Angiotensin-converting enzyme (ACE) inhibition (ACEi) ameliorates the development of hypertension and the intrarenal ANG II augmentation in ANG II-infused mice. To determine if these effects are associated with changes in the mouse intrarenal renin-angiotensin system, the expression of angiotensinogen (AGT), renin, ACE, angiotensin type 1 receptor (AT(1)R) mRNA (by quanitative RT-PCR) and protein [by Western blot (WB) and/or immunohistochemistry (IHC)] were analyzed. C57BL/6J male mice (9-12 wk old) were distributed as controls (n = 10), ANG II infused (ANG II = 8, 400 ng x kg(-1) x min(-1) for 12 days), ACEi only (ACEi = 10, lisinopril, 100 mg/l), and ANG II infused + ACEi (ANG II + ACEi = 11). When compared with controls (1.00), AGT protein (by WB) was increased by ANG II (1.29 +/- 0.13, P < 0.05), and this was not prevented by ACEi (ACEi + ANG II, 1.31 +/- 0.14, P < 0.05). ACE protein (by WB) was increased by ANG II (1.21 +/- 0.08, P < 0.05), and it was reduced by ACEi alone (0.88 +/- 0.07, P < 0.05) or in combination with ANG II (0.80 +/- 0.07, P < 0.05). AT(1)R protein (by WB) was increased by ANG II (1.27 +/- 0.06, P < 0.05) and ACEi (1.17 +/- 0.06, P < 0.05) but not ANG II + ACEi [1.15 +/- 0.06, not significant (NS)]. Tubular renin protein (semiquantified by IHC) was increased by ANG II (1.49 +/- 0.23, P < 0.05) and ACEi (1.57 +/- 0.15, P < 0.05), but not ANG II + ACEi (1.10 +/- 0.15, NS). No significant changes were observed in AGT, ACE, or AT(1)R mRNA. In summary, reduced responses of intrarenal tubular renin, ACE, and the AT(1)R protein to the stimulatory effects of chronic ANG II infusions, in the presence of ACEi, are associated with the effects of this treatment to ameliorate augmentations in blood pressure and intrarenal ANG II content during ANG II-induced hypertension.

SUMMARY DNA methyltransferase 3a (DNMT3A) catalyzes the formation of 5-methyl-cytosine in mammalian genomic DNA and it is frequently mutated in human hematologic malignancies. Bi-allelic loss of Dnmt3a in mice results in leukemia and lymphoma, including chronic lymphocytic leukemia (CLL). Here we investigate whether mono-allelic loss of Dnmt3a is sufficient to induce disease. We show that by 16 months of age, 65% of Dnmt3a+/− mice develop a CLL-like disease and 15% of mice develop non-malignant myeloproliferation. Genome-wide methylation analysis reveals that reduced Dnmt3a levels induce promoter hypomethylation at similar loci in Dnmt3a+/− and Dnmt3aΔ/Δ CLL, suggesting that promoters are particularly sensitive to Dnmt3a levels. Gene-expression analysis identified 26 hypomethylated and over-expressed genes common to both Dnmt3a+/− and Dnmt3aΔ/Δ CLL as putative oncogenic drivers. Our data provide evidence that Dnmt3a is a haplo-insufficient tumor suppressor in CLL and highlights the importance of deregulated molecular events in disease pathogenesis.

Highlights d Three new Pdgfra/Pdgfrb knockin mice for mosaic mutant analysis were made d Pdgfra and Pdgfrb lineages make distinct contributions to adipocyte differentiation d Differentiation is transiently blocked by constitutive PDGFRa signaling d Mosaic Pdgfra or Pdgfrb knockout enhances white/beige/ brown adipogenesis

DNA methyltransferase 3A (DNMT3A) is an enzyme involved in DNA methylation that is frequently mutated in human hematologic malignancies. We have previously shown that inactivation of Dnmt3a in hematopoietic cells results in chronic lymphocytic leukemia in mice. Here we show that 12% of Dnmt3a-deficient mice develop CD8+ mature peripheral T cell lymphomas (PTCL) and 29% of mice are affected by both diseases. 10% of Dnmt3a+/- mice develop lymphomas, suggesting that Dnmt3a is a haploinsufficient tumor suppressor in PTCL. DNA methylation was deregulated genome-wide with 10-fold more hypo- than hypermethylated promoters and enhancers, demonstrating that hypomethylation is a major event in the development of PTCL. Hypomethylated promoters were enriched for binding sites of transcription factors AML1, NF-κB and OCT1, implying the transcription factors potential involvement in Dnmt3a-associated methylation. Whereas 71 hypomethylated genes showed an increased expression in PTCL, only 3 hypermethylated genes were silenced, suggesting that cancer-specific hypomethylation has broader effects on the transcriptome of cancer cells than hypermethylation. Interestingly, transcriptomes of Dnmt3a+/- and Dnmt3aΔ/Δ lymphomas were largely conserved and significantly overlapped with those of human tumors. Importantly, we observed downregulation of tumor suppressor p53 in Dnmt3a+/- and Dnmt3aΔ/Δ lymphomas as well as in pre-tumor thymocytes from 9 months old but not 6 weeks old Dnmt3a+/- tumor-free mice, suggesting that p53 downregulation is chronologically an intermediate event in tumorigenesis. Decrease in p53 is likely an important event in tumorigenesis because its overexpression inhibited proliferation in mouse PTCL cell lines, suggesting that low levels of p53 are important for tumor maintenance. Altogether, our data link the haploinsufficient tumor suppressor function of Dnmt3a in the prevention of mouse mature CD8+ PTCL indirectly to a bona fide tumor suppressor of T cell malignancies p53.