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Rajkumar MS, Tembhare K, Garg R, Jain M. Genome-wide mapping of DNase I hypersensitive sites revealed differential chromatin accessibility and regulatory DNA elements under drought stress in rice cultivars. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2024. [PMID: 38859561 DOI: 10.1111/tpj.16864] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2023] [Revised: 04/08/2024] [Accepted: 05/22/2024] [Indexed: 06/12/2024]
Abstract
Drought stress (DS) is one of the major constraints limiting yield in crop plants including rice. Gene regulation under DS is largely governed by accessibility of the transcription factors (TFs) to their cognate cis-regulatory elements (CREs). In this study, we used DNase I hypersensitive assays followed by sequencing to identify the accessible chromatin regions under DS in a drought-sensitive (IR64) and a drought-tolerant (N22) rice cultivar. Our results indicated that DNase I hypersensitive sites (DHSs) were highly enriched at transcription start sites (TSSs) and numerous DHSs were detected in the promoter regions. DHSs were concurrent with epigenetic marks and the genes harboring DHSs in their TSS and promoter regions were highly expressed. In addition, DS induced changes in DHSs (∆DHSs) in TSS and promoter regions were positively correlated with upregulation of several genes involved in drought/abiotic stress response, those encoding TFs and located within drought-associated quantitative trait loci, much preferentially in the drought-tolerant cultivar. The CREs representing the binding sites of TFs involved in DS response were detected within the ∆DHSs, suggesting differential accessibility of TFs to their cognate sites under DS in different rice cultivars, which may be further deployed for enhancing drought tolerance in rice.
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Affiliation(s)
- Mohan Singh Rajkumar
- School of Computational and Integrative Sciences, Jawaharlal Nehru University, New Delhi, 110067, India
| | - Kunal Tembhare
- School of Computational and Integrative Sciences, Jawaharlal Nehru University, New Delhi, 110067, India
| | - Rohini Garg
- Department of Life Sciences, School of Natural Sciences, Shiv Nadar University, Gautam Buddha Nagar, Uttar Pradesh, 201314, India
| | - Mukesh Jain
- School of Computational and Integrative Sciences, Jawaharlal Nehru University, New Delhi, 110067, India
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2
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Buccinnà B, Ramondetti C, Piccinini M. Ampk Activation Attenuates Her3 Upregulation And Neuregulin-Mediated Rescue of Cell Proliferation in Her2-Overexpressing Breast Cancer Cell Lines Exposed to Lapatinib. Biochem Pharmacol 2022; 204:115228. [PMID: 36007575 DOI: 10.1016/j.bcp.2022.115228] [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: 07/06/2022] [Revised: 08/16/2022] [Accepted: 08/17/2022] [Indexed: 11/02/2022]
Abstract
Lapatinib is a highly selective reversible inhibitor of the tyrosine kinase domains of HER2 and EGFR, approved for the treatment of advanced stage HER2-overexpressing breast cancers. Although targeted therapy with lapatinib provides initial clinical advantage, cancer cells' adaptive responses can overcome the inhibitory effects of lapatinib. HER3 upregulation and autocrine induction of HER3 ligand neuregulin-1 (NRG), have been implicated in the restoration of AKT and ERK1/2 activity and rescue of cell proliferation. In this study we evaluated the effects of lapatinib alone and in combination with AMPK activator GSK-621 in HER2-overexpressing breast cancer cell lines SKBR3 and BT474. Our results show that in cells exposed to lapatinib and GSK-621 in combination, lapatinib-mediated HER3 upregulation was reduced and reactivation of AKT and ERK1/2 kinases was prevented. The two drugs in combination decreased cell viability in a synergistic manner and greatly reduced the ability of NRG to rescue cell proliferation. Finally, we provide evidence that in cells exposed to lapatinib and GSK-621 in combination the establishment of a transcriptionally permissive chromatin structure at the HER3 promoter is hampered. The results of this study highlight a potential role for AMPK activation in counteracting lapatinib-induced adaptive responses of HER2-overexpressing breast cancer cells.
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Affiliation(s)
- Barbara Buccinnà
- University of Turin, Department of Oncology, via Michelangelo Buonarroti 27/b, 10126 Torino, Italy.
| | - Cristina Ramondetti
- University of Turin, Department of Oncology, via Michelangelo Buonarroti 27/b, 10126 Torino, Italy.
| | - Marco Piccinini
- University of Turin, Department of Oncology, via Michelangelo Buonarroti 27/b, 10126 Torino, Italy.
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3
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Yan W, Deng XW, Yang C, Tang X. The Genome-Wide EMS Mutagenesis Bias Correlates With Sequence Context and Chromatin Structure in Rice. FRONTIERS IN PLANT SCIENCE 2021; 12:579675. [PMID: 33841451 PMCID: PMC8025102 DOI: 10.3389/fpls.2021.579675] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Accepted: 02/17/2021] [Indexed: 06/12/2023]
Abstract
Ethyl methanesulfonate (EMS) is a chemical mutagen believed to mainly induce G/C to A/T transitions randomly in plant genomes. However, mutant screening for phenotypes often gets multiple alleles for one gene but no mutant for other genes. We investigated the potential EMS mutagenesis bias and the possible correlations with sequence context and chromatin structure using the whole genome resequencing data collected from 52 rice EMS mutants. We defined the EMS-induced single nucleotide polymorphic sites (SNPs) and explored the genomic factors associated with EMS mutagenesis bias. Compared with natural SNPs presented in the Rice3K project, EMS showed a preference on G/C sites with flanking sequences also higher in GC contents. The composition of local dinucleotides and trinucleotides was also associated with the efficiency of EMS mutagenesis. The biased distribution of EMS-induced SNPs was positively correlated with CpG numbers, transposable element contents, and repressive epigenetic markers but negatively with gene expression, the euchromatin marker DNase I hypersensitive sites, and active epigenetic markers, suggesting that sequence context and chromatin structure might correlate with the efficiency of EMS mutagenesis. Exploring the genome-wide features of EMS mutagenesis and correlations with epigenetic modifications will help in the understanding of DNA repair mechanism.
