1
|
Wu Z, Gong H, Zhou Z, Jiang T, Lin Z, Li J, Xiao S, Yang B, Huang L. Mapping short tandem repeats for liver gene expression traits helps prioritize potential causal variants for complex traits in pigs. J Anim Sci Biotechnol 2022; 13:8. [PMID: 35034641 PMCID: PMC8762894 DOI: 10.1186/s40104-021-00658-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Accepted: 11/25/2021] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND Short tandem repeats (STRs) were recently found to have significant impacts on gene expression and diseases in humans, but their roles on gene expression and complex traits in pigs remain unexplored. This study investigates the effects of STRs on gene expression in liver tissues based on the whole-genome sequences and RNA-Seq data of a discovery cohort of 260 F6 individuals and a validation population of 296 F7 individuals from a heterogeneous population generated from crosses among eight pig breeds. RESULTS We identified 5203 and 5868 significantly expression STRs (eSTRs, FDR < 1%) in the F6 and F7 populations, respectively, most of which could be reciprocally validated (π1 = 0.92). The eSTRs explained 27.5% of the cis-heritability of gene expression traits on average. We further identified 235 and 298 fine-mapped STRs through the Bayesian fine-mapping approach in the F6 and F7 pigs, respectively, which were significantly enriched in intron, ATAC peak, compartment A and H3K4me3 regions. We identified 20 fine-mapped STRs located in 100 kb windows upstream and downstream of published complex trait-associated SNPs, which colocalized with epigenetic markers such as H3K27ac and ATAC peaks. These included eSTR of the CLPB, PGLS, PSMD6 and DHDH genes, which are linked with genome-wide association study (GWAS) SNPs for blood-related traits, leg conformation, growth-related traits, and meat quality traits, respectively. CONCLUSIONS This study provides insights into the effects of STRs on gene expression traits. The identified eSTRs are valuable resources for prioritizing causal STRs for complex traits in pigs.
Collapse
Affiliation(s)
- Zhongzi Wu
- State Key Laboratory for Pig Genetic Improvement and Production Technology, Jiangxi Agricultural University, Nanchang, China
| | - Huanfa Gong
- State Key Laboratory for Pig Genetic Improvement and Production Technology, Jiangxi Agricultural University, Nanchang, China
| | - Zhimin Zhou
- State Key Laboratory for Pig Genetic Improvement and Production Technology, Jiangxi Agricultural University, Nanchang, China
| | - Tao Jiang
- State Key Laboratory for Pig Genetic Improvement and Production Technology, Jiangxi Agricultural University, Nanchang, China
| | - Ziqi Lin
- State Key Laboratory for Pig Genetic Improvement and Production Technology, Jiangxi Agricultural University, Nanchang, China
| | - Jing Li
- State Key Laboratory for Pig Genetic Improvement and Production Technology, Jiangxi Agricultural University, Nanchang, China
| | - Shijun Xiao
- State Key Laboratory for Pig Genetic Improvement and Production Technology, Jiangxi Agricultural University, Nanchang, China
| | - Bin Yang
- State Key Laboratory for Pig Genetic Improvement and Production Technology, Jiangxi Agricultural University, Nanchang, China.
| | - Lusheng Huang
- State Key Laboratory for Pig Genetic Improvement and Production Technology, Jiangxi Agricultural University, Nanchang, China.
| |
Collapse
|
2
|
Katsumata K, Ichikawa Y, Fuse T, Kurumizaka H, Yanagida A, Urano T, Kato H, Shimizu M. Sequence-dependent nucleosome formation in trinucleotide repeats evaluated by in vivo chemical mapping. Biochem Biophys Res Commun 2021; 556:179-184. [PMID: 33839413 DOI: 10.1016/j.bbrc.2021.03.155] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2021] [Accepted: 03/28/2021] [Indexed: 11/18/2022]
Abstract
Trinucleotide repeat sequences (TRSs), consisting of 10 unique classes of repeats in DNA, are members of microsatellites and abundantly and non-randomly distributed in many eukaryotic genomes. The lengths of TRSs are mutable, and the expansions of several TRSs are implicated in hereditary neurological diseases. However, the underlying causes of the biased distribution and the dynamic properties of TRSs in the genome remain elusive. Here, we examined the effects of TRSs on nucleosome formation in vivo by histone H4-S47C site-directed chemical cleavages, using well-defined yeast minichromosomes in which each of the ten TRS classes resided in the central region of a positioned nucleosome. We showed that (AAT)12 and (ACT)12 act as strong nucleosome-promoting sequences, while (AGG)12 and (CCG)12 act as nucleosome-excluding sequences in vivo. The local histone binding affinity scores support the idea that nucleosome formation in TRSs, except for (AGG)12, is mainly determined by the affinity for the histone octamers. Overall, our study presents a framework for understanding the nucleosome-forming abilities of TRSs.
Collapse
Affiliation(s)
- Koji Katsumata
- Department of Chemistry, Graduate School of Science and Engineering, Meisei University, 2-1-1 Hodokubo, Hino, Tokyo, 191-8506, Japan
| | - Yuichi Ichikawa
- Division of Cancer Biology, The Cancer Institute of JFCR, 3-8-31 Ariake, Koto-ku, Tokyo, 135-8550, Japan
| | - Tomohiro Fuse
- Department of Chemistry, Graduate School of Science and Engineering, Meisei University, 2-1-1 Hodokubo, Hino, Tokyo, 191-8506, Japan
| | - Hitoshi Kurumizaka
- Laboratory of Chromatin Structure and Function, Institute for Quantitative Biosciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-0032, Japan
| | - Akio Yanagida
- School of Pharmacy, Tokyo University of Pharmacy and Life Sciences, 1432-1 Horinouchi, Hachioji, Tokyo, 192-0392, Japan
| | - Takeshi Urano
- Department of Biochemistry, Shimane University School of Medicine, 89-1 Enya-cho, Izumo, Shimane, 693-8501, Japan
| | - Hiroaki Kato
- Department of Biochemistry, Shimane University School of Medicine, 89-1 Enya-cho, Izumo, Shimane, 693-8501, Japan
| | - Mitsuhiro Shimizu
- Department of Chemistry, Graduate School of Science and Engineering, Meisei University, 2-1-1 Hodokubo, Hino, Tokyo, 191-8506, Japan.
| |
Collapse
|
3
|
Luo D, Kato D, Nogami J, Ohkawa Y, Kurumizaka H, Kono H. MNase, as a probe to study the sequence-dependent site exposures in the +1 nucleosomes of yeast. Nucleic Acids Res 2019; 46:7124-7137. [PMID: 29893974 PMCID: PMC6101533 DOI: 10.1093/nar/gky502] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2017] [Accepted: 05/30/2018] [Indexed: 01/06/2023] Open
Abstract
The first nucleosomes in the downstream of transcription starting sites are called +1 nucleosomes, which are expected to be readily unwrapped for DNA transcription. To investigate DNA accessibility in +1 nucleosomes, MNase-seq experiments were carried out with 20 reconstituted +1 nucleosomes of budding yeast. Although MNase has been known for its sequence preference in DNA digestions, we confirmed that this sequence preference is overwhelmed by DNA accessibility by identifying the sequence-driven and accessibility-driven cleavages. Specifically, we find that sequences favoured by MNase at the end regions such as TA dinucleotide are prohibited from cleavage at the internal sites in the early stage of digestion. Nevertheless, sequences less favoured by MNase at the end regions such as AA/TT dinucleotide are predominantly cleaved at the internal sites in the early stage of digestion. Since AA/TT is known as a rigid dinucleotide step resistant to DNA bending, these internal cleavages reflect the local site exposures induced by DNA mechanics. As the DNA entry site of +1 nucleosomes in yeast is found AA/TT-rich, this sequence element may play a role in gene activation by reducing DNA–histone affinities along the direction of DNA transcription.
Collapse
Affiliation(s)
- Di Luo
- Molecular Modeling and Simulation Group, Department of Quantum Beam Life Science, National Institutes for Quantum and Radiological Science and Technology, Kizugawa, Kyoto 619-0215, Japan
| | - Daiki Kato
- Laboratory of Structural Biology, Graduate School of Advanced Science and Engineering, Waseda University, 2-2 Wakamatsu-cho, Shinjuku-ku, Tokyo 162-8480, Japan
| | - Jumpei Nogami
- Division of Transcriptomics, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
| | - Yasuyuki Ohkawa
- Division of Transcriptomics, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
| | - Hitoshi Kurumizaka
- Laboratory of Structural Biology, Graduate School of Advanced Science and Engineering, Waseda University, 2-2 Wakamatsu-cho, Shinjuku-ku, Tokyo 162-8480, Japan
| | - Hidetoshi Kono
- Molecular Modeling and Simulation Group, Department of Quantum Beam Life Science, National Institutes for Quantum and Radiological Science and Technology, Kizugawa, Kyoto 619-0215, Japan
| |
Collapse
|
4
|
Fuse T, Yanagida A, Shimizu M. The Yeast Minichromosome System Consisting of Highly Positioned Nucleosomes in Vivo. Biol Pharm Bull 2019; 42:289-294. [DOI: 10.1248/bpb.b18-00732] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- Tomohiro Fuse
- Department of Chemistry, Graduate School of Science and Engineering, Program in Chemistry and Life Science, School of Science and Engineering, Meisei University
| | - Akio Yanagida
- School of Pharmacy, Tokyo University of Pharmacy and Life Sciences
| | - Mitsuhiro Shimizu
- Department of Chemistry, Graduate School of Science and Engineering, Program in Chemistry and Life Science, School of Science and Engineering, Meisei University
| |
Collapse
|
5
|
Fuse T, Katsumata K, Morohoshi K, Mukai Y, Ichikawa Y, Kurumizaka H, Yanagida A, Urano T, Kato H, Shimizu M. Parallel mapping with site-directed hydroxyl radicals and micrococcal nuclease reveals structural features of positioned nucleosomes in vivo. PLoS One 2017; 12:e0186974. [PMID: 29073207 PMCID: PMC5658119 DOI: 10.1371/journal.pone.0186974] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Accepted: 10/11/2017] [Indexed: 12/17/2022] Open
Abstract
Micrococcal nuclease (MNase) has been widely used for analyses of nucleosome locations in many organisms. However, due to its sequence preference, the interpretations of the positions and occupancies of nucleosomes using MNase have remained controversial. Next-generation sequencing (NGS) has also been utilized for analyses of MNase-digests, but some technical biases are commonly present in the NGS experiments. Here, we established a gel-based method to map nucleosome positions in Saccharomyces cerevisiae, using isolated nuclei as the substrate for the histone H4 S47C-site-directed chemical cleavage in parallel with MNase digestion. The parallel mapping allowed us to compare the chemically and enzymatically cleaved sites by indirect end-labeling and primer extension mapping, and thus we could determine the nucleosome positions and the sizes of the nucleosome-free regions (or nucleosome-depleted regions) more accurately, as compared to nucleosome mapping by MNase alone. The analysis also revealed that the structural features of the nucleosomes flanked by the nucleosome-free region were different from those within regularly arrayed nucleosomes, showing that the structures and dynamics of individual nucleosomes strongly depend on their locations. Moreover, we demonstrated that the parallel mapping results were generally consistent with the previous genome-wide chemical mapping and MNase-Seq results. Thus, the gel-based parallel mapping will be useful for the analysis of a specific locus under various conditions.
