1
|
Mu Y, Han J, Wu M, Li Z, DU K, Wei Y, Wu M, Huang J. Fibrillarin promotes homologous recombination repair by facilitating the recruitment of recombinase RAD51 to DNA damage sites. J Zhejiang Univ Sci B 2023; 24:1165-1173. [PMID: 38057273 PMCID: PMC10710916 DOI: 10.1631/jzus.b2300518] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Accepted: 10/10/2023] [Indexed: 12/08/2023]
Abstract
Eukaryotic organisms constantly face a wide range of internal and external factors that cause damage to their DNA. Failure to accurately and efficiently repair these DNA lesions can result in genomic instability and the development of tumors (Canela et al., 2017). Among the various forms of DNA damage, DNA double-strand breaks (DSBs) are particularly harmful. Two major pathways, non-homologous end joining (NHEJ) and homologous recombination (HR), are primarily responsible for repairing DSBs (Katsuki et al., 2020; Li and Yuan, 2021; Zhang and Gong, 2021; Xiang et al., 2023). NHEJ is an error-prone repair mechanism that simply joins the broken ends together (Blunt et al., 1995; Hartley et al., 1995). In contrast, HR is a precise repair process. It involves multiple proteins in eukaryotic cells, with the RAD51 recombinase being the key player, which is analogous to bacterial recombinase A (RecA) (Shinohara et al., 1992). The central event in HR is the formation of RAD51-single-stranded DNA (ssDNA) nucleoprotein filaments that facilitate homology search and DNA strand invasion, ultimately leading to the initiation of repair synthesis (Miné et al., 2007; Hilario et al., 2009; Ma et al., 2017).
Collapse
Affiliation(s)
- Yanhua Mu
- National-Local Joint Engineering Research Center of Biodiagnosis & Biotherapy, The Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an 710004, China
- The MOE Key Laboratory of Biosystems Homeostasis & Protection and Innovation Center for Cell Signaling Network, Life Sciences Institute, Zhejiang University, Hangzhou 310058, China
| | - Jinhua Han
- Zhejiang Provincial Key Lab of Geriatrics and Geriatrics Institute of Zhejiang Province, Department of Geriatrics, Zhejiang Hospital, Hangzhou 310030, China
| | - Mingjie Wu
- Trauma Center, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310003, China
| | - Zongfang Li
- National-Local Joint Engineering Research Center of Biodiagnosis & Biotherapy, The Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an 710004, China
| | - Ke DU
- National-Local Joint Engineering Research Center of Biodiagnosis & Biotherapy, The Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an 710004, China
| | - Yameng Wei
- National-Local Joint Engineering Research Center of Biodiagnosis & Biotherapy, The Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an 710004, China
| | - Mengjie Wu
- The Affiliated Hospital of Stomatology, School of Stomatology, Zhejiang University School of Medicine, Key Laboratory of Oral Biomedical Research of Zhejiang Province, Hangzhou 310006, China. ,
| | - Jun Huang
- Zhejiang Provincial Key Lab of Geriatrics and Geriatrics Institute of Zhejiang Province, Department of Geriatrics, Zhejiang Hospital, Hangzhou 310030, China.
- Zhejiang Provincial Key Laboratory of Cancer Molecular Cell Biology, Life Sciences Institute, Zhejiang University, Hangzhou 310058, China.
- Department of General Surgery, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou 310016, China.
| |
Collapse
|
2
|
Andrade-Salas A, Canela-Pérez I, Cevallos AM, López-Villaseñor I, Hernández R. Trypanosoma cruzi Fibrillarins: Two paralogous proteins with non-identical signals for nuclear transport. Biochem Biophys Res Commun 2023; 682:274-280. [PMID: 37832384 DOI: 10.1016/j.bbrc.2023.10.025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Revised: 09/14/2023] [Accepted: 10/06/2023] [Indexed: 10/15/2023]
Abstract
Trypanosoma cruzi is a parasitic protozoa causative of Chagas disease. As part of our interest in studying the basic biology of this microorganism, this work reports our observations related to the characterization of motifs and structural domains present in two fibrillarin isoforms (TcFib1 and TcFib2) that were found to be necessary for the nuclear targeting of these nucleolar proteins. Previous characterization of these proteins indicated that they share 68.67% of identical amino acids and are both expressed as nucleolar proteins in T. cruzi epimastigotes. Using an approach based on the transfection of recombinant genes encoding fluorescent fibrillarin-EGFP fusion proteins, this study found evidence for the presence of 4 motifs or protein domains that help target these proteins to the nucleus: The GAR domain and carboxyl terminus in both TcFibs, as well as two lysines and a computationally predicted cNLS in TcFib1. As a distinctive feature, the GAR domain of TcFib2 proved to be essential for the nuclear localization of this protein paralog. Such a difference between TcFib1 and Tcfib2 nuclear localization signals can be explained as the presence of two partially related nuclear import pathways for the two fibrillarin homologues in this organism.
Collapse
Affiliation(s)
- Arturo Andrade-Salas
- Departamento de Biología Molecular y Biotecnología. Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Ciudad Universitaria, CP 04510, México City, Mexico
| | - Israel Canela-Pérez
- Departamento de Biología Molecular y Biotecnología. Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Ciudad Universitaria, CP 04510, México City, Mexico
| | - Ana María Cevallos
- Departamento de Biología Molecular y Biotecnología. Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Ciudad Universitaria, CP 04510, México City, Mexico
| | - Imelda López-Villaseñor
- Departamento de Biología Molecular y Biotecnología. Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Ciudad Universitaria, CP 04510, México City, Mexico
| | - Roberto Hernández
- Departamento de Biología Molecular y Biotecnología. Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Ciudad Universitaria, CP 04510, México City, Mexico.
| |
Collapse
|
3
|
Wang YC, Chang CP, Lai YC, Chan CH, Ou SC, Wang SH, Li C. The conservation and diversity of the exons encoding the glycine and arginine rich domain of the fibrillarin gene in vertebrates, with special focus on reptiles and birds. Gene 2023; 866:147345. [PMID: 36893875 DOI: 10.1016/j.gene.2023.147345] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2022] [Revised: 02/18/2023] [Accepted: 03/02/2023] [Indexed: 03/09/2023]
Abstract
The nucleolar rRNA 2'-O-methyltransferase fibrillarin (FBL) contains a highly conserved methyltransferase domain at the C-terminus and a diverse glycine arginine-rich (GAR) domain at the N-terminus in eukaryotes. We found that a nine-exon configuration of fbl and exon 2-3 encoded GAR domain are conserved and specific in vertebrates. All internal exons except exon 2 and 3 are of the same lengths in different vertebrate lineages. The lengths of exon 2 and 3 vary in different vertebrate species but the ones with longer exon 2 usually have shorter exon 3 complementarily, limiting lengths of the GAR domain within a certain range. In tetrapods except for reptiles, exon 2 appears to be longer than exon 3. We specifically analyzed different lineages of reptiles for their GAR sequences and exon lengths. The lengths of exon 2 in reptiles are around 80-130-nt shorter and the lengths of exon 3 in reptiles are around 50-90 nt longer than those in other tetrapods, all in the GAR-coding regions. An FSPR sequence is present at the beginning of the GAR domain encoded by exon 2 in all vertebrates, and a specific FXSP/G element (X can be K, R, Q, N, and H) exist in the middle of GAR with phenylalanine as the 3rd exon 3-encoded amino acid residue starting from jawfish. Snakes, turtles, and songbirds contain shorter exon 2 compared with lizards, indicating continuous deletions in exon 2 and insertions/duplications in exon 3 in these lineages. Specifically, we confirmed the presence the fbl gene in chicken and validated the RNA expression. Our analyses of the GAR-encoding exons of fbl in vertebrates and reptiles should provide the basis for further evolutionary analyses of more GAR domain encoding proteins.
Collapse
Affiliation(s)
- Yi-Chun Wang
- Department of Biomedical Sciences, Chung Shan Medical University, Taichung, Taiwan; Department of Medical Research, Chung Shan Medical University Hospital, Taichung, Taiwan
| | - Chien-Ping Chang
- Department of Biomedical Sciences, Chung Shan Medical University, Taichung, Taiwan
| | - Yu-Chuan Lai
- Department of Biomedical Sciences, Chung Shan Medical University, Taichung, Taiwan
| | - Chi-Ho Chan
- Department of Medical Research, Chung Shan Medical University Hospital, Taichung, Taiwan; Department of Microbiology and Immunology, Chung Shan Medical University, Taichung, Taiwan
| | - Shan-Chia Ou
- Department of Veterinary Medicine, Graduate Institute of Microbiology and Public Health, National Chung Hsing University, Taichung, Taiwan
| | - Sue-Hong Wang
- Department of Biomedical Sciences, Chung Shan Medical University, Taichung, Taiwan; Department of Medical Research, Chung Shan Medical University Hospital, Taichung, Taiwan
| | - Chuan Li
- Department of Biomedical Sciences, Chung Shan Medical University, Taichung, Taiwan; Department of Medical Research, Chung Shan Medical University Hospital, Taichung, Taiwan.
| |
Collapse
|
4
|
Identification and Characterization of Glycine- and Arginine-Rich Motifs in Proteins by a Novel GAR Motif Finder Program. Genes (Basel) 2023; 14:genes14020330. [PMID: 36833257 PMCID: PMC9957100 DOI: 10.3390/genes14020330] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Revised: 01/17/2023] [Accepted: 01/17/2023] [Indexed: 01/31/2023] Open
Abstract
Glycine- and arginine-rich (GAR) motifs with different combinations of RG/RGG repeats are present in many proteins. The nucleolar rRNA 2'-O-methyltransferase fibrillarin (FBL) contains a conserved long N-terminal GAR domain with more than 10 RGG plus RG repeats separated by specific amino acids, mostly phenylanalines. We developed a GAR motif finder (GMF) program based on the features of the GAR domain of FBL. The G(0,3)-X(0,1)-R-G(1,2)-X(0,5)-G(0,2)-X(0,1)-R-G(1,2) pattern allows the accommodation of extra-long GAR motifs with continuous RG/RGG interrupted by polyglycine or other amino acids. The program has a graphic interface and can easily output the results as .csv and .txt files. We used GMF to show the characteristics of the long GAR domains in FBL and two other nucleolar proteins, nucleolin and GAR1. GMF analyses can illustrate the similarities and also differences between the long GAR domains in the three nucleolar proteins and motifs in other typical RG/RGG-repeat-containing proteins, specifically the FET family members FUS, EWS, and TAF15 in position, motif length, RG/RGG number, and amino acid composition. We also used GMF to analyze the human proteome and focused on the ones with at least 10 RGG plus RG repeats. We showed the classification of the long GAR motifs and their putative correlation with protein/RNA interactions and liquid-liquid phase separation. The GMF algorithm can facilitate further systematic analyses of the GAR motifs in proteins and proteomes.
Collapse
|
5
|
RG/RGG repeats in the C. elegans homologs of Nucleolin and GAR1 contribute to sub-nucleolar phase separation. Nat Commun 2022; 13:6585. [PMID: 36329008 PMCID: PMC9633708 DOI: 10.1038/s41467-022-34225-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Accepted: 10/13/2022] [Indexed: 11/06/2022] Open
Abstract
The intrinsically disordered RG/RGG repeat domain is found in several nucleolar and P-granule proteins, but how it influences their phase separation into biomolecular condensates is unclear. We survey all RG/RGG repeats in C. elegans and uncover nucleolar and P-granule-specific RG/RGG motifs. An uncharacterized protein, K07H8.10, contains the longest nucleolar-like RG/RGG domain in C. elegans. Domain and sequence similarity, as well as nucleolar localization, reveals K07H8.10 (NUCL-1) to be the homolog of Nucleolin, a protein conserved across animals, plants, and fungi, but previously thought to be absent in nematodes. Deleting the RG/RGG repeats within endogenous NUCL-1 and a second nucleolar protein, GARR-1 (GAR1), demonstrates these domains are dispensable for nucleolar accumulation. Instead, their RG/RGG repeats contribute to the phase separation of proteins into nucleolar sub-compartments. Despite this common RG/RGG repeat function, only removal of the GARR-1 RG/RGG domain affects worm fertility and development, decoupling precise sub-nucleolar structure from nucleolar function.
