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Salinas-Pena M, Rebollo E, Jordan A. Imaging analysis of six human histone H1 variants reveals universal enrichment of H1.2, H1.3, and H1.5 at the nuclear periphery and nucleolar H1X presence. eLife 2024; 12:RP91306. [PMID: 38530350 DOI: 10.7554/elife.91306] [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] [Indexed: 03/27/2024] Open
Abstract
Histone H1 participates in chromatin condensation and regulates nuclear processes. Human somatic cells may contain up to seven histone H1 variants, although their functional heterogeneity is not fully understood. Here, we have profiled the differential nuclear distribution of the somatic H1 repertoire in human cells through imaging techniques including super-resolution microscopy. H1 variants exhibit characteristic distribution patterns in both interphase and mitosis. H1.2, H1.3, and H1.5 are universally enriched at the nuclear periphery in all cell lines analyzed and co-localize with compacted DNA. H1.0 shows a less pronounced peripheral localization, with apparent variability among different cell lines. On the other hand, H1.4 and H1X are distributed throughout the nucleus, being H1X universally enriched in high-GC regions and abundant in the nucleoli. Interestingly, H1.4 and H1.0 show a more peripheral distribution in cell lines lacking H1.3 and H1.5. The differential distribution patterns of H1 suggest specific functionalities in organizing lamina-associated domains or nucleolar activity, which is further supported by a distinct response of H1X or phosphorylated H1.4 to the inhibition of ribosomal DNA transcription. Moreover, H1 variants depletion affects chromatin structure in a variant-specific manner. Concretely, H1.2 knock-down, either alone or combined, triggers a global chromatin decompaction. Overall, imaging has allowed us to distinguish H1 variants distribution beyond the segregation in two groups denoted by previous ChIP-Seq determinations. Our results support H1 variants heterogeneity and suggest that variant-specific functionality can be shared between different cell types.
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Affiliation(s)
| | - Elena Rebollo
- Molecular Biology Institute of Barcelona (IBMB-CSIC), Barcelona, Spain
| | - Albert Jordan
- Molecular Biology Institute of Barcelona (IBMB-CSIC), Barcelona, Spain
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Wang J, Huang J, Ding H, Ma J, Zhong H, Wang F, Chen Y, Peng H. Functional analysis of tumor-derived immunoglobulin lambda and its interacting proteins in cervical cancer. BMC Cancer 2023; 23:929. [PMID: 37784026 PMCID: PMC10544594 DOI: 10.1186/s12885-023-11426-9] [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: 03/25/2023] [Accepted: 09/21/2023] [Indexed: 10/04/2023] Open
Abstract
BACKGROUND Immunoglobulin lambda (Igλ) has been reported to be expressed in many normal and tumor tissues and cells. However, the function and clinical significance of tumor-derived Igλ remain unclear. METHODS The differential expressions of Immunoglobulin Lambda Constants (IGLCs) in cervical squamous cell carcinoma and endocervical adenocarcinoma (CESC) were examined with The Cancer Genome Atlas (TCGA), Genotype-Tissue Expression (GTEx), and Human Protein Atlas (HPA) databases. The effects of IGLCs on patient clinical phenotypes and prognosis were explored via bioinformatics analyses based on the TCGA databases. We used the bioinformatics analyses based on the TCGA and GTEx databases to elucidate the correlations among IGLC expressions, immunomodulator expressions, tumor stemness, and infiltration scores of tumor infiltrating immune cells. Co-immunoprecipitation (Co-IP) and silver staining combined with liquid chromatography-tandem mass spectrometry (LC-MS/MS) were used to obtain potential tumor-derived Igλ-interacting proteins. Functional annotation of candidate proteins identified by LC-MS/MS was performed in Database for Annotation, Visualization and Integrated Discovery (DAVID). The bioinformatics analyses of 7 IGLCs in CESC and normal cervical tissues were performed based on TCGA, GTEx, and Gene Expression Profiling Interactive Analysis 2 (GEPIA2) databases. Protein-protein interaction (PPI) network was analyzed based on tumor-derived Igλ-interacting proteins in Search Tool for the Retrieval of Interacting Genes/Proteins (STRING) database. Immunohistochemistry (IHC) was used to validate the expressions of IGLCs in CESC. RESULTS We found that the expressions of the majority of IGLCs (IGLC1, IGLC2, IGLC3, IGLC4, IGLC5, IGLC6, and IGLC7) were upregulated in CESC tissues, compared with those in normal cervical tissues. The expressions of IGLC5 and IGLC7 had significant difference in different pathologic metastasis (M), one of tumor, node, and metastasis (TNM) staging system, categories of CESC. Except for disease-free interval (DFI), 4 IGLC (IGLC1, IGLC2, IGLC3, and IGLC7) expression levels were positively associated with patient overall survival (OS), disease-specific survival (DSS), and progression-free interval (PFI) respectively in CESC tissues. 5 IGLC (IGLC1, IGLC2, IGLC3, IGLC6, and IGLC7) expressions were positively correlated with the expressions of a majority of immunomodulators respectively in CESC tissues. Tumor stemness was negatively correlated with the expressions of 4 IGLCs (IGLC1, IGLC2, IGLC3, and IGLC7) respectively in CESC tissues. Except for IGLC4, IGLC5, and IGLC7, 4 IGLC (IGLC1, IGLC2, IGLC3, and IGLC6) expressions were positively correlated with infiltration scores of 6 tumor-infiltrating immune cells (B cell, T cell CD4, T cell CD8, neutrophil, macrophage, and DC). After analyses of the above bioinformatics data of tumor-derived Igλ, Co-IP and LC-MS/MS were used to confirm that 4 proteins (RPL7, RPS3, H1-5, and H1-6) might interact with tumor-derived Igλ in cervical cancer cells. Functional analyses of these candidate proteins showed that they interacted with many proteins and were involved in various cellular biological processes. Finally, IHC was used to further confirm the above bioinformatics results, it was indicated that the expression level of Igλ in cervical adenocarcinoma and cervical squamous cell carcinoma was higher than that in normal cervical tissue. CONCLUSION This study comprehensively investigated the functions of tumor-derived Igλ and its interacting proteins based on bioinformatics analysis and the potential value of Igλ as a prognostic and therapeutic marker for CESC, providing new direction and evidence for CESC therapy.
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Affiliation(s)
- Juping Wang
- Department of Pathology, The First Affiliated Hospital of Fujian Medical University, Fuzhou, China.
- Department of Pathology, Binhai Branch of National Regional Medical Center, The First Affiliated Hospital, Fujian Medical University, Fuzhou, China.
| | - Jiangni Huang
- Department of Pathophysiology, School of Basic Medical Sciences, Youjiang Medical University for Nationalities, Baise, China
| | - Hao Ding
- Department of Pathophysiology, School of Basic Medical Sciences, Youjiang Medical University for Nationalities, Baise, China
| | - Jing Ma
- Department of Pathophysiology, School of Basic Medical Sciences, Youjiang Medical University for Nationalities, Baise, China
| | - Haohua Zhong
- Department of Pathophysiology, School of Basic Medical Sciences, Youjiang Medical University for Nationalities, Baise, China
| | - Fanlu Wang
- Department of Pathophysiology, School of Basic Medical Sciences, Youjiang Medical University for Nationalities, Baise, China
| | - Yupeng Chen
- Department of Pathology, The First Affiliated Hospital of Fujian Medical University, Fuzhou, China
| | - Hui Peng
- Fujian Provincial Institutes of Brain Disorders and Brain Sciences, The First Affiliated Hospital, Fujian Medical University, Fuzhou, China.
- Department of Neurosurgery, The First Affiliated Hospital, Neurosurgery Research Institute, Fujian Medical University, Fuzhou, China.
