1
|
Wang J, Weatheritt R, Voineagu I. Alu-minating the Mechanisms Underlying Primate Cortex Evolution. Biol Psychiatry 2022; 92:760-771. [PMID: 35981906 DOI: 10.1016/j.biopsych.2022.04.021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Revised: 04/04/2022] [Accepted: 04/28/2022] [Indexed: 11/02/2022]
Abstract
The higher-order cognitive functions observed in primates correlate with the evolutionary enhancement of cortical volume and folding, which in turn are driven by the primate-specific expansion of cellular diversity in the developing cortex. Underlying these changes is the diversification of molecular features including the creation of human and/or primate-specific genes, the activation of specific molecular pathways, and the interplay of diverse layers of gene regulation. We review and discuss evidence for connections between Alu elements and primate brain evolution, the evolutionary milestones of which are known to coincide along primate lineages. Alus are repetitive elements that contribute extensively to the acquisition of novel genes and the expansion of diverse gene regulatory layers, including enhancers, alternative splicing, RNA editing, and microRNA pathways. By reviewing the impact of Alus on molecular features linked to cortical expansions or gyrification or implications in cognitive deficits, we suggest that future research focusing on the role of Alu-derived molecular events in the context of brain development may greatly advance our understanding of higher-order cognitive functions and neurologic disorders.
Collapse
Affiliation(s)
- Juli Wang
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, Australia.
| | - Robert Weatheritt
- St Vincent Clinical School, University of New South Wales, Sydney, Australia; Garvan Institute of Medical Research, EMBL Australia, Sydney, New South Wales, Australia
| | - Irina Voineagu
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, Australia; Cellular Genomics Futures Institute, University of New South Wales, Sydney, Australia.
| |
Collapse
|
2
|
The Mutagenic Consequences of DNA Methylation within and across Generations. EPIGENOMES 2022; 6:epigenomes6040033. [PMID: 36278679 PMCID: PMC9624357 DOI: 10.3390/epigenomes6040033] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2022] [Revised: 09/20/2022] [Accepted: 09/28/2022] [Indexed: 12/28/2022] Open
Abstract
DNA methylation is an epigenetic modification with wide-ranging consequences across the life of an organism. This modification can be stable, persisting through development despite changing environmental conditions. However, in other contexts, DNA methylation can also be flexible, underlying organismal phenotypic plasticity. One underappreciated aspect of DNA methylation is that it is a potent mutagen; methylated cytosines mutate at a much faster rate than other genetic motifs. This mutagenic property of DNA methylation has been largely ignored in eco-evolutionary literature, despite its prevalence. Here, we explore how DNA methylation induced by environmental and other factors could promote mutation and lead to evolutionary change at a more rapid rate and in a more directed manner than through stochastic genetic mutations alone. We argue for future research on the evolutionary implications of DNA methylation driven mutations both within the lifetime of organisms, as well as across timescales.
Collapse
|
3
|
Judd J, Sanderson H, Feschotte C. Evolution of mouse circadian enhancers from transposable elements. Genome Biol 2021; 22:193. [PMID: 34187518 PMCID: PMC8240256 DOI: 10.1186/s13059-021-02409-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Accepted: 06/10/2021] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Transposable elements are increasingly recognized as a source of cis-regulatory variation. Previous studies have revealed that transposons are often bound by transcription factors and some have been co-opted into functional enhancers regulating host gene expression. However, the process by which transposons mature into complex regulatory elements, like enhancers, remains poorly understood. To investigate this process, we examined the contribution of transposons to the cis-regulatory network controlling circadian gene expression in the mouse liver, a well-characterized network serving an important physiological function. RESULTS ChIP-seq analyses reveal that transposons and other repeats contribute ~ 14% of the binding sites for core circadian regulators (CRs) including BMAL1, CLOCK, PER1/2, and CRY1/2, in the mouse liver. RSINE1, an abundant murine-specific SINE, is the only transposon family enriched for CR binding sites across all datasets. Sequence analyses and reporter assays reveal that the circadian regulatory activity of RSINE1 stems from the presence of imperfect CR binding motifs in the ancestral RSINE1 sequence. These motifs matured into canonical motifs through point mutations after transposition. Furthermore, maturation occurred preferentially within elements inserted in the proximity of ancestral CR binding sites. RSINE1 also acquired motifs that recruit nuclear receptors known to cooperate with CRs to regulate circadian gene expression specifically in the liver. CONCLUSIONS Our results suggest that the birth of enhancers from transposons is predicated both by the sequence of the transposon and by the cis-regulatory landscape surrounding their genomic integration site.
Collapse
Affiliation(s)
- Julius Judd
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, 14853, USA
| | - Hayley Sanderson
- Department of Human Genetics, University of Utah School of Medicine, Salt Lake City, UT, 84112, USA
| | - Cédric Feschotte
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, 14853, USA.
| |
Collapse
|
4
|
Zhang XO, Pratt H, Weng Z. Investigating the Potential Roles of SINEs in the Human Genome. Annu Rev Genomics Hum Genet 2021; 22:199-218. [PMID: 33792357 DOI: 10.1146/annurev-genom-111620-100736] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Short interspersed nuclear elements (SINEs) are nonautonomous retrotransposons that occupy approximately 13% of the human genome. They are transcribed by RNA polymerase III and can be retrotranscribed and inserted back into the genome with the help of other autonomous retroelements. Because they are preferentially located close to or within gene-rich regions, they can regulate gene expression by various mechanisms that act at both the DNA and the RNA levels. In this review, we summarize recent findings on the involvement of SINEs in different types of gene regulation and discuss the potential regulatory functions of SINEs that are in close proximity to genes, Pol III-transcribed SINE RNAs, and embedded SINE sequences within Pol II-transcribed genes in the human genome. These discoveries illustrate how the human genome has exapted some SINEs into functional regulatory elements.
Collapse
Affiliation(s)
- Xiao-Ou Zhang
- Program in Bioinformatics and Integrative Biology, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA; .,Current affiliation: School of Life Sciences and Technology, Tongji University, Shanghai 200092, China
| | - Henry Pratt
- Program in Bioinformatics and Integrative Biology, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA;
| | - Zhiping Weng
- Program in Bioinformatics and Integrative Biology, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA;
| |
Collapse
|
5
|
Tiwari B, Jones AE, Caillet CJ, Das S, Royer SK, Abrams JM. p53 directly represses human LINE1 transposons. Genes Dev 2020; 34:1439-1451. [PMID: 33060137 PMCID: PMC7608743 DOI: 10.1101/gad.343186.120] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Accepted: 09/14/2020] [Indexed: 12/16/2022]
Abstract
p53 is a potent tumor suppressor and commonly mutated in human cancers. Recently, we demonstrated that p53 genes act to restrict retrotransposons in germline tissues of flies and fish but whether this activity is conserved in somatic human cells is not known. Here we show that p53 constitutively restrains human LINE1s by cooperatively engaging sites in the 5'UTR and stimulating local deposition of repressive histone marks at these transposons. Consistent with this, the elimination of p53 or the removal of corresponding binding sites in LINE1s, prompted these retroelements to become hyperactive. Concurrently, p53 loss instigated chromosomal rearrangements linked to LINE sequences and also provoked inflammatory programs that were dependent on reverse transcriptase produced from LINE1s. Taken together, our observations establish that p53 continuously operates at the LINE1 promoter to restrict autonomous copies of these mobile elements in human cells. Our results further suggest that constitutive restriction of these retroelements may help to explain tumor suppression encoded by p53, since erupting LINE1s produced acute oncogenic threats when p53 was absent.
Collapse
Affiliation(s)
- Bhavana Tiwari
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
| | - Amanda E Jones
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
| | - Candace J Caillet
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
| | - Simanti Das
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
| | - Stephanie K Royer
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
| | - John M Abrams
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
| |
Collapse
|
6
|
Sammons MA, Nguyen TAT, McDade SS, Fischer M. Tumor suppressor p53: from engaging DNA to target gene regulation. Nucleic Acids Res 2020; 48:8848-8869. [PMID: 32797160 PMCID: PMC7498329 DOI: 10.1093/nar/gkaa666] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2020] [Revised: 07/24/2020] [Accepted: 07/30/2020] [Indexed: 12/13/2022] Open
Abstract
The p53 transcription factor confers its potent tumor suppressor functions primarily through the regulation of a large network of target genes. The recent explosion of next generation sequencing protocols has enabled the study of the p53 gene regulatory network (GRN) and underlying mechanisms at an unprecedented depth and scale, helping us to understand precisely how p53 controls gene regulation. Here, we discuss our current understanding of where and how p53 binds to DNA and chromatin, its pioneer-like role, and how this affects gene regulation. We provide an overview of the p53 GRN and the direct and indirect mechanisms through which p53 affects gene regulation. In particular, we focus on delineating the ubiquitous and cell type-specific network of regulatory elements that p53 engages; reviewing our understanding of how, where, and when p53 binds to DNA and the mechanisms through which these events regulate transcription. Finally, we discuss the evolution of the p53 GRN and how recent work has revealed remarkable differences between vertebrates, which are of particular importance to cancer researchers using mouse models.
Collapse
Affiliation(s)
- Morgan A Sammons
- Department of Biological Sciences and The RNA Institute, University at Albany, State University of New York, 1400 Washington Avenue, Albany, NY 12222, USA
| | - Thuy-Ai T Nguyen
- Genome Integrity & Structural Biology Laboratory and Immunity, Inflammation and Disease Laboratory, National Institute of Environmental Health Sciences/National Institutes of Health, 111 TW Alexander Drive, Research Triangle Park, NC 27709, USA
| | - Simon S McDade
- Patrick G Johnston Centre for Cancer Research, Queen's University Belfast, 97 Lisburn Road, Belfast BT9 7AE, UK
| | - Martin Fischer
- Computational Biology Group, Leibniz Institute on Aging – Fritz Lipmann Institute (FLI), Beutenbergstraße 11, 07745 Jena, Germany
| |
Collapse
|
7
|
Hanson HE, Koussayer B, Kilvitis HJ, Schrey AW, Maddox JD, Martin LB. Epigenetic Potential in Native and Introduced Populations of House Sparrows (Passer domesticus). Integr Comp Biol 2020; 60:1458-1468. [PMID: 32497186 DOI: 10.1093/icb/icaa060] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Epigenetic potential, defined as the capacity for epigenetically-mediated phenotypic plasticity, may play an important role during range expansions. During range expansions, populations may encounter relatively novel challenges while experiencing lower genetic diversity. Phenotypic plasticity via epigenetic potential might be selectively advantageous at the time of initial introduction or during spread into new areas, enabling introduced organisms to cope rapidly with novel challenges. Here, we asked whether one form of epigenetic potential (i.e., the abundance of CpG sites) in three microbial surveillance genes: Toll-like receptors (TLRs) 1B (TLR1B), 2A (TLR2A), and 4 (TLR4) varied between native and introduced house sparrows (Passer domesticus). Using an opportunistic approach based on samples collected from sparrow populations around the world, we found that introduced birds had more CpG sites in TLR2A and TLR4, but not TLR1B, than native ones. Introduced birds also lost more CpG sites in TLR1B, gained more CpG sites in TLR2A, and lost fewer CpG sites in TLR4 compared to native birds. These results were not driven by differences in genetic diversity or population genetic structure, and many CpG sites fell within predicted transcription factor binding sites (TFBS), with losses and gains of CpG sites altering predicted TFBS. Although we lacked statistical power to conduct the most rigorous possible analyses, these results suggest that epigenetic potential may play a role in house sparrow range expansions, but additional work will be critical to elucidating how epigenetic potential affects gene expression and hence phenotypic plasticity at the individual, population, and species levels.