Collapse
|
6
|
Muñoz-Díaz E, Sáez-Vásquez J. Nuclear dynamics: Formation of bodies and trafficking in plant nuclei. FRONTIERS IN PLANT SCIENCE 2022; 13:984163. [PMID: 36082296 PMCID: PMC9445803 DOI: 10.3389/fpls.2022.984163] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Accepted: 08/04/2022] [Indexed: 06/01/2023]
Abstract
The existence of the nucleus distinguishes prokaryotes and eukaryotes. Apart from containing most of the genetic material, the nucleus possesses several nuclear bodies composed of protein and RNA molecules. The nucleus is separated from the cytoplasm by a double membrane, regulating the trafficking of molecules in- and outwards. Here, we investigate the composition and function of the different plant nuclear bodies and molecular clues involved in nuclear trafficking. The behavior of the nucleolus, Cajal bodies, dicing bodies, nuclear speckles, cyclophilin-containing bodies, photobodies and DNA damage foci is analyzed in response to different abiotic stresses. Furthermore, we research the literature to collect the different protein localization signals that rule nucleocytoplasmic trafficking. These signals include the different types of nuclear localization signals (NLSs) for nuclear import, and the nuclear export signals (NESs) for nuclear export. In contrast to these unidirectional-movement signals, the existence of nucleocytoplasmic shuttling signals (NSSs) allows bidirectional movement through the nuclear envelope. Likewise, nucleolar signals are also described, which mainly include the nucleolar localization signals (NoLSs) controlling nucleolar import. In contrast, few examples of nucleolar export signals, called nucleoplasmic localization signals (NpLSs) or nucleolar export signals (NoESs), have been reported. The existence of consensus sequences for these localization signals led to the generation of prediction tools, allowing the detection of these signals from an amino acid sequence. Additionally, the effect of high temperatures as well as different post-translational modifications in nuclear and nucleolar import and export is discussed.
Collapse
Affiliation(s)
- Eduardo Muñoz-Díaz
- Centre National de la Recherche Scientifique (CNRS), Laboratoire Génome et Développement des Plantes, UMR 5096, Perpignan, France
- Univ. Perpignan Via Domitia, Laboratoire Génome et Développement des Plantes, UMR 5096, Perpignan, France
| | - Julio Sáez-Vásquez
- Centre National de la Recherche Scientifique (CNRS), Laboratoire Génome et Développement des Plantes, UMR 5096, Perpignan, France
- Univ. Perpignan Via Domitia, Laboratoire Génome et Développement des Plantes, UMR 5096, Perpignan, France
| |
Collapse
|
7
|
Sithamparam M, Satthiyasilan N, Chen C, Jia TZ, Chandru K. A material-based panspermia hypothesis: The potential of polymer gels and membraneless droplets. Biopolymers 2022; 113:e23486. [PMID: 35148427 DOI: 10.1002/bip.23486] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Revised: 01/27/2022] [Accepted: 01/28/2022] [Indexed: 01/08/2023]
Abstract
The Panspermia hypothesis posits that either life's building blocks (molecular Panspermia) or life itself (organism-based Panspermia) may have been interplanetarily transferred to facilitate the origins of life (OoL) on a given planet, complementing several current OoL frameworks. Although many spaceflight experiments were performed in the past to test for potential terrestrial organisms as Panspermia seeds, it is uncertain whether such organisms will likely "seed" a new planet even if they are able to survive spaceflight. Therefore, rather than using organisms, using abiotic chemicals as seeds has been proposed as part of the molecular Panspermia hypothesis. Here, as an extension of this hypothesis, we introduce and review the plausibility of a polymeric material-based Panspermia seed (M-BPS) as a theoretical concept, where the type of polymeric material that can function as a M-BPS must be able to: (1) survive spaceflight and (2) "function", i.e., contingently drive chemical evolution toward some form of abiogenesis once arriving on a foreign planet. We use polymeric gels as a model example of a potential M-BPS. Polymeric gels that can be prebiotically synthesized on one planet (such as polyester gels) could be transferred to another planet via meteoritic transfer, where upon landing on a liquid bearing planet, can assemble into structures containing cellular-like characteristics and functionalities. Such features presupposed that these gels can assemble into compartments through phase separation to accomplish relevant functions such as encapsulation of primitive metabolic, genetic and catalytic materials, exchange of these materials, motion, coalescence, and evolution. All of these functions can result in the gels' capability to alter local geochemical niches on other planets, thereby allowing chemical evolution to lead to OoL events.
Collapse
Affiliation(s)
- Mahendran Sithamparam
- Space Science Center (ANGKASA), Institute of Climate Change, National University of Malaysia (UKM), Bangi, Selangor, Malaysia
| | - Nirmell Satthiyasilan
- Space Science Center (ANGKASA), Institute of Climate Change, National University of Malaysia (UKM), Bangi, Selangor, Malaysia
| | - Chen Chen
- Earth-Life Science Institute, Tokyo Institute of Technology, Tokyo, Japan
| | - Tony Z Jia
- Earth-Life Science Institute, Tokyo Institute of Technology, Tokyo, Japan.,Blue Marble Space Institute of Science, Seattle, Washington, USA
| | - Kuhan Chandru
- Space Science Center (ANGKASA), Institute of Climate Change, National University of Malaysia (UKM), Bangi, Selangor, Malaysia
| |
Collapse
|
8
|
Phase Separation of Intrinsically Disordered Nucleolar Proteins Relate to Localization and Function. Int J Mol Sci 2021; 22:ijms222313095. [PMID: 34884901 PMCID: PMC8657925 DOI: 10.3390/ijms222313095] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Revised: 11/11/2021] [Accepted: 11/28/2021] [Indexed: 01/10/2023] Open
Abstract
The process of phase separation allows for the establishment and formation of subcompartmentalized structures, thus enabling cells to perform simultaneous processes with precise organization and low energy requirements. Chemical modifications of proteins, RNA, and lipids alter the molecular environment facilitating enzymatic reactions at higher concentrations in particular regions of the cell. In this review, we discuss the nucleolus as an example of the establishment, dynamics, and maintenance of a membraneless organelle with a high level of organization.
Collapse
|
9
|
Lu J, Qian J, Xu Z, Yin S, Zhou L, Zheng S, Zhang W. Emerging Roles of Liquid-Liquid Phase Separation in Cancer: From Protein Aggregation to Immune-Associated Signaling. Front Cell Dev Biol 2021; 9:631486. [PMID: 34235141 PMCID: PMC8255971 DOI: 10.3389/fcell.2021.631486] [Citation(s) in RCA: 38] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Accepted: 05/14/2021] [Indexed: 12/12/2022] Open
Abstract
Liquid-liquid Phase Separation (LLPS) of proteins and nucleic acids has emerged as a new paradigm in the study of cellular activities. It drives the formation of liquid-like condensates containing biomolecules in the absence of membrane structures in living cells. In addition, typical membrane-less condensates such as nuclear speckles, stress granules and cell signaling clusters play important roles in various cellular activities, including regulation of transcription, cellular stress response and signal transduction. Previous studies highlighted the biophysical and biochemical principles underlying the formation of these liquid condensates. The studies also showed how these principles determine the molecular properties, LLPS behavior, and composition of liquid condensates. While the basic rules driving LLPS are continuously being uncovered, their function in cellular activities is still unclear, especially within a pathological context. Therefore, the present review summarizes the recent progress made on the existing roles of LLPS in cancer, including cancer-related signaling pathways, transcription regulation and maintenance of genome stability. Additionally, the review briefly introduces the basic rules of LLPS, and cellular signaling that potentially plays a role in cancer, including pathways relevant to immune responses and autophagy.
Collapse
Affiliation(s)
- Jiahua Lu
- Division of Hepatobiliary and Pancreatic Surgery, Department of Surgery, First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China.,NHC Key Laboratory of Combined Multi-Organ Transplantation, Hangzhou, China.,Key Laboratory of the Diagnosis and Treatment of Organ Transplantation, Research Unit of Collaborative Diagnosis and Treatment For Hepatobiliary and Pancreatic Cancer, Chinese Academy of Medical Sciences, Hangzhou, China.,Key Laboratory of Organ Transplantation, Research Center for Diagnosis and Treatment of Hepatobiliary Diseases, Hangzhou, China
| | - Junjie Qian
- NHC Key Laboratory of Combined Multi-Organ Transplantation, Hangzhou, China.,Key Laboratory of the Diagnosis and Treatment of Organ Transplantation, Research Unit of Collaborative Diagnosis and Treatment For Hepatobiliary and Pancreatic Cancer, Chinese Academy of Medical Sciences, Hangzhou, China.,Key Laboratory of Organ Transplantation, Research Center for Diagnosis and Treatment of Hepatobiliary Diseases, Hangzhou, China.,Organ Transplantation Institute, Zhejiang University, Hangzhou, China
| | - Zhentian Xu
- Division of Hepatobiliary and Pancreatic Surgery, Department of Surgery, First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China.,NHC Key Laboratory of Combined Multi-Organ Transplantation, Hangzhou, China.,Key Laboratory of the Diagnosis and Treatment of Organ Transplantation, Research Unit of Collaborative Diagnosis and Treatment For Hepatobiliary and Pancreatic Cancer, Chinese Academy of Medical Sciences, Hangzhou, China.,Key Laboratory of Organ Transplantation, Research Center for Diagnosis and Treatment of Hepatobiliary Diseases, Hangzhou, China
| | - Shengyong Yin
- NHC Key Laboratory of Combined Multi-Organ Transplantation, Hangzhou, China.,Key Laboratory of the Diagnosis and Treatment of Organ Transplantation, Research Unit of Collaborative Diagnosis and Treatment For Hepatobiliary and Pancreatic Cancer, Chinese Academy of Medical Sciences, Hangzhou, China.,Key Laboratory of Organ Transplantation, Research Center for Diagnosis and Treatment of Hepatobiliary Diseases, Hangzhou, China.,Organ Transplantation Institute, Zhejiang University, Hangzhou, China
| | - Lin Zhou
- NHC Key Laboratory of Combined Multi-Organ Transplantation, Hangzhou, China.,Key Laboratory of the Diagnosis and Treatment of Organ Transplantation, Research Unit of Collaborative Diagnosis and Treatment For Hepatobiliary and Pancreatic Cancer, Chinese Academy of Medical Sciences, Hangzhou, China.,Key Laboratory of Organ Transplantation, Research Center for Diagnosis and Treatment of Hepatobiliary Diseases, Hangzhou, China.,Organ Transplantation Institute, Zhejiang University, Hangzhou, China
| | - Shusen Zheng
- Division of Hepatobiliary and Pancreatic Surgery, Department of Surgery, First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China.,NHC Key Laboratory of Combined Multi-Organ Transplantation, Hangzhou, China.,Key Laboratory of the Diagnosis and Treatment of Organ Transplantation, Research Unit of Collaborative Diagnosis and Treatment For Hepatobiliary and Pancreatic Cancer, Chinese Academy of Medical Sciences, Hangzhou, China.,Key Laboratory of Organ Transplantation, Research Center for Diagnosis and Treatment of Hepatobiliary Diseases, Hangzhou, China.,Organ Transplantation Institute, Zhejiang University, Hangzhou, China.,Shulan (Hangzhou) Hospital Affiliated to Shulan International Medical College, Zhejiang Shuren University, Hangzhou, China
| | - Wu Zhang
- Organ Transplantation Institute, Zhejiang University, Hangzhou, China.,Shulan (Hangzhou) Hospital Affiliated to Shulan International Medical College, Zhejiang Shuren University, Hangzhou, China
| |
Collapse
|
10
|
Chen C, Li P, Luo W, Nakamura Y, Dimo VS, Kanekura K, Hayamizu Y. Diffusion of LLPS Droplets Consisting of Poly(PR) Dipeptide Repeats and RNA on Chemically Modified Glass Surface. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:5635-5641. [PMID: 33929866 DOI: 10.1021/acs.langmuir.1c00493] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The liquid-liquid phase separation (LLPS) of proteins and RNA molecules has emerged in recent years as an important physicochemical process to explain the organization of membrane-less organelles in living cells and cellular functions and even some fatal neurodegenerative diseases, such as Amyotrophic Lateral Sclerosis (ALS) due to the spontaneous condensation and growth of LLPS droplets. In general, the characterization of LLPS droplets has been performed by optical microscopy, where we need transparent substrates. By virtue of the liquid and wetting properties of LLPS droplets on a glass surface, there have been some technical protocols recommended to immobilize droplets on the surfaces. However, interactions between LLPS droplets and glass surfaces still remain unclear. Here, we investigated the surface diffusion of LLPS droplets on the glass surface to understand the interactions of droplets in a dynamic manner, and employed chemically modified glass surface with charges to investigate their Coulombic interaction with the surface. Using the single-particle tracking method, we first analyzed the diffusion of droplets on an untreated glass surface. Then, we compared the diffusion modes of LLPS droplets on each substrate and found that there were two major states of droplets on a solid surface: fix and diffusion mode for the LLPS droplet diffusion. While untreated glass showed a diffusion of droplets mainly, chemically modified glass with positive charges exhibited droplets fixed on the surface. It could arise from the Coulombic interaction between droplets and solid surface, where LLPS droplets have a negative ζ-potential. Our findings on the dynamics of LLPS at the solid/liquid interface could provide a novel insight to advance fundamental studies for understanding the LLPS formation.