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Affiliation(s)
- Wei Yan
- Guangdong Provincial Key Laboratory of Biotechnology for Plant Development, School of Life Sciences, South China Normal University, Guangzhou, China
- Shenzhen Institute of Molecular Crop Design, Shenzhen, China
| | - Xing Wang Deng
- Shenzhen Institute of Molecular Crop Design, Shenzhen, China
- School of Life Sciences, Southern University of Science and Technology, Shenzhen, China
| | - Chengwei Yang
- Guangdong Provincial Key Laboratory of Biotechnology for Plant Development, School of Life Sciences, South China Normal University, Guangzhou, China
| | - Xiaoyan Tang
- Guangdong Provincial Key Laboratory of Biotechnology for Plant Development, School of Life Sciences, South China Normal University, Guangzhou, China
- Shenzhen Institute of Molecular Crop Design, Shenzhen, China
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4
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Yoshihara R, Mitomi Y, Okada M, Shibata H, Tanokami M, Nakajima Y, Inui H, Oono Y, Furudate H, Tanaka S. Effects of Arabidopsis Ku80 deletion on the integration of the left border of T-DNA into plant chromosomal DNA via Agrobacterium tumefaciens. Genes Genet Syst 2020; 95:173-182. [PMID: 32848122 DOI: 10.1266/ggs.19-00064] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
T-DNA integration into plant chromosomal DNA via Agrobacterium tumefaciens can be achieved by exploiting the double-strand break repair system of the host's DNA. However, the detailed mechanism of T-DNA integration remains unclear. Here, a sequence analysis of the junction sequences of T-DNA and chromosomal DNA was performed to assess the mechanism of T-DNA integration. T-DNA was introduced into Arabidopsis wild-type and NHEJ-deficient ku80 mutant plants using the floral dip method; the junctions of the left border (LB) of T-DNA were subsequently analyzed by adapter PCR. The most frequent junction of the LB of T-DNA with chromosomal DNA was of the filler DNA type in both lines. The lengths of direct or inverted repeat sequences within or around the filler DNA sequence were greater in the ku80 mutant. In addition, the frequency of T-DNA integration near a transcription start site was significantly higher in the ku80 mutant. Our observations suggest that the presence of the Ku80 protein affects the location of the integration of T-DNA and the pattern of formation of repeat sequences within or around the filler DNA during LB integration into chromosomal DNA.
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Affiliation(s)
- Ryouhei Yoshihara
- Department of Regulatory Biology, Faculty of Science, Saitama University
| | - Yuka Mitomi
- Department of Regulatory Biology, Faculty of Science, Saitama University
| | - Maki Okada
- Department of Regulatory Biology, Faculty of Science, Saitama University
| | - Hanako Shibata
- Department of Regulatory Biology, Faculty of Science, Saitama University
| | - Mai Tanokami
- Department of Regulatory Biology, Faculty of Science, Saitama University
| | - Yurie Nakajima
- Department of Regulatory Biology, Faculty of Science, Saitama University
| | | | - Yutaka Oono
- Takasaki Advanced Radiation Research Institute, National Institutes for Quantum and Radiological Science and Technology
| | - Hiroyuki Furudate
- Department of Regulatory Biology, Faculty of Science, Saitama University
| | - Shuuitsu Tanaka
- Department of Regulatory Biology, Faculty of Science, Saitama University
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5
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Formaldehyde-assisted isolation of regulatory DNA elements from Arabidopsis leaves. Nat Protoc 2020; 15:713-733. [PMID: 32042178 DOI: 10.1038/s41596-019-0277-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Accepted: 12/03/2019] [Indexed: 12/14/2022]
Abstract
Eukaryotic gene transcription is associated with the eviction of nucleosomes and the formation of open chromatin, which enables the recruitment of transcriptional coactivators and other regulatory factors. Open chromatin is thus a hallmark of functional regulatory DNA elements in genomes. In recent years, formaldehyde-assisted isolation of regulatory elements (FAIRE) has proven powerful in identifying open chromatin in the genome of various eukaryotes, particularly yeast, human, and mouse. However, it has proven challenging to adapt the FAIRE protocol for use on plant material, and the few available protocols all have their drawbacks (e.g., applicability only to specific developmental stages). In this Protocol Extension, we describe a reliable FAIRE protocol for mature Arabidopsis (Arabidopsis thaliana) leaves that adapts the original protocol for use on plants. The main differences between this protocol extension and the earlier FAIRE protocol are an increased formaldehyde concentration in the chromatin crosslinking buffer, application of a repeated vacuum to increase crosslinking efficiency, and altered composition of the DNA extraction buffer. The protocol is applicable to leaf chromatin of unstressed and stressed plants and can be completed within 1 week. Here, we also describe downstream analysis using qPCR and next-generation sequencing. However, this Protocol Extension should also be compatible with downstream hybridization to a DNA microarray. In addition, it is likely that only minor adaptations will be necessary to apply this protocol to other Arabidopsis organs or plant species.
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Abstract
cis-regulatory DNA elements (CREs) are noncoding but functional DNA sequences. The binding of regulatory proteins into CRE regions leads to chromatin high sensitive to DNase I digestion, which are termed as DNase I hypersensitive sites (DHSs). These DHSs can be efficiently detected through DNase I digestion followed by high-throughput DNA sequencing (DNase-seq). Thus, DNase-seq has become a powerful technique for DHSs mapping at whole-genome level in both plants and animals. Here we describe a DNase-seq procedure modified and developed for crop plants. These plants usually contain large amounts of repetitive sequences and complex organic constituents. With the main improvement in nuclei isolation, this method has been successfully used in mapping DHSs in cotton and sugarcane.
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7
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Chen Y, Chen A. Unveiling the gene regulatory landscape in diseases through the identification of DNase I-hypersensitive sites. Biomed Rep 2019; 11:87-97. [PMID: 31423302 PMCID: PMC6684942 DOI: 10.3892/br.2019.1233] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Accepted: 07/03/2019] [Indexed: 01/18/2023] Open
Abstract
DNase I-hypersensitive sites (DHSs) serve key roles in the regulation of gene transcription as markers of cis-regulatory elements (CREs). Recent advances in next-generation sequencing have enabled the genome-wide location and annotation of DHSs in a variety of cells. Numerous studies have confirmed that DHSs are involved in several processes in cell fate decision and development. DHSs have also been indicated in cancer and inherited diseases as driver distal regulatory elements. Here, the definition of DHSs is reviewed, in addition to high-throughput methods of DHS identification. Furthermore, the function of DHSs in gene expression is probed. The roles of DHSs in disease occurrence are also reviewed and discussed. Concomitant advances in the identification of essential roles of DHSs will assist in disclosing the underlying molecular mechanisms, supplementing gene transcription and enlarging the molecular basis of DHS-related bioprocesses, phenotypes, distinct traits and diseases.
