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Kolesnikova TD, Klenov MS, Nokhova AR, Lavrov SA, Pokholkova GV, Schubert V, Maltseva SV, Cook KR, Dixon MJ, Zhimulev IF. A Spontaneous Inversion of the X Chromosome Heterochromatin Provides a Tool for Studying the Structure and Activity of the Nucleolus in Drosophila melanogaster. Cells 2022; 11:cells11233872. [PMID: 36497131 PMCID: PMC9736023 DOI: 10.3390/cells11233872] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Revised: 11/24/2022] [Accepted: 11/28/2022] [Indexed: 12/02/2022] Open
Abstract
The pericentromeric heterochromatin is largely composed of repetitive sequences, making it difficult to analyze with standard molecular biological methods. At the same time, it carries many functional elements with poorly understood mechanisms of action. The search for new experimental models for the analysis of heterochromatin is an urgent task. In this work, we used the Rif1 mutation, which suppresses the underreplication of all types of repeated sequences, to analyze heterochromatin regions in polytene chromosomes of Drosophila melanogaster. In the Rif1 background, we discovered and described in detail a new inversion, In(1)19EHet, which arose on a chromosome already carrying the In(1)sc8 inversion and transferred a large part of X chromosome heterochromatin, including the nucleolar organizer to a new euchromatic environment. Using nanopore sequencing and FISH, we have identified the eu- and heterochromatin breakpoints of In(1)19EHet. The combination of the new inversion and the Rif1 mutation provides a promising tool for studies of X chromosome heterochromatin structure, nucleolar organization, and the nucleolar dominance phenomenon. In particular, we found that, with the complete polytenization of rDNA repeats, the nucleolus consists of a cloud-like structure corresponding to the classical nucleolus of polytene chromosomes, as well as an unusual intrachromosomal structure containing alternating transcriptionally active and inactive regions.
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Affiliation(s)
- Tatyana D. Kolesnikova
- Institute of Molecular and Cellular Biology SB RAS, 630090 Novosibirsk, Russia
- Faculty of Natural Sciences, Novosibirsk State University, 630090 Novosibirsk, Russia
- Correspondence:
| | - Mikhail S. Klenov
- Department of Molecular Genetics of the Cell, Institute of Molecular Genetics of National Research Centre “Kurchatov Institute”, 123182 Moscow, Russia
| | - Alina R. Nokhova
- Faculty of Natural Sciences, Novosibirsk State University, 630090 Novosibirsk, Russia
| | - Sergey A. Lavrov
- Department of Molecular Genetics of the Cell, Institute of Molecular Genetics of National Research Centre “Kurchatov Institute”, 123182 Moscow, Russia
| | | | - Veit Schubert
- Leibniz Institute of Plant Genetics and Crop Plant Research Gatersleben, 06466 Seeland, Germany
| | - Svetlana V. Maltseva
- Faculty of Natural Sciences, Novosibirsk State University, 630090 Novosibirsk, Russia
| | - Kevin R. Cook
- Bloomington Drosophila Stock Center, Department of Biology, Indiana University, Bloomington, IN 47405, USA
| | - Michael J. Dixon
- Bloomington Drosophila Stock Center, Department of Biology, Indiana University, Bloomington, IN 47405, USA
| | - Igor F. Zhimulev
- Institute of Molecular and Cellular Biology SB RAS, 630090 Novosibirsk, Russia
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2
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Fu Y, Liu Y, Wen T, Fang J, Chen Y, Zhou Z, Gu X, Wu H, Sheng J, Xu Z, Zou W, Chen B. Real-time imaging of RNA polymerase I activity in living human cells. J Biophys Biochem Cytol 2022; 222:213608. [PMID: 36282216 PMCID: PMC9606689 DOI: 10.1083/jcb.202202110] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2022] [Revised: 08/19/2022] [Accepted: 09/27/2022] [Indexed: 11/22/2022] Open
Abstract
RNA polymerase I (Pol I) synthesizes about 60% of cellular RNA by transcribing multiple copies of the ribosomal RNA gene (rDNA). The transcriptional activity of Pol I controls the level of ribosome biogenesis and cell growth. However, there is currently a lack of methods for monitoring Pol I activity in real time. Here, we develop LiveArt (live imaging-based analysis of rDNA transcription) to visualize and quantify the spatiotemporal dynamics of endogenous ribosomal RNA (rRNA) synthesis. LiveArt reveals mitotic silencing and reactivation of rDNA transcription, as well as the transcriptional kinetics of interphase rDNA. Using LiveArt, we identify SRFBP1 as a potential regulator of rRNA synthesis. We show that rDNA transcription occurs in bursts and can be altered by modulating burst duration and amplitude. Importantly, LiveArt is highly effective in the screening application for anticancer drugs targeting Pol I transcription. These approaches pave the way for a deeper understanding of the mechanisms underlying nucleolar functions.
