Presenter: Musa Hassan
Thursday, 4:00 – 6:00pm
Musa A. Hassan1, Kirk D. Jensen1, Vincent Butty1, Pjotr Prins2, Jeroen P. J. Saeij1 1Massachusetts Institute of Technology, Department of Biology, Cambridge, MA, USA 2Laboratory of Nematology, Wageningen University, Wageningen, The Netherlands
Individual variation in macrophage responsiveness to cytokines, such as interferon gamma (IFNγ) and tumor necrosis factor alpha (TNFα), or conserved pathogen-associated molecular patterns, such as LPS and CpG, is thought to result in variable disease phenotypes between individuals with divergent genetic background. Therefore, we aimed to elucidate the molecular mechanisms underlying variation in macrophage response to inflammatory stimuli and to infection with the obligate intracellular pathogen Toxoplasma gondii, a common opportunistic pathogen in immunodeficient individuals.
By combining transcriptional and linkage analysis of bone marrow-derived macrophages obtained from recombinant inbred mice, we show that in resting macrophages, differential transcriptional profiles are mostly regulated in cis, while the differential responsiveness to stimulation or Toxoplasma is largely determined by a small number of loci with large effects on the expression of many genes. Additionally, we identified a locus on mouse chr 2 that regulates both mouse and Toxoplasma gene expression, and a locus on chr 3 that regulates parasite growth in vitro. Finally, by leveraging the power of RNA-seq, we identified and provide evidence for genetic linkage to differential alternative splicing and mRNA editing. We have validated some of these results using used shRNA-mediated knockdown assays.
Because activation of macrophages by IFNγ and TNFα confers resistance to many pathogens, many of which have overlapping susceptibility loci, we expect that the data generated in this study will help to identify genes important in mediating response to other pathogens.