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:The RNA-sequence analysis of cardiomyocyte-specific deletion of STAT3 mice hearts showed that comparing with WT mice hearts, the STAT3cKO mice hearts showed reduced cardiac function by affecting some key pathways.
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.
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:Genome wide gene expression analysis of mRNA siolated from whole heart tissue from wild type and cardiomyocyte selective MR null mice. The role of mineralocorticoid receptors (MR) in specific cell types of the myocardium in cardiac remodeling remains unknown. We investigated MR in cardiomyocytes in DOC/salt-induced cardiac pathology. Cardiomyocyte MR-null mice (CM-MRKO) and control mice (WT) were given DOC/salt and cardiac responses were examined at 8 days and 8 weeks. Cardiac function in untreated mice wild type and CM-MRKO mice was determined by Langendorf and showed no differences. At 8 days CM-MRKO showed equivalent monocyte/macrophage recruitment to wild type mice in response to DOC/salt treatment. Profibrotic markers were significantly reduced in CM-MRKO hearts at base line and in response to DOC/salt. In contrast, at 8 weeks CM-MRKO mice showed no DOC/salt-induced increase in inflammatory cell infiltrate, fibrosis or systolic blood pressure (SBP). Similarly, DOC/salt-mediated increases in proinflammatory and profibrotic gene expression were not detected in CM-MRKO mice. Although mRNA levels for fibronectin and collagen III were similar for each genotype, this was not translated into protein expression. Interestingly, untreated CM-MRKO mice showed increased mRNA and protein for decorin and a further increase with DOC/salt. Together, these data suggest a direct role for cardiomyocyte MR in DOC/salt-induced tissue remodelling and SBP regulation. Moreover, a specific profibrotic pathway is dysregulated in CM-MRKO mice, suggesting a potential mechanism for the cardioprotective effects of selective MR deletion in cardiomyocytes. Pool mRNA (equal amounts) from whole heart from 8 animals per group.
Project description:DNA methylation is generally known to inactivate gene expression. The DNA methyltransferases (DNMTs), DNMT3A and DNMT3B, catalyze somatic cell lineage-specific DNA methylation, while DNMT3A and DNMT3L catalyze germ cell lineage-specific DNA methylation. How such lineage- and gene-specific DNA methylation patterns are created remains to be elucidated. To better understand the regulatory mechanisms underlying DNA methylation, we generated transgenic mice that constitutively expressed DNMT3A and DNMT3L, and analyzed DNA methylation, gene expression, and their subsequent impact on ontogeny. All transgenic mice were born normally but died within 20 weeks accompanied with cardiac hypertrophy. Several genes were repressed in the hearts of transgenic mice compared with those in wild-type mice. CpG islands of these downregulated genes were highly methylated in the transgenic mice. This abnormal methylation occurred in the perinatal stage. Conversely, mono-allelic DNA methylation at imprinted loci was faithfully maintained in all transgenic mice, except H19. Thus, the loci preferred by DNMT3A and DNMT3L differ between somatic and germ cell lineages.
Project description:Growth and expansion of ventricular chambers is essential during cardiogenesis and is achieved by proliferation of cardiac progenitors that are not fully differentiated. Disruption of this process can lead to prenatal lethality. In contrast, adult cardiomyocytes achieve growth through hypertrophy rather than hyperplasia. Although epicardial-derived signals may contribute to the proliferative process in myocytes, the factors and cell types responsible for development of the ventricular myocardial thickness are unclear. Moreover, the function of embryonic cardiac fibroblasts, derived from epicardium, and their secreted factors are largely unknown. Using a novel co-culture system, we found that embryonic cardiac fibroblasts induced proliferation of cardiomyocytes, in contrast to adult cardiac fibroblasts that promoted myocyte hypertrophy. We identified fibronectin, collagen and heparin-binding EGF-like growth factor as embryonic cardiac fibroblast-specific signals that collaboratively promoted cardiomyocyte proliferation in a paracrine fashion. b1 integrin was required for this proliferative response, and ventricular cardiomyocyte-specific deletion of b1 integrin in mice resulted in reduced myocardial proliferation and impaired ventricular compaction. These findings reveal a previously unrecognized paracrine function of embryonic cardiac fibroblasts in regulating cardiomyocyte proliferation. To investigate the mechanisms responsible for the abnormalities in b1 integrin mutant mice, we performed mRNA expression microarray analyses of E12.5 wild-type and mutant hearts, well before any obvious dysfunction. RNA was isolated from wild-type and mutant hearts, and arrays were performed using Affymetrix mouse Gene 1.0 ST arrays. Analysis was performed on three biological replicates of WT and KO mouse hearts.