Aberrant DNA methylation of hypothalamic angiotensin receptor in prenatal programmed hypertension
Fumiko Kawakami-Mori, Mitsuhiro Nishimoto, Latapati Reheman, Wakako Kawarazaki, Nobuhiro Ayuzawa, Kohei Ueda, Daigoro Hirohama, Daisuke Kohno, Shigeyoshi Oba, Tatsuo Shimosawa, Takeshi Marumo, Toshiro Fujita
Fumiko Kawakami-Mori, Mitsuhiro Nishimoto, Latapati Reheman, Wakako Kawarazaki, Nobuhiro Ayuzawa, Kohei Ueda, Daigoro Hirohama, Daisuke Kohno, Shigeyoshi Oba, Tatsuo Shimosawa, Takeshi Marumo, Toshiro Fujita
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Aberrant DNA methylation of hypothalamic angiotensin receptor in prenatal programmed hypertension

Abstract

Maternal malnutrition, which causes prenatal exposure to excessive glucocorticoid, induces adverse metabolic programming, leading to hypertension in offspring. In offspring of pregnant rats receiving a low-protein diet or dexamethasone, a synthetic glucocorticoid, mRNA expression of angiotensin receptor type 1a (Agtr1a) in the paraventricular nucleus (PVN) of the hypothalamus was upregulated, concurrent with reduced expression of DNA methyltransferase 3a (Dnmt3a), reduced binding of DNMT3a to the Agtr1a gene, and DNA demethylation. Salt loading increased BP in both types of offspring, suggesting that elevated hypothalamic Agtr1a expression is epigenetically modulated by excessive glucocorticoid and leads to adult-onset salt-sensitive hypertension. Consistent with this, dexamethasone treatment of PVN cells upregulated Agtr1a, while downregulating Dnmt3a, and decreased DNMT3a binding and DNA demethylation at the Agtr1a locus. In addition, Dnmt3a knockdown upregulated Agtr1a independently of dexamethasone. Hypothalamic neuron–specific Dnmt3a-deficient mice exhibited upregulation of Agtr1a in the PVN and salt-induced BP elevation without dexamethasone treatment. By contrast, dexamethasone-treated Agtr1a-deficient mice failed to show salt-induced BP elevation, despite reduced expression of Dnmt3a. Thus, epigenetic modulation of hypothalamic angiotensin signaling contributes to salt-sensitive hypertension induced by prenatal glucocorticoid excess in offspring of mothers that are malnourished during pregnancy.

Authors

Fumiko Kawakami-Mori, Mitsuhiro Nishimoto, Latapati Reheman, Wakako Kawarazaki, Nobuhiro Ayuzawa, Kohei Ueda, Daigoro Hirohama, Daisuke Kohno, Shigeyoshi Oba, Tatsuo Shimosawa, Takeshi Marumo, Toshiro Fujita

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Figure 5

Salt-sensitive hypertension in offspring of hypothalamic neuron–specific Dnmt3a-KO mice without dexamethasone (Dex) treatment during pregnancy.

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Salt-sensitive hypertension in offspring of hypothalamic neuron–specific...
(A) BW at weeks 1 and 12 in the flox mice (n = 6 and 10, respectively) and hypothalamic neuron-specific Dnmt3a-KO mice (n = 8 and 8, respectively). Filled circle, Dex-untreated flox mice; open circle, Dex-untreated Dnmt3a-KO mice. (B) Real-time PCR of Agtr1a (n = 9), Agtr1b (n = 8), and Agtr2 (n = 8) mRNA in PVN of flox and Dnmt3a-KO mice. Filled circle, Dex-untreated flox mice; open circle, Dex-untreated Dnmt3a-KO mice. (C) Mean BP by radiotelemetry before and after 1 week of HS in Dex-untreated flox mice (n = 4, left) and Dex-untreated Dnmt3a-KO mice (n = 4, right). Filled circle, Dex-untreated flox mice; open circles, Dex-untreated Dnmt3a-KO mice. In A and B, *P < 0.05 versus Dex-untreated flox mice (t test); in C, *P < 0.05 versus HS-treated flox mice or NS-treated Dnmt3a-KO mice (2-way repeated ANOVA, Bonferroni post hoc text). (D) In situ hybridization of Agtr1a mRNA in the PVN of Sim1-Cre Dnmt3a-KO (right) and flox mice (left) (upper panels, low power; lower panels, high power). Hybridization using an antisense probe indicates expression of Agtr1a mRNA (purple, lower panel). Hybridization using the sense probe yielded no detectable signals in the PVN (data not shown). Scale bar: 100 μm. (E) Upper panels show staining for Iba1, a marker of glia cells (brown), and lower panels show GFAP, a marker of astrocytes (brown). Agtr1a (blue) colocalized with neither Iba1 nor GFAP, suggesting that it is expressed mainly in neuronal cells. The expression pattern was not affected by Sim1-Cre Dnmt3a–KO. Scale bars: 50 μm.