by loss of Ranbp2 drive ALS-like syndromes. Summary: Loss of Ranbp2 in spinal motoneurons drives ALS syndromes in mice and Ranbp2 functions in nucleocytoplasmic trafficking, proteostasis and chemokine signaling uncover novel therapeutic targets and mechanisms for motoneuron disease.
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Affiliation(s)
- Kyoung-In Cho
- Department of Ophthalmology, Duke University Medical Center, Durham, NC 27710, USA
| | - Dosuk Yoon
- Department of Ophthalmology, Duke University Medical Center, Durham, NC 27710, USA
| | - Sunny Qiu
- Department of Ophthalmology, Duke University Medical Center, Durham, NC 27710, USA
| | - Zachary Danziger
- Department of Biomedical Engineering, Duke University, Durham, NC 27710, USA
| | - Warren M Grill
- Department of Biomedical Engineering, Duke University, Durham, NC 27710, USA
| | - William C Wetsel
- Departments of Psychiatry and Behavioral Sciences, Cell Biology, and Neurobiology, Mouse Behavioral and Neuroendocrine Analysis Core Facility, Duke University Medical Center, Durham, NC 27710, USA
| | - Paulo A Ferreira
- Department of Ophthalmology, Duke University Medical Center, Durham, NC 27710, USA .,Department of Pathology, Duke University Medical Center, Durham, NC 27710, USA
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Sahoo MR, Gaikwad S, Khuperkar D, Ashok M, Helen M, Yadav SK, Singh A, Magre I, Deshmukh P, Dhanvijay S, Sahoo PK, Ramtirtha Y, Madhusudhan MS, Gayathri P, Seshadri V, Joseph J. Nup358 binds to AGO proteins through its SUMO-interacting motifs and promotes the association of target mRNA with miRISC. EMBO Rep 2016; 18:241-263. [PMID: 28039207 DOI: 10.15252/embr.201642386] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [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: 03/15/2016] [Revised: 11/13/2016] [Accepted: 11/24/2016] [Indexed: 11/09/2022] Open
Abstract
MicroRNA (miRNA)-guided mRNA repression, mediated by the miRNA-induced silencing complex (miRISC), is an important component of post-transcriptional gene silencing. However, how miRISC identifies the target mRNA in vivo is not well understood. Here, we show that the nucleoporin Nup358 plays an important role in this process. Nup358 localizes to the nuclear pore complex and to the cytoplasmic annulate lamellae (AL), and these structures dynamically associate with two mRNP granules: processing bodies (P bodies) and stress granules (SGs). Nup358 depletion disrupts P bodies and concomitantly impairs the miRNA pathway. Furthermore, Nup358 interacts with AGO and GW182 proteins and promotes the association of target mRNA with miRISC A well-characterized SUMO-interacting motif (SIM) in Nup358 is sufficient for Nup358 to directly bind to AGO proteins. Moreover, AGO and PIWI proteins interact with SIMs derived from other SUMO-binding proteins. Our study indicates that Nup358-AGO interaction is important for miRNA-mediated gene silencing and identifies SIM as a new interacting motif for the AGO family of proteins. The findings also support a model wherein the coupling of miRISC with the target mRNA could occur at AL, specialized domains within the ER, and at the nuclear envelope.
