1
|
Sun B, Kim H, Mello CC, Priess JR. The CERV protein of Cer1, a C. elegans LTR retrotransposon, is required for nuclear export of viral genomic RNA and can form giant nuclear rods. PLoS Genet 2023; 19:e1010804. [PMID: 37384599 DOI: 10.1371/journal.pgen.1010804] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2023] [Accepted: 05/31/2023] [Indexed: 07/01/2023] Open
Abstract
Retroviruses and closely related LTR retrotransposons export full-length, unspliced genomic RNA (gRNA) for packaging into virions and to serve as the mRNA encoding GAG and POL polyproteins. Because gRNA often includes splice acceptor and donor sequences used to splice viral mRNAs, retroelements must overcome host mechanisms that retain intron-containing RNAs in the nucleus. Here we examine gRNA expression in Cer1, an LTR retrotransposon in C. elegans which somehow avoids silencing and is highly expressed in germ cells. Newly exported Cer1 gRNA associates rapidly with the Cer1 GAG protein, which has structural similarity with retroviral GAG proteins. gRNA export requires CERV (C. elegans regulator of viral expression), a novel protein encoded by a spliced Cer1 mRNA. CERV phosphorylation at S214 is essential for gRNA export, and phosphorylated CERV colocalizes with nuclear gRNA at presumptive sites of transcription. By electron microscopy, tagged CERV proteins surround clusters of distinct, linear fibrils that likely represent gRNA molecules. Single fibrils, or groups of aligned fibrils, also localize near nuclear pores. During the C. elegans self-fertile period, when hermaphrodites fertilize oocytes with their own sperm, CERV concentrates in two nuclear foci that are coincident with gRNA. However, as hermaphrodites cease self-fertilization, and can only produce cross-progeny, CERV undergoes a remarkable transition to form giant nuclear rods or cylinders that can be up to 5 microns in length. We propose a novel mechanism of rod formation, in which stage-specific changes in the nucleolus induce CERV to localize to the nucleolar periphery in flattened streaks of protein and gRNA; these streaks then roll up into cylinders. The rods are a widespread feature of Cer1 in wild strains of C. elegans, but their function is not known and might be limited to cross-progeny. We speculate that the adaptive strategy Cer1 uses for the identical self-progeny of a host hermaphrodite might differ for heterozygous cross-progeny sired by males. For example, mating introduces male chromosomes which can have different, or no, Cer1 elements.
Collapse
Affiliation(s)
- Bing Sun
- RNA Therapeutics Institute, University of Massachusetts Medical School, Worcester,United States of America
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, United States of America
- Howard Hughes Medical Institute, Chevy Chase, Maryland, United States of America
| | - Haram Kim
- Fred Hutchinson Cancer Center, Seattle, Washington, United States of America
| | - Craig C Mello
- RNA Therapeutics Institute, University of Massachusetts Medical School, Worcester,United States of America
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, United States of America
- Howard Hughes Medical Institute, Chevy Chase, Maryland, United States of America
| | - James R Priess
- Fred Hutchinson Cancer Center, Seattle, Washington, United States of America
| |
Collapse
|
2
|
Zuniga G, Levy S, Ramirez P, Mange JD, Gonzalez E, Gamez M, Frost B. Tau-induced deficits in nonsense-mediated mRNA decay contribute to neurodegeneration. Alzheimers Dement 2023; 19:405-420. [PMID: 35416419 PMCID: PMC9673995 DOI: 10.1002/alz.12653] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Revised: 01/26/2022] [Accepted: 02/17/2022] [Indexed: 12/12/2022]
Abstract
INTRODUCTION While brains of patients with Alzheimer's disease and related tauopathies have evidence of altered RNA processing, we lack a mechanistic understanding of how altered RNA processing arises in these disorders and if such changes are causally linked to neurodegeneration. METHODS Using Drosophila melanogaster models of tauopathy, we find that overall activity of nonsense-mediated mRNA decay (NMD), a key RNA quality-control mechanism, is reduced. Genetic manipulation of NMD machinery significantly modifies tau-induced neurotoxicity, suggesting that deficits in NMD are causally linked to neurodegeneration. Mechanistically, we find that deficits in NMD are a consequence of aberrant RNA export and RNA accumulation within nuclear envelope invaginations in tauopathy. We identify a pharmacological activator of NMD that suppresses neurodegeneration in tau transgenic Drosophila, indicating that tau-induced deficits in RNA quality control are druggable. DISCUSSION Our studies suggest that NMD activators should be explored for their potential therapeutic value to patients with tauopathies.
