Single Cell and Open Chromatin Analysis Reveals Molecular Origin of Epidermal Cells of the Skin
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ABSTRACT: Skin and its appendages such as hair follicle and sweat gland are formed by Keratin-5 expressing (Krt5+) epidermal cells that are specified from primitive, Keratin-8 expressing (Krt8+) ectodermal progenitors shortly after gastrulation. Here we show that transcription factor ∆Np63 is required for converting Krt8+ ectodermal progenitors to Krt5+ epidermal progenitors and priming the underlying dermal cells to form dermal condensate by activating the Wnt/ß-Catenin pathway. These findings unearth the molecular cascades during the fate specification of epidermal cells, illuminate the essential role of ∆Np63 in initiating the Wnt signaling in the epidermis and programming the underlying dermal cells and provide new possibilities to harness the intrinsic developmental program for generating the skin and its appendages.
Project description:Skin and its appendages such as hair follicle and sweat gland are formed by Keratin-5 expressing (Krt5+) epidermal cells that are specified from primitive, Keratin-8 expressing (Krt8+) ectodermal progenitors shortly after gastrulation. Here we show that transcription factor ∆Np63 is required for converting Krt8+ ectodermal progenitors to Krt5+ epidermal progenitors and priming the underlying dermal cells to form dermal condensate by activating the Wnt/ß-Catenin pathway. These findings unearth the molecular cascades during the fate specification of epidermal cells, illuminate the essential role of ∆Np63 in initiating the Wnt signaling in the epidermis and programming the underlying dermal cells and provide new possibilities to harness the intrinsic developmental program for generating the skin and its appendages.
Project description:Transcriptome analysis of urothelial KRT5-traced and KRT8-traced YFP-sorted cells with and without combinatorial loss of Trp53 and Pten. Bladders from 2-month-old KRT5-CreERT2, Rosa26YFP/LacZ mice, 2-month-old KRT8-CreERT2, Rosa26YFP/LacZ mice, 5-month-old KRT5-CreERT2, p53flox/flox, Ptenflox/flox, Rosa26YFP/+ mice, and 5-month-old KRT8-CreERT2, p53flox/flox, Ptenflox/flox, Rosa26YFP/+ mice were enzymatically dissociated, sorted for YFP by FACS, harvested, resuspended in Trizol and snap frozen for subsequent molecular analysis.
Project description:Eccrine sweat glands are indispensable for human thermoregulation and, similar to other mammalian skin appendages, form from multipotent epidermal progenitors. Limited understanding of how epidermal progenitors specialize to form these vital organs has precluded therapeutic efforts toward their regeneration. Herein, we applied single-nucleus transcriptomics to compare the expression content of wild-type, eccrine-forming mouse skin to that of mice harboring a skin-specific disruption of Engrailed 1 (En1), a transcription factor that promotes eccrine gland formation in humans and mice. We identify two concurrent but disproportionate epidermal transcriptomes in the early eccrine anlagen: one that is shared with hair follicles and one that is En1 dependent and eccrine specific. We demonstrate that eccrine development requires the induction of a dermal niche proximal to each developing gland in humans and mice. Our study defines the signatures of eccrine identity and uncovers the eccrine dermal niche, setting the stage for targeted regeneration and comprehensive skin repair.
Project description:The epidermis and associated appendages ensure a number of critical functions necessary for survival and social interactions. Perturbations of epidermal stem cell homeostasis lead to a variety of skin diseases affecting humans and dogs. Therefore, the establishment of an in vitro system to investigate canine epidermal stem cells, representing a model for human diseases, is essential. Here we report the establishment and characterization of organoids derived from microdissected canine hair follicles (HFs) and interfollicular epidermal (IFE). Gene and protein expression analysis revealed high mRNA and protein levels of keratin 5 and 14, IFE differentiation markers and intercellular molecules (e.g., keratin 10 and desmoglein), indicating a strong basal cell signature as well as differentiation towards mature epidermis. Key markers of HF stem cells were lacking. This suggests that, independently of the tissue of origin, both organoid lines develop into the same cell type (basal IFE-like keratinocytes). Signaling pathways members important for regulation of HF growth and cycling (such as Wnt, Hh, BMP and Notch) were present in both HF and IFE organoids at low levels. Withdrawal of growth factors (Noggin, R-spondin and FGFs) resulted in upregulation of markers such as KRT16, IVL, KRT17 and SOX9, showing the potential of the organoids to develop towards more differentiated tissue. However, for induction of HF signatures or hair growth, addition of different growth factors or dermal papilla co-culture might be required. Taken together, our in vitro culture system can provide the basis to address hair growth and explore epidermal function/regeneration, allowing us to further investigate pathomechanisms of cutaneous disorders in dogs and potentially human patients.