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Sou IF, Hamer G, Tee WW, Vader G, McClurg UL. Cancer and meiotic gene expression: Two sides of the same coin? Curr Top Dev Biol 2022; 151:43-68. [PMID: 36681477 DOI: 10.1016/bs.ctdb.2022.06.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Meiosis increases genetic diversity in offspring by generating genetically unique haploid gametes with reshuffled chromosomes. This process requires a specialized set of meiotic proteins, which facilitate chromosome recombination and segregation. However, re-expression of meiotic proteins in mitosis can have catastrophic oncogenic consequences and aberrant expression of meiotic proteins is a common occurrence in human tumors. Mechanistically, re-activation of meiotic genes in cancer promotes oncogenesis likely because cancers-conversely to healthy mitosis-are fueled by genetic instability which promotes tumor evolution, and evasion of immune response and treatment pressure. In this review, we explore similarities between meiotic and cancer cells with a particular focus on the oncogenic activation of meiotic genes in cancer. We emphasize the role of histones and their modifications, DNA methylation, genome organization, R-loops and the availability of distal enhancers.
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Affiliation(s)
- Ieng Fong Sou
- Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool, United Kingdom; Chromatin Dynamics and Disease Epigenetics Group, Institute of Molecular and Cell Biology, Agency for Science, Technology and Research (A*STAR), Singapore, Singapore
| | - Geert Hamer
- Center for Reproductive Medicine, Reproductive Biology Laboratory, Amsterdam Reproduction and Development Research Institute, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
| | - Wee-Wei Tee
- Chromatin Dynamics and Disease Epigenetics Group, Institute of Molecular and Cell Biology, Agency for Science, Technology and Research (A*STAR), Singapore, Singapore; Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Gerben Vader
- Center for Reproductive Medicine, Reproductive Biology Laboratory, Amsterdam Reproduction and Development Research Institute, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands; Section of Oncogenetics, Department of Human Genetics, Amsterdam UMC, Vrije Universiteit, Amsterdam, The Netherlands; Cancer Center Amsterdam, Cancer Biology and Immunology, Amsterdam, The Netherlands
| | - Urszula Lucja McClurg
- Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool, United Kingdom.
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Oocyte-specific linker histone H1foo interacts with Esrrb to induce chromatin decondensation at specific gene loci. Biochem Biophys Res Commun 2021; 561:165-171. [PMID: 34023782 DOI: 10.1016/j.bbrc.2021.05.033] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Accepted: 05/11/2021] [Indexed: 11/21/2022]
Abstract
Linker histone H1 is mainly localized in the linker DNA region, between two nucleosome cores, and regulates chromatin structures linking gene expression. Mammalian oocytes contain the histone H1foo, a distinct member with low sequence similarity to other members in the H1 histone family. Although, from various previous studies, evidence related to H1foo function in chromatin structures is being accumulated, the distribution of H1foo at the target gene loci in a genome-wide manner and the molecular mechanism of H1foo-dependent chromatin architecture remain unclear. In this study, we aimed to identify the target loci and the physiological factor bound to H1foo at the loci. Chromatin immunoprecipitation sequencing analysis of H1foo-overexpressing mouse embryonic stem cells showed that H1foo is enriched around the transcriptional start sites of genes such as oocyte-specific genes and that the chromatin structures at these regions were relaxed. We demonstrated that H1foo was physiologically bound to the nuclear receptor estrogen-related receptor beta (Esrrb), and Esrrb was necessary for H1foo activity of chromatin decondensation at the target loci. The specific localization and interaction with Esrrb were validated in endogenous H1foo of oocytes. Overall, H1foo induces chromatin decondensation in a locus-specific manner and this function is achieved by interacting with Esrrb.
