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:Persistent exposure to antigen during chronic infection or cancer renders T cells dysfunctional. The molecular mechanisms regulating this state of exhaustion are thought to be common in infection and cancer, despite obvious differences in their microenvironments. We discovered that NFAT5, an NFAT family member lacking an AP-1 docking site, is highly expressed in exhausted T cells responding to chronic infection and tumors but is a central player selectively in tumor-induced exhaustion. While NFAT5 overexpression in CD8+ T cells reduced tumor control, NFAT5 deletion improved tumor control by promoting the accumulation of tumor-specific CD8 T cells that expressed less TOX and PD-1 and produced more cytokines specifically among precursor exhausted cells. Conversely, NFAT5 did not promote T cell exhaustion during chronic infection. While NFAT5 expression was induced by TCR triggering, its transcriptional activity was specific to the tumor microenvironment and required hyperosmolarity. NFAT5 thus promotes CD8 T cell exhaustion in a tumor-selective fashion.
Project description:Persistent exposure to antigen during chronic infection or cancer renders T cells dysfunctional. The molecular mechanisms regulating this state of exhaustion are thought to be common in infection and cancer, despite obvious differences in their microenvironments. We discovered that NFAT5, an NFAT family member lacking an AP-1 docking site, is highly expressed in exhausted T cells responding to chronic infection and tumors but is a central player selectively in tumor-induced exhaustion. While NFAT5 overexpression in CD8+ T cells reduced tumor control, NFAT5 deletion improved tumor control by promoting the accumulation of tumor-specific CD8 T cells that expressed less TOX and PD-1 and produced more cytokines specifically among precursor exhausted cells. Conversely, NFAT5 did not promote T cell exhaustion during chronic infection. While NFAT5 expression was induced by TCR triggering, its transcriptional activity was specific to the tumor microenvironment and required hyperosmolarity. NFAT5 thus promotes CD8 T cell exhaustion in a tumor-selective fashion.
Project description:Introgressed variants from other species can be an important source of genetic variation because they may arise rapidly, can include multiple mutations on a single haplotype, and have often been pretested by selection in the species of origin. Although introgressed alleles are generally deleterious, several studies have reported introgression as the source of adaptive alleles-including the rodenticide-resistant variant of Vkorc1 that introgressed from Mus spretus into European populations of Mus musculus domesticus. Here, we conducted bidirectional genome scans to characterize introgressed regions into one wild population of M. spretus from Spain and three wild populations of M. m. domesticus from France, Germany, and Iran. Despite the fact that these species show considerable intrinsic postzygotic reproductive isolation, introgression was observed in all individuals, including in the M. musculus reference genome (GRCm38). Mus spretus individuals had a greater proportion of introgression compared with M. m. domesticus, and within M. m. domesticus, the proportion of introgression decreased with geographic distance from the area of sympatry. Introgression was observed on all autosomes for both species, but not on the X-chromosome in M. m. domesticus, consistent with known X-linked hybrid sterility and inviability genes that have been mapped to the M. spretus X-chromosome. Tract lengths were generally short with a few outliers of up to 2.7 Mb. Interestingly, the longest introgressed tracts were in olfactory receptor regions, and introgressed tracts were significantly enriched for olfactory receptor genes in both species, suggesting that introgression may be a source of functional novelty even between species with high barriers to gene flow.
Project description:The low frequency of HBV-specific CD8+ T cells in the peripheral blood of CHB patients has limited studies of the mechanisms underlying HBV-induced T cell exhaustion. Similar to the expansion defect displayed in HBV-specific CD8+ T cells, TCR-induced proliferation of global CD8+ T cells is impaired in a fraction of chronic HBV (CHB) patients. Thus, examining the molecular regulation of global CD8+ T cell function in CHB patients may provide insight into the exhaustion of HBV-specific CD8+ T cells. We used microarrays to detail the global programme of gene expression of CD8 T cells from CHB patients who have not received anti-viral treatment. Fifteen milliliters of blood was drawn from eachof three CHB patients and three healthy donors. PBMCs were enriched using Ficoll, and CD8+ T cells were purified using positive selection beads to a purity of >95% (Miltenyi Biotec, Auburn, CA). Total RNA was extracted using a mirVana isolation kit (Life Technologies, Carlsbad, CA).
Project description:Comparison of genome-wide mRNA expresson between tumor-infiltrating CD8+ T cells from the tumor (hypofunctional T cells) and periphery (functional T cells) Mechanisms of self-tolerance often result in CD8+ tumor-infiltrating lymphocytes (TIL) with a hypofunctional phenotype incapable of tumor clearance. Using a solid tumor model in mice, we found that CD8+ T cells became tolerized in less than 24 hours in an established tumor environment. To define the collective impact of pathways suppressing TIL function, we compared genome-wide mRNA expression of tumor-specific CD8+ T cells from the tumor and periphery. Notably, gene expression induced during TIL hypofunction more closely resembled self-tolerance than viral-exhaustion. Differential gene expression was refined to identify a core set of genes that defined hypofunctional TIL; these data comprise the first âmolecular profileâ of tumor-specific TIL that are naturally responding and represent a polyclonal repertoire. The molecular profile of TIL was further dissected to determine the extent of overlap and distinction between pathways that collectively restrict T cell functions. As suggested by the molecular profile of TIL, protein expression of inhibitory receptor LAG-3 was differentially regulated throughout prolonged late-G1/early-S phase of the cell cycle. Our data may accelerate efficient identification of combination therapies to boost anti-tumor function of TIL specifically against tumor cells. 4 samples, 3 biological replicates per group.