Confounding factors in the analysis of the transcriptome response to UV exposure in skin of wild-type and human p53-variant mice
ABSTRACT: An in-vivo experiment with UV-B exposure of the skin of nude, male mice, with and without human-derived p53 variants in their genome to investigate the cellular responses upon UV-induced DNA damage. Essentially, 4 replicate mice were used for each level of UV-exposure. For each mouse a biopsy of the skin was sampled 5-6 times at different recovery time points after UV-pulse exposure, which resulted in paired samples. In total 132 treated and 132 untreated samples were taken from 64 male mice. 264 skin biopsies were taken from 48 mice on 10 timepionts and for 3 different UV-B doses. 3 different genotypes of mice were used, Wild-type (WT; p53+/+), p5372R/72R, and p5372P/72P. Later, it was determined that eight samples came from female mice instead of male mice. Therefore, the eight samples were excluded further analyses (no processed data were generated from these arrays).
Project description:In molecular biology, the design of mechanistic experiments has to be optimized by considering statistical and biological principles. In contrast to statistical principles, biological principles of experimental design are not universally formulated. In an attempt to pinpoint generally acceptable rules, we investigated the importance of determining the optimal ranges of scale of i.e. dose and time in gene expression experiments. We propose a protocol for executing small scale, genome wide, range finding studies, covering a wide range of the potentially relevant part of the design space to find the optimal ranges of experimentation. This protocol is executed and a proof-of-concept is presented, where this approach is tested for both an in-vitro and an in-vivo study that aim to unravel DNA repair mechanisms provoked after UV radiation. We identified four challenges of range finding studies in omics experimentation; (1) the modularity of biological processes, (2) their dynamics, (3) the extent to which end-points indicate biological processes, and (4) the costs associated with the assays, which are all addressed by our approach. 57 skin biopt samples taken from 12 individual mice on 8 timepionts and for 6 different UV-B doses. Per mouse 5 skin biopts were samples in time
Project description:Small scale study to asses the effects of taking multiple skinbiopts from individual mice in time. Results showed no influence on expression levels in time from older samplings on newer samplings. skin biopts from 4 individual mice in taken at 6 points in time
Project description:To test whether there is a photoprotective benefit after different types of suberythemal repetitive UV, a 1.5 MED challenge dose was applied 1 week after the initial 2 weeks of repetitive irradiation. To determine what different mechanisms and/or factors might be involved in physiological pigmentary responses of the skin to different types of UV, we used whole human genome microarrays and immunohistochemical analyses to characterize human skin in situ to examine how melanocyte-specific proteins and paracrine melanogenic factors are regulated by repetitive exposure to suberythemal doses of different types of UV (UVA and/or UVB). Seven volunteers with skin type II-III were irradiated with UVA, UVB or UVA+UVB radiation for 2 weeks (5 times per week, 10 times total) after preliminary determination of their MEDs. A UVA+UVB challenge dose of 1.5X the MED was applied 1 week later. Biopsies were taken before the challenge dose, immediately after the challenge dose, 4 days after the challenge, and 15 weeks after the challenge.
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:To test the hypothesis that different mechanisms and/or factors might be involved in physiological pigmentary responses of the skin to different types of UV, we used whole human genome microarrays and immunohistochemical analyses to characterize human skin in situ to examine how melanocyte-specific proteins and paracrine melanogenic factors are regulated by repetitive exposure to suberythemal doses of different types of UV (UVA, UVB or SSR). Six volunteers with skin type II-III were irradiated with SSR, UVA or UVB radiation for 2 weeks (5 times per week, 10 times total) after preliminary determination of their MEDs. Biopsies were taken 3 days after the last irradiation.
Project description:XPA is required for Nucleotide Excision Repair system, which could function to repair DNA damage induced by the UV. UV damage on the genomic DNA cannot be removed, thus persistence of damage could affect the transcriptional machinary. We used the microarray to investigate the global expression profiles in the XP-A and XP-V cells in the low dose of UVC comparing with fibroblast from healthy person. Human primary fibroblasts were developed from the skin of healthy person and two XP patients (XP-A and XP-V). We evaluated global expression profiles comparing the UVC-exposed (0.5J/m2, 5J/m2) with non-exposed sample.
Project description:To characterize the role of CK1 (encoded by Csnk1a1) in skin physiology, we crossed mice with floxed Csnk1a1 with mice expressing K14CreERT2 to generate mice in which tamoxifen induces the deletion of Csnk1a1 exclusively in keratinocytes (SKO). In addition, we established K14CreERT2 CK1/p53 double-knockout (DKO) to analyze the effect of coablation of both genes. 4-hydroxy-Tamoxifen was applied for 14 days to induce the deletion of CK1 and/or p53 in the epidermis of the mice. In addition, wild type mice where exposed to UVB irradiation to compare the effect of CK1a ablation with the effects of normal UV exposure. In comparison, we analyzed also wild type mice as reference. RNA was obtained from cells derived from mouse ear dorsal-epidermis and tail skin. Subsequently, we performed RNA sequencing and transcriptome analysis.
Project description:Study to optimize our protocol for isolating RNA from skin biopsies from (hairless) SKH mice using different-diameter biopsy punches. Some mice were also treated with UVB radiation to check its effect on RNA yield. 4 mice total: 2 were irradiated with 300J/m2 UVB and 2 were non-irradiated. Post-mortem skin biopsies with 1.5mm, 2.0mm, and 2.5mm diameter punches were taken from the dorsal region.
Project description:The goal of the experiment: To characterize the dynamic gene expression profile of engineered human skin in vitro and after grafting, and compare with expression profile of uninjured human skin. Bioengineered skin substitutes can facilitate wound closure in massively burned patients, but deficiencies limit their outcomes compared to native skin autografts. To identify gene programs associated with their in vivo capabilities and limitations, we extended previous gene expression profile analyses to now compare engineered skin following in vivo grafting to both in vitro maturation and to normal human skin. Cultured skin substitutes were grafted to full-thickness wounds in athymic mice; biopsies for microarray analyses were collected at multiple in vitro and in vivo time points. Over 10,000 transcripts exhibited large-scale expression pattern differences during in vitro and in vivo maturation. Using hierarchical clustering, eleven different expression profile clusters were partitioned based on differential sample type and temporal stage-specific activation or repression. Analyses show that the wound environment exerts a massive influence on gene expression in skin substitutes. For example, in vivo healed skin substitutes gained expression of many native skin-expressed genes, including those associated with epidermal barrier and multiple categories of cell-cell and cell-basement membrane adhesion. In contrast, immunologic, trichogenic, and endothelial gene programs were largely lacking. These analyses suggest important areas to guide further improvement of engineered skin for both increased homology with native skin and enhanced wound healing. Experiment Overall Design: In the study, we hybridized RNA isolated from skin substitutes from days 3, 7, or 14 of in vitro incubation, and 3, 7, 14, 28, 42, or 56 days after transplantation to athymic mice, to Affymetrix Human U133 Plus 2.0 gene chips.
Project description:Whole exome sequencing of 41 melanomas and normal DNA from Braf mutant mice: 15 tumours from UV exposed mice, 15 tumours from non-exposed mice and 11 from UV exposed, sunscreen-protected mice.