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Affiliation(s)
- Manas Ranjan Sahoo
- National Centre for Cell Science, S.P. Pune University Campus, Pune, India
| | - Swati Gaikwad
- National Centre for Cell Science, S.P. Pune University Campus, Pune, India
| | - Deepak Khuperkar
- National Centre for Cell Science, S.P. Pune University Campus, Pune, India
| | - Maitreyi Ashok
- National Centre for Cell Science, S.P. Pune University Campus, Pune, India
| | - Mary Helen
- National Centre for Cell Science, S.P. Pune University Campus, Pune, India
| | | | - Aditi Singh
- National Centre for Cell Science, S.P. Pune University Campus, Pune, India
| | - Indrasen Magre
- National Centre for Cell Science, S.P. Pune University Campus, Pune, India
| | - Prachi Deshmukh
- National Centre for Cell Science, S.P. Pune University Campus, Pune, India
| | - Supriya Dhanvijay
- National Centre for Cell Science, S.P. Pune University Campus, Pune, India
| | | | - Yogendra Ramtirtha
- Division of Biology, Indian Institute of Science Education and Research, Pune, India
| | | | - Pananghat Gayathri
- Division of Biology, Indian Institute of Science Education and Research, Pune, India
| | - Vasudevan Seshadri
- National Centre for Cell Science, S.P. Pune University Campus, Pune, India
| | - Jomon Joseph
- National Centre for Cell Science, S.P. Pune University Campus, Pune, India
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Liao Y, Castello A, Fischer B, Leicht S, Föehr S, Frese CK, Ragan C, Kurscheid S, Pagler E, Yang H, Krijgsveld J, Hentze MW, Preiss T. The Cardiomyocyte RNA-Binding Proteome: Links to Intermediary Metabolism and Heart Disease. Cell Rep 2016; 16:1456-1469. [PMID: 27452465 PMCID: PMC4977271 DOI: 10.1016/j.celrep.2016.06.084] [Citation(s) in RCA: 97] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2015] [Revised: 04/06/2016] [Accepted: 06/07/2016] [Indexed: 11/30/2022] Open
Abstract
RNA functions through the dynamic formation of complexes with RNA-binding proteins (RBPs) in all clades of life. We determined the RBP repertoire of beating cardiomyocytic HL-1 cells by jointly employing two in vivo proteomic methods, mRNA interactome capture and RBDmap. Together, these yielded 1,148 RBPs, 391 of which are shared with all other available mammalian RBP repertoires, while 393 are thus far unique to cardiomyocytes. RBDmap further identified 568 regions of RNA contact within 368 RBPs. The cardiomyocyte mRNA interactome composition reflects their unique biology. Proteins with roles in cardiovascular physiology or disease, mitochondrial function, and intermediary metabolism are all highly represented. Notably, we identified 73 metabolic enzymes as RBPs. RNA-enzyme contacts frequently involve Rossmann fold domains with examples in evidence of both, mutual exclusivity of, or compatibility between RNA binding and enzymatic function. Our findings raise the prospect of previously hidden RNA-mediated regulatory interactions among cardiomyocyte gene expression, physiology, and metabolism. mRNA interactome capture and RBDmap reveal the cardiomyocyte RNA-binding proteome 1,148 RBPs are identified, 393 of which are thus far unique to cardiomyocytes Many cardiac RBPs have links to heart disease and mitochondrial metabolism Contacts of metabolic enzymes with RNA frequently involve Rossmann fold domains
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Affiliation(s)
- Yalin Liao
- EMBL-Australia Collaborating Group, Department of Genome Sciences, The John Curtin School of Medical Research (JCSMR), The Australian National University, Acton (Canberra) ACT 2601, Australia
| | - Alfredo Castello
- European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany
| | - Bernd Fischer
- European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany
| | - Stefan Leicht
- European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany
| | - Sophia Föehr
- European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany
| | - Christian K Frese
- European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany
| | - Chikako Ragan
- EMBL-Australia Collaborating Group, Department of Genome Sciences, The John Curtin School of Medical Research (JCSMR), The Australian National University, Acton (Canberra) ACT 2601, Australia
| | - Sebastian Kurscheid
- EMBL-Australia Collaborating Group, Department of Genome Sciences, The John Curtin School of Medical Research (JCSMR), The Australian National University, Acton (Canberra) ACT 2601, Australia
| | - Eloisa Pagler
- EMBL-Australia Collaborating Group, Department of Genome Sciences, The John Curtin School of Medical Research (JCSMR), The Australian National University, Acton (Canberra) ACT 2601, Australia
| | - Hao Yang
- EMBL-Australia Collaborating Group, Department of Genome Sciences, The John Curtin School of Medical Research (JCSMR), The Australian National University, Acton (Canberra) ACT 2601, Australia
| | - Jeroen Krijgsveld
- European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany
| | - Matthias W Hentze
- European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany
| | - Thomas Preiss
- EMBL-Australia Collaborating Group, Department of Genome Sciences, The John Curtin School of Medical Research (JCSMR), The Australian National University, Acton (Canberra) ACT 2601, Australia; Victor Chang Cardiac Research Institute, Darlinghurst (Sydney), NSW 2010, Australia.
