Project description:Organismal aging in mammals is manifested with architectural alteration and functional decline of multiple organs throughout the body. In aged skin, hairs are sparse, which has led to the hypothesis that the hair follicle stem cells (HFSCs) undergo epidermal differentiation during aging. Here, we employ single cell analysis to interrogate aging-related changes in the HFSCs. Unexpectedly, HFSCs maintain their lineage fidelity and show no signs of shifting to an epidermal fate. Despite maintaining lineage identity, HFSCs do show prevalent transcriptional changes in extracellular matrix genes. Of importance, these HFSC changes are accompanied by profound architectural perturbations in the aging stem cell niche. Upon surveying the dermis from young and aged skin, we also observe age-related changes in many non-epithelial cell types, including resident immune cells, sensory neurons, arrector pili muscles, and blood vessels – all of which have been previously associated with abilities to modulate hair follicle regeneration. Consistent with both intrinsic and extrinsic alterations in stem cell: niche communications, we find that in response to skin wounding, aged HFSCs repair the epidermis, but are defective in hair follicle regeneration. Intriguingly, whereas aged dermis cannot support young HFSCs, aged HFSCs can be rescued when supported by young dermis. Together, these findings favor a model where skin tissue microenvironment plays a dominant role in dictating the molecular properties and activities of HFSCs.
Project description:Aging human skin undergoes significant morphological and functional changes such as wrinkle formation, reduced wound healing capacity, and altered epidermal barrier function. Besides known age-related alterations like DNA-methylation changes, metabolic adaptations have been more recently linked to impaired skin function in old humans. Understanding of these metabolic adaptations in aged skin are of special interest, because topical treatments could reverse age-dependent metabolic changes of human skin in vivo to affect age associated skin disorders. Results: We investigated the global metabolic adaptions in human skin during aging with a combined transcriptomic and metabolomic approach applied to epidermal tissue samples of young and old human volunteers. Our analysis confirmed known age-dependent metabolic alterations, e.g. reduction of coenzyme Q10 levels, and also revealed novel age effects that are seemingly important for skin maintenance. Integration of donor-matched transcriptome and metabolome data highlighted transcriptionally-driven alterations of metabolism during aging such as altered activity in upper glycolysis and glycerolipid biosynthesis or decreased protein and polyamine biosynthesis. Together, we identified several age-dependent metabolic alterations that might affect cellular signaling, epidermal barrier function, and skin structure and morphology. Conclusion: Our study provides a global resource on the metabolic adaptations and its transcriptional regulation during aging of human skin. Thus, it represents a first step towards an understanding of the impact of metabolism on impaired skin function in aged humans and therefore will potentially lead to improved treatments of age related skin disorders
Project description:Mammalian epidermis consists of three self-renewing compartments: the hair follicle, sebaceous gland and interfollicular epidermis. We generated knock-in alleles of murine Lgr6, a close relative to the Lgr5 stem cell gene. Lgr6 was expressed in the earliest embryonic hair placodes. In adult hair follicles, Lgr6+ cells resided in a previously uncharacterized region directly above the follicle bulge. They expressed none of the known bulge stem cell markers. Prenatal Lgr6+ cells established the hair follicle, sebaceous gland and interfollicular epidermis. Postnatally, Lgr6+ cells generated sebaceous gland and interfollicular epidermis, while contribution to hair lineages gradually diminished with age. Adult Lgr6+ cells executed long-term wound repair, including the formation of new hair follicles. We conclude that Lgr6 marks the most primitive epidermal stem cell. For the Lgr5 and Lgr6 stem cell comparison RNA was isolated from sorted GFPhi cell fractions of dorsal skin from Lgr5-EGFP-ires-CreERT2 mice and Lgr6-EGFP-ires-CreERT2, respectively (3 mice per group per sort).
Project description:β-catenin signaling is required for hair follicle development, but it is unknown whether it is sufficient to activate expression of hair follicle genes in embryonic skin. To address this we profiled gene expression in skin dissected from E14.5 KRT14-Cre Ctnnb1(Ex3)fl/+ embryos carrying an activating mutation in epithelial beta-catenin, and control littermate embryos. Keywords: Genetic modification
Project description:Gene expression in self-renewing epithelial tissues is controlled by cis- and trans-activating regulatory factors that mediate responses to exogenous agents capable of causing tissue damage, infection, inflammation, or tumorigenesis. We used network construction methods to analyze the genetic architecture of gene expression in normal mouse skin in a cross between tumor-susceptible Mus musculus and tumor-resistant Mus spretus. We demonstrate that gene expression motifs representing different constituent cell types within the skin such as hair follicle cells, haematopoietic cells, and melanocytes are under separate genetic control. Motifs associated with inflammation, epidermal barrier function and proliferation are differentially regulated in mice susceptible or resistant to tumor development. The intestinal stem cell marker Lgr5 is identified as a candidate master regulator of hair follicle gene expression, and the Vitamin D receptor (Vdr) links epidermal barrier function, inflammation, and tumor susceptibility. Keywords: Expression Quantitative Trait Loci
Project description:Cyclosporine A (CSA) leads to the precocious onset of hair follicle growth, which is driven by premature activation and proliferation of hair follicle stem cells. Here, we identify gene expression changes associated with CSA treatment in hair follicle stem cells prior to the onset of proliferation as a readout for the early events in stem cell actvation. Hair follicle bulge stem cells were FACS-isolated from mouse skin during the 2nd telogen. Two biological replicated were performed.