Collapse
Affiliation(s)
- Gabrielle Zuniga
- Barshop Institute for Longevity and Aging Studies, University of Texas Health San Antonio, San Antonio, Texas,Glenn Biggs Institute for Alzheimer’s and Neurodegenerative Diseases, University of Texas Health San Antonio, San Antonio, Texas,Department of Cell Systems and Anatomy, University of Texas Health San Antonio, San Antonio, Texas
| | - Simon Levy
- Barshop Institute for Longevity and Aging Studies, University of Texas Health San Antonio, San Antonio, Texas,Glenn Biggs Institute for Alzheimer’s and Neurodegenerative Diseases, University of Texas Health San Antonio, San Antonio, Texas,Department of Cell Systems and Anatomy, University of Texas Health San Antonio, San Antonio, Texas
| | - Paulino Ramirez
- Barshop Institute for Longevity and Aging Studies, University of Texas Health San Antonio, San Antonio, Texas,Glenn Biggs Institute for Alzheimer’s and Neurodegenerative Diseases, University of Texas Health San Antonio, San Antonio, Texas,Department of Cell Systems and Anatomy, University of Texas Health San Antonio, San Antonio, Texas
| | - Jasmine De Mange
- Barshop Institute for Longevity and Aging Studies, University of Texas Health San Antonio, San Antonio, Texas,Glenn Biggs Institute for Alzheimer’s and Neurodegenerative Diseases, University of Texas Health San Antonio, San Antonio, Texas,Department of Cell Systems and Anatomy, University of Texas Health San Antonio, San Antonio, Texas
| | - Elias Gonzalez
- Barshop Institute for Longevity and Aging Studies, University of Texas Health San Antonio, San Antonio, Texas,Glenn Biggs Institute for Alzheimer’s and Neurodegenerative Diseases, University of Texas Health San Antonio, San Antonio, Texas,Department of Cell Systems and Anatomy, University of Texas Health San Antonio, San Antonio, Texas
| | - Maria Gamez
- Barshop Institute for Longevity and Aging Studies, University of Texas Health San Antonio, San Antonio, Texas,Glenn Biggs Institute for Alzheimer’s and Neurodegenerative Diseases, University of Texas Health San Antonio, San Antonio, Texas,Department of Cell Systems and Anatomy, University of Texas Health San Antonio, San Antonio, Texas
| | - Bess Frost
- Barshop Institute for Longevity and Aging Studies, University of Texas Health San Antonio, San Antonio, Texas,Glenn Biggs Institute for Alzheimer’s and Neurodegenerative Diseases, University of Texas Health San Antonio, San Antonio, Texas,Department of Cell Systems and Anatomy, University of Texas Health San Antonio, San Antonio, Texas
| |
Collapse
|
3
|
Ashkenazy-Titelman A, Atrash MK, Boocholez A, Kinor N, Shav-Tal Y. RNA export through the nuclear pore complex is directional. Nat Commun 2022; 13:5881. [PMID: 36202822 PMCID: PMC9537521 DOI: 10.1038/s41467-022-33572-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Accepted: 09/22/2022] [Indexed: 11/10/2022] Open
Abstract
The changes occurring in mRNA organization during nucleo-cytoplasmic transport and export, are not well understood. Moreover, directionality of mRNA passage through the nuclear pore complex (NPC) has not been examined within individual NPCs. Here we find that an mRNP is compact during nucleoplasmic travels compared to a more open structure after transcription and at the nuclear periphery. Compaction levels of nuclear transcripts can be modulated by varying levels of SR proteins and by changing genome organization. Nuclear mRNPs are mostly rod-shaped with distant 5'/3'-ends, although for some, the ends are in proximity. The latter is more abundant in the cytoplasm and can be modified by translation inhibition. mRNAs and lncRNAs exiting the NPC exhibit predominant 5'-first export. In some cases, several adjacent NPCs are engaged in export of the same mRNA suggesting 'gene gating'. Altogether, we show that the mRNP is a flexible structure during travels, with 5'-directionality during export.
