scholarly journals Canonical and Non-canonical Genomic Imprinting in Rodents

2021 ◽  
Vol 9 ◽  
Author(s):  
Hisato Kobayashi
Keyword(s):  
Dna Methylation ◽  
Genomic Imprinting ◽  
Mouse Genome ◽  
Genetic Regulation ◽  
Imprinted Genes ◽  
Evolutionary Divergence ◽  
Chromatin Modifications ◽  
Allele Specific ◽  
Epigenetic Phenomenon ◽  
Parent Of Origin

Genomic imprinting is an epigenetic phenomenon that results in unequal expression of homologous maternal and paternal alleles. This process is initiated in the germline, and the parental epigenetic memories can be maintained following fertilization and induce further allele-specific transcription and chromatin modifications of single or multiple neighboring genes, known as imprinted genes. To date, more than 260 imprinted genes have been identified in the mouse genome, most of which are controlled by imprinted germline differentially methylated regions (gDMRs) that exhibit parent-of-origin specific DNA methylation, which is considered primary imprint. Recent studies provide evidence that a subset of gDMR-less, placenta-specific imprinted genes is controlled by maternal-derived histone modifications. To further understand DNA methylation-dependent (canonical) and -independent (non-canonical) imprints, this review summarizes the loci under the control of each type of imprinting in the mouse and compares them with the respective homologs in other rodents. Understanding epigenetic systems that differ among loci or species may provide new models for exploring genetic regulation and evolutionary divergence.

scholarly journals Parent of origin DNA methylation as a potential mechanism for genomic imprinting in bees.

2021 ◽  
Author(s):  
Hollie Marshall ◽  
Moi T Nicholas ◽  
Jelle S van Zweden ◽  
Felix Wäckers ◽  
Laura Ross ◽  
...  
Keyword(s):  
Dna Methylation ◽  
Genomic Imprinting ◽  
Bombus Terrestris ◽  
Experimental Manipulation ◽  
Whole Genome ◽  
Specific Expression ◽  
Differentially Methylated Genes ◽  
Allele Specific ◽  
Parent Of Origin ◽  
Functional Dna

Genomic imprinting is defined as parent-of-origin allele-specific expression. In order for genes to be expressed in this manner an `imprinting' mark must be present to distinguish the parental alleles within the genome. In mammals imprinted genes are primarily associated with DNA methylation. Genes exhibiting parent-of-origin expression have recently been identified in two species of Hymenoptera with functional DNA methylation systems; Apis mellifera and Bombus terrestris. We carried out whole genome bisulfite sequencing of parents and offspring from reciprocal crosses of two B. terrestris subspecies in order to identify parent-of-origin DNA methylation. We were unable to survey a large enough proportion of the genome to draw a conclusion on the presence of parent-of-origin DNA methylation however we were able to characterise the sex- and caste-specific methylomes of B. terrestris for the first time. We find males differ significantly to the two female castes, with differentially methylated genes involved in many histone modification related processes. We also analysed previously generated honeybee whole genome bisulfite data to see if genes previously identified as showing parent-of-origin DNA methylation in the honeybee show consistent allele-specific methylation in independent data sets. We have identified a core set of 12 genes in female castes which may be used for future experimental manipulation to explore the functional role of parent-of-origin DNA methylation in the honeybee. Finally, we have also identified allele-specific DNA methylation in honeybee male thorax tissue which suggests a role for DNA methylation in ploidy compensation in this species.

scholarly journals Bumblebee worker castes show differences in allele-specific DNA methylation and allele-specific expression

2020 ◽  
Author(s):  
H. Marshall ◽  
A.R.C. Jones ◽  
Z.N. Lonsdale ◽  
E.B. Mallon
Keyword(s):  
Dna Methylation ◽  
Bombus Terrestris ◽  
Imprinted Genes ◽  
Specific Expression ◽  
Allele Specific Expression ◽  
Genome Wide ◽  
Expression Bias ◽  
Allele Specific ◽  
Parent Of Origin ◽  
Worker Castes

