Project description:Genomic DNA is isolated from C57BL6/J mice at E17.5 and postnatal d21, and we used MCAM to identify genes undergoing methylation change during late fetal to early postnatal mouse liver development.
Project description:HBV transcription and replication increases progressively throughout postnatal liver development with maximal viral biosynthesis occurring at around four weeks of age in the HBV transgenic mouse model of chronic infection. Increasing viral biosynthesis is associated with a corresponding progressive loss of DNA methylation. The loss of DNA methylation is associated with increasing levels of 5-hydroxymethylcytosine (5hmC) residues which correlates with increased liver-enriched pioneer transcription factor Forkhead box protein A (FoxA) RNA levels, a rapid decline in postnatal liver DNA methyltransferase (Dnmt) transcripts and a very modest reduction in Ten-eleven translocation (Tet) methylcytosine dioxygenase expression. These observations are consistent with the suggestion that the balance between active HBV DNA methylation and demethylation is regulated by FoxA recruitment of Tet in the presence of declining Dnmt activity. These changes lead to demethylation of the viral genome during hepatocyte maturation with associated increases in viral biosynthesis. Consequently, manipulation of the relative activities of these two counter-balancing processes might permit the specific silencing of HBV gene expression with the loss of viral biosynthesis and the resolution of chronic HBV infections.
Project description:Genomic DNA is isolated from C57BL6/J mice at E17.5 and postnatal d21, and we used MCAM to identify genes undergoing methylation change during late fetal to early postnatal mouse liver development. Two-condition experiment, P21 vs. E17.5. Biological replicates: 2 for each condition.
Project description:DNA methylation marks are thought to be set up during early development and to remain static thereafter in healthy tissues. Here, we characterize the liver DNA methylation patterns of mice before birth, during early postnatal development (from birth until weaning) and in adulthood. Our analyses show extensive epigenetic reprogramming in the liver occurring during postnatal development. 118,877 of 261,317 CpGs analyzed throughout the genome significantly changed their methylation level by more than 5% from birth to nine weeks of age, with some changing by up to 86%. Interestingly, changes in DNA methylation occur primarily in intergenic enhancer regions while gene promoters seem little affected. Analysis of 166 CpGs at multiple time points by locus-specific bisulfite sequencing reveals that this reprogramming primarily occurs between postnatal day 1 and day 20. This time period coincides with two major cellular changes in the liver: the differentiation of hepatocytes and extensive cell division. While cell multiplication leaves a distinct footprint on the DNA methylation patterns, we show that the extensive epigenetic reprogramming likely results from differentiation of hepatoblasts into hepatocytes. Overall, our data suggest that epigenetic remodeling is an important aspect of normal liver maturation and involves a large number of gene enhancers.
Project description:DNA methylation marks are thought to be set up during early development and to remain static thereafter in healthy tissues. Here, we characterize the liver DNA methylation patterns of mice before birth, during early postnatal development (from birth until weaning) and in adulthood. Our analyses show extensive epigenetic reprogramming in the liver occurring during postnatal development. 118,877 of 261,317 CpGs analyzed throughout the genome significantly changed their methylation level by more than 5% from birth to nine weeks of age, with some changing by up to 86%. Interestingly, changes in DNA methylation occur primarily in intergenic enhancer regions while gene promoters seem little affected. Analysis of 166 CpGs at multiple time points by locus-specific bisulfite sequencing reveals that this reprogramming primarily occurs between postnatal day 1 and day 20. This time period coincides with two major cellular changes in the liver: the differentiation of hepatocytes and extensive cell division. While cell multiplication leaves a distinct footprint on the DNA methylation patterns, we show that the extensive epigenetic reprogramming likely results from differentiation of hepatoblasts into hepatocytes. Overall, our data suggest that epigenetic remodeling is an important aspect of normal liver maturation and involves a large number of gene enhancers.
Project description:Adverse experiences in early life are risk factors for the development of behavioral and physiological symptoms that can lead to psychiatric and cognitive disorders later in life. Some of these symptoms can be transmitted to the offspring, in some cases by non-genomic mechanisms involving germ cells. Using a mouse model of unpredictable maternal separation and maternal stress, we show that postnatal trauma alters coping behaviors in adverse conditions in exposed males when adult and in their adult male progeny. The behavioral changes are accompanied by increased glucocorticoid receptor (GR) expression and decreased DNA methylation of the GR promoter in the hippocampus. DNA methylation is also decreased in sperm cells of exposed males when adult. Transgenerational transmission of behavioral symptoms is prevented by paternal environmental enrichment, an effect associated with the reversal of alterations in GR gene expression and DNA methylation in the hippocampus of the male offspring. These findings highlight the influence of both, negative and positive environmental factors on behavior across generations, and the plasticity of the epigenome across life.
Project description:Microarray analysis of male and female CD-1 mouse liver was carried out at 3, 4, and 8 wk of age to elucidate developmental changes in gene expression from the pre-pubertal period to young adulthood. A large number of sex-biased and sex-independent genes showed significant changes during this developmental period. Notably, sex-independent genes involved in cell cycle, chromosome condensation, and DNA replication were down regulated from 3 wk to 8 wk, while genes associated with metal ion binding, ion transport and kinase activity were up regulated. A majority of genes showing sex differential expression in adult liver did not display sex differences prior to puberty, at which time extensive changes in sex-specific gene expression were seen, primarily in males. Thus, in male liver, 76% of male-specific genes were up regulated and 47% of female-specific genes were down regulated from 3 to 8 wk of age, whereas in female liver 67% of sex-specific genes showed no significant change in expression. In both sexes, genes up regulated from 3 to 8 wk were significantly enriched (p < E-76) in the set of genes positively regulated by the liver transcription factor HNF4α, as determined in a liver-specific HNF4α knockout mouse model, while genes down regulated during this developmental period showed significant enrichment (p < E-65) for negative regulation by HNF4α. Significant enrichment of the developmentally regulated genes in genes subject to positive and negative regulation by pituitary hormone was also observed. Nine sex-specific transcription factors showed pubertal changes in expression and may contribute to the developmental changes that onset after 3-4 wk. Overall, the observed changes in gene expression during postnatal liver development reflect the deceleration of liver growth and the induction of specialized liver functions, with widespread changes in sex-specific gene expression primarily occurring in male liver.