scholarly journals Concerted genomic and epigenomic changes accompany stabilization of Arabidopsis allopolyploids

2021 ◽  
Vol 5 (10) ◽  
pp. 1382-1393
Author(s):  
Xinyu Jiang ◽  
Qingxin Song ◽  
Wenxue Ye ◽  
Z. Jeffrey Chen
Keyword(s):  
Gene Expression ◽  
Dna Methylation ◽  
Small Rnas ◽  
Structural Variation ◽  
Self Incompatibility ◽  
Polyploid Evolution ◽  
Genomic Variations ◽  
Conserved Gene ◽  
Arabidopsis Suecica ◽  
Affect Gene Expression

AbstractDuring evolution successful allopolyploids must overcome ‘genome shock’ between hybridizing species but the underlying process remains elusive. Here, we report concerted genomic and epigenomic changes in resynthesized and natural Arabidopsis suecica (TTAA) allotetraploids derived from Arabidopsisthaliana (TT) and Arabidopsisarenosa (AA). A. suecica shows conserved gene synteny and content with more gene family gain and loss in the A and T subgenomes than respective progenitors, although A. arenosa-derived subgenome has more structural variation and transposon distributions than A. thaliana-derived subgenome. These balanced genomic variations are accompanied by pervasive convergent and concerted changes in DNA methylation and gene expression among allotetraploids. The A subgenome is hypomethylated rapidly from F1 to resynthesized allotetraploids and convergently to the T-subgenome level in natural A. suecica, despite many other methylated loci being inherited from F1 to all allotetraploids. These changes in DNA methylation, including small RNAs, in allotetraploids may affect gene expression and phenotypic variation, including flowering, silencing of self-incompatibility and upregulation of meiosis- and mitosis-related genes. In conclusion, concerted genomic and epigenomic changes may improve stability and adaptation during polyploid evolution.

scholarly journals Nurse cell-derived small RNAs define paternal epigenetic inheritance in Arabidopsis

2021 ◽  
Author(s):  
Jincheng Long ◽  
James Walker ◽  
Wenjing She ◽  
Billy Aldridge ◽  
Hongbo Gao ◽  
...  
Keyword(s):  
Gene Expression ◽  
Dna Methylation ◽  
Small Rnas ◽  
Nurse Cell ◽  
De Novo ◽  
Epigenetic Inheritance ◽  
Genome Integrity ◽  
Nurse Cells ◽  
Male Germline ◽  
Methylation Patterns

AbstractThe plant male germline undergoes DNA methylation reprogramming, which methylates genes de novo and thereby alters gene expression and facilitates meiosis. Why reprogramming is limited to the germline and how specific genes are chosen is unknown. Here, we demonstrate that genic methylation in the male germline, from meiocytes to sperm, is established by germline-specific siRNAs transcribed from transposons with imperfect sequence homology. These siRNAs are synthesized by meiocyte nurse cells (tapetum) via activity of the tapetum-specific chromatin remodeler CLASSY3. Remarkably, tapetal siRNAs govern germline methylation throughout the genome, including the inherited methylation patterns in sperm. Finally, we demonstrate that these nurse cell-derived siRNAs (niRNAs) silence germline transposons, thereby safeguarding genome integrity. Our results reveal that tapetal niRNAs are sufficient to reconstitute germline methylation patterns and drive extensive, functional methylation reprogramming analogous to piRNA-mediated reprogramming in animal germlines.

scholarly journals Silencing of Mutator Elements in Maize Involves Distinct Populations of Small RNAs and Distinct Patterns of DNA Methylation

Genetics ◽  
2020 ◽  
Vol 215 (2) ◽  
pp. 379-391 ◽  
Author(s):  
Diane Burgess ◽  
Hong Li ◽  
Meixia Zhao ◽  
Sang Yeol Kim ◽  
Damon Lisch
Keyword(s):  
Gene Expression ◽  
Dna Methylation ◽  
Small Rnas ◽  
Cytosine Methylation ◽  
De Novo ◽  
Epigenetic Silencing ◽  
Inverted Repeats ◽  
Causal Relationships ◽  
Terminal Inverted Repeats ◽  
Silencing Pathways