Collapse
Affiliation(s)
- Tomohiro Fuse
- Department of Chemistry, Graduate School of Science and Engineering, Program in Chemistry and Life Science, School of Science and Engineering, Meisei University, Hino, Tokyo, Japan
| | - Koji Katsumata
- Department of Chemistry, Graduate School of Science and Engineering, Program in Chemistry and Life Science, School of Science and Engineering, Meisei University, Hino, Tokyo, Japan
| | - Koya Morohoshi
- Department of Chemistry, Graduate School of Science and Engineering, Program in Chemistry and Life Science, School of Science and Engineering, Meisei University, Hino, Tokyo, Japan
| | - Yukio Mukai
- Department of Bioscience, Faculty of Bioscience, Nagahama Institute of Bio-Science and Technology, Nagahama, Shiga, Japan
| | - Yuichi Ichikawa
- Graduate School of Advanced Science and Engineering/RISE/IMSB, Waseda University, Shinjuku-ku, Tokyo, Japan
| | - Hitoshi Kurumizaka
- Graduate School of Advanced Science and Engineering/RISE/IMSB, Waseda University, Shinjuku-ku, Tokyo, Japan
| | - Akio Yanagida
- School of Pharmacy, Tokyo University of Pharmacy and Life Science, Hachioji, Tokyo, Japan
| | - Takeshi Urano
- Department of Biochemistry, Shimane University School of Medicine, Izumo, Shimane, Japan
| | - Hiroaki Kato
- Department of Biochemistry, Shimane University School of Medicine, Izumo, Shimane, Japan
| | - Mitsuhiro Shimizu
- Department of Chemistry, Graduate School of Science and Engineering, Program in Chemistry and Life Science, School of Science and Engineering, Meisei University, Hino, Tokyo, Japan
- * E-mail:
| |
Collapse
|
6
|
Adrian AB, Corchado JC, Comeron JM. Predictive Models of Recombination Rate Variation across the Drosophila melanogaster Genome. Genome Biol Evol 2016; 8:2597-612. [PMID: 27492232 PMCID: PMC5010912 DOI: 10.1093/gbe/evw181] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
In all eukaryotic species examined, meiotic recombination, and crossovers in particular, occur non‐randomly along chromosomes. The cause for this non-random distribution remains poorly understood but some specific DNA sequence motifs have been shown to be enriched near crossover hotspots in a number of species. We present analyses using machine learning algorithms to investigate whether DNA motif distribution across the genome can be used to predict crossover variation in Drosophila melanogaster, a species without hotspots. Our study exposes a combinatorial non-linear influence of motif presence able to account for a significant fraction of the genome-wide variation in crossover rates at all genomic scales investigated, from 20% at 5-kb to almost 70% at 2,500-kb scale. The models are particularly predictive for regions with the highest and lowest crossover rates and remain highly informative after removing sub-telomeric and -centromeric regions known to have strongly reduced crossover rates. Transcriptional activity during early meiosis and differences in motif use between autosomes and the X chromosome add to the predictive power of the models. Moreover, we show that population-specific differences in crossover rates can be partly explained by differences in motif presence. Our results suggest that crossover distribution in Drosophila is influenced by both meiosis-specific chromatin dynamics and very local constitutive open chromatin associated with DNA motifs that prevent nucleosome stabilization. These findings provide new information on the genetic factors influencing variation in recombination rates and a baseline to study epigenetic mechanisms responsible for plastic recombination as response to different biotic and abiotic conditions and stresses.
Collapse
Affiliation(s)
| | | | - Josep M Comeron
- Department of Biology, University of Iowa Interdisciplinary Graduate Program in Genetics, University of Iowa
| |
Collapse
|
7
|
Ichikawa Y, Morohashi N, Tomita N, Mitchell AP, Kurumizaka H, Shimizu M. Sequence-directed nucleosome-depletion is sufficient to activate transcription from a yeast core promoter in vivo. Biochem Biophys Res Commun 2016; 476:57-62. [PMID: 27208777 DOI: 10.1016/j.bbrc.2016.05.063] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2016] [Accepted: 05/12/2016] [Indexed: 11/18/2022]
Abstract
Nucleosome-depleted regions (NDRs) (also called nucleosome-free regions or NFRs) are often found in the promoter regions of many yeast genes, and are formed by multiple mechanisms, including the binding of activators and enhancers, the actions of chromatin remodeling complexes, and the specific DNA sequences themselves. However, it remains unclear whether NDR formation per se is essential for transcriptional activation. Here, we examined the relationship between nucleosome organization and gene expression using a defined yeast reporter system, consisting of the CYC1 minimal core promoter and the lacZ gene. We introduced simple repeated sequences that should be either incorporated in nucleosomes or excluded from nucleosomes in the site upstream of the TATA boxes. The (CTG)12, (GAA)12 and (TGTAGG)6 inserts were incorporated into a positioned nucleosome in the core promoter region, and did not affect the reporter gene expression. In contrast, the insertion of (CGG)12, (TTAGGG)6, (A)34 or (CG)8 induced lacZ expression by 10-20 fold. Nucleosome mapping analyses revealed that the inserts that induced the reporter gene expression prevented nucleosome formation, and created an NDR upstream of the TATA boxes. Thus, our results demonstrated that NDR formation dictated by DNA sequences is sufficient for transcriptional activation from the core promoter in vivo.
Collapse
Affiliation(s)
- Yuichi Ichikawa
- Graduate School of Advanced Science and Engineering/RISE, Waseda University, 2-2 Wakamatsu-cho, Shinjuku-ku, Tokyo 162-8640, Japan; Department of Biological Sciences, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, PA 15213, USA
| | - Nobuyuki Morohashi
- Program in Chemistry and Life Science, School of Science and Engineering, Department of Chemistry, Graduate School of Science and Engineering, Meisei University, 2-1-1 Hodokubo, Hino, Tokyo 191-8506, Japan
| | - Nobuyuki Tomita
- Program in Chemistry and Life Science, School of Science and Engineering, Department of Chemistry, Graduate School of Science and Engineering, Meisei University, 2-1-1 Hodokubo, Hino, Tokyo 191-8506, Japan
| | - Aaron P Mitchell
- Department of Biological Sciences, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, PA 15213, USA
| | - Hitoshi Kurumizaka
- Graduate School of Advanced Science and Engineering/RISE, Waseda University, 2-2 Wakamatsu-cho, Shinjuku-ku, Tokyo 162-8640, Japan
| | - Mitsuhiro Shimizu
- Program in Chemistry and Life Science, School of Science and Engineering, Department of Chemistry, Graduate School of Science and Engineering, Meisei University, 2-1-1 Hodokubo, Hino, Tokyo 191-8506, Japan.
| |
Collapse
|
8
|
Ichikawa Y, Nishimura Y, Kurumizaka H, Shimizu M. Nucleosome organization and chromatin dynamics in telomeres. Biomol Concepts 2016; 6:67-75. [PMID: 25720088 DOI: 10.1515/bmc-2014-0035] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Accepted: 12/01/2014] [Indexed: 11/15/2022] Open
Abstract
Telomeres are DNA-protein complexes located at the ends of linear eukaryotic chromosomes, and are essential for chromosome stability and maintenance. In most organisms, telomeres consist of tandemly repeated sequences of guanine-clusters. In higher eukaryotes, most of the telomeric repeat regions are tightly packaged into nucleosomes, even though telomeric repeats act as nucleosome-disfavoring sequences. Although telomeres were considered to be condensed heterochromatin structures, recent studies revealed that the chromatin structures in telomeres are actually dynamic. The dynamic properties of telomeric chromatin are considered to be important for the structural changes between the euchromatic and heterochromatic states during the cell cycle and in cellular differentiation. We propose that the nucleosome-disfavoring property of telomeric repeats is a crucial determinant for the lability of telomeric nucleosomes, and provides a platform for chromatin dynamics in telomeres. Furthermore, we discuss the influences of telomeric components on the nucleosome organization and chromatin dynamics in telomeres.
Collapse
|
9
|
Abe H, Gemmell NJ. Abundance, arrangement, and function of sequence motifs in the chicken promoters. BMC Genomics 2014; 15:900. [PMID: 25318583 PMCID: PMC4203960 DOI: 10.1186/1471-2164-15-900] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2014] [Accepted: 10/08/2014] [Indexed: 01/01/2023] Open
Abstract
Background Eukaryotic promoters are regions containing various sequence motifs necessary to control gene transcription. Much evidence has emerged showing that structural and/or contextual changes in regulatory elements can critically affect cis-regulatory activity. As sequence motifs can be key factors in maintaining complex promoter architectures, one effective approach to further understand the evolution of promoter regions in vertebrates is to compare the abundance and distribution patterns of sequence motifs in these regions between divergent species. When compared with mammals, the chicken (Gallus gallus) has a very different genome composition and sufficient genomic information to make it a good model for the exploration of promoter structure and evolution. Results More than 10% of chicken genes contained short tandem repeat (STR) in the region 2 kb upstream of promoters, but the total number of STRs observed in chicken is approximately half of that detected in human promoters. In terms of the STR motif frequencies, chicken promoter regions were more similar to other avian and mammalian promoters than these were to the entire chicken genome. Unlike other STRs, nearly half of the trinucleotide repeats found in promoters partly or entirely overlapped with CpG islands, indicating potential association with nucleosome positions. Moreover, the chicken promoters are abundant with sequence motifs such as poly-A, poly-G and G-quadruplexes, especially in the core region, that are otherwise rare in the genome. Most of sequence motifs showed strong functional enrichment for particular gene ontology (GO) categories, indicating roles in regulation of transcription and gene expression, as well as immune response and cognition. Conclusions Chicken promoter regions share some, but not all, of the structural features observed in mammalian promoters. The findings presented here provide empirical evidence suggesting that the frequencies and locations of STR motifs have been conserved through promoter evolution in a lineage-specific manner. Correlation analysis between GO categories and sequence motifs suggests motif-specific constraints acting on gene function. Electronic supplementary material The online version of this article (doi:10.1186/1471-2164-15-900) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- Hideaki Abe
- Department of Anatomy, University of Otago, Dunedin, New Zealand.
| | | |
Collapse
|
10
|
Chiba S, Tsuchiya N, Horikawa Y, Narita S, Inoue T, Akihama S, Saito M, Numakura K, Tsuruta H, Huang M, Satoh S, Habuchi T. Functional mononucleotide repeat polymorphism in the promoter region of HGF is associated with risk and malignant aggressiveness of bladder cancer. Int J Oncol 2013; 44:678-84. [PMID: 24366484 DOI: 10.3892/ijo.2013.2221] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2013] [Accepted: 11/18/2013] [Indexed: 11/05/2022] Open
Abstract
Increased expression of hepatocyte growth factor (HGF) has been shown to be associated with aggressiveness in several types of cancer. Shorter variants of deoxyadenosine tract element (DATE) located in the HGF promoter region have been reported to enhance the expression of HGF. In this study, we investigated the role of HGF DATE variants in bladder cancer risk, HGF expression and clinicopathological features. The frequency of individuals with a short DATE (<28 repeats) in peripheral blood lymphocytes (PBLs) was significantly higher in bladder cancer patients compared to controls (p<0.001). Somatic mutations were observed in 37 of 70 bladder tumor (BT) tissues and the frequency of mutation to long DATE was significantly higher than that to short DATE (p=0.047). The presence of the short DATE in BT tissue was significantly associated with higher tumor grade (p=0.015). HGF mRNA levels were significantly higher in pT2 tumors than pTa or pT1 tumors (p=0.019), and in grade 3 tumors than grade 1 or 2 tumors (p=0.020). Furthermore, BT tissues with the short DATE showed significantly higher levels of HGF mRNA (p<0.001). In patients who underwent radical cystectomy, those with higher HGF expression had a significantly shorter overall survival than those with lower HGF expression (p=0.012). In conclusion, HGF may be associated with the prognosis of patients who undergo radical cystectomy, and the HGF DATE may affect the risk and aggressiveness of bladder cancer by altering HGF expression.