Collapse
Affiliation(s)
- Asaf Ashkenazy-Titelman
- The Mina & Everard Goodman Faculty of Life Sciences & Institute of Nanotechnology, Bar-Ilan University, Ramat Gan, 5290002, Israel
| | - Mohammad Khaled Atrash
- The Mina & Everard Goodman Faculty of Life Sciences & Institute of Nanotechnology, Bar-Ilan University, Ramat Gan, 5290002, Israel
| | - Alon Boocholez
- The Mina & Everard Goodman Faculty of Life Sciences & Institute of Nanotechnology, Bar-Ilan University, Ramat Gan, 5290002, Israel
| | - Noa Kinor
- The Mina & Everard Goodman Faculty of Life Sciences & Institute of Nanotechnology, Bar-Ilan University, Ramat Gan, 5290002, Israel
| | - Yaron Shav-Tal
- The Mina & Everard Goodman Faculty of Life Sciences & Institute of Nanotechnology, Bar-Ilan University, Ramat Gan, 5290002, Israel.
| |
Collapse
|
4
|
Into the basket and beyond: the journey of mRNA through the nuclear pore complex. Biochem J 2020; 477:23-44. [DOI: 10.1042/bcj20190132] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Revised: 11/28/2019] [Accepted: 12/10/2019] [Indexed: 02/06/2023]
Abstract
The genetic information encoded in nuclear mRNA destined to reach the cytoplasm requires the interaction of the mRNA molecule with the nuclear pore complex (NPC) for the process of mRNA export. Numerous proteins have important roles in the transport of mRNA out of the nucleus. The NPC embedded in the nuclear envelope is the port of exit for mRNA and is composed of ∼30 unique proteins, nucleoporins, forming the distinct structures of the nuclear basket, the pore channel and cytoplasmic filaments. Together, they serve as a rather stationary complex engaged in mRNA export, while a variety of soluble protein factors dynamically assemble on the mRNA and mediate the interactions of the mRNA with the NPC. mRNA export factors are recruited to and dissociate from the mRNA at the site of transcription on the gene, during the journey through the nucleoplasm and at the nuclear pore at the final stages of export. In this review, we present the current knowledge derived from biochemical, molecular, structural and imaging studies, to develop a high-resolution picture of the many events that culminate in the successful passage of the mRNA out of the nucleus.
Collapse
|
5
|
Scott DD, Aguilar LC, Kramar M, Oeffinger M. It's Not the Destination, It's the Journey: Heterogeneity in mRNA Export Mechanisms. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1203:33-81. [PMID: 31811630 DOI: 10.1007/978-3-030-31434-7_2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The process of creating a translation-competent mRNA is highly complex and involves numerous steps including transcription, splicing, addition of modifications, and, finally, export to the cytoplasm. Historically, much of the research on regulation of gene expression at the level of the mRNA has been focused on either the regulation of mRNA synthesis (transcription and splicing) or metabolism (translation and degradation). However, in recent years, the advent of new experimental techniques has revealed the export of mRNA to be a major node in the regulation of gene expression, and numerous large-scale and specific mRNA export pathways have been defined. In this chapter, we will begin by outlining the mechanism by which most mRNAs are homeostatically exported ("bulk mRNA export"), involving the recruitment of the NXF1/TAP export receptor by the Aly/REF and THOC5 components of the TREX complex. We will then examine various mechanisms by which this pathway may be controlled, modified, or bypassed in order to promote the export of subset(s) of cellular mRNAs, which include the use of metazoan-specific orthologs of bulk mRNA export factors, specific cis RNA motifs which recruit mRNA export machinery via specific trans-acting-binding factors, posttranscriptional mRNA modifications that act as "inducible" export cis elements, the use of the atypical mRNA export receptor, CRM1, and the manipulation or bypass of the nuclear pore itself. Finally, we will discuss major outstanding questions in the field of mRNA export heterogeneity and outline how cutting-edge experimental techniques are providing new insights into and tools for investigating the intriguing field of mRNA export heterogeneity.