Collapse
Affiliation(s)
- Chen Chen
- Department of Materials Science and Engineering, School of Materials and Chemical Technology, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550, Japan
| | - Peiying Li
- Center for Biosystems Dynamics Research, RIKEN, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama 230-0045, Japan
| | - Wei Luo
- Department of Materials Science and Engineering, School of Materials and Chemical Technology, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550, Japan
| | - Yoshiki Nakamura
- Department of Materials Science and Engineering, School of Materials and Chemical Technology, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550, Japan
| | - Vanessa Seudo Dimo
- Department of Materials Science and Engineering, School of Materials and Chemical Technology, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550, Japan
| | - Kohsuke Kanekura
- Department of Molecular Pathology, Tokyo Medical University, 6-1-1 Shinjuku, Shinjuku-ku, Tokyo 160-8402, Japan
| | - Yuhei Hayamizu
- Department of Materials Science and Engineering, School of Materials and Chemical Technology, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550, Japan
| |
Collapse
|
11
|
Fast and synchronized fluctuations of cortical actin negatively correlate with nucleoli liquid-liquid phase separation in T cells. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2020; 49:409-423. [PMID: 32666133 DOI: 10.1007/s00249-020-01446-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 07/14/2019] [Revised: 03/10/2020] [Accepted: 07/02/2020] [Indexed: 12/11/2022]
Abstract
Liquid-liquid phase separation is an important mechanism by which eukaryotic cells functionally organize their intracellular content and has been related to cell malignancy and neurodegenerative diseases. These cells also undergo ATP-driven mechanical fluctuations, yet the effect of these fluctuations on the liquid-liquid phase separation remains poorly understood. Here, we employ high-resolution microscopy and atomic force microscopy of live Jurkat T cells to characterize the spectrum of their mechanical fluctuations, and to relate these fluctuations to the extent of nucleoli liquid-liquid phase separation (LLPS). We find distinct fluctuation of the cytoskeleton and of the cell diameter around 110 Hz, which depend on ATP and on myosin activity. Importantly, these fluctuations negatively correlate to nucleoli LLPS. According to a model of cell viscoelasticity, we propose that these fluctuations generate mechanical work that increases intracellular homogeneity by inhibiting LLPS. Thus, active mechanical fluctuations serve as an intracellular regulatory mechanism that could affect multiple pathophysiological conditions.
Collapse
|
12
|
Shubina MY, Arifulin EA, Sorokin DV, Sosina MA, Tikhomirova MA, Serebryakova MV, Smirnova T, Sokolov SS, Musinova YR, Sheval EV. The GAR domain integrates functions that are necessary for the proper localization of fibrillarin (FBL) inside eukaryotic cells. PeerJ 2020; 8:e9029. [PMID: 32377452 PMCID: PMC7194090 DOI: 10.7717/peerj.9029] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Accepted: 03/31/2020] [Indexed: 01/25/2023] Open
Abstract
Fibrillarin (FBL) is an essential nucleolar protein that participates in pre-rRNA methylation and processing. The methyltransferase domain of FBL is an example of an extremely well-conserved protein domain in which the amino acid sequence was not substantially modified during the evolution from Archaea to Eukaryota. An additional N-terminal glycine–arginine-rich (GAR) domain is present in the FBL of eukaryotes. Here, we demonstrate that the GAR domain is involved in FBL functioning and integrates the functions of the nuclear localization signal and the nucleolar localization signal (NoLS). The methylation of the arginine residues in the GAR domain is necessary for nuclear import but decreases the efficiency of nucleolar retention via the NoLS. The presented data indicate that the GAR domain can be considered an evolutionary innovation that integrates several functional activities and thereby adapts FBL to the highly compartmentalized content of the eukaryotic cell.
Collapse
Affiliation(s)
- Maria Y Shubina
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia
| | - Eugene A Arifulin
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia
| | - Dmitry V Sorokin
- Laboratory of Mathematical Methods of Image Processing, Faculty of Computational Mathematics and Cybernetics, Lomonosov Moscow State University, Moscow, Russia
| | - Mariya A Sosina
- Koltzov Institute of Developmental Biology, Russian Academy of Sciences, Moscow, Russia
| | - Maria A Tikhomirova
- Koltzov Institute of Developmental Biology, Russian Academy of Sciences, Moscow, Russia.,Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow, Russia
| | - Marina V Serebryakova
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia
| | - Tatiana Smirnova
- Department of Cell Biology and Histology, Faculty of Biology, Lomonosov Moscow State University, Moscow, Russia
| | - Svyatoslav S Sokolov
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia
| | - Yana R Musinova
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia.,Koltzov Institute of Developmental Biology, Russian Academy of Sciences, Moscow, Russia.,Skobelkin State Scientific Center of Laser Medicine FMBA, Moscow, Russia
| | - Eugene V Sheval
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia.,Department of Cell Biology and Histology, Faculty of Biology, Lomonosov Moscow State University, Moscow, Russia.,LIA 1066 LFR2O French-Russian Joint Cancer Research Laboratory, Villejuif, France
| |
Collapse
|
13
|
Guillen-Chable F, Rodríguez Corona U, Pereira-Santana A, Bayona A, Rodríguez-Zapata LC, Aquino C, Šebestová L, Vitale N, Hozak P, Castano E. Fibrillarin Ribonuclease Activity is Dependent on the GAR Domain and Modulated by Phospholipids. Cells 2020; 9:cells9051143. [PMID: 32384686 PMCID: PMC7290794 DOI: 10.3390/cells9051143] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Revised: 04/24/2020] [Accepted: 04/29/2020] [Indexed: 12/16/2022] Open
Abstract
Fibrillarin is a highly conserved nucleolar methyltransferase responsible for ribosomal RNA methylation across evolution from Archaea to humans. It has been reported that fibrillarin is involved in the methylation of histone H2A in nucleoli and other processes, including viral progression, cellular stress, nuclear shape, and cell cycle progression. We show that fibrillarin has an additional activity as a ribonuclease. The activity is affected by phosphoinositides and phosphatidic acid and insensitive to ribonuclease inhibitors. Furthermore, the presence of phosphatidic acid releases the fibrillarin-U3 snoRNA complex. We show that the ribonuclease activity localizes to the GAR (glycine/arginine-rich) domain conserved in a small group of RNA interacting proteins. The introduction of the GAR domain occurred in evolution in the transition from archaea to eukaryotic cells. The interaction of this domain with phospholipids may allow a phase separation of this protein in nucleoli.
Collapse
Affiliation(s)
- Francisco Guillen-Chable
- Biochemistry and Molecular Plant Biology Department, Centro de Investigación Científica de Yucatán, A.C. Calle 43 No. 130, Colonia Chuburná de Hidalgo, Mérida C.P. 97200, Yucatán, Mexico; (F.G.-C.); (U.R.C.); (A.B.); (C.A.)
| | - Ulises Rodríguez Corona
- Biochemistry and Molecular Plant Biology Department, Centro de Investigación Científica de Yucatán, A.C. Calle 43 No. 130, Colonia Chuburná de Hidalgo, Mérida C.P. 97200, Yucatán, Mexico; (F.G.-C.); (U.R.C.); (A.B.); (C.A.)
| | - Alejandro Pereira-Santana
- Industrial Biotechnology Department, Centro de Investigación y Asistencia en Tecnología y Diseño del Estado de Jalisco, A.C., Camino Arenero 1227, el Bajio, Zapopan C.P. 45019, Jalisco, Mexico;
- Dirección de Cátedras, Consejo Nacional de Ciencia y Tecnología, Av. Insurgentes Sur 1582, Alcaldia Benito Juarez C.P. 03940, Ciudad de Mexico, Mexico
| | - Andrea Bayona
- Biochemistry and Molecular Plant Biology Department, Centro de Investigación Científica de Yucatán, A.C. Calle 43 No. 130, Colonia Chuburná de Hidalgo, Mérida C.P. 97200, Yucatán, Mexico; (F.G.-C.); (U.R.C.); (A.B.); (C.A.)
| | - Luis Carlos Rodríguez-Zapata
- Biotechnology Department, Centro de Investigación Científica de Yucatán, A.C. Calle 43 No. 130, Colonia Chuburná de Hidalgo, Mérida C.P. 97200, Yucatan, Mexico;
| | - Cecilia Aquino
- Biochemistry and Molecular Plant Biology Department, Centro de Investigación Científica de Yucatán, A.C. Calle 43 No. 130, Colonia Chuburná de Hidalgo, Mérida C.P. 97200, Yucatán, Mexico; (F.G.-C.); (U.R.C.); (A.B.); (C.A.)
| | - Lenka Šebestová
- Department of Biology of the Cell Nucleus, Institute of Molecular Genetics of the CAS, v.v.i., Videnska 1083, 142 20 Prague, Czech Republic; (L.Š.); (P.H.)
- Faculty of Science, Charles University, Albertov 6, 128 00 Prague, Czech Republic
| | - Nicolas Vitale
- Institute of Celullar and Integrative Neuroscience (INCI), UPR-3212 The French National Centre for Scientific Research & University of Strasbourg, 67000 Strasbourg, France;
| | - Pavel Hozak
- Department of Biology of the Cell Nucleus, Institute of Molecular Genetics of the CAS, v.v.i., Videnska 1083, 142 20 Prague, Czech Republic; (L.Š.); (P.H.)
| | - Enrique Castano
- Biochemistry and Molecular Plant Biology Department, Centro de Investigación Científica de Yucatán, A.C. Calle 43 No. 130, Colonia Chuburná de Hidalgo, Mérida C.P. 97200, Yucatán, Mexico; (F.G.-C.); (U.R.C.); (A.B.); (C.A.)
- Correspondence:
| |
Collapse
|
14
|
Abstract
Intracellular dynamics is highly complex, and includes diffusion of poly-dispersed objects in a non-homogeneous, out-of-equilibrium medium. Assuming non-equilibrium steady-state, we developed a framework that relates non-equilibrium fluctuations to diffusion, and generalized entropy in cells. We employed imaging of live Jurkat T cells, and showed that active cells have higher diffusion parameters (Kα and α) and entropy relative to the same cells after ATP depletion. Kα and α were related in ATP-depleted cells while this relation was not apparent in untreated cells, probably due to non-equilibrium applied work. Next we evaluated the effect of intracellular diffusion and entropy on the cell content homogeneity, which was displayed by the extent of its liquid–liquid phase separation (LLPS). Correlations between intracellular diffusion parameters, entropy and cell homogeneity could be demonstrated only in active cells while these correlations disappeared after ATP depletion. We conclude that non-equilibrium contributions to diffusivity and entropy by ATP-dependent mechanical work allow cells to control their content homogeneity and LLPS state. Such understanding may enable better intervention in extreme LLPS conditions associated with various cell malignancies and degenerative diseases.