AbstractAllele-specific expression is when one allele of a gene shows higher levels of expression compared to the other allele, in a diploid organism. Genomic imprinting is an extreme example of this, where some genes exhibit allele-specific expression in a parent-of-origin manner. Recent work has identified potentially imprinted genes in species of Hymenoptera. However, the molecular mechanism which drives this allelic expression bias remains unknown. In mammals DNA methylation is often associated with imprinted genes. DNA methylation systems have been described in species of Hymenoptera, providing a candidate imprinting mechanism. Using previously generated RNA-Seq and whole genome bisulfite sequencing from reproductive and sterile bumblebee (Bombus terrestris) workers we have identified genome-wide allele-specific expression and allele-specific DNA methylation. The majority of genes displaying allele-specific expression are common between reproductive castes and the proportion of allele-specific expression bias generally varies between colonies. We have also identified genome-wide allele-specific DNA methylation patterns in both castes. There is no significant overlap between genes showing allele-specific expression and allele-specific methylation. These results indicate that DNA methylation does not directly drive genome-wide allele-specific expression in this species. Only a small number of the genes identified may be ‘imprinted’ and it may be these genes which are associated with allele-specific DNA methylation. Future work utilising reciprocal crosses to identify parent-of-origin DNA methylation will further clarify the role of DNA methylation in parent-of-origin allele-specific expression.

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 Paternally expressed imprinted genes establish postzygotic hybridization barriers in Arabidopsis thaliana

eLife ◽  
2015 ◽  
Vol 4 ◽  
Author(s):  
Philip Wolff ◽  
Hua Jiang ◽  
Guifeng Wang ◽  
Juan Santos-González ◽  
Claudia Köhler
Keyword(s):  
Arabidopsis Thaliana ◽  
Differential Expression ◽  
Seed Development ◽  
Genomic Imprinting ◽  
Imprinted Genes ◽  
Functional Requirement ◽  
Functional Roles ◽  
Epigenetic Phenomenon ◽  
Parent Of Origin

Genomic imprinting is an epigenetic phenomenon causing parent-of-origin specific differential expression of maternally and paternally inherited alleles. While many imprinted genes have been identified in plants, the functional roles of most of them are unknown. In this study, we systematically examine the functional requirement of paternally expressed imprinted genes (PEGs) during seed development in Arabidopsis thaliana. While none of the 15 analyzed peg mutants has qualitative or quantitative abnormalities of seed development, we identify three PEGs that establish postzygotic hybridization barriers in the endosperm, revealing that PEGs have a major role as speciation genes in plants. Our work reveals that a subset of PEGs maintains functional roles in the inbreeding plant Arabidopsis that become evident upon deregulated expression.

scholarly journals Parent of origin gene expression in a founder population identifies two new imprinted genes at known imprinted regions

2018 ◽  
Author(s):  
Sahar V. Mozaffari ◽  
Michelle M. Stein ◽  
Kevin M. Magnaye ◽  
Dan L. Nicolae ◽  
Carole Ober
Keyword(s):  
Gene Expression ◽  
Dna Methylation ◽  
Gene Expression Data ◽  
Imprinted Genes ◽  
Genotype Data ◽  
Expression Data ◽  
Rna Seq ◽  
Specific Expression ◽  
Allele Specific ◽  
Parent Of Origin

AbstractGenomic imprinting is the phenomena that leads to silencing of one copy of a gene inherited from a specific parent. Mutations in imprinted regions have been involved in diseases showing parent of origin effects. Identifying genes with evidence of parent of origin expression patterns in family studies allows the detection of more subtle imprinting. Here, we use allele specific expression in lymphoblastoid cell lines from 306 Hutterites related in a single pedigree to provide formal evidence for parent of origin effects. We take advantage of phased genotype data to assign parent of origin to RNA-seq reads in individuals with gene expression data. Our approach identified known imprinted genes, two putative novel imprinted genes, and 14 genes with asymmetrical parent of origin gene expression. We used gene expression in peripheral blood leukocytes (PBL) to validate our findings, and then confirmed imprinting control regions (ICRs) using DNA methylation levels in the PBLs.Author SummaryLarge scale gene expression studies have identified known and novel imprinted genes through allele specific expression without knowing the parental origins of each allele. Here, we take advantage of phased genotype data to assign parent of origin to RNA-seq reads in 306 individuals with gene expression data. We identified known imprinted genes as well as two novel imprinted genes in lymphoblastoid cell line gene expression. We used gene expression in PBLs to validate our findings, and DNA methylation levels in PBLs to confirm previously characterized imprinting control regions that could regulate these imprinted genes.