Collapse
Affiliation(s)
- Syuji Chiba
- Department of Urology, Akita University Graduate School of Medicine, Akita, Japan
| | - Norihiko Tsuchiya
- Department of Urology, Akita University Graduate School of Medicine, Akita, Japan
| | - Yohei Horikawa
- Department of Urology, Akita University Graduate School of Medicine, Akita, Japan
| | - Shintaro Narita
- Department of Urology, Akita University Graduate School of Medicine, Akita, Japan
| | - Takamitsu Inoue
- Department of Urology, Akita University Graduate School of Medicine, Akita, Japan
| | - Susumu Akihama
- Department of Urology, Akita University Graduate School of Medicine, Akita, Japan
| | - Mitsuru Saito
- Department of Urology, Akita University Graduate School of Medicine, Akita, Japan
| | - Kazuyuki Numakura
- Department of Urology, Akita University Graduate School of Medicine, Akita, Japan
| | - Hiroshi Tsuruta
- Department of Urology, Akita University Graduate School of Medicine, Akita, Japan
| | - Mingguo Huang
- Department of Urology, Akita University Graduate School of Medicine, Akita, Japan
| | - Shigeru Satoh
- Department of Urology, Akita University Graduate School of Medicine, Akita, Japan
| | - Tomonori Habuchi
- Department of Urology, Akita University Graduate School of Medicine, Akita, Japan
| |
Collapse
|
11
|
Ichikawa Y, Morohashi N, Nishimura Y, Kurumizaka H, Shimizu M. Telomeric repeats act as nucleosome-disfavouring sequences in vivo. Nucleic Acids Res 2013; 42:1541-52. [PMID: 24174540 PMCID: PMC3919577 DOI: 10.1093/nar/gkt1006] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Telomeric DNAs consist of tandem repeats of G-clusters such as TTAGGG and TG1-3, which are the human and yeast repeat sequences, respectively. In the yeast Saccharomyces cerevisiae, the telomeric repeats are non-nucleosomal, whereas in humans, they are organized in tightly packaged nucleosomes. However, previous in vitro studies revealed that the binding affinities of human and yeast telomeric repeat sequences to histone octamers in vitro were similar, which is apparently inconsistent with the differences in the human and yeast telomeric chromatin structures. To further investigate the relationship between telomeric sequences and chromatin structure, we examined the effect of telomeric repeats on the formation of positioned nucleosomes in vivo by indirect end-label mapping, primer extension mapping and nucleosome repeat analyses, using a defined minichromosome in yeast cells. We found that the human and yeast telomeric repeat sequences both disfavour nucleosome assembly and alter nucleosome positioning in the yeast minichromosome. We further demonstrated that the G-clusters in the telomeric repeats are required for the nucleosome-disfavouring properties. Thus, our results suggest that this inherent structural feature of the telomeric repeat sequences is involved in the functional dynamics of the telomeric chromatin structure.
Collapse
Affiliation(s)
- Yuichi Ichikawa
- Laboratory of Structural Biology, Graduate School of Advanced Science and Engineering/RISE, Waseda University, 2-2 Wakamatsu-cho, Shinjuku-ku, Tokyo 162-8640, Japan, Program in Chemistry and Life Science, School of Science and Engineering, Department of Chemistry, Graduate School of Science and Engineering, Meisei University, 2-1-1 Hodokubo, Hino, Tokyo 191-8506, Japan and Graduate School of Medical Life Science, Yokohama City University, 1-7-29 Suehiro-cho, Tsurumi-ku, Yokohama 230-0045, Japan
| | | | | | | | | |
Collapse
|
12
|
Tan BG, Vijgenboom E, Worrall JAR. Conformational and thermodynamic hallmarks of DNA operator site specificity in the copper sensitive operon repressor from Streptomyces lividans. Nucleic Acids Res 2013; 42:1326-40. [PMID: 24121681 PMCID: PMC3902906 DOI: 10.1093/nar/gkt902] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Metal ion homeostasis in bacteria relies on metalloregulatory proteins to upregulate metal resistance genes and enable the organism to preclude metal toxicity. The copper sensitive operon repressor (CsoR) family is widely distributed in bacteria and controls the expression of copper efflux systems. CsoR operator sites consist of G-tract containing pseudopalindromes of which the mechanism of operator binding is poorly understood. Here, we use a structurally characterized CsoR from Streptomyces lividans (CsoRSl) together with three specific operator targets to reveal the salient features pertaining to the mechanism of DNA binding. We reveal that CsoRSl binds to its operator site through a 2-fold axis of symmetry centred on a conserved 5′-TAC/GTA-3′ inverted repeat. Operator recognition is stringently dependent not only on electropositive residues but also on a conserved polar glutamine residue. Thermodynamic and circular dichroic signatures of the CsoRSl–DNA interaction suggest selectivity towards the A-DNA-like topology of the G-tracts at the operator site. Such properties are enhanced on protein binding thus enabling the symmetrical binding of two CsoRSl tetramers. Finally, differential binding modes may exist in operator sites having more than one 5′-TAC/GTA-3′ inverted repeat with implications in vivo for a mechanism of modular control.
Collapse
Affiliation(s)
- Benedict G Tan
- School of Biological Science, University of Essex, Wivenhoe Park, Colchester, CO4 3SQ, UK and Molecular Biotechnology, Institute of Biology Leiden, Sylvius Laboratory, Leiden University, PO Box 9505, 2300 RA Leiden, The Netherlands
| | | | | |
Collapse
|
13
|
Grandi FC, An W. Non-LTR retrotransposons and microsatellites: Partners in genomic variation. Mob Genet Elements 2013; 3:e25674. [PMID: 24195012 PMCID: PMC3812793 DOI: 10.4161/mge.25674] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2013] [Revised: 07/07/2013] [Accepted: 07/09/2013] [Indexed: 01/10/2023] Open
Abstract
The human genome is laden with both non-LTR (long-terminal repeat) retrotransposons and microsatellite repeats. Both types of sequences are able to, either actively or passively, mutagenize the genomes of human individuals and are therefore poised to dynamically alter the human genomic landscape across generations. Non-LTR retrotransposons, such as L1 and Alu, are a major source of new microsatellites, which are born both concurrently and subsequently to L1 and Alu integration into the genome. Likewise, the mutation dynamics of microsatellite repeats have a direct impact on the fitness of their non-LTR retrotransposon parent owing to microsatellite expansion and contraction. This review explores the interactions and dynamics between non-LTR retrotransposons and microsatellites in the context of genomic variation and evolution.
Collapse
Affiliation(s)
- Fiorella C Grandi
- School of Molecular Biosciences and Center for Reproductive Biology; Washington State University; Pullman, WA USA
| | | |
Collapse
|
14
|
Promoter microsatellites as modulators of human gene expression. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 769:41-54. [PMID: 23560304 DOI: 10.1007/978-1-4614-5434-2_4] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Microsatellites in and around genes have been shown to modulate levels of gene expression in multiple organisms, ranging from bacteria to humans. Here we will discuss promoter microsatellites known to modulate gene expression, with a few key examples related to the human brain. Many of the microsatellites we discuss are highly conserved in mammals, indicating that selection may favor their retention as "tuning knobs" of gene expression. We will also discuss the mechanisms by which microsatellites in promoters can alter gene expression as they expand and contract, with particular attention to secondary structures like Z-DNA and H-DNA. We suggest that promoter microsatellites, especially those that are highly conserved, may be an important source of human phenotypic variation.
Collapse
|
15
|
Xiao H, Mizuguchi G, Wisniewski J, Huang Y, Wei D, Wu C. Nonhistone Scm3 binds to AT-rich DNA to organize atypical centromeric nucleosome of budding yeast. Mol Cell 2011; 43:369-80. [PMID: 21816344 DOI: 10.1016/j.molcel.2011.07.009] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2010] [Revised: 03/29/2011] [Accepted: 07/18/2011] [Indexed: 10/17/2022]
Abstract
The molecular architecture of centromere-specific nucleosomes containing histone variant CenH3 is controversial. We have biochemically reconstituted two distinct populations of nucleosomes containing Saccharomyces cerevisiae CenH3 (Cse4). Reconstitution of octameric nucleosomes containing histones Cse4/H4/H2A/H2B is robust on noncentromere DNA, but inefficient on AT-rich centromere DNA. However, nonhistone Scm3, which is required for Cse4 deposition in vivo, facilitates in vitro reconstitution of Cse4/H4/Scm3 complexes on AT-rich centromere sequences. Scm3 has a nonspecific DNA binding domain that shows preference for AT-rich DNA and a histone chaperone domain that promotes specific loading of Cse4/H4. In live cells, Scm3-GFP is enriched at centromeres in all cell cycle phases. Chromatin immunoprecipitation confirms that Scm3 occupies centromere DNA throughout the cell cycle, even when Cse4 and H4 are temporarily dislodged in S phase. These findings suggest a model in which centromere-bound Scm3 aids recruitment of Cse4/H4 to assemble and maintain an H2A/H2B-deficient centromeric nucleosome.