Collapse
Affiliation(s)
- Haley E Hanson
- Global and Planetary Health, University of South Florida, 3720 Spectrum Blvd, Suite 304, Tampa, FL 33620, USA
| | - Bilal Koussayer
- Global and Planetary Health, University of South Florida, 3720 Spectrum Blvd, Suite 304, Tampa, FL 33620, USA
| | - Holly J Kilvitis
- Department of Integrative Biology, University of South Florida, 4202 E. Fowler Ave, SCA110, Tampa, FL 33620, USA
| | - Aaron W Schrey
- Department of Biology, Georgia Southern University, Armstrong Campus, 11935 Abercorn St, SC1010, Savannah, GA 31419, USA
| | - J Dylan Maddox
- Field Museum of Natural History, 1400 S. Lake Shore Drive, Chicago, IL 60605, USA.,Laboratorio de Biotecnología y Bioenergética, Universidad Científica del Perú, Iquitos, Perú.,American Public University System, Environmental Sciences, Charles Town, WV 25414, USA
| | - Lynn B Martin
- Global and Planetary Health, University of South Florida, 3720 Spectrum Blvd, Suite 304, Tampa, FL 33620, USA
| |
Collapse
|
8
|
Cytosine Methylation Affects the Mutability of Neighboring Nucleotides in Germline and Soma. Genetics 2020; 214:809-823. [PMID: 32079595 DOI: 10.1534/genetics.120.303028] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Accepted: 02/12/2020] [Indexed: 02/07/2023] Open
Abstract
Methylated cytosines deaminate at higher rates than unmethylated cytosines, and the lesions they produce are repaired less efficiently. As a result, methylated cytosines are mutational hotspots. Here, combining rare polymorphism and base-resolution methylation data in humans, Arabidopsis thaliana, and rice (Oryza sativa), we present evidence that methylation state affects mutation dynamics not only at the focal cytosine but also at neighboring nucleotides. In humans, contrary to prior suggestions, we find that nucleotides in the close vicinity (±3 bp) of methylated cytosines mutate less frequently. Reduced mutability around methylated CpGs is also observed in cancer genomes, considering single nucleotide variants alongside tissue-of-origin-matched methylation data. In contrast, methylation is associated with increased neighborhood mutation risk in A. thaliana and rice. The difference in neighborhood mutation risk is less pronounced further away from the focal CpG and modulated by regional GC content. Our results are consistent with a model where altered risk at neighboring bases is linked to lesion formation at the focal CpG and subsequent long-patch repair. Our findings indicate that cytosine methylation has a broader mutational footprint than is commonly assumed.
Collapse
|
9
|
Nedelec B, Rozet JM, Fares Taie L. Genetic architecture of retinoic-acid signaling-associated ocular developmental defects. Hum Genet 2019; 138:937-955. [DOI: 10.1007/s00439-019-02052-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2019] [Accepted: 07/23/2019] [Indexed: 12/14/2022]
|
10
|
Muszewska A, Steczkiewicz K, Stepniewska-Dziubinska M, Ginalski K. Transposable elements contribute to fungal genes and impact fungal lifestyle. Sci Rep 2019; 9:4307. [PMID: 30867521 PMCID: PMC6416283 DOI: 10.1038/s41598-019-40965-0] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2018] [Accepted: 02/26/2019] [Indexed: 12/21/2022] Open
Abstract
The last decade brought a still growing experimental evidence of mobilome impact on host's gene expression. We systematically analysed genomic location of transposable elements (TEs) in 625 publicly available fungal genomes from the NCBI database in order to explore their potential roles in genome evolution and correlation with species' lifestyle. We found that non-autonomous TEs and remnant copies are evenly distributed across genomes. In consequence, they also massively overlap with regions annotated as genes, which suggests a great contribution of TE-derived sequences to host's coding genome. Younger and potentially active TEs cluster with one another away from genic regions. This non-randomness is a sign of either selection against insertion of TEs in gene proximity or target site preference among some types of TEs. Proteins encoded by genes with old transposable elements insertions have significantly less repeat and protein-protein interaction motifs but are richer in enzymatic domains. However, genes only proximal to TEs do not display any functional enrichment. Our findings show that adaptive cases of TE insertion remain a marginal phenomenon, and the overwhelming majority of TEs are evolving neutrally. Eventually, animal-related and pathogenic fungi have more TEs inserted into genes than fungi with other lifestyles. This is the first systematic, kingdom-wide study concerning mobile elements and their genomic neighbourhood. The obtained results should inspire further research concerning the roles TEs played in evolution and how they shape the life we know today.
Collapse
Affiliation(s)
- Anna Muszewska
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawinskiego 5A, 02-106, Warsaw, Poland.
| | - Kamil Steczkiewicz
- Laboratory of Bioinformatics and Systems Biology, CeNT, University of Warsaw, Zwirki i Wigury 93, 02-089, Warsaw, Poland
| | | | - Krzysztof Ginalski
- Laboratory of Bioinformatics and Systems Biology, CeNT, University of Warsaw, Zwirki i Wigury 93, 02-089, Warsaw, Poland
| |
Collapse
|
11
|
Transposons, p53 and Genome Security. Trends Genet 2018; 34:846-855. [PMID: 30195581 DOI: 10.1016/j.tig.2018.08.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Revised: 07/31/2018] [Accepted: 08/07/2018] [Indexed: 12/16/2022]
Abstract
p53, the most commonly mutated tumor suppressor, is a transcription factor known to regulate proliferation, senescence, and apoptosis. Compelling studies have found that p53 may prevent oncogenesis through effectors that are unrelated to these canonical processes and recent findings have uncovered ancient roles for p53 in the containment of mobile elements. Together, these developments raise the possibility that some p53-driven cancers could result from unrestrained transposons. Here, we explore evidence linking conserved features of p53 biology to the control of transposons. We also show how p53-deficient cells can be exploited to probe the behavior of transposons and illustrate how unrestrained transposons incited by p53 loss might contribute to human malignancies.
Collapse
|
12
|
Cvekl A, Zhao Y, McGreal R, Xie Q, Gu X, Zheng D. Evolutionary Origins of Pax6 Control of Crystallin Genes. Genome Biol Evol 2018; 9:2075-2092. [PMID: 28903537 PMCID: PMC5737492 DOI: 10.1093/gbe/evx153] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/14/2017] [Indexed: 12/19/2022] Open
Abstract
The birth of novel genes, including their cell-specific transcriptional control, is a major source of evolutionary innovation. The lens-preferred proteins, crystallins (vertebrates: α- and β/γ-crystallins), provide a gateway to study eye evolution. Diversity of crystallins was thought to originate from convergent evolution through multiple, independent formation of Pax6/PaxB-binding sites within the promoters of genes able to act as crystallins. Here, we propose that αB-crystallin arose from a duplication of small heat shock protein (Hspb1-like) gene accompanied by Pax6-site and heat shock element (HSE) formation, followed by another duplication to generate the αA-crystallin gene in which HSE was converted into another Pax6-binding site. The founding β/γ-crystallin gene arose from the ancestral Hspb1-like gene promoter inserted into a Ca2+-binding protein coding region, early in the cephalochordate/tunicate lineage. Likewise, an ancestral aldehyde dehydrogenase (Aldh) gene, through multiple gene duplications, expanded into a multigene family, with specific genes expressed in invertebrate lenses (Ω-crystallin/Aldh1a9) and both vertebrate lenses (η-crystallin/Aldh1a7 and Aldh3a1) and corneas (Aldh3a1). Collectively, the present data reconstruct the evolution of diverse crystallin gene families.
Collapse
Affiliation(s)
- Ales Cvekl
- Department of Ophthalmology and Visual Sciences, Albert Einstein College of Medicine, Bronx, New York.,Department of Genetics, Albert Einstein College of Medicine, Bronx, New York
| | - Yilin Zhao
- Department of Genetics, Albert Einstein College of Medicine, Bronx, New York
| | - Rebecca McGreal
- Department of Ophthalmology and Visual Sciences, Albert Einstein College of Medicine, Bronx, New York.,Department of Genetics, Albert Einstein College of Medicine, Bronx, New York
| | - Qing Xie
- Department of Ophthalmology and Visual Sciences, Albert Einstein College of Medicine, Bronx, New York.,Department of Genetics, Albert Einstein College of Medicine, Bronx, New York
| | - Xun Gu
- Program in Bioinformatics and Computational Biology, Department of Genetics, Development, and Cell Biology, Iowa State University
| | - Deyou Zheng
- Department of Genetics, Albert Einstein College of Medicine, Bronx, New York.,Department of Neurology, Albert Einstein College of Medicine, Bronx, New York.,Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York
| |
Collapse
|
13
|
Luscan R, Mechaussier S, Paul A, Tian G, Gérard X, Defoort-Dellhemmes S, Loundon N, Audo I, Bonnin S, LeGargasson JF, Dumont J, Goudin N, Garfa-Traoré M, Bras M, Pouliet A, Bessières B, Boddaert N, Sahel JA, Lyonnet S, Kaplan J, Cowan NJ, Rozet JM, Marlin S, Perrault I. Mutations in TUBB4B Cause a Distinctive Sensorineural Disease. Am J Hum Genet 2017; 101:1006-1012. [PMID: 29198720 DOI: 10.1016/j.ajhg.2017.10.010] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2017] [Accepted: 10/25/2017] [Indexed: 01/07/2023] Open
Abstract
Leber congenital amaurosis (LCA) is a neurodegenerative disease of photoreceptor cells that causes blindness within the first year of life. It occasionally occurs in syndromic metabolic diseases and plurisystemic ciliopathies. Using exome sequencing in a multiplex family and three simplex case subjects with an atypical association of LCA with early-onset hearing loss, we identified two heterozygous mutations affecting Arg391 in β-tubulin 4B isotype-encoding (TUBB4B). Inspection of the atomic structure of the microtubule (MT) protofilament reveals that the β-tubulin Arg391 residue contributes to a binding pocket that interacts with α-tubulin contained in the longitudinally adjacent αβ-heterodimer, consistent with a role in maintaining MT stability. Functional analysis in cultured cells overexpressing FLAG-tagged wild-type or mutant TUBB4B as well as in primary skin-derived fibroblasts showed that the mutant TUBB4B is able to fold, form αβ-heterodimers, and co-assemble into the endogenous MT lattice. However, the dynamics of growing MTs were consistently altered, showing that the mutations have a significant dampening impact on normal MT growth. Our findings provide a link between sensorineural disease and anomalies in MT behavior and describe a syndromic LCA unrelated to ciliary dysfunction.
