1
|
Andraszek K, Gryzińska M, Danielewicz A, Batkowska J, Smalec E. Age-dependent stability of nucleoli and global DNA methylation level in spermatocytes of the domestic horse (Equus caballus). CANADIAN JOURNAL OF ANIMAL SCIENCE 2016. [DOI: 10.1139/cjas-2015-0076] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The aim of the study was to determine the number and shape of nucleoli during meiosis in cells of the domestic horse. In addition, the level of global DNA methylation was determined using a quantitative technique for measuring the relative level of DNA methylation, modelled on an immunoenzymatic assay. The research was carried out on stallions belonging to two age groups (2 and 7 yr). In the cells of the 2-yr-old animals, the nucleoli were mainly of a regular shape and no fragmented nucleoli were observed. The cells of the 7-yr-old horses had a small percentage of regularly shaped nucleoli, and nucleoli with a fragmented structure were present. The study provides a basis for further research on epigenetic mechanisms in horses.
Collapse
Affiliation(s)
- Katarzyna Andraszek
- Department of Animal Genetics and Horse Breeding, Institute of Bioengineering and Animal Breeding, Siedlce University of Natural Sciences and Humanities, Prusa 14, Poland
| | - Magdalena Gryzińska
- Department of Biological Basis of Animal Production, University of Life Sciences, Lublin, Poland, Akademicka 13 St, 20-950 Lublin, Poland
| | - Agata Danielewicz
- Department of Animal Genetics and Horse Breeding, Institute of Bioengineering and Animal Breeding, Siedlce University of Natural Sciences and Humanities, Prusa 14, Poland
| | - Justyna Batkowska
- Department of Biological Basis of Animal Production, University of Life Sciences, Lublin, Poland, Akademicka 13 St, 20-950 Lublin, Poland
| | - Elżbieta Smalec
- Department of Animal Genetics and Horse Breeding, Institute of Bioengineering and Animal Breeding, Siedlce University of Natural Sciences and Humanities, Prusa 14, Poland
| |
Collapse
|
2
|
Baibakov B, Murtazina R, Elowsky C, Giardiello FM, Kovbasnjuk O. Shiga toxin is transported into the nucleoli of intestinal epithelial cells via a carrier-dependent process. Toxins (Basel) 2010; 2:1318-35. [PMID: 22069640 PMCID: PMC3153243 DOI: 10.3390/toxins2061318] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2010] [Revised: 05/19/2010] [Accepted: 06/03/2010] [Indexed: 12/13/2022] Open
Abstract
Shiga toxin (Stx) produced by the invasive Shigella dysenteriae serotype 1 (S. dysenteriae1) causes gastrointestinal and kidney complications. It has been assumed that Stx is released intracellularly after enterocyte invasion by S. dysenteriae1. However, there is little information about Stx distribution inside S. dysenteriae1-infected enterocytes. Here, we use intestinal epithelial T84 cells to characterize the trafficking of Stx delivered into the cytosol, in ways that mimic aspects of S. dysenteriae1 infection. We find that cytoplasmic Stx is transported into nucleoli. Stx nucleolar movement is carrier- and energy-dependent. Stx binding to the nucleoli of normal human enterocytes in vitro supports possible roles for nucleolar trafficking in toxin-induced intestinal pathology.
Collapse
Affiliation(s)
- Boris Baibakov
- GI Division, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
| | | | | | | | | |
Collapse
|
3
|
Kitsios G, Alexiou KG, Bush M, Shaw P, Doonan JH. A cyclin-dependent protein kinase, CDKC2, colocalizes with and modulates the distribution of spliceosomal components in Arabidopsis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2008; 54:220-35. [PMID: 18208522 DOI: 10.1111/j.1365-313x.2008.03414.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Cyclin-dependent kinases (CDKs) play key regulatory roles in diverse cellular functions, including cell-cycle progression, transcription and translation. In plants, CDKs have been classified into several groups, named A through to G, but the functions of most are poorly characterized. CDKCs are known to phosphorylate the C-terminal domain (CTD) of RNA polymerase II (RNAP II), and therefore the CDKC-cyclinT (CycT) complex may have a role similar to the animal CDK9-CycT complex of the positive transcription elongation factor b (P-TEFb). However, we found that the predicted structure of the Arabidopsis CDKC2 protein is more similar to the mammalian cdc2-related kinase, CRK7, than to CDK9. CRK7 is proposed to link transcription with splicing, and CDKC2 contains all the structural features of CRK7 that make the latter distinct from CDK9. Consistent with this, we show that GFP-CDKC2 fusion proteins co-localize with spliceosomal components, that the expression of CDKC2 modifies the location of these components, and that co-localization was dependent on the transcriptional status of the cells and on CDKC2-kinase activity. We propose, therefore, that the Arabidopsis CDKC2 combines the functions of both CRK7 and CDK9, and could also couple splicing with transcription.