Collapse
|
15
|
Identification of Functional Domain(s) of Fibrillarin Interacted with p2 of Rice stripe virus. CANADIAN JOURNAL OF INFECTIOUS DISEASES & MEDICAL MICROBIOLOGY 2018; 2018:8402839. [PMID: 29736196 PMCID: PMC5875058 DOI: 10.1155/2018/8402839] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/04/2017] [Accepted: 12/06/2017] [Indexed: 11/30/2022]
Abstract
p2 of Rice stripe virus may promote virus systemic infection by interacting with the full length of fibrillarin from Nicotiana benthamiana (NbFib2) in the nucleolus and cajal body (CB). NbFib2 contains three functional domains. We used yeast two-hybrid, colocalization, and bimolecular fluorescence complementation (BiFC) assays to study the interactions between p2 and the three domains of NbFib2, namely, the N-terminal fragment containing a glycine and arginine-rich (GAR) domain, the central RNA-binding domain, and the C-terminal fragment containing an α-helical domain. The results show that the N-terminal domain is indispensable for NbFib2 to localize in the nucleolus and cajal body. p2 binds all three regions of NbFib2, and they target to the nucleus but fail to the nucleolus and cajal bodies (CBs).
Collapse
|
16
|
Shin Y, Brangwynne CP. Liquid phase condensation in cell physiology and disease. Science 2018; 357:357/6357/eaaf4382. [PMID: 28935776 DOI: 10.1126/science.aaf4382] [Citation(s) in RCA: 2098] [Impact Index Per Article: 349.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Phase transitions are ubiquitous in nonliving matter, and recent discoveries have shown that they also play a key role within living cells. Intracellular liquid-liquid phase separation is thought to drive the formation of condensed liquid-like droplets of protein, RNA, and other biomolecules, which form in the absence of a delimiting membrane. Recent studies have elucidated many aspects of the molecular interactions underlying the formation of these remarkable and ubiquitous droplets and the way in which such interactions dictate their material properties, composition, and phase behavior. Here, we review these exciting developments and highlight key remaining challenges, particularly the ability of liquid condensates to both facilitate and respond to biological function and how their metastability may underlie devastating protein aggregation diseases.
Collapse
Affiliation(s)
- Yongdae Shin
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ, USA
| | - Clifford P Brangwynne
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ, USA.
| |
Collapse
|
17
|
Rodriguez-Corona U, Pereira-Santana A, Sobol M, Rodriguez-Zapata LC, Hozak P, Castano E. Novel Ribonuclease Activity Differs between Fibrillarins from Arabidopsis thaliana. FRONTIERS IN PLANT SCIENCE 2017; 8:1878. [PMID: 29163603 PMCID: PMC5674935 DOI: 10.3389/fpls.2017.01878] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Accepted: 10/16/2017] [Indexed: 05/09/2023]
Abstract
Fibrillarin is one of the most important nucleolar proteins that have been shown as essential for life. Fibrillarin localizes primarily at the periphery between fibrillar center and dense fibrillar component as well as in Cajal bodies. In most plants there are at least two different genes for fibrillarin. In Arabidopsis thaliana both genes show high level of expression in transcriptionally active cells. Here, we focus on two important differences between A. thaliana fibrillarins. First and most relevant is the enzymatic activity by AtFib2. The AtFib2 shows a novel ribonuclease activity that is not seen with AtFib1. Second is a difference in the ability to interact with phosphoinositides and phosphatidic acid between both proteins. We also show that the novel ribonuclease activity as well as the phospholipid binding region of fibrillarin is confine to the GAR domain. The ribonuclease activity of fibrillarin reveals in this study represents a new role for this protein in rRNA processing.
Collapse
Affiliation(s)
- Ulises Rodriguez-Corona
- Unidad de Bioquímica y Biología Molecular de Plantas, Centro de Investigación Científica de Yucatán, Mérida, Mexico
| | - Alejandro Pereira-Santana
- Biosystematics Group, Department of Plant Sciences, Wageningen University and Research, Wageningen, Netherlands
| | - Margarita Sobol
- Department of Biology of the Cell Nucleus, Institute of Molecular Genetics of the Academy of Sciences of the Czech Republic, Prague, Czechia
| | | | - Pavel Hozak
- Department of Biology of the Cell Nucleus, Institute of Molecular Genetics of the Academy of Sciences of the Czech Republic, Prague, Czechia
| | - Enrique Castano
- Unidad de Bioquímica y Biología Molecular de Plantas, Centro de Investigación Científica de Yucatán, Mérida, Mexico
- *Correspondence: Enrique Castano,
| |
Collapse
|
18
|
Trinkle-Mulcahy L, Sleeman JE. The Cajal body and the nucleolus: "In a relationship" or "It's complicated"? RNA Biol 2016; 14:739-751. [PMID: 27661468 DOI: 10.1080/15476286.2016.1236169] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
From their initial identification as 'nucleolar accessory bodies' more than a century ago, the relationship between Cajal bodies and nucleoli has been a subject of interest and controversy. In this review, we seek to place recent developments in the understanding of the physical and functional relationships between the 2 structures in the context of historical observations. Biophysical models of nuclear body formation, the molecular nature of CB/nucleolus interactions and the increasing list of joint roles for CBs and nucleoli, predominantly in assembling ribonucleoprotein (RNP) complexes, are discussed.
Collapse
Affiliation(s)
- Laura Trinkle-Mulcahy
- a Department of Cellular and Molecular Medicine , Ottawa Institute of Systems Biology, University of Ottawa , Ottawa , ON , Canada
| | - Judith E Sleeman
- b BSRC Complex, School of Biology, University of St Andrews , UK
| |
Collapse
|
19
|
Shubina MY, Musinova YR, Sheval EV. Nucleolar methyltransferase fibrillarin: Evolution of structure and functions. BIOCHEMISTRY (MOSCOW) 2016; 81:941-50. [DOI: 10.1134/s0006297916090030] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
|
20
|
Sánchez-Hernández N, Boireau S, Schmidt U, Muñoz-Cobo JP, Hernández-Munain C, Bertrand E, Suñé C. The in vivo dynamics of TCERG1, a factor that couples transcriptional elongation with splicing. RNA (NEW YORK, N.Y.) 2016; 22:571-582. [PMID: 26873599 PMCID: PMC4793212 DOI: 10.1261/rna.052795.115] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/08/2015] [Accepted: 12/23/2015] [Indexed: 06/05/2023]
Abstract
Coupling between transcription and RNA processing is key for gene regulation. Using live-cell photobleaching techniques, we investigated the factor TCERG1, which coordinates transcriptional elongation with splicing. We demonstrate that TCERG1 is highly mobile in the nucleoplasm and that this mobility is slightly decreased when it is associated with speckles. Dichloro-1-β-D-ribofuranosylbenzimidazole (DRB) but not α-amanitin treatment reduced the mobility of TCERG1, which suggests interaction with paused transcription elongation complexes. We found that TCERG1 mobility is rapid at the transcription site (TS) of a reporter that splices post-transcriptionally and that TCERG1 is recruited to the active TS independent of the CTD of RNAPII, thus excluding phosphorylated CTD as a requirement for recruiting this factor to the TS. Importantly, the mobility of TCERG1 is reduced when the reporter splices cotranscriptionally, which suggests that TCERG1 forms new macromolecular complexes when splicing occurs cotranscriptionally. In this condition, spliceostatin A has no effect, indicating that TCERG1 rapidly binds and dissociates from stalled spliceosomal complexes and that the mobility properties of TCERG1 do not depend on events occurring after the initial spliceosome formation. Taken together, these data suggest that TCERG1 binds independently to elongation and splicing complexes, thus performing their coupling by transient interactions rather than by stable association with one or the other complexes. This finding has conceptual implications for understanding the coupling between transcription and RNA processing.
Collapse
Affiliation(s)
- Noemí Sánchez-Hernández
- Department of Molecular Biology, Instituto de Parasitología y Biomedicina "López Neyra" (IPBLN-CSIC), PTS, Granada 18016, Spain
| | - Stéphanie Boireau
- Institut de Génétique Moléculaire de Montpellier, Centre National de la Recherche Scientifique, 34293 Montpellier, France
| | - Ute Schmidt
- Institut de Génétique Moléculaire de Montpellier, Centre National de la Recherche Scientifique, 34293 Montpellier, France
| | - Juan Pablo Muñoz-Cobo
- Department of Molecular Biology, Instituto de Parasitología y Biomedicina "López Neyra" (IPBLN-CSIC), PTS, Granada 18016, Spain
| | - Cristina Hernández-Munain
- Department of Cell Biology and Immunology, Instituto de Parasitología y Biomedicina "López Neyra" (IPBLN-CSIC), PTS, Granada 18016, Spain
| | - Edouard Bertrand
- Institut de Génétique Moléculaire de Montpellier, Centre National de la Recherche Scientifique, 34293 Montpellier, France
| | - Carlos Suñé
- Department of Molecular Biology, Instituto de Parasitología y Biomedicina "López Neyra" (IPBLN-CSIC), PTS, Granada 18016, Spain
| |
Collapse
|
21
|
Zheng L, Yao J, Gao F, Chen L, Zhang C, Lian L, Xie L, Wu Z, Xie L. The Subcellular Localization and Functional Analysis of Fibrillarin2, a Nucleolar Protein in Nicotiana benthamiana. BIOMED RESEARCH INTERNATIONAL 2016; 2016:2831287. [PMID: 26885505 PMCID: PMC4738988 DOI: 10.1155/2016/2831287] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/14/2015] [Accepted: 12/01/2015] [Indexed: 01/28/2023]
Abstract
Nucleolar proteins play important roles in plant cytology, growth, and development. Fibrillarin2 is a nucleolar protein of Nicotiana benthamiana (N. benthamiana). Its cDNA was amplified by RT-PCR and inserted into expression vector pEarley101 labeled with yellow fluorescent protein (YFP). The fusion protein was localized in the nucleolus and Cajal body of leaf epidermal cells of N. benthamiana. The N. benthamiana fibrillarin2 (NbFib2) protein has three functional domains (i.e., glycine and arginine rich domain, RNA-binding domain, and α-helical domain) and a nuclear localization signal (NLS) in C-terminal. The protein 3D structure analysis predicted that NbFib2 is an α/β protein. In addition, the virus induced gene silencing (VIGS) approach was used to determine the function of NbFib2. Our results showed that symptoms including growth retardation, organ deformation, chlorosis, and necrosis appeared in NbFib2-silenced N. benthamiana.
Collapse
Affiliation(s)
- Luping Zheng
- Key Laboratory of Biopesticide and Chemical Biology, Ministry of Education, Fujian Agriculture and Forestry University, Fuzhou 350002, China
- Key Laboratory of Plant Virology of Fujian Province, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Jinai Yao
- Institute of Plant Protection, Fujian Provincial Academy of Agricultural Sciences, Fuzhou 350002, China
| | - Fangluan Gao
- Key Laboratory of Biopesticide and Chemical Biology, Ministry of Education, Fujian Agriculture and Forestry University, Fuzhou 350002, China
- Key Laboratory of Plant Virology of Fujian Province, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Lin Chen
- Key Laboratory of Plant Virology of Fujian Province, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Chao Zhang
- Key Laboratory of Plant Virology of Fujian Province, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Lingli Lian
- Key Laboratory of Plant Virology of Fujian Province, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Liyan Xie
- Key Laboratory of Plant Virology of Fujian Province, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Zujian Wu
- Key Laboratory of Plant Virology of Fujian Province, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Lianhui Xie
- Key Laboratory of Plant Virology of Fujian Province, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| |
Collapse
|
22
|
Schrumpfová PP, Vychodilová I, Hapala J, Schořová Š, Dvořáček V, Fajkus J. Telomere binding protein TRB1 is associated with promoters of translation machinery genes in vivo. PLANT MOLECULAR BIOLOGY 2016; 90:189-206. [PMID: 26597966 DOI: 10.1007/s11103-015-0409-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Accepted: 11/16/2015] [Indexed: 05/24/2023]
Abstract
Recently we characterised TRB1, a protein from a single-myb-histone family, as a structural and functional component of telomeres in Arabidopsis thaliana. TRB proteins, besides their ability to bind specifically to telomeric DNA using their N-terminally positioned myb-like domain of the same type as in human shelterin proteins TRF1 or TRF2, also possess a histone-like domain which is involved in protein-protein interactions e.g., with POT1b. Here we set out to investigate the genome-wide localization pattern of TRB1 to reveal its preferential sites of binding to chromatin in vivo and its potential functional roles in the genome-wide context. Our results demonstrate that TRB1 is preferentially associated with promoter regions of genes involved in ribosome biogenesis, in addition to its roles at telomeres. This preference coincides with the frequent occurrence of telobox motifs in the upstream regions of genes in this category, but it is not restricted to the presence of a telobox. We conclude that TRB1 shows a specific genome-wide distribution pattern which suggests its role in regulation of genes involved in biogenesis of the translational machinery, in addition to its preferential telomeric localization.