Collapse
Affiliation(s)
- Romain Luscan
- Laboratory of Embryology and Genetics of Human Malformation, INSERM UMR1163, Institute of Genetic Diseases, Imagine and Paris Descartes University, 75015 Paris, France
| | - Sabrina Mechaussier
- Laboratory of Genetics in Ophthalmology (LGO), INSERM UMR1163, Institute of Genetic Diseases, Imagine and Paris Descartes University, 75015 Paris, France
| | - Antoine Paul
- Laboratory of Embryology and Genetics of Human Malformation, INSERM UMR1163, Institute of Genetic Diseases, Imagine and Paris Descartes University, 75015 Paris, France
| | - Guoling Tian
- Department of Biochemistry & Molecular Pharmacology, NYU Langone Medical Center, New York, NY 10016, USA
| | - Xavier Gérard
- Laboratory of Genetics in Ophthalmology (LGO), INSERM UMR1163, Institute of Genetic Diseases, Imagine and Paris Descartes University, 75015 Paris, France
| | - Sabine Defoort-Dellhemmes
- Service d'Exploration de la Vision et Neuro-ophtalmologie, Pôle d'Imagerie et Explorations Fonctionnelles, CHRU de Lille, Hôpital Roger Salengro, 59000 Lille, France
| | - Natalie Loundon
- Pediatric ENT Department, Hôpital Necker-Enfants Malades, APHP and Paris Descartes University, 75015 Paris, France
| | - Isabelle Audo
- Centre Hospitalier National d'Ophtalmologie des Quinze-Vingts, 75012 Paris, France
| | - Sophie Bonnin
- Ophthalmology Department, Hôpital Lariboisière, APHP and Paris Diderot University, 75010 Paris, France
| | - Jean-François LeGargasson
- Visual Exploration Department, Hôpital Lariboisière, APHP, Paris, Diderot University, 75010 Paris, France
| | - Julien Dumont
- Cell Division and Reproduction, Institut Jacques Monod, CNRS, University Paris Diderot, 75013 Paris, France
| | - Nicolas Goudin
- Cell Imaging Core Facility of the Structure Fédérative de Recherche Necker INSERM US24/CNRS UMS3633 Imagine and Paris Descartes University, 75015 Paris, France
| | - Meriem Garfa-Traoré
- Cell Imaging Core Facility of the Structure Fédérative de Recherche Necker INSERM US24/CNRS UMS3633 Imagine and Paris Descartes University, 75015 Paris, France
| | - Marc Bras
- Bioinformatics Platform, Imagine and Paris Descartes University, 75015 Paris, France
| | - Aurore Pouliet
- Genomics Platform, Imagine and Paris Descartes University, 75015 Paris, France
| | - Bettina Bessières
- Unité d'Embryo-foetopathologie, Hôpital Necker-Enfants Malades, APHP and Paris Descartes University, 75015 Paris, France
| | - Nathalie Boddaert
- Department of Pediatric Radiology, Hôpital Necker-Enfants Malades, APHP, Paris, Descartes University, 75015 Paris, France
| | - José-Alain Sahel
- Centre Hospitalier National d'Ophtalmologie des Quinze-Vingts, 75012 Paris, France
| | - Stanislas Lyonnet
- Laboratory of Embryology and Genetics of Human Malformation, INSERM UMR1163, Institute of Genetic Diseases, Imagine and Paris Descartes University, 75015 Paris, France
| | - Josseline Kaplan
- Laboratory of Genetics in Ophthalmology (LGO), INSERM UMR1163, Institute of Genetic Diseases, Imagine and Paris Descartes University, 75015 Paris, France
| | - Nicholas J Cowan
- Department of Biochemistry & Molecular Pharmacology, NYU Langone Medical Center, New York, NY 10016, USA
| | - Jean-Michel Rozet
- Laboratory of Genetics in Ophthalmology (LGO), INSERM UMR1163, Institute of Genetic Diseases, Imagine and Paris Descartes University, 75015 Paris, France.
| | - Sandrine Marlin
- Laboratory of Embryology and Genetics of Human Malformation, INSERM UMR1163, Institute of Genetic Diseases, Imagine and Paris Descartes University, 75015 Paris, France; Centre de Référence des Surdités Génétiques, Genetic Department, Hôpital Necker-Enfants Malades, APHP and Paris Descartes University, 75015 Paris, France.
| | - Isabelle Perrault
- Laboratory of Genetics in Ophthalmology (LGO), INSERM UMR1163, Institute of Genetic Diseases, Imagine and Paris Descartes University, 75015 Paris, France
| |
Collapse
|
14
|
Jiang X, Tang H, Ye Z, Lynch M. Insertion Polymorphisms of Mobile Genetic Elements in Sexual and Asexual Populations of Daphnia pulex. Genome Biol Evol 2017; 9:362-374. [PMID: 28057730 PMCID: PMC5381639 DOI: 10.1093/gbe/evw302] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/29/2016] [Indexed: 12/20/2022] Open
Abstract
Transposable elements (TEs) constitute a substantial portion of many eukaryotic genomes, and can in principle contribute to evolutionary innovation as well as genomic deterioration. Daphnia pulex serves as a useful model for studying TE dynamics as a potential cause and/or consequence of asexuality. We analyzed insertion polymorphisms of TEs in 20 sexual and 20 asexual isolates of D. pulex across North American from their available whole-genome sequencing data. Our results show that the total fraction of the derived sequences of TEs is not substantially different between asexual and sexual D. pulex isolates. However, in general, sexual clones contain fewer fixed TE insertions but more total insertion polymorphisms than asexual clones, supporting the hypothesis that sexual reproduction facilitates the spread and elimination of TEs. We identified nine asexual-specific fixed TE insertions, eight long terminal repeat retrotransposons, and one DNA transposon. By comparison, no sexual-specific fixed TE insertions were observed in our analysis. Furthermore, except one TE insertion located on a contig from chromosome 7, the other eight asexual-specific insertion sites are located on contigs from chromosome 9 that is known to be associated with obligate asexuality in D. pulex. We found that all nine asexual-specific fixed TE insertions can also be detected in some Daphnia pulicaria isolates, indicating that a substantial number of TE insertions in asexual D. pulex have been directly inherited from D. pulicaria during the origin of obligate asexuals.
Collapse
Affiliation(s)
- Xiaoqian Jiang
- Department of Biology, Indiana University, Bloomington, Indiana
| | - Haixu Tang
- School of Informatics and Computing, Indiana University, Bloomington, Indiana
| | - Zhiqiang Ye
- Department of Biology, Indiana University, Bloomington, Indiana
| | - Michael Lynch
- Department of Biology, Indiana University, Bloomington, Indiana
| |
Collapse
|
15
|
Bao F, LoVerso PR, Fisk JN, Zhurkin VB, Cui F. p53 binding sites in normal and cancer cells are characterized by distinct chromatin context. Cell Cycle 2017; 16:2073-2085. [PMID: 28820292 PMCID: PMC5731425 DOI: 10.1080/15384101.2017.1361064] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The tumor suppressor protein p53 interacts with DNA in a sequence-dependent manner. Thousands of p53 binding sites have been mapped genome-wide in normal and cancer cells. However, the way p53 selectively binds its cognate sites in different types of cells is not fully understood. Here, we performed a comprehensive analysis of 25 published p53 cistromes and identified 3,551 and 6,039 ‘high-confidence’ binding sites in normal and cancer cells, respectively. Our analysis revealed 2 distinct epigenetic features underlying p53-DNA interactions in vivo. First, p53 binding sites are associated with transcriptionally active histone marks (H3K4me3 and H3K36me3) in normal-cell chromatin, but with repressive histone marks (H3K27me3) in cancer-cell chromatin. Second, p53 binding sites in cancer cells are characterized by a lower level of DNA methylation than their counterparts in normal cells, probably related to global hypomethylation in cancers. Intriguingly, regardless of the cell type, p53 sites are highly enriched in the endogenous retroviral elements of the ERV1 family, highlighting the importance of this repeat family in shaping the transcriptional network of p53. Moreover, the p53 sites exhibit an unusual combination of chromatin patterns: high nucleosome occupancy and, at the same time, high sensitivity to DNase I. Our results suggest that p53 can access its target sites in a chromatin environment that is non-permissive to most DNA-binding transcription factors, which may allow p53 to act as a pioneer transcription factor in the context of chromatin.
Collapse
Affiliation(s)
- Feifei Bao
- a Thomas H. Gosnell School of Life Sciences , Rochester Institute of Technology , Rochester , NY , USA
| | - Peter R LoVerso
- b Laboratory of Cell Biology , National Cancer Institute , Bethesda , MD , USA
| | - Jeffrey N Fisk
- a Thomas H. Gosnell School of Life Sciences , Rochester Institute of Technology , Rochester , NY , USA
| | - Victor B Zhurkin
- b Laboratory of Cell Biology , National Cancer Institute , Bethesda , MD , USA
| | - Feng Cui
- a Thomas H. Gosnell School of Life Sciences , Rochester Institute of Technology , Rochester , NY , USA
| |
Collapse
|
16
|
Long HK, Prescott SL, Wysocka J. Ever-Changing Landscapes: Transcriptional Enhancers in Development and Evolution. Cell 2016; 167:1170-1187. [PMID: 27863239 PMCID: PMC5123704 DOI: 10.1016/j.cell.2016.09.018] [Citation(s) in RCA: 537] [Impact Index Per Article: 67.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2016] [Revised: 08/24/2016] [Accepted: 09/07/2016] [Indexed: 12/27/2022]
Abstract
A class of cis-regulatory elements, called enhancers, play a central role in orchestrating spatiotemporally precise gene-expression programs during development. Consequently, divergence in enhancer sequence and activity is thought to be an important mediator of inter- and intra-species phenotypic variation. Here, we give an overview of emerging principles of enhancer function, current models of enhancer architecture, genomic substrates from which enhancers emerge during evolution, and the influence of three-dimensional genome organization on long-range gene regulation. We discuss intricate relationships between distinct elements within complex regulatory landscapes and consider their potential impact on specificity and robustness of transcriptional regulation.
