Project description:The role that gamete-inherited chromatin states serve in regulating gene expression across generations is poorly understood. To interrogate how histone marks inherited on parental genomes influence gene expression in offspring, we profiled different tissue contexts in worms that inherited the sperm genome lacking the repressive mark H3K27me3. We found that worms that inherited the sperm genome lacking H3K27me3 upregulated genes in all tissues profiled, which included hermaphrodite and male germlines and mixed soma. We found that most upregulated genes were upregulated specifically from sperm alleles and in a tissue-specific manner, highlighting the importance of cellular context in determining which genes are sensitive to upregulation when H3K27me3 repression is absent. To determine whether chromatin states can impact gene expression transgenerationally, i.e. across 3 generations, we profiled gene expression and chromatin states in the germlines of worms that inherited the sperm genome lacking H3K27me3 (F1 generation) and in the germlines of their offspring (F2 generation). We found that genes upregulated in F1 germlines maintained the H3K27me3(-) state of sperm alleles and that the upregulated and H3K27me3(-) state of sperm alleles was maintained in the germlines of their offspring (F2 generation). These findings demonstrate that histone marks can serve as a transgenerational carrier.
Project description:A father’s lifetime experiences can be transmitted to his offspring to affect health and development. The mechanisms underlying paternal epigenetic transmission are unclear. Unlike somatic cells, there are few nucleosomes in sperm and their function in epigenetic inheritance is unknown. We generated transgenic mice in which overexpression of the histone H3 lysine 4 (H3K4) demethylase LSD1/KDM1A during spermatogenesis reduced H3K4 dimethylation in sperm. KDM1A overexpression in one generation severely impaired development and survivability of offspring. These defects persisted transgenerationally in the absence of KDM1A germ line expression and were associated with altered RNA profiles in sperm and offspring. We show that epigenetic inheritance of aberrant development can be initiated by histone demethylase activity in developing sperm, without changes to DNA methylation at CpG-rich regions.
Project description:The host-microbiota relationship has evolved to shape mammalian physiology, including immunity, metabolism, and development. Germ-free models are widely used to study microbial effects on host processes such as immunity. Here, we find that both germ-free and T cell-deficient mice exhibit a robust sebum secretion defect persisting across multiple generations despite microbial colonization and T cell repletion. These phenotypes are inherited by progeny conceived during in vitro fertilization using germ-free sperm and eggs, demonstrating that non-genetic information in the gametes is required for microbial-dependent phenotypic transmission. Accordingly, gene expression in early embryos derived from gametes from germ-free or T-cell deficient mice are strikingly and similarly altered. Our findings demonstrate that microbial and immune-dependent regulation of non-genetic information in the gametes can transmit inherited phenotypes transgenerationally in mice. This mechanism could rapidly generate phenotypic diversity to enhance host adaptation to environmental perturbations.
Project description:A father’s lifetime experiences can be transmitted to his offspring to affect health and development. The mechanisms underlying paternal epigenetic transmission are unclear. Unlike somatic cells, there are few nucleosomes in sperm and their function in epigenetic inheritance is unknown. We generated transgenic mice in which overexpression of the histone H3 lysine 4 (H3K4) demethylase LSD1/KDM1A during spermatogenesis reduced H3K4 dimethylation in sperm. KDM1A overexpression in one generation severely impaired development and survivability of offspring. These defects persisted transgenerationally in the absence of KDM1A germ line expression and were associated with altered RNA profiles in sperm and offspring. We show that epigenetic inheritance of aberrant development can be initiated by histone demethylase activity in developing sperm, without changes to DNA methylation at CpG-rich regions.
Project description:It is unknown whether the activity of the nervous system can be inherited. In Caenorhabditis elegans nematodes, parental responses can transmit heritable small RNAs that regulate gene expression transgenerationally. In this study we show that a neuronal process can impact the next generations. Neurons-specific synthesis of RDE-4-dependent small RNAs regulates germline amplified endogenous siRNAs and germline gene expression for multiple generations. Further, the production of small RNAs in neurons controls the chemotaxis behavior of the progeny for at least three generations via the germline Argonaute HRDE-1. Among the targets of these small RNAs we identified the conserved gene saeg-2, which is transgenerationally downregulated in the germline. Silencing of saeg-2 following neuronal small RNA biogenesis is required for chemotaxis under stress. Thus, we propose a small RNA-based mechanism for communication of neuronal processes transgenerationally.
Project description:This research uses consecutive generations of two independent mutation accumulation (MA) lines in model organism A. thaliana to understand transgenerational stability of epialleles via self-fertilization. With whole-genome bisulfite sequencing, regions of instability were identified and quantified. The vast majority of the methylated genome is stably inherited to offspring and the identified unstable regions do not change frequently between generations. Additionally, an epigenetic cross of two MA lines was created to understand inheritance patterns of epialleles via outcrossing in the absence of genetic variation. Whole-genome bisulfite sequencing was used to predict epigenotype of the offspring without single nucleotide polymorphisms. In regions of differential methylation between the parents, about half of regions show predictable inheritance.
Project description:Impaired DNA replication is a hallmark of cancer and a cause of genomic instability. We report that, in addition to causing genetic change, impaired DNA replication during embryonic development can have major epigenetic consequences for a genome. In a genome-wide screen, we identified impaired DNA replication as causing increased expression from a repressed transgene in Caenorhabditis elegans. The acquired expression state behaved as an “epiallele,” being inherited for multiple generations before fully resetting. Derepression was not restricted to the transgene but was caused by a global reduction in heterochromatin-associated histone modifications due to the impaired retention of modified histones on DNA during replication in the early embryo. Impaired DNA replication during development can therefore globally derepress chromatin, creating new intergenerationally inherited epigenetic expression states.
Project description:We used chromatin immunoprecipitation followed by next-generation sequencing (ChIP-seq) to investigate the global ASHM profiles of trimethylation on histone H3 lysine 27 (H3K27me3) and histone H3 lysine 36 (H3K36me3) in two rice F1 hybrids. A total of 522 to 550 allele-specific H3K27me3 genes and 428 to 494 allele-specific H3K36me3 genes were detected in GL×93-11 and GL×TQ, accounting for 11.09% and 26.13% of the total analyzed genes, respectively. The epialleles between parents were highly related to ASHMs. Further analysis indicated that 52.48% to 70.40% of the epialleles were faithfully inherited by the F1 hybrid and contributed to 33.18% to 46.55% of the ASHM genes. Importantly, 66.67% to 82.69% of monoallelic expression genes contained the H3K36me3 modification. Further studies demonstrated a significant positive correlation of ASE with allele-specific H3K36me3 but not with H3K27me3, indicating that ASHM-H3K36me3 primarily regulates ASE in this study.