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Abstract
Eukaryotic nucleosomes organize chromatin by wrapping 147 bp of DNA around a histone core particle comprising two molecules each of histone H2A, H2B, H3 and H4. The DNA entering and exiting the particle may be bound by the linker histone H1. Whereas deposition of bulk histones is confined to S-phase, paralogs of the common histones, known as histone variants, are available to carry out functions throughout the cell cycle and accumulate in post-mitotic cells. Histone variants confer different structural properties on nucleosomes by wrapping more or less DNA or by altering nucleosome stability. They carry out specialized functions in DNA repair, chromosome segregation and regulation of transcription initiation, or perform tissue-specific roles. In this Cell Science at a Glance article and the accompanying poster, we briefly examine new insights into histone origins and discuss variants from each of the histone families, focusing on how structural differences may alter their functions. Summary: Histone variants change the structural properties of nucleosomes by wrapping more or less DNA, altering nucleosome stability or carrying out specialized functions.
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Affiliation(s)
- Paul B Talbert
- Howard Hughes Medical Institute, Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue N, Seattle, WA 98109, USA
| | - Steven Henikoff
- Howard Hughes Medical Institute, Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue N, Seattle, WA 98109, USA
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Kehoe S, Jewgenow K, Johnston PR, Mbedi S, Braun BC. Signalling pathways and mechanistic cues highlighted by transcriptomic analysis of primordial, primary, and secondary ovarian follicles in domestic cat. Sci Rep 2021; 11:2683. [PMID: 33514822 PMCID: PMC7846758 DOI: 10.1038/s41598-021-82051-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Accepted: 01/11/2021] [Indexed: 12/16/2022] Open
Abstract
In vitro growth (IVG) of dormant primordial ovarian follicles aims to produce mature competent oocytes for assisted reproduction. Success is dependent on optimal in vitro conditions complemented with an understanding of oocyte and ovarian follicle development in vivo. Complete IVG has not been achieved in any other mammalian species besides mice. Furthermore, ovarian folliculogenesis remains sparsely understood overall. Here, gene expression patterns were characterised by RNA-sequencing in primordial (PrF), primary (PF), and secondary (SF) ovarian follicles from Felis catus (domestic cat) ovaries. Two major transitions were investigated: PrF-PF and PF-SF. Transcriptional analysis revealed a higher proportion in gene expression changes during the PrF-PF transition. Key influencing factors during this transition included the interaction between the extracellular matrix (ECM) and matrix metalloproteinase (MMPs) along with nuclear components such as, histone HIST1H1T (H1.6). Conserved signalling factors and expression patterns previously described during mammalian ovarian folliculogenesis were observed. Species-specific features during domestic cat ovarian folliculogenesis were also found. The signalling pathway terms "PI3K-Akt", "transforming growth factor-β receptor", "ErbB", and "HIF-1" from the functional annotation analysis were studied. Some results highlighted mechanistic cues potentially involved in PrF development in the domestic cat. Overall, this study provides an insight into regulatory factors and pathways during preantral ovarian folliculogenesis in domestic cat.
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Affiliation(s)
- Shauna Kehoe
- Reproduction Biology Department, Leibniz Institute for Zoo and Wildlife Research, Alfred-Kowalke-Straße 17, 10315, Berlin, Germany.