Collapse
Affiliation(s)
- Daniel D Scott
- Institut de recherches cliniques de Montréal, Montréal, QC, Canada.,Faculty of Medicine, Division of Experimental Medicine, McGill University, Montréal, QC, Canada
| | | | - Mathew Kramar
- Institut de recherches cliniques de Montréal, Montréal, QC, Canada.,Faculty of Medicine, Division of Experimental Medicine, McGill University, Montréal, QC, Canada
| | - Marlene Oeffinger
- Institut de recherches cliniques de Montréal, Montréal, QC, Canada. .,Faculty of Medicine, Division of Experimental Medicine, McGill University, Montréal, QC, Canada. .,Faculté de Médecine, Département de Biochimie, Université de Montréal, Montréal, QC, Canada.
| |
Collapse
|
6
|
Ben-Yishay R, Mor A, Shraga A, Ashkenazy-Titelman A, Kinor N, Schwed-Gross A, Jacob A, Kozer N, Kumar P, Garini Y, Shav-Tal Y. Imaging within single NPCs reveals NXF1's role in mRNA export on the cytoplasmic side of the pore. J Cell Biol 2019; 218:2962-2981. [PMID: 31375530 PMCID: PMC6719458 DOI: 10.1083/jcb.201901127] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Revised: 06/21/2019] [Accepted: 07/03/2019] [Indexed: 12/12/2022] Open
Abstract
Translocation of mRNA through the nuclear pore complex (NPC) requires interactions with different NPC regions. To determine the interactions that are crucial for effective mRNA export in living cells, we examined mRNA export within individual pores by applying various types of mRNA export blocks that stalled mRNPs at different stages of transition. Focusing on the major mRNA export factor NXF1, we found that initial mRNP binding to the NPC did not require NXF1 in the NPC, whereas release into the cytoplasm did. NXF1 localization in the NPC did not require RNA or RNA binding. Superresolution microscopy showed that NXF1 consistently occupied positions on the cytoplasmic side of the NPC. Interactions with specific nucleoporins were pinpointed using FLIM-FRET for measuring protein-protein interactions inside single NPCs, showing that Dbp5 helicase activity of mRNA release is conserved in yeast and humans. Altogether, we find that specific interactions on the cytoplasmic side of the NPC are fundamental for the directional flow of mRNA export.
Collapse
Affiliation(s)
- Rakefet Ben-Yishay
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, Israel.,Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat Gan, Israel
| | - Amir Mor
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, Israel.,Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat Gan, Israel
| | - Amit Shraga
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, Israel.,Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat Gan, Israel
| | - Asaf Ashkenazy-Titelman
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, Israel.,Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat Gan, Israel
| | - Noa Kinor
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, Israel.,Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat Gan, Israel
| | - Avital Schwed-Gross
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, Israel.,Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat Gan, Israel
| | - Avi Jacob
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, Israel.,Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat Gan, Israel
| | - Noga Kozer
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, Israel.,Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat Gan, Israel
| | - Pramod Kumar
- Department of Physics, Bar-Ilan University, Ramat Gan, Israel.,Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat Gan, Israel
| | - Yuval Garini
- Department of Physics, Bar-Ilan University, Ramat Gan, Israel.,Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat Gan, Israel
| | - Yaron Shav-Tal
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, Israel .,Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat Gan, Israel
| |
Collapse
|
7
|
Ben-Yishay R, Ashkenazy AJ, Shav-Tal Y. Dynamic Encounters of Genes and Transcripts with the Nuclear Pore. Trends Genet 2016; 32:419-431. [DOI: 10.1016/j.tig.2016.04.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2016] [Accepted: 04/20/2016] [Indexed: 01/04/2023]
|
8
|
Transcript processing and export kinetics are rate-limiting steps in expressing vertebrate segmentation clock genes. Proc Natl Acad Sci U S A 2013; 110:E4316-24. [PMID: 24151332 DOI: 10.1073/pnas.1308811110] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Sequential production of body segments in vertebrate embryos is regulated by a molecular oscillator (the segmentation clock) that drives cyclic transcription of genes involved in positioning intersegmental boundaries. Mathematical modeling indicates that the period of the clock depends on the total delay kinetics of a negative feedback circuit, including those associated with the synthesis of transcripts encoding clock components [Lewis J (2003) Curr Biol 13(16):1398-1408]. Here, we measure expression delays for three transcripts [Lunatic fringe, Hes7/her1, and Notch-regulated-ankyrin-repeat-protein (Nrarp)], that cycle during segmentation in the zebrafish, chick, and mouse, and provide in vivo measurements of endogenous splicing and export kinetics. We show that mRNA splicing and export are much slower than transcript elongation, with the longest delay (about 16 min in the mouse) being due to mRNA export. We conclude that the kinetics of mRNA and protein production and destruction can account for much of the clock period, and provide strong support for delayed autorepression as the underlying mechanism of the segmentation clock.