Collapse
Affiliation(s)
- Hannah K Long
- Department of Chemical and Systems Biology, Stanford School of Medicine, Stanford University, Stanford, CA 94305, USA; Institute of Stem Cell Biology and Regenerative Medicine, Stanford School of Medicine, Stanford University, Stanford, CA 94305, USA
| | - Sara L Prescott
- Department of Chemical and Systems Biology, Stanford School of Medicine, Stanford University, Stanford, CA 94305, USA; Department of Developmental Biology, Stanford School of Medicine, Stanford University, Stanford, CA 94305, USA
| | - Joanna Wysocka
- Department of Chemical and Systems Biology, Stanford School of Medicine, Stanford University, Stanford, CA 94305, USA; Institute of Stem Cell Biology and Regenerative Medicine, Stanford School of Medicine, Stanford University, Stanford, CA 94305, USA; Department of Developmental Biology, Stanford School of Medicine, Stanford University, Stanford, CA 94305, USA; Howard Hughes Medical Institute, Stanford School of Medicine, Stanford University, Stanford, CA 94305, USA.
| |
Collapse
|
17
|
Penzkofer T, Jäger M, Figlerowicz M, Badge R, Mundlos S, Robinson PN, Zemojtel T. L1Base 2: more retrotransposition-active LINE-1s, more mammalian genomes. Nucleic Acids Res 2016; 45:D68-D73. [PMID: 27924012 PMCID: PMC5210629 DOI: 10.1093/nar/gkw925] [Citation(s) in RCA: 85] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2016] [Revised: 09/28/2016] [Accepted: 10/05/2016] [Indexed: 12/28/2022] Open
Abstract
LINE-1 (L1) insertions comprise as much as 17% of the human genome sequence, and similar proportions have been recorded for other mammalian species. Given the established role of L1 retrotransposons in shaping mammalian genomes, it becomes an important task to track and annotate the sources of this activity: full length elements, able to encode the cis and trans acting components of the retrotransposition machinery. The L1Base database (http://l1base.charite.de) contains annotated full-length sequences of LINE-1 transposons including putatively active L1s. For the new version of L1Base, a LINE-1 annotation tool, L1Xplorer, has been used to mine potentially active L1 retrotransposons from the reference genome sequences of 17 mammals. The current release of the human genome, GRCh38, contains 146 putatively active L1 elements or full length intact L1 elements (FLIs). The newest versions of the mouse, GRCm38 and the rat, Rnor_6.0, genomes contain 2811 and 492 FLIs, respectively. Most likely reflecting the current level of completeness of the genome project, the latest reference sequence of the common chimpanzee genome, PT 2.19, only contains 19 FLIs. Of note, the current assemblies of the dog, CF 3.1 and the sheep, OA 3.1, genomes contain 264 and 598 FLIs, respectively. Further developments in the new version of L1Base include an updated website with implementation of modern web server technologies. including a more responsive design for an improved user experience, as well as the addition of data sharing capabilities for L1Xplorer annotation.
Collapse
Affiliation(s)
- Tobias Penzkofer
- Department of Radiology, Charité-Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, Germany
| | - Marten Jäger
- Institut für Medizinische Genetik und Humangenetik, Charité-Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, Germany
| | - Marek Figlerowicz
- Institute of Bioorganic Chemistry, Polish Academy of Sciences, 60-569 Poznan, Poland
| | - Richard Badge
- Department of Genetics, University of Leicester, Leicester, LE1 7RH, UK
| | - Stefan Mundlos
- Institut für Medizinische Genetik und Humangenetik, Charité-Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, Germany
| | - Peter N Robinson
- Institut für Medizinische Genetik und Humangenetik, Charité-Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, Germany.,The Jackson Laboratory for Genomic medicine, 10 Discovery Drive, Farmington, CT 06032, USA
| | - Tomasz Zemojtel
- Institut für Medizinische Genetik und Humangenetik, Charité-Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, Germany .,Institute of Bioorganic Chemistry, Polish Academy of Sciences, 60-569 Poznan, Poland
| |
Collapse
|
18
|
Kagawa T, Oka A, Kobayashi Y, Hiasa Y, Kitamura T, Sakugawa H, Adachi Y, Anzai K, Tsuruya K, Arase Y, Hirose S, Shiraishi K, Shiina T, Sato T, Wang T, Tanaka M, Hayashi H, Kawabe N, Robinson PN, Zemojtel T, Mine T. Recessive inheritance of population-specific intronic LINE-1 insertion causes a rotor syndrome phenotype. Hum Mutat 2015; 36:327-32. [PMID: 25546334 DOI: 10.1002/humu.22745] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2014] [Accepted: 12/15/2014] [Indexed: 11/06/2022]
Abstract
Sequences of long-interspersed elements (LINE-1, L1) make up ∼17% of the human genome. De novo insertions of retrotransposition-active L1s can result in genetic diseases. It has been recently shown that the homozygous inactivation of two adjacent genes SLCO1B1 and SLCO1B3 encoding organic anion transporting polypeptides OATP1B1 and OATP1B3 causes a benign recessive disease presenting with conjugated hyperbilirubinemia, Rotor syndrome. Here, we examined SLCO1B1 and SLCO1B3 genes in six Japanese diagnosed with Rotor syndrome on the basis of laboratory data and laparoscopy. All six Japanese patients were homozygous for the c.1738C>T nonsense mutation in SLCO1B1 and homozygous for the insertion of a ∼6.1-kbp L1 retrotransposon in intron 5 of SLCO1B3, which altogether make up a Japanese-specific haplotype. RNA analysis revealed that the L1 insertion induced deleterious splicing resulting in SLCO1B3 transcripts lacking exon 5 or exons 5-7 and containing premature stop codons. The expression of OATP1B1 and OATP1B3 proteins was not detected in liver tissues. This is the first documented case of a population-specific polymorphic intronic L1 transposon insertion contributing to molecular etiology of recessive genetic disease. Since L1 activity in human genomes is currently seen as a major source of individual genetic variation, further investigations are warranted to determine whether this phenomenon results in other autosomal-recessive diseases.
Collapse
Affiliation(s)
- Tatehiro Kagawa
- Division of Gastroenterology, Department of Internal Medicine, Tokai University School of Medicine, Isehara, Japan
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
19
|
When Competing Viruses Unify: Evolution, Conservation, and Plasticity of Genetic Identities. J Mol Evol 2015; 80:305-18. [PMID: 26014757 DOI: 10.1007/s00239-015-9683-y] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2015] [Accepted: 05/12/2015] [Indexed: 02/06/2023]
Abstract
In the early 1970s, Manfred Eigen and colleagues developed the quasispecies model (qs) for the population-based origin of RNAs representing the early genetic code. The Eigen idea is basically that a halo of mutants is generated by error-prone replication around the master fittest type which will behave similarly as a biological population. But almost from the start, very interesting and unexpected observations were made regarding competition versus co-operation which suggested more complex interactions. It thus became increasingly clear that although viruses functioned similar to biological species, their behavior was much more complex than the original theory could explain, especially adaptation without changing the consensus involving minority populations. With respect to the origin of natural codes, meaning, and code-use in interactions (communication), it also became clear that individual fittest type-based mechanisms were likewise unable to explain the origin of natural codes such as the genetic code with their context- and consortia-dependence (pragmatic nature). This, instead, required the participation of groups of agents competent in the code and able to edit code because natural codes do not code themselves. Three lines of inquiry, experimental virology, quasispecies theory, and the study of natural codes converged to indicate that consortia of co-operative RNA agents such as viruses must be involved in the fitness of RNA and its involvement in communication, i.e., code-competent interactions. We called this co-operative form quasispecies consortia (qs-c). They are the essential agents that constitute the possibility of evolution of biological group identity. Finally, the basic interactional motifs for the emergence of group identity, communication, and co-operation-together with its opposing functions-are explained by the "Gangen" hypothesis.
Collapse
|
20
|
Glinsky GV. Transposable Elements and DNA Methylation Create in Embryonic Stem Cells Human-Specific Regulatory Sequences Associated with Distal Enhancers and Noncoding RNAs. Genome Biol Evol 2015; 7:1432-54. [PMID: 25956794 PMCID: PMC4494056 DOI: 10.1093/gbe/evv081] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Despite significant progress in the structural and functional characterization of the human genome, understanding of the mechanisms underlying the genetic basis of human phenotypic uniqueness remains limited. Here, I report that transposable element-derived sequences, most notably LTR7/HERV-H, LTR5_Hs, and L1HS, harbor 99.8% of the candidate human-specific regulatory loci (HSRL) with putative transcription factor-binding sites in the genome of human embryonic stem cells (hESC). A total of 4,094 candidate HSRL display selective and site-specific binding of critical regulators (NANOG [Nanog homeobox], POU5F1 [POU class 5 homeobox 1], CCCTC-binding factor [CTCF], Lamin B1), and are preferentially located within the matrix of transcriptionally active DNA segments that are hypermethylated in hESC. hESC-specific NANOG-binding sites are enriched near the protein-coding genes regulating brain size, pluripotency long noncoding RNAs, hESC enhancers, and 5-hydroxymethylcytosine-harboring regions immediately adjacent to binding sites. Sequences of only 4.3% of hESC-specific NANOG-binding sites are present in Neanderthals’ genome, suggesting that a majority of these regulatory elements emerged in Modern Humans. Comparisons of estimated creation rates of novel TF-binding sites revealed that there was 49.7-fold acceleration of creation rates of NANOG-binding sites in genomes of Chimpanzees compared with the mouse genomes and further 5.7-fold acceleration in genomes of Modern Humans compared with the Chimpanzees genomes. Preliminary estimates suggest that emergence of one novel NANOG-binding site detectable in hESC required 466 years of evolution. Pathway analysis of coding genes that have hESC-specific NANOG-binding sites within gene bodies or near gene boundaries revealed their association with physiological development and functions of nervous and cardiovascular systems, embryonic development, behavior, as well as development of a diverse spectrum of pathological conditions such as cancer, diseases of cardiovascular and reproductive systems, metabolic diseases, multiple neurological and psychological disorders. A proximity placement model is proposed explaining how a 33–47% excess of NANOG, CTCF, and POU5F1 proteins immobilized on a DNA scaffold may play a functional role at distal regulatory elements.
Collapse
Affiliation(s)
- Gennadi V Glinsky
- Institute of Engineering in Medicine, University of California, San Diego The Stanford University School of Medicine, Department of Surgery, Stanford, California
| |
Collapse
|
21
|
Botcheva K. p53 binding to human genome: crowd control navigation in chromatin context. Front Genet 2014; 5:447. [PMID: 25566329 PMCID: PMC4273661 DOI: 10.3389/fgene.2014.00447] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2014] [Accepted: 12/05/2014] [Indexed: 11/22/2022] Open
Abstract
p53 is the most studied human protein because of its role in maintaining genomic stability. Binding to genomic targets is essential for transcription-dependent p53 tumor suppression, but how p53 selects targets remains unclear. Here, the impact of chromatin context on p53 genome-wide binding and targets selection is discussed. It is proposed that p53 genomic binding serves not only to regulate transcription, but to sense epigenomic changes threatening the genomic integrity. The problem of p53 navigating the human genome is discussed with respect to the degenerate p53 binding motif. This discussion relates to the fundamental problem of DNA binding factors navigating large genomes in search for cognate binding sites.