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Affiliation(s)
| | - Mathew Truong
- Department of Biochemistry; University of Toronto; Toronto ON Canada
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39
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Abstract
In eukaryotes, mRNAs are synthesized in the nucleus and then exported to the cytoplasm where they are translated into proteins. We have mapped an element, which when present in the 3’terminal exon or in an unspliced mRNA, inhibits mRNA nuclear export. This element has the same sequence as the consensus 5’splice site motif that is used to define the start of introns. Previously it was shown that when this motif is retained in the mRNA, it causes defects in 3’cleavage and polyadenylation and promotes mRNA decay. Our new data indicates that this motif also inhibits nuclear export and promotes the targeting of transcripts to nuclear speckles, foci within the nucleus which have been linked to splicing. The motif, however, does not disrupt splicing or the recruitment of UAP56 or TAP/Nxf1 to the RNA, which are normally required for nuclear export. Genome wide analysis of human mRNAs, lncRNA and eRNAs indicates that this motif is depleted from naturally intronless mRNAs and eRNAs, but less so in lncRNAs. This motif is also depleted from the beginning and ends of the 3’terminal exons of spliced mRNAs, but less so for lncRNAs. Our data suggests that the presence of the 5’splice site motif in mature RNAs promotes their nuclear retention and may help to distinguish mRNAs from misprocessed transcripts and transcriptional noise.
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Affiliation(s)
- Eliza S. Lee
- Department of Biochemistry, University of Toronto, 1 King’s College Circle, MSB Room 5336, Toronto, ON, M5S 1A8, Canada
| | - Abdalla Akef
- Department of Biochemistry, University of Toronto, 1 King’s College Circle, MSB Room 5336, Toronto, ON, M5S 1A8, Canada
| | - Kohila Mahadevan
- Department of Biochemistry, University of Toronto, 1 King’s College Circle, MSB Room 5336, Toronto, ON, M5S 1A8, Canada
| | - Alexander F. Palazzo
- Department of Biochemistry, University of Toronto, 1 King’s College Circle, MSB Room 5336, Toronto, ON, M5S 1A8, Canada
- * E-mail:
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Zhang H, Mahadevan K, Palazzo AF. Sumoylation is Required for the Cytoplasmic Accumulation of a Subset of mRNAs. Genes (Basel) 2014; 5:982-1000. [PMID: 25333844 DOI: 10.3390/genes5040982] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2014] [Revised: 09/26/2014] [Accepted: 10/04/2014] [Indexed: 12/17/2022] Open
Abstract
In order to discover novel proteins that promote the nuclear export of newly synthesized mRNAs in mammalian cells, we carried out a limited RNAi screen for proteins required for the proper cytoplasmic distribution of a model intronless mRNA. From this screen we obtained two hits, Ubc9 (SUMO-conjugating E2 enzyme) and GANP (germinal center-associated nuclear protein). Depletion of Ubc9 inhibited the proper cytoplasmic distribution of certain overexpressed intronless mRNAs, while depletion of GANP affected all tested mRNAs. Depletion of Sae1, which is also required for sumoylation, partially inhibited the cytoplasmic distribution of our model mRNA. Interestingly, the block in cytoplasmic accumulation in Ubc9-depleted cells could be overcome if an intron was incorporated into the mRNA. Surprisingly, Ubc9-depleted cells had normal nuclear export of newly synthesized intronless mRNAs, indicating that the observed accumulation of the model mRNA in the nuclei of transfected cells was likely due to some more general perturbation. Indeed, depletion of Ubc9, coupled with the overexpression of the intronless mRNAs, caused the redistribution of the nuclear speckle protein SC35 to cytoplasmic foci. Our results suggest that sumoylation may play a role in the proper assembly of mRNPs and/or the distribution of key RNA binding proteins, and may thus contribute to general protein expression patterns.
