Project description:To determine functional overlap between cMyc and AP4 in CD8+ T cell priming, we retrovirally expressed cMyc or AP4 in cMyc-deficient CD8+ T cells and examined gene expression after activation.
Project description:To determine functional overlap between cMyc and AP4 in CD8+ T cell priming, we retrovirally expressed cMyc or AP4 in cMyc-deficient CD8+ T cells and examined gene expression after activation. Naive CD8+ T cells from Myc conditional knockout mice with a tamoxifen inducible Cre transgene were retrovirally transduced with Myc or AP4 followed by a treatment with 4-hydroxytamoxifen in the presence of IL-7 for 2 days. RNA was harvested 48 hours after restimulation of transduced cells with anti-CD3 antibody and gene expression was compared by microarray. CD8+ T cells from littermate wildtype mice that were transduced with an empty retrovirus were used as control.
Project description:The trasncription factor cMyc is an essential transcription factor that establishes a metabolically active and proliferative state in T cells after antigen priming. However, its expression is transient. To date, it remains unknown how T cell activation is maintained after cMyc down-regulation. Here, we identify AP4, encoded by the gene Tfap4, as the transcription factor that is induced by cMyc and sustains activation of antigen-specific CD8+ T cells. Despite normal priming, Tfap4–/– CD8+ T cells fail to continue transcription of a broad range of cMyc gene targets necessary for sustained proliferation. Genome-wide analysis suggests that many activation-induced metabolic genes are shared targets of cMyc and AP4. Thus, AP4 maintains Myc-initiated cellular activation programs in CD8+ T cells to control microbial infections. Naive CD8+ T cells from C57BL6 mice were activated with anti-CD3 and anti-CD28 stimulation in vitro for two days and genome-wide occupancy of Myc, AP4 and Ser2 or Ser5 phipsphorylated RNA polymerase II was profiled by chromatin immunoprecipitation and high-throughput sequencing.
Project description:The trasncription factor cMyc is an essential transcription factor that establishes a metabolically active and proliferative state in T cells after antigen priming. However, its expression is transient. To date, it remains unknown how T cell activation is maintained after cMyc down-regulation. Here, we identify AP4, encoded by the gene Tfap4, as the transcription factor that is induced by cMyc and sustains activation of antigen-specific CD8+ T cells. Despite normal priming, Tfap4–/– CD8+ T cells fail to continue transcription of a broad range of cMyc gene targets necessary for sustained proliferation. Genome-wide analysis suggests that many activation-induced metabolic genes are shared targets of cMyc and AP4. Thus, AP4 maintains Myc-initiated cellular activation programs in CD8+ T cells to control microbial infections.
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: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.