Project description:Changes in DNA methylation are among the best-documented epigenetic alterations accompanying organismal aging. However, whether and how altered DNA methylation is causally involved in aging have remained elusive. GADD45α (growth arrest and DNA damage protein 45A) and ING1 (inhibitor of growth family member 1) are adapter proteins for site-specific demethylation by TET (ten-eleven translocation) methylcytosine dioxygenases. Here we show that Gadd45a/Ing1 double-knockout mice display segmental progeria and phenocopy impaired energy homeostasis and lipodystrophy characteristic of Cebp (CCAAT/enhancer-binding protein) mutants. Correspondingly, GADD45α occupies C/EBPβ/δ-dependent superenhancers and, cooperatively with ING1, promotes local DNA demethylation via long-range chromatin loops to permit C/EBPβ recruitment. The results indicate that enhancer methylation can affect aging and imply that C/EBP proteins play an unexpected role in this process. Our study suggests a causal nexus between DNA demethylation, metabolism, and organismal aging. This SuperSeries is composed of the SubSeries listed below.
Project description:Changes in DNA methylation are among the best-documented epigenetic alterations accompanying organismal aging. However, whether and how altered DNA methylation is causally involved in aging have remained elusive. GADD45α (growth arrest and DNA damage protein 45A) and ING1 (inhibitor of growth family member 1) are adapter proteins for site-specific demethylation by TET (ten-eleven translocation) methylcytosine dioxygenases. Here we show that Gadd45a/Ing1 double-knockout mice display segmental progeria and phenocopy impaired energy homeostasis and lipodystrophy characteristic of Cebp (CCAAT/enhancer-binding protein) mutants. Correspondingly, GADD45α occupies C/EBPβ/δ-dependent superenhancers and, cooperatively with ING1, promotes local DNA demethylation via long-range chromatin loops to permit C/EBPβ recruitment. The results indicate that enhancer methylation can affect aging and imply that C/EBP proteins play an unexpected role in this process. Our study suggests a causal nexus between DNA demethylation, metabolism, and organismal aging.
Project description:We took a systematic approach to determine the transcriptional programs that are specifically regulated by C/EBP? in mature white adipocytes of mice on chow diet or high fat diet. The hypothesis tested in the present study was that C/EBP?, as a lipogenic transcription factor, has unique direct targets compared to PPAR?. Our inducible adipocyte specific knockout system allows us to test the direct targets of C/EBP? and PPAR? in adipocytes by short-term C/EBP? or PPAR? elimination in mature adipocytes in vivo. Results indicate that although it has been shown that C/EBP? and PPAR? cross-regulate each other, they have distinct direct responsive targets. Moreover, there are very few C/EBP? specific targets in mice on a chow diet, most of the C/EBP? targets in mature adipocytes are genes modulated by HFD feeding. Total RNA obtained from subcutaneous adipose tissue of Adn-C/EBP?-/- mice on doxycycline chow diet for 3 days, doxycycline high fat diet for 3 days or 1 month and Adn-PPAR?-/- mice on doxycycline chow diet for 3 days, compared to control littermates.
Project description:Background: LKB1 is among the most frequently altered tumor suppressors in lung adenocarcinoma. Inactivation of Lkb1 accelerates the growth and progression of oncogenic KRAS-driven lung tumors in mouse models. However, the molecular mechanisms by which LKB1 constrains lung tumorigenesis and whether the aggressive cancer state that stems from Lkb1 deficiency can be reverted remains unknown. Restoration of Lkb1 in established lung tumors promotes the expression of C/EBP target genes as well as features of alveolar type II cell differentiation, which requires the activity of C/EBP transcription factors in the developmental setting. Purpose: To determine the extent to which the disruption of C/EBP transcription factors recapitulates the transcriptional changes induced by the inactivation of Lkb1.Approach: To assess the changes gene expression induced by CRISPR/Cas9-mediated disruption of either C/EBP transcription factors or Lkb1, we induced lung tumors in KrasLSL-G12D/+;R26LSL-tdTomato;H11LSL-Cas9 mice using Lenti-sgNeo1/sgNT/sgNeo2/Cre (sgInert), Lenti-sgLkb1/Cre (sgLkb1), or Lenti-sgCebpa/sgCebpb/sgCebpd/Cre (sgCebpa/b/d). Neoplastic cells were then isolated from lung tumors by FACS for gene expression profiling by RNA-seq. Results: The disruption of C/EBP transcription factors partially recapitulates the gene expression changes induced by Lkb1 inactivation. Among the genes that are jointly dependent upon C/EBP transcription factors and LKB1 is an enrichment of NKX2-1-dependent target genes. Conclusions: C/EBP transcription factors likely operate downstream of LKB1 in an indirect manner, collaborating with another key developmental regulator, NKX2-1, to enforce alveolar type II cell differentiation to constrain tumor growth.
Project description:The molecular mechanisms by which FoxO transcription factors mediate diametrically opposite cellular responses, namely death and survival, remain unknown. Mst1 phosphorylates FoxO1 Ser209/Ser215/Ser218/Thr228/Ser232/Ser243, thereby inducing nuclear translocation of FoxO1 in cardiomyocytes. Mst1 inhibits the FoxO1-mediated transcription of proapoptotic genes but promotes that of prosurvival genes. Mst1 increases FoxO1-C/EBP-β interaction and phosphorylates C/EBP-β at Thr299, thereby promoting transcription of prosurvival genes. Myocardial ischemia/reperfusion (I/R) injury was larger in cardiac-specific FoxO1 knockout (c-FoxO1–/–) mice than in control mice. However, the concurrent presence of C/EBP-β T299E phospho-mimetic mutation reduced infarct size in c-FoxO–/– mice. The C/EBP-β phospho-mimetic mutant exhibited a higher binding to the promoter of prosurvival genes compared to wild-type C/EBP-β. In conclusion, phosphorylation of FoxO1 by Mst1 inhibits the binding of FoxO1 to pro-apoptotic gene promoters but enhances its binding to C/EBP-β, phosphorylation of C/EBP-β, and transcription of prosurvival genes, which stimulate protective mechanisms in the heart.