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Kelich JM, Yang W. High-resolution imaging reveals new features of nuclear export of mRNA through the nuclear pore complexes. Int J Mol Sci 2014; 15:14492-504. [PMID: 25141104 PMCID: PMC4159864 DOI: 10.3390/ijms150814492] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2014] [Revised: 08/08/2014] [Accepted: 08/15/2014] [Indexed: 12/20/2022] Open
Abstract
The nuclear envelope (NE) of eukaryotic cells provides a physical barrier for messenger RNA (mRNA) and the associated proteins (mRNPs) traveling from sites of transcription in the nucleus to locations of translation processing in the cytoplasm. Nuclear pore complexes (NPCs) embedded in the NE serve as a dominant gateway for nuclear export of mRNA. However, the fundamental characterization of export dynamics of mRNPs through the NPC has been hindered by several technical limits. First, the size of NPC that is barely below the diffraction limit of conventional light microscopy requires a super-resolution microscopy imaging approach. Next, the fast transit of mRNPs through the NPC further demands a high temporal resolution by the imaging approach. Finally, the inherent three-dimensional (3D) movements of mRNPs through the NPC demand the method to provide a 3D mapping of both transport kinetics and transport pathways of mRNPs. This review will highlight the recently developed super-resolution imaging techniques advanced from 1D to 3D for nuclear export of mRNPs and summarize the new features in the dynamic nuclear export process of mRNPs revealed from these technical advances.
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Affiliation(s)
- Joseph M Kelich
- Department of Biology, Temple University, Philadelphia, PA 19122, USA.
| | - Weidong Yang
- Department of Biology, Temple University, Philadelphia, PA 19122, USA.
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Abstract
Nuclear pore complexes (NPCs) are the sole gateways between the nucleus and the cytoplasm of eukaryotic cells and they mediate all macromolecular trafficking between these cellular compartments. Nucleocytoplasmic transport is highly selective and precisely regulated and as such an important aspect of normal cellular function. Defects in this process or in its machinery have been linked to various human diseases, including cancer. Nucleoporins, which are about 30 proteins that built up NPCs, are critical players in nucleocytoplasmic transport and have also been shown to be key players in numerous other cellular processes, such as cell cycle control and gene expression regulation. This review will focus on the three nucleoporins Nup98, Nup214, and Nup358. Common to them is their significance in nucleocytoplasmic transport, their multiple other functions, and being targets for chromosomal translocations that lead to haematopoietic malignancies, in particular acute myeloid leukaemia. The underlying molecular mechanisms of nucleoporin-associated leukaemias are only poorly understood but share some characteristics and are distinguished by their poor prognosis and therapy outcome.
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Cui XA, Palazzo AF. Localization of mRNAs to the endoplasmic reticulum. Wiley Interdiscip Rev RNA 2014; 5:481-92. [PMID: 24644132 DOI: 10.1002/wrna.1225] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2013] [Revised: 02/10/2014] [Accepted: 02/11/2014] [Indexed: 12/17/2022]
Abstract
Almost all cells use mRNA localization to establish spatial control of protein synthesis. One of the best-studied examples is the targeting and anchoring of mRNAs encoding secreted, organellar, and membrane-bound proteins to the surface of the endoplasmic reticulum (ER). In this review, we provide a historical perspective on the research that elucidated the canonical protein-mediated targeting of nascent-chain ribosome mRNA complexes to the surface of the ER. We then discuss subsequent studies which provided concrete evidence that a subpopulation of mRNAs utilize a translation-independent mechanism to localize to the surface of this organelle. This alternative mechanism operates alongside the signal recognition particle (SRP) mediated co-translational targeting pathway to promote proper mRNA localization to the ER. Recent work has uncovered trans-acting factors, such as the mRNA receptor p180, and cis-acting elements, such as transmembrane domain coding regions, that are responsible for this alternative mRNA localization process. Furthermore, some unanticipated observations have raised the possibility that this alternative pathway may be conserved from bacteria to mammalian cells.
