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: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:Identification of genes and functions regulated by DDIT3/GADD153/CHOP by transcriptional profiling of cell lines expressing high levels of tamoxifen induced DDIT3.
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.
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:In this study, we demonstrated that deletion of the activating transcription factor 4 (ATF4) resulted in severely impaired HSC expansion in the fetal liver at E12.5 and E15.5. In contrast, generation of the first HSC population in the aorta-gonad-mesonephros region at E11.5 was not significantly affected. Furthermore, the HSC-supporting ability of both endothelial and stromal cells in fetal liver was significantly compromised in the absence of ATF4. Gene profiling using RNA-seq revealed down-regulated expression of a panel of cytokines in ATF4-/- stromal cells, including angiopoietin-like protein 3 (Angptl3) and vascular endothelial growth factor-A (VEGFA). To investigate the molecular pathways of ATF4 in the stromal cells and LSK cells in the fetal liver.
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.