Project description:The Wnt/alpha-catenin pathway plays a central role in epidermal homeostasis and regeneration but how it affects fibroblast fate decisions is unknown. Here, we investigated the effect of targeted alpha-catenin stabilization in dermal fibroblasts. Comparative gene expression profiling of Sca1- and Sca1+ neonatal fibroblasts, from upper and lower dermis respectively, confirmed that Sca1+ cells had a pre-adipocyte signature and revealed differential expression of Wnt/alpha‐catenin-associated genes. By targeting all fibroblasts or selectively targeting Dlk1+ lower dermal fibroblasts, we found that -catenin stabilization between E16.5 and P2 resulted in a reduction in the dermal adipocyte layer with a corresponding increase in dermal fibrosis and an altered hair cycle. The fibrotic phenotype correlated with a reduction in the potential of Sca1+ fibroblasts to undergo adipogenic differentiation ex vivo. Our findings indicate that Wnt/alpha-catenin signaling controls adipogenic cell fate within the lower dermis, which potentially contributes to the pathogenesis of fibrotic skin diseases.
Project description:The Wnt/alpha-catenin pathway plays a central role in epidermal homeostasis and regeneration but how it affects fibroblast fate decisions is unknown. Here, we investigated the effect of targeted alpha-catenin stabilization in dermal fibroblasts. Comparative gene expression profiling of Sca1- and Sca1+ neonatal fibroblasts, from upper and lower dermis respectively, confirmed that Sca1+ cells had a pre-adipocyte signature and revealed differential expression of Wnt/alphaâ??catenin-associated genes. By targeting all fibroblasts or selectively targeting Dlk1+ lower dermal fibroblasts, we found that ï?¢-catenin stabilization between E16.5 and P2 resulted in a reduction in the dermal adipocyte layer with a corresponding increase in dermal fibrosis and an altered hair cycle. The fibrotic phenotype correlated with a reduction in the potential of Sca1+ fibroblasts to undergo adipogenic differentiation ex vivo. Our findings indicate that Wnt/alpha-catenin signaling controls adipogenic cell fate within the lower dermis, which potentially contributes to the pathogenesis of fibrotic skin diseases. The dermis was separated from back skin of PDGFRAeGFP postnatal pups (P2) by incubation with thermolysin (0.25 mg/ml) (Sigma T7902) overnight at 4° and further processed as previously described (Collins et al., 2011). Cells were labeled in PBS + 10% FBS TruStain fcX anti-mouse blocking buffer with the following antibodies: anti-mouse Ly-6A/E (Sca-1)-Alexa Fluor-700 17. Two populations of cells were collected in triplicate. The PDGFRaH2BeGFP/Sca1- and the PDGFRaH2BeGFP/Sca1+. RNA was isolated and prepared for microarray analysis and hybridized to Affymetrix MG430.2A arrays. C, digested in DMEM + 10% FBS containing 2.5 mg/mL collagenase I (Gibco 17100- 017), and further processed
Project description:The dermis is divided into two distinct layers. The upper, papillary dermis is characterized by thin and sparse fibers. The lower, reticular dermis is composed of solid tissue made up of thicker highly dense fibers. It has been reported that cultured fibroblasts isolated from the papillary and the reticular dermis exhibit different properties. In this study, we analyzed gene expression profiles of human papillary dermis and reticular dermis obtained using laser capture microdissection.
Project description:Fibroblasts are the main dermis-resident cells, yet they remain poorly characterized. Fundamentally, fibroblasts originate from the same population of mesenchymal cells but fibroblast subpopulations have been identified. Papillary and reticular fibroblasts were characterized based on their respective location in the papillary and reticular dermis. Here, we identified a new subset of fibroblasts, located in human papillary dermis and displaying specific features such as their organization into cell clusters. We used microarrays to detail the gene expression profiles of the novel fibroblast subpopulation we have identified compared to papillary and reticualr fibroblasts and notably the relative contribution of the different fibroblast subpopulations to the extracellular matrix of the dermis.
Project description:The upper papillary and deeper reticular dermis differ structurally and functionally. Although the papillary and reticular fibroblasts produced distinct extracellular matrix (ECM), the matrisome of these two fibroblast subpopulations has not been defined. Therefore we performed a transcriptomic analysis of papillary and reticular fibroblasts freshly isolated from skin of young donors around 20, at a time they produced high level of ECM. Bioinformatics analysis delivered 230 upregulated and 139 downregulated transcripts in papillary vs reticular fibroblasts. Expression of various selected genes was validated by q-PCR. The papillary fibroblasts were characterized by a higher expression of genes involved in the defense function, in the regulation of cell motility and proliferation and in the MAPK cascade whereas reticular fibroblasts showed higher expression of genes related to the development of connective tissues. Papillary fibroblasts were characterized by the expression of a high number of matrisome-associated genes whereas reticular fibroblasts gene signature mainly related to the core matrisome and ECM regulators. The regulation of selected genes was validated at protein level attesting to the robustness of the transcriptome analysis. Altogether, our data brought new insights into an ECM signature that is coherent with the organization and function of the papillary and reticular dermis.
Project description:Forced expression of activated beta-catenin in mouse dermal fibroblasts is sufficient to cause spontaneous, progressive skin fibrosis in vivo. We generated triple-transgenic HoxB6CreERT/+; R26-YFP/+; CatnbΔex3/+ "activated beta-catenin" mice and double-transgenic HoxB6CreERT/+; R26-YFP/+ littermate control mice. We induced Cre activity (resulting in expression of activated beta-catenin in triple-transgenic mutant fetuses) by administering tamoxifen to the pregnant dam at embryonic day 16.5. The activated beta-catenin mice developed fibrotic skin, characterized by elevated collagen deposition and increased fibroblast proliferation. We performed RNA-sequencing to profile gene expression in the dermis of control and activated beta-catenin mutant mice with established skin fibrosis at 3 weeks of age.