| | - Katarina Jewgenow
- Reproduction Biology Department, Leibniz Institute for Zoo and Wildlife Research, Alfred-Kowalke-Straße 17, 10315, Berlin, Germany
| | - Paul R Johnston
- Berlin Center for Genomics in Biodiversity Research BeGenDiv, Königin-Luise-Straße 6-8, D-14195, Berlin, Germany
- Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Müggelseedamm 310, 12587, Berlin, Germany
- Freie Universität Berlin, Institut für Biologie, Königin-Luise-Straße 1-3, 14195, Berlin, Germany
| | - Susan Mbedi
- Berlin Center for Genomics in Biodiversity Research BeGenDiv, Königin-Luise-Straße 6-8, D-14195, Berlin, Germany
- Museum für Naturkunde, Invalidenstraße 43, 10115, Berlin, Germany
| | - Beate C Braun
- Reproduction Biology Department, Leibniz Institute for Zoo and Wildlife Research, Alfred-Kowalke-Straße 17, 10315, Berlin, Germany
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Hayakawa K, Tani R, Nishitani K, Tanaka S. Linker histone variant H1T functions as a chromatin de-condenser on genic regions. Biochem Biophys Res Commun 2020; 528:685-690. [PMID: 32513538 DOI: 10.1016/j.bbrc.2020.05.119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Accepted: 05/16/2020] [Indexed: 10/24/2022]
Abstract
Linker histone H1 is mainly localized in the linker DNA region, between two nucleosome cores, and regulates chromatin structures linking gene expression. There are 11 variants in histone H1, and each variant has unique functions. Our previous study demonstrates that one of the H1 variants, H1T is mainly localized in the nucleolus and targets the rDNA repeat region. Moreover, H1T condenses the chromatin structures on rDNA to repress pre-rRNA expression. Although H1T is partially localized in the nucleoplasm area, the functions of H1T in the non-repeat genic region are unclear. In this study, we aimed to identify the target loci and the role of H1T in the genic region. Chromatin immunoprecipitation sequencing analysis showed that H1T is localized around the transcriptional start site and the chromatin structures of the region were relaxed. H1T knockdown and overexpression experiments revealed that H1T induced chromatin de-condensation and was associated with the increased expression of target genes. Moreover, we observed H1T co-localization with transcriptional factor SPZ1 on the genic region. Collectively, H1T has opposing roles in the genic region and in rDNA repeats; H1T functions to facilitate chromatin relaxation linked gene activation.
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Affiliation(s)
- Koji Hayakawa
- Department of Toxicology, Faculty of Veterinary Medicine, Okayama University of Science, Imabari-shi, Ehime, Japan; Laboratory of Cellular Biochemistry, Department of Animal Resource Sciences/Veterinary Medical Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, Japan.
| | - Ruiko Tani
- Laboratory of Cellular Biochemistry, Department of Animal Resource Sciences/Veterinary Medical Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Kenta Nishitani
- Laboratory of Cellular Biochemistry, Department of Animal Resource Sciences/Veterinary Medical Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Satoshi Tanaka
- Laboratory of Cellular Biochemistry, Department of Animal Resource Sciences/Veterinary Medical Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
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Mahadevan IA, Kumar S, Rao MRS. Linker histone variant H1t is closely associated with repressed repeat-element chromatin domains in pachytene spermatocytes. Epigenetics Chromatin 2020; 13:9. [PMID: 32131873 PMCID: PMC7057672 DOI: 10.1186/s13072-020-00335-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Accepted: 02/20/2020] [Indexed: 12/22/2022] Open
Abstract
Background H1t is the major linker histone variant in pachytene spermatocytes, where it constitutes 50–60% of total H1. This linker histone variant was previously reported to localize in the nucleolar rDNA element in mouse spermatocytes. Our main aim was to determine the extra-nucleolar localization of this linker histone variant in pachytene spermatocytes. Results We generated H1t-specific antibodies in rabbits and validated its specificity by multiple assays like ELISA, western blot, etc. Genome-wide occupancy studies, as determined by ChIP-sequencing in P20 mouse testicular cells revealed that H1t did not closely associate with active gene promoters and open chromatin regions. Annotation of H1t-bound genomic regions revealed that H1t is depleted from DSB hotspots and TSS, but are predominantly associated with retrotransposable repeat elements like LINE and LTR in pachytene spermatocytes. These chromatin domains are repressed based on co-association of H1t observed with methylated CpGs and repressive histone marks like H3K9me3 and H4K20me3 in vivo. Mass spectrometric analysis of proteins associated with H1t-containing oligonucleosomes identified piRNA–PIWI pathway proteins, repeat repression-associated proteins and heterochromatin proteins confirming the association with repressed repeat-element genomic regions. We validated the interaction of key proteins with H1t-containing oligonucleosomes by use of ChIP-western blot assays. On the other hand, we observe majority of H1t peaks to be associated with the intergenic spacer of the rDNA element, also in association with SINE elements of the rDNA element. Thus, we have identified the genomic and chromatin features of both nucleolar and extranucleolar localization patterns of linker histone H1t in the context of pachytene spermatocytes. Conclusions H1t-containing repeat-element LINE and LTR chromatin domains are associated with repressive marks like methylated CpGs, histone modifications H3K9me3 and H4K20me3, and heterochromatin proteins like HP1β, Trim28, PIWIL1, etc. Apart from localization of H1t at the rDNA element, we demonstrate the extranucleolar association of this linker histone variant at repeat-associated chromatin domains in pachytene spermatocytes. We hypothesize that H1t might induce local chromatin relaxation to recruit heterochromatin and repeat repression-associated protein factors necessary for TE (transposable element) repression, the final biological effect being formation of closed chromatin repressed structures.