Collapse
|
4
|
Xie SQ, Martin S, Guillot PV, Bentley DL, Pombo A. Splicing speckles are not reservoirs of RNA polymerase II, but contain an inactive form, phosphorylated on serine2 residues of the C-terminal domain. Mol Biol Cell 2006; 17:1723-33. [PMID: 16467386 PMCID: PMC1415300 DOI: 10.1091/mbc.e05-08-0726] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2005] [Revised: 01/26/2006] [Accepted: 01/30/2006] [Indexed: 11/11/2022] Open
Abstract
"Splicing speckles" are major nuclear domains rich in components of the splicing machinery and polyA(+) RNA. Although speckles contain little detectable transcriptional activity, they are found preferentially associated with specific mRNA-coding genes and gene-rich R bands, and they accumulate some unspliced pre-mRNAs. RNA polymerase II transcribes mRNAs and is required for splicing, with some reports suggesting that the inactive complexes are stored in splicing speckles. Using ultrathin cryosections to improve optical resolution and preserve nuclear structure, we find that all forms of polymerase II are present, but not enriched, within speckles. Inhibition of polymerase activity shows that speckles do not act as major storage sites for inactive polymerase II complexes but that they contain a stable pool of polymerase II phosphorylated on serine(2) residues of the C-terminal domain, which is transcriptionally inactive and may have roles in spliceosome assembly or posttranscriptional splicing of pre-mRNAs. Paraspeckle domains lie adjacent to speckles, but little is known about their protein content or putative roles in the expression of the speckle-associated genes. We find that paraspeckles are transcriptionally inactive but contain polymerase II, which remains stably associated upon transcriptional inhibition, when paraspeckles reorganize around nucleoli in the form of caps.
Collapse
Affiliation(s)
- Sheila Q Xie
- Medical Research Council Clinical Sciences Centre, Faculty of Medicine, Imperial College London, Hammersmith Hospital Campus, London W12 0NN, United Kingdom
| | | | | | | | | |
Collapse
|
5
|
Yu B, Mitchell GA, Richter A. Nucleolar localization of cirhin, the protein mutated in North American Indian childhood cirrhosis. Exp Cell Res 2005; 311:218-28. [PMID: 16225863 DOI: 10.1016/j.yexcr.2005.08.012] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2005] [Revised: 08/22/2005] [Accepted: 08/23/2005] [Indexed: 10/25/2022]
Abstract
Cirhin (NP_116219), the product of the CIRH1A gene is mutated in North American Indian childhood cirrhosis (NAIC/CIRH1A, OMIM 604901), a severe autosomal recessive intrahepatic cholestasis. It is a 686-amino-acid WD40-repeat containing protein of unknown function that is predicted to contain multiple targeting signals, including an N-terminal mitochondrial targeting signal, a C-terminal monopartite nuclear localization signal (NLS) and a bipartite nuclear localization signal (BNLS). We performed the direct determination of subcellular localization of cirhin as a crucial first step in unraveling its biological function. Using EGFP and His-tagged cirhin fusion proteins expressed in HeLa and HepG2, cells we show that cirhin is a nucleolar protein and that the R565W mutation, for which all NAIC patients are homozygous, has no effect on subcellular localization. Cirhin has an active C-terminal monopartite nuclear localization signal (NLS) and a unique nucleolar localization signal (NrLS) between residues 315 and 432. The nucleolus is not known to be important specifically for intrahepatic cholestasis. These observations provide a new dimension in the study of hereditary cholestasis.
Collapse
Affiliation(s)
- Bin Yu
- Service de Génétique médicale, Centre de recherche, Hôpital Sainte-Justine, Université de Montréal, 3175 Côte Sainte-Catherine, Québec, Canada H3T1C5
| | | | | |
Collapse
|
6
|
Shav-Tal Y, Blechman J, Darzacq X, Montagna C, Dye BT, Patton JG, Singer RH, Zipori D. Dynamic sorting of nuclear components into distinct nucleolar caps during transcriptional inhibition. Mol Biol Cell 2005; 16:2395-413. [PMID: 15758027 PMCID: PMC1087244 DOI: 10.1091/mbc.e04-11-0992] [Citation(s) in RCA: 269] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Nucleolar segregation is observed under some physiological conditions of transcriptional arrest. This process can be mimicked by transcriptional arrest after actinomycin D treatment leading to the segregation of nucleolar components and the formation of unique structures termed nucleolar caps surrounding a central body. These nucleolar caps have been proposed to arise from the segregation of nucleolar components. We show that contrary to prevailing notion, a group of nucleoplasmic proteins, mostly RNA binding proteins, relocalized from the nucleoplasm to a specific nucleolar cap during transcriptional inhibition. For instance, an exclusively nucleoplasmic protein, the splicing factor PSF, localized to nucleolar caps under these conditions. This structure also contained pre-rRNA transcripts, but other caps contained either nucleolar proteins, PML, or Cajal body proteins and in addition nucleolar or Cajal body RNAs. In contrast to the capping of the nucleoplasmic components, nucleolar granular component proteins dispersed into the nucleoplasm, although at least two (p14/ARF and MRP RNA) were retained in the central body. The nucleolar caps are dynamic structures as determined using photobleaching and require energy for their formation. These findings demonstrate that the process of nucleolar segregation and capping involves energy-dependent repositioning of nuclear proteins and RNAs and emphasize the dynamic characteristics of nuclear domain formation in response to cellular stress.