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Affiliation(s)
- Xianying A Cui
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
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Cho KI, Patil H, Senda E, Wang J, Yi H, Qiu S, Yoon D, Yu M, Orry A, Peachey NS, Ferreira PA. Differential loss of prolyl isomerase or chaperone activity of Ran-binding protein 2 (Ranbp2) unveils distinct physiological roles of its cyclophilin domain in proteostasis. J Biol Chem 2014; 289:4600-25. [PMID: 24403063 DOI: 10.1074/jbc.m113.538215] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The immunophilins, cyclophilins, catalyze peptidyl cis-trans prolyl-isomerization (PPIase), a rate-limiting step in protein folding and a conformational switch in protein function. Cyclophilins are also chaperones. Noncatalytic mutations affecting the only cyclophilins with known but distinct physiological substrates, the Drosophila NinaA and its mammalian homolog, cyclophilin-B, impair opsin biogenesis and cause osteogenesis imperfecta, respectively. However, the physiological roles and substrates of most cyclophilins remain unknown. It is also unclear if PPIase and chaperone activities reflect distinct cyclophilin properties. To elucidate the physiological idiosyncrasy stemming from potential cyclophilin functions, we generated mice lacking endogenous Ran-binding protein-2 (Ranbp2) and expressing bacterial artificial chromosomes of Ranbp2 with impaired C-terminal chaperone and with (Tg-Ranbp2(WT-HA)) or without PPIase activities (Tg-Ranbp2(R2944A-HA)). The transgenic lines exhibit unique effects in proteostasis. Either line presents selective deficits in M-opsin biogenesis with its accumulation and aggregation in cone photoreceptors but without proteostatic impairment of two novel Ranbp2 cyclophilin partners, the cytokine-responsive effectors, STAT3/STAT5. Stress-induced STAT3 activation is also unaffected in Tg-Ranbp2(R2944A-HA)::Ranbp2(-/-). Conversely, proteomic analyses found that the multisystem proteinopathy/amyotrophic lateral sclerosis proteins, heterogeneous nuclear ribonucleoproteins A2/B1, are down-regulated post-transcriptionally only in Tg-Ranbp2(R2944A-HA)::Ranbp2(-/-). This is accompanied by the age- and tissue-dependent reductions of diubiquitin and ubiquitylated proteins, increased deubiquitylation activity, and accumulation of the 26 S proteasome subunits S1 and S5b. These manifestations are absent in another line, Tg-Ranbp2(CLDm-HA)::Ranbp2(-/-), harboring SUMO-1 and S1-binding mutations in the Ranbp2 cyclophilin-like domain. These results unveil distinct mechanistic and biological links between PPIase and chaperone activities of Ranbp2 cyclophilin toward proteostasis of selective substrates and with novel therapeutic potential.
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Affiliation(s)
- Kyoung-in Cho
- From the Departments of Ophthalmology and Pathology, Duke University Medical Center, Durham, North Carolina 27710
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Hashizume C, Kobayashi A, Wong RW. Down-modulation of nucleoporin RanBP2/Nup358 impaired chromosomal alignment and induced mitotic catastrophe. Cell Death Dis 2013; 4:e854. [PMID: 24113188 DOI: 10.1038/cddis.2013.370] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2013] [Revised: 08/22/2013] [Accepted: 08/25/2013] [Indexed: 01/03/2023]
Abstract
Chromosomal missegregation is a common feature of many human tumors. Recent studies have indicated a link between nucleoporin RanBP2/Nup358 and chromosomal segregation during mitosis; however, the molecular details have yet to be fully established. Observed through live cell imaging and flow cytometry, here we show that RNA interference-mediated knockdown of RanBP2 induced G2/M phase arrest, metaphase catastrophe and mitotic cell death. Furthermore, RanBP2 down-modulation disrupted importin/karyopherin β1 as well as the expression and localization of the Ran GTPase activating protein 1. We found that N-terminal of RanBP2 interacted with the N-terminal of importin β1. Moreover, at least a portion of RanBP2 partially localizes at the centrosome during mitosis. Notably, we also found that GTPase Ran is also involved in the regulation of RanBP2-importin β1 interaction. Overall, our results suggest that mitotic arrest and the following cell death were caused by depletion of RanBP2. Our findings point to a crucial role for RanBP2 in proper mitotic progression and faithful chromosomal segregation.