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Affiliation(s)
- Iyer Aditya Mahadevan
- Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore, India
| | - Sanjeev Kumar
- BioCOS Life Sciences Private Limited, SAAMI Building, 851/A, AECS Layout, B-Block, Singasandra Hosur Road, Bangalore, India
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The Integration of a Three-Dimensional Spheroid Cell Culture Operation in a Circulating Tumor Cell (CTC) Isolation and Purification Process: A Preliminary Study of the Clinical Significance and Prognostic Role of the CTCs Isolated from the Blood Samples of Head and Neck Cancer Patients. Cancers (Basel) 2019; 11:cancers11060783. [PMID: 31174311 PMCID: PMC6627984 DOI: 10.3390/cancers11060783] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2019] [Revised: 05/28/2019] [Accepted: 06/04/2019] [Indexed: 02/08/2023] Open
Abstract
Conventional positive and negative selection-based circulating tumor cell (CTC) isolation methods might generally ignore metastasis-relevant CTCs that underwent epithelial-to- mesenchymal transition and suffer from a low CTC purity problem, respectively. To address these issues, we previously proposed a 2-step CTC isolation method integrating a negative selection CTC isolation and subsequent spheroid cell culture. In addition to its ability to isolate CTCs, more importantly, the spheroid cell culture used could serve as a cell culture model mimicking the process of new tumor tissue formation during cancer metastasis. Therefore, it is promising not only to selectively isolate metastasis-relevant CTCs but also to test the potential of cancer metastasis and thus the prognosis of disease. To explore these issues, experiments were performed. The key findings of this study demonstrated that the method was able to harvest both epithelial (E)- and mesenchymal (M)-type CTCs without selection bias. Moreover, both the M-type CTC count and the information obtained from the multidrug resistance-associated protein 2 (MRP2) and MRP5 gene expression analysis of the CTCs isolated via the 2-step CTC isolation method might be able to serve as prognostic factors for progression-free survival in head and neck squamous cell carcinoma.
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Chen J, Teo BHD, Cai Y, Wee SYK, Lu J. The linker histone H1.2 is a novel component of the nucleolar organizer regions. J Biol Chem 2018; 293:2358-2369. [PMID: 29301938 DOI: 10.1074/jbc.m117.810184] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Revised: 12/18/2017] [Indexed: 01/27/2023] Open
Abstract
The nucleoli accumulate rRNA genes and are the sites of rRNA synthesis and rRNA assembly into ribosomes. During mitosis, nucleoli dissociate, but nucleolar remnants remain on the rRNA gene loci, forming distinct nucleolar organizer regions (NORs). Little is known about the composition and structure of NORs, but upstream binding factor (UBF) has been established as its master organizer. In this study, we sought to establish new proteins in NORs. Using UBF-Sepharose to isolate UBF-binding proteins, we identified histone H1.2 as a candidate partner but were puzzled by this observation, given that UBF is known to be located predominantly in nucleoli, whereas H1.2 distributed broadly among the chromatins in interphase nuclei. We then examined cells undergoing mitosis and saw that both H1.2 and UBF were recruited into NORs in this state, reconciling the results of our UBF pulldowns. Inhibiting rRNA synthesis in interphase nuclei also induced NOR-like structures containing both UBF and H1.2. When chromosomes were isolated and spread on coverslips, NORs appeared separated from the chromosomes containing both UBF and H1.2. After chromosomes were fragmented by homogenization, intact NORs remained visible. Results collectively suggest that NORs are independent structures and that the linker histone H1.2 is a novel component of this structure.