Collapse
Affiliation(s)
- Yaron Shav-Tal
- Department of Molecular Cell Biology, The Weizmann Institute of Science, Rehovot, 76100 Israel.
| | | | | | | | | | | | | | | |
Collapse
|
7
|
Senapin S, Clark-Walker GD, Chen XJ, Séraphin B, Daugeron MC. RRP20, a component of the 90S preribosome, is required for pre-18S rRNA processing in Saccharomyces cerevisiae. Nucleic Acids Res 2003; 31:2524-33. [PMID: 12736301 PMCID: PMC156047 DOI: 10.1093/nar/gkg366] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
A strain of Saccharomyces cerevisiae, defective in small subunit ribosomal RNA processing, has a mutation in YOR145c ORF that converts Gly235 to Asp. Yor145c is a nucleolar protein required for cell viability and has been reported recently to be present in 90S pre-ribosomal particles. The Gly235Asp mutation in YOR145c is found in a KH-type RNA-binding domain and causes a marked deficiency in 18S rRNA production. Detailed studies by northern blotting and primer extension analyses show that the mutant strain impairs the early pre-rRNA processing cleavage essentially at sites A1 and A2, leading to accumulation of a 22S dead-end processing product that is found in only a few rRNA processing mutants. Furthermore, U3, U14, snR10 and snR30 snoRNAs, involved in early pre-rRNA cleavages, are not destabilized by the YOR145c mutation. As the protein encoded by YOR145c is found in pre-ribosomal particles and the mutant strain is defective in ribosomal RNA processing, we have renamed it as RRP20.
Collapse
MESH Headings
- Amino Acid Sequence
- Animals
- Conserved Sequence/genetics
- DNA, Fungal/chemistry
- DNA, Fungal/genetics
- Genetic Complementation Test
- Humans
- Molecular Sequence Data
- Mutation
- Nuclear Proteins/metabolism
- RNA Precursors/genetics
- RNA Precursors/metabolism
- RNA Processing, Post-Transcriptional
- RNA, Ribosomal/genetics
- RNA, Ribosomal/metabolism
- RNA, Ribosomal, 18S/genetics
- RNA, Ribosomal, 18S/metabolism
- RNA-Binding Proteins/genetics
- RNA-Binding Proteins/metabolism
- Ribosomal Proteins/genetics
- Ribosomal Proteins/metabolism
- Ribosomes/metabolism
- Saccharomyces cerevisiae/genetics
- Saccharomyces cerevisiae/growth & development
- Saccharomyces cerevisiae/metabolism
- Saccharomyces cerevisiae Proteins/metabolism
- Sequence Alignment
- Sequence Analysis, DNA
- Sequence Homology, Amino Acid
Collapse
Affiliation(s)
- Saengchan Senapin
- Molecular Genetics and Evolution Group, Research School of Biological Sciences, The Australian National University, GPO Box 475, Canberra ACT 2601, Australia
| | | | | | | | | |
Collapse
|
8
|
Fuchsová B, Hozák P. The Localization of Nuclear DNA Helicase II in Different Nuclear Compartments Is Linked to Transcription. Exp Cell Res 2002; 279:260-70. [PMID: 12243751 DOI: 10.1006/excr.2002.5617] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Nuclear DNA helicase II (NDH II) is a member of the DEAH superfamily of helicases and functions as a pre-mRNA- and mRNA-binding protein in human cells. Here we report for the first time that human NDH II is associated with the nucleolus of transformed and nontransformed cells as shown by immunofluorescence and by ultrastructural studies. When RNA polymerase II (POL II) transcription is inhibited, NDH II highly accumulates in the nucleolus and shows predominant association with subdomains in DFC and in a portion of GC attached to DFC. Furthermore, these subdomains completely co-localize with mRNA-binding protein TLS. In addition, we show that nucleolar accumulation of NDH II is closely related to G(0)-phase growth arrest in human fibroblasts. Thus, the nucleolar localization of NDH II depends upon the metabolic state of the cell. Based on the data we propose that NDH II operates in both nucleoplasmic and nucleolar mode, and that its redistribution reflects accumulations indicating a possible cycling of NDH II between nucleoplasm and the nucleolus. The nucleolus can serve as a temporary storage or recycling center for NDH II. Possible functions of NDH II in pre-rRNA biogenesis, or in nucleolar mRNA metabolism, are also discussed.
Collapse
Affiliation(s)
- B Fuchsová
- Department of Cell Ultrastructure and Molecular Biology, Institute of Experimental Medicine, Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | | |
Collapse
|