Collapse
Affiliation(s)
- Petra Procházková Schrumpfová
- Mendel Centre for Plant Genomics and Proteomics, CEITEC - Central European Institute of Technology, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic
- Laboratory of Functional Genomics and Proteomics, National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic
| | - Ivona Vychodilová
- Mendel Centre for Plant Genomics and Proteomics, CEITEC - Central European Institute of Technology, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic
- Laboratory of Functional Genomics and Proteomics, National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic
| | - Jan Hapala
- Mendel Centre for Plant Genomics and Proteomics, CEITEC - Central European Institute of Technology, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic
- Laboratory of Functional Genomics and Proteomics, National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic
| | - Šárka Schořová
- Mendel Centre for Plant Genomics and Proteomics, CEITEC - Central European Institute of Technology, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic
- Laboratory of Functional Genomics and Proteomics, National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic
| | - Vojtěch Dvořáček
- Mendel Centre for Plant Genomics and Proteomics, CEITEC - Central European Institute of Technology, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic
- Institute of Biophysics, Academy of Sciences of the Czech Republic, v.v.i., Královopolská 135, 61265, Brno, Czech Republic
| | - Jiří Fajkus
- Mendel Centre for Plant Genomics and Proteomics, CEITEC - Central European Institute of Technology, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic.
- Laboratory of Functional Genomics and Proteomics, National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic.
- Institute of Biophysics, Academy of Sciences of the Czech Republic, v.v.i., Královopolská 135, 61265, Brno, Czech Republic.
| |
Collapse
|
23
|
Loza-Muller L, Rodríguez-Corona U, Sobol M, Rodríguez-Zapata LC, Hozak P, Castano E. Fibrillarin methylates H2A in RNA polymerase I trans-active promoters in Brassica oleracea. FRONTIERS IN PLANT SCIENCE 2015; 6:976. [PMID: 26594224 PMCID: PMC4635213 DOI: 10.3389/fpls.2015.00976] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2015] [Accepted: 10/26/2015] [Indexed: 05/24/2023]
Abstract
Fibrillarin is a well conserved methyltransferase involved in several if not all of the more than 100 methylations sites in rRNA which are essential for proper ribosome function. It is mainly localized in the nucleoli and Cajal bodies inside the cell nucleus where it exerts most of its functions. In plants, fibrillarin binds directly the guide RNA together with Nop56, Nop58, and 15.5ka proteins to form a snoRNP complex that selects the sites to be methylated in pre-processing of ribosomal RNA. Recently, the yeast counterpart NOP1 was found to methylate histone H2A in the nucleolar regions. Here we show that plant fibrillarin can also methylate histone H2A. In Brassica floral meristem cells the methylated histone H2A is mainly localized in the nucleolus but unlike yeast or human cells it also localize in the periphery of the nucleus. In specialized transport cells the pattern is altered and it exhibits a more diffuse staining in the nucleus for methylated histone H2A as well as for fibrillarin. Here we also show that plant fibrillarin is capable of interacting with H2A and carry out its methylation in the rDNA promoter.
Collapse
Affiliation(s)
- Lloyd Loza-Muller
- Unidad de Bioquímica y Biología Molecular de Plantas, Centro de Investigación Científica de YucatánMérida, Mexico
| | - Ulises Rodríguez-Corona
- Unidad de Bioquímica y Biología Molecular de Plantas, Centro de Investigación Científica de YucatánMérida, Mexico
| | - Margarita Sobol
- Department of Biology of the Cell Nucleus, Institute of Molecular Genetics of the Academy of Sciences of the Czech Republic, v.v.i.Prague, Czech Republic
| | | | - Pavel Hozak
- Department of Biology of the Cell Nucleus, Institute of Molecular Genetics of the Academy of Sciences of the Czech Republic, v.v.i.Prague, Czech Republic
| | - Enrique Castano
- Unidad de Bioquímica y Biología Molecular de Plantas, Centro de Investigación Científica de YucatánMérida, Mexico
| |
Collapse
|
24
|
Rodriguez-Corona U, Sobol M, Rodriguez-Zapata LC, Hozak P, Castano E. Fibrillarin from Archaea to human. Biol Cell 2015; 107:159-74. [PMID: 25772805 DOI: 10.1111/boc.201400077] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2014] [Accepted: 03/05/2015] [Indexed: 12/19/2022]
Abstract
Fibrillarin is an essential protein that is well known as a molecular marker of transcriptionally active RNA polymerase I. Fibrillarin methyltransferase activity is the primary known source of methylation for more than 100 methylated sites involved in the first steps of preribosomal processing and required for structural ribosome stability. High expression levels of fibrillarin have been observed in several types of cancer cells, particularly when p53 levels are reduced, because p53 is a direct negative regulator of fibrillarin transcription. Here, we show fibrillarin domain conservation, structure and interacting molecules in different cellular processes as well as with several viral proteins during virus infection.
Collapse
Affiliation(s)
- Ulises Rodriguez-Corona
- Unidad de Bioquímica y Biología molecular de plantas, Centro de Investigación Científica de Yucatán, Colonia Chuburná de Hidalgo, Mérida, Yucatan, Mexico
| | - Margarita Sobol
- Department of Biology of the Cell Nucleus, Institute of Molecular Genetics of the Academy of Sciences of the Czech Republic, Prague 14220, Czech Republic
| | - Luis Carlos Rodriguez-Zapata
- Unidad de Biotecnología, Centro de Investigación Científica de Yucatán, Colonia Chuburná de Hidalgo, Mérida, Yucatan, Mexico
| | - Pavel Hozak
- Department of Biology of the Cell Nucleus, Institute of Molecular Genetics of the Academy of Sciences of the Czech Republic, Prague 14220, Czech Republic
| | - Enrique Castano
- Unidad de Bioquímica y Biología molecular de plantas, Centro de Investigación Científica de Yucatán, Colonia Chuburná de Hidalgo, Mérida, Yucatan, Mexico
| |
Collapse
|
25
|
Engelke R, Riede J, Hegermann J, Wuerch A, Eimer S, Dengjel J, Mittler G. The Quantitative Nuclear Matrix Proteome as a Biochemical Snapshot of Nuclear Organization. J Proteome Res 2014; 13:3940-56. [DOI: 10.1021/pr500218f] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Rudolf Engelke
- Max Planck Institute of Immunobiology and Epigenetics, Stübeweg 51, 79108 Freiburg, Germany
| | - Julia Riede
- Freiburg
Institute for Advanced Studies, School of Life Sciences − LifeNet, University of Freiburg, Albertstrasse 19, 79104 Freiburg, Germany
- Center
for Biological Systems Analysis, University of Freiburg, Habsburgerstrasse
49, 79104 Freiburg, Germany
| | - Jan Hegermann
- European Neuroscience Institute and Center for Molecular Physiology of the Brain (CMPB), 37077 Göttingen, Germany
| | - Andreas Wuerch
- Max Planck Institute of Immunobiology and Epigenetics, Stübeweg 51, 79108 Freiburg, Germany
| | - Stefan Eimer
- European Neuroscience Institute and Center for Molecular Physiology of the Brain (CMPB), 37077 Göttingen, Germany
| | - Joern Dengjel
- Freiburg
Institute for Advanced Studies, School of Life Sciences − LifeNet, University of Freiburg, Albertstrasse 19, 79104 Freiburg, Germany
- Center
for Biological Systems Analysis, University of Freiburg, Habsburgerstrasse
49, 79104 Freiburg, Germany
| | - Gerhard Mittler
- Max Planck Institute of Immunobiology and Epigenetics, Stübeweg 51, 79108 Freiburg, Germany
- BIOSS,
Center for Biological Signalling Studies, University of Freiburg, Schänzlestrasse 18, 79104 Freiburg, Germany
| |
Collapse
|
26
|
Peng Y, Yu G, Tian S, Li H. Co-expression and co-purification of archaeal and eukaryal box C/D RNPs. PLoS One 2014; 9:e103096. [PMID: 25078083 PMCID: PMC4117494 DOI: 10.1371/journal.pone.0103096] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2014] [Accepted: 06/27/2014] [Indexed: 11/18/2022] Open
Abstract
Box C/D ribonucleoprotein particles (RNPs) are 2'-O-methylation enzymes required for maturation of ribosomal and small nuclear RNA. Previous biochemical and structural studies of the box C/D RNPs were limited by the unavailability of purified intact RNPs. We developed a bacterial co-expression strategy based on the combined use of a multi-gene expression system and a tRNA-scaffold construct that allowed the expression and purification of homogeneous archaeal and human box C/D RNPs. While the co-expressed and co-purified archaeal box C/D RNP was found to be fully active in a 2'-O-methylation assay, the intact human U14 box C/D RNP showed no detectable catalytic activity, consistent with the earlier findings that assembly of eukaryotic box C/D RNPs is nonspontaneous and requires additional protein factors. Our systems provide a means for further biochemical and structural characterization of box C/D RNPs and their assembly factors.
Collapse
Affiliation(s)
- Yu Peng
- Institute of Molecular Biophysics, Florida State University, Tallahassee, Florida, United States of America
| | - Ge Yu
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida, United States of America
| | - Shaoxiong Tian
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida, United States of America
| | - Hong Li
- Institute of Molecular Biophysics, Florida State University, Tallahassee, Florida, United States of America
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida, United States of America
- * E-mail:
| |
Collapse
|
27
|
Crowded chromatin is not sufficient for heterochromatin formation and not required for its maintenance. J Struct Biol 2013; 184:445-53. [PMID: 24145303 DOI: 10.1016/j.jsb.2013.10.004] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2013] [Revised: 09/30/2013] [Accepted: 10/03/2013] [Indexed: 11/22/2022]
Abstract
In contrast to cytoplasmic organelles, which are usually separated from the rest of the cell by phospholipid membranes, nuclear compartments are readily accessible to diffusing proteins and must rely on different mechanisms to maintain their integrity. Specific interactions between scaffolding proteins are known to have important roles for the formation and maintenance of nuclear structures. General physical mechanisms such as molecular crowding, phase separation or colloidal behavior have also been suggested, but their physiological significance remains uncertain. For macromolecular crowding, a role in the maintenance of nucleoli and promyelocytic leukemia (PML) nuclear bodies has been shown. Here, we tested whether a modulation of the compaction state of chromatin, which directly influences the local crowding state, has an impact on the formation and maintenance of densely packed heterochromatin. By osmotic perturbations, we could modify the packing state of chromatin in a controlled manner and show that chromatin compaction, which is associated with increased crowding conditions, is not, per se, sufficient to initiate the formation of new bona fide heterochromatin structures nor is it necessary to maintain already established heterochromatin domains. In consequence, if an increase in crowding induced by chromatin compaction maybe an early step in heterochromatin formation, specific protein-protein interactions are nevertheless required to make heterochromatin long lasting and independent of the crowding state.
Collapse
|
28
|
Rakitina DV, Taliansky M, Brown JWS, Kalinina NO. Two RNA-binding sites in plant fibrillarin provide interactions with various RNA substrates. Nucleic Acids Res 2011; 39:8869-80. [PMID: 21785141 PMCID: PMC3203579 DOI: 10.1093/nar/gkr594] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Fibrillarin, one of the major proteins of the nucleolus, plays several essential roles in ribosome biogenesis including pre-rRNA processing and 2′-O-ribose methylation of rRNA and snRNAs. Recently, it has been shown that fibrillarin plays a role in virus infections and is associated with viral RNPs. Here, we demonstrate the ability of recombinant fibrillarin 2 from Arabidopsis thaliana (AtFib2) to interact with RNAs of different lengths and types including rRNA, snoRNA, snRNA, siRNA and viral RNAs in vitro. Our data also indicate that AtFib2 possesses two RNA-binding sites in the central (138–179 amino acids) and C-terminal (225–281 amino acids) parts of the protein, respectively. The conserved GCVYAVEF octamer does not bind RNA directly as suggested earlier, but may assist with the proper folding of the central RNA-binding site.