Transposable elements (TEs) are a ubiquitous feature of plant genomes. Because of the threat they post to genome integrity, most TEs are epigenetically silenced. However, even closely related plant species often have dramatically different populations of TEs, suggesting periodic rounds of activity and silencing. Here, we show that the process of de novo methylation of an active element in maize involves two distinct pathways, one of which is directly implicated in causing epigenetic silencing and one of which is the result of that silencing. Epigenetic changes involve changes in gene expression that can be heritably transmitted to daughter cells in the absence of changes in DNA sequence. Epigenetics has been implicated in phenomena as diverse as development, stress response, and carcinogenesis. A significant challenge facing those interested in investigating epigenetic phenomena is determining causal relationships between DNA methylation, specific classes of small RNAs, and associated changes in gene expression. Because they are the primary targets of epigenetic silencing in plants and, when active, are often targeted for de novo silencing, TEs represent a valuable source of information about these relationships. We use a naturally occurring system in which a single TE can be heritably silenced by a single derivative of that TE. By using this system it is possible to unravel causal relationships between different size classes of small RNAs, patterns of DNA methylation, and heritable silencing. Here, we show that the long terminal inverted repeats within Zea mays MuDR transposons are targeted by distinct classes of small RNAs during epigenetic silencing that are dependent on distinct silencing pathways, only one of which is associated with transcriptional silencing of the transposon. Further, these small RNAs target distinct regions of the terminal inverted repeats, resulting in different patterns of cytosine methylation with different functional consequences with respect to epigenetic silencing and the heritability of that silencing.

scholarly journals The Role of Aberrant DNA Methylation in Misregulation of Gene Expression in Gonadotroph Nonfunctioning Pituitary Tumors

Cancers ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 1650 ◽  
Author(s):  
Paulina Kober ◽  
Joanna Boresowicz ◽  
Natalia Rusetska ◽  
Maria Maksymowicz ◽  
Agnieszka Paziewska ◽  
...  
Keyword(s):  
Gene Expression ◽  
Dna Methylation ◽  
Pituitary Tumors ◽  
Aberrant Methylation ◽  
Qrt Pcr ◽  
Open Sea ◽  
Aberrant Dna Methylation ◽  
Positive Correlations ◽  
Affect Gene Expression

Gonadotroph nonfunctioning pituitary adenomas (NFPAs) are common intracranial tumors, but the role of aberrant epigenetic regulation in their development remains poorly understood. In this study, we investigated the effect of impaired CpG methylation in NFPAs. We determined DNA methylation and transcriptomic profiles in 32 NFPAs and normal pituitary sections using methylation arrays and sequencing, respectively. Ten percent of differentially methylated CpGs were correlated with gene expression, and the affected genes are involved in a variety of tumorigenesis-related pathways. Different proportions of gene body and promoter region localization were observed in CpGs with negative and positive correlations between methylation and gene expression, and different proportions of CpGs were located in ‘open sea’ and ‘shelf/shore’ regions. The expression of ~8% of genes differentially expressed in NFPAs was related to aberrant methylation. Methylation levels of seven CpGs located in the regulatory regions of FAM163A, HIF3A and PRSS8 were determined by pyrosequencing, and gene expression was measured by qRT-PCR and immunohistochemistry in 83 independent NFPAs. The results clearly confirmed the negative correlation between methylation and gene expression for these genes. By identifying which aberrantly methylated CpGs affect gene expression in gonadotrophinomas, our data confirm the role of aberrant methylation in pathogenesis of gonadotroph NFPAs.

scholarly journals MicroRNAs, epigenetics and disease

2010 ◽  
Vol 48 ◽  
pp. 165-185 ◽  
Author(s):  
Asli Silahtaroglu ◽  
Jan Stenvang
Keyword(s):  
Gene Expression ◽  
Dna Methylation ◽  
Histone Modifications ◽  
Target Genes ◽  
Regulation Of Gene Expression ◽  
Specific Gene ◽  
Rna Molecules ◽  
Normal Differentiation ◽  
Affect Gene Expression ◽  
Epigenetic Processes

Epigenetics is defined as the heritable chances that affect gene expression without changing the DNA sequence. Epigenetic regulation of gene expression can be through different mechanisms such as DNA methylation, histone modifications and nucleosome positioning. MicroRNAs are short RNA molecules which do not code for a protein but have a role in post-transcriptional silencing of multiple target genes by binding to their 3′ UTRs (untranslated regions). Both epigenetic mechanisms, such as DNA methylation and histone modifications, and the microRNAs are crucial for normal differentiation, development and maintenance of tissue-specific gene expression. These mechanisms also explain how cells with the same DNA content can differentiate into cells with different functions. Changes in epigenetic processes can lead to changes in gene function, cancer formation and progression, as well as other diseases. In the present chapter we will mainly focus on microRNAs and methylation and their implications in human disease, mainly in cancer.

