Angiotensin II regulates the LARG/RhoA/MYPT1 axis in rat vascular smooth muscle in vitro

Acta Pharmacol Sin. 2012 Dec;33(12):1502-10. doi: 10.1038/aps.2012.117. Epub 2012 Nov 5.


Aim: To identify a key protein that binds monomeric G protein RhoA and activates the RhoA/Rho kinase/MYPT1 axis in vascular smooth muscle cells (VSMCs) upon angiotensin II (Ang II) stimulation.

Methods: Primary cultured VSMCs from Sprague-Dawley rats were transfected with siRNAs against leukemia-associated RhoGEF (LARG), and then treated with Ang II, losartan, PD123319, or Val(5)-Ang II. The target mRNA and protein levels were determined using qPCR and Western blot analysis, respectively. Rat aortic rings were isolated, and the isometric contraction was measured with a force transducer and recorder.

Results: Stimulation with Ang II (0.1 μmol/L) for 0.5 h significantly increased the level of LARG mRNA in VSMCs. At 3, 6, and 9 h after the treatment with Ang II (0.1 μmol/L) plus AT(2) antagonist PD123319 (1 μmol/L) or with AT(1) agonist Val(5)-Ang II (1 μmol/L), the LARG protein, RhoA activity, and phosphorylation level of myosin phosphatase target subunit 1 (MYPT1) in VSMCs were significantly increased. Knockdown of LARG with siRNA reduced these effects caused by AT(1) receptor activation. In rat aortic rings pretreated with LARG siRNA, Ang II-induced contraction was diminished.

Conclusion: Ang II upregulates LARG gene expression and activates the LARG/RhoA/MYPT1 axis via AT(1), thereby maintaining vascular tone.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Angiotensin II / metabolism
  • Angiotensin II / pharmacology*
  • Animals
  • Aorta, Thoracic / drug effects
  • Aorta, Thoracic / physiopathology
  • Blotting, Western
  • Cells, Cultured
  • Gene Expression Regulation / drug effects*
  • Guanine Nucleotide Exchange Factors / genetics*
  • Isometric Contraction / drug effects
  • Male
  • Muscle, Smooth, Vascular / drug effects*
  • Muscle, Smooth, Vascular / enzymology
  • Muscle, Smooth, Vascular / metabolism
  • Primary Cell Culture
  • Protein Phosphatase 1 / metabolism*
  • RNA, Small Interfering / genetics
  • Rats
  • Rats, Sprague-Dawley
  • Real-Time Polymerase Chain Reaction
  • Rho Guanine Nucleotide Exchange Factors
  • Up-Regulation
  • rhoA GTP-Binding Protein / metabolism*


  • Arhgef12 protein, rat
  • Guanine Nucleotide Exchange Factors
  • RNA, Small Interfering
  • Rho Guanine Nucleotide Exchange Factors
  • Angiotensin II
  • Ppp1r12a protein, rat
  • Protein Phosphatase 1
  • rhoA GTP-Binding Protein