Project description:The TET-family enzymes (TETs) convert methylcytosine to hydroxymethylcytosine, a lately discovered epigenetic modification that can modulate transcription. While recent reports suggest that TETs may play a role in response to oxidative stress, this role remains uncertain. Here we show that Tet1 is sensitive to peroxide and report a global decrease in hydroxymethylcytosine in cells treated with BSO and in the intestinal epithelium of mice lacking the major antioxidant enzymes glutathione peroxidases 1 and 2. Furthermore, genome-wide profiling revealed differentially hydroxymethylated regions in genes involved in responses to oxidative stress. Intriguingly, a considerable proportion of these regions lie in genes encoding microRNAs predicted to target transcripts involved in oxidative stress response. This work thus demonstrates a profound effect of oxidative stress on the hydroxymethylome and opens exciting new avenues of research by highlighting a set of microRNAs that may participate in the prevention or etiology of oxidative-stress-related diseases. Examination of DNA hydroxymethylation landscape in SY5Y cell lines and in intestinal epithelium of mice.
Project description:The TET-family enzymes (TETs) convert methylcytosine to hydroxymethylcytosine, a lately discovered epigenetic modification that can modulate transcription. While recent reports suggest that TETs may play a role in response to oxidative stress, this role remains uncertain. Here we show that Tet1 is sensitive to peroxide and report a global decrease in hydroxymethylcytosine in cells treated with BSO and in the intestinal epithelium of mice lacking the major antioxidant enzymes glutathione peroxidases 1 and 2. Furthermore, genome-wide profiling revealed differentially hydroxymethylated regions in genes involved in responses to oxidative stress. Intriguingly, a considerable proportion of these regions lie in genes encoding microRNAs predicted to target transcripts involved in oxidative stress response. This work thus demonstrates a profound effect of oxidative stress on the hydroxymethylome and opens exciting new avenues of research by highlighting a set of microRNAs that may participate in the prevention or etiology of oxidative-stress-related diseases.
Project description:Ten eleven translocation enzymes (TET1-3) convert 5-methylcytosine (5mC) to 5-hydroxymethylcytosine (5hmC), inducing DNA demethylation and gene regulation. They are often downregulated in cancer, yet the upstream cause of this event remains largely unknown. Here, we show increased TET1 expression in basal-like breast cancer (BLBC), specifically in tumors with low expression of immune markers and low infiltration by immune cells. Furthermore, we identify an anti-correlation between TET1 expression and NF-κB, a major immune regulatory family, in BLBC tissues. In vitro and in vivo, TET1 is downregulated in breast cells upon activation of NF-κB, through binding of p65 to its consensus sequence in the TET1 promoter. Moreover, we uncover genome-wide 5hmC changes related to TET1 regulation in BLBC. Finally, these findings are extended to other cancer types, including melanoma, lung and thyroid cancers. Collectively, our data suggest a novel mode of regulation for TET1, linking TETs and immunity, two major features of cancer.
Project description:The random-pattern skin flap is a crucial technique in reconstructive surgery and flap necrosis caused by ischemia/reperfusion injury is a major postoperative complication. Herein, we investigated the mechanism of mitophagy induced by Melatonin (ML) and its effect on the survival of skin flaps. Our results demonstrated that ML could activate mitophagy, ameliorate oxidative stress and alleviate apoptosis in TBHP-stimulated human umbilical vein endothelial cells in vitro. Inhibiting ML-induced mitophagy considerably abolished its protective effects. Moreover, knockdown of Parkin by siRNA inhibited ML-induced mitophagy, and subsequently exacerbated oxidative stress and apoptosis. Further study demonstrated that inhibition of AMPK reversed these protective effects of ML and downregulated the expression of TFEB. In the vivo study, ML effectively promoted flap survival by activating mitophagy and subsequently ameliorating oxidative stress and mitigating apoptosis. These results established that ML is a potent agent capable for increasing random-pattern skin flap survival by activating Parkin-dependent mitophagy through the AMPK-TFEB signaling pathway.
Project description:Association of the (histone) deacetylase SIRT1 with promoters was assessed to determine putative SIRT1-regulated genes. Based on the observation that the SIRT1 yeast ortholog Sir2 redistributes across the yeast genome in repsonse to genotoxic stress and double strand breaks (DSBs), we investigated the impact of oxidative stress on the chromatin binding pattern of SIRT1. Oxidative stress causes a major change in SIRT1 binding that is accompanied by an inverse H1K26 acetylation pattern. H1K26 was shown to be a direct target for deacetylation by SIRT1. Keywords: ChIP-chip, stress response
Project description:Association of the (histone) deacetylase SIRT1 with promoters was assessed to determine putative SIRT1-regulated genes. Based on the observation that the SIRT1 yeast ortholog Sir2 redistributes across the yeast genome in repsonse to genotoxic stress and double strand breaks (DSBs), we investigated the impact of oxidative stress on the chromatin binding pattern of SIRT1. Oxidative stress causes a major change in SIRT1 binding that is accompanied by an inverse H1K26 acetylation pattern. H1K26 was shown to be a direct target for deacetylation by SIRT1. Keywords: ChIP-chip, stress response ES cells were left untreated or treated with 2 mM H2O2 for 1 hour. Both samples were subjected to ChIP against SIRT1, H1AcK26 or rabbit Ig (one IP per treatment and Ab). Input DNA was labeled with Cy3, IP DNA with Cy5, enrichment over input is reported as 2log.
Project description:The aim of this study is to characterize the systemic stress response (SSR) induced in patients undergoing colorectal cancer (CRC) surgery. The project is a clinical prospective study. Blood samples will be collected from 30 patients on the day before CRC-surgery, and 1, 2, 3 and 10 days after surgery. A specimen from the resected tumor tissue will also be collected and sent for immunohistochemical analysis. Whole blood gene expression profiling will be performed to gain knowledge of the genetic changes in immunological, inflammatory and oxidative stress-related factors initiated by surgery. Peripheral immunological cells, proteins and cytokines will be analysed by FLOW and ELISA methods, and the functional capacity of NK-cells will also be defined for each time point. Furthermore, tumor tissue will be analyzed for invasion of immunological cells. At each time point, the patients will be asked to fill out a validated patient reported outcome measure with questions concerning clinical outcome parameters related to recovery after CRC-surgery