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Affiliation(s)
- Yujuan Fu
- Department of Cell Biology and Bone Marrow Transplantation Center of the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China,Liangzhu Laboratory, Zhejiang University Medical Center, Hangzhou, China
| | - Yaxin Liu
- Institute of Environmental Medicine, and Department of General Surgery, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Tanye Wen
- Department of Cell Biology and Bone Marrow Transplantation Center of the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Jie Fang
- Department of Cell Biology and Bone Marrow Transplantation Center of the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China,Liangzhu Laboratory, Zhejiang University Medical Center, Hangzhou, China
| | - Yalong Chen
- Department of Cell Biology and Bone Marrow Transplantation Center of the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Ziying Zhou
- Department of Cell Biology and Bone Marrow Transplantation Center of the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Xinyi Gu
- Department of Cell Biology and Bone Marrow Transplantation Center of the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Hao Wu
- Department of Cell Biology and Bone Marrow Transplantation Center of the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Jinghao Sheng
- Institute of Environmental Medicine, and Department of General Surgery, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Zhengping Xu
- Liangzhu Laboratory, Zhejiang University Medical Center, Hangzhou, China,Institute of Environmental Medicine, and Department of General Surgery, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Wei Zou
- The Fourth Affiliated Hospital, Zhejiang University School of Medicine, Yiwu, China,Insititute of Translational Medicine, Zhejiang University, Hangzhou, China,Wei Zou:
| | - Baohui Chen
- Department of Cell Biology and Bone Marrow Transplantation Center of the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China,Liangzhu Laboratory, Zhejiang University Medical Center, Hangzhou, China,Institute of Hematology, Zhejiang University and Zhejiang Engineering Laboratory for Stem Cell and Immunotherapy, Hangzhou, China,Zhejiang Provincial Key Laboratory of Genetic & Developmental Disorders, Hangzhou, China,Correspondence to Baohui Chen:
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Fefelova EA, Pleshakova IM, Mikhaleva EA, Pirogov SA, Poltorachenko V, Abramov Y, Romashin D, Shatskikh A, Blokh R, Gvozdev V, Klenov M. Impaired function of rDNA transcription initiation machinery leads to derepression of ribosomal genes with insertions of R2 retrotransposon. Nucleic Acids Res 2022; 50:867-884. [PMID: 35037046 PMCID: PMC8789037 DOI: 10.1093/nar/gkab1276] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2021] [Revised: 11/21/2021] [Accepted: 12/14/2021] [Indexed: 12/14/2022] Open
Abstract
Eukaryotic genomes harbor hundreds of rRNA genes, many of which are transcriptionally silent. However, little is known about selective regulation of individual rDNA units. In Drosophila melanogaster, some rDNA repeats contain insertions of the R2 retrotransposon, which is capable to be transcribed only as part of pre-rRNA molecules. rDNA units with R2 insertions are usually inactivated, although R2 expression may be beneficial in cells with decreased rDNA copy number. Here we found that R2-inserted rDNA units are enriched with HP1a and H3K9me3 repressive mark, whereas disruption of the heterochromatin components slightly affects their silencing in ovarian germ cells. Surprisingly, we observed a dramatic upregulation of R2-inserted rRNA genes in ovaries lacking Udd (Under-developed) or other subunits (TAF1b and TAF1c-like) of the SL1-like complex, which is homologues to mammalian Selective factor 1 (SL1) involved in rDNA transcription initiation. Derepression of rRNA genes with R2 insertions was accompanied by a reduction of H3K9me3 and HP1a enrichment. We suggest that the impairment of the SL1-like complex affects a mechanism of selective activation of intact rDNA units which competes with heterochromatin formation. We also propose that R2 derepression may serve as an adaptive response to compromised rRNA synthesis.
