Project description:Cardiomyocyte-specific double knockout (DKO) mice lacking the catalytic domains of Dnmt3a (exon 18) and Dnmt3b (exon 19) were obtained by mating Dnmt3aflox and Dnmt3bflox mice [PMID 15757890] with mice expressing a cre recombinase under control of the cardiac atrial myosin light chain promoter (Myl7) [11689889]. Mice with the genotype Dnmt3aflox/flox, Dnmt3bflox/flox without expressing cre recombinase were used as control mice (CTL). Transcriptome analyses identified upregulation of 44 and downregulation of 9 genes in DKO as compared with control sham mice. TAC mice showed similar changes with substantial overlap of regulated genes compared to sham. Cardiac tissue from sham CTL (n=4) and DKO mice (n=4) as well as TAC-operated CTL (n=6) and DKO mice (n=6) was analysed.
Project description:Cardiomyocyte-specific double knockout (DKO) mice lacking the catalytic domains of Dnmt3a (exon 18) and Dnmt3b (exon 19) were obtained by mating Dnmt3aflox and Dnmt3bflox mice [PMID 15757890] with mice expressing a cre recombinase under control of the cardiac atrial myosin light chain promoter (Myl7) [11689889]. Mice with the genotype Dnmt3aflox/flox, Dnmt3bflox/flox without expressing cre recombinase were used as control mice (CTL). Transcriptome analyses identified upregulation of 44 and downregulation of 9 genes in DKO as compared with control sham mice. TAC mice showed similar changes with substantial overlap of regulated genes compared to sham.
Project description:Cytosine methylation is an epigenetic mark that dictates cell fate and response to stimuli. The timing and establishment of methylation logic during kidney development remains unknown. DNA methyltransferase 3a and 3b are the enzymes capable of establishing de novo methylation. We generated mice with genetic deletion of Dnmt3a and Dnmt3b in nephron progenitor cells (Six2Cre Dnmt3a/3b) and kidney tubule cells (KspCre Dnmt3a/3b). We characterized KspCre Dnmt3a/3b mice at baseline and after injury. Unbiased omics profiling, such as whole genome bisulfite sequencing, reduced representation bisulfite sequencing and RNA sequencing were performed on whole-kidney samples and isolated renal tubule cells. KspCre Dnmt3a/3b mice showed no obvious morphologic and functional alterations at baseline. Knockout animals exhibited increased resistance to cisplatin-induced kidney injury, but not to folic acid–induced fibrosis. Whole-genome bisulfite sequencing indicated that Dnmt3a and Dnmt3b play an important role in methylation of gene regulatory regions that act as fetal-specific enhancers in the developing kidney but are decommissioned in the mature kidney. Loss of Dnmt3a and Dnmt3b resulted in failure to silence developmental genes. We also found that fetal-enhancer regions methylated by Dnmt3a and Dnmt3b were enriched for kidney disease genetic risk loci. Methylation patterns of kidneys from patients with CKD showed defects similar to those in mice with Dnmt3a and Dnmt3b deletion. Our results indicate a potential locus-specific convergence of genetic, epigenetic, and developmental elements in kidney disease development.
Project description:We created mice, which are deficient for Myc specifically in cardiac myocytes by crossing crossed Myc-floxed mice (Mycfl/fl) and MLC-2VCre/+ mice. Serial analysis of earlier stages of gestation revealed that Myc-deficient mice died prematurely at E13.5-14.5. Morphological analyses of E13.5 Myc-null embryos showed normal ventricular size and structure; however, decreased cardiac myocyte proliferation and increased apoptosis was observed. BrdU incorporation rates were also decreased significantly in Myc-null myocardium. Myc-null mice displayed a 3.67-fold increase in apoptotic cardiomyocytes by TUNEL assay. We examined global gene expression using oligonucleotide microarrays. Numerous genes involved in mitochondrial death pathways were dysregulated including Bnip3L and Birc2. Hearts were taken from wide type and Myc-null Mouse embryos at E13.5 under the dissecting scope. Cardiac myocyte RNA was isolated using TRIZOL®Reagent Total RNA (100 ng) was hybridized to the Sentrix® MouseRef-8 Expression BeadChip that contains probes for ~24,000 transcripts. GeneChips were scanned using the Hewlett-Packard GeneArray Scanner G2500A. The data were analyzed with Illumina Inc. BeadStudio version 1.5.0.34 and normalized by rank invariant method.
Project description:The de novo DNA methyltransferase Dnmt3a is mutated in human acute myeloid leukemia, and suppresses tumorigenesis in murine models of leukemia and lung cancer. Conversely, deregulation of the other de novo DNA methyltransferase, Dnmt3b, predominantly promotes tumorigenesis. However, the molecular mechanisms underlying the roles of Dnmt3a and Dnmt3b in cancer remain poorly understood. Using conditional knockout mice, here we show that Dnmt3a -- but not Dnmt3b -- strongly protects epidermal stem cells from carcinogen-induced tumor initiation, without affecting the progression of benign lesions to aggressive carcinomas. Only upon combined deletion of Dnmt3a and Dnmt3b, squamous cell carcinomas acquired a more aggressive fate and even became metastatic, indicating that Dnmt3b is tumor-suppressive, rather than pro-tumorigenic, in epidermal neoplasia. Mechanistically, Dnmt3a promotes the expression of epidermal differentiation genes by interacting with their enhancers, and inhibits the expression of lipid metabolism and cell proliferation genes by directly methylating their promoters. Altogether, we demonstrate that Dnmt3a, but not Dnmt3b, is critical for suppressing epidermal tumor initiation, while both enzymes prevent tumor progression.
Project description:The de novo DNA methyltransferase Dnmt3a is mutated in human acute myeloid leukemia, and suppresses tumorigenesis in murine models of leukemia and lung cancer. Conversely, deregulation of the other de novo DNA methyltransferase, Dnmt3b, predominantly promotes tumorigenesis. However, the molecular mechanisms underlying the roles of Dnmt3a and Dnmt3b in cancer remain poorly understood. Using conditional knockout mice, here we show that Dnmt3a -- but not Dnmt3b -- strongly protects epidermal stem cells from carcinogen-induced tumor initiation, without affecting the progression of benign lesions to aggressive carcinomas. Only upon combined deletion of Dnmt3a and Dnmt3b, squamous cell carcinomas acquired a more aggressive fate and even became metastatic, indicating that Dnmt3b is tumor-suppressive, rather than pro-tumorigenic, in epidermal neoplasia. Mechanistically, Dnmt3a promotes the expression of epidermal differentiation genes by interacting with their enhancers, and inhibits the expression of lipid metabolism and cell proliferation genes by directly methylating their promoters. Altogether, we demonstrate that Dnmt3a, but not Dnmt3b, is critical for suppressing epidermal tumor initiation, while both enzymes prevent tumor progression.