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Affiliation(s)
- Ying Chen
- Central Laboratory, The Affiliated Wuxi Maternity and Child Health Care Hospital of Nanjing Medical University, Wuxi, Jiangsu 214002, P.R. China
| | - Ailing Chen
- Central Laboratory, The Affiliated Wuxi Maternity and Child Health Care Hospital of Nanjing Medical University, Wuxi, Jiangsu 214002, P.R. China
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8
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Chen A, Chen D, Chen Y. Advances of DNase-seq for mapping active gene regulatory elements across the genome in animals. Gene 2018; 667:83-94. [DOI: 10.1016/j.gene.2018.05.033] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2017] [Revised: 05/04/2018] [Accepted: 05/10/2018] [Indexed: 12/16/2022]
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9
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Manavalan B, Shin TH, Lee G. DHSpred: support-vector-machine-based human DNase I hypersensitive sites prediction using the optimal features selected by random forest. Oncotarget 2018; 9:1944-1956. [PMID: 29416743 PMCID: PMC5788611 DOI: 10.18632/oncotarget.23099] [Citation(s) in RCA: 77] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2017] [Accepted: 11/17/2017] [Indexed: 12/20/2022] Open
Abstract
DNase I hypersensitive sites (DHSs) are genomic regions that provide important information regarding the presence of transcriptional regulatory elements and the state of chromatin. Therefore, identifying DHSs in uncharacterized DNA sequences is crucial for understanding their biological functions and mechanisms. Although many experimental methods have been proposed to identify DHSs, they have proven to be expensive for genome-wide application. Therefore, it is necessary to develop computational methods for DHS prediction. In this study, we proposed a support vector machine (SVM)-based method for predicting DHSs, called DHSpred (DNase I Hypersensitive Site predictor in human DNA sequences), which was trained with 174 optimal features. The optimal combination of features was identified from a large set that included nucleotide composition and di- and trinucleotide physicochemical properties, using a random forest algorithm. DHSpred achieved a Matthews correlation coefficient and accuracy of 0.660 and 0.871, respectively, which were 3% higher than those of control SVM predictors trained with non-optimized features, indicating the efficiency of the feature selection method. Furthermore, the performance of DHSpred was superior to that of state-of-the-art predictors. An online prediction server has been developed to assist the scientific community, and is freely available at: http://www.thegleelab.org/DHSpred.html.
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Affiliation(s)
| | - Tae Hwan Shin
- Department of Physiology, Ajou University School of Medicine, Suwon, Republic of Korea
- Institute of Molecular Science and Technology, Ajou University, Suwon, Republic of Korea
| | - Gwang Lee
- Department of Physiology, Ajou University School of Medicine, Suwon, Republic of Korea
- Institute of Molecular Science and Technology, Ajou University, Suwon, Republic of Korea
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10
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Tannenbaum M, Sarusi-Portuguez A, Krispil R, Schwartz M, Loza O, Benichou JIC, Mosquna A, Hakim O. Regulatory chromatin landscape in Arabidopsis thaliana roots uncovered by coupling INTACT and ATAC-seq. PLANT METHODS 2018; 14:113. [PMID: 30598689 PMCID: PMC6300899 DOI: 10.1186/s13007-018-0381-9] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2018] [Accepted: 12/10/2018] [Indexed: 05/19/2023]
Abstract
BACKGROUND There is a growing interest in the role of chromatin in acquiring and maintaining cell identity. Despite the ever-growing availability of genome-wide gene expression data, understanding how transcription programs are established and regulated to define cell identity remains a puzzle. An important mechanism of gene regulation is the binding of transcription factors (TFs) to specific DNA sequence motifs across the genome. However, these sequences are hindered by the packaging of DNA to chromatin. Thus, the accessibility of these loci for TF binding is highly regulated and determines where and when TFs bind. We present a workflow for measuring chromatin accessibility in Arabidopsis thaliana and define organ-specific regulatory sites and binding motifs of TFs at these sites. RESULTS We coupled the recently described isolation of nuclei tagged in specific cell types (INTACT) and assay for transposase-accessible chromatin with high-throughput sequencing (ATAC-seq) as a genome-wide strategy to uncover accessible regulatory sites in Arabidopsis based on their accessibility to nuclease digestion. By applying this pipeline in Arabidopsis roots, we revealed 41,419 accessible sites, of which approximately half are found in gene promoters and contain the H3K4me3 active histone mark. The root-unique accessible sites from this group are enriched for root processes. Interestingly, most of the root-unique accessible sites are found in nongenic regions but are correlated with root-specific expression of distant genes. Importantly, these gene-distant sites are enriched for binding motifs of TFs important for root development as well as motifs for TFs that may play a role as novel transcriptional regulators in roots, suggesting that these accessible loci are functional novel gene-distant regulatory elements. CONCLUSIONS By coupling INTACT with ATAC-seq methods, we present a feasible pipeline to profile accessible chromatin in plants. We also introduce a rapid measure of the experiment quality. We find that chromatin accessibility at promoter regions is strongly associated with transcription and active histone marks. However, root-specific chromatin accessibility is primarily found at intergenic regions, suggesting their predominance in defining organ identity possibly via long-range chromatin interactions. This workflow can be rapidly applied to study the regulatory landscape in other cell types, plant species and conditions.
