Project description:Cockayne syndrome is an inherited premature aging syndrome associated with developmental and neurological disorders. Mutations in the genomic locus encoding CSB are associated with 80% Cockayne syndrome cases. CSB is invovled in relieving UV-induced and oxidative stree. To gain more insights into the fucntion of CSB under these stress, we use ChIP-seq to determine the genomic localization of CSB 1 hour after UV irradiation and menadione treatment. Genomic localization of CSB and remodeling deficient CSBâN1
Project description:Cockayne syndrome (CS) is an inherited neurodevelopmental disorder with progeroid features. Although the genes responsible for CS have been implicated in a variety of DNA repair- and transcription-related pathways, the nature of the molecular defect in CS remains mysterious. We sought to define this defect by expression analysis of cells lacking functional CSB, a SWI/SNF-like ATPase that is responsible for most CS cases.
Project description:Cockayne syndrome is an inherited premature aging syndrome associated with developmental and neurological disorders. Mutations in the genomic locus encoding CSB are associated with 80% Cockayne syndrome cases. CSB is invovled in relieving UV-induced and oxidative stree. To gain more insights into the fucntion of CSB under these stress, we use ChIP-seq to determine the genomic localization of CSB 1 hour after UV irradiation and menadione treatment.
Project description:Maintenance of genetic integrity is essential for survival of all organisms. Activating transcription factor 3 (ATF3) is a member of the c-AMP response element binding (CREB)/ATF family of transcription factors, and is highly inducible by various stress conditions including DNA damage. However, downstream targets and molecular basis underlying pleiotropic effects of ATF3 on the cell fate have been largely unknown. To identify ATF3 targets in the human genome, we carried out chromatin immunoprecipitation-microarray (ChiP-on-chip) and knockdown-expression profiling analysis using two models where ATF3 was either transiently induced or constitutively expressed. We show that ATF3 binds to an unexpectedly large number of targets; 5,984 promoters in HCT116 cells treated with an alkylating agene methyl methanesulfonate (MMS) and 1,423 promoters in LNCaP cells constitutively expressing ATF3. Importantly, targets of MMS-induced ATF3 are highly enriched not only for CREB/ATF motifs but also for binding sites of several stress sensors including DDIT3/CHOP, Egr1, and c-Ets which are concomitantly induced by MMS. Stress-induced ATF3 affects broad but select biological processes including cell cycle, cell death, adhesion, biosynthesis, and receptor signaling pathways. In addition, ATF3 binds to as many as 40% of the p53 targets and preferentially enhances MMS-induced activation of proapoptotic genes such as DR4, DR5, and PUMA, consistent with the proapoptotic effect of ATF3. These data shed new light on the co-regulatory function of ATF3 in the stress-induced transcription factor network. The comprehensive list of genomic targets of ATF3 will facilitate further understanding the role of ATF3 in determining life and death of cells under both physiological and tumour-associated stress conditions. Maintenance of genetic integrity is fundamental to survival of all organisms. DNA damage can be caused by various agents in environment and elicits complex responses in the cell. ATF3 is one of the transcription factors activated by various stress conditions including DNA damage, and has been shown to have pleiotropic effects on life and death of cells depending on the context of experimental conditions. It has been largely unknown, however, which genes and pathways are regulated by stress-induced ATF3. Here we attempted to answer this question by chromatin immunoprecipitation-microarray analysis of downstream targets of ATF3. We show that ATF3 binds to an unexpectedly large number of promoters (nearly 6,000) in a human colorectal cancer cell lineHCT116 treated with an alkylating agent methyl methanesulfonate. Interestingly, the ATF3 targets are highly enriched for binding sites of other stress sensors shedding light on a transcriptional co-regulatory network of DNA damage response. We further show that ATF3 regulates expression of genes in select biological processes including cell cycle, cell death, adhesion, metabolism, signal transduction, and the p53 pathway. The comprehensive list of ATF3 targets provides new insight into a highly inter-connected network of stress-induced transcription factors around ATF3. ChIP-chip samples: Comparison of ATF3-IP and whole genome DNA (control) Gene expression samples: HCT116 cells pre-transfected with either control siRNA or ATF3 knockdown siRNA and stimulated by methyl methanesulfonate (MMS) for 0, 6, 12, and 24 hours
Project description:Cockayne syndrome is a segmental progeria most often caused by mutations in the CSB gene encoding a SWI/SNF-like ATPase required for transcription-coupled DNA repair (TCR). Over 43 Mya before marmosets diverged from humans, a piggyBac3 (PGBD3) transposable element integrated into intron 5 of the CSB gene. As a result, primate CSB genes now generate both CSB protein and a conserved CSB-PGBD3 fusion protein in which the first 5 exons of CSB are alternatively spliced to the PGBD3 transposase. We show by microarray analysis that expression of the fusion protein alone in CSB-null UV-sensitive syndrome cells (UVSS1KO) cells induces an interferon-like response that resembles both the innate antiviral response and the prolonged interferon response normally maintained by unphosphorylated STAT1 (U-STAT1); moreover, as might be expected based on conservation of the fusion protein, this potentially cytotoxic interferon-like response is largely reversed by coexpression of functional CSB protein. Interestingly, expression of CSB and the CSB-PGBD3 fusion protein together, but neither alone, upregulates the insulin growth factor binding protein IGFBP5 and downregulates IGFBP7, suggesting that the fusion protein may also confer a metabolic advantage, perhaps in the presence of DNA damage. Finally, we show that the fusion protein binds in vitro to members of a dispersed family of 900 internally deleted piggyBac elements known as MER85s, providing a potential mechanism by which the fusion protein could exert widespread effects on gene expression. Our data suggest that the CSB-PGBD3 fusion protein is important in both health and disease, and could play a role in Cockayne syndrome. 12 samples total; 4 gene expression conditions in triplicate; 1 condition is a tag-only negative control