Collapse
Affiliation(s)
- Krassimira Botcheva
- Cell and Molecular Biology Department, Life Sciences Division, Lawrence Berkeley National Laboratory , Berkeley, CA, USA
| |
Collapse
|
22
|
Cell context dependent p53 genome-wide binding patterns and enrichment at repeats. PLoS One 2014; 9:e113492. [PMID: 25415302 PMCID: PMC4240582 DOI: 10.1371/journal.pone.0113492] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2014] [Accepted: 10/23/2014] [Indexed: 12/02/2022] Open
Abstract
The p53 ability to elicit stress specific and cell type specific responses is well recognized, but how that specificity is established remains to be defined. Whether upon activation p53 binds to its genomic targets in a cell type and stress type dependent manner is still an open question. Here we show that the p53 binding to the human genome is selective and cell context-dependent. We mapped the genomic binding sites for the endogenous wild type p53 protein in the human cancer cell line HCT116 and compared them to those we previously determined in the normal cell line IMR90. We report distinct p53 genome-wide binding landscapes in two different cell lines, analyzed under the same treatment and experimental conditions, using the same ChIP-seq approach. This is evidence for cell context dependent p53 genomic binding. The observed differences affect the p53 binding sites distribution with respect to major genomic and epigenomic elements (promoter regions, CpG islands and repeats). We correlated the high-confidence p53 ChIP-seq peaks positions with the annotated human repeats (UCSC Human Genome Browser) and observed both common and cell line specific trends. In HCT116, the p53 binding was specifically enriched at LINE repeats, compared to IMR90 cells. The p53 genome-wide binding patterns in HCT116 and IMR90 likely reflect the different epigenetic landscapes in these two cell lines, resulting from cancer-associated changes (accumulated in HCT116) superimposed on tissue specific differences (HCT116 has epithelial, while IMR90 has mesenchymal origin). Our data support the model for p53 binding to the human genome in a highly selective manner, mobilizing distinct sets of genes, contributing to distinct pathways.
Collapse
|
23
|
Villarreal LP. Force for ancient and recent life: viral and stem-loop RNA consortia promote life. Ann N Y Acad Sci 2014; 1341:25-34. [PMID: 25376951 DOI: 10.1111/nyas.12565] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Lytic viruses were thought to kill the most numerous host (i.e., kill the winner). But persisting viruses/defectives can also protect against viruses, especially in a ubiquitous virosphere. In 1991, Yarmolinsky et al. discovered the addiction modules of P1 phage, in which opposing toxic and protective functions stabilize persistence. Subsequently, I proposed that lytic and persisting cryptic virus also provide addiction modules that promote group identity. In eukaryotes (and the RNA world), a distinct RNA virus-host relationship exists. Retrovirurses/retroposons are major contributors to eukaryotic genomes. Eukaryotic complexity appears to be mostly mediated by regulatory complexity involving noncoding retroposon-derived RNA. RNA viruses evolve via quasispecies, which contain cooperating, minority, and even opposing RNA types. Quasispecies can also demonstrate group preclusion (e.g., hepatitis C). Stem-loop RNA domains are found in long terminal repeats (and viral RNA) and mediate viral regulation/identity. Thus, stem-loop RNAs may be ancestral regulators. I consider the RNA (ribozyme) world scenario from the perspective of addiction modules and cooperating quasispecies (i.e., subfunctional agents that establish group identity). Such an RNA collective resembles a "gang" but requires the simultaneous emergence of endonuclease, ligase, cooperative catalysis, group identity, and history markers (RNA). I call such a collective a gangen (pathway to gang) needed for life to emerge.
Collapse
Affiliation(s)
- Luis P Villarreal
- Center for Virus Research, University of California, Irvine, California
| |
Collapse
|
24
|
Dynamic Alu methylation during normal development, aging, and tumorigenesis. BIOMED RESEARCH INTERNATIONAL 2014; 2014:784706. [PMID: 25243180 PMCID: PMC4163490 DOI: 10.1155/2014/784706] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/10/2014] [Accepted: 08/16/2014] [Indexed: 12/15/2022]
Abstract
DNA methylation primarily occurs on CpG dinucleotides and plays an important role in transcriptional regulations during tissue development and cell differentiation. Over 25% of CpG dinucleotides in the human genome reside within Alu elements, the most abundant human repeats. The methylation of Alu elements is an important mechanism to suppress Alu transcription and subsequent retrotransposition. Decades of studies revealed that Alu methylation is highly dynamic during early development and aging. Recently, many environmental factors were shown to have a great impact on Alu methylation. In addition, aberrant Alu methylation has been documented to be an early event in many tumors and Alu methylation levels have been associated with tumor aggressiveness. The assessment of the Alu methylation has become an important approach for early diagnosis and/or prognosis of cancer. This review focuses on the dynamic Alu methylation during development, aging, and tumor genesis. The cause and consequence of Alu methylation changes will be discussed.
Collapse
|
25
|
Abstract
Alus are transposable elements belonging to the short interspersed element family. They occupy over 10% of human genome and have been spreading through genomes over the past 65 million years. In the past, they were considered junk DNA with little function that took up genome volumes. Today, Alus and other transposable elements emerge to be key players in cellular function, including genomic activities, gene expression regulations, and evolution. Here we summarize the current understanding of Alu function in genome and gene expression regulation in human cell nuclei.
Collapse
Affiliation(s)
- Chen Wang
- Department of Cell and Molecular Biology; Northwestern University; Feinberg School of Medicine; Chicago, IL USA
| | - Sui Huang
- Department of Cell and Molecular Biology; Northwestern University; Feinberg School of Medicine; Chicago, IL USA
| |
Collapse
|
26
|
Ichiyanagi K. Epigenetic regulation of transcription and possible functions of mammalian short interspersed elements, SINEs. Genes Genet Syst 2014; 88:19-29. [PMID: 23676707 DOI: 10.1266/ggs.88.19] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Short interspersed elements (SINEs) are a class of retrotransposons, which amplify their copy numbers in their host genomes by retrotransposition. More than a million copies of SINEs are present in a mammalian genome, constituting over 10% of the total genomic sequence. In contrast to the other two classes of retrotransposons, long interspersed elements (LINEs) and long terminal repeat (LTR) elements, SINEs are transcribed by RNA polymerase III. However, like LINEs and LTR elements, the SINE transcription is likely regulated by epigenetic mechanisms such as DNA methylation, at least for human Alu and mouse B1. Whereas SINEs and other transposable elements have long been thought as selfish or junk DNA, recent studies have revealed that they play functional roles at their genomic locations, for example, as distal enhancers, chromatin boundaries and binding sites of many transcription factors. These activities imply that SINE retrotransposition has shaped the regulatory network and chromatin landscape of their hosts. Whereas it is thought that the epigenetic mechanisms were originated as a host defense system against proliferation of parasitic elements, this review discusses a possibility that the same mechanisms are also used to regulate the SINE-derived functions.
Collapse
Affiliation(s)
- Kenji Ichiyanagi
- Division of Epigenomics, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan.
| |
Collapse
|
27
|
Muszewska A, Steczkiewicz K, Ginalski K. DIRS and Ngaro Retrotransposons in Fungi. PLoS One 2013; 8:e76319. [PMID: 24086727 PMCID: PMC3783388 DOI: 10.1371/journal.pone.0076319] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2013] [Accepted: 08/23/2013] [Indexed: 11/19/2022] Open
Abstract
Retrotransposons with a tyrosine recombinase (YR) have been discovered recently and lack thorough annotation in fungi. YR retrotransposons are divided into 3 groups: DIRS, Ngaro and VIPER (known only from kinetoplastida). We used comparative genomics to investigate the evolutionary patterns of retrotransposons in the fungal kingdom. The identification of both functional and remnant elements provides a unique view on both recent and past transposition activity. Our searches covering a wide range of fungal genomes allowed us to identify 2241 YR retrotransposons. Based on CLANS clustering of concatenated sequences of the reverse transcriptase (RT), RNase H (RH), DNA N-6-adenine-methyltransferase (MT) and YR protein domains we propose a revised classification of YR elements expanded by two new categories of Ngaro elements. A phylogenetic analysis of 477 representatives supports this observation and additionally demonstrates that DIRS and Ngaro abundance changed independently in Basidiomycota and Blastocladiomycota/Mucoromycotina/Kixellomycotina. Interestingly, a single remnant Ngaro element could be identified in an Ascomycota genome. Our analysis revealed also that 3 Pucciniomycotina taxa, known for their overall mobile element abundance and big genome size, encode an elevated number of Ngaro retrotransposons. Considering the presence of DIRS elements in all analyzed Mucoromycotina, Kickxellomycotina and Blastocladiomycota genomes one might assume a common origin of fungal DIRS retrotransposons with a loss in Dicarya. Ngaro elements described to date from Opisthokonta, seem to have invaded the common ancestor of Agaricomycotina and Pucciniomycotina after Ustilagomycotina divergence. Yet, most of analyzed genomes are devoid of YR elements and most identified retrotransposons are incomplete.
Collapse
Affiliation(s)
- Anna Muszewska
- Laboratory of Bioinformatics and Systems Biology, CeNT, University of Warsaw, Warsaw, Poland
| | - Kamil Steczkiewicz
- Laboratory of Bioinformatics and Systems Biology, CeNT, University of Warsaw, Warsaw, Poland
| | - Krzysztof Ginalski
- Laboratory of Bioinformatics and Systems Biology, CeNT, University of Warsaw, Warsaw, Poland
| |
Collapse
|
28
|
Lowe CB, Haussler D. 29 mammalian genomes reveal novel exaptations of mobile elements for likely regulatory functions in the human genome. PLoS One 2012; 7:e43128. [PMID: 22952639 PMCID: PMC3428314 DOI: 10.1371/journal.pone.0043128] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2012] [Accepted: 07/17/2012] [Indexed: 11/18/2022] Open
Abstract
Recent research supports the view that changes in gene regulation, as opposed to changes in the genes themselves, play a significant role in morphological evolution. Gene regulation is largely dependent on transcription factor binding sites. Researchers are now able to use the available 29 mammalian genomes to measure selective constraint at the level of binding sites. This detailed map of constraint suggests that mammalian genomes co-opt fragments of mobile elements to act as gene regulatory sequence on a large scale. In the human genome we detect over 280,000 putative regulatory elements, totaling approximately 7 Mb of sequence, that originated as mobile element insertions. These putative regulatory regions are conserved non-exonic elements (CNEEs), which show considerable cross-species constraint and signatures of continued negative selection in humans, yet do not appear in a known mature transcript. These putative regulatory elements were co-opted from SINE, LINE, LTR and DNA transposon insertions. We demonstrate that at least 11%, and an estimated 20%, of gene regulatory sequence in the human genome showing cross-species conservation was co-opted from mobile elements. The location in the genome of CNEEs co-opted from mobile elements closely resembles that of CNEEs in general, except in the centers of the largest gene deserts where recognizable co-option events are relatively rare. We find that regions of certain mobile element insertions are more likely to be held under purifying selection than others. In particular, we show 6 examples where paralogous instances of an often co-opted mobile element region define a sequence motif that closely matches a transcription factor's binding profile.