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Affiliation(s)
- Miriam Tannenbaum
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, Israel
| | - Avital Sarusi-Portuguez
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, Israel
| | - Ronen Krispil
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, Israel
| | - Michal Schwartz
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, Israel
| | - Olga Loza
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, Israel
| | - Jennifer I. C. Benichou
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, Israel
| | - Assaf Mosquna
- Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, Faculty of Agriculture, Hebrew University of Jerusalem, Rehovot, Israel
| | - Ofir Hakim
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, Israel
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11
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Fu H, Zhang X. Noncoding Variants Functional Prioritization Methods Based on Predicted Regulatory Factor Binding Sites. Curr Genomics 2017; 18:322-331. [PMID: 29081688 PMCID: PMC5635616 DOI: 10.2174/1389202918666170228143619] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Revised: 10/16/2016] [Accepted: 11/02/2016] [Indexed: 12/31/2022] Open
Abstract
BACKGROUNDS With the advent of the post genomic era, the research for the genetic mechanism of the diseases has found to be increasingly depended on the studies of the genes, the gene-networks and gene-protein interaction networks. To explore gene expression and regulation, the researchers have carried out many studies on transcription factors and their binding sites (TFBSs). Based on the large amount of transcription factor binding sites predicting values in the deep learning models, further computation and analysis have been done to reveal the relationship between the gene mutation and the occurrence of the disease. It has been demonstrated that based on the deep learning methods, the performances of the prediction for the functions of the noncoding variants are outperforming than those of the conventional methods. The research on the prediction for functions of Single Nucleotide Polymorphisms (SNPs) is expected to uncover the mechanism of the gene mutation affection on traits and diseases of human beings. RESULTS We reviewed the conventional TFBSs identification methods from different perspectives. As for the deep learning methods to predict the TFBSs, we discussed the related problems, such as the raw data preprocessing, the structure design of the deep convolution neural network (CNN) and the model performance measure et al. And then we summarized the techniques that usually used in finding out the functional noncoding variants from de novo sequence. CONCLUSION Along with the rapid development of the high-throughout assays, more and more sample data and chromatin features would be conducive to improve the prediction accuracy of the deep convolution neural network for TFBSs identification. Meanwhile, getting more insights into the deep CNN framework itself has been proved useful for both the promotion on model performance and the development for more suitable design to sample data. Based on the feature values predicted by the deep CNN model, the prioritization model for functional noncoding variants would contribute to reveal the affection of gene mutation on the diseases.
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Affiliation(s)
- Haoyue Fu
- College of Sciences, Northeastern University, Shenyang, China
| | - LianpingYang
- College of Sciences, Northeastern University, Shenyang, China
- University of Southern California, Dept. Biol. Sci., Program Mol & Computat Biol, USA
| | - Xiangde Zhang
- College of Sciences, Northeastern University, Shenyang, China
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pDHS-SVM: A prediction method for plant DNase I hypersensitive sites based on support vector machine. J Theor Biol 2017; 426:126-133. [DOI: 10.1016/j.jtbi.2017.05.030] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2017] [Revised: 05/10/2017] [Accepted: 05/23/2017] [Indexed: 11/21/2022]
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13
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Laxa M. Regulatory cis-elements are located in accessible promoter regions of the CAT2 promoter and affect activating histone modifications in Arabidopsis thaliana. PLANT MOLECULAR BIOLOGY 2017; 93:49-60. [PMID: 27734290 DOI: 10.1007/s11103-016-0546-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Accepted: 09/20/2016] [Indexed: 05/24/2023]
Abstract
Catalase 2 (CAT2) plays an important role in the detoxification of hydrogen peroxide released either during photorespiration or as a consequence of biotic and abiotic stress as well as in the initiation of senescence. To date, our understanding of the regulation of CAT2 gene expression is rather poor. Chromatin immunoprecipitation experiments revealed that a wide region of the CAT2 promoter is nucleosome depleted, reflecting the ability to rapidly respond to changing environmental and stress conditions and, thus, adjusting the transcript levels of CAT2. The lowest nucleosome density was found in the region of -900 bp relative to the transcription initiation start (TIS) where two regulatory elements are located. The distance of the nucleosome depleted region to the TIS is quite unusual because the majority of nucleosome free regions are generally located in close vicinity to the 5' untranslated region. The analysis of transgenic 5' upstream deletion::gusA Arabidopsis lines showed that this region is important for the regulation of CAT2 promoter activity. To evaluate the function of the two motifs, the contribution of each element to CAT2 promoter activity was analyzed by site directed mutagenesis. The data revealed that the CAT2 promoter is regulated by the ACGT motif (Box2) rather than by the G-Box binding motif (Box1) in the vegetative phase of development. Furthermore, the presence of both Box1 and Box2 positively affected the abundance of activating histone modifications.
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Affiliation(s)
- Miriam Laxa
- Institute of Botany, Leibniz University Hannover, Herrenhaeuser Strasse 2, 30419, Hanover, Germany.
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14
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Zhang T, Marand AP, Jiang J. PlantDHS: a database for DNase I hypersensitive sites in plants. Nucleic Acids Res 2015; 44:D1148-53. [PMID: 26400163 PMCID: PMC4702941 DOI: 10.1093/nar/gkv962] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2015] [Accepted: 09/11/2015] [Indexed: 01/24/2023] Open
Abstract
Gene expression is regulated by orchestrated binding of regulatory proteins to promoters and other cis-regulatory DNA elements (CREs). Several plant databases have been developed for mapping promoters or DNA motifs associated with promoters. However, there is a lack of databases that allow investigation for all CREs. Here we present PlantDHS (http://plantdhs.org), a plant DNase I hypersensitive site (DHS) database that integrates histone modification, RNA sequencing, nucleosome positioning/occupancy, transcription factor binding sites, and genomic sequence within an easily navigated user interface. DHSs are indicative of all CREs, including promoters, enhancers, silencers, insulators and transcription factor binding sites; all of which play immense roles in global gene expression regulation. PlantDHS provides a platform to predict all CREs associated with individual genes from three model plant species, including Arabidopsis thaliana, Brachypodium distachyon and rice (Oryza sativa). PlantDHS is especially valuable in the detection of distant CREs that are located away from promoters.