Collapse
Affiliation(s)
- Hua Xiao
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, Bethesda, MD 20892-4260, USA
| | | | | | | | | | | |
Collapse
|
16
|
Takagi H, Inai Y, Watanabe SI, Tatemoto S, Yajima M, Akasaka K, Yamamoto T, Sakamoto N. Nucleosome exclusion from the interspecies-conserved central AT-rich region of the Ars insulator. J Biochem 2011; 151:75-87. [PMID: 21930654 DOI: 10.1093/jb/mvr118] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The Ars insulator is a boundary element identified in the upstream region of the arylsulfatase (HpArs) gene in the sea urchin, Hemicentrotus pulcherrimus, and possesses the ability to both block enhancer-promoter communications and protect transgenes from silent chromatin. To understand the molecular mechanism of the Ars insulator, we investigated the correlation between chromatin structure, DNA structure and insulator activity. Nuclease digestion of nuclei isolated from sea urchin embryos revealed the presence of a nuclease-hypersensitive site within the Ars insulator. Analysis of micrococcal nuclease-sensitive sites in the Ars insulator, reconstituted with nucleosomes, showed the exclusion of nucleosomes from the central AT-rich region. Furthermore, the central AT-rich region in naked DNA was sensitive to nucleotide base modification by diethylpyrocarbonate (DEPC). These observations suggest that non-B-DNA structures in the central AT-rich region may inhibit nucleosomal formation, which leads to nuclease hypersensitivity. Furthermore, comparison of nucleotide sequences between the HpArs gene and its ortholog in Strongylocentrotus purpuratus revealed that the central AT-rich region of the Ars insulator is conserved, and this conserved region showed significant enhancer blocking activity. These results suggest that the central AT-rich nucleosome-free region plays an important role in the function of the Ars insulator.
Collapse
Affiliation(s)
- Haruna Takagi
- Department of Mathematical and Life Sciences, Graduate School of Science, Hiroshima University, Higashi-Hiroshima 739-8526, Japan
| | | | | | | | | | | | | | | |
Collapse
|
17
|
Abstract
Sequence-specific transcription factors (TFs) play a central role in regulating transcription initiation by directing the recruitment and activity of the general transcription machinery and accessory factors. It is now well established that many of the effects exerted by TFs in eukaryotes are mediated through interactions with a host of coregulators that modify the chromatin state, resulting in a more open (in case of activation) or closed conformation (in case of repression). The relationship between TFs and chromatin is a two-way street, however, as chromatin can in turn influence the recognition and binding of target sequences by TFs. The aim of this chapter is to highlight how this dynamic interplay between TF-directed remodelling of chromatin and chromatin-adjusted targeting of TF binding determines where and how transcription is initiated, and to what degree it is productive.
Collapse
|
18
|
Miki K, Shimizu M, Fujii M, Takayama S, Hossain MN, Ayusawa D. 5-bromodeoxyuridine induces transcription of repressed genes with disruption of nucleosome positioning. FEBS J 2010; 277:4539-48. [PMID: 21040474 DOI: 10.1111/j.1742-4658.2010.07868.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
5-Bromodeoxyuridine (BrdU) modulates the expression of particular genes associated with cellular differentiation and senescence when incorporated into DNA instead of thymidine (dThd). To date, a molecular mechanism for this phenomenon remains a mystery in spite of a large number of studies. Recently, we have demonstrated that BrdU disrupts nucleosome positioning on model plasmids mediated by specific AT-tracts in yeast cells. Here we constructed a cognate plasmid that can form an ordered array of nucleosomes determined by an α2 operator and contains the BAR1 gene as an expression marker gene to examine BAR1 expression in dThd-auxotrophic MATα cells under various conditions. In medium containing dThd, BAR1 expression was completely repressed, associated with the formation of the stable array of nucleosomes. Insertion of AT-tracts into a site of the promoter region slightly increased BAR1 expression and slightly destabilized nucleosome positioning dependent on their sequence specificity. In medium containing BrdU, BAR1 expression was further enhanced, associated with more marked disruption of nucleosome positioning on the promoter region. Disruption of nucleosome positioning seems to be sufficient for full expression of the marker gene if necessary transcription factors are supplied. Incorporation of 5-bromouracil into the plasmid did not weaken the binding of the α2/Mcm1 repressor complex to its legitimate binding site, as revealed by an in vivo UV photofootprinting assay. These results suggest that BrdU increases transcription of repressed genes by disruption of nucleosome positioning around their promoters.
Collapse
Affiliation(s)
- Kensuke Miki
- Department of Genome System Science, Yokohama City University, Yokohama, Kanagawa, Japan
| | | | | | | | | | | |
Collapse
|
19
|
Tanaka Y, Yamashita R, Suzuki Y, Nakai K. Effects of Alu elements on global nucleosome positioning in the human genome. BMC Genomics 2010; 11:309. [PMID: 20478020 PMCID: PMC2878307 DOI: 10.1186/1471-2164-11-309] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2009] [Accepted: 05/17/2010] [Indexed: 11/14/2022] Open
Abstract
Background Understanding the genome sequence-specific positioning of nucleosomes is essential to understand various cellular processes, such as transcriptional regulation and replication. As a typical example, the 10-bp periodicity of AA/TT and GC dinucleotides has been reported in several species, but it is still unclear whether this feature can be observed in the whole genomes of all eukaryotes. Results With Fourier analysis, we found that this is not the case: 84-bp and 167-bp periodicities are prevalent in primates. The 167-bp periodicity is intriguing because it is almost equal to the sum of the lengths of a nucleosomal unit and its linker region. After masking Alu elements, these periodicities were greatly diminished. Next, using two independent large-scale sets of nucleosome mapping data, we analyzed the distribution of nucleosomes in the vicinity of Alu elements and showed that (1) there are one or two fixed slot(s) for nucleosome positioning within the Alu element and (2) the positioning of neighboring nucleosomes seems to be in phase, more or less, with the presence of Alu elements. Furthermore, (3) these effects of Alu elements on nucleosome positioning are consistent with inactivation of promoter activity in Alu elements. Conclusions Our discoveries suggest that the principle governing nucleosome positioning differs greatly across species and that the Alu family is an important factor in primate genomes.
Collapse
Affiliation(s)
- Yoshiaki Tanaka
- Department of Medical Genome Sciences, University of Tokyo, Minato-ku, Japan
| | | | | | | |
Collapse
|
20
|
Tanase JI, Morohashi N, Fujita M, Nishikawa JI, Shimizu M, Ohyama T. Highly efficient chromatin transcription induced by superhelically curved DNA segments: the underlying mechanism revealed by a yeast system. Biochemistry 2010; 49:2351-8. [PMID: 20166733 DOI: 10.1021/bi901950w] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Superhelically curved DNA structures can strongly activate transcription in mammalian cells. However, the mechanism underlying the activation has not been clarified. We investigated this mechanism in yeast cells, using 108, 180, and 252 bp synthetic curved DNA segments. Even in the presence of nucleosomes, these DNAs activated transcription from a UAS-deleted CYC1 promoter that is silenced in the presence of nucleosomes. The fold-activations of transcription by these segments, relative to the transcription on the control that lacked such segments, were 51.4, 63.4, and 56.4, respectively. The superhelically curved DNA structures favored nucleosome formation. However, the translational positions of the nucleosomes were dynamic. The high mobility of the nucleosomes on the superhelically curved DNA structures seemed to influence the mobility of the nucleosomes formed on the promoter and eventually enhanced the access to the center region of one TATA sequence. Functioning as a dock for the histone core and allowing nucleosome sliding seem to be the mechanisms underlying the transcriptional activation by superhelically curved DNA structures in chromatin. The present study provides important clues for designing and constructing artificial chromatin modulators, as a tool for chromatin engineering.
Collapse
Affiliation(s)
- Jun-ichi Tanase
- Department of Biology, Faculty of Education and Integrated Arts and Sciences, Waseda University, 2-2 Wakamatsu-cho, Shinjuku-ku, Tokyo 162-8480, Japan
| | | | | | | | | | | |
Collapse
|
21
|
Effects of non-B DNA sequences on transgene expression. J Biosci Bioeng 2009; 108:20-3. [PMID: 19577186 DOI: 10.1016/j.jbiosc.2009.02.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2009] [Revised: 02/13/2009] [Accepted: 02/16/2009] [Indexed: 11/21/2022]
Abstract
DNA conformation may be an important factor affecting gene transcription. In this study, we examined how DNA sequences with unusual conformations affect transgene expression. A(30) and (CG)(15) sequences that can adopt the B' and Z conformations, respectively, were introduced into a beta-actin promoter. Luciferase plasmids containing the manipulated promoter were transfected into NIH3T3 cells by electroporation and were delivered into mouse livers with a hydrodynamics-based injection. Expression from plasmid with the (CG)(15) sequence was multiple times higher than expression from control plasmid DNA. The A(30) sequence also tended to enhance expression. These results suggest that non-B DNA sequences could improve transgene expression in cells.
Collapse
|
22
|
Abstract
AbstractShort runs of adenines are a ubiquitous DNA element in regulatory regions of many organisms. When runs of 4–6 adenine base pairs (‘A-tracts’) are repeated with the helical periodicity, they give rise to global curvature of the DNA double helix, which can be macroscopically characterized by anomalously slow migration on polyacrylamide gels. The molecular structure of these DNA tracts is unusual and distinct from that of canonical B-DNA. We review here our current knowledge about the molecular details of A-tract structure and its interaction with sequences flanking them of either side and with the environment. Various molecular models were proposed to describe A-tract structure and how it causes global deflection of the DNA helical axis. We review old and recent findings that enable us to amalgamate the various findings to one model that conforms to the experimental data. Sequences containing phased repeats of A-tracts have from the very beginning been synonymous with global intrinsic DNA bending. In this review, we show that very often it is the unique structure of A-tracts that is at the basis of their widespread occurrence in regulatory regions of many organisms. Thus, the biological importance of A-tracts may often be residing in their distinct structure rather than in the global curvature that they induce on sequences containing them.
Collapse
|
23
|
Ma J, DeFrances MC, Zou C, Johnson C, Ferrell R, Zarnegar R. Somatic mutation and functional polymorphism of a novel regulatory element in the HGF gene promoter causes its aberrant expression in human breast cancer. J Clin Invest 2009; 119:478-91. [PMID: 19188684 DOI: 10.1172/jci36640] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2008] [Accepted: 12/10/2008] [Indexed: 11/17/2022] Open
Abstract
The HGF gene is transcriptionally silenced in normal differentiated breast epithelial cells, but its repression fails to occur in mammary carcinoma tissues and cell lines. The molecular mechanisms underpinning aberrant HGF expression in breast cancer cells are unknown. Here we report the discovery of a DNA element located 750 bp upstream from the transcription start site in the human HGF promoter that acts as a transcriptional repressor and is a target of deletion mutagenesis in human breast cancer cells and tissues. This HGF promoter element consists of a mononucleotide repeat of 30 deoxyadenosines (30As), which we have termed "deoxyadenosine tract element" (DATE). Functional studies revealed that truncation mutations within DATE have profound local and global effects on the HGF promoter region by modulating chromatin structure and DNA-protein interactions, leading to constitutive activation of the HGF promoter in human breast carcinoma cell lines. We found that 51% of African Americans and 15% of individuals of mixed European descent with breast cancer harbor a truncated DATE variant (25As or fewer) in their breast tumors and that the truncated allele is associated with cancer incidence and aberrant HGF expression. Notably, breast cancer patients with the truncated DATE variant are substantially younger than those with a wild-type genotype. We also suggest that DATE may be used as a potential genetic marker to identify individuals with a higher risk of developing breast cancer.
