Contribution of extracellular signal-regulated kinase to angiotensin II-induced transforming growth factor-beta1 expression in vascular smooth muscle cells.
We have previously demonstrated that angiotensin II (Ang II) contributes to the increase in aortic transforming growth factor-beta(1) (TGF-beta(1)) mRNA levels in hypertensive rats. However, the molecular mechanism whereby Ang II promotes TGF-beta(1) expression in vascular smooth muscle cells (VSMCs) is poorly understood. In this study, we examined the role of extracellular signal-regulated kinase (ERK) in Ang II-mediated TGF-beta(1) expression in VSMCs and the role of Ang II in aortic ERK activity of stroke-prone spontaneously hypertensive rats. Treatment of quiescent VSMCs with 100 nmol/L Ang II induced rapid phosphorylation and activation of ERK1 and ERK2 with a peak at 5 minutes followed by an increase in activator protein-1 (AP-1) DNA binding activity, as shown by gel mobility shift assay. An increase in TGF-beta(1) mRNA was shown by Northern blot analysis. Treatment of VSMCs with PD98059, a specific inhibitor of the ERK pathway, attenuated both the activation of AP-1 and the increase in TGF-beta(1) mRNA induced by Ang II. Inhibition of Ang II-induced AP-1 activation with c-fos antisense oligodeoxynucleotide led to a significant reduction of TGF-beta(1) mRNA in VSMCs. Furthermore, in vivo treatment of stroke-prone spontaneously hypertensive rats with losartan, an Ang II type 1 receptor antagonist, decreased aortic ERK activity. Thus, we show that ERK, through AP-1 activation, is involved in Ang II-induced TGF-beta(1) mRNA expression in VSMCs and suggest that ERK may participate in vascular remodeling of hypertension. However, it remains to be determined whether the increase in TGF-beta(1) mRNA leads to the increase in its active protein.
Department of Pharmacology, Osaka City University Medical School, Osaka 545-8585, Japan.
A
A
Hamaguchi
S
S
Kim
Y
Y
Izumi
Y
Y
Zhan
S
S
Yamanaka
H
H
Iwao
D000804:Angiotensin II / Q000494:pharmacology*; D057911:Angiotensin Receptor Antagonists; D000818:Animals; D001011:Aorta / Q000201:enzymology; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000502:physiology*; D004268:DNA-Binding Proteins / Q000378:metabolism; D004789:Enzyme Activation / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005419:Flavonoids / Q000494:pharmacology; D006973:Hypertension / Q000201:enzymology / Q000235:genetics; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D016376:Oligonucleotides, Antisense / Q000494:pharmacology; D010766:Phosphorylation; D016760:Proto-Oncogene Proteins c-fos / Q000235:genetics; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D017207:Rats, Sprague-Dawley; D044140:Receptor, Angiotensin, Type 1; D044139:Receptor, Angiotensin, Type 2; D018808:Transcription Factor AP-1 / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000378:metabolism*
D057911:Angiotensin Receptor Antagonists; D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; D005419:Flavonoids; D016376:Oligonucleotides, Antisense; D016760:Proto-Oncogene Proteins c-fos; D044140:Receptor, Angiotensin, Type 1; D044139:Receptor, Angiotensin, Type 2; D018808:Transcription Factor AP-1; D016212:Transforming Growth Factor beta; D000804:Angiotensin II; D017871:Calcium-Calmodulin-Dependent Protein Kinases; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one