Project description:We used AAV to overexpress ATF4 in murine cardiomyocytes in vivo and perfomred bioChIP-Seq to profile the chromatin occupancy of the exogenous protein
Project description:We report the direct target genes of ATF4 and CHOP in response to endoplasim reticulum stress through next generation sequencing. By obtaining genowide sequence from chromatin immunoprecipitated DNA with anti-CHOP and anit-ATF4, we identified direct binding sites of ATF4 and CHOP in promoter regions of their target genes in mouse embrynic fibroblasts (MEFs) in response to ER stress. In addition, we obtained list of genes which are differentially regulated in Atf4 or Chop-deficient MEFs compared to the wild-type MEFs in response to ER stress. We found that genes related with unfolded protein response and protein synthesis were directly regulated by ATF4 and CHOP. Through this observation, we conclude that main role of ATF4 and CHOP as transcription factors is to enhance mRNA translation in respone to ER stress. This sutdy provide new insight of genetic network of ATF4 and CHOP in response to ER stress. For ChIP-seq, Chop+/+ and Chop-/- MEFs were treated with Tunicamycin, N-glycosylation inhibitor, to induce ER stress for 8hr. Atf4+/+ and Atf4-/- MEFs were also treated same condition for ChIP-Seq. For mRNA-seq, wild-type, Atf4-/-, and Chop-/- MEFs were treated with tunicamycin for 8hr for experiments.
Project description:To evaluate the effect of CG methylation on DNA binding of sequence-specific B-ZIP transcription factors (TFs) in a high-throughput manner, we enzymatically methylated the cytosine in the CG dinucleotide on protein binding microarrays. Using this novel technology, we show that CG methylation enhanced binding for CEBPA and CEBPB and inhibited binding for CREB, ATF4, JUN, JUND, CEBPD and CEBPG. The CEBPB|ATF4 heterodimer bound a novel motif CGAT|GCAA 10-fold better when methylated. EMSA confirmed these results. CEBPB ChIP-seq data using primary female mouse dermal fibroblasts with 50X methylome coverage for each strand indicate that the methylated sequences well-bound on the arrays are also bound in vivo. CEBPB bound 39% of the methylated canonical 10-mers ATTGC|GCAAT in the mouse genome. After ATF4 protein induction by thapsigargin which results in ER stress, CEBPB binds methylated CGAT|GCAA in vivo, recapitulating what was observed on the arrays. mRNA-seq of primary female mouse dermal fibroblasts with and without thapsigargin identified differentially expressed genes. Genes that are commonly bound by CEBPB and ATF4 to TGAT|GCAA (the best-bound 8-mer in the array) at the promoters were highly expressed and up-regulated or remained unchanged in the thapsigargin treated primary female mouse dermal fibroblasts. RNA-Seq: Examination of whole genome transcriptome profiles (RNA-seq) of primary mouse dermal fibroblasts with and without Thapsigargin treatment ChIP-Seq: Examination of transcription factor binding in dermal fibroblasts with and without Thapsigargin teratment BS-Seq: Determination of whole genome DNA methylation profiles (BS-seq) of primary mouse dermal fibroblasts
Project description:To evaluate the effect of CG methylation on DNA binding of sequence-specific B-ZIP transcription factors (TFs) in a high-throughput manner, we enzymatically methylated the cytosine in the CG dinucleotide on protein binding microarrays. Two Agilent DNA array designs were used. One contained 40,000 features using de Bruijn sequences where each 8-mer occurs 32 times in various positions in the DNA sequence. The second contained 180,000 features with each CG containing 8-mer present three times. The first design was better for identification of binding motifs, while the second was better for quantification. Using this novel technology, we show that CG methylation enhanced binding for CEBPA and CEBPB and inhibited binding for CREB, ATF4, JUN, JUND, CEBPD and CEBPG. The CEBPB|ATF4 heterodimer bound a novel motif CGAT|GCAA 10-fold better when methylated. EMSA confirmed these results. CEBPB ChIP-seq data using primary female mouse dermal fibroblasts with 50X methylome coverage for each strand indicate that the methylated sequences well-bound on the arrays are also bound in vivo. CEBPB bound 39% of the methylated canonical 10-mers ATTGC|GCAAT in the mouse genome. After ATF4 protein induction by thapsigargin which results in ER stress, CEBPB binds methylated CGAT|GCAA in vivo, recapitulating what was observed on the arrays. This methodology can be used to identify new methylated DNA sequences preferentially bound by TF, which may be functional in vivo. To evaluate the effect of CG methylation on DNA binding of sequence-specific B-ZIP transcription factors (TFs) in a high-throughput manner, we enzymatically methylated the cytosine in the CG dinucleotide on protein binding microarrays. Two Agilent DNA array designs were used. One contained 40,000 features using de Bruijn sequences where each 8-mer occurs 32 times in various positions in the DNA sequence. The second contained 180,000 features with each CG