Collapse
Affiliation(s)
- Jihong Ma
- Division of Experimental Pathology, Department of Pathology, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, USA
| | | | | | | | | | | |
Collapse
|
24
|
Segal E, Widom J. Poly(dA:dT) tracts: major determinants of nucleosome organization. Curr Opin Struct Biol 2009; 19:65-71. [PMID: 19208466 PMCID: PMC2673466 DOI: 10.1016/j.sbi.2009.01.004] [Citation(s) in RCA: 311] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2009] [Accepted: 01/16/2009] [Indexed: 11/27/2022]
Abstract
Homopolymeric stretches of deoxyadenosine nucleotides (A's) on one strand of double-stranded DNA, referred to as poly(dA:dT) tracts or A-tracts, are overabundant in eukaryotic genomes. They have unusual structural, dynamic, and mechanical properties, and may resist sharp bending. Such unusual material properties, together with their overabundance in eukaryotes, raised the possibility that poly(dA:dT) tracts might function in eukaryotes to influence the organization of nucleosomes at many genomic regions. Recent genome-wide studies strongly confirm these ideas and suggest that these tracts play major roles in chromatin organization and genome function. Here we review what is known about poly(dA:dT) tracts and how they work.
Collapse
Affiliation(s)
- Eran Segal
- Department of Computer Science and Applied Mathematics, Weizmann Institute of Science, Rehovot, 76100, Israel
| | - Jonathan Widom
- Department of Biochemistry, Molecular Biology, and Cell Biology, Northwestern University, 2205 Tech Drive, Evanston, IL 60208-3500 USA
| |
Collapse
|
25
|
UEDA TOYOTOSHI, HARA MASANORI, ODAGAWA IKUMI, SHIGIHARA TAKANORI. Simultaneous Treatment of Washing, Disinfection and Sterilization Using Ultrasonic Levitation, Silver Electrolysis and Ozone Oxidation. Biocontrol Sci 2009; 14:1-12. [DOI: 10.4265/bio.14.1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022]
|
26
|
Travers A, Caserta M, Churcher M, Hiriart E, Di Mauro E. Nucleosome positioning—what do we really know? MOLECULAR BIOSYSTEMS 2009; 5:1582-92. [DOI: 10.1039/b907227f] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
27
|
Endoh M, Kobayashi Y, Yamakami Y, Yonekura R, Fujii M, Ayusawa D. Coordinate expression of the human pregnancy-specific glycoprotein gene family during induced and replicative senescence. Biogerontology 2008; 10:213-21. [PMID: 18792801 DOI: 10.1007/s10522-008-9173-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2008] [Accepted: 08/18/2008] [Indexed: 10/21/2022]
Abstract
Pregnancy-specific glycoproteins (PSGs) comprise a family of highly similar polypeptides encoded by 11 transcriptionally active genes that compactly cluster on band 19q13.2. All members of the PSG family were found to be markedly up-regulated by addition of 5-bromodeoxyuridine in HeLa cells. Similarly, all of the members were markedly up-regulated during replicative senescence in normal human fibroblasts. Promoter analysis of the PSG1, 4, and 11 genes in HeLa cells did not reveal a cis-regulatory element responsive to 5-bromodeoxyuridine in their 5'-flanking sequences. These results suggest that the PSG genes are regulated at a level of higher order chromatin structure besides by a signal of pregnancy.
Collapse
Affiliation(s)
- Morio Endoh
- International Graduate School of Arts and Sciences, Yokohama City University, Seto 22-2, Kanazawa-ku, Yokohama, Kanagawa, 236-0027, Japan
| | | | | | | | | | | |
Collapse
|
28
|
Morohashi N, Nakajima K, Kuwana S, Tachiwana H, Kurumizaka H, Shimizu M. In vivo and in vitro footprinting of nucleosomes and transcriptional activators using an infrared-fluorescence DNA sequencer. Biol Pharm Bull 2008; 31:187-92. [PMID: 18239271 DOI: 10.1248/bpb.31.187] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The analysis of nucleosome positions and transcription factor binding in chromatin is a central issue for understanding the mechanisms of gene expression in eukaryotes. Here, we have developed a footprinting technique, using multi-cycle primer extension with an infrared-fluorescence DNA sequencer, to analyze chromatin structure in isolated yeast nuclei and transcriptional activator binding in living yeast cells. Using this technique, the binding of the yeast activators Hap1 and Hap2/3/4/5 to their cognate sites was detectable as hypersensitive sites by in vivo UV-photofootprinting, and the locations of nucleosomes in yeast minichromosomes were determined by micrococcal nuclease mapping. We also applied this method to determine the position of the nucleosome in the 5S DNA fragment reconstituted in vitro. This technique allowed us to eliminate the use of radioactive materials and to perform experiments on common benches. Thus, the footprinting procedure established in this study will be useful to researchers studying DNA-protein interactions and chromatin structure in vivo and in vitro.
Collapse
Affiliation(s)
- Nobuyuki Morohashi
- Department of Chemistry, Graduate School of Science and Engineering, Meisei University, Hino, Tokyo, Japan
| | | | | | | | | | | |
Collapse
|
29
|
Lettieri T, Kraehenbuehl R, Capiaghi C, Livingstone-Zatchej M, Thoma F. Functionally distinct nucleosome-free regions in yeast require Rad7 and Rad16 for nucleotide excision repair. DNA Repair (Amst) 2008; 7:734-43. [PMID: 18329964 DOI: 10.1016/j.dnarep.2008.01.016] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2008] [Accepted: 01/23/2008] [Indexed: 11/16/2022]
Abstract
In yeast, Rad7 and Rad16 are two proteins required for nucleotide excision repair (NER) of non-transcribed chromatin. They have roles in damage recognition, in the postincision steps of NER, and in ultraviolet-light-dependent histone H3 acetylation. Moreover, Rad16 is an ATP-ase of the SNF2 superfamily and therefore might facilitate chromatin repair by nucleosome remodelling. Here, we used yeast rad7 Delta rad16 Delta mutants and show that Rad7-Rad16 is also required for NER of UV-lesions in three functionally distinct nucleosome-free regions (NFRs), the promoter and 3'-end of the URA3 gene and the ARS1 origin of replication. Moreover, rapid repair of UV-lesions by photolyase confirmed that nucleosomes were absent and that neither UV-damage formation nor rad7 Delta rad16 Delta mutations altered chromatin accessibility in NFRs. The data are consistent with a role of Rad7-Rad16 in damage recognition and processing in absence of nucleosomes. An additional role in nucleosome remodelling is discussed.
Collapse
Affiliation(s)
- Teresa Lettieri
- Institute of Cell Biology, ETH Zurich, Schafmattstrasse 18, CH-8093 Zurich, Switzerland.
| | | | | | | | | |
Collapse
|
30
|
5-Bromouracil disrupts nucleosome positioning by inducing A-form-like DNA conformation in yeast cells. Biochem Biophys Res Commun 2008; 368:662-9. [PMID: 18258180 DOI: 10.1016/j.bbrc.2008.01.149] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2008] [Accepted: 01/26/2008] [Indexed: 11/23/2022]
Abstract
5-Bromodeoxyuridine (BrdU) modulates expression of particular genes associated with cellular differentiation and senescence. Our previous studies have suggested an involvement of chromatin structure in this phenomenon. Here, we examined the effect of 5-bromouracil on nucleosome positioning in vivo using TALS plasmid in yeast cells. This plasmid can stably and precisely be assembled nucleosomes aided by the alpha2 repressor complex bound to its alpha2 operator. Insertion of AT-rich sequences into a site near the operator destabilized nucleosome positioning dependent on their length and sequences. Addition of BrdU almost completely disrupted nucleosome positioning through specific AT-tracts. The effective AT-rich sequences migrated faster on polyacrylamide gel electrophoresis, and their mobility was further accelerated by substitution of thymine with 5-bromouracil. Since this property is indicative of a rigid conformation of DNA, our results suggest that 5-bromouracil disrupts nucleosome positioning by inducing A-form-like DNA.
Collapse
|
31
|
Morohashi N, Nakajima K, Kurihara D, Mukai Y, Mitchell AP, Shimizu M. A nucleosome positioned by alpha2/Mcm1 prevents Hap1 activator binding in vivo. Biochem Biophys Res Commun 2007; 364:583-8. [PMID: 17959145 DOI: 10.1016/j.bbrc.2007.10.037] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2007] [Accepted: 10/09/2007] [Indexed: 11/24/2022]
Abstract
Nucleosome positioning has been proposed as a mechanism of transcriptional repression. Here, we examined whether nucleosome positioning affects activator binding in living yeast cells. We introduced the cognate Hap1 binding site (UAS1) at a location 24-43 bp, 29-48 bp, or 61-80 bp interior to the edge of a nucleosome positioned by alpha2/Mcm1 in yeast minichromosomes. Hap1 binding to the UAS1 was severely inhibited, not only at the pseudo-dyad but also in the peripheral region of the positioned nucleosome in alpha cells, while it was detectable in a cells, in which the nucleosomes were not positioned. Hap1 binding was restored in alpha cells with tup1 or isw2 mutations, which caused the loss of nucleosome positioning. These results support the mechanism in which alpha2/Mcm1-dependent nucleosome positioning has a regulatory function to limit the access of transcription factors.
Collapse
Affiliation(s)
- Nobuyuki Morohashi
- Department of Chemistry, Meisei University, 2-1-1 Hodokubo, Hino, Tokyo 191-8506, Japan
| | | | | | | | | | | |
Collapse
|
32
|
Zhang H, Reese JC. Exposing the core promoter is sufficient to activate transcription and alter coactivator requirement at RNR3. Proc Natl Acad Sci U S A 2007; 104:8833-8. [PMID: 17502614 PMCID: PMC1885588 DOI: 10.1073/pnas.0701666104] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Chromatin is a formidable barrier to transcription. Nucleosome density is lowest over the regulatory regions of active genes, and many repressed genes have a tightly positioned nucleosome over their core promoter. However, it has not been shown that nucleosome positioning is sufficient for repression or whether disrupting a core promoter nucleosome specifically can activate gene expression in the absence of activating signals. Here we show that disrupting the nucleosome over the core promoter of RNR3 is sufficient to drive preinitiation complex assembly and activate transcription in the absence of activating signals. Remodeling of chromatin over the RNR3 promoter requires the recruitment of the SWI/SNF complex by the general transcription factor TFIID. We found that disrupting the nucleosome over the RNR3 core promoter relieves its dependence on TFIID and SWI/SNF, indicating a functional link between these two complexes. These results suggest that the specific function of TAF(II)s is to direct the chromatin remodeling step through SWI/SNF recruitment, and not core promoter selectivity. Our results indicate that nucleosome placement plays a dominant role in repression and that the ability of the core promoter to position a nucleosome is a major determinant in TAF(II) dependency of genes in vivo.