scholarly journals Natural epigenetic polymorphisms lead to intraspecific variation in Arabidopsis gene imprinting

eLife ◽  
2014 ◽  
Vol 3 ◽  
Author(s):  
Daniela Pignatta ◽  
Robert M Erdmann ◽  
Elias Scheer ◽  
Colette L Picard ◽  
George W Bell ◽  
...  
Keyword(s):  
Gene Expression ◽  
Dna Methylation ◽  
Seed Development ◽  
Intraspecific Variation ◽  
Small Rnas ◽  
Expression Patterns ◽  
Imprinted Genes ◽  
Standing Variation ◽  
Allele Specific ◽  
Parent Of Origin

Imprinted gene expression occurs during seed development in plants and is associated with differential DNA methylation of parental alleles, particularly at proximal transposable elements (TEs). Imprinting variability could contribute to observed parent-of-origin effects on seed development. We investigated intraspecific variation in imprinting, coupled with analysis of DNA methylation and small RNAs, among three Arabidopsis strains with diverse seed phenotypes. The majority of imprinted genes were parentally biased in the same manner among all strains. However, we identified several examples of allele-specific imprinting correlated with intraspecific epigenetic variation at a TE. We successfully predicted imprinting in additional strains based on methylation variability. We conclude that there is standing variation in imprinting even in recently diverged genotypes due to intraspecific epiallelic variation. Our data demonstrate that epiallelic variation and genomic imprinting intersect to produce novel gene expression patterns in seeds.

scholarly journals Regulation of Parent-of-Origin Allelic Expression in Arabidopsis thaliana endosperm

2019 ◽  
Author(s):  
Karina S. Hornslien ◽  
Jason R. Miller ◽  
Paul E. Grini
Keyword(s):  
Dna Methylation ◽  
High Resolution ◽  
Epigenetic Regulation ◽  
High Throughput Sequencing ◽  
Imprinted Genes ◽  
Sequencing Data ◽  
Plant Seed ◽  
Gene Copies ◽  
Epigenetic Phenomenon ◽  
Parent Of Origin

AbstractGenomic imprinting is an epigenetic phenomenon set in the gametes prior to fertilization that causes differential expression of parental alleles mainly in the endosperm of flowering plants. The overlap between previously identified panels of imprinted genes is limited. In order to achieve high resolution sequencing data we have used sequence capture technology to investigate imprinting. Here, we present a bioinformatics pipeline to assay parent-of-origin allele specific expression and report more than 300 loci with parental expression bias. We find that the level of expression from maternal and paternal alleles in most cases is not binary, instead favouring a differential dosage hypothesis for the evolution of imprinting in plants. To address imprinting regulation, we systematically employed mutations in regulative epigenetic pathways suggested to be major players in the process. We establish the mechanistic mode of imprinting for more than 50 loci regulated by DNA methylation and Polycomb-dependent histone methylation. However, the imprinting patterns of the majority of genes were not affected by these mechanisms. To this end we also demonstrate that the RNA-directed DNA methylation pathway alone does not influence imprinting patterns in a substantial manner, suggesting more complex epigenetic regulation pathways for the majority of identified imprinted genes.Author summaryExpression of gene copies only from the mother or the father’s genome, also termed imprinting, is a specialized epigenetic phenomenon that is found to be enriched at some genes expressed in the mammalian placenta and in the endosperm of the plant seed. Although several studies have reported on imprinted genes in plants, the identified loci are at large non-overlapping between reports. This motivated us to investigate in detail the expression pattern of imprinted genes in the endosperm and to determine how imprinting patterns are established at various imprinted loci. Although several underlying epigenetic regulation mechanisms have been demonstrated to establish imprinting patterns at certain genes, the majority of imprinted genes have not been linked to such mechanisms. In the present study we systematically investigated the mechanisms that are involved in establishing imprinting, by employing mutants of epigenetic regulators and high-throughput sequencing. In our high resolution study, we report more than 300 imprinted genes and demonstrate that the biological phenomenon imprinting involves gradual expression of parental gene copies rather than switching gene copies on or off. Notably, for the majority of imprinted genes, the mechanisms previously believed to be major to establish their imprinting patterns, are not responsible for mediating imprinting.