Project description:We report the application of High throughout sequencing to explore the differences of skin between Super Merino sheep(SM) and Small Tail Han sheep, which have remarkable phenotype differences on wool and hair follicle traits. We analysed the expression data by CLC genomic workbench 9.0 software. We find there are 435 differential expressional genes (DEGs) (127 were up-regulated and 308 were down-regulated) when STH sheep as control group. Some hair follicle KRTs, KAPs genes and hair follicle stem cells marker genes, were up-regulated in SM sheep. However, some of mammalian epidermal development complex (EDC) family genes were up-regulated in STH sheep. The GO and gene network analysis shown high expression genes in SM sheep enriched on type I interferon, lipid/fatty acid synthesis metabolism. This study provide more details in skin which control the development of follicle and wool in sheep.
Project description:β-catenin signaling is required for hair follicle development, but it is unknown whether it is sufficient to activate expression of hair follicle genes in embryonic skin. To address this we profiled gene expression in skin dissected from E14.5 KRT14-Cre Ctnnb1(Ex3)fl/+ embryos carrying an activating mutation in epithelial beta-catenin, and control littermate embryos. Experiment Overall Design: Total skin RNA from two KRT14-Cre Ctnnb1(Ex3)fl/+ and two control littermate E14.5 embryos was hybridized to Affymetrix GeneChip Mouse Genome MOE430 2.0 oligonucleotide microarrays. Experiment Overall Design: Appended below is Table S3: Full list of differentially expressed genes in KRT14-Cre Ctnnb1(Ex3)fl/+ mutant compared with control littermate intact skin at E14.5, including normalization and filter parameters. Fold change, listed in the second column, gives the ratio of normalized mutant : control transcript levels.
Project description:Skin aging is characterized by structural and functional changes that lead to slower wound healing and higher rate of infections, which contribute to age-associated frailty. This likely depends on synergy between alterations in the local microenvironment and stem cell–intrinsic changes, underscored by pro-inflammatory microenvironments that drive pleotropic changes. To date, little is known about the precise nature and origin of the proposed age-associated inflammatory cues, or how they affect different tissue resident cell types. Based on deep single-cell RNA-sequencing of the entire dermal compartment, we now provide a comprehensive understanding of the age-associated changes in all skin cell types. We show a previously unreported skew towards an IL-17–expressing phenotype of Th cells, γδ T cells and innate lymphoid cells in aged skin. Aberrant IL-17 signaling is common to many autoimmune (e.g., rheumatoid arthritis and psoriasis) and chronic inflammatory diseases. Importantly, in vivo blockade of IL-17–triggered signaling during the aging process reduces the pro-inflammatory state by affecting immune and non-immune skin cells of both dermis and epidermis. Strikingly, IL-17 neutralization significantly delays the appearance of age-related traits, such as decreased epidermal thickness, increased cornified layer thickness and ameliorated hair follicle stem cell activation and hair shaft regeneration. Our results indicate that the aged skin shows chronic and persistent signs of inflammation, and that age-associated increased IL-17 signaling could be targeted as a strategy to prevent age-associated skin ailments in elderly.
Project description:Studies in model organisms suggest that aged cells can be functionally rejuvenated, but whether this concept applies to human skin is unclear. Here we apply deep sequencing of RNA 3' ends ("3-seq") to discover the gene expression program associated with human photoaging and intrinsic skin aging (collectively termed "skin aging") and the impact of broadband light (BBL) treatment. We find that skin aging was associated with the significantly altered expression level of 2,265 coding and noncoding RNAs, of which 1,293 became "rejuvenated" after BBL treatment, i.e. more similar in expression level of youthful skin. Rejuvenated genes (RGs) included several known key regulators of organismal longevity and their proximal long non-coding RNAs. Skin aging is not associated with systematic changes in 3' end mRNA processing. Hence, BBL treatment can restore the gene expression pattern of photoaged and intrinsically aged human skin to resemble young skin. In addition, our data reveals a novel set of targets that may lead to new insights into the human skin aging process. Examination of broadband light treated and untreated human skin transcriptomes of 5 women aged 50 years or more. They were compared to the skin transcriptomes of 5 young women aged 30 years or less.