Collapse
Affiliation(s)
- Hesheng Zhang
- Department of Biochemistry and Molecular Biology, Center for Gene Regulation, Pennsylvania State University, University Park, PA 16802
| | - Joseph C. Reese
- Department of Biochemistry and Molecular Biology, Center for Gene Regulation, Pennsylvania State University, University Park, PA 16802
- *To whom correspondence should be addressed. E-mail:
| |
Collapse
|
33
|
Yang C, Bolotin E, Jiang T, Sladek FM, Martinez E. Prevalence of the initiator over the TATA box in human and yeast genes and identification of DNA motifs enriched in human TATA-less core promoters. Gene 2006; 389:52-65. [PMID: 17123746 PMCID: PMC1955227 DOI: 10.1016/j.gene.2006.09.029] [Citation(s) in RCA: 255] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2006] [Revised: 09/12/2006] [Accepted: 09/22/2006] [Indexed: 10/24/2022]
Abstract
The core promoter of eukaryotic genes is the minimal DNA region that recruits the basal transcription machinery to direct efficient and accurate transcription initiation. The fraction of human and yeast genes that contain specific core promoter elements such as the TATA box and the initiator (INR) remains unclear and core promoter motifs specific for TATA-less genes remain to be identified. Here, we present genome-scale computational analyses indicating that approximately 76% of human core promoters lack TATA-like elements, have a high GC content, and are enriched in Sp1-binding sites. We further identify two motifs - M3 (SCGGAAGY) and M22 (TGCGCANK) - that occur preferentially in human TATA-less core promoters. About 24% of human genes have a TATA-like element and their promoters are generally AT-rich; however, only approximately 10% of these TATA-containing promoters have the canonical TATA box (TATAWAWR). In contrast, approximately 46% of human core promoters contain the consensus INR (YYANWYY) and approximately 30% are INR-containing TATA-less genes. Significantly, approximately 46% of human promoters lack both TATA-like and consensus INR elements. Surprisingly, mammalian-type INR sequences are present - and tend to cluster - in the transcription start site (TSS) region of approximately 40% of yeast core promoters and the frequency of specific core promoter types appears to be conserved in yeast and human genomes. Gene Ontology analyses reveal that TATA-less genes in humans, as in yeast, are frequently involved in basic "housekeeping" processes, while TATA-containing genes are more often highly regulated, such as by biotic or stress stimuli. These results reveal unexpected similarities in the occurrence of specific core promoter types and in their associated biological processes in yeast and humans and point to novel vertebrate-specific DNA motifs that might play a selective role in TATA-independent transcription.
Collapse
Affiliation(s)
- Chuhu Yang
- Genetics Genomics and Bioinformatics Graduate Program, University of California, Riverside, CA 92521, USA
| | | | | | | | | |
Collapse
|
34
|
Morohashi N, Yamamoto Y, Kuwana S, Morita W, Shindo H, Mitchell AP, Shimizu M. Effect of sequence-directed nucleosome disruption on cell-type-specific repression by alpha2/Mcm1 in the yeast genome. EUKARYOTIC CELL 2006; 5:1925-33. [PMID: 16980406 PMCID: PMC1694797 DOI: 10.1128/ec.00105-06] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In Saccharomyces cerevisiae, a-cell-specific genes are repressed in MATalpha cells by alpha2/Mcm1, acting in concert with the Ssn6-Tup1 corepressors and the Isw2 chromatin remodeling complex, and nucleosome positioning has been proposed as one mechanism of repression. However, prior studies showed that nucleosome positioning is not essential for repression by alpha2/Mcm1 in artificial reporter plasmids, and the importance of the nucleosome positioning remains questionable. We have tested the function of positioned nucleosomes through alteration of genomic chromatin at the a-cell-specific gene BAR1. We report here that a positioned nucleosome in the BAR1 promoter is disrupted in cis by the insertion of diverse DNA sequences such as poly(dA) . poly(dT) and poly(dC-dG) . poly(dC-dG), leading to inappropriate partial derepression of BAR1. Also, we show that isw2 mutation causes loss of nucleosome positioning in BAR1 in MATalpha cells as well as partial disruption of repression. Thus, nucleosome positioning is required for full repression, but loss of nucleosome positioning is not sufficient to relieve repression completely. Even though disruption of nucleosome positioning by the cis- and trans-acting modulators of chromatin has a modest effect on the level of transcription, it causes significant degradation of the alpha-mating pheromone in MATalpha cells, thereby affecting its cell type identity. Our results illustrate a useful paradigm for analysis of chromatin structural effects at genomic loci.
Collapse
Affiliation(s)
- Nobuyuki Morohashi
- Department of Chemistry, Meisei University, 2-1-1 Hodokubo, Hino, Tokyo 191-8506, Japan
| | | | | | | | | | | | | |
Collapse
|
35
|
Zhang H, Yu H, Ren J, Qu X. Reversible B/Z-DNA transition under the low salt condition and non-B-form polydApolydT selectivity by a cubane-like europium-L-aspartic acid complex. Biophys J 2006; 90:3203-7. [PMID: 16473901 PMCID: PMC1432110 DOI: 10.1529/biophysj.105.078402] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2005] [Accepted: 01/10/2006] [Indexed: 11/18/2022] Open
Abstract
We report here that a cubane-like europium-L-aspartic acid complex at physiological pH can discriminate between DNA structures as judged by the comparison of thermal denaturation, binding stoichiometry, temperature-dependent fluorescence enhancement, and circular dichroism and gel electrophoresis studies. This complex can selectively stabilize non-B-form DNA polydApolydT but destabilize polydGdCpolydGdC and polydAdTpolydAdT. Further studies show that this complex can convert B-form polydGdCpolydGdC to Z-form under the low salt condition at physiological temperature 37 degrees C, and the transition is reversible, similar to RNA polymerase, which turns unwound DNA into Z-DNA and converts it back to B-DNA after transcription. The potential uses of a left-handed helix-selective probe in biology are obvious. Z-DNA is a transient structure and does not exist as a stable feature of the double helix. Therefore, probing this transient structure with a metal-amino acid complex under the low salt condition at physiological temperature would provide insights into their transitions in vivo and are of great interest.
Collapse
Affiliation(s)
- Haiyuan Zhang
- Division of Biological Inorganic Chemistry, Key Laboratory of Rare Earth Chemistry and Physics, Changchun Institute of Applied Chemistry, Graduate School of the Chinese Academy of Sciences, Changchun, Jilin 130022, China
| | | | | | | |
Collapse
|
36
|
Marx KA, Zhou Y, Kishawi IQ. Evidence for long poly(dA).poly(dT) tracts in D. discoideum DNA at high frequencies and their preferential avoidance of nucleosomal DNA core regions. J Biomol Struct Dyn 2006; 23:429-46. [PMID: 16363878 DOI: 10.1080/07391102.2006.10531237] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
The eukaryote, Dictyostelium discoideum, has one of the most (A+T) rich genomes studied to date. Isolated nuclear D. discoideum DNA (AX3 strain) was used to qualitatively determine the frequency and length distribution of long (dA).(dT) homopolymer tracts in this genome, in comparison to the less (A+T) rich calf thymus and Schistosoma mansoni DNAs that had few observable long tracts. These experimental data accurately reflect the significantly elevated frequencies of long tracts found computationally within the D. discoideum intron and flanking sequences, but not exons. PCR amplification of long (dA).(dT) homopolymer tract containing sequences was carried out. Then experimental biotinylated (dT)18 probe hybridization to the PCR amplified DNA showed that the long (dA).(dT) homopolymer tracts were enriched in D. discoideum sequences only hundreds of base pair in length, under conditions where no equivalent hybridization was observed to S. mansoni DNA or calf DNA sequences. Similar probe hybridization to DNA isolated following micrococcal nuclease digestion of D. discoideum chromatin demonstrated that long (dA).(dT) homopolymer tracts were more highly enriched in nucleosomal DNA lengths that included the internucleosomal linker as compared to shorter linker free mononucleosomal lengths. This observation is in agreement with the frequency of tract spacing results calculated from GenBank sequence data. These frequency data indicate that adjacent long tracts plus the intervening spacer DNA are found at peak lengths (average 42 bp), exactly characteristic of the internucleosomal spacer region of D. discoideum chromatin and are in sufficient number to be found in nearly half of all nucleosomes. Compared to shuffled tract sequence controls, these lengths of adjacent long tracts plus the intervening spacer DNA were found to be significantly enriched. Lesser enrichments are observed at lengths corresponding to adjacent tracts being separated by nucleosomal core length DNA sequences (145-185 bp). These data strongly suggest that adjacent long tracts occur spaced at selected lengths so as to avoid the central core regions of nucleosomes and instead are found localized within internucleosomal DNA linker and core edge regions in D. discoideum chromatin.
Collapse
Affiliation(s)
- Kenneth A Marx
- Center for Intelligent Biomaterials, Department of Chemistry, University of Massachusetts, Lowell, MA 01854, USA.
| | | | | |
Collapse
|
37
|
Adair JE, Kwon Y, Dement GA, Smerdon MJ, Reeves R. Inhibition of nucleotide excision repair by high mobility group protein HMGA1. J Biol Chem 2005; 280:32184-92. [PMID: 16033759 DOI: 10.1074/jbc.m505600200] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The mammalian non-histone "high mobility group" A (HMGA) proteins are the primary nuclear proteins that bind to the minor groove of AT-rich DNA. They may, therefore, influence the formation and/or repair of DNA lesions that occur in AT-rich DNA, such as cyclobutane pyrimidine dimers (CPDs) induced by UV radiation. Employing both stably transfected lines of human MCF7 cells containing tetracycline-regulated HMGA1 transgenes and primary Hs578T tumor cells, which naturally overexpress HMGA1 proteins, we have shown that cells overexpressing HMGA1a protein exhibit increased UV sensitivity. Moreover, we demonstrated that knockdown of intracellular HMGA1 concentrations via two independent methods abrogated this sensitivity. Most significantly, we observed that HMGA1a overexpression inhibited global genomic nucleotide excision repair of UV-induced CPD lesions in MCF-7 cells. Consistent with these findings in intact cells, DNA repair experiments employing Xenopus oocyte nuclear extracts and lesion-containing DNA substrates demonstrated that binding of HMGA1a markedly inhibits removal of CPDs in vitro. Furthermore, UV "photo-foot-printing" demonstrated that CPD formation within a long run of Ts (T(18)-tract) in a DNA substrate changes significantly when HMGA1 is bound prior to UV irradiation. Together, these results suggest that HMGA1 directly influences both the formation and repair of UV-induced DNA lesions in intact cells. These findings have important implications for the role that HMGA protein overexpression might play in the accumulation of mutations and genomic instabilities associated with many types of human cancers.