containing 8-mer present three times. The first design was better for identification of binding motifs, while the second was better for quantification. Using this novel technology, we show that CG methylation enhanced binding for CEBPA and CEBPB and inhibited binding for CREB, ATF4, JUN, JUND, CEBPD and CEBPG. The CEBPB|ATF4 heterodimer bound a novel motif CGAT|GCAA 10-fold better when methylated. EMSA confirmed these results. CEBPB ChIP-seq data using primary female mouse dermal fibroblasts with 50X methylome coverage for each strand indicate that the methylated sequences well-bound on the arrays are also bound in vivo. CEBPB bound 39% of the methylated canonical 10-mers ATTGC|GCAAT in the mouse genome. After ATF4 protein induction by thapsigargin which results in ER stress, CEBPB binds methylated CGAT|GCAA in vivo, recapitulating what was observed on the arrays. This methodology can be used to identify new methylated DNA sequences preferentially bound by TF, which may be functional in vivo. Protein binding microarray (PBM) experiments were performed for a set of 8 mouse B-ZIP homodimers and one hetrodimer transcription factors. Briefly, the PBMs involved binding GST-tagged DNA-binding proteins to double-stranded and methylated or unmethylated 44K Agilent microarrays, containing a DeBruijn sequence design, in order to determine their sequence preferences. Details of the PBM protocol are described in Berger et al., Nature Biotechnology 2006.
Project description:Cardiac development involves large-scale rearrangements of the proteome. How the developing cardiac cells maintain the integrity of the proteome during the rapid lineage transition remains unclear. Here we show that proteotoxic stress visualized by the misfolded protein aggregates appears during early cardiac differentiation of human embryonic stem cells (hESCs) and is resolved by activation of the PERK branch of the unfolded protein response (UPR). PERK depletion increases misfolded protein accumulation, leading to pluripotency exit defect and impaired mesendoderm specification of hESCs. Mechanistically, we found that PERK safeguards cardiogenesis through its conserved downstream effector ATF4, which subsequently activates a novel transcriptional target WARS1, to cope with the differentiation-induced proteotoxic stress. Our results indicate that protein quality control represents a previously unrecognized core component of the cardiogenic regulatory network. Broadly, these findings provide a framework for understanding how UPR is integrated into the developmental program by activating the PERK-ATF4-WARS1 axis.
Project description:Activating Transcription Factor 4 (ATF4) is a transcription factor induced by the integrated stress response (ISR). This experiment is a genome-wide profiling of ATF4-dependent RNA expression in human HAP-1 cells. HAP-1 is a near-haploid human cell line that was derived from KBM-7 cells isolated from a patient with Chronic Myelogenous Leukemia. We analyzed WT and ATF4 KO cells. We induced ATF4 expression by mimicking amino acid starvation with the drug histidinol. RNA expression profiles were generated for WT and ATF4 KO HAP1 cells. ATF4 genes were mutated using Cas9 genome editing technology. Amino acid starvation was mimicked by treating WT and ATF4 KO cells with 2 mM histidinol for 24 hours, which increases ATF4 expression.
Project description:Oxidative stress is pathogenic in neurological diseases including stroke. The identity of oxidative stress-inducible transcription factors and their role(s) in propagating the death cascade are poorly understood. Microarray analysis of neurons undergoing oxidative stress showed significant induction of prodeath genes. These genes have been shown to be regulated by the bZip transcription factor, ATF4. ATF4 protein localized to the promoter of a putative death gene in neurons in vitro and in vivo. Germline deletion of ATF4 in neurons resulted in a reduction in oxidative stress-induced gene expression and resistance to oxidative death. ATF4 knockout mice experienced significantly smaller infarcts and improved behavioral recovery as compared to wild-type mice subjected to the same reductions in blood flow in a rodent model of stroke. ATF4 modulates an early, upstream event in the death pathway, as resistance to oxidative death by ATF4 deletion was associated with decreased consumption of the antioxidant glutathione. Restoration of ATF4 protein in knockout neurons was sufficient to restore sensitivity to oxidative death and to reaccelerate loss of glutathione. Together, these findings establish ATF4 as a redox-regulated, pro-death transcriptional activator in the nervous system that propagates death responses to oxidative stress in vitro and to stroke in vivo. Keywords: ATF4, oxidative stress, gene expression, neuroprotection, stroke WT and ATF4 KO embryonic neurons were studied. Untreated neurons (no=8 per genotype) and neurons challenged with oxidative stress with the glutamate homolog homocysteate (HCA, no=4 per genotype) were studied, for a total of 24 samples.