Project description:Integration of metabolic, stress and immune responses plays a fundamental role during animal development to maintain energy homeostasis while ensuring growth and proper developmental timing. Perturbation of metabolic and immune signaling circuits has detrimental consequences to animal development including growth retardation, organ malfunction and emergence of the metabolic syndrome. Here, we demonstrate that the Drosophila basic region-leucine zipper (bZIP) protein, Activating transcription factor 3 (Atf3), safeguards a balance of metabolic and immune system responses during fly development. Loss of Atf3 function results in lethality during late-larval and pupal stages. Atf3-deficient larvae exhibit phenotypes resembling the metabolic syndrome in mammals. Excessive accumulation of lipids in the larval fat body and gut is accompanied by altered expression of genes involved in lipid metabolism. Moreover, the fat body of atf3 mutants becomes infiltrated by hemocytes. The major pro-inflammatory pathways signaling through JNK and Imd are hyperactivated in atf3 mutants, causing ectopic expression of antimicrobial peptide genes. Suppression of the immune response, achieved by reducing the gene dose of the transcription factors FOXO or NF-kappaB/Relish, significantly improves lipid metabolism and normalizes gene expression profile of atf3 mutants. In addition, heterozygosity of relish partially rescues lethality of the atf3 mutants. Our data thus identify Atf3 as an essential player that links metabolic and immune system homeostasis during animal development. Examination of mRNA levels from four genotypes of male, 3rd instar Drosophila melanogaster larvae. mRNA levels from four genotypes relative to y w control were determined using two biological replicates per genotype. Genome build: BDGP R5/dm3, April 2006
Project description:The rare genetic disease Cockayne syndrome (CS) results in mutations in CSA and CSB. Upon UV irradiation, RNA synthesis was arrested: RNA-seq showed 70% of down-regulated genes in common between CSA and CSB deficient cells. ATF3, the product of an immediate early gene was overexpressed and bound to its CRE/ATF site to inhibit its responsive genes. ChIP experiments showed that CSA/CUL4A/DDB1 together with CSB and MDM2, target ATF3. In vivo and in vitro experiments showed that ATF3 was ubiquitilated by a concerted action of CSA and MDM2 ubiquitin-ligases and was further eliminated by the proteasome concomitantly with the recruitment of RNA polymerase II to restart transcription. In CS cells, dysfunctional CSA or CSB were unable to assemble the ubiquitin/proteasome complex, thereby maintaining the ATF3-dependent transcription arrested. Though, in addition to their function in DNA repair, CSA and CSB might thus regulate the timing of DNA binding factors on its specific target site via the ubiquitin/proteasome machinery.
Project description:The rare genetic disease Cockayne syndrome (CS) results in mutations in CSA and CSB. Upon UV irradiation, RNA synthesis was arrested: RNA-seq showed 70% of down-regulated genes in common between CSA and CSB deficient cells. ATF3, the product of an immediate early gene was overexpressed and bound to its CRE/ATF site to inhibit its responsive genes. ChIP experiments showed that CSA/CUL4A/DDB1 together with CSB and MDM2, target ATF3. In vivo and in vitro experiments showed that ATF3 was ubiquitilated by a concerted action of CSA and MDM2 ubiquitin-ligases and was further eliminated by the proteasome concomitantly with the recruitment of RNA polymerase II to restart transcription. In CS cells, dysfunctional CSA or CSB were unable to assemble the ubiquitin/proteasome complex, thereby maintaining the ATF3-dependent transcription arrested. Though, in addition to their function in DNA repair, CSA and CSB might thus regulate the timing of DNA binding factors on its specific target site via the ubiquitin/proteasome machinery.
Project description:Cockayne syndrome (CS) is an inherited neurodevelopmental disorder with progeroid features. Although the genes responsible for CS have been implicated in a variety of DNA repair- and transcription-related pathways, the nature of the molecular defect in CS remains mysterious. We sought to define this defect by expression analysis of cells lacking functional CSB, a SWI/SNF-like ATPase that is responsible for most CS cases. Keywords: primary disease rescue
Project description:Cockayne syndrome B (CSB) protein is a member of the SWI/SNF family and has DNA-dependent ATPase and ATP-dependent chromatin remodeling activities. The CSB protein is missing or altered in CS-B cells. CS-B cells are hypersensitive to UV light and defective in transcription-coupled DNA repair (TCR). TCR efficiently removes a variety of lesions from the transcribed strand of active genes. It has been shown that lesions specifically in the transcribed strand of active genes trigger the induction of apoptosis following UV irradiation. Several DNA damage signaling cascades, including the ATR/Chk1, p38 kinase, p53, and jun N-terminal kinase pathways are activated following UV irradiation. However, the role of TCR in cellular global transcriptional responses to UV irradiation remains to be elucidated. Using oligonucleotide microarray technology, we analyzed the time course of responses of CS-B cells (CS-B) and CS-B cells complemented with wild-type CSB cDNA (CS-B wt). Keywords: UV response, time course, disease state analysis