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Affiliation(s)
- Elena A Fefelova
- Department of Molecular Genetics of the Cell, Institute of Molecular Genetics of National Research Centre «Kurchatov Institute», Moscow 123182, Russia
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena 91125, USA
| | - Irina M Pleshakova
- Department of Molecular Genetics of the Cell, Institute of Molecular Genetics of National Research Centre «Kurchatov Institute», Moscow 123182, Russia
- Laboratory for Neurobiology of Memory, P.K. Anokhin Institute of Normal Physiology, Moscow 125315, Russia
| | - Elena A Mikhaleva
- Department of Molecular Genetics of the Cell, Institute of Molecular Genetics of National Research Centre «Kurchatov Institute», Moscow 123182, Russia
| | - Sergei A Pirogov
- Department of Molecular Genetics of the Cell, Institute of Molecular Genetics of National Research Centre «Kurchatov Institute», Moscow 123182, Russia
| | - Valentin A Poltorachenko
- Department of Molecular Genetics of the Cell, Institute of Molecular Genetics of National Research Centre «Kurchatov Institute», Moscow 123182, Russia
| | - Yuri A Abramov
- Department of Molecular Genetics of the Cell, Institute of Molecular Genetics of National Research Centre «Kurchatov Institute», Moscow 123182, Russia
| | - Daniil D Romashin
- Laboratory of Precision Biosystems, V. N. Orekhovich Institute of Biomedical Chemistry, 10 Pogodinskaya St., Moscow 119121, Russia
| | - Aleksei S Shatskikh
- Department of Molecular Genetics of the Cell, Institute of Molecular Genetics of National Research Centre «Kurchatov Institute», Moscow 123182, Russia
| | - Roman S Blokh
- Department of Molecular Genetics of the Cell, Institute of Molecular Genetics of National Research Centre «Kurchatov Institute», Moscow 123182, Russia
- Department of Functional Genomics, Institute of Gene Biology, Russian Academy of Sciences, 34/5 Vavilova Street, Moscow 119334, Russia
| | - Vladimir A Gvozdev
- Department of Molecular Genetics of the Cell, Institute of Molecular Genetics of National Research Centre «Kurchatov Institute», Moscow 123182, Russia
| | - Mikhail S Klenov
- Department of Molecular Genetics of the Cell, Institute of Molecular Genetics of National Research Centre «Kurchatov Institute», Moscow 123182, Russia
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Guerrero PA, Maggert KA. The CCCTC-binding factor (CTCF) of Drosophila contributes to the regulation of the ribosomal DNA and nucleolar stability. PLoS One 2011; 6:e16401. [PMID: 21283722 PMCID: PMC3024428 DOI: 10.1371/journal.pone.0016401] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2010] [Accepted: 12/15/2010] [Indexed: 01/14/2023] Open
Abstract
In the repeat array of ribosomal DNA (rDNA), only about half of the genes are actively transcribed while the others are silenced. In arthropods, transposable elements interrupt a subset of genes, often inactivating transcription of those genes. Little is known about the establishment or separation of juxtaposed active and inactive chromatin domains, or preferential inactivation of transposable element interrupted genes, despite identity in promoter sequences. CTCF is a sequence-specific DNA binding protein which is thought to act as a transcriptional repressor, block enhancer-promoter communication, and delimit juxtaposed domains of active and inactive chromatin; one or more of these activities might contribute to the regulation of this repeated gene cluster. In support of this hypothesis, we show that the Drosophila nucleolus contains CTCF, which is bound to transposable element sequences within the rDNA. Reduction in CTCF gene activity results in nucleolar fragmentation and reduced rDNA silencing, as does disruption of poly-ADP-ribosylation thought to be necessary for CTCF nucleolar localization. Our data establish a role for CTCF as a component necessary for proper control of transposable element-laden rDNA transcription and nucleolar stability.