Project description:Myeloid cell lines (K562 and HEL) were treated overnight with CHIR99021 or a vehicle control (DMSO). CHIR99021 treatment inhibits GSK3B within the destruction complex functioning in Wnt/beta-catenin signalling pathway, thereby preventing beta-catenin degradation and promoting its stabilization. Following the overnight incubation, beta-catenin RIP (RNA immunoprecipitation) was performed in both K562 and HEL cells. RNA samples obtained from beta-catenin RIP in these cells were then sequenced to identify beta-catenin-associated RNAs under CHIR99021 treatment compared to basal conditions (DMSO control).
Project description:Hair follicle formation depends on reciprocal epidermal-dermal interactions and occurs during skin development, but not in adult life. This suggests that the properties of dermal fibroblasts change during postnatal development. To examine this, we used a PdgfraEGFP mouse line to isolate GFP-positive fibroblasts from neonatal skin, adult telogen and anagen skin and adult skin in which ectopic hair follicles had been induced (EF skin) by transgenic epidermal activation of beta-catenin. We also isolated epidermal cells from each mouse. The gene expression profile of EF epidermis was most similar to that of anagen epidermis, consistent with activation of beta-catenin signalling. In contrast, adult dermis with ectopic hair follicles more closely resembled neonatal dermis than adult telogen or anagen dermis. In particular, genes associated with mitosis were upregulated and extracellular matrix-associated genes were downregulated in neonatal and EF fibroblasts. We confirmed that sustained epidermal beta-catenin activation stimulated fibroblasts to proliferate to reach the high cell density of neonatal skin. In addition, the extracellular matrix was comprehensively remodelled, with mature collagen being replaced by collagen subtypes normally present only in developing skin. The changes in proliferation and extracellular matrix composition originated from a specific subpopulation of fibroblasts located beneath the sebaceous gland. Our results show that adult dermis is an unexpectedly plastic tissue that can be reprogrammed to acquire the molecular, cellular and structural characteristics of neonatal dermis in response to cues from the overlying epidermis.
Project description:Hair follicle formation depends on reciprocal epidermal-dermal interactions and occurs during skin development, but not in adult life. This suggests that the properties of dermal fibroblasts change during postnatal development. To examine this, we used a PdgfraEGFP mouse line to isolate GFP-positive fibroblasts from neonatal skin, adult telogen and anagen skin and adult skin in which ectopic hair follicles had been induced (EF skin) by transgenic epidermal activation of beta-catenin. We also isolated epidermal cells from each mouse. The gene expression profile of EF epidermis was most similar to that of anagen epidermis, consistent with activation of beta-catenin signalling. In contrast, adult dermis with ectopic hair follicles more closely resembled neonatal dermis than adult telogen or anagen dermis. In particular, genes associated with mitosis were upregulated and extracellular matrix-associated genes were downregulated in neonatal and EF fibroblasts. We confirmed that sustained epidermal beta-catenin activation stimulated fibroblasts to proliferate to reach the high cell density of neonatal skin. In addition, the extracellular matrix was comprehensively remodelled, with mature collagen being replaced by collagen subtypes normally present only in developing skin. The changes in proliferation and extracellular matrix composition originated from a specific subpopulation of fibroblasts located beneath the sebaceous gland. Our results show that adult dermis is an unexpectedly plastic tissue that can be reprogrammed to acquire the molecular, cellular and structural characteristics of neonatal dermis in response to cues from the overlying epidermis. We have isolated the following populations of cells from mouse back skin by flow cytometry: 1A) GFP+ WT neonatal dermal fibroblasts, 1B) ItgA6+ WT neonatal epidermal keratinocytes, 2A) GFP+ WT telogen dermal fibroblasts, 2B) ItgA6+ WT telogen epidermal keratinocytes, 3A) GFP+ D2 transient activation (anagen) dermal fibroblasts, 3B) ItgA6+ D2 transient activation (anagen) epidermal keratinocytes, 4A) GFP+ D2 sustained activation (ectopic follicles) dermal fibroblasts, 4B) ItgA6+ D2 sustained activation (ectopic follicles) epidermal keratinocytes
Project description:Idiopathic pulmonary fibrosis (IPF) is a progressive disease of the middle aged and elderly with a prevalence of one million persons worldwide. The fibrosis spreads from affected alveoli into contiguous alveoli, creating a reticular network that leads to death by asphyxiation. Lung fibroblasts from patients with IPF have phenotypic hallmarks, distinguishing them from their normal counterparts: pathologically activated Akt signaling axis, increased collagen and a-smooth muscle actin expression, distinct gene expression profile, and ability to form fibrotic lesions in model organisms. Despite the centrality of these fibroblasts in disease pathogenesis, their origin remains uncertain. Here, we report the identification of cells in the lungs of patients with IPF with the properties of mesenchymal progenitors. In contrast to progenitors isolated from nonfibrotic lungs, IPF mesenchymal progenitor cells produce daughter cells manifesting the full spectrum of IPF hallmarks, including the ability to form fibrotic lesions in zebrafish embryos and mouse lungs, and a transcriptional profile reflecting these properties. Morphological analysis of IPF lung tissue revealed that mesenchymal progenitor cells and cells with the characteristics of their progeny comprised the fibrotic reticulum. These data establish that the lungs of patients with IPF contain pathological mesenchymal progenitor cells that are cells of origin for fibrosis-mediating fibroblasts. These fibrogenic mesenchymal progenitors and their progeny represent an unexplored target for novel therapies to interdict fibrosis.