Project description:The role of the skin microbiome in UV-induced immune suppression has been overlooked. We addressed the question of microbial involvement in UV-induced immune suppression by using the standard model of contact hypersensitivity in the presence or absence of the microbiome (in germ-free [GF] and disinfected mice) and found that the microbiome inhibits UV-induced immune suppression. Furthermore, our transcriptome analysis (24 hours after irradiation) showed differential regulation of many genes in the presence or absence of the microbiome, including a predominance of pro-inflammatory cytokines versus immunosuppressive cytokines
Project description:Tanning is a skin protection mechanism against UV radiation. Pigment production initiates hours after exposure, and the mechanism controlling this delay was unknown. Here we reveal a skin UV-protection timer, governed by damped oscillatory dynamics of the melanocyte master regulator, MITF, which after UV exposure, synchronizes regulatory programs, first cell survival and later pigmentation. Remarkably, the same amount of UV dosage resulted in higher pigmentation of human skin when given every-other day compared to daily exposure. Daily UV exposure appears to perturb MITF dynamics, thus re-ordering the survival and pigmentation programs. This demonstrates that the skin is more sensitive to frequency than quantity of UV exposure. Mathematical modeling identified a double negative regulatory loop involving HIF1a and microRNA-148a that regulates MITF dynamics. Our study suggests evolutionary leverage of the UV-protection timer, as it evolved to induce maximum protection with minimum damage for the reduction of skin cancer risk.
Project description:Epigenetic alterations are a driving force of the carcinogenesis process. MicroRNAs play a role in silencing mutated oncogenes, thus defending the cell against the adverse consequences of genotoxic damages induced by environmental pollutants. These processes have been well investigated in lungs; however, although skin is directly exposed to a great variety of environmental pollutants, more research is needed to better understand the effect on cutaneous tissue. Therefore, we investigated microRNA alteration in human skin biopsies exposed to diesel fumes, ozone, and UV light for over 24 h of exposure. UV and ozone-induced microRNA alteration right after exposure, while the peak of their deregulations induced by diesel fumes was reached only at the end of the 24 h. Diesel fumes mainly altered microRNAs involved in the carcinogenesis process, ozone in apoptosis, and UV in DNA repair. Accordingly, each tested pollutant induced a specific pattern of microRNA alteration in skin related to the intrinsic mechanisms activated by the specific pollutant. These alterations, over a short time basis, reflect adaptive events aimed at defending the tissue against damages. Conversely, whenever environmental exposure lasts for a long time, the irreversible alteration of the microRNA machinery results in epigenetic damage contributing to the pathogenesis of inflammation, dysplasia, and cancer induced by environmental pollutants.
Project description:Solar UV represents a ubiquitous environmental physical insult. Thus, to maintain its integrity as an effective barrier, skin must be unusually resistant to cell death. However, UV overexposure causes sunburn1,2 (necrosis and inflammation) and cells that survive harbour damaged DNA, which if not repaired or removed by apoptosis can lead to skin cancer development3-10. CD1d, a transmembrane protein identified in glycolipid antigen presentation11,12 to invariant natural killer T (NKT) cells13,14 is expressed by epithelial cells of most tissues including skin15-17, and shares close homology between humans and mice12. Since CD1d and NKT cells are implicated in regulating UV skin carcinogenesis4,18, we studied susceptibility to UV-induced sunburn in mice either lacking expression of both CD1d and NKT cells or expressing CD1d without NKT cells. Here we show that CD1d, but not NKT cells is necessary for UV to cause sunburn. CD1d causes cells to resist apoptosis in response to UV overexposure as the means to promote cell survival and directs the expression of inflammatory response genes, resulting in tissue destruction and skin inflammation. This previously unknown action of CD1d links the etiology of sunburn to skin cancer. Keywords = CD1d knockout, UV, sunburn, cancer Keywords: other
Project description:We conducted transcript profiling and metabolome profiling induced by UV irradiation in grape berry skin. Transcriptome analysis was carried out with genome-wide microarray and two hundred thirty eight genes were more than 5-fold up-regulated by UV irradiation. The enrichment analysis showed GO terms including stilbene synthase (STS) gene. Moreover, the principal component analysis (PCA) of metabolome analysis showed a compound, identified resveratrol, accumulated in grape berry skin specifically. Our result clearly shows that UV irradiation induced only accumulation of resveratrol and its analogues but did not induce accumulation of the other phenolic compounds.
