The human hair follicle bulge is an important niche for keratinocyte stem cells (KSC). Elucidation of human bulge cell biology could be facilitated by analysis of global gene expression profiles and identification of unique cell surface markers. The lack of distinctive bulge morphology in human hair follicles has hampered studies of bulge cells and KSC. In this study, we determined the distribution of label-retaining cells to carefully define the human anagen bulge. Using navigated-laser capture microdissection, bulge cells and outer root sheath cells from other follicle regions were obtained and analyzed with cDNA microarrays. Gene transcripts encoding inhibitors of WNT and Activin/BMP signaling were over-represented in the bulge while genes responsible for cell proliferation were under-represented, consistent with quiescent non-cycling KSC in anagen follicles. Positive markers for bulge cells included CD200, PHLDA1, follistatin, and frizzled homolog 1 while CD24, 34, 71 and 146 were preferentially expressed by non-bulge keratinocytes. Importantly, CD200+ cells (CD200hi24lo34lo71lo146lo) obtained from hair follicle suspensions demonstrated high colony forming efficiency in clonogenic assays, indicating successful enrichment of living human bulge stem cells.
Characterization and isolation of stem cell-enriched human hair follicle bulge cells.
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View SamplesHistone variant H2A.Z occupies the promoters of active and poised, bivalent genes in ESCs to regulate developmental programs, yet how it contributes to these contrasting states is poorly understood. Here, we investigate the function of H2A.Z.1 mono-ubiquitylation (H2A.Z.1ub) by mutation of the PRC1 target residues (H2A.Z.1K3R3). We show that H2A.Z.1K3R3 is properly incorporated at target promoters in murine ESCs (mESCs), however, loss of mono-ubiquitylation leads to de-repression of bivalent genes, loss of Polycomb binding, and to faulty lineage commitment. Using quantitative proteomics, we find that tandem bromodomain proteins, including the BET family member Brd2, are enriched in H2A.Z.1 chromatin. We further show that Brd2 is gained at de-repressed promoters in H2A.Z.1K3R3 mESCs whereas Brd2 inhibition restores gene silencing at these sites. Together, our study reveals an antagonistic relationship between H2A.Z.1ub and Brd2 to regulate the transcriptional balance at bivalent genes to enable proper execution of developmental programs. Overall design: RNA-Seq analysis on mouse embryonic stem cells harboring H2A.Z or H2A.Z.K3R3 (3 C-terminal lysines mutated to arginines) tagged with YFP, in the presence of a knockdown hairpin targeting the endogenous H2A.Z transcript.
H2A.Z.1 Monoubiquitylation Antagonizes BRD2 to Maintain Poised Chromatin in ESCs.
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View SamplesThymic stromal lymphopoietin (TSLP) is a type I cytokine that plays a central role in induction of allergic inflammatory responses. Its principal targets have been reported to be dendritic cells and / or CD4 T cells; epithelial cells are a principal source. We report here the development of a reporter mouse (TSLP-ZsG) in which a ZsGreen (ZsG)-encoding construct has been inserted by recombineering into a bacterial artificial chromosome (BAC) immediately at the translation initiating ATG of TSLP. The expression of ZsG by mice transgenic for the recombinant BAC appears to be a faithful surrogate for TSLP expression, particularly in keratinocytes and medullary thymic epithelials cells (mTECs). A comparison of gene expression in ZsG expressing and ZsG negative mTECs and cortical thymic epithelial cells, which are all ZsG negative, revealed that all three populations can be distinguished from one another. In particular ZsG (and TSLP) expressing mTECs and ZsG- mTECs are separable populations based on gene expression profiling. Little or no expression of ZsG is observed in bone marrow-derived mast cells or basophils or in CD45+ cells infiltrating TSLP/ZsG-expressing skin. Using the TSLP-ZsG reporter mouse, we show that TNFa and IL-4/IL-13 are potent inducers of TSLP expression by keratinocytes and that local activation of Th2 and Th1 cells induces keratinocyte TSLP expression. We suggest that the capacity of TSLP to both induce Th2 differentiation and to be induced by activated Th2 cells raises the possibility that TSLP may be involved in a positive feedback loop to enhance allergic inflammatory conditions.
TSLP expression: analysis with a ZsGreen TSLP reporter mouse.
Specimen part, Treatment
View SamplesDespite widespread use of sunscreens that minimize erythema by blocking ultraviolet B (UVB) radiation, incidence rates of melanoma continue to rise. In considering this disparity between intervention and disease prevalence, we investigated the in vivo transcriptome of human skin treated with sunscreen and solar-simulated radiation (ssR). A focal skin area of healthy participants was exposed to ssR at 1 minimal erythema dose (MED), 0.1 MED or 100 J/m2 with or without prior application of sunscreen, or to non-UVB-spectrum of ssR (solar-simulated UVA/visible/infrared radiation: ssA). Skin biopsies were analyzed using expression microarrays.
Transcriptional signatures of full-spectrum and non-UVB-spectrum solar irradiation in human skin.
Sex, Specimen part
View SamplesIn support of the investigation into the response of tissue resident phagocytes to sterile tissue damage in the peritoneal wall, different phagocyte populations were isolated from this tissue and RNA expression was measured using RNAseq. Overall design: Peritoneal wall phagocytes from three Cx3cr1gfp/+Ccr2rfp/+ animals were sorted into Cx3cr1-Ccr2rfp-, Cx3cr1-Ccr2rfp+, and Cx3cr1+Ccr2rfp- groups. Cells from three mice were sorted, and carried through the RNAseq protocol as three replicates per group.
Resident Macrophages Cloak Tissue Microlesions to Prevent Neutrophil-Driven Inflammatory Damage.
Specimen part, Subject
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