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Affiliation(s)
- Tao Zhang
- Department of Horticulture, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Alexandre P Marand
- Department of Horticulture, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Jiming Jiang
- Department of Horticulture, University of Wisconsin-Madison, Madison, WI 53706, USA
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15
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Understanding Transcription Factor Regulation by Integrating Gene Expression and DNase I Hypersensitive Sites. BIOMED RESEARCH INTERNATIONAL 2015; 2015:757530. [PMID: 26425553 PMCID: PMC4573618 DOI: 10.1155/2015/757530] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/05/2014] [Accepted: 04/16/2015] [Indexed: 12/20/2022]
Abstract
Transcription factors are proteins that bind to DNA sequences to regulate gene transcription. The transcription factor binding sites are short DNA sequences (5-20 bp long) specifically bound by one or more transcription factors. The identification of transcription factor binding sites and prediction of their function continue to be challenging problems in computational biology. In this study, by integrating the DNase I hypersensitive sites with known position weight matrices in the TRANSFAC database, the transcription factor binding sites in gene regulatory region are identified. Based on the global gene expression patterns in cervical cancer HeLaS3 cell and HelaS3-ifnα4h cell (interferon treatment on HeLaS3 cell for 4 hours), we present a model-based computational approach to predict a set of transcription factors that potentially cause such differential gene expression. Significantly, 6 out 10 predicted functional factors, including IRF, IRF-2, IRF-9, IRF-1 and IRF-3, ICSBP, belong to interferon regulatory factor family and upregulate the gene expression levels responding to the interferon treatment. Another factor, ISGF-3, is also a transcriptional activator induced by interferon alpha. Using the different transcription factor binding sites selected criteria, the prediction result of our model is consistent. Our model demonstrated the potential to computationally identify the functional transcription factors in gene regulation.
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16
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Jiang J. The 'dark matter' in the plant genomes: non-coding and unannotated DNA sequences associated with open chromatin. CURRENT OPINION IN PLANT BIOLOGY 2015; 24:17-23. [PMID: 25625239 DOI: 10.1016/j.pbi.2015.01.005] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2014] [Revised: 01/12/2015] [Accepted: 01/13/2015] [Indexed: 05/03/2023]
Abstract
Sequencing of complete plant genomes has become increasingly more routine since the advent of the next-generation sequencing technology. Identification and annotation of large amounts of noncoding but functional DNA sequences, including cis-regulatory DNA elements (CREs), have become a new frontier in plant genome research. Genomic regions containing active CREs bound to regulatory proteins are hypersensitive to DNase I digestion and are called DNase I hypersensitive sites (DHSs). Several recent DHS studies in plants illustrate that DHS datasets produced by DNase I digestion followed by next-generation sequencing (DNase-seq) are highly valuable for the identification and characterization of CREs associated with plant development and responses to environmental cues. DHS-based genomic profiling has opened a door to identify and annotate the 'dark matter' in sequenced plant genomes.
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Affiliation(s)
- Jiming Jiang
- Department of Horticulture, University of Wisconsin-Madison, Madison, WI 53706, USA.
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17
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Abstract
Genomic regions associated with regulatory proteins are known to be highly sensitive to DNase I digestion and are termed DNase I hypersensitive sites (DHSs). DHSs can be identified by DNase I digestion followed by high-throughput DNA sequencing (DNase-seq). DNase-seq has become a powerful technique for genome-wide mapping of chromatin accessibility in eukaryotes with a sequenced genome. We have developed a DNase-seq procedure in plants. This procedure was adapted from the protocol originally developed for mammalian cell lines. It includes plant nuclei isolation, digestion of purified nuclei with DNase I, recovery of DNase-trimmed DNA fragments, DNase-seq library development, Illumina sequencing and data analysis. We also introduce a barcoding system for library preparation. We have conducted DNase-seq in both Arabidopsis thaliana and rice, and developed genome-wide open chromatin maps in both species. These DHS datasets have been used to detect footprints from regulatory protein binding and to reveal genome-wide nucleosome positioning patterns.
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Affiliation(s)
- Wenli Zhang
- Department of Horticulture, University of Wisconsin-Madison, 1575 Linden Drive, Madison, WI, 53706-1580, USA
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18
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Zhang W, Zhang T, Wu Y, Jiang J. Open Chromatin in Plant Genomes. Cytogenet Genome Res 2014; 143:18-27. [DOI: 10.1159/000362827] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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19
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Comparison of class 2 transposable elements at superfamily resolution reveals conserved and distinct features in cereal grass genomes. BMC Genomics 2013; 14:71. [PMID: 23369001 PMCID: PMC3579700 DOI: 10.1186/1471-2164-14-71] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2012] [Accepted: 01/29/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Class 2 transposable elements (TEs) are the predominant elements in and around plant genes where they generate significant allelic diversity. Using the complete sequences of four grasses, we have performed a novel comparative analysis of class 2 TEs. To ensure consistent comparative analyses, we re-annotated class 2 TEs in Brachypodium distachyon, Oryza sativa (rice), Sorghum bicolor and Zea mays and assigned them to one of the five cut-and-paste superfamilies found in plant genomes (Tc1/mariner, PIF/Harbinger, hAT, Mutator, CACTA). We have focused on noncoding elements because of their abundance, and compared superfamily copy number, size and genomic distribution as well as correlation with the level of nearby gene expression. RESULTS Our comparison revealed both unique and conserved features. First, the average length or size distribution of elements in each superfamily is largely conserved, with the shortest always being Tc1/mariner elements, followed by PIF/Harbinger, hAT, Mutator and CACTA. This order also holds for the ratio of the copy numbers of noncoding to coding elements. Second, with the exception of CACTAs, noncoding TEs are enriched within and flanking genes, where they display conserved distribution patterns, having the highest peak in the promoter region. Finally, our analysis of microarray data revealed that genes associated with Tc1/mariner and PIF/Harbinger noncoding elements have significantly higher expression levels than genes without class 2 TEs. In contrast, genes with CACTA elements have significantly lower expression than genes without class 2 TEs. CONCLUSIONS We have achieved the most comprehensive annotation of class 2 TEs to date in these four grass genomes. Comparative analysis of this robust dataset led to the identification of several previously unknown features of each superfamily related to copy number, element size, genomic distribution and correlation with the expression levels of nearby genes. These results highlight the importance of distinguishing TE superfamilies when assessing their impact on gene and genome evolution.