Collapse
Affiliation(s)
- Craig B. Lowe
- Center for Biomolecular Science and Engineering, University of California Santa Cruz, Santa Cruz, California, United States of America
| | - David Haussler
- Center for Biomolecular Science and Engineering, University of California Santa Cruz, Santa Cruz, California, United States of America
- Howard Hughes Medical Institute, University of California Santa Cruz, Santa Cruz, California, United States of America
| |
Collapse
|
29
|
Rebollo R, Romanish MT, Mager DL. Transposable elements: an abundant and natural source of regulatory sequences for host genes. Annu Rev Genet 2012; 46:21-42. [PMID: 22905872 DOI: 10.1146/annurev-genet-110711-155621] [Citation(s) in RCA: 352] [Impact Index Per Article: 29.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The fact that transposable elements (TEs) can influence host gene expression was first recognized more than 50 years ago. However, since that time, TEs have been widely regarded as harmful genetic parasites-selfish elements that are rarely co-opted by the genome to serve a beneficial role. Here, we survey recent findings that relate to TE impact on host genes and remind the reader that TEs, in contrast to other noncoding parts of the genome, are uniquely suited to gene regulatory functions. We review recent studies that demonstrate the role of TEs in establishing and rewiring gene regulatory networks and discuss the overall ubiquity of exaptation. We suggest that although individuals within a population can be harmed by the deleterious effects of new TE insertions, the presence of TE sequences in a genome is of overall benefit to the population.
Collapse
Affiliation(s)
- Rita Rebollo
- Terry Fox Laboratory, British Columbia Cancer Agency, Vancouver, Canada.
| | | | | |
Collapse
|
30
|
Zemojtel T, Vingron M. P53 binding sites in transposons. Front Genet 2012; 3:40. [PMID: 22448161 PMCID: PMC3308033 DOI: 10.3389/fgene.2012.00040] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2012] [Accepted: 03/01/2012] [Indexed: 11/13/2022] Open
Affiliation(s)
- Tomasz Zemojtel
- Department of Computational Molecular Biology, Max-Planck-Institute for Molecular Genetics Berlin, Germany
| | | |
Collapse
|
31
|
Göke J, Schulz MH, Lasserre J, Vingron M. Estimation of pairwise sequence similarity of mammalian enhancers with word neighbourhood counts. ACTA ACUST UNITED AC 2012; 28:656-63. [PMID: 22247280 PMCID: PMC3289921 DOI: 10.1093/bioinformatics/bts028] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
MOTIVATION The identity of cells and tissues is to a large degree governed by transcriptional regulation. A major part is accomplished by the combinatorial binding of transcription factors at regulatory sequences, such as enhancers. Even though binding of transcription factors is sequence-specific, estimating the sequence similarity of two functionally similar enhancers is very difficult. However, a similarity measure for regulatory sequences is crucial to detect and understand functional similarities between two enhancers and will facilitate large-scale analyses like clustering, prediction and classification of genome-wide datasets. RESULTS We present the standardized alignment-free sequence similarity measure N2, a flexible framework that is defined for word neighbourhoods. We explore the usefulness of adding reverse complement words as well as words including mismatches into the neighbourhood. On simulated enhancer sequences as well as functional enhancers in mouse development, N2 is shown to outperform previous alignment-free measures. N2 is flexible, faster than competing methods and less susceptible to single sequence noise and the occurrence of repetitive sequences. Experiments on the mouse enhancers reveal that enhancers active in different tissues can be separated by pairwise comparison using N2. CONCLUSION N2 represents an improvement over previous alignment-free similarity measures without compromising speed, which makes it a good candidate for large-scale sequence comparison of regulatory sequences. AVAILABILITY The software is part of the open-source C++ library SeqAn (www.seqan.de) and a compiled version can be downloaded at http://www.seqan.de/projects/alf.html. SUPPLEMENTARY INFORMATION Supplementary data are available at Bioinformatics online.
Collapse
Affiliation(s)
- Jonathan Göke
- Department for Computational Molecular Biology, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany.
| | | | | | | |
Collapse
|
32
|
Kines KJ, Belancio VP. Expressing genes do not forget their LINEs: transposable elements and gene expression. FRONT BIOSCI-LANDMRK 2012; 17:1329-44. [PMID: 22201807 DOI: 10.2741/3990] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Historically the accumulated mass of mammalian transposable elements (TEs), particularly those located within gene boundaries, was viewed as a genetic burden potentially detrimental to the genomic landscape. This notion has been strengthened by the discovery that transposable sequences can alter the architecture of the transcriptome, not only through insertion, but also long after the integration process is completed. Insertions previously considered harmless are now known to impact the expression of host genes via modification of the transcript quality or quantity, transcriptional interference, or by the control of pathways that affect the mRNA life-cycle. Conversely, several examples of the evolutionary advantageous impact of TEs on the host gene structure that diversified the cellular transcriptome are reported. TE-induced changes in gene expression can be tissue- or disease-specific, raising the possibility that the impact of TE sequences may vary during development, among normal cell types, and between normal and disease-affected tissues. The understanding of the rules and abundance of TE-interference with gene expression is in its infancy, and its contribution to human disease and/or evolution remains largely unexplored.
Collapse
Affiliation(s)
- Kristine J Kines
- Department of Structural and Cellular Biology, Tulane University School of Medicine, Tulane University Cancer Center and Tulane Center for Aging
| | | |
Collapse
|
33
|
Muszewska A, Hoffman-Sommer M, Grynberg M. LTR retrotransposons in fungi. PLoS One 2011; 6:e29425. [PMID: 22242120 PMCID: PMC3248453 DOI: 10.1371/journal.pone.0029425] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2011] [Accepted: 11/28/2011] [Indexed: 01/17/2023] Open
Abstract
Transposable elements with long terminal direct repeats (LTR TEs) are one of the best studied groups of mobile elements. They are ubiquitous elements present in almost all eukaryotic genomes. Their number and state of conservation can be a highlight of genome dynamics. We searched all published fungal genomes for LTR-containing retrotransposons, including both complete, functional elements and remnant copies. We identified a total of over 66,000 elements, all of which belong to the Ty1/Copia or Ty3/Gypsy superfamilies. Most of the detected Gypsy elements represent Chromoviridae, i.e. they carry a chromodomain in the pol ORF. We analyzed our data from a genome-ecology perspective, looking at the abundance of various types of LTR TEs in individual genomes and at the highest-copy element from each genome. The TE content is very variable among the analyzed genomes. Some genomes are very scarce in LTR TEs (<50 elements), others demonstrate huge expansions (>8000 elements). The data shows that transposon expansions in fungi usually involve an increase both in the copy number of individual elements and in the number of element types. The majority of the highest-copy TEs from all genomes are Ty3/Gypsy transposons. Phylogenetic analysis of these elements suggests that TE expansions have appeared independently of each other, in distant genomes and at different taxonomical levels. We also analyzed the evolutionary relationships between protein domains encoded by the transposon pol ORF and we found that the protease is the fastest evolving domain whereas reverse transcriptase and RNase H evolve much slower and in correlation with each other.
Collapse
Affiliation(s)
- Anna Muszewska
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland.
| | | | | |
Collapse
|
34
|
Abstract
Alu elements are primate-specific repeats and comprise 11% of the human genome. They have wide-ranging influences on gene expression. Their contribution to genome evolution, gene regulation and disease is reviewed.
Collapse
|
35
|
de Andrade A, Wang M, Bonaldo MF, Xie H, Soares MB. Genetic and epigenetic variations contributed by Alu retrotransposition. BMC Genomics 2011; 12:617. [PMID: 22185517 PMCID: PMC3272032 DOI: 10.1186/1471-2164-12-617] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2011] [Accepted: 12/20/2011] [Indexed: 12/16/2022] Open
Abstract
Background De novo retrotransposition of Alu elements has been recognized as a major driver for insertion polymorphisms in human populations. In this study, we exploited Alu-anchored bisulfite PCR libraries to identify evolutionarily recent Alu element insertions, and to investigate their genetic and epigenetic variation. Results A total of 327 putatively recent Alu insertions were identified, altogether represented by 1,762 sequence reads. Nearly all such de novo retrotransposition events (316/327) were novel. Forty-seven out of forty-nine randomly selected events, corresponding to nineteen genomic loci, were sequence-verified. Alu element insertions remained hemizygous in one or more individuals in sixteen of the nineteen genomic loci. The Alu elements were found to be enriched for young Alu families with characteristic sequence features, such as the presence of a longer poly(A) tail. In addition, we documented the occurrence of a duplication of the AT-rich target site in their immediate flanking sequences, a hallmark of retrotransposition. Furthermore, we found the sequence motif (TT/AAAA) that is recognized by the ORF2P protein encoded by LINE-1 in their 5'-flanking regions, consistent with the fact that Alu retrotransposition is facilitated by LINE-1 elements. While most of these Alu elements were heavily methylated, we identified an Alu localized 1.5 kb downstream of TOMM5 that exhibited a completely unmethylated left arm. Interestingly, we observed differential methylation of its immediate 5' and 3' flanking CpG dinucleotides, in concordance with the unmethylated and methylated statuses of its internal 5' and 3' sequences, respectively. Importantly, TOMM5's CpG island and the 3 Alu repeats and 1 MIR element localized upstream of this newly inserted Alu were also found to be unmethylated. Methylation analyses of two additional genomic loci revealed no methylation differences in CpG dinucleotides flanking the Alu insertion sites in the two homologous chromosomes, irrespective of the presence or absence of the insertion. Conclusions We anticipate that the combination of methodologies utilized in this study, which included repeat-anchored bisulfite PCR sequencing and the computational analysis pipeline herein reported, will prove invaluable for the generation of genetic and epigenetic variation maps.
