Project description:We assayed CpG methylation in cerebral cortex of neurologically and psychiatrically normal human postmortem specimens, as well as mouse forebrain specimens. Cross-species human-mouse DNA methylation conservation analysis shows that DNA methylation is not correlated with sequence conservation. Instead, greater DNA methylation conservation is correlated with increasing CpG density. We identified key genomic features that can be targeted for identification of epigenetic loci that may be developmentally and evolutionarily conserved and wherein aberrations in DNA methylation patterns can confer risk for disease. Characterization of evolutionary signatures of DNA methylation in the brain
Project description:What methylation changes are occurring in different compartments of early maturation stage seed largely remains unknown. To uncover the possible role of DNA methylation in different compartments of early maturation stage seed, we characterized the methylome of two major compartments in embryonic cotyledon: cotyledon abaxial parenchyma (EM-COT-ABPY) and cotyledon adaxial parenchyma (EM-COT-ADPY) using Illumina sequencing. Illumina sequencing of bisulfite-converted genomic DNA from cotyledon abaxial parenchyma (EM-COT-ABPY) and cotyledon adaxial parenchyma (EM-COT-ADPY) compartments.
Project description:Enhancers can regulate the transcription of genes over long genomic distances. This is thought to lead to selection against genomic rearrangements within such regions that may disrupt this functional linkage. We tested this concept experimentally using the human X chromosome. We describe a scoring method to identify evolutionary maintenance of linkage between conserved non-coding elements and neighbouring genes. Chromatin marks associated with enhancer function are strongly correlated with the linkage score. We tested more than 1,000 putative enhancers by transgenesis assays in zebrafish to ascertain the identity of the target gene, with a focus on genes involved in X-linked intellectual disabilities (ID). The majority of active enhancers drive a transgenic expression in a pattern consistent with the known expression of a linked gene. These results show that evolutionary maintenance of linkage is a reliable predictor of an enhancer's function, and provide new information to discover the genetic basis of diseases caused by the mis-regulation of gene expression.
Project description:Enhancers can regulate the transcription of genes over long genomic distances. This is thought to lead to selection against genomic rearrangements within such regions that may disrupt this functional linkage. We tested this concept experimentally using the human X chromosome. We describe a scoring method to identify evolutionary maintenance of linkage between conserved non-coding elements and neighbouring genes. Chromatin marks associated with enhancer function are strongly correlated with the linkage score. We tested more than 1,000 putative enhancers by transgenesis assays in zebrafish to ascertain the identity of the target gene, with a focus on genes involved in X-linked intellectual disabilities (ID). The majority of active enhancers drive a transgenic expression in a pattern consistent with the known expression of a linked gene. These results show that evolutionary maintenance of linkage is a reliable predictor of an enhancer's function, and provide new information to discover the genetic basis of diseases caused by the mis-regulation of gene expression.
Project description:To study the evolutionary dynamics of regulatory DNA, we mapped >1.3 million deoxyribonuclease I–hypersensitive sites (DHSs) in 45 mouse cell and tissue types, and systematically compared these with human DHS maps from orthologous compartments. We found that the mouse and human genomes have undergone extensive cis-regulatory rewiring that combines branch-specific evolutionary innovation and loss with widespread repurposing of conserved DHSs to alternative cell fates, and that this process is mediated by turnover of transcription factor (TF) recognition elements. Despite pervasive evolutionary remodeling of the location and content of individual cis-regulatory regions, within orthologous mouse and human cell types the global fraction of regulatory DNA bases encoding recognition sites for each TF has been strictly conserved. Our findings provide new insights into the evolutionary forces shaping mammalian regulatory DNA landscapes.
Project description:In differentiated cells, inhibition of methyltransferases G9a and GLP eliminated H3K9me2 predominantly at A-type genomic compartments, and the remaining H3K9me2 marks were strongly associated with B-type compartments and lamina-associated domains (LADs). However, inhibition of G9a/GLP in mouse embryonic stem cells (ESCs) removed most of the H3K9me2 modifications in both A and B compartments. Furthermore, chemical inhibition of G9a/GLP in mouse hepatocytes decreased chromatin-nuclear lamina (NL) interactions, increased the degree of genomic compartmentalization and the boundary strength of topologically associating domains (TADs) between A and B compartments, and altered the expression of hundreds of genes that were associated with alterations of chromatin structure.
Project description:Coleoid cephalopods (squids, cuttlefish, octopus) have the largest nervous system among invertebrates that together with many lineage-specific morphological traits enables complex behaviors. The genomic basis underlying these innovations remains unknown. Using comparative and functional genomics in the model squid Euprymna scolopes, we reveal the unique genomic, topological, and regulatory organization of cephalopod genomes. We show that cephalopod genomes have been extensively restructured compared to other animals leading to the emergence of hundreds of tightly linked and evolutionary unique gene clusters (microsyntenies). Such novel microsyntenies correspond to topological compartments with a distinct regulatory structure and contribute to complex expression patterns. In particular, we identified a set of microsyntenies associated with cephalopod innovations (MACIs) broadly enriched in cephalopod nervous system expression. We posit that the emergence of MACIs was instrumental to cephalopod nervous system evolution and propose that microsyntenic profiling will be central to understand cephalopod innovations.
Project description:Measuring the properties of endogenous cell proteins, such as expression level, subcellular localization and turnover rates, on a whole proteome level remains a major challenge in the post-genome era. Quantitative methods for measuring mRNA expression do not reliably predict corresponding protein levels and provide little or no information on other protein properties. Here we describe a combined pulse-labelling, spatial proteomics and data analysis strategy to characterize the expression, localization, synthesis, degradation and turnover rates of endogenously expressed, untagged human proteins in different subcellular compartments. Using quantitative mass spectrometry and SILAC, a total of 80,098 peptides from 8,041 HeLa proteins were quantified, and their spatial distribution between the cytoplasm, nucleus and nucleolus determined and visualised using specialised software tools developed in PepTracker. Using information from ion intensities and rates of change in isotope ratios, protein abundance levels and protein synthesis, degradation and turnover rates were calculated for the whole cell and for the respective cytoplasmic, nuclear and nucleolar compartments. Expression levels of endogenous HeLa proteins varied by up to seven orders of magnitude. The average turnover rate for HeLa proteins was approximately 20 hours. Turnover rate did not correlate with either molecular weight or net charge, but did correlate with abundance, with highly abundant proteins showing longer than average half-lives. Fast turnover proteins had overall a higher frequency of PEST motifs than slow turnover proteins but no general correlation was observed between amino or carboxy terminal amino acid identities and turnover rates. A subset of proteins was identified that exist in pools with different turnover rates depending on their subcellular localization. This strongly correlated with subunits of large, multi-protein complexes, suggesting a general mechanism whereby their assembly is controlled in a different subcellular location to their main site of function.
Project description:Aim of this project is to perform a comparative genomic study (including all S. cerevisiae sequenced and available) of the variability and evolutionary traits of yeast.
Project description:We performed the CHIP-SEQ assay for LONP1 in C.elegans. Our findings suggest an evolutionary conserved mechanism where mtDNA-bound LONP1 serves as an internal sensor of organelle function that promotes mtDNA replication in dysfunctional compartments. We propose that if LONP1 activity declines, ATFS-1 avoids degradation and binds mtDNA to promote replication in an effort to recover the dysfunctional compartment, which inadvertently promotes ∆mtDNA replication in heteroplasmic cells.