Plant simple sequence repeats: distribution, variation, and effects on gene expression

Genome ◽  
2008 ◽  
Vol 51 (2) ◽  
pp. 79-90 ◽  
Author(s):  
Natalya Sharopova
Keyword(s):  
Gene Expression ◽  
Dna Methylation ◽  
Simple Sequence Repeat ◽  
Expression Data ◽  
Sequence Repeat ◽  
Level Control ◽  
Functional Annotations ◽  
Genome Wide ◽  
Affect Gene Expression ◽  
Simple Sequence

Genome-wide simple sequence repeat (SSR) information was analyzed together with functional annotations of Arabidopsis genes and public gene expression data for Arabidopsis and rice. Analysis of more than 15 000 Arabidopsis and more than 16 000 rice SSRs indicated that SSRs may affect the expression of hundreds of genes. Data from experiments on DNA methylation, histone acetylation, and transcript turnover suggest that SSRs may affect gene expression at transcriptional and posttranscriptional levels. Members of some functional groups were shown to be enriched with SSRs and often contained similar but non-homologous repeats within the same gene regions. In addition, the distribution of perfect and imperfect SSRs in some Arabidopsis, maize, and rice genes was used to demonstrate how two-level control of SSR variation may contribute to protein evolution.

scholarly journals Dynamic and reversible DNA methylation changes induced by genome separation and merger of polyploid wheat

BMC Biology ◽  
2020 ◽  
Vol 18 (1) ◽  
Author(s):  
Jingya Yuan ◽  
Wu Jiao ◽  
Yanfeng Liu ◽  
Wenxue Ye ◽  
Xiue Wang ◽  
...  
Keyword(s):  
Gene Expression ◽  
Dna Methylation ◽  
Hexaploid Wheat ◽  
Genetic Model ◽  
Tetraploid Wheat ◽  
Epigenetic Changes ◽  
Wheat Evolution ◽  
D Genome ◽  
Polyploid Evolution ◽  
Genome Separation

Abstract Background Wheat is a powerful genetic model for studying polyploid evolution and crop domestication. Hexaploid bread wheat was formed by two rounds of interspecific hybridization and polyploidization, processes which are often accompanied by genetic and epigenetic changes, including DNA methylation. However, the extent and effect of such changes during wheat evolution, particularly from tetraploid-to-hexaploid wheat, are currently elusive. Results Here we report genome-wide DNA methylation landscapes in extracted tetraploid wheat (ETW, AABB), natural hexaploid wheat (NHW, AABBDD), resynthesized hexaploid wheat (RHW, AABBDD), natural tetraploid wheat (NTW, AABB), and diploid (DD). In the endosperm, levels of DNA methylation, especially in CHG (H=A, T, or C) context, were dramatically decreased in the ETW relative to natural hexaploid wheat; hypo-differentially methylated regions (DMRs) (850,832) were 24-fold more than hyper-DMRs (35,111). Interestingly, those demethylated regions in ETW were remethylated in the resynthesized hexaploid wheat after the addition of the D genome. In ETW, hypo-DMRs correlated with gene expression, and TEs were demethylated and activated, which could be silenced in the hexaploid wheat. In NHW, groups of TEs were dispersed in genic regions of three subgenomes, which may regulate the expression of TE-associated genes. Further, hypo-DMRs in ETW were associated with reduced H3K9me2 levels and increased expression of histone variant genes, suggesting concerted epigenetic changes after separation from the hexaploid. Conclusion Genome merger and separation provoke dynamic and reversible changes in chromatin and DNA methylation. These changes correlate with altered gene expression and TE activity, which may provide insights into polyploid genome and wheat evolution.

scholarly journals Divergence among rice cultivars reveals roles for transposition and epimutation in ongoing evolution of genomic imprinting

2021 ◽  
Vol 118 (29) ◽  
pp. e2104445118
Author(s):  
Jessica A. Rodrigues ◽  
Ping-Hung Hsieh ◽  
Deling Ruan ◽  
Toshiro Nishimura ◽  
Manoj K. Sharma ◽  
...  
Keyword(s):  
Gene Expression ◽  
Dna Methylation ◽  
Genomic Imprinting ◽  
Small Rnas ◽  
Imprinted Genes ◽  
Dna Hypomethylation ◽  
Transcription Start ◽  
Specific Expression ◽  
Parent Of Origin

