Project description:Background: DNA methylation is influenced by both environmental and genetic factors and is increasingly thought to affect variation in complex traits and diseases. Yet, the extent of ancestry-related differences in DNA methylation, its genetic determinants, and their respective causal impact on immune gene regulation remain elusive. Results: We report extensive population differences in DNA methylation between 156 individuals of African and Europeandescent —detected in primary monocytes that were used as a model of a major innate immunity cell type. Most of these differences (~70%) were driven by DNA sequence variants nearby CpG sites (meQTLs), which account for ~60% of the variance in DNA methylation. We also identify several master regulators of DNA methylation variation in trans, including a regulatory hub nearby the transcription factor-encoding CTCF gene, which contributes markedly to ancestry-related differences in DNA methylation. Furthermore, we establish that variationin DNA methylation isassociated with varying gene expression levelsfollowing mostly, but not exclusively, a canonical model of negative associations, particularly in enhancer regions. Specifically, we find that DNA methylation highly correlates with transcriptional activity of 811 and 230 genes, at the basal state and upon immune stimulation, respectively. Finally, using a Bayesian approach, we estimate causal mediation effects of DNA methylation on gene expression in ~20% of the studied cases, indicating that DNA methylation can play an active role in immune gene regulation. Conclusion: Using a system-level approach, our study reveals substantial ancestry-related differences in DNA methylation and provides evidence for their causal impact on immune gene regulation. Overall design: 156 Samples analyzed, 78 of African descent and 78 of European descent. Replicates are not included
Project description:The Androgen Receptor (AR) is the key-driving transcription factor in prostate cancer, tightly controlled by epigenetic regulation. To date, most epigenetic profiling has been performed in cell lines or limited tissue samples. To comprehensively study the epigenetic landscape, we complemented RNA-seq with ChIP-seq for AR and histone modification marks (H3K27ac, H3K4me3, H3K27me3) in 100 primary prostate carcinomas. Integrative molecular subtyping of the five data streams revealed three major subtypes of which two were clearly TMPRSS2-ERG dictated. Importantly, a third novel subtype was identified, with low AR chromatin binding and activity, even though the receptor was clearly expressed. While positive for neuroendocrine-hallmark genes, these tumors were copy number-neutral with low mutation burden, significantly depleted for genes characteristic of poor-outcome associated luminal B-subtype. We present a rich novel resource on transcriptional and epigenetic control in prostate cancer, revealing a tight control of gene regulation differentially dictated by AR over the three subtypes. Overall design: RNA-seq data for primary prostate carcinomas
Project description:Exposure to intrauterine heat stress during late gestation affects offspring performance into adulthood. However, underlying mechanistic links between thermal insult in fetal life and postnatal outcomes are not completely understood. Utilizing Reduced Representation Bisulfite Sequencing, this study evaluated DNA methylation of liver and mammary gland of bull calves and heifers that were gestated under maternal conditions of heat stress or cooling, i.e., in utero heat stressed (HT) vs. in utero cooled (CL). Liver samples from bull calves (CT = 5 and HT = 4) were collected at birth while mammary gland samples from heifers (CT = 3 and HT = 3) were collected during their first lactation. Overall design: Nine bull calves and six heifers gestated under maternal conditions of heat stress (HT, dams had access to shade) or cooling (CL, dams had access to shade, fans and soakers) were used for this study. Both bull calves (HT = 4 and CL = 5) and heifers (HT = 3 and CL = 3) were exposed to the maternal treatment through the intrauterine environment during the last 6-7 weeks of fetal development. Liver samples were collect from bull calves inmediately after birth. Heifers were managed under identical conditions from birth through their first lactation and mammary gland samples were collected on day 21 of the first lactation, coinciding with the rising milk yield phase of the lactation cycle. Liver and mammary gland samples were subjected to DNA extraction and subsequent reduced representation bisulfite sequencing.
Project description:MeCP2 plays a multifaceted role in gene expression regulation and chromatin organization. Interaction between MeCP2 and methylated DNA to regulate gene expression is well established. However, the widespread MeCP2 distribution suggests its additional interactions with chromatin. Here we show, by both biochemical and ChIP-seq analyses, that MeCP2 directly binds to nucleosome subunit proteins and is recruited to distinct chromatin regions where H3K27me3 is enriched. We further observed that the impact of MeCP2 on transcriptional changes is correlated with histone post-translational modification patterns. Our findings indicate that MeCP2 can be recruited to genomic loci via indirect binding and that interaction between MeCP2 and histone proteins plays a significant role in gene expression regulation. Overall design: In order to perform genome-wide quantitative comparisons of histone modification difference between DMSO and GSK343 treatment, the drosophila S2 genome was added to each experiment. An exogenous genome-derived normalizing factor was used for normalization. Please note that each processed data file was generated from both rep1 and rep2 samples, and is linked to the corresponding rep1 sample records.
