Angiotensin II-induced ventricular hypertrophy and extracellular signal-regulated kinase activation are suppressed in mice overexpressing brain natriuretic peptide in circulation.
Atrial and brain (B-type) natriuretic peptides (ANP and BNP, respectively) are known to exert various cardioprotective effects. For instance, knocking out the expression of ANP, BNP, or their receptor, guanylyl cyclase-A, induces cardiac hypertrophy and/or fibrosis. The cardiac effects of elevated circulating natriuretic peptides are less well understood, however. We therefore compared angiotensin (Ang) II-induced cardiac hypertrophy and fibrosis in BNP-transgenic (Tg) mice, in which circulating BNP levels were elevated by increased secretion from the liver, and their non-Tg littermates. Left ventricular expression of Ang II type 1a receptor was similar in BNP-Tg and non-Tg mice, and there was no significant difference in the elevation of blood pressure elicited by chronic infusion or acute injection of Ang II. Nevertheless, cardiac hypertrophy and fibrosis were significantly diminished in BNP-Tg mice chronically infused with Ang II. In addition, ventricular activation of extracellular signal-regulated kinase (ERK) induced by acute injection of Ang II was also diminished in BNP-Tg mice, as was activation of ERK kinase (MEK). Conversely, expression of mitogen-activated protein kinase phosphatase (MKP) was significantly increased in the ventricles of BNP-Tg mice. Based on these findings, we conclude that elevated circulating BNP exerts cardioprotective effects via inhibition of a ventricular ERK pathway. The mechanism responsible for this inhibition likely involves 1) increased ventricular MKP expression and 2) inhibition of transduction mediators situated upstream of ERK.
Takahashi
Nobuki
N
Department of Medicine and Clinical Science. Kyoto University Graduate School of Medicine, Kyoto, Japan.
Saito
Yoshihiko
Y
Kuwahara
Koichiro
K
Harada
Masaki
M
Kishimoto
Ichiro
I
Ogawa
Yoshihiro
Y
Kawakami
Rika
R
Nakagawa
Yasuaki
Y
Nakanishi
Michio
M
Nakao
Kazuwa
K
D000804:Angiotensin II / Q000494:pharmacology; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D005355:Fibrosis; D015870:Gene Expression; D017379:Hypertrophy, Left Ventricular / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D048369:MAP Kinase Kinase 1; D048370:MAP Kinase Kinase 2; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000502:physiology*; D051379:Mice; D008822:Mice, Transgenic; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009206:Myocardium / Q000378:metabolism / Q000473:pathology; D020097:Natriuretic Peptide, Brain / Q000097:blood* / Q000235:genetics*; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D016760:Proto-Oncogene Proteins c-fos / Q000235:genetics; D012333:RNA, Messenger / Q000032:analysis; D044140:Receptor, Angiotensin, Type 1 / Q000235:genetics / Q000378:metabolism; D014662:Vasoconstrictor Agents / Q000494:pharmacology
D016760:Proto-Oncogene Proteins c-fos; D012333:RNA, Messenger; D044140:Receptor, Angiotensin, Type 1; D014662:Vasoconstrictor Agents; D000804:Angiotensin II; D020097:Natriuretic Peptide, Brain; D011505:Protein-Tyrosine Kinases; D020928:Mitogen-Activated Protein Kinases; D048369:MAP Kinase Kinase 1; D048370:MAP Kinase Kinase 2; C482127:Map2k1 protein, mouse; D020929:Mitogen-Activated Protein Kinase Kinases