scholarly journals Genomic imprinting in germ cells: imprints are under control

Reproduction ◽  
2010 ◽  
Vol 140 (3) ◽  
pp. 411-423 ◽  
Author(s):  
Philippe Arnaud
Keyword(s):  
Dna Methylation ◽  
Genomic Imprinting ◽  
Germ Cells ◽  
Imprinted Genes ◽  
Regulatory Sequences ◽  
Sequence Specificity ◽  
Maternal Allele ◽  
Primary Sequence ◽  
Chromatin Configuration

The cis-acting regulatory sequences of imprinted gene loci, called imprinting control regions (ICRs), acquire specific imprint marks in germ cells, including DNA methylation. These epigenetic imprints ensure that imprinted genes are expressed exclusively from either the paternal or the maternal allele in offspring. The last few years have witnessed a rapid increase in studies on how and when ICRs become marked by and subsequently maintain such epigenetic modifications. These novel findings are summarised in this review, which focuses on the germline acquisition of DNA methylation imprints and particularly on the combined role of primary sequence specificity, chromatin configuration, non-histone proteins and transcriptional events.

scholarly journals ZFP57 dictates allelic expression switch of target imprinted genes

2021 ◽  
Vol 118 (5) ◽  
pp. e2005377118
Author(s):  
Weijun Jiang ◽  
Jiajia Shi ◽  
Jingjie Zhao ◽  
Qiu Wang ◽  
Dan Cong ◽  
...  
Keyword(s):  
Dna Methylation ◽  
Notch Signaling ◽  
Notch Pathway ◽  
Notch Signaling Pathway ◽  
Mouse Embryos ◽  
The Other ◽  
Allelic Expression ◽  
Monoallelic Expression ◽  
Imprinted Genes ◽  
Parent Of Origin

ZFP57 is a master regulator of genomic imprinting. It has both maternal and zygotic functions that are partially redundant in maintaining DNA methylation at some imprinting control regions (ICRs). In this study, we found that DNA methylation was lost at most known ICRs in Zfp57 mutant embryos. Furthermore, loss of ZFP57 caused loss of parent-of-origin–dependent monoallelic expression of the target imprinted genes. The allelic expression switch occurred in the ZFP57 target imprinted genes upon loss of differential DNA methylation at the ICRs in Zfp57 mutant embryos. Specifically, upon loss of ZFP57, the alleles of the imprinted genes located on the same chromosome with the originally methylated ICR switched their expression to mimic their counterparts on the other chromosome with unmethylated ICR. Consistent with our previous study, ZFP57 could regulate the NOTCH signaling pathway in mouse embryos by impacting allelic expression of a few regulators in the NOTCH pathway. In addition, the imprinted Dlk1 gene that has been implicated in the NOTCH pathway was significantly down-regulated in Zfp57 mutant embryos. Our allelic expression switch models apply to the examined target imprinted genes controlled by either maternally or paternally methylated ICRs. Our results support the view that ZFP57 controls imprinted expression of its target imprinted genes primarily through maintaining differential DNA methylation at the ICRs.

Imprinting analysis in the Acrodysplasia region of mouse chromosome 12

2009 ◽  
Vol 30 (2) ◽  
pp. 119-124 ◽  
Author(s):  
Erin N. McMurray ◽  
Eric D. Rogers ◽  
Jennifer V. Schmidt
Keyword(s):  
Mouse Chromosome ◽  
Genomic Imprinting ◽  
Critical Region ◽  
The Other ◽  
Chromosome 12 ◽  
Imprinted Genes ◽  
Skeletal Abnormalities ◽  
Mouse Mutation ◽  
Parent Of Origin

The insertional mouse mutation Adp (Acrodysplasia) confers a parent-of-origin developmental phenotype, with animals inheriting the mutation from their father showing skeletal abnormalities, whereas those inheriting the mutation from their mother are normal. This parental-specific phenotype, along with mapping of the insertion to a region of chromosome 12 proposed to contain imprinted genes, suggested that disruption of genomic imprinting might underlie the Adp phenotype. Genomic imprinting is the process by which autosomal genes are epigenetically silenced on one of the two parental alleles; imprinting mutation phenotypes manifest after inheritance from one parent but not the other. Imprinted genes typically occur in dense clusters that contain few non-imprinted genes and therefore representative genes from the Adp critical region could be assayed to identify any imprinted domains. None of the genes analysed were found to be imprinted, however, suggesting that other explanations for the Adp phenotype must be considered.

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