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Madrigal P, Krajewski P. Current bioinformatic approaches to identify DNase I hypersensitive sites and genomic footprints from DNase-seq data. Front Genet 2012; 3:230. [PMID: 23118738 PMCID: PMC3484326 DOI: 10.3389/fgene.2012.00230] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2012] [Accepted: 10/13/2012] [Indexed: 12/16/2022] Open
Affiliation(s)
- Pedro Madrigal
- Laboratory of Biometry, Institute of Plant Genetics, Polish Academy of Sciences Poznań, Poland
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Zhang W, Wu Y, Schnable JC, Zeng Z, Freeling M, Crawford GE, Jiang J. High-resolution mapping of open chromatin in the rice genome. Genome Res 2011; 22:151-62. [PMID: 22110044 DOI: 10.1101/gr.131342.111] [Citation(s) in RCA: 175] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Gene expression is controlled by the complex interaction of transcription factors binding to promoters and other regulatory DNA elements. One common characteristic of the genomic regions associated with regulatory proteins is a pronounced sensitivity to DNase I digestion. We generated genome-wide high-resolution maps of DNase I hypersensitive (DH) sites from both seedling and callus tissues of rice (Oryza sativa). Approximately 25% of the DH sites from both tissues were found in putative promoters, indicating that the vast majority of the gene regulatory elements in rice are not located in promoter regions. We found 58% more DH sites in the callus than in the seedling. For DH sites detected in both the seedling and callus, 31% displayed significantly different levels of DNase I sensitivity within the two tissues. Genes that are differentially expressed in the seedling and callus were frequently associated with DH sites in both tissues. The DNA sequences contained within the DH sites were hypomethylated, consistent with what is known about active gene regulatory elements. Interestingly, tissue-specific DH sites located in the promoters showed a higher level of DNA methylation than the average DNA methylation level of all the DH sites located in the promoters. A distinct elevation of H3K27me3 was associated with intergenic DH sites. These results suggest that epigenetic modifications play a role in the dynamic changes of the numbers and DNase I sensitivity of DH sites during development.
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Affiliation(s)
- Wenli Zhang
- Department of Horticulture, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
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22
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McIntosh KB, Degenhardt RF, Bonham-Smith PC. Sequence context for transcription and translation of the Arabidopsis RPL23aA and RPL23aB paralogs. Genome 2011; 54:738-51. [PMID: 21883051 DOI: 10.1139/g11-029] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The 80S cytoplasmic ribosome is responsible for translating the transcriptome into the proteome. Demand for ribosome production depends on growth rate, and both the ribosomal RNA (rRNA) and ribosomal protein (RP) components must respond coordinately and rapidly to positive and negative growth stimuli to prevent deleterious effects of excess or insufficient subunits. The 81 RPs of the Arabidopsis 80S ribosome are encoded by multigene families that often exhibit overlapping patterns of transcript accumulation; however, only one isoform of each RP family (with the exception of a small number of acidic RPs) assembles into a single ribosome. Here we dissected the regulatory regions (RRs) of both members of the RPL23a family (RPL23aA and RPL23aB) to identify salient cis-acting elements involved in transcriptional, posttranscriptional, and translational regulation of expression. Full length and truncated RRs of RPL23a paralogs were cloned upstream of a GUS reporter gene and expressed in Arabidopsis transgenic plants. High level expression in mitotically active tissues, driven by RPL23aA and RPL23aB RRs, required TATA-box, telo-box, and site II motif elements. First and second introns were found to play a minor role in posttranscriptional regulation of paralogs, and conserved transcript features (e.g., UTR base composition) may be involved in enhancing translational efficiency. Overall, our results indicate that RPL23a expression is governed by a complex network of multiple regulatory layers.
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Affiliation(s)
- Kerri B McIntosh
- Department of Biology, University of Saskatchewan, Saskatoon, Canada
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Strenkert D, Schmollinger S, Sommer F, Schulz-Raffelt M, Schroda M. Transcription factor-dependent chromatin remodeling at heat shock and copper-responsive promoters in Chlamydomonas reinhardtii. THE PLANT CELL 2011; 23:2285-301. [PMID: 21705643 PMCID: PMC3160021 DOI: 10.1105/tpc.111.085266] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2011] [Revised: 05/09/2011] [Accepted: 06/07/2011] [Indexed: 05/19/2023]
Abstract
How transcription factors affect chromatin structure to regulate gene expression in response to changes in environmental conditions is poorly understood in the green lineage. To shed light on this issue, we used chromatin immunoprecipitation and formaldehyde-assisted isolation of regulatory elements to investigate the chromatin structure at target genes of HSF1 and CRR1, key transcriptional regulators of the heat shock and copper starvation responses, respectively, in the unicellular green alga Chlamydomonas reinhardtii. Generally, we detected lower nucleosome occupancy, higher levels of histone H3/4 acetylation, and lower levels of histone H3 Lys 4 (H3K4) monomethylation at promoter regions of active genes compared with inactive promoters and transcribed and intergenic regions. Specifically, we find that activated HSF1 and CRR1 transcription factors mediate the acetylation of histones H3/4, nucleosome eviction, remodeling of the H3K4 mono- and dimethylation marks, and transcription initiation/elongation. By this, HSF1 and CRR1 quite individually remodel and activate target promoters that may be inactive and embedded into closed chromatin (HSP22F/CYC6) or weakly active and embedded into partially opened (CPX1) or completely opened chromatin (HSP70A/CRD1). We also observed HSF1-independent histone H3/4 deacetylation at the RBCS2 promoter after heat shock, suggesting interplay of specific and presumably more generally acting factors to adapt gene expression to the new requirements of a changing environment.