Project description:Cellular heterogeneity within the mammalian brain poses a challenge towards understanding its complex functions. Within the olfactory bulb (OB), odor information is processed by subtypes of inhibitory interneurons whose heterogeneity and functionality is influenced by ongoing adult neurogenesis. To investigate this cellular heterogeneity, and to better understand the developmental programs of adult-born neurons, we utilized single cell RNA sequencing and computational modeling to reveal diverse and transcriptionally distinct neuronal and non-neuronal cell types. We also analyzed molecular changes during adult-born interneuron maturation, and uncovered developmental programs within their gene expression profiles. Finally, we discovered that distinct neuronal subtypes are differentially affected by sensory experience. Together, these data provide a transcriptome-based foundation for investigating subtype-specific neuronal function in the OB, charting the molecular profiles that arise during the maturation and integration of adult-born neurons, and documenting activity-dependent changes in the cellular composition of the olfactory system. Overall design: To develop a comprehensive profile of cellular heterogeneity within the OB, here we employed high-throughput single-cell RNA sequencing (scRNA-seq) (Zheng et al. 2017) of activity manipulated and wildtype mouse olfactory bulbs. This technique allows an in-depth categorization of single cell molecular signatures, and provides an analysis of potential developmental and activity-dependent changes that occur in adult-born neuron populations. Together, our data inform the heterogeneity of interneurons within the OB, provide a molecular blueprint of stereotyped developmental programs for OB interneurons, and reveal the transcriptional changes that govern activity-dependent circuit integration of adult-born neurons. Furthermore, our results suggest that distinct molecular mechanisms act on different subsets of adult-born neurons, driving diversity and survival of adult-born interneuron subsets in an activity-dependent manner.
Project description:The diversity and environmental distribution of the nosZ gene, which encodes the enzyme responsible for the consumption of nitrous oxide, was investigated in marine and terrestrial environments using a functional gene microarray. The microbial communities represented by the nosZ gene probes showed strong biogeographical separation, with communities from surface ocean waters and agricultural soils significantly different from each other and from those in oceanic oxygen minimum zones. Atypical nosZ genes, usually associated with incomplete denitrification pathways, were detected in all the environments, including surface ocean waters. The abundance of nosZ genes, as estimated by quantitative PCR, was highest in the agricultural soils and lowest in surface ocean waters. Overall design: Two color array (Cy3 and Cy5): the universal standard 20-mer oligo is printed to the slide with a 70-mer oligo (an archetype). Environmental DNA sequences (fluoresced with Cy3) within 15% identity of the 70-mer conjugated to a 20-mer oligo (fluoresced with Cy5) complementary to the universal standard will bind to the oligo probes on the array. Signal is the ratio of Cy3 to Cy5. Two replicate probes were printed for each archetype. Two replicate arrays were run on duplicate targets.
Project description:Dioxin and dioxin-related polychlorinated biphenyls are potent toxicants with association with developmental heart defects and congenital heart diseases. However, the underlying mechanism of their developmental toxicity is not fully understood. Further, different animals show distinct susceptibility and phenotypes after exposure, suggesting possible species-specific effects. Using a human embryonic stem cell (ESC) cardiomyocyte differentiation model, we examined the impact, susceptible window, and dosage of 2,3,7,8‑tetrachlorodibenzo‑p‑dioxin (TCDD) on human cardiac development. We showed that treatment of human ESCs with TCDD at the ESC stage inhibits cardiomyocyte differentiation, and the effect is largely mediated by the aryl hydrocarbon receptor (AHR). We further identified genes that are differentially expressed after TCDD treatment by RNA-sequencing, and genomic regions that are occupied by AHR by chromatin immunoprecipitation and high-throughput sequencing. Our results support the model that TCDD impairs human ESC cardiac differentiation by promoting AHR binding and repression of key mesoderm genes. More importantly, our study demonstrates the toxicity of dioxin in human embryonic development and uncovered a novel mechanism by which dioxin and AHR regulates lineage commitment. It also illustrates the power of ESC-based models in the systematic study of developmental toxicology. Overall design: Chromatin immunoprecipitation and sequencing was performed to discover the genomic regions that are occupied by AHR after TCDD exposure
Project description:An understanding of how heterozygous loss-of-function mutations in ASD risk genes, such as TBR1, contribute to ASD remains elusive. Conditional Tbr1 deletion during late mouse gestation in cortical layer 6 neurons (Tbr1layer6 mutants) provides novel insights into its function, including dendritic patterning, synaptogenesis, and cell intrinsic physiology. These phenotypes occur in heterozygotes, providing insights into mechanisms that may underlie ASD pathophysiology. Restoring expression of Wnt7b, largely rescues the synaptic deficit in Tbr1layer6 mutant neurons. Furthermore, Tbr1layer6 heterozygotes have increased anxiety-like behavior, a phenotype seen ASD. Integrating TBR1 ChIP-Seq and RNA-Seq data from layer 6 neurons, and activity of TBR1 bound candidate enhancers, provides evidence for how TBR1 regulates layer 6 properties. Moreover, several putative TBR1 targets are ASD risk genes, placing TBR1 in a central position both for ASD risk and for regulating transcriptional circuits that control multiple steps in layer 6 development essential for the assembly of neural circuits. Overall design: Examination of TBR1 genomic binding in P2 wildtype mouse cortex