title: Differential baseline expression and angiotensin II-stimulation of leukemia-associated RhoGEF in vascular smooth muscle cells of spontaneously hypertensive rats.
abstract: OBJECTIVE
  Studies to explore angiotensin II (Ang II) and its downstream signaling pathways via Rho guanine nucleotide exchange factors (RhoGEFs) and RhoA signaling are crucial to understanding the mechanisms of smooth muscle contraction leading to hypertension. This study aimed to investigate the Ang II-induced expression of RhoGEFs in vascular smooth muscle cells (VSMCs) of spontaneously hypertensive rats (SHRs) and to identify the possible regulator associated with hypertension.
  
  
  METHODS
  Cultured VSMCs of the aorta from SHRs and Wistar-Kyoto (WKY) rats were treated with or without Ang II or Ang II plus Ang II type 2 receptor antagonists. The expression levels of RhoGEF messenger RNA (mRNA) and protein were determined. To evaluate the changes of aortic ring contractile force in response to Ang II, a nonviral carrier system was adopted to deliver the leukemia-associated RhoGEF (LARG) small interfering RNA via nanoparticles into aortic rings.
  
  
  RESULTS
  The baseline mRNA levels of three RhoGEFs in cultured VSMCs of WKY rats did not increase with age, but they were significantly higher in 12-week-old SHRs than in 5-week-old SHRs. Expression levels of LARG mRNA were higher in SHRs than in age-matched WKY rats. The baseline LAGR protein of 12-week-old SHRs was about four times higher than that of WKY rats of the same age. After Ang II-stimulation, LAGR protein expression was significantly increased in 12-week-old WKY rats but remained unchanged in 12-week-old SHRs. LARG small interfering RNA was successfully delivered into aortic rings using nanoparticles. LARG knockdown resulted in 12-week-old SHRs showing the greatest reduction in aortic ring contraction.
  
  
  CONCLUSIONS
  There were differences in age-related RhoGEF expression at baseline and in response to Ang II-stimulation between SHRs and WKY rats in this study. Nanotechnology can assist in studying the silencing of LARG in tissue culture. The findings of this study indicate that LARG gene expression may be associated with the genesis of hypertension in SHRs.
authors.affiliation: Graduate Institute of Physiology, National Taiwan University College of Medicine, No 7 Chung-Shan South Road, Taipei, Taiwan, Republic of China.
authors.forename: Wei-Chiao
authors.initials: WC
authors.lastname: Chiu
authors.forename: Jyh-Ming
authors.initials: JM
authors.lastname: Juang
authors.forename: Shen-Nan
authors.initials: SN
authors.lastname: Chang
authors.forename: Cho-Kai
authors.initials: CK
authors.lastname: Wu
authors.forename: Chia-Ti
authors.initials: CT
authors.lastname: Tsai
authors.forename: Chuen-den
authors.initials: CD
authors.lastname: Tseng
authors.forename: Yung-Zu
authors.initials: YZ
authors.lastname: Tseng
authors.forename: Ming-Jai
authors.initials: MJ
authors.lastname: Su
authors.forename: Fu-Tien
authors.initials: FT
authors.lastname: Chiang
mesh_terms: D000804:Angiotensin II / Q000378:metabolism* / Q000494:pharmacology*; D000818:Animals; D002478:Cells, Cultured; D005786:Gene Expression Regulation / Q000187:drug effects; D020662:Guanine Nucleotide Exchange Factors / Q000378:metabolism*; D006973:Hypertension / Q000378:metabolism*; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000378:metabolism*; D032389:Myocytes, Smooth Muscle / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D011918:Rats, Inbred SHR; D017208:Rats, Wistar; D064067:Rho Guanine Nucleotide Exchange Factors
chemical_list: C577224:Arhgef12 protein, rat; D020662:Guanine Nucleotide Exchange Factors; D064067:Rho Guanine Nucleotide Exchange Factors; D000804:Angiotensin II