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Affiliation(s)
- Paola A. Guerrero
- Department of Biochemistry/Biophysics, Texas A&M University, College Station, Texas, United States of America
| | - Keith A. Maggert
- Department of Biology, Texas A&M University, College Station, Texas, United States of America
- * E-mail:
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Suter M, Bocock P, Showalter L, Hu M, Shope C, McKnight R, Grove K, Lane R, Aagaard-Tillery K. Epigenomics: maternal high-fat diet exposure in utero disrupts peripheral circadian gene expression in nonhuman primates. FASEB J 2010; 25:714-26. [PMID: 21097519 DOI: 10.1096/fj.10-172080] [Citation(s) in RCA: 110] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The effect of in utero exposure to a maternal high-fat diet on the peripheral circadian system of the fetus is unknown. Using mRNA copy number analysis, we report that the components of the peripheral circadian machinery are transcribed in the nonhuman primate fetal liver in an intact phase-antiphase fashion and that Npas2, a paralog of the Clock transcription factor, serves as the rate-limiting transcript by virtue of its relative low abundance (10- to 1000-fold lower). We show that exposure to a maternal high-fat diet in utero significantly alters the expression of fetal hepatic Npas2 (up to 7.1-fold, P<0.001) compared with that in control diet-exposed animals and is reversible in fetal offspring from obese dams reversed to a control diet (1.3-fold, P>0.05). Although the Npas2 promoter remains largely unmethylated, differential Npas2 promoter occupancy of acetylation of fetal histone H3 at lysine 14 (H3K14ac) occurs in response to maternal high-fat diet exposure compared with control diet-exposed animals. Furthermore, we find that disruption of Npas2 is consistent with high-fat diet exposure in juvenile animals, regardless of in utero diet exposure. In summary, the data suggest that peripheral Npas2 expression is uniquely vulnerable to diet exposure.
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Affiliation(s)
- Melissa Suter
- Department of Obstetrics and Gynecology, Baylor College of Medicine, Houston, Texas, USA
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Abstract
The 35S ribosomal RNA genes (rDNA) are organized as repeated arrays in many organisms. Epigenetic regulation of transcription of the rRNA results in only a subset of copies being transcribed, making rDNA an important model for understanding epigenetic chromatin modification. We have created an allelic series of deletions within the rDNA array of the Drosophila Y chromosome that affect nucleolus size and morphology, but do not limit steady-state rRNA concentrations. These rDNA deletions result in reduced heterochromatin-induced gene silencing elsewhere in the genome, and the extent of the rDNA deletion correlates with the loss of silencing. Consistent with this, chromosomes isolated from strains mutated in genes required for proper heterochromatin formation have very small rDNA arrays, reinforcing the connection between heterochromatin and the rDNA. In wild-type cells, which undergo spontaneous natural rDNA loss, we observed the same correlation between loss of rDNA and loss of heterochromatin-induced silencing, showing that the volatility of rDNA arrays may epigenetically influence gene expression through normal development and differentiation. We propose that the rDNA contributes to a balance between heterochromatin and euchromatin in the nucleus, and alterations in rDNA--induced or natural--affect this balance.
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