Project description:Animals develop skin regional specificities to best adapt to their environments. Birds are excellent models in which to study the epigenetic mechanisms that facilitate these adaptions. Patients suffering from SATB2 mutations exhibit multiple defects including ectodermal dysplasia-like changes. The preferential expression of SATB2, a chromatin regulator, in feather-forming compared to scale-forming regions, suggests it functions in regional specification of chicken skin appendages by acting on either differentiation or morphogenesis. Retrovirus mediated SATB2 misexpression in developing feathers, beaks, and claws causes epidermal differentiation abnormalities (e.g. knobs, plaques) with few organ morphology alterations. Chicken β-keratins are encoded in 5 sub-clusters (Claw, Feather, Feather-like, Scale, and Keratinocyte) on Chromosome 25 and a large Feather keratin cluster on Chromosome 27. Type I and II α-keratin clusters are located on Chromosomes 27 and 33, respectively. Transcriptome analyses showed these keratins 1) are often tuned up or down collectively as a sub-cluster, and 2) these changes occur in a temporo-spatial specific manner. This cluster-level suppression is also seen in MMPs on Chromosome 1. SATB2 alters gene expression changes of most other transcripts without this cluster-level switching. These results suggest an organizing role of SATB2 in cluster-level gene co-regulation during skin regional specification.
Project description:The nail unit and hair follicle are both hard keratin-producing organs that share various biological features. In this study, we demonstrated the presence of a nail-specific mesenchymal population called onychofibroblasts within the onychodermis. Onychodermis and follicular dermal papilla (DP) both expressed WNT and bone morphogenetic protein (BMP) signaling molecules. To analyze the function of BMP5 in nail development, we treated cultured human nail matrix keratinocytes (NMKs) with BMP5, which are highly expressed by onychofibroblasts. We observed increased expressions of hard keratin and HOXC13.
Project description:Following lung injury, alveolar regeneration is characterized by the transformation of alveolar type 2 (AT2) cells, via a transitional KRT8+ state, into alveolar type 1 (AT1) cells. In lung disease, dysfunctional intermediate cells accumulate, AT1 cells are diminished and fibrosis occurs. Using single cell RNA sequencing datasets of human interstitial lung disease, we found that interleukin-11 (IL11) is specifically expressed in aberrant KRT8 expressing KRT5-/KRT17+ and basaloid cells. Stimulation of AT2 cells with IL11 or TGFβ1 caused EMT, induced KRT8+ and stalled AT1 differentiation, with TGFβ1 effects being IL11 dependent. In bleomycin injured mouse lung, IL11 was increased in AT2-derived KRT8+ cells and deletion of Il11ra1 in lineage labeled AT2 cells reduced KRT8+ expression, enhanced AT1 differentiation and promoted alveolar regeneration, which was replicated in therapeutic studies using anti-IL11. These data show that IL11 maintains AT2 cells in a dysfunctional transitional state, impairs AT1 differentiation and blocks alveolar regeneration across species.
Project description:The p53 family member TP63 encodes two sets of isoforms, TAp63 and ∆Np63 isoforms, which are characterized by different N-termini and have diverse biological functions in epidermal morphogenesis and in cancer. In the skin, where their activities are best characterized, TAp63 prevents premature aging by regulating cellular senescence and genomic stability of stem cells, while ∆Np63 controls terminal differentiation of the basal cells in the epidermis. This functional diversity is surprising given that these isoforms share a high degree of similarity, including an identical DNA binding domain. To understand the mechanisms involved in the transcriptional programs leading to these diverse biological functions, we performed genome-wide analyses using p63-ChIP-seq and RNA-seq of TAp63-/- and ∆Np63-/- compared to wild-type primary mouse epidermal cells. Our data indicate that TAp63 and ∆Np63 recognize significantly different response elements on DNA and can physically and functionally interact with distinct transcription factors for the downstream regulation of their target genes. Our findings unveil previously uncharacterized transcriptomes activated by the p63 isoforms to regulate diverse biological functions in epidermal morphogenesis and homeostasis and cancer.
Project description:Distal airway stem cell (DASC) expressing basal cell restrictive transcription factor p63 and keratin-5 (Krt5) has a strong ability of regeneration after lung injury. Such cells are originated from primitive progenitors in distal airways and could expand/migrate to inflamed damaged lung parenchymal region to form ‘KRT5 pods’ once activated by various types of tissue injury. We isolated the mouse DASC and transplanted the GFP-labelled mDASC into the bleomycin-injured mouse lung by intratracheal instillation. Mice were sacrificed at 30 and 90 days post transplantation and their lung tissue were harvest to detect GFP signal by fluorescence stereomicroscope, the region of which was dissect for single cell-RNA-seq (scRNA-seq). We utilized scRNA-seq to trace the fate of transplanted mDASCs at 30 days and 90 days post transplantation, which revealed cell types differentiated from the transplanted DASCs.
Project description:Genome wide DNA methylation profiling of epidermal and dermal samples obtained from sun-exposed and sun-protected body sites from younger (<35 years old) and older (>60 years old) individuals. The Illumina Infinium 450k Human DNA methylation Beadchip was used to obtain DNA methylation profiles across approximately 450,000 CpGs in dermal and epidermal samples. Samples included 10 younger sun protected dermal samples, 10 younger sun exposed dermal samples, 10 older sun protected dermal samples, 10 older sun exposed dermal samples, 9 younger sun protected epidermal samples, 9 younger sun exposed epidermal samples, 10 older sun protected epidermal sample, 10 older sun exposed epidermal samples.