Project description:We report genome-wide pattern of Myb chromatin occupancy in vivo. We used ERMYB, a myeloid progenitor cell line derived by transformation of primary cells by ER-Myb fusion protein, as our model system. In these cells, activation of the ER-Myb fusion protein by estrogen is required to maintain a proliferative progenitor-like phenotype. We performed ChIP-seq with biological duplicate samples from ERMYB cells with Myb either “on” or “off” (i.e. + or - ?-E2 for 6 hr). By comparing enrichment signals between Myb-on, Myb-off and isotype control samples, we identified 7,646 high-confidence Myb binding regions, which can be assigned to 4,892 annotated genes according to their distances to the nearest transcriptional start sites. Examination of Myb chromatin occupany in myeloid cells transformed by a switchable form of Myb
Project description:We report genome-wide pattern of Myb chromatin occupancy in vivo. We used ERMYB, a myeloid progenitor cell line derived by transformation of primary cells by ER-Myb fusion protein, as our model system. In these cells, activation of the ER-Myb fusion protein by estrogen is required to maintain a proliferative progenitor-like phenotype. We performed ChIP-seq with biological duplicate samples from ERMYB cells with Myb either “on” or “off” (i.e. + or - β-E2 for 6 hr). By comparing enrichment signals between Myb-on, Myb-off and isotype control samples, we identified 7,646 high-confidence Myb binding regions, which can be assigned to 4,892 annotated genes according to their distances to the nearest transcriptional start sites.
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 Myb proto-oncogene encodes the transcription factor c-MYB, which is critical for the proliferation and differentiation of hematopoietic stem and progenitor cells. Distant enhancers of Myb expression have been characterized but the regulation of Myb during hematopoiesis is still incompletely understood. Here we identified a novel nuclear Myb enhancer long intergenic non-coding RNA (Myrlin) that originates from the -81 kb murine Myb enhancer within the Myb ─ Hbs1l intergenic region. Myrlin and Myb are coordinately regulated in a developmental stage-specific fashion during maturation of erythroid progenitors and upon differentiation of MEL cells. CRISPR/Cas9 genome editing of the Myrlin transcription start site at the -81kb enhancer reduced both Myrlin and Myb expression. The deletion of Myrlin TSS reduces the occupancy of LDB1, which mediates chromatin looping, and compromises long-range contacts between the Myb promoter and enhancer and RNA Pol II occupancy decreases across the Myb locus. In contrast, silencing of Myrlin using CRISPRi similarly reduced both Myrlin and Myb expression but left the Myb enhancer hub undisturbed, separating chromatin looping from transcription activation of Myb. In unedited cells, we found that Myrlin interacts with MLL1 complex, a transcriptional coactivator that plays an essential role in regulating gene expression during hematopoiesis. Myrlin CRISPRi compromised MLL1 occupancy in the Myb locus and decreased CDK9 and RNA Pol II binding. Myrlin CRISPRi further resulted in pausing of RNA Pol II in the Myb first exon/intron. These data suggest that Myrlin directly participates in activating Myb transcription by recruiting MLL1.
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.