Project description:Solar radiation is the major source of human exposure to UV radiation, the major carcinogen in skin cancers, by triggering a number of cellular responses that can indirectly or directly induce DNA damage. Skin cells attempt to repair these damages by activating cascades of DNA Damage Response mechanisms to safeguard genome integrity, thereby preventing skin cancers. The role of PPARb - a druggable transcription factor, in the development of UV-dependent skin cancers is not mechanistically elucidated. We have shown previously that PPARb knockout mice are less prone to UV-induced skin cancers. Here, we report on our global transcriptomic analysis revealing that PPARb directly regulates gene expression programs associated with cell cycle and DNA repair pathways in normal human epidermal keratinocytes. We show that in these cells, as well as in malignant human keratinocytes and in human melanoma cells, PPARb controls cellular proliferation and cell cycle progression and its depletion leads to cell cycle arrest. We also show that PPARb controls the response of normal human epidermal keratinocytes to UV-induced DNA damage. PPARb depletion decreases the expression and/or activation of multiple effectors of DNA Damage Response (DDR) pathway and favours the apoptotic response of human keratinocytes to UV irradiation. Our preclinical data of a PDX melanoma model demonstrated that the depletion or inhibition of PPARb delays of blocks tumor formation. Our data suggest that PPARb inhibition can be considered as a therapeutic target for the prevention of UV-induced skin cancers in vulnerable population, by attenuating the DDR and eliminating skin cells with high UV-induced mutational burden.
Project description:Introduction: Diverse microbiotas which have some contributions to gene expression reside in human skin. To identify the protective role of the skin microbiome against UV exposure, proteinprotein interaction (PPI) network analysis is used to assessment gene expression alteration. Methods: A microarray dataset, GEO accession number GSE117359, was considered in this respect. Differential expressed genes (DEGs) in the germ-free (GF) and specific pathogen-free (SPF) groups are analyzed by GEO2R. The top significant DEGs were assigned for network analysis via Cytoscape 3.7.2 and its applications. Results: A total of 28 genes were identified as significant DEGs and the centrality analysis of the network indicated that only one of the seven hub-bottlenecks was from queried genes. The gene ontology analysis of Il6, Cxcl2, Cxcl1, TNF, Il10, Cxcl10, and Mmp9 showed that the crucial genes were highly enriched in the immune system. Conclusion: The skin microbiome plays a significant role in the protection of skin against UV irradiation and the role of TNF and IL6 is prominent in this regard.
Project description:Although excessive exposure to UV is widely recognized as a major factor leading to skin perturbations and cancer, the complex mechanisms underlying inflammatory skin disorders resulting from UV exposure remain incompletely characterized. The nuclear hormone receptor PPARβ/δ is known to control cutaneous repair and UV-induced cancer development. Here, we describe a novel PPARβ/δ-dependent molecular cascade involving TGFβ-1 and miR-21-3p, which is activated in the epidermis in response to UV exposure. We establish that the passenger miRNA miR-21-3p, that we identify as a novel UV-induced miRNA in the epidermis, plays a pro-inflammatory function in keratinocytes, and that its high level of expression in human skin is associated with psoriasis and squamous cell carcinomas. Finally, we provide evidence that inhibition of miR-21-3p reduces UV-induced cutaneous inflammation in ex vivo human skin biopsies, thereby underlining the clinical relevance of miRNA-based topical therapies for cutaneous disorders.
Project description:Although excessive exposure to UV is widely recognized as a major factor leading to skin perturbations and cancer, the complex mechanisms underlying inflammatory skin disorders resulting from UV exposure remain incompletely characterized. The nuclear hormone receptor PPARβ/δ is known to control cutaneous repair and UV-induced cancer development. Here, we describe a novel PPARβ/δ-dependent molecular cascade involving TGFβ-1 and miR-21-3p, which is activated in the epidermis in response to UV exposure. We establish that the passenger miRNA miR-21-3p, that we identify as a novel UV-induced miRNA in the epidermis, plays a pro-inflammatory function in keratinocytes, and that its high level of expression in human skin is associated with psoriasis and squamous cell carcinomas. Finally, we provide evidence that inhibition of miR-21-3p reduces UV-induced cutaneous inflammation in ex vivo human skin biopsies, thereby underlining the clinical relevance of miRNA-based topical therapies for cutaneous disorders.