Project description:Ultraviolet B (UVB) irradiation has strong biological effects and modulates the expression of many genes. However, the major biological themes affected by UVB remain poorly understood. This work employs a loop-designed microarray approach and applies a log linear model along with multiple hypotheses testing to identify differentially regulated genes at 4, 8, 16, or 24 hours following UVB irradiation. The most prominent biological themes in lists of differentially regulated gene sets were extracted by functional enrichment analysis using DAVID bioinformatics resources 2007. By this approach, we identify that genes that participate in two prime cellular processes – the ribosome pathway and the oxidative phosphorylation pathway - are persistently activated over a period of 24 hours following UVB irradiation. Microarray results were further verified by both mitochondrial activity assay and real-time PCR analysis. These data suggest that the persistent activation of ribosome and oxidative phosphorylation pathways may have a key role in UVB-induced cellular responses. For the first time, the specific cellular pathways that respond to UVB irradiation consistently and persistently can be delineated confidently using a loop-designed microarray approach and functional bioinformatics analysis. The results of this study offer further insight into UVB-induced stress responses. Keywords: UVB, cDNA microarray, loop design, KEGG pathway
Project description:The goal of this thesis is to study the response of a human keratinocyte cell line (HaCaT cells) after UVB irradiation. In order to develop a system for UV irradiation, we firtstly studied the UV illumination system to find out a stable and reliable condition for UV irradiation experiments. Further, we found out the proper dose of UVB radiation and time points after UVB irradiation by performing MTT assay and trypan blue viability test. According to the results of MTT assay and trypan blue viability test, the cellular activity as well as survival rate of UVB-irradiated cells were in proportion to the radiation doses within a lower UVB dose range. We wanted to find out the possible reasons for this phenomenon by using cDNA microarray. We hope the thesis could be a guide for the following researches, and be useful in the clinical studies about the UV damage. Keywords: dose response and time course Loop-designed microarray experiments were performed in our study. Twenty-one samples are arranges as seven small loops and one large loop, with three and seven microarray slides for each small and large loop, respectively. This set of loop-designed microarray experiment contains one control untreated (non UVB-treated) samples and two UVB-treated samples (one low dose and one high dose UVB-treated) at each time point (total seven time points).
Project description:p53 is activated by DNA damage and oncogenic stimuli to regulate senescence, apoptosis and cell-cycle arrest, which are essential to prevent cancer. Here, we utilized UVB radiation, a potent inducer of DNA damage, p53, apoptosis and skin cancer to investigate the mechanism of CCAAT/enhancer binding protein-β (C/EBPβ) in regulating p53-mediated apoptosis in keratinocytes and to test whether the deletion of C/EBPβ in epidermis can protect mice from UVB-induced skin cancer. UVB-treatment of C/EBPβ skin conditional knockout (CKOβ) mice increased p53 protein levels in epidermis and enhanced p53-dependent apoptotic activity 3-fold compared with UVB-treated control mice. UVB increased C/EBPβ levels through a p53-dependent pathway and stimulated the formation of a C/EBPβ-p53 protein complex; knockdown of C/EBPβ increased p53 protein stability in keratinocytes. These results suggest a p53-C/EBPβ feedback loop, whereby C/EBPβ, a transcriptional target of a p53 pathway, functions as a survival factor by negatively regulating p53 apoptotic activity in response to DNA damage. RNAseq analysis of UVB-treated CKOβ epidermis unexpectedly revealed that type 1 interferon (IFN) pathway was the most highly enriched pathway. Numerous pro-apoptotic interferon stimulated genes were upregulated including some known to enhance p53 apoptosis. Our results indicate that p53 and IFN pathways function together in response to DNA damage to result in the activation of extrinsic apoptosis pathways and caspase 8 cleavage. Last, we observed CKOβ mice were resistant to UVB-induced skin cancer. Our results suggest that C/EBPβ represses apoptosis through keratinocyte autonomous suppression of the type 1 IFN response and p53 to increase cell survival and susceptibility to UVB-induced skin cancer.
Project description:Previous studies showed that SV40 transformed cells have unique DNA damage responses; further inspecting these responses by microarray provides an opportunity to discover transciprtional insights of DNA damage responses after UVB irradiation. This study is used to comapre to GSE7589, our previous study of human normal lung fibroblast after UVB irradiation. We used a loop design in this study, cDNA microarray experiment consisted of eight RNA samples, including UVB-irradiated samples and their corresponding controls of 4 time points after UV irradiation.