Collapse
|
9
|
Abstract
The passage of mRNA molecules from the site of synthesis, through the nucleoplasm and the nuclear pore, en route to the cytoplasm, might appear straightforward. Nonetheless, several decades of detailed examination of this pathway, from high resolution electron microscopy in fixed specimens, through the development of immuno-detection techniques and fluorescence toolkits, to the current era of live-cell imaging, show this to be an eventful journey. In addition to mRNAs, several species of noncoding RNAs travel and function in the nucleus, some being retained within throughout their lifetime. This review will highlight the nucleoplasmic paths taken by mRNAs and noncoding RNAs in eukaryotic cells with special focus on live-cell data and in concurrence with the biophysical nature of the nucleus.
Collapse
Affiliation(s)
- Jonathan Sheinberger
- The Mina & Everard Goodman Faculty of Life Sciences & Institute of Nanotechnology, Bar-Ilan University, Ramat Gan, Israel
| | | |
Collapse
|
10
|
Kula A, Marcello A. Dynamic Post-Transcriptional Regulation of HIV-1 Gene Expression. BIOLOGY 2012; 1:116-33. [PMID: 24832221 PMCID: PMC4009772 DOI: 10.3390/biology1020116] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/11/2012] [Revised: 06/15/2012] [Accepted: 06/18/2012] [Indexed: 01/08/2023]
Abstract
Gene expression of the human immunodeficiency virus type 1 (HIV-1) is a highly regulated process. Basal transcription of the integrated provirus generates early transcripts that encode for the viral products Tat and Rev. Tat promotes the elongation of RNA polymerase while Rev mediates the nuclear export of viral RNAs that contain the Rev-responsive RNA element (RRE). These RNAs are exported from the nucleus to allow expression of Gag-Pol and Env proteins and for the production of full-length genomic RNAs. A balance exists between completely processed mRNAs and RRE-containing RNAs. Rev functions as an adaptor that recruits cellular factors to re-direct singly spliced and unspliced viral RNAs to nuclear export. The aim of this review is to address the dynamic regulation of this post-transcriptional pathway in light of recent findings that implicate several novel cellular cofactors of Rev function.
Collapse
Affiliation(s)
- Anna Kula
- Laboratory of Molecular Virology, International Centre for Genetic Engineering and Biotechnology (ICGEB), Padriciano, Trieste 99 34012, Italy.
| | - Alessandro Marcello
- Laboratory of Molecular Virology, International Centre for Genetic Engineering and Biotechnology (ICGEB), Padriciano, Trieste 99 34012, Italy.
| |
Collapse
|
11
|
Oeffinger M, Zenklusen D. To the pore and through the pore: a story of mRNA export kinetics. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2012; 1819:494-506. [PMID: 22387213 DOI: 10.1016/j.bbagrm.2012.02.011] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2011] [Revised: 02/07/2012] [Accepted: 02/09/2012] [Indexed: 12/26/2022]
Abstract
The evolutionary 'decision' to store genetic information away from the place of protein synthesis, in a separate compartment, has forced eukaryotic cells to establish a system to transport mRNAs from the nucleus to the cytoplasm for translation. To ensure export to be fast and efficient, cells have evolved a complex molecular interplay that is tightly regulated. Over the last few decades, many of the individual players in this process have been described, starting with the composition of the nuclear pore complex to proteins that modulate co-transcriptional events required to prepare an mRNP for export to the cytoplasm. How the interplay between all the factors and processes results in the efficient and selective export of mRNAs from the nucleus and how the export process itself is executed within cells, however, is still not fully understood. Recent advances in using proteomic and single molecule microscopy approaches have provided important insights into the process and its kinetics. This review summarizes these recent advances and how they led to the current view on how cells orchestrate the export of mRNAs. This article is part of a Special Issue entitled: Nuclear Transport and RNA Processing.
