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: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:Exploring molecular details of carbon utilization trade-offs in galactose-evolved yeast Adaptively evolved yeast mutants on galactose for around 400 generations showed diminished growth and carbon uptake rates on glucose. Genome-scale approaches were applied to characterize the molecular genetic basis of these trade-offs in carbon source utilization. Engineered mutants showing trade-offs in a specific carbon uptake rate between both carbons were used as controls. The transcriptional responses of the evolved mutants were almost identical during growth on both carbon sources. These carbon-independent conserved patterns were clearly observed in specific pathways and genes. Up-regulation of PGM2, a confirmed beneficial genetic change for improving galactose utilization was preserved on both carbons. In addition, HXK1, GLK1 and genes involved in reserve carbohydrate metabolism were up-regulated, while HXK2 was down-regulated. Genes that have a transcription factor binding site for Gis1p, Rph1p, Msn2/4p and Nrg1p were up-regulated. These results indicated changes in the metabolic pathways involved in metabolism of both carbons and in nutrient signaling pathway. The concentration profile of trehalose and glycogen supported these findings. Mutations in RAS2 and ERG5 genes were selected because of their beneficial and neutral effect on galactose utilization, respectively in our previous study. Site-directed mutants containing galactose-beneficial mutations in RAS2 only resulted in a significant decrease in glucose utilization. Integration of all these analyses clearly suggest an antagonistic pleiotropic trade-off in carbon source utilization caused by changes in regulatory region, and we hereby demonstrate how systems biology can be used to gain insight into evolutionary processes at the molecular level. Yeast galactose evolved mutants having improved galactose availability were grown on aerobic batch with glucose as carbon source
Project description:Type 1 interferon (IFN) plays a critical role in early antiviral defense and priming of adaptive immunity by signalling upregulation of host antiviral interferon-stimulated genes (ISGs). Certain stimuli trigger strong activation of IFN regulatory factor 3 (IRF3) and direct upregulation of ISGs in addition to IFN. It remains unclear why some stimuli are stronger activators of IRF3 and how this leads to IFN-independent antiviral protection. We found that UV-inactivated human cytomegalovirus (HCMV) particles triggered an IFN-independent ISG signature that was absent in cells infected with UV-inactivated Sendai virus (SeV) particles. HCMV particles triggered mostly uniform activation of IRF3 and low-level IFN-? production within the population while SeV particles triggered a small fraction of cells producing abundant IFN-?. These findings suggest that population level activation of IRF3 and antiviral protection emerges from a diversity of responses occurring simultaneously in single cells. Moreover, this occurs in the absence of virus replication.
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:This project was conducted by Nitin S. Baliga of the Halobacterium group at the Institute for Systems Biology in collaboration with Jocelyne Diruggiero of University of Maryland. Halobacterium NRC-1 cell pellets were resuspended in an isotonic buffer at a low density, placed on ice and exposed to 200J/m2 of UV-C irradiation, returned to the growth medium and allowed to recover at 42oC in dark (D) or light (L). Total RNA was collected from each sample at 30 minutes (D30 and L30) and 60 minutes (L60 and D60). The control (C) was processed in a manner to identical to L60 except that it did not suffer any UV-C insult. The reference RNA was prepared from an aliquot of the same culture just prior to UV-C irradiation. Therefore the reference was also exposed to initial perturbations prior to UV-C irradiation such as change of growth medium to buffer and change of temperature from 42oC to ice. Keywords = ISB Keywords = Halobacterium NRC-1 Keywords = UV repair Keywords = ultraviolet radiation Keywords = stress response Keywords: other
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:In plants, ultraviolet (UV)-light is an important driver for their growth and natural distribution and is also a valuable tool for manipulating their productivity as well as their biotic interactions. Understanding plant responses to different UV radiation is sparse, especially from a systems biology perspective and particularly for conifers. Here, we evaluated the physiological and transcriptomic responses to the short-term application of high-irradiance UV-B and UV-C waves on Pinus tabuliformis Carr., a major conifer in Northern China. By undertaking time-ordered gene co-expression network analyses and network comparisons incorporating physiological traits and gene expression variation, we uncovered communalities but also differences in P. tabuliformis responses to UV-B and UV-C. Both types of spectral bands caused a significant inhibition of photosynthesis and conversely improvement of antioxidant capacity, flavonoid production and signaling pathways related to stress resistance, indicating a clear switch from predominantly primary metabolism to enhanced defensive metabolism in pine. We isolated distinct subnetworks for photoreceptor-mediated signal transduction, maximum quantum efficiency of photosystem II (Fv/Fm) regulation and flavonoid biosynthesis in response to UV-B and UV-C irradiation. From these subnetworks, we further identified phototropins as potential important elements in both UV-B and UV-C signaling and, for the first time, reveal peptide hormones possibly involved in promoting flavonoid biosynthesis against UV-B, while these hormones seem not to be implicated in defense against UV-C exposure. The present study employed an effective strategy for disentangling the complex physiological and genetic regulatory mechanisms in a non-model plant species, and thus, provides a suitable reference for future functional evaluations and artificial UV-light mediated growing strategies in plant production.