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Cui XA, Zhang Y, Hong SJ, Palazzo AF. Identification of a region within the placental alkaline phosphatase mRNA that mediates p180-dependent targeting to the endoplasmic reticulum. J Biol Chem 2013; 288:29633-41. [PMID: 24019514 DOI: 10.1074/jbc.m113.482505] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In both eukaryotic and prokaryotic cells, it has been recently established that mRNAs encoding secreted and membrane proteins can be localized to the surface of membranes via both translation-dependent and RNA element-mediated mechanisms. Previously, we showed that the placental alkaline phosphatase (ALPP) mRNA can be localized to the ER membrane independently of translation, and this localization is mediated by p180, an mRNA receptor present in the ER. In this article, we aimed to identify the cis-acting RNA element in ALPP. Using chimera constructs containing fragments of the ALPP mRNA, we demonstrate that the ER-localizing RNA element is present within the 3' end of the open reading frame and codes for a transmembrane domain. In addition, we show that this region requires p180 for efficient ER anchoring. Taken together, we provide the first insight into the nature of cis-acting ER-localizing RNA elements responsible for localizing mRNAs on the ER in mammalian cells.
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Affiliation(s)
- Xianying A Cui
- From the Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada
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Abstract
In vertebrates, the majority of mRNAs that encode secreted, membrane-bound or mitochondrial proteins contain RNA elements that activate an alternative mRNA nuclear export (ALREX) pathway. Here we demonstrate that mRNAs containing ALREX-promoting elements are trafficked through nuclear speckles. Although ALREX-promoting elements enhance nuclear speckle localization, additional features within the mRNA largely drive this process. Depletion of two TREX-associated RNA helicases, UAP56 and its paralog URH49, or inhibition of the TREX-associated nuclear transport factor, TAP, not only inhibits ALREX, but also appears to trap these mRNAs in nuclear speckles. mRNAs that contain ALREX-promoting elements associate with UAP56 in vivo. Finally, we demonstrate that mRNAs lacking a poly(A)-tail are not efficiently exported by the ALREX pathway and show enhanced association with nuclear speckles. Our data suggest that within the speckle, ALREX-promoting elements, in conjunction with the poly(A)-tail, likely stimulate UAP56/URH49 and TAP dependent steps that lead to the eventual egress of the export-competent mRNP from these structures.
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Affiliation(s)
- Abdalla Akef
- Department of Biochemistry; University of Toronto; Toronto, ON Canada; Division of Integrated Life Science; Graduate School of Biostudies; Kyoto University; Kyoto, Japan
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Palazzo AF, Mahadevan K, Tarnawsky SP. ALREX-elements and introns: two identity elements that promote mRNA nuclear export. Wiley Interdiscip Rev RNA 2013; 4:523-33. [PMID: 23913896 DOI: 10.1002/wrna.1176] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2012] [Revised: 04/24/2013] [Accepted: 04/26/2013] [Indexed: 11/09/2022]
Abstract
The mechanisms that dictate whether a particular mRNA is exported from the nucleus are still poorly defined. However, it has become increasingly clear that these mechanisms act to promote the expression of protein-coding mRNAs over the high levels of spurious transcription that is endemic to most eukaryotic genomes. For example, mRNA processing events that are associated with protein-coding transcripts, such as splicing, act as mRNA identity elements that promote nuclear export of these transcripts. Six years ago, we made the serendipitous discovery that regions within the open reading frame of an mRNA that encode short secretory or mitochondrial-targeting peptides can also act as an mRNA identity element which promotes an alternative mRNA nuclear export (ALREX) pathway. These regions are enriched in protein coding genes and have particular features that can be used to identify this class of protein-coding mRNA. In this article we review our current knowledge of how mRNA export evolved in response to particular events that occurred at the base of the eukaryotic tree. We will then focus on our current understanding of ALREX and compare its features to splicing-dependent export, the main mRNA export pathway in metazoans.
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