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van Dijk K, Ding Y, Malkaram S, Riethoven JJM, Liu R, Yang J, Laczko P, Chen H, Xia Y, Ladunga I, Avramova Z, Fromm M. Dynamic changes in genome-wide histone H3 lysine 4 methylation patterns in response to dehydration stress in Arabidopsis thaliana. BMC PLANT BIOLOGY 2010; 10:238. [PMID: 21050490 PMCID: PMC3095321 DOI: 10.1186/1471-2229-10-238] [Citation(s) in RCA: 144] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2010] [Accepted: 11/05/2010] [Indexed: 05/17/2023]
Abstract
BACKGROUND The molecular mechanisms of genome reprogramming during transcriptional responses to stress are associated with specific chromatin modifications. Available data, however, describe histone modifications only at individual plant genes induced by stress. We have no knowledge of chromatin modifications taking place at genes whose transcription has been down-regulated or on the genome-wide chromatin modification patterns that occur during the plant's response to dehydration stress. RESULTS Using chromatin immunoprecipitation and deep sequencing (ChIP-Seq) we established the whole-genome distribution patterns of histone H3 lysine 4 mono-, di-, and tri-methylation (H3K4me1, H3K4me2, and H3K4me3, respectively) in Arabidopsis thaliana during watered and dehydration stress conditions. In contrast to the relatively even distribution of H3 throughout the genome, the H3K4me1, H3K4me2, and H3K4me3 marks are predominantly located on genes. About 90% of annotated genes carry one or more of the H3K4 methylation marks. The H3K4me1 and H3K4me2 marks are more widely distributed (80% and 84%, respectively) than the H3K4me3 marks (62%), but the H3K4me2 and H3K4me1 levels changed only modestly during dehydration stress. By contrast, the H3K4me3 abundance changed robustly when transcripts levels from responding genes increased or decreased. In contrast to the prominent H3K4me3 peaks present at the 5'-ends of most transcribed genes, genes inducible by dehydration and ABA displayed atypically broader H3K4me3 distribution profiles that were present before and after the stress. CONCLUSIONS A higher number (90%) of annotated Arabidopsis genes carry one or more types of H3K4me marks than previously reported. During the response to dehydration stress the changes in H3K4me1, H3K4me2, and H3K4me3 patterns show different dynamics and specific patterns at up-regulated, down-regulated, and unaffected genes. The different behavior of each methylation mark during the response process illustrates that they have distinct roles in the transcriptional response of implicated genes. The broad H3K4me3 distribution profiles on nucleosomes of stress-induced genes uncovered a specific chromatin pattern associated with many of the genes involved in the dehydration stress response.
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Affiliation(s)
- Karin van Dijk
- Center for Biotechnology, 1901 Vine St., University of Nebraska, Lincoln, NE, 68588, USA
- Creighton University, Department of Biology, 2500 California Plaza Omaha, NE 68178, USA
| | - Yong Ding
- Center for Biotechnology, 1901 Vine St., University of Nebraska, Lincoln, NE, 68588, USA
| | - Sridhar Malkaram
- Center for Biotechnology, 1901 Vine St., University of Nebraska, Lincoln, NE, 68588, USA
| | - Jean-Jack M Riethoven
- Center for Biotechnology, 1901 Vine St., University of Nebraska, Lincoln, NE, 68588, USA
- School of Biological Sciences, University of Nebraska, Lincoln, NE, 68588, USA
| | - Rong Liu
- Center for Biotechnology, 1901 Vine St., University of Nebraska, Lincoln, NE, 68588, USA
- Department of Biomedical Engineering, University of California, Los Angeles, CA, 90095, USA
| | - Jingyi Yang
- Center for Biotechnology, 1901 Vine St., University of Nebraska, Lincoln, NE, 68588, USA
- Microsoft, One Microsoft Way, Redmond, WA 98052, USA
| | - Peter Laczko
- Center for Biotechnology, 1901 Vine St., University of Nebraska, Lincoln, NE, 68588, USA
| | - Han Chen
- Center for Biotechnology, 1901 Vine St., University of Nebraska, Lincoln, NE, 68588, USA
| | - Yuannan Xia
- Center for Biotechnology, 1901 Vine St., University of Nebraska, Lincoln, NE, 68588, USA
| | - Istvan Ladunga
- Center for Biotechnology, 1901 Vine St., University of Nebraska, Lincoln, NE, 68588, USA
- Department of Statistics, University of Nebraska, Lincoln, NE, 68588, USA
| | - Zoya Avramova
- School of Biological Sciences, University of Nebraska, Lincoln, NE, 68588, USA
| | - Michael Fromm
- Center for Biotechnology, 1901 Vine St., University of Nebraska, Lincoln, NE, 68588, USA
- Department of Agronomy & Horticulture, University of Nebraska, Lincoln, NE, 68583, USA
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Nagaya S, Kawamura K, Shinmyo A, Kato K. The HSP terminator of Arabidopsis thaliana increases gene expression in plant cells. PLANT & CELL PHYSIOLOGY 2010; 51:328-32. [PMID: 20040586 DOI: 10.1093/pcp/pcp188] [Citation(s) in RCA: 128] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
To express a foreign gene in plants effectively, a good expression system is required. Here we describe the identification of a transcriptional terminator that supports increased levels of expression. The terminators of several Arabidopsis genes were examined in transfected Arabidopsis T87 protoplasts. The heat shock protein 18.2 (HSP) terminator was the most effective in supporting increased levels of expression. The HSP terminator increases mRNA levels of both transiently and stably expressed transgenes approximately 2-fold more than the NOS (nopaline synthase) terminator. When combined with the HSP terminator, a translational enhancer increased gene expression levels approximately 60- to 100-fold in transgenic plants.
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Affiliation(s)
- Shingo Nagaya
- Graduate School of Biological Sciences, Nara Institute of Science and Technology, Ikoma, Nara, 630-0101 Japan
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26
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Filipenko EA, Deineko EV, Shumnyi VK. Specific features of T-DNA insertion regions in transgenic plants. RUSS J GENET+ 2009. [DOI: 10.1134/s1022795409110040] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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27
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Tachiki K, Kodama Y, Nakayama H, Shinmyo A. Determination of the in vivo distribution of nuclear matrix attachment regions using a polymerase chain reaction-based assay in Arabidopsis thaliana. J Biosci Bioeng 2009; 108:11-9. [PMID: 19577185 DOI: 10.1016/j.jbiosc.2009.02.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2008] [Revised: 02/07/2009] [Accepted: 02/12/2009] [Indexed: 11/18/2022]
Abstract
Matrix attachment regions (MARs) are the regions on genomic DNA that are attached to the nuclear matrix in eukaryotes. Previous in vitro and in silico MAR analyses have shown that MARs distribute at average intervals of about 5 kb on the Arabidopsis thaliana genome. However, the in vivo evidence for the distribution of MARs in A. thaliana is lacking. Therefore, we have used a polymerase chain reaction (PCR)-based method to investigate the in vivo locations of MARs across an 80 kb region of A. thaliana genome. This assay indicated that the average interval of MARs within this region is 4.7 kb (range 1 to 11 kb), well consistent with the previous in vitro and in silico MAR studies. This result suggests that average size of the chromatin loop in A. thaliana is smaller when compared with the other eukaryotes, in which the sizes are known to vary in the range from 9 to 100 kb. However, we found that the number of genes per chromatin loop (1-3 genes) in A. thaliana is similar to those found in other eukaryotes. Furthermore, as in animals' MARs, DNase I hypersensitive sites were also found in the MARs end-region in A. thaliana. Our results suggest that basic organization of chromatin loop in A. thaliana is similar to other eukaryotes in the view that it contains a few genes, and that the average size of chromatin loop in eukaryotes is possibly determined by genome structure, such as gene density and average gene size.
