Project description:AP1 transcription factor family members: activating transcription factor 2 (ATF2) and activating transcription factor 7 (ATF7) have highly redundant functions due to homology and hence overlapping DNA-binding sites. The role of these transcription factors in intestinal epithelial homeostasis and repair has not been critically examined. Here, by using an intestine-specific deletion of ATF2 combined with body wide deletion of ATF7 in mice we assess the role of these proteins during intestinal homeostasis and repair after inflammation.
Project description:Background & aimsActivation factor-1 transcription factor family members activating transcription factors 2 and 7 (ATF2 and ATF7) have highly redundant functions owing to highly homologous DNA binding sites. Their role in intestinal epithelial homeostasis and repair is unknown. Here, we assessed the role of these proteins in these conditions in an intestine-specific mouse model.MethodsWe performed in vivo and ex vivo experiments using Villin-CreERT2Atf2fl/flAtf7ko/ko mice. We investigated the effects of intestinal epithelium-specific deletion of the Atf2 DNA binding region in Atf7-/- mice on cellular proliferation, differentiation, apoptosis, and epithelial barrier function under homeostatic conditions. Subsequently, we exposed mice to 2% dextran sulfate sodium (DSS) for 7 days and 12 Gy whole-body irradiation and assessed the response to epithelial damage.ResultsActivating phosphorylation of ATF2 and ATF7 was detected mainly in the crypts of the small intestine and the lower crypt region of the colonic epithelium. Under homeostatic conditions, no major phenotypic changes were detectable in the intestine of ATF mutant mice. However, on DSS exposure or whole-body irradiation, the intestinal epithelium showed a clearly impaired regenerative response. Mutant mice developed severe ulceration and inflammation associated with increased epithelial apoptosis on DSS exposure and were less able to regenerate colonic crypts on irradiation. In vitro, organoids derived from double-mutant epithelium had a growth disadvantage compared with wild-type organoids, impaired wound healing capacity in scratch assay, and increased sensitivity to tumor necrosis factor-α-induced damage.ConclusionsATF2 and ATF7 are dispensable for epithelial homeostasis, but are required to maintain epithelial regenerative capacity and protect against cell death during intestinal epithelial damage and repair.
Project description:Inflammatory caspases are essential effectors of inflammation and cell death. Here, we investigated their roles in colitis and colorectal cancer and report a bimodal regulation of intestinal homeostasis, inflammation and tumorigenesis by caspases-1 and -12. Casp1-/- mice exhibited defects in mucosal tissue repair and succumbed rapidly after dextran sulfate sodium (DSS) administration. This phenotype was rescued by administration of exogenous interleukin-18 and was partially reproduced in mice deficient in the inflammasome adaptor ASC. Casp12-/- mice, in which the inflammasome is derepressed, were resistant to acute colitis and showed signs of enhanced repair. Together with their increased inflammatory response, the enhanced repair response of Casp12-/- mice rendered them more susceptible to colorectal cancer induced by azoxymethane (AOM)+DSS. Taken together, our results indicate that the inflammatory caspases are critical in the induction of inflammation in the gut following injury, which is necessary for tissue repair and maintenance of immune tolerance. Total RNA obtained from isolated tumors or normal colon tissue from wild type and caspase-12 deficient mice were compared.
Project description:Immunological memory is generally thought to be mediated exclusively by lymphocytes such as memory T and B cells. However, enhanced innate immune responses caused by a previous infection increase protection against reinfection suggesting the presence of innate immunological memory. Here, we describe 3,811 ATF7 binding sites in mouse peritoneal macrophages, and 95% of the ATF7 signals in wild-type macrophages are lost in ATF7 knockout macrophages. ATF7 suppresses a group of innate-immunity genes in macrophage by recruiting H3K9 dimethyltransferase G9a. TLR ligands induce ATF7 phosphorylation, leading to release of ATF7 from chromatin and reduction in H3K9me2 level. Partially disrupted chromatin structure and increased basal expression on target genes are maintained for a long period, increasing resistance pathogens. Therefore we speculate ATF7 is important factor in controlling innate immunological memory. This series contains one set of whole genome ChIP-chip data and 2 sets of promoter array ChIP-chip data. For all sample, we use three IP .CEL files and three WCE .CEL files (they are triplicated experiments) to make one profile.
Project description:Activation transcription factor 2 (ATF2), a member of the ATF/CREB family of transcription factors, is implicated in a broad spectrum of cancer-related biological functions, such as cell proliferation, apoptosis and DNA repair. Growing evidence indicates ATF2 act as an oncogene or a tumor suppressor in different cancer types depending on its expression level and subcellular localization. In this study, RNA-seq and ChIP-seq were performed for identification of genome-wide DNA binding sites and potential transcription targets for ATF2.
