Project description:Gut immunocompetence involves immune, stress, and regenerative processes. To investigate the determinants underlying inter-individual variation in gut immunocompetence, we perform enteric infection of 140 Drosophila lines with the entomopathogenic bacterium Pseudomonas entomophila and observe extensive variation in survival. Using genome-wide association analysis, we identify several novel immune modulators. Transcriptional profiling further shows that the intestinal molecular states of resistant and susceptible lines differ, already before infection, with one transcriptional module involving genes linked to reactive oxygen species (ROS) metabolism contributing to this difference. This genetic and molecular variation is physiologically manifested in lower ROS activity, lower susceptibility to ROS-inducing agent, faster pathogen clearance and higher stem cell activity in resistant versus susceptible lines. This study provides novel insights into the determinants underlying population-level variability in gut immunocompetence, revealing how relatively minor, but systematic genetic and transcriptional variation can mediate overt physiological differences that determine enteric infection susceptibility.
Project description:Comparative genomics studies in primates are extremely restricted due to our limited access to samples from non-human apes. In order to gain better insight into the genetic processes that underlie variation in complex phenotypes in primates, we must have access to faithful model systems for a wide range of cell types. To facilitate this, we have generated a panel of 7 fully characterized chimpanzee induced pluripotent stem cell (iPSC) lines derived from healthy donors. To begin demonstrating the utility of comparative iPSC panels, we collected RNA-sequencing and DNA methylation data from the chimpanzee iPSCs and the corresponding fibroblast lines, as well as from 7 human iPSCs and their source lines, which encompass multiple populations and cell types. We observe much less within-species variation in iPSCs than in somatic cells, indicating that the reprogramming process erases many inter-individual differences. The low within-species regulatory variation in iPSCs allowed us to identify many novel inter-species regulatory differences of small magnitude.
Project description:Genome-wide gene expression studies may provide a comprehensive insight in gene activities and biological pathways differing between individuals and tissues (even closely related tissues building complex organs such as the brain). Our research addressed both kinds of gene expression variation – between brain regions and between individuals – by expression profiling in brain tissues derived from eight brain regions and blood from 12 vervet monkeys (Chlorocebus aethiops sabaeus). We employed the non-human primate model to assure tissue quality and to enhance the probability of precise dissection of the brain tissues, which is difficult to realize in human subjects. We characterized brain regional differences in gene expression levels which may relate to specific functions of brain tissues including disease symptoms affecting specific brain regions. We focused on inter-individual variability of brain transcript levels in different regions that correlates well between blood and brain tissues and therefore could be further reliably studied in easily accessible blood samples. Applying very stringent transcript selection criteria including 1). considerable similarities between brain and blood tissues, 2). consistent repeat measurements in blood, 3). higher inter-individual than intra-individual variability and 4). detection in all tissue samples, allowed us to identify transcripts in which inter-individual variation in brain expression profiles indicates possible genetic factors regulating gene transcript levels. High heritabilities of these transcript levels indicated that our approach focusing on transcripts showing higher inter-individual variability than intra-individual variability identifies transcripts with a strong genetic component.
Project description:Comparative genomics studies in primates are extremely restricted due to our limited access to samples from non-human apes. In order to gain better insight into the genetic processes that underlie variation in complex phenotypes in primates, we must have access to faithful model systems for a wide range of cell types. To facilitate this, we have generated a panel of 7 fully characterized chimpanzee induced pluripotent stem cell (iPSC) lines derived from healthy donors. To begin demonstrating the utility of comparative iPSC panels, we collected RNA-sequencing and DNA methylation data from the chimpanzee iPSCs and the corresponding fibroblast lines, as well as from 7 human iPSCs and their source lines, which encompass multiple populations and cell types. We observe much less within-species variation in iPSCs than in somatic cells, indicating that the reprogramming process erases many inter-individual differences. The low within-species regulatory variation in iPSCs allowed us to identify many novel inter-species regulatory differences of small magnitude. We used ChIP-seq to characterize the genome-wide distribution of two types of histone modifications (H3K27me3 and H3K27ac) in three of our chimpanzee iPSCs and compared them to histone modification data from three human iPSC lines from the Roadmap Epigenomics project:
Project description:Analysis of the extent to which inter-individual variation in mRNA decay contributes to inter-individual variation in gene expression levels in humans. The study examines properties of genome-wide decay rates and the relationship between mRNA decay and gene expression across genes, across individuals, and finally across genotype classes.
Project description:Phosphorylation of proteins on serine, threonine, and tyrosine residues is a ubiquitous post-translational modification that plays a key part of essentially every cell signaling process. It is reasonable to assume that inter-individual variation in protein phosphorylation may underlie phenotypic differences, as has been observed for practically any other molecular regulatory phenotype. However, we do not know much about the extent of inter-individual variation in phosphorylation because it is quite challenging to perform a quantitative high throughput study to assess inter-individual variation in any post-translational modification. To test our ability to address this challenge with current technology, we quantified phosphorylation levels for three fully sequenced human cell lines within a nested experimental framework, and found that genetic background is the primary determinant of phosphoproteome variation. We uncovered multiple functional, biophysical, and genetic associations with germline driven phosphopeptide variation (though the small sample size in this ‘pilot’ study limits the applicability of our genetic observations). Among these associations were variants affecting protein levels or structure, with the latter presenting, on average, a stronger effect. Interestingly, we found evidence that is consistent with a phosphopeptide variability buffering effect endowed from properties enriched within longer proteins. We also undertook a thorough technical assessment of our experimental workflow to aid further efforts. Taken together, this work provides the foundation for future work to characterize inter-individual variation in post-translational modification as well as reveals novel insights into the nature of inter-individual variation in phosphorylation.