Collapse
Affiliation(s)
- D. V. Rakitina
- Department of Virology and A.N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow 119991, Russia, The James Hutton Institute, Invergowrie, Dundee, DD2 5DA, UK and Plant Sciences Division, University of Dundee, DD2 5DA, UK
| | - Michael Taliansky
- Department of Virology and A.N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow 119991, Russia, The James Hutton Institute, Invergowrie, Dundee, DD2 5DA, UK and Plant Sciences Division, University of Dundee, DD2 5DA, UK
- *To whom correspondence should be addressed. Tel: +44(0)1382562731; Fax: +44 (0)1382 562426;
| | - J. W. S. Brown
- Department of Virology and A.N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow 119991, Russia, The James Hutton Institute, Invergowrie, Dundee, DD2 5DA, UK and Plant Sciences Division, University of Dundee, DD2 5DA, UK
| | - N. O. Kalinina
- Department of Virology and A.N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow 119991, Russia, The James Hutton Institute, Invergowrie, Dundee, DD2 5DA, UK and Plant Sciences Division, University of Dundee, DD2 5DA, UK
| |
Collapse
|
29
|
Yoshikawa H, Komatsu W, Hayano T, Miura Y, Homma K, Izumikawa K, Ishikawa H, Miyazawa N, Tachikawa H, Yamauchi Y, Isobe T, Takahashi N. Splicing factor 2-associated protein p32 participates in ribosome biogenesis by regulating the binding of Nop52 and fibrillarin to preribosome particles. Mol Cell Proteomics 2011; 10:M110.006148. [PMID: 21536856 DOI: 10.1074/mcp.m110.006148] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Ribosome biogenesis starts with transcription of the large ribosomal RNA precursor (47S pre-rRNA), which soon combines with numerous factors to form the 90S pre-ribosome in the nucleolus. Although the subsequent separation of the pre-90S particle into pre-40S and pre-60S particles is critical for the production process of mature small and large ribosomal subunits, its molecular mechanisms remain undetermined. Here, we present evidence that p32, fibrillarin (FBL), and Nop52 play key roles in this separation step. Mass-based analyses combined with immunoblotting showed that p32 associated with 155 proteins including 31 rRNA-processing factors (of which nine were components of small subunit processome, and six were those of RIX1 complex), 13 chromatin remodeling components, and six general transcription factors required for RNA polymerase III-mediated transcription. Of these, a late rRNA-processing factor Nop52 interacted directly with p32. Immunocytochemical analyses demonstrated that p32 colocalized with an early rRNA-processing factor FBL or Nop52 in the nucleolus and Cajal bodies, but was excluded from the nucleolus after actinomycin D treatment. p32 was present in the pre-ribosomal fractions prepared by cell fractionation or separated by ultracentrifugation of the nuclear extract. p32 also associated with pre-rRNAs including 47S/45S and 32S pre-rRNAs. Furthermore, knockdown of p32 with a small interfering RNA slowed the early processing from 47S/45S pre-rRNAs to 18S rRNA and 32S pre-rRNA. Finally, Nop52 was found to compete with FBL for binding to p32 probably in the nucleolus. Given the fact that FBL and Nop52 are associated with pre-ribosome particles distinctly different from each other, we suggest that p32 is a new rRNA maturation factor involved in the remodeling from pre-90S particles to pre-40S and pre-60S particles that requires the exchange of FBL for Nop52.
Collapse
Affiliation(s)
- Harunori Yoshikawa
- Department of Applied Life Science, United Graduate School of Agriculture, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu-shi, Tokyo 183-8509, Japan
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
30
|
Barygina VV, Veiko VP, Zatsepina OV. Analysis of nucleolar protein fibrillarin mobility and functional state in living HeLa cells. BIOCHEMISTRY (MOSCOW) 2010; 75:979-88. [PMID: 21073418 DOI: 10.1134/s0006297910080055] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Fibrillarin is an evolutionarily-conserved and obligatory protein component of eukaryotic cell nucleoli involved in pre-rRNA processing and methylation. In vertebrates the fibrillarin molecule contains two cysteine residues (Cys99 and Cys268) whose sulfhydryl groups are able to establish intramolecular -S-S- bridges. However, the functional state of fibrillarin with reduced or oxidized thiol groups is still practically unstudied. Besides, there are no data in the literature concerning existence of the -S-S- fibrillarin form in human cells. To answer these questions, we used plasmids encoding native human fibrillarin and its mutant form devoid of cysteine residues (fibrillarinC99/268S) fused with EGFP for temporary transfection of HeLa cells. The mobile fraction localizing the enzymatically active protein molecules and the fluorescence half-recovery time characterizing the rate of enzymatic reactions were determined by the FRAP technique using a confocal laser scanning microscope. Measurements were carried out at 37 and 27°C. The results show that the fibrillarin pool in HeLa cells includes two protein forms, with reduced SH groups and with oxidized SH groups forming intramolecular -S-S- bridges between Cys99 and Cys268. However, the absence of Cys99 and Cys268 has no effect on intracellular localization of fibrillarin and its main dynamic parameters. The human fibrillarin form without disulfide bridges is included into the mobile protein fraction and is consistent with its functionally active state.
Collapse
Affiliation(s)
- V V Barygina
- Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, 117997, Russia.
| | | | | |
Collapse
|
31
|
Abstract
The nucleus is unique amongst cellular organelles in that it contains a myriad of discrete suborganelles. These nuclear bodies are morphologically and molecularly distinct entities, and they host specific nuclear processes. Although the mode of biogenesis appears to differ widely between individual nuclear bodies, several common design principles are emerging, particularly, the ability of nuclear bodies to form de novo, a role of RNA as a structural element and self-organization as a mode of formation. The controlled biogenesis of nuclear bodies is essential for faithful maintenance of nuclear architecture during the cell cycle and is an important part of cellular responses to intra- and extracellular events.
Collapse
Affiliation(s)
- Miroslav Dundr
- Department of Cell Biology, Rosalind Franklin University of Medicine and Science, North Chicago, Ilinois 60064, USA.
| | | |
Collapse
|
32
|
Taliansky ME, Brown JWS, Rajamäki ML, Valkonen JPT, Kalinina NO. Involvement of the plant nucleolus in virus and viroid infections: parallels with animal pathosystems. Adv Virus Res 2010; 77:119-58. [PMID: 20951872 PMCID: PMC7149663 DOI: 10.1016/b978-0-12-385034-8.00005-3] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The nucleolus is a dynamic subnuclear body with roles in ribosome subunit biogenesis, mediation of cell-stress responses, and regulation of cell growth. An increasing number of reports reveal that similar to the proteins of animal viruses, many plant virus proteins localize in the nucleolus to divert host nucleolar proteins from their natural functions in order to exert novel role(s) in the virus infection cycle. This chapter will highlight studies showing how plant viruses recruit nucleolar functions to facilitate virus translation and replication, virus movement and assembly of virus-specific ribonucleoprotein (RNP) particles, and to counteract plant host defense responses. Plant viruses also provide a valuable tool to gain new insights into novel nucleolar functions and processes. Investigating the interactions between plant viruses and the nucleolus will facilitate the design of novel strategies to control plant virus infections.
Collapse
Affiliation(s)
- M E Taliansky
- Scottish Crop Research Institute, Invergowrie, Dundee, United Kingdom
| | | | | | | | | |
Collapse
|
33
|
Abstract
The Cajal body (CB) is a nuclear organelle present in all eukaryotes that have been carefully studied. It is identified by the signature protein coilin and by CB-specific RNAs (scaRNAs). CBs contain high concentrations of splicing small nuclear ribonucleoproteins (snRNPs) and other RNA processing factors, suggesting that they are sites for assembly and/or posttranscriptional modification of the splicing machinery of the nucleus. The histone locus body (HLB) contains factors required for processing histone pre-mRNAs. As its name implies, the HLB is associated with the genes that code for histones, suggesting that it may function to concentrate processing factors at their site of action. CBs and HLBs are present throughout the interphase of the cell cycle, but disappear during mitosis. The biogenesis of CBs shows the features of a self-organizing structure.
Collapse
Affiliation(s)
- Zehra Nizami
- Department of Embryology, Carnegie Institution for Science, Baltimore, Maryland 21218, USA
| | | | | |
Collapse
|
34
|
Brand P, Lenser T, Hemmerich P. Assembly dynamics of PML nuclear bodies in living cells. PMC BIOPHYSICS 2010; 3:3. [PMID: 20205709 PMCID: PMC2854101 DOI: 10.1186/1757-5036-3-3] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/15/2009] [Accepted: 03/05/2010] [Indexed: 01/17/2023]
Abstract
The mammalian cell nucleus contains a variety of organelles or nuclear bodies which contribute to key nuclear functions. Promyelocytic leukemia nuclear bodies (PML NBs) are involved in the regulation of apoptosis, antiviral responses, the DNA damage response and chromatin structure, but their precise biochemical function in these nuclear pathways is unknown. One strategy to tackle this problem is to assess the biophysical properties of the component parts of these macromolecular assemblies in living cells. In this study we determined PML NB assembly dynamics by live cell imaging, combined with mathematical modeling. For the first time, dynamics of PML body formation were measured in cells lacking endogenous PML. We show that all six human nuclear PML isoforms are able to form nuclear bodies in PML negative cells. All isoforms exhibit individual exchange rates at NBs in PML positive cells but PML I, II, III and IV are static at nuclear bodies in PML negative cells, suggesting that these isoforms require additional protein partners for efficient exchange. PML V turns over at PML Nbs very slowly supporting the idea of a structural function for this isoform. We also demonstrate that SUMOylation of PML at Lysine positions K160 and/or K490 are required for nuclear body formation in vivo.We propose a model in which the isoform specific residence times of PML provide both, structural stability to function as a scaffold and flexibility to attract specific nuclear proteins for efficient biochemical reactions at the surface of nuclear bodies. MCS code: 92C37
Collapse
Affiliation(s)
- Peter Brand
- Leibniz-Institute of Age Research, Fritz-Lipman-Institute, Beutenbergstr, 11, 07745 Jena, Germany.
| | | | | |
Collapse
|
35
|
Dvorácková M, Rossignol P, Shaw PJ, Koroleva OA, Doonan JH, Fajkus J. AtTRB1, a telomeric DNA-binding protein from Arabidopsis, is concentrated in the nucleolus and shows highly dynamic association with chromatin. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2010; 61:637-49. [PMID: 19947985 DOI: 10.1111/j.1365-313x.2009.04094.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
AtTRB1, 2 and 3 are members of the SMH (single Myb histone) protein family, which comprises double-stranded DNA-binding proteins that are specific to higher plants. They are structurally conserved, containing a Myb domain at the N-terminus, a central H1/H5-like domain and a C-terminally located coiled-coil domain. AtTRB1, 2 and 3 interact through their Myb domain specifically with telomeric double-stranded DNA in vitro, while the central H1/H5-like domain interacts non-specifically with DNA sequences and mediates protein-protein interactions. Here we show that AtTRB1, 2 and 3 preferentially localize to the nucleus and nucleolus during interphase. Both the central H1/H5-like domain and the Myb domain from AtTRB1 can direct a GFP fusion protein to the nucleus and nucleolus. AtTRB1-GFP localization is cell cycle-regulated, as the level of nuclear-associated GFP diminishes during mitotic entry and GFP progressively re-associates with chromatin during anaphase/telophase. Using fluorescence recovery after photobleaching and fluorescence loss in photobleaching, we determined the dynamics of AtTRB1 interactions in vivo. The results reveal that AtTRB1 interaction with chromatin is regulated at two levels at least, one of which is coupled with cell-cycle progression, with the other involving rapid exchange.