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Affiliation(s)
- Kensuke Tachiki
- Graduate School of Biological Sciences, Nara Institute of Science and Technology, Ikoma, Nara, 630-0192, Japan
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28
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Fedoreyeva LI, Smirnova TA, Kolomijtseva GY, Vanyushin BF. H1 histone modulates DNA hydrolysis with WEN1 and WEN2 endonucleases from wheat coleoptiles. BIOCHEMISTRY (MOSCOW) 2009; 74:145-52. [DOI: 10.1134/s0006297909020047] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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29
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Abstract
Regions of DNA that bind to the nuclear matrix, or nucleoskeleton, are known as Matrix Attachment Regions (MARs). MARs are thought to play an important role in higher-order structure and chromatin organization within the nucleus. MARs are also thought to act as boundaries of chromosomal domains that act to separate regions of gene-rich, decondensed euchromatin from highly repetitive, condensed heterochromatin. Herein I will present evidence that MARs do indeed act as domain boundaries and can prevent the spread of silencing into active genes. Many fundamental questions remain unanswered about how MARs function in the nucleus. New findings in epigenetics indicate that MARs may also play an important role in the organization of genes and the eventual transport of their mRNAs through the nuclear pore.
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30
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Degenhardt RF, Bonham-Smith PC. Transcript profiling demonstrates absence of dosage compensation in Arabidopsis following loss of a single RPL23a paralog. PLANTA 2008; 228:627-40. [PMID: 18566829 DOI: 10.1007/s00425-008-0765-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2008] [Accepted: 05/30/2008] [Indexed: 05/20/2023]
Abstract
Translation of nucleus-encoded messages in plants is conducted by the cytoplasmic ribosome, an enzyme that is comprised of two RNA/protein subunits. In Arabidopsis thaliana, the 81 different ribosomal proteins (r-proteins) of the cytosolic ribosome belong to gene families with multiple expressed members. Given that ribosomes generally contain only one copy of each r-protein, regulatory mechanisms must exist to ensure their stoichiometric accumulation. These mechanisms must be dynamic, allowing for adjustments to ribosome biogenesis to fulfill biological requirements for protein synthesis during development, and following stress induction of global changes in gene expression. In this study, we investigated whether r-protein paralogs are feedback regulated at the transcript level by obtaining a T-DNA knockout of one member, RPL23aB, from the two-member RPL23a family. Expression of the lone functional paralog in this line, RPL23aA, was compared to the expression of both paralogs in wildtype plants under non-stressed, low temperature-, and high light stresses. RPL23aA expression was not upregulated in RPL23aB knockouts to compensate for paralog-loss, and consequently knockouts showed reduced total abundance of RPL23a transcripts. However, no phenotype developed in RPL23aB knockouts, suggesting that this paralog is dispensable under experimental conditions examined, or that compensation by RPL23aA may occur post-transcriptionally. Patterns of RPL23aA and RPL23aB transcript accumulation in wildtype plants suggest that paralogs respond coordinately to developmental and stress stimuli.
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Affiliation(s)
- Rory F Degenhardt
- Department of Biology, University of Saskatchewan, Saskatoon, SK, Canada, S7N 5E2.
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Matsuura H, Shinmyo A, Kato K. Preferential translation mediated by Hsp81-3 5'-UTR during heat shock involves ribosome entry at the 5'-end rather than an internal site in Arabidopsis suspension cells. J Biosci Bioeng 2008; 105:39-47. [PMID: 18295718 DOI: 10.1263/jbb.105.39] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2007] [Accepted: 10/11/2007] [Indexed: 11/17/2022]
Abstract
Translational inhibition of most mRNAs and preferential translation of mRNAs coding heat shock proteins (Hsps) occur in most cells under heat shock stress. For most Hsp mRNAs, preferential translation in heat-shocked cells is conferred by their 5'-untranslated regions (5'-UTRs). However, the preferential translation directed by 5'-UTRs during heat shock remains mostly unknown in plants. Here, we found that the mRNA of Hsp81-3, which is an Arabidopsis Hsp90 family gene, continued to be associated with polysomes in heat-shocked Arabidopsis suspension-cultured cells. The Hsp81-3 5'-UTR was found to contribute to the efficient translation of capped reporter mRNAs in heat-shocked Arabidopsis protoplasts using a transient expression assay. Further characterization of the Hsp81-3 5'-UTR revealed that the anterior half of the 5'-UTR is important for the efficient translation in heat-shocked protoplasts. Moreover, the Hsp81-3 5'-UTR was highly capable of enhancing translation from uncapped reporter mRNAs relative to the 5'-UTR of a housekeeping gene in both normal and heat-shocked protoplasts. These Hsp81-3 5'-UTR-directed translations both in capped and uncapped reporter mRNAs were substantially reduced by the insertion of an upstream AUG at the 5'-end of the 5'-UTR, indicating that ribosomes are recruited to the 5'-end of the Hsp81-3 5'-UTR regardless of temperature and the presence or absence of the cap structure. These results suggest that the preferential translation of Hsp81-3 mRNA in heat-shocked Arabidopsis cells involves a ribosome scanning from the 5'-end of the 5'-UTR rather than ribosome entry to the internal site.
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Affiliation(s)
- Hideyuki Matsuura
- Graduate School of Biological Sciences, Nara Institute of Science and Technology, Ikoma, Nara, Japan
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