Collapse
Affiliation(s)
- Alexandre de Andrade
- Falk Brain Tumor Center, Cancer Biology and Epigenomics Program, Children's Memorial Research Center, Chicago, IL 60614-3394, USA
| | | | | | | | | |
Collapse
|
36
|
Botcheva K, McCorkle SR, McCombie WR, Dunn JJ, Anderson CW. Distinct p53 genomic binding patterns in normal and cancer-derived human cells. Cell Cycle 2011; 10:4237-49. [PMID: 22127205 DOI: 10.4161/cc.10.24.18383] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
We report here genome-wide analysis of the tumor suppressor p53 binding sites in normal human cells. 743 high-confidence ChIP-seq peaks representing putative genomic binding sites were identified in normal IMR90 fibroblasts using a reference chromatin sample. More than 40% were located within 2 kb of a transcription start site (TSS), a distribution similar to that documented for individually studied, functional p53 binding sites and, to date, not observed by previous p53 genome-wide studies. Nearly half of the high-confidence binding sites in the IMR90 cells reside in CpG islands, in marked contrast to sites reported in cancer-derived cells. The distinct genomic features of the IMR90 binding sites do not reflect a distinct preference for specific sequences, since the de novo developed p53 motif based on our study is similar to those reported by genome-wide studies of cancer cells. More likely, the different chromatin landscape in normal, compared with cancer-derived cells, influences p53 binding via modulating availability of the sites. We compared the IMR90 ChIPseq peaks to the recently published IMR90 methylome and demonstrated that they are enriched at hypomethylated DNA. Our study represents the first genome-wide, de novo mapping of p53 binding sites in normal human cells and reveals that p53 binding sites reside in distinct genomic landscapes in normal and cancer-derived human cells.
Collapse
|
37
|
Pandey R, Mandal AK, Jha V, Mukerji M. Heat shock factor binding in Alu repeats expands its involvement in stress through an antisense mechanism. Genome Biol 2011; 12:R117. [PMID: 22112862 PMCID: PMC3334603 DOI: 10.1186/gb-2011-12-11-r117] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2011] [Revised: 11/09/2011] [Accepted: 11/23/2011] [Indexed: 01/22/2023] Open
Abstract
Background Alu RNAs are present at elevated levels in stress conditions and, consequently, Alu repeats are increasingly being associated with the physiological stress response. Alu repeats are known to harbor transcription factor binding sites that modulate RNA pol II transcription and Alu RNAs act as transcriptional co-repressors through pol II binding in the promoter regions of heat shock responsive genes. An observation of a putative heat shock factor (HSF) binding site in Alu led us to explore whether, through HSF binding, these elements could further contribute to the heat shock response repertoire. Results Alu density was significantly enriched in transcripts that are down-regulated following heat shock recovery in HeLa cells. ChIP analysis confirmed HSF binding to a consensus motif exhibiting positional conservation across various Alu subfamilies, and reporter constructs demonstrated a sequence-specific two-fold induction of these sites in response to heat shock. These motifs were over-represented in the genic regions of down-regulated transcripts in antisense oriented Alus. Affymetrix Exon arrays detected antisense signals in a significant fraction of the down-regulated transcripts, 50% of which harbored HSF sites within 5 kb. siRNA knockdown of the selected antisense transcripts led to the over-expression, following heat shock, of their corresponding down-regulated transcripts. The antisense transcripts were significantly enriched in processes related to RNA pol III transcription and the TFIIIC complex. Conclusions We demonstrate a non-random presence of Alu repeats harboring HSF sites in heat shock responsive transcripts. This presence underlies an antisense-mediated mechanism that represents a novel component of Alu and HSF involvement in the heat shock response.
Collapse
Affiliation(s)
- Rajesh Pandey
- Genomics and Molecular Medicine, Institute of Genomics and Integrative Biology, Council of Scientific and Industrial Research (CSIR-IGIB), Delhi- India
| | | | | | | |
Collapse
|
38
|
Uthup TK, Ravindran M, Bini K, Thakurdas S. Divergent DNA methylation patterns associated with abiotic stress in Hevea brasiliensis. MOLECULAR PLANT 2011; 4:996-1013. [PMID: 21705581 DOI: 10.1093/mp/ssr039] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Cytosine methylation is a fundamental epigenetic mechanism for gene-expression regulation and development in plants. Here, we report for the first time the identification of DNA methylation patterns and their putative relationship with abiotic stress in the tree crop Hevea brasiliensis (source of 99% of natural rubber in the world). Regulatory sequences of four major genes involved in the mevalonate pathway (rubber biosynthesis pathway) and one general defense-related gene of three high-yielding popular rubber clones grown at two different agroclimatic conditions were analyzed for the presence of methylation. We found several significant variations in the methylation pattern at core DNA binding motifs within all the five genes. Several consistent clone-specific and location-specific methylation patterns were identified. The differences in methylation pattern observed at certain pivotal cis-regulatory sites indicate the direct impact of stress on the genome and support the hypothesis of site-specific stress-induced DNA methylation. It is assumed that some of the methylation patterns observed may be involved in the stress-responsive mechanism in plants by which they adapt to extreme conditions. The study also provide clues towards the existence of highly divergent phenotypic characters among Hevea clones despite their very similar genetic make-up. Altogether, the observations from this study prove beyond doubt that there exist epigenetic variations in Hevea and environmental factors play a significant role in the induction of site-specific epigenetic mutations in its genome.
Collapse
Affiliation(s)
- Thomas K Uthup
- Genome Analysis Lab, Rubber Research Institute of India, Rubber Board PO, Kottayam, Kerala, 686009, India.
| | | | | | | |
Collapse
|
39
|
Zemojtel T, Kielbasa SM, Arndt PF, Behrens S, Bourque G, Vingron M. CpG deamination creates transcription factor-binding sites with high efficiency. Genome Biol Evol 2011; 3:1304-11. [PMID: 22016335 PMCID: PMC3228489 DOI: 10.1093/gbe/evr107] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The formation of new transcription factor–binding sites (TFBSs) has a major impact on the evolution of gene regulatory networks. Clearly, single nucleotide mutations arising within genomic DNA can lead to the creation of TFBSs. Are molecular processes inducing single nucleotide mutations contributing equally to the creation of TFBSs? In the human genome, a spontaneous deamination of methylated cytosine in the context of CpG dinucleotides results in the creation of thymine (C → T), and this mutation has the highest rate among all base substitutions. CpG deamination has been ascribed a role in silencing of transposons and induction of variation in regional methylation. We have previously shown that CpG deamination created thousands of p53-binding sites within genomic sequences of Alu transposons. Interestingly, we have defined a ∼30 bp region in Alu sequence, which, depending on a pattern of CpG deamination, can be converted to functional p53-, PAX-6-, and Myc-binding sites. Here, we have studied single nucleotide mutational events leading to creation of TFBSs in promoters of human genes and in genomic regions bound by such key transcription factors as Oct4, NANOG, and c-Myc. We document that CpG deamination events can create TFBSs with much higher efficiency than other types of mutational events. Our findings add a new role to CpG methylation: We propose that deamination of methylated CpGs constitutes one of the evolutionary forces acting on mutational trajectories of TFBSs formation contributing to variability in gene regulation.
Collapse
Affiliation(s)
- Tomasz Zemojtel
- Department of Computational Molecular Biology, Max Planck Institute for Molecular Genetics, Berlin, Germany.
| | | | | | | | | | | |
Collapse
|
40
|
Pandey R, Mukerji M. From 'JUNK' to Just Unexplored Noncoding Knowledge: the case of transcribed Alus. Brief Funct Genomics 2011; 10:294-311. [DOI: 10.1093/bfgp/elr029] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
|
41
|
Cui F, Sirotin MV, Zhurkin VB. Impact of Alu repeats on the evolution of human p53 binding sites. Biol Direct 2011; 6:2. [PMID: 21208455 PMCID: PMC3032802 DOI: 10.1186/1745-6150-6-2] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2010] [Accepted: 01/06/2011] [Indexed: 12/23/2022] Open
Abstract
BACKGROUND The p53 tumor suppressor protein is involved in a complicated regulatory network, mediating expression of ~1000 human genes. Recent studies have shown that many p53 in vivo binding sites (BSs) reside in transposable repeats. The relationship between these BSs and functional p53 response elements (REs) remains unknown, however. We sought to understand whether the p53 REs also reside in transposable elements and particularly in the most-abundant Alu repeats. RESULTS We have analyzed ~160 functional p53 REs identified so far and found that 24 of them occur in repeats. More than half of these repeat-associated REs reside in Alu elements. In addition, using a position weight matrix approach, we found ~400,000 potential p53 BSs in Alu elements genome-wide. Importantly, these putative BSs are located in the same regions of Alu repeats as the functional p53 REs - namely, in the vicinity of Boxes A/A' and B of the internal RNA polymerase III promoter. Earlier nucleosome-mapping experiments showed that the Boxes A/A' and B have a different chromatin environment, which is critical for the binding of p53 to DNA. Here, we compare the Alu-residing p53 sites with the corresponding Alu consensus sequences and conclude that the p53 sites likely evolved through two different mechanisms - the sites overlapping with the Boxes A/A' were generated by CG → TG mutations; the other sites apparently pre-existed in the progenitors of several Alu subfamilies, such as AluJo and AluSq. The binding affinity of p53 to the Alu-residing sites generally correlates with the age of Alu subfamilies, so that the strongest sites are embedded in the 'relatively young' Alu repeats. CONCLUSIONS The primate-specific Alu repeats play an important role in shaping the p53 regulatory network in the context of chromatin. One of the selective factors responsible for the frequent occurrence of Alu repeats in introns may be related to the p53-mediated regulation of Alu transcription, which, in turn, influences expression of the host genes.
Collapse
Affiliation(s)
- Feng Cui
- Laboratory of Cell Biology, National Cancer Institute, NIH, Bethesda, MD 20892, USA
| | - Michael V Sirotin
- Laboratory of Cell Biology, National Cancer Institute, NIH, Bethesda, MD 20892, USA
| | - Victor B Zhurkin
- Laboratory of Cell Biology, National Cancer Institute, NIH, Bethesda, MD 20892, USA
| |
Collapse
|
42
|
Bell CG, Finer S, Lindgren CM, Wilson GA, Rakyan VK, Teschendorff AE, Akan P, Stupka E, Down TA, Prokopenko I, Morison IM, Mill J, Pidsley R, Deloukas P, Frayling TM, Hattersley AT, McCarthy MI, Beck S, Hitman GA. Integrated genetic and epigenetic analysis identifies haplotype-specific methylation in the FTO type 2 diabetes and obesity susceptibility locus. PLoS One 2010; 5:e14040. [PMID: 21124985 PMCID: PMC2987816 DOI: 10.1371/journal.pone.0014040] [Citation(s) in RCA: 195] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2010] [Accepted: 10/27/2010] [Indexed: 01/04/2023] Open
Abstract
Recent multi-dimensional approaches to the study of complex disease have revealed powerful insights into how genetic and epigenetic factors may underlie their aetiopathogenesis. We examined genotype-epigenotype interactions in the context of Type 2 Diabetes (T2D), focussing on known regions of genomic susceptibility. We assayed DNA methylation in 60 females, stratified according to disease susceptibility haplotype using previously identified association loci. CpG methylation was assessed using methylated DNA immunoprecipitation on a targeted array (MeDIP-chip) and absolute methylation values were estimated using a Bayesian algorithm (BATMAN). Absolute methylation levels were quantified across LD blocks, and we identified increased DNA methylation on the FTO obesity susceptibility haplotype, tagged by the rs8050136 risk allele A (p = 9.40×10−4, permutation p = 1.0×10−3). Further analysis across the 46 kb LD block using sliding windows localised the most significant difference to be within a 7.7 kb region (p = 1.13×10−7). Sequence level analysis, followed by pyrosequencing validation, revealed that the methylation difference was driven by the co-ordinated phase of CpG-creating SNPs across the risk haplotype. This 7.7 kb region of haplotype-specific methylation (HSM), encapsulates a Highly Conserved Non-Coding Element (HCNE) that has previously been validated as a long-range enhancer, supported by the histone H3K4me1 enhancer signature. This study demonstrates that integration of Genome-Wide Association (GWA) SNP and epigenomic DNA methylation data can identify potential novel genotype-epigenotype interactions within disease-associated loci, thus providing a novel route to aid unravelling common complex diseases.
