Rewiring of chromatin state and gene expression by transposable elements

Author(s):  
Hitoshi Ohtani ◽  
Yuka W. Iwasaki
2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Julius Judd ◽  
Hayley Sanderson ◽  
Cédric Feschotte

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.


2019 ◽  
Author(s):  
Logan J. Everett ◽  
Wen Huang ◽  
Shanshan Zhou ◽  
Mary Anna Carbone ◽  
Richard F. Lyman ◽  
...  

SummaryA major challenge in modern biology is to understand how naturally occurring variation in DNA sequences affects complex organismal traits through networks of intermediate molecular phenotypes. Here, we performed deep RNA sequencing of 200 Drosophila Genetic Reference Panel inbred lines with complete genome sequences, and mapped expression quantitative trait loci for annotated genes, novel transcribed regions (most of which are long noncoding RNAs), transposable elements and microbial species. We identified host variants that affect expression of transposable elements, independent of their copy number, as well as microbiome composition. We constructed sex-specific expression quantitative trait locus regulatory networks. These networks are enriched for novel transcribed regions and target genes in heterochromatin and euchromatic regions of reduced recombination, and genes regulating transposable element expression. This study provides new insights regarding the role of natural genetic variation in regulating gene expression and generates testable hypotheses for future functional analyses.


2021 ◽  
Author(s):  
Gabriel Rech ◽  
Santiago Radio ◽  
Sara Guirao-Rico ◽  
Laura Aguilera ◽  
Vivien Horvath ◽  
...  

High quality reference genomes are crucial to understanding genome function, structure and evolution. The availability of reference genomes has allowed us to start inferring the role of genetic variation in biology, disease, and biodiversity conservation. However, analyses across organisms demonstrate that a single reference genome is not enough to capture the global genetic diversity present in populations. In this work, we generated 32 high-quality reference genomes for the well-known model species D. melanogaster and focused on the identification and analysis of transposable element variation as they are the most common type of structural variant. We showed that integrating the genetic variation across natural populations from five climatic regions increases the number of detected insertions by 58%. Moreover, 26% to 57% of the insertions identified using long-reads were missed by short-reads methods. We also identified hundreds of transposable elements associated with gene expression variation and new TE variants likely to contribute to adaptive evolution in this species. Our results highlight the importance of incorporating the genetic variation present in natural populations to genomic studies, which is essential if we are to understand how genomes function and evolve.


2018 ◽  
Vol 201 (2) ◽  
pp. 757-771 ◽  
Author(s):  
Kyu-Seon Oh ◽  
Rachel A. Gottschalk ◽  
Nicolas W. Lounsbury ◽  
Jing Sun ◽  
Michael G. Dorrington ◽  
...  

2021 ◽  
Author(s):  
Juan Manuel Crescente ◽  
Diego Zavallo ◽  
Mariana del Vas ◽  
Sebastian Asurmendi ◽  
Marcelo Helguera ◽  
...  

Abstract Plant microRNAs (miRNAs) are a class of small non-coding RNAs that are 20–24 nucleotides length and can repress gene expression at post-transcriptional levels by target degradation or translational repression. There is increasing evidence that some microRNAs can be derived from a group of non-autonomous class II transposable elements called Miniature Inverted-repeat Transposable Elements (MITEs) in plants. We used public small RNA, degradome libraries and the common wheat (Triticum aestivum) genome to screen miRNAs production and target sites. We also created a comprehensive wheat MITE database using known and identifying novel elements. We found high homology between MITEs and 14% of all the miRNAs production sites in wheat. Furthermore, we show that MITE-derived miRNAs have preference for target degradation sites with MITE insertions in 3' UTR regions in wheat.


Viruses ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 1089 ◽  
Author(s):  
Rocio Enriquez-Gasca ◽  
Poppy A. Gould ◽  
Helen M. Rowe

The human genome has been under selective pressure to evolve in response to emerging pathogens and other environmental challenges. Genome evolution includes the acquisition of new genes or new isoforms of genes and changes to gene expression patterns. One source of genome innovation is from transposable elements (TEs), which carry their own promoters, enhancers and open reading frames and can act as ‘controlling elements’ for our own genes. TEs include LINE-1 elements, which can retrotranspose intracellularly and endogenous retroviruses (ERVs) that represent remnants of past retroviral germline infections. Although once pathogens, ERVs also represent an enticing source of incoming genetic material that the host can then repurpose. ERVs and other TEs have coevolved with host genes for millions of years, which has allowed them to become embedded within essential gene expression programmes. Intriguingly, these host genes are often subject to the same epigenetic control mechanisms that evolved to combat the TEs that now regulate them. Here, we illustrate the breadth of host gene regulation through TEs by focusing on examples of young (The New), ancient (The Old), and disease-causing (The Ugly) TE integrants.


2019 ◽  
Vol 20 (22) ◽  
pp. 5755 ◽  
Author(s):  
Denise Drongitis ◽  
Francesco Aniello ◽  
Laura Fucci ◽  
Aldo Donizetti

The biology of transposable elements (TEs) is a fascinating and complex field of investigation. TEs represent a substantial fraction of many eukaryotic genomes and can influence many aspects of DNA function that range from the evolution of genetic information to duplication, stability, and gene expression. Their ability to move inside the genome has been largely recognized as a double-edged sword, as both useful and deleterious effects can result. A fundamental role has been played by the evolution of the molecular processes needed to properly control the expression of TEs. Today, we are far removed from the original reductive vision of TEs as “junk DNA”, and are more convinced that TEs represent an essential element in the regulation of gene expression. In this review, we summarize some of the more recent findings, mainly in the animal kingdom, concerning the active roles that TEs play at every level of gene expression regulation, including chromatin modification, splicing, and protein translation.


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