Project description:Ultraviolet (UV) radiation is a major melanoma risk factor, yet underlying mechanisms remain poorly understood. Here we introduce a mouse model permitting fluorescence-aided melanocyte imaging and isolation following in vivo UV irradiation. We use expression profiling to show that activated neonatal skin melanocytes isolated following a melanomagenic UVB dose bear a distinct, persistent interferon-response signature, including genes associated with immunoevasion. UVB-induced melanocyte activation, characterized by aberrant growth and migration, was abolished by antibody-mediated systemic blockade of interferon-gamma (IFN-gamma), but not type-I interferons. IFN-gamma was produced by macrophages recruited to neonatal skin by UVB-induced chemokine receptor Ccr2 ligands. Admixed recruited skin macrophages enhanced transplanted melanoma growth by inhibiting apoptosis; notably, IFN-gamma blockade abolished macrophage-associated melanoma growth and survival. IFN-gamma-producing macrophages were identified in 70% of human melanomas examined. Our data reveal an unanticipated role for IFN-gamma in promoting melanocytic cell survival/immunoevasion, and suggest IFN-gamma-R signaling represents a novel therapeutic melanoma target. Biologic replicates of UVA- and UVB-treated mouse melanocytes, as well as untreated mouse melanocytes and mouse keratinocytes, were used to define melanocyte expression signatures associated with UV treatment.
Project description:Skin cancer is the most prevalent cancer in humans, especially in the United States, Australia, and New Zealand. Australia and New Zealand are the two countries with the highest rates of skin cancer in the world, about four times higher than the United States, the United Kingdom and Canada. According to statistics, one American dies of skin cancer every hour. Studies have shown that ultraviolet radiation is the main cause of skin cancer, and ultraviolet rays are mainly divided into UVA, UVB and UVC according to wavelength, UVA and UVB can cause DNA damage, and UVB is the main factor that induces skin cancer. UVB is primarily a direct damage to cellular DNA and generally includes the formation of pyrimidine dimers (CPDs) and 6-4 photoproducts (6-4PPs). UVB can also cause mutations in tumor suppressor genes such as p53, ptch, and ras. These bases the mutation will promote the activation of related signaling pathways, thereby inducing the production of tumors.In this study, we will use gene chip technology to screen out UVB-sensitive genes, and then select the genes of the UVB-sensitive GPCR family from these genes, and further use PCR for verification, so as to identify UVB-sensitive GPCRs, which will provide a basis for further experimental research.
Project description:Use DNA microarray technology to discover transciprtional insights of HaCaT for continuous exposure to ELF-EMF We used a loop design in this study (details in the 'loop_design.tiff' supplementary file), cDNA microarray experiment consisted of ten RNA samples, including ELF-EMF exposed, UVB irradiated (positive control), and sham exposed samples.
Project description:Ultraviolet radiation (UVR) from sunlight is the major effector for skin aging and carcinogenesis. However, genes and pathways altered by solar-simulated UVR (ssUVR), a mixture of UVA and UVB, are not well characterized. Here we report global changes in gene expression as well as associated pathways and upstream transcription factors in human keratinocytes exposed to ssUVR. Human HaCaT keratinocytes were exposed to either a single dose or 5 repetitive doses of ssUVR. Comprehensive analyses of gene expression profiles as well as functional annotation were performed at 24 hours post irradiation. Our results revealed that ssUVR modulated genes with diverse cellular functions in a dose-dependent manner. Gene expression in cells exposed to a single dose of ssUVR differed significantly from those that underwent repetitive exposures. While single ssUVR caused a significant inhibition in genes involved in cell cycle progression, especially G2/M checkpoint and mitotic regulation, repetitive ssUVR lead to extensive changes in genes related to cell signaling and metabolism. We have also identified a panel of ssUVR target genes that exhibited persistent changes in gene expression even at 1 week after irradiation. These results revealed a complex network of transcriptional regulators and pathways that orchestrate the cellular response to ssUVR.
Project description:Ultraviolet (UV) radiation is a major melanoma risk factor, yet underlying mechanisms remain poorly understood. Here we introduce a mouse model permitting fluorescence-aided melanocyte imaging and isolation following in vivo UV irradiation. We use expression profiling to show that activated neonatal skin melanocytes isolated following a melanomagenic UVB dose bear a distinct, persistent interferon-response signature, including genes associated with immunoevasion. UVB-induced melanocyte activation, characterized by aberrant growth and migration, was abolished by antibody-mediated systemic blockade of interferon-gamma (IFN-gamma), but not type-I interferons. IFN-gamma was produced by macrophages recruited to neonatal skin by UVB-induced chemokine receptor Ccr2 ligands. Admixed recruited skin macrophages enhanced transplanted melanoma growth by inhibiting apoptosis; notably, IFN-gamma blockade abolished macrophage-associated melanoma growth and survival. IFN-gamma-producing macrophages were identified in 70% of human melanomas examined. Our data reveal an unanticipated role for IFN-gamma in promoting melanocytic cell survival/immunoevasion, and suggest IFN-gamma-R signaling represents a novel therapeutic melanoma target.