Collapse
Affiliation(s)
- Christopher G Bell
- Medical Genomics, UCL Cancer Institute, University College London, London, United Kingdom.
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
43
|
Bell CG, Beck S. The epigenomic interface between genome and environment in common complex diseases. Brief Funct Genomics 2010; 9:477-85. [PMID: 21062751 DOI: 10.1093/bfgp/elq026] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The epigenome plays the pivotal role as interface between genome and environment. True genome-wide assessments of epigenetic marks, such as DNA methylation (methylomes) or chromatin modifications (chromatinomes), are now possible, either through high-throughput arrays or increasingly by second-generation DNA sequencing methods. The ability to collect these data at this level of resolution enables us to begin to be able to propose detailed questions, and interrogate this information, with regards to changes that occur due to development, lineage and tissue-specificity, and significantly those caused by environmental influence, such as ageing, stress, diet, hormones or toxins. Common complex traits are under variable levels of genetic influence and additionally epigenetic effect. The detection of pathological epigenetic alterations will reveal additional insights into their aetiology and how possible environmental modulation of this mechanism may occur. Due to the reversibility of these marks, the potential for sequence-specific targeted therapeutics exists. This review surveys recent epigenomic advances and their current and prospective application to the study of common diseases.
Collapse
|
44
|
Belancio VP, Roy-Engel AM, Deininger PL. All y'all need to know 'bout retroelements in cancer. Semin Cancer Biol 2010; 20:200-10. [PMID: 20600922 DOI: 10.1016/j.semcancer.2010.06.001] [Citation(s) in RCA: 121] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2010] [Revised: 06/14/2010] [Accepted: 06/17/2010] [Indexed: 01/08/2023]
Abstract
Genetic instability is one of the principal hallmarks and causative factors in cancer. Human transposable elements (TE) have been reported to cause human diseases, including several types of cancer through insertional mutagenesis of genes critical for preventing or driving malignant transformation. In addition to retrotransposition-associated mutagenesis, TEs have been found to contribute even more genomic rearrangements through non-allelic homologous recombination. TEs also have the potential to generate a wide range of mutations derivation of which is difficult to directly trace to mobile elements, including double strand breaks that may trigger mutagenic genomic rearrangements. Genome-wide hypomethylation of TE promoters and significantly elevated TE expression in almost all human cancers often accompanied by the loss of critical DNA sensing and repair pathways suggests that the negative impact of mobile elements on genome stability should increase as human tumors evolve. The biological consequences of elevated retroelement expression, such as the rate of their amplification, in human cancers remain obscure, particularly, how this increase translates into disease-relevant mutations. This review is focused on the cellular mechanisms that control human TE-associated mutagenesis in cancer and summarizes the current understanding of TE contribution to genetic instability in human malignancies.
Collapse
Affiliation(s)
- Victoria P Belancio
- Tulane University, Department of Structural and Cellular Biology, School of Medicine, Tulane Cancer Center and Tulane Center for Aging, New Orleans, LA 70112, USA
| | | | | |
Collapse
|
45
|
Reid JE, Evans KJ, Dyer N, Wernisch L, Ott S. Variable structure motifs for transcription factor binding sites. BMC Genomics 2010; 11:30. [PMID: 20074339 PMCID: PMC2824720 DOI: 10.1186/1471-2164-11-30] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2009] [Accepted: 01/14/2010] [Indexed: 02/06/2023] Open
Abstract
Background Classically, models of DNA-transcription factor binding sites (TFBSs) have been based on relatively few known instances and have treated them as sites of fixed length using position weight matrices (PWMs). Various extensions to this model have been proposed, most of which take account of dependencies between the bases in the binding sites. However, some transcription factors are known to exhibit some flexibility and bind to DNA in more than one possible physical configuration. In some cases this variation is known to affect the function of binding sites. With the increasing volume of ChIP-seq data available it is now possible to investigate models that incorporate this flexibility. Previous work on variable length models has been constrained by: a focus on specific zinc finger proteins in yeast using restrictive models; a reliance on hand-crafted models for just one transcription factor at a time; and a lack of evaluation on realistically sized data sets. Results We re-analysed binding sites from the TRANSFAC database and found motivating examples where our new variable length model provides a better fit. We analysed several ChIP-seq data sets with a novel motif search algorithm and compared the results to one of the best standard PWM finders and a recently developed alternative method for finding motifs of variable structure. All the methods performed comparably in held-out cross validation tests. Known motifs of variable structure were recovered for p53, Stat5a and Stat5b. In addition our method recovered a novel generalised version of an existing PWM for Sp1 that allows for variable length binding. This motif improved classification performance. Conclusions We have presented a new gapped PWM model for variable length DNA binding sites that is not too restrictive nor over-parameterised. Our comparison with existing tools shows that on average it does not have better predictive accuracy than existing methods. However, it does provide more interpretable models of motifs of variable structure that are suitable for follow-up structural studies. To our knowledge, we are the first to apply variable length motif models to eukaryotic ChIP-seq data sets and consequently the first to show their value in this domain. The results include a novel motif for the ubiquitous transcription factor Sp1.
Collapse
Affiliation(s)
- John E Reid
- MRC Biostatistics Unit, Institute of Public Health, Forvie Site, Cambridge, CB2 0SR, UK.
| | | | | | | | | |
Collapse
|
46
|
Identification of transcription factor binding sites derived from transposable element sequences using ChIP-seq. Methods Mol Biol 2010; 674:225-40. [PMID: 20827595 DOI: 10.1007/978-1-60761-854-6_14] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Transposable elements (TEs) form a substantial fraction of the non-coding DNA of many eukaryotic genomes. There are numerous examples of TEs being exapted for regulatory function by the host, many of which were identified through their high conservation. However, given that TEs are often the youngest part of a genome and typically exhibit a high turnover, conservation-based methods will fail to identify lineage- or species-specific exaptations. ChIP-seq has become a very popular and effective method for identifying in vivo DNA-protein interactions, such as those seen at transcription factor binding sites (TFBS), and has been used to show that there are a large number of TE-derived TFBS. Many of these TE-derived TFBS show poor conservation and would go unnoticed using conservation screens. Here, we describe a simple pipeline method for using data generated through ChIP-seq to identify TE-derived TFBS.
Collapse
|
47
|
Transposable elements in gene regulation and in the evolution of vertebrate genomes. Curr Opin Genet Dev 2009; 19:607-12. [PMID: 19914058 DOI: 10.1016/j.gde.2009.10.013] [Citation(s) in RCA: 112] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2009] [Revised: 10/20/2009] [Accepted: 10/26/2009] [Indexed: 01/30/2023]
Abstract
Repetitive DNA and in particular transposable elements have been intimately linked to eukaryotic genomes for millions of years. Once overlooked for being only a collection of selfish debris and a nuisance for sequence assembly, genomic repeats are now being recognized as a key driving force in genome evolution. Indeed, by changing the DNA landscape of genomes, transposable elements have been a rich source of innovation in genes, regulatory elements and genome structures. In this review, I will focus on recent advances that demonstrate that genomic repeats have had a global impact on vertebrate gene regulatory networks. I will also summarize results that show how transposable elements have been a major catalyst of structural rearrangements throughout evolution.
Collapse
|
48
|
Chen X, El Gazzar M, Yoza BK, McCall CE. The NF-kappaB factor RelB and histone H3 lysine methyltransferase G9a directly interact to generate epigenetic silencing in endotoxin tolerance. J Biol Chem 2009; 284:27857-27865. [PMID: 19690169 DOI: 10.1074/jbc.m109.000950] [Citation(s) in RCA: 147] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
The interplay of transcription factors, histone modifiers, and DNA modification can alter chromatin structure that epigenetically controls gene transcription. During severe systemic inflammatory (SSI), the generation of facultative heterochromatin from euchromatin reversibly silences transcription of a set of acute proinflammatory genes. This gene-specific silencing is a salient feature of the endotoxin tolerant phenotype that is found in blood leukocytes of SSI patients and in a human THP-1 cell model of SSI. We previously reported that de novo induction of the NF-kappaB transcription factor RelB by endotoxin activation is necessary and sufficient for silencing transcription of acute proinflammatory genes in the endotoxin tolerant SSI phenotype. Here, we examined how RelB silences gene expression and found that RelB induces facultative heterochromatin formation by directly interacting with the histone H3 lysine 9 methyltransferase G9a. We found that heterochromatin protein 1 (HP1) and G9a formed a complex at the interleukin-1beta promoter that is dependent on the Rel homology domain (RHD) of RelB. RelB knockdown disassociated the complex and reversed transcription silencing. We also observed that whereas RelB chromatin binding was independent of G9a, RelB transcriptional silencing required G9a accumulation at the silenced promoter. Binding between RelB and G9a was confirmed by glutathione S-transferase pulldown in vitro and coimmunoprecipitation in vivo. These data provide novel insight into how RelB is required to initiate silencing in the phenotype associated with severe systemic inflammation in humans, a disease with major morbidity and mortality.
Collapse
Affiliation(s)
- Xiaoping Chen
- Department of Internal Medicine, Section of Molecular Medicine, Wake Forest University School of Medicine, Winston-Salem, North Carolina 27157
| | - Mohamed El Gazzar
- Department of Internal Medicine, Section of Molecular Medicine, Wake Forest University School of Medicine, Winston-Salem, North Carolina 27157
| | - Barbara K Yoza
- Department of Internal Medicine, Section of Molecular Medicine, Wake Forest University School of Medicine, Winston-Salem, North Carolina 27157; Department of General Surgery, Wake Forest University School of Medicine, Winston-Salem, North Carolina 27157
| | - Charles E McCall
- Department of Internal Medicine, Section of Molecular Medicine, Wake Forest University School of Medicine, Winston-Salem, North Carolina 27157.
| |
Collapse
|