Author + information
- Wang Tingjun,
- Guili Lian,
- Changsheng Xu,
- Xu Lin,
- Wanru Chen and
- Liangdi Xie
To investigate long-term influence of early treatment of spontaneously hypertensive rats (SHR) with losartan (Los) on blood pressure, left ventricular hypertrophy and expression of angiotensin type 1 receptor-associated protein (ATRAP) in myocardium, and to explore the role of DNA methylation in the long-term effect of Los.
1. pregnant Wistar kyoto rats(WKY)and SHR were randomly divided into five groups: untreated WKY group (WKYUn), untreated SHR group (SHRUn), prenatal Los-treated SHR (SHRPre), postnatal Los-treated SHR (SHRPost) and sequential Los-treated SHR (SHRSeq). Systolic blood pressure, LVM/BW, ATRAP and DNA methyltransferase (DNMT)1, DNMT3a and DNMT3b expression in myocardium were measured in adult male offspring rats. The methylation level in ATRAP gene promoter was assessed by bisulfite sequencing polymerase chain reaction. Chromatin immunoprecipitation assay (Chip assay) was used to analyze the binding of DNMTs to ATRAP gene. 2. H9c2 cells were treated with Los or DNA methyltransferase inhibitor 5-aza-2'-deoxycytidine (5-Aza) prior to stimulation with Ang II, the rate of protein synthesis, ATRAP expression and DNA methylation were observed. 3H leucine incorporation was used to evaluate the protein synthesis.
SBP and LVM/BW were significantly lower [SBP: (189±20), (174±16), (173±17) vs. (212±22) mmHg; LVM/BW: (2.72±0.24), (2.45±0.24), (2.43±0.28) vs. (3.12±0.28) mg/g, P<0.05], the expression of ATRAP in myocardium was significantly higher in SHRPre, SHRPost and SHRSeq than SHRUn group. The methylation levels of ATRAP gene promoter and the bindings of DNMT1 and DNMT3a to ATRAP gene in myocardium in SHRUn group were higher than WKYUn group. SHRPre, SHRPost and SHR Seq group demonstrated lower methylation levels of ATRAP gene promoter and bindings of DNMT1 and DNMT3a to ATRAP gene compared with SHRUn. The rate of protein synthesis was significantly increased, and ATRAP expression was significantly decreased in H9c2 cells in response to AngII, concomitant with the increase in methylation levels in ATRAP gene promoter, DNMT1 and DNMT3a expression and bindings of DNMT1, DNMT3a to ATRAP gene. These effects of AngII on H9c2 cells were reversed by Los and 5-Aza to different extent.
Early treatment of SHR with Los could persistently postpone the increase in BP, inhibit LVH, reduce cardiac level of ATRAP expression, DNA methylation is likely to be the mechanism underlying the long-term effect of Los.