Collapse
Affiliation(s)
- Martina Dvorácková
- Department of Cell and Developmental Biology, John Innes Centre, Colney Lane, Norwich NR4 7UH, UK
| | | | | | | | | | | |
Collapse
|
36
|
Cisterna B, Biggiogera M. Ribosome biogenesis: from structure to dynamics. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2010; 284:67-111. [PMID: 20875629 DOI: 10.1016/s1937-6448(10)84002-x] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
In this chapter we describe the status of the research concerning the nucleolus, the major nuclear body. The nucleolus has been recognized as a dynamic organelle with many more functions than one could imagine. In fact, in addition to its fundamental role in the biogenesis of preribosomes, the nucleolus takes part in many other cellular processes and functions, such as the cell-cycle control and the p53 pathway: the direct or indirect involvement of the nucleolus in these various processes makes it sensitive to their alteration. Moreover, it is worth noting that the different nucleolar factors participating to independent mechanisms show different dynamics of association/disassociation with the nucleolar body.
Collapse
Affiliation(s)
- Barbara Cisterna
- Laboratory of Cell Biology and Neurobiology, Department of Animal Biology, University of Pavia, Pavia, Italy
| | | |
Collapse
|
37
|
Hoffmann MH, Trembleau S, Muller S, Steiner G. Nucleic acid-associated autoantigens: pathogenic involvement and therapeutic potential. J Autoimmun 2009; 34:J178-206. [PMID: 20031372 DOI: 10.1016/j.jaut.2009.11.013] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Autoimmunity to ubiquitously expressed macromolecular nucleic acid-protein complexes such as the nucleosome or the spliceosome is a characteristic feature of systemic autoimmune diseases. Disease-specificity and/or association with clinical features of some of these autoimmune responses suggest pathogenic involvement which, however, has been proven in only a few cases so far. Although the mechanisms leading to autoimmunity against nucleic acid-containing complexes are still far from being fully understood, there is increasing experimental evidence that the nucleic acid component may act as a co-stimulator or adjuvans via activation of nucleic acid-binding receptor systems such as Toll-like receptors in antigen-presenting cells. Dysregulated apoptosis and inappropriate stimulation of nucleic acid-sensing receptors may lead to loss of tolerance against the protein components of such complexes, activation of autoreactive T cells and formation of autoantibodies. This has been demonstrated to occur in systemic lupus erythematosus and seems to represent a general mechanism that may be crucial for the development of systemic autoimmune diseases. This review provides a comprehensive overview of the most thoroughly-characterized nucleic acid-associated autoantigens, describing their structure and biological function, as well as the nature and pathogenic importance of the reactivities directed against them. Furthermore, recent advances in immunotherapy such as antigen-specific approaches targeted at nucleic acid-binding antigens are discussed.
Collapse
Affiliation(s)
- Markus H Hoffmann
- Division of Rheumatology, Internal Medicine III, Medical University of Vienna, Waehringer Guertel 18-20, A-1090 Vienna, Austria
| | | | | | | |
Collapse
|
38
|
Brouwer AK, Schimmel J, Wiegant JC, Vertegaal AC, Tanke HJ, Dirks RW. Telomeric DNA mediates de novo PML body formation. Mol Biol Cell 2009; 20:4804-15. [PMID: 19793919 PMCID: PMC2777109 DOI: 10.1091/mbc.e09-04-0309] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2009] [Revised: 08/12/2009] [Accepted: 09/21/2009] [Indexed: 11/11/2022] Open
Abstract
The cell nucleus harbors a variety of different bodies that vary in number, composition, and size. Although these bodies coordinate important nuclear processes, little is known about how they are formed. Among the most intensively studied bodies in recent years is the PML body. These bodies have been implicated in gene regulation and other cellular processes and are disrupted in cells from patients suffering from acute promyelocytic leukemia. Using live cell imaging microscopy and immunofluorescence, we show in several cell types that PML bodies are formed at telomeric DNA during interphase. Recent studies revealed that both SUMO modification sites and SUMO interaction motifs in the promyelocytic leukemia (PML) protein are required for PML body formation. We show that SMC5, a component of the SUMO ligase MMS21-containing SMC5/6 complex, localizes temporarily at telomeric DNA during PML body formation, suggesting a possible role for SUMO in the formation of PML bodies at telomeric DNA. Our data identify a novel role of telomeric DNA during PML body formation.
Collapse
Affiliation(s)
- Anneke K. Brouwer
- *Department of Molecular Cell Biology, Leiden University Medical Center, 2300 RC Leiden, The Netherlands
| | - Joost Schimmel
- *Department of Molecular Cell Biology, Leiden University Medical Center, 2300 RC Leiden, The Netherlands
| | - Joop C.A.G. Wiegant
- *Department of Molecular Cell Biology, Leiden University Medical Center, 2300 RC Leiden, The Netherlands
| | - Alfred C.O. Vertegaal
- *Department of Molecular Cell Biology, Leiden University Medical Center, 2300 RC Leiden, The Netherlands
| | - Hans J. Tanke
- *Department of Molecular Cell Biology, Leiden University Medical Center, 2300 RC Leiden, The Netherlands
| | - Roeland W. Dirks
- *Department of Molecular Cell Biology, Leiden University Medical Center, 2300 RC Leiden, The Netherlands
| |
Collapse
|
39
|
Lechertier T, Grob A, Hernandez-Verdun D, Roussel P. Fibrillarin and Nop56 interact before being co-assembled in box C/D snoRNPs. Exp Cell Res 2009; 315:928-42. [PMID: 19331828 DOI: 10.1016/j.yexcr.2009.01.016] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2008] [Revised: 12/12/2008] [Accepted: 01/16/2009] [Indexed: 11/16/2022]
Abstract
Small nucleolar RNAs play crucial roles in ribosome biogenesis. They guide folding, site-specific nucleotide modifications and participate in cleavage of precursor ribosomal RNAs. To better understand how the biogenesis of the box C/D small nucleolar RNPs (snoRNPs) occur in a cellular context, we used a new approach based on the possibility of relocalizing a given nuclear complex by adding an affinity tag for B23 to one component of this complex. We selectively delocalized each core box C/D protein, namely 15.5kD, Nop56, Nop58 and fibrillarin, and analyzed the effect of such changes on other components of the box C/D snoRNPs. We show that modifying the localization and the mobility of core box C/D proteins impairs their association with box C/D snoRNPs. In addition, we demonstrate that fibrillarin and Nop56 directly interact in vivo. This interaction, indispensable for the association of both proteins with the box C/D snoRNPs, does not involve the glycine- and arginine-rich domain or the RNA-binding domain but the alpha-helix domain of fibrillarin. In addition, no RNA seems required to maintain fibrillarin-Nop56 interaction.
Collapse
Affiliation(s)
- Tanguy Lechertier
- Institut Jacques Monod, UMR 7592 CNRS/Universités Paris 6 et 7, 2 Place Jussieu, 75251 Paris Cedex 05, France
| | | | | | | |
Collapse
|
40
|
Kim J, Kwon D, Lee J, Pasquier H, Grailhe R. The use of Cyan Fluorescent Protein variants with a distinctive lifetime signature. MOLECULAR BIOSYSTEMS 2008; 5:151-3. [PMID: 19156260 DOI: 10.1039/b815445g] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The use of Cyan Fluorescent Proteins, with a distinctive lifetime signature, opens up new alternatives to track and semi-quantify the relative expression of proteins in vivo using a single excitation source and emission channel.
Collapse
Affiliation(s)
- Jiho Kim
- Institut Pasteur Korea, 39-1 Hawolgok-dong, Seoul 136-791, South Korea
| | | | | | | | | |
Collapse
|
41
|
Dundr M, Misteli T. Measuring dynamics of nuclear proteins by photobleaching. ACTA ACUST UNITED AC 2008; Chapter 13:Unit 13.5. [PMID: 18228420 DOI: 10.1002/0471143030.cb1305s18] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The mobility of nuclear proteins can be studied by photobleaching techniques. The three main advantages of photobleaching are fast experimental turn around, good spatial and temporal resolution, and the ability to measure kinetics inside of living cells. The main disadvantage of these techniques is the requirement for fluorescently tagged proteins that have rigorously tested to ensure it has the same properties and function as its native counterpart. Three major methods of photobleaching microscopy are described: fluorescence recovery after photobleaching (FRAP), fluorescence loss in photobleaching (FLIP), and inverse fluorescence recovery after photobleaching (iFRAP). Each of these techniques has characteristics permitting the determination of distinct parameters of protein behavior in vivo.
Collapse
|
42
|
Carneiro T, Carvalho C, Braga J, Rino J, Milligan L, Tollervey D, Carmo-Fonseca M. Inactivation of cleavage factor I components Rna14p and Rna15p induces sequestration of small nucleolar ribonucleoproteins at discrete sites in the nucleus. Mol Biol Cell 2008; 19:1499-508. [PMID: 18234838 DOI: 10.1091/mbc.e07-10-1015] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Small nucleolar RNAs (snoRNAs) associate with specific proteins forming small nucleolar ribonucleoprotein (snoRNP) particles, which are essential for ribosome biogenesis. The snoRNAs are transcribed, processed, and assembled in snoRNPs in the nucleoplasm. Mature particles are then transported to the nucleolus. In yeast, 3'-end maturation of snoRNAs involves the activity of Rnt1p endonuclease and cleavage factor IA (CFIA). We report that after inhibition of CFIA components Rna14p and Rna15p, the snoRNP proteins Nop1p, Nop58p, and Gar1p delocalize from the nucleolus and accumulate in discrete nucleoplasmic foci. The U14 snoRNA, but not U3 snoRNA, similarly redistributes from the nucleolus to the nucleoplasmic foci. Simultaneous depletion of either Rna14p or Rna15p and the nuclear exosome component Rrp6p induces accumulation of poly(A)(+) RNA at the snoRNP-containing foci. We propose that the foci detected after CFIA inactivation correspond to quality control centers in the nucleoplasm.
Collapse
Affiliation(s)
- Tiago Carneiro
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, 1649-028 Lisboa, Portugal
| | | | | | | | | | | | | |
Collapse
|
43
|
Platani M, Lamond AI. Nuclear organisation and subnuclear bodies. PROGRESS IN MOLECULAR AND SUBCELLULAR BIOLOGY 2008; 35:1-22. [PMID: 15113077 DOI: 10.1007/978-3-540-74266-1_1] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Affiliation(s)
- Melpomeni Platani
- Wellcome Trust Biocentre, MSI/WTB Complex, DD1 5EH, Dundee, Scotland, United Kingdom
| | | |
Collapse
|
44
|
Sirri V, Urcuqui-Inchima S, Roussel P, Hernandez-Verdun D. Nucleolus: the fascinating nuclear body. Histochem Cell Biol 2007; 129:13-31. [PMID: 18046571 PMCID: PMC2137947 DOI: 10.1007/s00418-007-0359-6] [Citation(s) in RCA: 295] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/06/2007] [Indexed: 11/30/2022]
Abstract
Nucleoli are the prominent contrasted structures of the cell nucleus. In the nucleolus, ribosomal RNAs are synthesized, processed and assembled with ribosomal proteins. RNA polymerase I synthesizes the ribosomal RNAs and this activity is cell cycle regulated. The nucleolus reveals the functional organization of the nucleus in which the compartmentation of the different steps of ribosome biogenesis is observed whereas the nucleolar machineries are in permanent exchange with the nucleoplasm and other nuclear bodies. After mitosis, nucleolar assembly is a time and space regulated process controlled by the cell cycle. In addition, by generating a large volume in the nucleus with apparently no RNA polymerase II activity, the nucleolus creates a domain of retention/sequestration of molecules normally active outside the nucleolus. Viruses interact with the nucleolus and recruit nucleolar proteins to facilitate virus replication. The nucleolus is also a sensor of stress due to the redistribution of the ribosomal proteins in the nucleoplasm by nucleolus disruption. The nucleolus plays several crucial functions in the nucleus: in addition to its function as ribosome factory of the cells it is a multifunctional nuclear domain, and nucleolar activity is linked with several pathologies. Perspectives on the evolution of this research area are proposed.