Collapse
Affiliation(s)
- Marlene Oeffinger
- Institut de recherches cliniques de Montréal, 110 Avenue des Pins Ouest, Montréal, Québec, Canada.
| | | |
Collapse
|
12
|
Malecki M, Malecki B. Nuclear routing networks span between nuclear pore complexes and genomic DNA to guide nucleoplasmic trafficking of biomolecules. ACTA ACUST UNITED AC 2012; 2. [PMID: 23275893 DOI: 10.4172/2165-7491.1000112] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
In health and disease, biomolecules, which are involved in gene expression, recombination, or reprogramming have to traffic through the nucleoplasm, between nuclear pore complexes (NPCs) and genomic DNA (gDNA). This trafficking is guided by the recently revealed nuclear routing networks (NRNs).In this study, we aimed to investigate, if the NRNs have established associations with the genomic DNA in situ and if the NRNs have capabilities to bind the DNA de novo. Moreover, we aimed to study further, if nucleoplasmic trafficking of the histones, rRNA, and transgenes' vectors, between the NPCs and gDNA, is guided by the NRNs.We used Xenopus laevis oocytes as the model system. We engineered the transgenes' DNA vectors equipped with the SV40 LTA nuclear localization signals (NLS) and/or HIV Rev nuclear export signals (NES). We purified histones, 5S rRNA, and gDNA. We rendered all these molecules superparamagnetic and fluorescent for detection with nuclear magnetic resonance (NMR), total reflection x-ray fluorescence (TXRF), energy dispersive x-ray spectroscopy (EDXS), and electron energy loss spectroscopy (EELS).The NRNs span between the NPCs and genomic DNA. They form firm bonds with the gDNA in situ. After complete digestion of the nucleic acids with the RNases and DNases, the newly added DNA - modified with the dNTP analogs, bonds firmly to the NRNs. Moreover, the NRNs guide the trafficking of the DNA transgenes' vectors - modified with the SV40 LTA NLS, following their import into the nuclei through the NPCs. The pathway is identical to that of histones. The NRNs also guide the trafficking of the DNA transgenes' vectors, modified with the HIV Rev NES, to the NPCs, followed by their export out of the nuclei. Ribosomal RNAs follow the same pathway.To summarize, the NRNs are the structures connecting the NPCs and the gDNA. They guide the trafficking of the biomolecules between the NPCs and the gDNA.
Collapse
Affiliation(s)
- Marek Malecki
- University of Wisconsin, Madison, WI, USA and Phoenix Biomolecular Engineering Foundation, San Francisco, CA, USA
| | | |
Collapse
|
13
|
Mor A, Ben-Yishay R, Shav-Tal Y. On the right track: following the nucleo-cytoplasmic path of an mRNA. Nucleus 2010; 1:492-8. [PMID: 21327092 DOI: 10.4161/nucl.1.6.13515] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2010] [Accepted: 09/03/2010] [Indexed: 11/19/2022] Open
Abstract
The transcription machinery in the eukaryotic nucleus generates messenger RNA molecules that translocate through the nucleoplasm, anchor to a nuclear pore, and find their way out into the cytoplasm. The dynamic aspects of these steps in the expression pathway were examined in order to understand the kinetic time-frames of gene activation and message dissemination. Utilizing live-cell imaging and tracking of single mRNPs containing different sized mRNAs and varying numbers of introns and exons, it was possible to quantify the temporal and spatial characteristics of the nucleoplasmic travels of mRNPs as well as the kinetics of translocation through the nuclear pore.
Collapse
Affiliation(s)
- Amir Mor
- The Mina & Everard Goodman Faculty of Life Sciences & Institute of Nanotechnology, Bar-Ilan University, Ramat Gan, Israel
| | | | | |
Collapse
|