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:Cells rapidly and extensively remodel their transcriptome in response to stress to restore homeostasis, but the underlying mechanisms are not fully understood. Here we characterize the dynamic changes in transcriptome, epigenetics, and 3D genome organization during the integrated stress response (ISR). ISR induction triggers widespread transcriptional changes within 6 hours, coinciding with increased binding of ATF4, a key transcriptional effector. Notably, ATF4 binds to hundreds of genes even under non-stress conditions, priming them for stronger activation upon stress. The transcriptional changes during ISR do not rely on increased H3K27 acetylation, chromatin accessibility, or rewired enhancer-promoter looping. Instead, ATF4-mediated gene activation is linked to the redistribution of CEBPγ from non-ATF4 sites to a subset of ATF4-bound regions, likely by forming an ATF4/CEBPγ heterodimer. CEBPγ preferentially targets the sites pre-occupied by ATF4, as well as genomic regions exhibiting a unique higher-order chromatin structure signature. Thus, the transcriptional responses during ISR are largely pre-wired by intrinsic chromatin properties. These findings provide novel insights into transcriptional remodeling during ISR with broader implications for other stress responses. Through the IP-MS experiments, we determined the proteins that interacted with ATF4 and their change during ISR.
Project description:Liver zonation remains a critical aspect of understanding its response to acute injury. This study investigates the impact of acetaminophen-induced acute liver injury on zonal heterogeneity during early phases of injury. Through Ki67 staining, we observed a transient pause in proliferation specifically among mid-lobular hepatocytes during the initiation phase. Using spatial transcriptomics, immunostaining, and in vivo assays, we elucidated that mid-lobular hepatocytes upregulate the Atf4-Ddit3 axis, offering temporary protection at the cost of reduced proliferation mediated by Btg2. Our findings underscore the unique zonal metabolism of acetaminophen as a determinant of differential tissue responses across lobular regions. This study highlights how distinct liver zones exhibit varied responses during the early stages of acute injury, with mid-lobular hepatocytes showing an integrated stress response characterized by protective mechanisms that temporarily suppress proliferation.
Project description:Liver zonation remains a critical aspect of understanding its response to acute injury. This study investigates the impact of acetaminophen-induced acute liver injury on zonal heterogeneity during early phases of injury. Through Ki67 staining, we observed a transient pause in proliferation specifically among mid-lobular hepatocytes during the initiation phase. Using spatial transcriptomics, immunostaining, and in vivo assays, we elucidated that mid-lobular hepatocytes upregulate the Atf4-Ddit3 axis, offering temporary protection at the cost of reduced proliferation mediated by Btg2. Our findings underscore the unique zonal metabolism of acetaminophen as a determinant of differential tissue responses across lobular regions. This study highlights how distinct liver zones exhibit varied responses during the early stages of acute injury, with mid-lobular hepatocytes showing an integrated stress response characterized by protective mechanisms that temporarily suppress proliferation.
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.