Collapse
Affiliation(s)
- Valentina Sirri
- Nuclei and Cell Cycle, CNRS, Université Paris VI, Université Paris VII, Institut Jacques Monod, 2 place Jussieu, 75251 Paris Cedex 05, France
| | - Silvio Urcuqui-Inchima
- Nuclei and Cell Cycle, CNRS, Université Paris VI, Université Paris VII, Institut Jacques Monod, 2 place Jussieu, 75251 Paris Cedex 05, France
- Grupo de Inmunovirología, Biogénesis, Universidad de Antioquia, Calle 62 No. 52-59, Medellin, Colombia
| | - Pascal Roussel
- Nuclei and Cell Cycle, CNRS, Université Paris VI, Université Paris VII, Institut Jacques Monod, 2 place Jussieu, 75251 Paris Cedex 05, France
| | - Danièle Hernandez-Verdun
- Nuclei and Cell Cycle, CNRS, Université Paris VI, Université Paris VII, Institut Jacques Monod, 2 place Jussieu, 75251 Paris Cedex 05, France
| |
Collapse
|
45
|
Stoldt S, Wenzel D, Schulze E, Doenecke D, Happel N. G1 phase-dependent nucleolar accumulation of human histone H1x. Biol Cell 2007; 99:541-52. [PMID: 17868027 DOI: 10.1042/bc20060117] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
BACKGROUND INFORMATION H1 histones are a protein family comprising several subtypes. Although specific functions of the individual subtypes could not be determined so far, differential roles are indicated by varied nuclear distributions as well as differential expression patterns of the H1 subtypes. Although the group of replication-dependent H1 subtypes is synthesized during S phase, the replacement H1 subtype, H1 degrees , is also expressed in a replication-independent manner in non-proliferating cells. Recently we showed, by protein biochemical analysis, that the ubiquitously expressed subtype H1x is enriched in the micrococcal nuclease-resistant part of chromatin and that, although it shares common features with H1 degrees , its expression is differentially regulated, since, in contrast to H1 degrees , growth arrest or induction of differentiation did not induce an accumulation of H1x. RESULTS In the present study, we show that H1x exhibits a cell-cycle-dependent change of its nuclear distribution. This H1 subtype showed a nucleolar accumulation during the G(1) phase, and it was evenly distributed in the nucleus during S phase and G(2). Immunocytochemical analysis of the intranucleolar distribution of H1x indicated that it is located mainly in the condensed nucleolar chromatin. In addition, we demonstrate that the amount of H1x protein remained nearly unchanged during S phase progression, which is in contrast to the replication-dependent subtypes. CONCLUSION These results suggest that the differential localization of H1x provides a mechanism for a control of H1x activity by means of shuttling between nuclear subcompartments instead of a controlled turnover of the protein.
Collapse
Affiliation(s)
- Stefan Stoldt
- Institute for Biochemistry and Molecular Cell Biology, University of Göttingen, Humboldtallee 23, 37073 Göttingen, Germany
| | | | | | | | | |
Collapse
|
46
|
A stochastic view of spliceosome assembly and recycling in the nucleus. PLoS Comput Biol 2007; 3:2019-31. [PMID: 17967051 PMCID: PMC2041977 DOI: 10.1371/journal.pcbi.0030201] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2007] [Accepted: 09/04/2007] [Indexed: 12/16/2022] Open
Abstract
How splicing factors are recruited to nascent transcripts in the nucleus in order to assemble spliceosomes on newly synthesised pre-mRNAs is unknown. To address this question, we compared the intranuclear trafficking kinetics of small nuclear ribonucleoprotein particles (snRNP) and non-snRNP proteins in the presence and absence of splicing activity. Photobleaching experiments clearly show that spliceosomal proteins move continuously throughout the entire nucleus independently of ongoing transcription or splicing. Using quantitative experimental data, a mathematical model was applied for spliceosome assembly and recycling in the nucleus. The model assumes that splicing proteins move by Brownian diffusion and interact stochastically with binding sites located at different subnuclear compartments. Inhibition of splicing, which reduces the number of pre-mRNA binding sites available for spliceosome assembly, was modeled as a decrease in the on-rate binding constant in the nucleoplasm. Simulation of microscopy experiments before and after splicing inhibition yielded results consistent with the experimental observations. Taken together, our data argue against the view that spliceosomal components are stored in nuclear speckles until a signal triggers their recruitment to nascent transcripts. Rather, the results suggest that splicing proteins are constantly diffusing throughout the entire nucleus and collide randomly and transiently with pre-mRNAs. Understanding the genomic program of an organism requires knowledge of how the information encoded in DNA is processed to generate messenger RNAs that can be translated into proteins. The initial products of gene transcription are extensively modified in the cell nucleus, and a major processing reaction consists of splicing of specific sequences from the middle of the primary transcripts. Splicing is catalyzed by the spliceosome, a large complex composed of five small RNAs and over 100 different proteins. Spliceosomes form anew on primary transcripts and disassemble after splicing, but what triggers the recruitment of individual spliceosomal components to selected gene products is unclear. Here, we have combined imaging and computational approaches to address this question. We obtained quantitative experimental data on the mobility and subnuclear distribution of splicing proteins before and after splicing inhibition, and we applied mathematical models to analyze and interpret the results. We conclude that spliceosomal components do not require a signal in order to be recruited to nascent transcripts. Our results favor the view that splicing proteins are constantly diffusing throughout the entire nucleus and collide randomly and transiently with primary gene products.
Collapse
|
47
|
Alvarez M, Nardocci G, Thiry M, Alvarez R, Reyes M, Molina A, Vera MI. The nuclear phenotypic plasticity observed in fish during rRNA regulation entails Cajal bodies dynamics. Biochem Biophys Res Commun 2007; 360:40-5. [PMID: 17588531 DOI: 10.1016/j.bbrc.2007.05.217] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2007] [Accepted: 05/25/2007] [Indexed: 12/11/2022]
Abstract
Cajal bodies (CBs) are small mobile organelles found throughout the nucleoplasm of animal and plant cells. The dynamics of these organelles involves interactions with the nucleolus. The later has been found to play a substantial role in the compensatory response that evolved in eurythermal fish to adapt to the cyclic seasonal habitat changes, i.e., temperature and photoperiod. Contrary to being constitutive, rRNA synthesis is dramatically regulated between summer and winter, thus affecting ribosomal biogenesis which plays a central role in the acclimatization process. To examine whether CBs, up to now, never described in fish, were also sustaining the phenotypic plasticity observed in nuclei of fish undergoing seasonal acclimatization, we identified these organelles both, by transmission electronic microscopy and immunodetection with the marker protein p80-coilin. We found transcripts in all tissues analyzed. Furthermore we assessed that p80-coilin gene expression was always higher in summer-acclimatized fish when compared to that adapted to the cold season, indicating that p80-coilin expression is modulated upon seasonal acclimatization. Concurrently, CBs were more frequently found in summer-acclimatized carp which suggests that the organization of CBs is involved in adaptive processes and contribute to the phenotypic plasticity of fish cell nuclei observed concomitantly with profound reprogramming of nucleolar components and regulation of ribosomal rRNAs.
Collapse
Affiliation(s)
- Marco Alvarez
- Department of Biological Sciences, Universidad Andres Bello, and Millennium Institute for Fundamental and Applied Biology, Santiago, Chile
| | | | | | | | | | | | | |
Collapse
|
48
|
Sleeman J. A regulatory role for CRM1 in the multi-directional trafficking of splicing snRNPs in the mammalian nucleus. J Cell Sci 2007; 120:1540-50. [PMID: 17405816 DOI: 10.1242/jcs.001529] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Distinct pathways of ribonucleoprotein transport exist within the nucleus, connected to their biogenesis and maturation. These occur despite evidence that the major mechanism for their movement within the nucleus is passive diffusion. Using fusions of Sm proteins to YFP, CFP and photoactivatable GFP, I have demonstrated that pathways with uni-directional bulk flow of complexes can be maintained within the nucleus despite multi-directional exchange of individual complexes. Newly imported splicing small nuclear ribonucleoproteins (snRNPs) exchange between Cajal bodies (CBs) within a nucleus and access the cytoplasm, but are unable to accumulate in speckles. By contrast, snRNPs at steady-state exchange freely in any direction between CBs and speckles, but cannot leave the nucleus. In addition to these surprising qualitative observations in the behaviour of nuclear complexes, sensitive live-cell microscopy techniques can detect subtle quantitative disturbances in nuclear dynamics before they have had an effect on overall nuclear organization. Inhibition of the nuclear export factor, CRM1, using leptomycin B results in a change in the dynamics of interaction of newly imported snRNPs with CBs. Together with the detection of interactions of CRM1 with Sm proteins and the survival of motor neurons (SMN) protein, these studies suggest that the export receptor CRM1 is a key player in the molecular mechanism for maintaining these pathways. Its role in snRNP trafficking, however, appears to be distinct from its previously identified role in small nucleolar RNP (snoRNP) maturation.
Collapse
Affiliation(s)
- Judith Sleeman
- Division of Pathology and Neuroscience, University of Dundee, Ninewells Hospital and Medical School, Dundee DD1 9SY, UK.
| |
Collapse
|
49
|
Lechertier T, Sirri V, Hernandez-Verdun D, Roussel P. A B23-interacting sequence as a tool to visualize protein interactions in a cellular context. J Cell Sci 2006; 120:265-75. [PMID: 17179202 DOI: 10.1242/jcs.03345] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
We report the characterization of a nucleolar localization sequence (NoLS) that targets the green fluorescent protein (GFP) into the granular component (GC) of nucleoli. This NoLS interacts in vitro specifically and directly with the major nucleolar protein B23 and more precisely with the region of B23 including the two acidic stretches. The affinity of NoLS for B23 is stronger than that of the HIV-1 Rev protein in vitro. Moreover, B23-NoLS interaction also occurs in vivo. Indeed, (1) NoLS confers on the GFP the behavior of B23 throughout the cell cycle, (2) the GFP-NoLS fusion and B23 remain colocalized after drug treatments, (3) a selective delocalization of B23 from nucleoli to nucleoplasm induces a concomitent delocalization of the GFP-NoLS fusion, and (4) the fusion of NoLS to fibrillarin makes it possible to colocalize fibrillarin and B23. Interestingly, by fusing NoLS to fibrillarin, both fibrillarin and the fibrillarin partner Nop56 are mislocalized in the GC of nucleoli. Similarly, by fusing the NoLS to MafG, part of the nuclear transcription factor NF-E2 composed of both MafG and p45 NF-E2, NF-E2 is redirected from the nucleoplasm to the nucleoli. Thus, we propose that the NoLS may be used as a tool to visualize and prove protein interactions in a cellular context.
Collapse
Affiliation(s)
- Tanguy Lechertier
- Institut Jacques Monod, UMR 7592 CNRS/Universités Paris 6 et 7, 2 Place Jussieu, 75251 Paris Cedex 05, France
| | | | | | | |
Collapse
|
50
|
Kopp K, Gasiorowski JZ, Chen D, Gilmore R, Norton JT, Wang C, Leary DJ, Chan EKL, Dean DA, Huang S. Pol I transcription and pre-rRNA processing are coordinated in a transcription-dependent manner in mammalian cells. Mol Biol Cell 2006; 18:394-403. [PMID: 17108330 PMCID: PMC1783775 DOI: 10.1091/mbc.e06-03-0249] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Pre-rRNA synthesis and processing are key steps in ribosome biogenesis. Although recent evidence in yeast suggests that these two processes are coupled, the nature of their association is unclear. In this report, we analyze the coordination between rDNA transcription and pre-rRNA processing in mammalian cells. We found that pol I transcription factor UBF interacts with pre-rRNA processing factors as analyzed by immunoprecipitations, and the association depends on active rRNA synthesis. In addition, injections of plasmids containing the human rDNA promoter and varying lengths of 18S rDNA into HeLa nuclei show that pol I transcription machinery can be recruited to rDNA promoters regardless of the product that is transcribed, whereas subgroups of pre-rRNA processing factors are recruited to plasmids only when specific pre-rRNA fragments are produced. Our observations suggest a model for sequential recruitment of pol I transcription factors and pre-rRNA processing factors to elongating pre-rRNA on an as-needed basis rather than corecruitment to sites of active transcription.
Collapse
Affiliation(s)
- K Kopp
- Department of Cell and Molecular Biology, Division of Pulmonary and Critical Care Medicine, Feinberg School of Medicine Northwestern University, Chicago, IL 60611, USA
| | | | | | | | | | | | | | | | | | | |
Collapse
|