Project description:The Aryl Hydrocarbon Receptor (AHR) is an environmental sensor and an indispensable regulator of epithelial homeostasis. To investigate AHR-mediated gene regulation, we performed a comprehensive transcriptomic and epigenomic analysis using human primary epidermal keratinocytes. Our results showed that AHR activation led to the induction of canonical transcription factors involved in epidermal differentiation as an early response, i.e. Transcription Factor AP-2α (TFAP2A), while epidermal differentiation-related genes, such as filaggrin and keratins, were activated as late responsive genes. The identified AHR-TFAP2A axis and its role in keratinocyte terminal differentiation was confirmed through AHR and TFAP2A knockout using CRISPR/Cas9. Our findings demonstrate that AHR regulates epidermal differentiation through the transient activation of specific transcription factors, such as TFAP2A, in response to environmental cues. The herein identified AHR-TFAP2A axis provides a promising target for the treatment of diseases related to skin barrier dysfunction.
Project description:The Aryl Hydrocarbon Receptor (AHR) is an environmental sensor and an indispensable regulator of epithelial homeostasis. To investigate AHR-mediated gene regulation, we performed a comprehensive transcriptomic and epigenomic analysis using human primary epidermal keratinocytes. Our results showed that AHR activation led to the induction of canonical transcription factors involved in epidermal differentiation as an early response, i.e. Transcription Factor AP-2α (TFAP2A), while epidermal differentiation-related genes, such as filaggrin and keratins, were activated as late responsive genes. The identified AHR-TFAP2A axis and its role in keratinocyte terminal differentiation was confirmed through AHR and TFAP2A knockout using CRISPR/Cas9. Our findings demonstrate that AHR regulates epidermal differentiation through the transient activation of specific transcription factors, such as TFAP2A, in response to environmental cues. The herein identified AHR-TFAP2A axis provides a promising target for the treatment of diseases related to skin barrier dysfunction.
Project description:The AhR is a ligand activated transcription factor that may be important in normal skin physiology. We compared gene expression profiles between AhR Wt and AhR KO primary mouse keratinocyte cultures. We identified 391 genes that were differentially expressed with a 1.5 fold cutoff and p<.05, and identified the AhR as an important regulator of genes involved in normal epidermal differentiation. AhR Wt primary keratinocyte cultures (n=4) were compared with AhR KO primary keratinocyte cultures (n=3)
Project description:The transcriptional program of early embryonic development is tightly regulated by a set of well-defined transcription factors that suppress premature expression of differentiation genes and sustain the pluripotent identity. It is generally accepted that this program can be perturbed by environmental factors such as chemical pollutants, however the precise molecular mechanisms remain unknown. The Aryl Hydrocarbon Receptor (AHR) is a widely expressed nuclear receptor that senses environmental stimuli and modulates target gene expression. Here, we show that ectopic activation of AHR during early differentiation disrupts the differentiation program via the chromatin remodeling complex NuRD. The activated AHR/NuRD complex altered the expression of differentiation-specific genes that control the first two developmental decisions without affecting the pluripotency program. These findings identify a novel mechanism that allows environmental stimuli to disrupt embryonic development through AHR signaling.
Project description:Establishment and maintenance of epithelial architecture are essential for embryonic development and adult physiology. Here, we show that ERK3, a poorly characterized atypical MAPK, regulates epithelial architecture in vertebrates. In Xenopus embryonic epidermal epithelia, ERK3 knockdown impairs adherens and tight junction protein distribution, as well as tight junction barrier function, resulting in epidermal breakdown. Moreover, in human breast epithelial cancer cells, inhibition of ERK3 expression induces thickened epithelia with aberrant adherens and tight junctions. Microarray results suggest an involvement of TFAP2A, a transcription factor important for epithelial gene expression, in ERK3-dependent gene expression changes. TFAP2A knockdown phenocopies ERK3 knockdown in both Xenopus embryos and human cells, and ERK3 is required for full activation of TFAP2A-dependent transcription. Our findings thus reveal that ERK3 regulates epithelial architecture, possibly in cooperation with TFAP2A. We used microarrays to compare the changes in ERK3-dependent gene expression profiles with those in TFAP2A-dependent gene expression profiles in Xenopus laevis embryos.
Project description:The AhR is a ligand activated transcription factor that may be important in normal skin physiology. We compared gene expression profiles between AhR Wt and AhR KO primary mouse keratinocyte cultures. We identified 391 genes that were differentially expressed with a 1.5 fold cutoff and p<.05, and identified the AhR as an important regulator of genes involved in normal epidermal differentiation.
Project description:Atopic dermatitis is increasing worldwide, correlating with air pollutions. Various organic components of pollutants activate transcription factor AhR (aryl-hydrocarbon receptor). We have established AhR-CA mice, whose keratinocytes express constitutive-active AhR, and these mice developed atopic dermatitis-like frequent scratching and allergic inflammation. In this study we performed ChIP-seq analyses and identified keratinocyte-specific AhR target genes, including inflammatory cytokines Tslp and IL33, and neurotrophic factor Artemin. While AhR-CA mice exhibited epidermal hyperinnervation and alloknesis leading to hypersensitivity to pruritus, blockade of Artemin alleviated these phenotypes. AhR-CA mice showed scratching-induced barrier insufficiency and enhanced sensitization to epicutaneously-applied antigens, recapitulating human atopic dermatitis. Consistently, AhR activation and Artemin expression was detected in the epidermis of atopic dermatitis patients and keratinocytes exposed to air pollutants. Thus, AhR in keratinocytes senses the environmental stimuli and responds to them through moderating inflammation. We propose a mechanism in which air pollution induces atopic dermatitis through AhR activation.