Project description:Activation transcription factor 2 (ATF2), a member of the ATF/CREB family of transcription factors, is implicated in a broad spectrum of cancer-related biological functions, such as cell proliferation, apoptosis and DNA repair. Growing evidence indicates ATF2 act as an oncogene or a tumor suppressor in different cancer types depending on its expression level and subcellular localization. In this study, RNA-seq and ChIP-seq were performed for identification of genome-wide DNA binding sites and potential transcription targets for ATF2.
Project description:Immunological memory is generally thought to be mediated exclusively by lymphocytes such as memory T and B cells. However, enhanced innate immune responses caused by a previous infection increase protection against reinfection suggesting the presence of innate immunological memory. Here, we describe expression profile of peritoneal macrophages from wild-type mice pre-administrated with TLR ligands or from ATF7 knockout mice. ATF7 suppresses a group of innate-immunity genes in macrophage by recruiting H3K9 dimethyltransferase G9a. TLR ligands induce ATF7 phosphorylation, leading to release of ATF7 from chromatin and reduction in H3K9me2 level. Partially disrupted chromatin structure and increased basal expression on target genes are maintained for a long period, increasing resistance pathogens. Therefore we speculate ATF7 is important factor in controlling innate immunological memory. This series contains seven sets of exression array data. For all sample, we use four CEL files generated by four biological-independent experiments.
Project description:Alternative splicing and post-translational modifications are processes that give rise to the complexity of the proteome. The nuclear ATF7 and ATF2 (activating transcription factor) are structurally homologous leucine zipper transcription factors encoded by distinct genes. Stress and growth factors activate ATF2 and ATF7 mainly via sequential phosphorylation of two conserved threonine residues in their activation domain. Distinct protein kinases, among which mitogen-activated protein kinases (MAPK), phosphorylate ATF2 and ATF7 first on Thr71/Thr53 and next on Thr69/Thr51 residues respectively, resulting in transcriptional activation. Here, we identify and characterize a cytoplasmic alternatively spliced isoform of ATF7. This variant, named ATF7-4, inhibits both ATF2 and ATF7 transcriptional activities by impairing the first phosphorylation event on Thr71/Thr53 residues. ATF7-4 indeed sequesters the Thr53-phosphorylating kinase in the cytoplasm. Upon stimulus-induced phosphorylation, ATF7-4 is poly-ubiquitinated and degraded, enabling the release of the kinase and ATF7/ATF2 activation. Our data therefore conclusively establish that ATF7-4 is an important cytoplasmic negative regulator of ATF7 and ATF2 transcription factors.
Project description:Characterized by striking metastatic propensity and chemoresistance, melanoma is among the most lethal cutaneous malignancies. The transcription factor ATF2 was shown to elicit oncogenic activities in melanoma, and its inhibition attenuates melanoma development. Here, a mouse model engineered to express a transcriptionally inactive form of Atf2 (Atf2?8,9) was found to be sufficient to induce nevi formation and, when crossed with BrafV600E animals, to promote melanoma development. The cross of Atf2?8,9 with BrafV600E;Pten-/- mice augmented pigmentation, tumorigenicity, and metastasis. Similar to mouse Atf2?8,9, the human ATF2 splice variant 5 enhanced growth and migration capacity of cultured melanoma and immortalized melanocytes. Induced Melan-A, CXCL9, S100A8, CCR7 expression, seen in Atf2?8,9-driven tumors associate with their enhanced pigmentation, immune infiltration and propensity to metastasize. Notably, elevated ATF2SV5 expression in melanoma specimens coincided with poor prognosis. The gain-of-function activity elicited by the truncated ATF2 form offers unexpected insight into mechanisms underlying melanoma development and progression.
Project description:Characterized by striking metastatic propensity and chemoresistance, melanoma is among the most lethal cutaneous malignancies. The transcription factor ATF2 was shown to elicit oncogenic activities in melanoma, and its inhibition attenuates melanoma development. Here, a mouse model engineered to express a transcriptionally inactive form of Atf2 (Atf2?8,9) was found to be sufficient to induce nevi formation and, when crossed with BrafV600E animals, to promote melanoma development. The cross of Atf2?8,9 with BrafV600E;Pten-/- mice augmented pigmentation, tumorigenicity, and metastasis. Similar to mouse Atf2?8,9, the human ATF2 splice variant 5 enhanced growth and migration capacity of cultured melanoma and immortalized melanocytes. Induced Melan-A, CXCL9, S100A8, CCR7 expression, seen in Atf2?8,9-driven tumors associate with their enhanced pigmentation, immune infiltration and propensity to metastasize. Notably, elevated ATF2SV5 expression in melanoma specimens coincided with poor prognosis. The gain-of-function activity elicited by the truncated ATF2 form offers unexpected insight into mechanisms underlying melanoma development and progression.