Collapse
Affiliation(s)
- Jennifer E Adair
- School of Molecular Biosciences, Biochemistry, and Biophysics, Washingston State University, Pullman, 99164-4660, USA
| | | | | | | | | |
Collapse
|
38
|
Homopolymer tract length dependent enrichments in functional regions of 27 eukaryotes and their novel dependence on the organism DNA (G+C)% composition. BMC Genomics 2004; 5:95. [PMID: 15598342 PMCID: PMC539357 DOI: 10.1186/1471-2164-5-95] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2004] [Accepted: 12/14/2004] [Indexed: 12/16/2022] Open
Abstract
Background DNA homopolymer tracts, poly(dA).poly(dT) and poly(dG).poly(dC), are the simplest of simple sequence repeats. Homopolymer tracts have been systematically examined in the coding, intron and flanking regions of a limited number of eukaryotes. As the number of DNA sequences publicly available increases, the representation (over and under) of homopolymer tracts of different lengths in these regions of different genomes can be compared. Results We carried out a survey of the extent of homopolymer tract over-representation (enrichment) and over-proportional length distribution (above expected length) primarily in the single gene documents, but including some whole chromosomes of 27 eukaryotics across the (G+C)% composition range from 20 – 60%. A total of 5.2 × 107 bases from 15,560 cleaned (redundancy removed) sequence documents were analyzed. Calculated frequencies of non-overlapping long homopolymer tracts were found over-represented in non-coding sequences of eukaryotes. Long poly(dA).poly(dT) tracts demonstrated an exponential increase with tract length compared to predicted frequencies. A novel negative slope was observed for all eukaryotes between their (G+C)% composition and the threshold length N where poly(dA).poly(dT) tracts exhibited over-representation and a corresponding positive slope was observed for poly(dG).poly(dC) tracts. Tract size thresholds where over-representation of tracts in different eukaryotes began to occur was between 4 – 11 bp depending upon the organism (G+C)% composition. The higher the GC%, the lower the threshold N value was for poly(dA).poly(dT) tracts, meaning that the over-representation happens at relatively lower tract length in more GC-rich surrounding sequence. We also observed a novel relationship between the highest over-representations, as well as lengths of homopolymer tracts in excess of their random occurrence expected maximum lengths. Conclusions We discuss how our novel tract over-representation observations can be accounted for by a few models. A likely model for poly(dA).poly(dT) tract over-representation involves the known insertion into genomes of DNA synthesized from retroviral mRNAs containing 3' polyA tails. A proposed model that can account for a number of our observed results, concerns the origin of the isochore nature of eukaryotic genomes via a non-equilibrium GC% dependent mutation rate mechanism. Our data also suggest that tract lengthening via slip strand replication is not governed by a simple thermodynamic loop energy model.
Collapse
|
39
|
Davey CS, Pennings S, Reilly C, Meehan RR, Allan J. A determining influence for CpG dinucleotides on nucleosome positioning in vitro. Nucleic Acids Res 2004; 32:4322-31. [PMID: 15310836 PMCID: PMC514372 DOI: 10.1093/nar/gkh749] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
DNA sequence information that directs the translational positioning of nucleosomes can be attenuated by cytosine methylation when a short run of CpG dinucleotides is located close to the dyad axis of the nucleosome. Here, we show that point mutations introduced to re-pattern methylation at the (CpG)3 element in the chicken betaA-globin promoter sequence themselves strongly influenced nucleosome formation in reconstituted chromatin. The disruptive effect of cytosine methylation on nucleosome formation was found to be determined by the sequence context of CpG dinucleotides, not just their location in the positioning sequence. Additional mutations indicated that methylation can also promote the occupation of certain nucleosome positions. DNase I analysis demonstrated that these genetic and epigenetic modifications altered the structural characteristics of the (CpG)3 element. Our findings support a proposal that the intrinsic structural properties of the DNA at the -1.5 site, as occupied by (CpG)3 in the nucleosome studied, can be decisive for nucleosome formation and stability, and that changes in anisotropic DNA bending or flexibility at this site explain why nucleosome positioning can be exquisitely sensitive to genetic and epigenetic modification of the DNA sequence.
Collapse
Affiliation(s)
- Colin S Davey
- Institute of Cell and Molecular Biology, University of Edinburgh, Darwin Building, King's Buildings, West Mains Road, Edinburgh EH9 3JR, UK
| | | | | | | | | |
Collapse
|
40
|
Breier AM, Chatterji S, Cozzarelli NR. Prediction of Saccharomyces cerevisiae replication origins. Genome Biol 2004; 5:R22. [PMID: 15059255 PMCID: PMC395781 DOI: 10.1186/gb-2004-5-4-r22] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2003] [Revised: 02/02/2004] [Accepted: 02/04/2004] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND Autonomously replicating sequences (ARSs) function as replication origins in Saccharomyces cerevisiae. ARSs contain the 17 bp ARS consensus sequence (ACS), which binds the origin recognition complex. The yeast genome contains more than 10,000 ACS matches, but there are only a few hundred origins, and little flanking sequence similarity has been found. Thus, identification of origins by sequence alone has not been possible. RESULTS We developed an algorithm, Oriscan, to predict yeast origins using similarity to 26 characterized origins. Oriscan used 268 bp of sequence, including the T-rich ACS and a 3' A-rich region. The predictions identified the exact location of the ACS. A total of 84 of the top 100 Oriscan predictions, and 56% of the top 350, matched known ARSs or replication protein binding sites. The true accuracy was even higher because we tested 25 discrepancies, and 15 were in fact ARSs. Thus, 94% of the top 100 predictions and an estimated 70% of the top 350 were correct. We compared the predictions to corresponding sequences in related Saccharomyces species and found that the ACSs of experimentally supported predictions show significant conservation. CONCLUSIONS The high accuracy of the predictions indicates that we have defined near-sufficient conditions for ARS activity, the A-rich region is a recognizable feature of ARS elements with a probable role in replication initiation, and nucleotide sequence is a reliable predictor of yeast origins. Oriscan detected most origins in the genome, demonstrating previously unrecognized generality in yeast replication origins and significant discriminatory power in the algorithm.
Collapse
Affiliation(s)
- Adam M Breier
- Graduate Group in Biophysics, University of California-Berkeley, Berkeley, CA 94720-3204, USA
| | - Sourav Chatterji
- Department of Computer Science, University of California-Berkeley, Berkeley, CA 94720-3204, USA
| | - Nicholas R Cozzarelli
- Department of Molecular and Cellular Biology, Barker Hall, University of California-Berkeley, Berkeley, CA 94720-3204, USA
| |
Collapse
|
41
|
Cleary JD, Pearson CE. The contribution of cis-elements to disease-associated repeat instability: clinical and experimental evidence. Cytogenet Genome Res 2003; 100:25-55. [PMID: 14526163 DOI: 10.1159/000072837] [Citation(s) in RCA: 116] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2002] [Accepted: 02/11/2003] [Indexed: 11/19/2022] Open
Abstract
Alterations in the length (instability) of gene-specific microsatellites and minisatellites are associated with at least 35 human diseases. This review will discuss the various cis-elements that contribute to repeat instability, primarily through examination of the most abundant disease-associated repetitive element, trinucleotide repeats. For the purpose of this review, we define cis-elements to include the sequence of the repeat units, the length and purity of the repeat tracts, the sequences flanking the repeat, as well as the surrounding epigenetic environment, including DNA methylation and chromatin structure. Gender-, tissue-, developmental- and locus-specific cis-elements in conjunction with trans-factors may facilitate instability through the processes of DNA replication, repair and/or recombination. Here we review the available human data that supports the involvement of cis-elements in repeat instability with limited reference to model systems. In diverse tissues at different developmental times and at specific loci, repetitive elements display variable levels of instability, suggesting vastly different mechanisms may be responsible for repeat instability amongst the disease loci and between various tissues.
Collapse
Affiliation(s)
- J D Cleary
- Program of Genetics and Genomic Biology, The Hospital for Sick Children, and Department of Molecular and Medical Genetics, University of Toronto, Toronto, Ontario, Canada
| | | |
Collapse
|
42
|
Belli SI, Monnerat S, Schaff C, Masina S, Noll T, Myler PJ, Stuart K, Fasel N. Sense and antisense transcripts in the histone H1 (HIS-1) locus of Leishmania major. Int J Parasitol 2003; 33:965-75. [PMID: 12906880 DOI: 10.1016/s0020-7519(03)00126-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Histone H1 in the parasitic protozoan Leishmania is a developmentally regulated protein encoded by two genes, HIS-1.1 and HIS-1.2. These genes are separated by approximately 20 kb of sequence and are located on the same DNA strand of chromosome 27. When Northern blots of parasite RNA were probed with HIS-1 strand-specific riboprobes, we detected sense and antisense transcripts that were polyadenylated and developmentally regulated. When the HIS-1.2 coding region was replaced with the coding region of the neomycin phosphotransferase gene, antisense transcription of this gene was unaffected, indicating that the regulatory elements controlling antisense transcription were located outside of the HIS-1.2 gene, and that transcription in Leishmania can occur from both DNA strands even in the presence of transcription of a selectable marker in the complementary strand. A search for other antisense transcripts within the HIS-1 locus identified an additional transcript (SC-1) within the intervening HIS-1 sequence, downstream of adenine and thymine-rich sequences. These results show that gene expression in Leishmania is not only regulated polycistronically from the sense strand of genomic DNA, but that the complementary strand of DNA also contains sequences that could drive expression of open reading frames from the antisense strand of DNA. These findings suggest that the parasite has evolved in such a way as to maximise the transcription of its genome, a mechanism that might be important for it to maintain virulence.
Collapse
Affiliation(s)
- Sabina I Belli
- Institute of Biochemistry, University of Lausanne, Ch. des Boveresses 155, Epalinges, 1066, Switzerland
| | | | | | | | | | | | | | | |
Collapse
|
43
|
Shimizu M, Mitchell AP. Hap1p photofootprinting as an in vivo assay of repression mechanism in Saccharomyces cerevisiae. Methods Enzymol 2003; 370:479-87. [PMID: 14712669 DOI: 10.1016/s0076-6879(03)70041-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
|
44
|
Azam M, Kesarwani M, Chakraborty S, Natarajan K, Datta A. Cloning and characterization of the 5'-flanking region of the oxalate decarboxylase gene from Flammulina velutipes. Biochem J 2002; 367:67-75. [PMID: 12020349 PMCID: PMC1222848 DOI: 10.1042/bj20011573] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2001] [Revised: 03/25/2002] [Accepted: 05/21/2002] [Indexed: 11/17/2022]
Abstract
The oxalate-degrading enzyme, oxalate decarboxylase (OXDC), was purified and characterized from Flammulina velutipes, a basidiomycetous fungus [Mehta and Datta (1991) J. Biol. Chem. 266, 23548-23553]. The cDNA cloning and analyses revealed that OXDC transcription was induced by oxalic acid. However, in this report, we show that OXDC transcription is induced by low pH, not by oxalate. To understand the regulatory mechanism of OXDC expression, we have cloned and analysed a 580-bp genomic fragment from the 5'-flanking region of the OXDC gene. Sequence analysis showed the presence of several eukaryotic transcription factor binding motifs within the -580 bp of the upstream region. Electrophoretic-mobility-shift assays with partially purified cell extracts revealed specific binding of a factor in acid-induced, but not in uninduced, extracts. Furthermore, DNase I protection assays using the partially purified fraction from oxalic acid-induced extract revealed a footprint of a 13-bp sequence 5'GCGGGGTCGCCGA3', termed low pH responsive element (LPRE), corresponding to the -287 to -275 bp region of the OXDC promoter. Our results suggest that in F. velutipes cells, activation of OXDC transcription in response to low pH is mediated by the binding of a novel transcription factor through the LPRE site in the OXDC promoter.
