title: Aldosterone and angiotensin II synergistically induce mitogenic response in vascular smooth muscle cells.
abstract: Interaction between aldosterone (Aldo) and angiotensin II (Ang II) in the cardiovascular system has been highlighted; however, its detailed signaling mechanism is poorly understood. Here, we examined the cross-talk of growth-promoting signaling between Aldo and Ang II in vascular smooth muscle cells (VSMC). Treatment with a lower dose of Aldo (10(-12) mol/L) and with a lower dose of Ang II (10(-10) mol/L) significantly enhanced DNA synthesis, whereas Aldo or Ang II alone at these doses did not affect VSMC proliferation. This effect of a combination of Aldo and Ang II was markedly inhibited by a selective AT1 receptor blocker, olmesartan, a mineralocorticoid receptor antagonist, spironolactone, an MEK inhibitor, PD98059, or an EGF receptor tyrosine kinase inhibitor, AG1478. Treatment with Aldo together with Ang II, even at noneffective doses, respectively, synergistically increased extracellular signal-regulated kinase (ERK) activation, reaching 2 peaks at 10 to 15 minutes and 2 to 4 hours. The early ERK peak was effectively blocked by olmesartan or an EGF receptor kinase inhibitor, AG1478, but not by spironolactone, whereas the late ERK peak was completely inhibited by not only olmesartan, but also spironolactone. Combined treatment with Aldo and Ang II attenuated mitogen-activated protein kinase phosphatase-1 (MKP-1) expression and increased Ki-ras2A expression. The late ERK peak was not observed in VSMC treated with Ki-ras2A-siRNA. Interestingly, the decrease in MKP-1 expression and the increase in Ki-ras2A expression were restored by PD98059 or AG1478. These results suggest that Aldo exerts a synergistic mitogenic effect with Ang II and support the notion that blockade of both Aldo and Ang II could be more effective to prevent vascular remodeling.
authors.affiliation: Division of Medical Biochemistry and Cardiovascular Biology, Department of Molecular and Cellular Biology, Ehime University School of Medicine, Tohon, Ehime 791-0295, Japan.
authors.forename: Li-Juan
authors.initials: LJ
authors.lastname: Min
authors.forename: Masaki
authors.initials: M
authors.lastname: Mogi
authors.forename: Jian-Mei
authors.initials: JM
authors.lastname: Li
authors.forename: Jun
authors.initials: J
authors.lastname: Iwanami
authors.forename: Masaru
authors.initials: M
authors.lastname: Iwai
authors.forename: Masatsugu
authors.initials: M
authors.lastname: Horiuchi
mesh_terms: D000450:Aldosterone / Q000494:pharmacology*; D000804:Angiotensin II / Q000494:pharmacology*; D000818:Animals; D002118:Calcium / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000032:analysis; D002478:Cells, Cultured; D004247:DNA / Q000096:biosynthesis; D004357:Drug Synergism; D054638:Dual Specificity Phosphatase 1; D004789:Enzyme Activation; D066246:ErbB Receptors / Q000502:physiology; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D011905:Genes, ras; D017874:Immediate-Early Proteins / Q000032:analysis; D020935:MAP Kinase Signaling System; D008934:Mitogens / Q000494:pharmacology*; D009131:Muscle, Smooth, Vascular / Q000187:drug effects* / Q000502:physiology; D010749:Phosphoprotein Phosphatases / Q000032:analysis; D054645:Protein Phosphatase 1; D054562:Protein Tyrosine Phosphatase, Non-Receptor Type 1; D017027:Protein Tyrosine Phosphatases / Q000032:analysis; D051381:Rats; D017207:Rats, Sprague-Dawley; D044140:Receptor, Angiotensin, Type 1 / Q000502:physiology; D015533:Transcriptional Activation
chemical_list: D018797:Cell Cycle Proteins; D017874:Immediate-Early Proteins; D008934:Mitogens; D044140:Receptor, Angiotensin, Type 1; D000804:Angiotensin II; D000450:Aldosterone; D004247:DNA; D066246:ErbB Receptors; D048049:Extracellular Signal-Regulated MAP Kinases; D010749:Phosphoprotein Phosphatases; D054645:Protein Phosphatase 1; D054638:Dual Specificity Phosphatase 1; C517021:Dusp1 protein, rat; D054562:Protein Tyrosine Phosphatase, Non-Receptor Type 1; D017027:Protein Tyrosine Phosphatases; D002118:Calcium