Project description:The importance of unanchored Ub in innate immunity has been shown only for a limited number of unanchored Ub-interactors. We investigated what additional cellular factors interact with unanchored Ub and whether unanchored Ub plays a broader role in innate immunity. To identify unanchored Ub-interacting factors from murine lungs, we used His-tagged recombinant poly-Ub chains as bait. These chains were mixed with lung tissue lysates and protein complexes were isolated with Ni-NTA beads. Sample elutions were subjected to mass spectrometry (LC-MSMS) analysis.
Project description:Cellular binary fate decisions require the progeny to silence genes associated with the alternative fate. The major subsets of alpha:beta T cells have been extensively studied as a model system for fate decisions. While the transcription factor RUNX3 is required for the initiation of Cd4 silencing in CD8 T cell progenitors, it is not required to maintain the silencing of Cd4 and other helper T lineage genes. The other runt domain containing protein, RUNX1, silences Cd4 in an earlier T cell progenitor, but this silencing is reversed whereas the gene silencing after RUNX3 expression is not reverse. Therefore, we hypothesized that RUNX3 and not RUNX1 recruits other factors that maintains the silencing of helper T lineage genes in CD8 T cells. To this end, we performed a proteomics screen of RUNX1 and RUNX3 to determine candidate silencing factors.
Project description:Dendritic cell activation through ligation of pattern recognition receptors leading to full functional maturation causes induction of CD8 T cell immunity instead of tolerance through increased delivery of co-stimulatory signals. Here we investigate whether a prototypic organ-resident antigen-presenting cells, i.e. liver sinusoidal endothelial cells (LSEC), also switch from tolerogenic to immunogenic CD8 T cell activation upon such activation. We demonstrate by gene expression analysis that LSEC expressed numerous pattern recognition receptors that attributed sentinel function, but ligand-induced activation of these receptors was not sufficient to overcome tolerance induction of CD8 T cells. However, viral infection caused functional maturation of antigen-presenting LSEC and was sufficient to promote antigen-specific differentiation into fully functional effector CD8 T cells in the absence of dendritic cells. Thus, we identify a novel principle of inducing CD8 T cell immunity by virally infected organ-resident antigen-presenting cells employing distinct mechanisms compared to dendritic cells.