Collapse
Affiliation(s)
- Mohammad Azam
- Molecular Biology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi - 110067, India
| | | | | | | | | |
Collapse
|
45
|
Warmlander S, Sponer JE, Sponer J, Leijon M. The influence of the thymine C5 methyl group on spontaneous base pair breathing in DNA. J Biol Chem 2002; 277:28491-7. [PMID: 12029089 DOI: 10.1074/jbc.m202989200] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Sequences of four or more AT base pairs without a 5'-TA-3' step, so-called A-tracts, influence the global properties of DNA by causing curvature of the helix axis if phased with the helical repeat and also influence nucleosome packaging. Hence it is interesting to understand this phenomenon on the molecular level, and numerous studies have been devoted to investigations of dynamical and structural features of A-tract DNA. It was early observed that anomalously slow base pair-opening kinetics were a striking physical property unique to DNA A-tracts (Leroy, J. L., Charretier, E., Kochoyan, M., and Gueron, M. (1988) Biochemistry 27, 8894-8898). Furthermore, a strong correlation between DNA curvature and anomalously slow base pair-opening dynamics was found. In the present work it is shown, using imino proton exchange measurements by NMR spectroscopy that the main contribution to the dampening of the base pair-opening fluctuations in A-tracts comes from the C5 methylation of the thymine base. Because the methyl group has been shown to have a very limited effect on the DNA curvature as well as the structure of the DNA helix, the thymine C5 methyl group stabilizes the helix directly. Empirical potential energy calculations show that methylation of the tract improves the stacking energy of a base pair with its neighbors in the tract by 3-4 kcal/mol.
Collapse
Affiliation(s)
- Sebastian Warmlander
- Department of Biochemistry and Biophysics, Arrhenius Laboratory, Stockholm University, S-106 91 Stockholm, Sweden
| | | | | | | |
Collapse
|
46
|
Yoshimura A, Ura K, Asakura H, Kominami R, Mishima Y. Mononucleosomes assembled on a DNA fragment containing (GGA/TCC)(n) repeats can form a DNA-DNA complex. Biochem Biophys Res Commun 2002; 290:16-22. [PMID: 11779126 DOI: 10.1006/bbrc.2001.6135] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A DNA fragment of 163 bp containing 11 GGA repeats formed two-end positioned mononucleosomes as efficiently as that of CTG repeats. However, the rotational positioning of the GGA fragment was weak because clear DNase I cleavage patterns with 10-base periodicity were not seen near the center of the GGA fragment but were detected in the entire region of the CTG fragment. Incubation of the GGA mononucleosomes with the same fragment provided the DNA-DNA complex, which had been shown by using naked DNA fragments. DNase I digestion of the complex exhibited protection in the GGA repeats and in flanking sequences of about 30 bp at both sides, suggesting that both the repeat and flanking regions were involved in the association. Interestingly, histone H1, which enhanced DNA-DNA association on naked DNA, did not affect the complex formation on mononucleosomes. These results imply that GGA microsatellites in genomes could associate with one another at multiple sites and that the association may play a role in functional organization of higher order chromatin architecture.
Collapse
Affiliation(s)
- Akira Yoshimura
- Division of Molecular Biology, Department of Gene Regulation, Niigata University Graduate School of Medical and Dental Sciences, Niigata 951-8510, Japan
| | | | | | | | | |
Collapse
|
47
|
Duhagon MA, Dallagiovanna B, Garat B. Unusual features of poly[dT-dG].[dC-dA] stretches in CDS-flanking regions of Trypanosoma cruzi genome. Biochem Biophys Res Commun 2001; 287:98-103. [PMID: 11549259 DOI: 10.1006/bbrc.2001.5545] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In trypanosomatids, the mechanisms of gene expression regulation are not yet well understood. The genes are organized into long polycistronic transcription units separated by intergenic regions that may contain the signaling information for nucleic acid processing. Poly-dinucleotides are frequent in these regions and have been proposed to be involved in gene expression regulation. We analyzed their frequency in CDS-flanking sequences of sense strands in Trypanosoma cruzi and established that all but poly[dC-dC], poly[dC-dG], and poly[dG-dG] are significantly more frequent than expected by chance. Poly[dT-dG].[dC-dA] is among the longest and most frequent poly-dinucleotides and shows a remarkable strand asymmetry. Furthermore, electrophoretic mobility shift assays using T. cruzi epimastigotes nuclear extracts demonstrated the existence of at least, one sequence specific single-strand binding activity for each strand. These results strongly suggest that poly[dT-dG].[dC-dA] sequence is involved in regulatory mechanisms of relevance for the parasite biology.
Collapse
Affiliation(s)
- M A Duhagon
- Sección Bioquímica, Departamento de Biología Celular y Molecular, Facultad de Ciencias, Universidad de la República, Iguá 4225, 11400 Montevideo, Uruguay
| | | | | |
Collapse
|
48
|
Anderson JD, Widom J. Poly(dA-dT) promoter elements increase the equilibrium accessibility of nucleosomal DNA target sites. Mol Cell Biol 2001; 21:3830-9. [PMID: 11340174 PMCID: PMC87046 DOI: 10.1128/mcb.21.11.3830-3839.2001] [Citation(s) in RCA: 129] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Polypurine tracts are important elements of eukaryotic promoters. They are believed to somehow destabilize chromatin, but the mechanism of their action is not known. We show that incorporating an A(16) element at an end of the nucleosomal DNA and further inward destabilizes histone-DNA interactions by 0.1 +/- 0.03 and 0.35 +/- 0.04 kcal mol(-1), respectively, and is accompanied by 1.5- +/- 0.1-fold and 1.7- +/- 0.1-fold increases in position-averaged equilibrium accessibility of nucleosomal DNA target sites. These effects are comparable in magnitude to effects of A(16) elements that correlate with transcription in vivo, suggesting that our system may capture most of their physiological role. These results point to two distinct but interrelated models for the mechanism of action of polypurine tract promoter elements in vivo. Given a nucleosome positioned over a promoter region, the presence of a polypurine tract in that nucleosome's DNA decreases the stability of the DNA wrapping, increasing the equilibrium accessibility of other DNA target sites buried inside that nucleosome. Alternatively (if nucleosomes are freely mobile), the presence of a polypurine tract provides a free energy bias for the nucleosome to move to alternative locations, thereby changing the equilibrium accessibilities of other nearby DNA target sites.
Collapse
Affiliation(s)
- J D Anderson
- Department of Biochemistry, Molecular Biology, and Cell Biology, Illinois 60208, USA
| | | |
Collapse
|
49
|
Havas K, Flaus A, Phelan M, Kingston R, Wade PA, Lilley DM, Owen-Hughes T. Generation of superhelical torsion by ATP-dependent chromatin remodeling activities. Cell 2000; 103:1133-42. [PMID: 11163188 DOI: 10.1016/s0092-8674(00)00215-4] [Citation(s) in RCA: 222] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
ATP-dependent chromatin remodeling activities participate in the alteration of chromatin structure during gene regulation. All have DNA- or chromatin-stimulated ATPase activity and many can alter the structure of chromatin; however, the means by which they do this have remained unclear. Here we describe a novel activity for ATP-dependent chromatin remodeling activities, the ability to generate unconstrained negative superhelical torsion in DNA and chromatin. We find that the ability to distort DNA is shared by the yeast SWI/SNF complex, Xenopus Mi-2 complex, recombinant ISWI, and recombinant BRG1, suggesting that the generation of superhelical torsion represents a primary biomechanical activity shared by all Snf2p-related ATPase motors. The generation of superhelical torque provides a potent means by which ATP-dependent chromatin remodeling activities can manipulate chromatin structure.
Collapse
Affiliation(s)
- K Havas
- Division of Gene Regulation, The Wellcome Trust Biocentre, Dundee DD1 5EH, Scotland, United Kingdom
| | | | | | | | | | | | | |
Collapse
|
50
|
Suter B, Schnappauf G, Thoma F. Poly(dA.dT) sequences exist as rigid DNA structures in nucleosome-free yeast promoters in vivo. Nucleic Acids Res 2000; 28:4083-9. [PMID: 11058103 PMCID: PMC113125 DOI: 10.1093/nar/28.21.4083] [Citation(s) in RCA: 114] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Poly(dA.dT) sequences (T-tracts) are abundant genomic DNA elements with unusual properties in vitro and an established role in transcriptional regulation of yeast genes. In vitro T-tracts are rigid, contribute to DNA bending, affect assembly in nucleosomes and generate a characteristic pattern of CPDs (cyclobutane pyrimidine dimers) upon irradiation with UV light (UV photofootprint). In eukaryotic cells, where DNA is packaged in chromatin, the DNA structure of T-tracts is unknown. Here we have used in vivo UV photofootprinting and DNA repair by photolyase to investigate the structure and accessibility of T-tracts in yeast promoters (HIS3, URA3 and ILV1). The same characteristic photofootprints were obtained in yeast and in naked DNA, demonstrating that the unusual T-tract structure exists in living cells. Rapid repair of CPDs in the T-tracts demonstrates that these T-tracts were not folded in nucleosomes. Moreover, neither datin, a T-tract binding protein, nor Gcn5p, a histone acetyltransferase involved in nucleosome remodelling, showed an influence on the structure and accessibility of T-tracts. The data support a contribution of this unusual DNA structure to transcriptional regulation.
Collapse
MESH Headings
- Acetyltransferases/genetics
- Acetyltransferases/metabolism
- Base Sequence
- Chromosomes, Fungal/chemistry
- Chromosomes, Fungal/genetics
- Chromosomes, Fungal/metabolism
- Chromosomes, Fungal/radiation effects
- DNA Damage/genetics
- DNA Damage/radiation effects
- DNA Footprinting
- DNA Repair/genetics
- DNA, Fungal/chemistry
- DNA, Fungal/genetics
- DNA, Fungal/metabolism
- DNA, Fungal/radiation effects
- DNA-Binding Proteins/genetics
- DNA-Binding Proteins/metabolism
- Deoxyribodipyrimidine Photo-Lyase/metabolism
- Dopamine Plasma Membrane Transport Proteins
- Fungal Proteins/genetics
- Fungal Proteins/metabolism
- Gene Expression Regulation, Fungal
- Genes, Fungal/genetics
- Genome, Fungal
- Histone Acetyltransferases
- Hydro-Lyases/genetics
- Membrane Glycoproteins
- Membrane Transport Proteins
- Nerve Tissue Proteins
- Nucleic Acid Conformation
- Nucleosomes/physiology
- Pliability
- Poly A/genetics
- Poly T/genetics
- Promoter Regions, Genetic/genetics
- Protein Kinases/genetics
- Protein Kinases/metabolism
- Saccharomyces cerevisiae Proteins
- Ultraviolet Rays
- Yeasts/enzymology
- Yeasts/genetics
- Yeasts/radiation effects
Collapse
Affiliation(s)
- B Suter
- Institut für Zellbiologie, ETH-Zürich, Hönggerberg, CH-8093 Zürich, Switzerland
| | | | | |
Collapse
|