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Affiliation(s)
- Junjie Chen
- From the Department of Microbiology and Immunology, Yong Loo Lin School of Medicine and Immunology Programme, National University of Singapore, Singapore 117697
| | - Boon Heng Dennis Teo
- From the Department of Microbiology and Immunology, Yong Loo Lin School of Medicine and Immunology Programme, National University of Singapore, Singapore 117697
| | - Yitian Cai
- From the Department of Microbiology and Immunology, Yong Loo Lin School of Medicine and Immunology Programme, National University of Singapore, Singapore 117697
| | - Seng Yin Kelly Wee
- From the Department of Microbiology and Immunology, Yong Loo Lin School of Medicine and Immunology Programme, National University of Singapore, Singapore 117697
| | - Jinhua Lu
- From the Department of Microbiology and Immunology, Yong Loo Lin School of Medicine and Immunology Programme, National University of Singapore, Singapore 117697
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Kilaru S, Schuster M, Ma W, Steinberg G. Fluorescent markers of various organelles in the wheat pathogen Zymoseptoria tritici. Fungal Genet Biol 2017; 105:16-27. [PMID: 28579390 PMCID: PMC5536155 DOI: 10.1016/j.fgb.2017.05.001] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Revised: 05/05/2017] [Accepted: 05/06/2017] [Indexed: 12/22/2022]
Abstract
17 vectors are described that allow labelling of 7 subcellular structures. The fluorescent markers target the plasma membrane, endoplasmic reticulum, nucleus. Markers also target the actin cytoskeleton, peroxisomes and autophagosomes. These markers complete are toolkit of fluorescent reporters. Reporters allow cell biological studies in the Septoria tritici blotch fungus.
Development of novel strategies to control fungal plant pathogens requires understanding of their cellular organisation and biology. Live cell imaging of fluorescent organelle markers has provided valuable insight into various aspects of their cell biology, including invasion strategies in plant pathogenic fungi. Here, we introduce a set of 17 vectors that encode fluorescent markers to visualize the plasma membrane, endoplasmic reticulum (ER), chromosomes, the actin cytoskeleton, peroxisomes and autophagosomes in the wheat pathogen Zymoseptoria tritici. We fused either enhanced green-fluorescent protein (eGFP) or a codon-optimised version of GFP (ZtGFP) to homologues of a plasma membrane-located Sso1-like syntaxin, an ER signalling and retention peptide, a histone H1 homologue, the LifeAct actin-binding peptide, a mitochondrial acetyl-CoA dehydrogenase, a peroxisomal import signal and a homologue of the ubiquitin-like autophagosomal protein Atg8. We expressed these markers in wildtype strain IPO323 and confirmed the specificity of these markers by counterstaining or physiological experiments. This new set of molecular tools will help understanding the cell biology of the wheat pathogen Z. tritici.
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Affiliation(s)
- S Kilaru
- School of Biosciences, University of Exeter, Exeter EX4 4QD, UK
| | - M Schuster
- School of Biosciences, University of Exeter, Exeter EX4 4QD, UK
| | - W Ma
- School of Biosciences, University of Exeter, Exeter EX4 4QD, UK
| | - G Steinberg
- School of Biosciences, University of Exeter, Exeter EX4 4QD, UK; University of Utrecht, Department of Biology, Padualaan 8, 3584 CH Utrecht, The Netherlands.
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