Parent-of-origin–dependent gene expression in mammals and flowering plants results from differing chromatin imprints (genomic imprinting) between maternally and paternally inherited alleles. Imprinted gene expression in the endosperm of seeds is associated with localized hypomethylation of maternally but not paternally inherited DNA, with certain small RNAs also displaying parent-of-origin–specific expression. To understand the evolution of imprinting mechanisms in Oryza sativa (rice), we analyzed imprinting divergence among four cultivars that span both japonica and indica subspecies: Nipponbare, Kitaake, 93-11, and IR64. Most imprinted genes are imprinted across cultivars and enriched for functions in chromatin and transcriptional regulation, development, and signaling. However, 4 to 11% of imprinted genes display divergent imprinting. Analyses of DNA methylation and small RNAs revealed that endosperm-specific 24-nt small RNA–producing loci show weak RNA-directed DNA methylation, frequently overlap genes, and are imprinted four times more often than genes. However, imprinting divergence most often correlated with local DNA methylation epimutations (9 of 17 assessable loci), which were largely stable within subspecies. Small insertion/deletion events and transposable element insertions accompanied 4 of the 9 locally epimutated loci and associated with imprinting divergence at another 4 of the remaining 8 loci. Correlating epigenetic and genetic variation occurred at key regulatory regions—the promoter and transcription start site of maternally biased genes, and the promoter and gene body of paternally biased genes. Our results reinforce models for the role of maternal-specific DNA hypomethylation in imprinting of both maternally and paternally biased genes, and highlight the role of transposition and epimutation in rice imprinting evolution.

scholarly journals Silencing of Mu elements in maize involves distinct populations of small RNAs and distinct patterns of DNA methylation

2020 ◽  
Author(s):  
Diane Burgess ◽  
Meixia Zhao ◽  
Sang Yeol Kim ◽  
Damon Lisch
Keyword(s):  
Gene Expression ◽  
Dna Methylation ◽  
Small Rnas ◽  
Cytosine Methylation ◽  
De Novo ◽  
Epigenetic Silencing ◽  
Causal Relationships ◽  
Daughter Cells ◽  
Functional Consequences ◽  
Silencing Pathways

Epigenetic changes involve changes in gene expression that can be heritably transmitted to daughter cells in the absence of changes in DNA sequence. Epigenetics has been implicated in phenomena as diverse as development, stress response and carcinogenesis. A significant challenge facing those interested in investigating epigenetic phenomena is determining causal relationships between DNA methylation, specific classes of small RNAs and associated changes in gene expression. Because they are the primary targets of epigenetic silencing in plants and, when active, are often targeted for de novo silencing, transposable elements (TEs) represent a valuable source of information about these relationships. We use a naturally occurring system in which a single TE can be heritably silenced by a single derivative of that TE. By using this system it is possible to unravel causal relationships between different size classes of small RNAs, patterns of DNA methylation and heritable silencing. Here, we show that the long terminal inverted repeats (TIRs) within Zea mays MuDR transposons are targeted by distinct classes of small RNAs during epigenetic silencing that are dependent on distinct silencing pathways. Further, these small RNAs target distinct regions of the TIRs, resulting in different patterns of cytosine methylation with different functional consequences with respect to epigenetic silencing and heritability of that silencing.

scholarly journals From DNA to a human: What the ENCODE and Roadmap Epigenome Projects can teach us about how we are who we are

2015 ◽  
Vol 37 (5) ◽  
pp. 24-29
Author(s):  
Rebecca F. Lowdon ◽  
Devjanee Swain-Lenz
Keyword(s):  
Gene Expression ◽  
Dna Methylation ◽  
Human Genome ◽  
Genome Sequence ◽  
Human Body ◽  
Chemical Modifications ◽  
Encode Project ◽  
Amount Of Information ◽  
Fully Functioning ◽  
Affect Gene Expression

The assembly of the human genome sequence revealed that there are 3.2 billion bases in our genome, but what was less clear at the time was how this vast amount of information was organised and expressed to ensure that a single-celled zygote was able to develop into a fully functioning human body. The ENCODE project began the quest to identify and assign function to different elements within the genome and the Roadmap Epigenome Project has continued this journey by mapping chemical modifications such as DNA methylation, which are known to affect gene expression. Understanding these elements and processes in greater depth will allow us to learn more about how we became who we are and what differentiates humans from other animals.

Through a generation darkly: small RNAs in the gametophyte

2010 ◽  
Vol 38 (2) ◽  
pp. 617-621 ◽  
Author(s):  
Robert T. Grant-Downton
Keyword(s):  
Gene Expression ◽  
Dna Methylation ◽  
Small Rnas ◽  
Recent Progress ◽  
Regulation Of Gene Expression ◽  
Non Coding Rnas ◽  
And Function

The various classes of small non-coding RNAs are a fundamentally important component of the transcriptome. These molecules have roles in many essential processes such as regulation of gene expression at the transcriptional and post-transcriptional levels, guidance of DNA methylation and defence against selfish replicators such as transposons. Their diversity and functions in the sporophytic generation of angiosperms is well explored compared with the gametophytic generation, where little is known about them. Recent progress in understanding their abundance, diversity and function in the gametophyte is reviewed.

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