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Aliskiren ameliorates pressure overload-induced heart hypertrophy and fibrosis in mice.

Weng LQ, Zhang WB, Ye Y, Yin PP, Yuan J, Wang XX, Kang L, Jiang SS, You JY, Wu J, Gong H, Ge JB, Zou YZ - Acta Pharmacol. Sin. (2014)

Bottom Line: The levels of signaling proteins were measured using Western blotting, while the expression of the relevant genes was analyzed using real-time QRT-PCR.These pathological alterations in TAC-mice were significantly ameliorated or blocked by ALK administration.In mechanically stretched cardiomyocytes, CGP53353 (a PKCβI inhibitor) prevented ERK phosphorylation and autophagic responses, while U0126 (an ERK inhibitor) blocked autophagic responses.

View Article: PubMed Central - PubMed

Affiliation: Shanghai Institute of Cardiovascular Diseases, Zhongshan Hospital and Institute of Biomedical Science, Fudan University, Shanghai 200032, China.

ABSTRACT

Aim: Aliskiren (ALK) is a renin inhibitor that has been used in the treatment of hypertension. The aim of this study was to determine whether ALK could ameliorate pressure overload-induced heart hypertrophy and fibrosis, and to elucidate the mechanisms of action.

Methods: Transverse aortic constriction (TAC) was performed in mice to induce heart pressure overload. ALK (150 mg·kg(-1)·d(-1), po), the autophagy inhibitor 3-methyladenine (10 mg·kg(-1) per week, ip) or the PKCβI inhibitor LY333531 (1 mg·kg(-1)·d-(1), po) was administered to the mice for 4 weeks. Heart hypertrophy, fibrosis and function were evaluated based on echocardiography, histological and biochemical measurements. Mechanically stretched cardiomyocytes of rats were used for in vitro experiments. The levels of signaling proteins were measured using Western blotting, while the expression of the relevant genes was analyzed using real-time QRT-PCR.

Results: TAC induced marked heart hypertrophy and fibrosis, accompanied by high levels of Ang II in plasma and heart, and by PKCβI/α and ERK1/2 phosphorylation in heart. Meanwhile, TAC induced autophagic responses in heart, i.e. increases in autophagic structures, expression of Atg5 and Atg16 L1 mRNAs and LC3-II and Beclin-1 proteins. These pathological alterations in TAC-mice were significantly ameliorated or blocked by ALK administration. In TAC-mice, 3-methyladenine administration also ameliorated heart hypertrophy, fibrosis and dysfunction, while LY333531 administration inhibited ERK phosphorylation and autophagy in heart. In mechanically stretched cardiomyocytes, CGP53353 (a PKCβI inhibitor) prevented ERK phosphorylation and autophagic responses, while U0126 (an ERK inhibitor) blocked autophagic responses.

Conclusion: ALK ameliorates heart hypertrophy, fibrosis and dysfunction in the mouse model in setting of chronic pressure overload, via suppressing Ang II-PKCβI-ERK1/2-regulated autophagy.

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Effect of ALK on TAC-induced change in the levels of Ang I/Ang II, PKC isoforms, and MAPK. (A) Angiotensin concentrations in plasma and heart of experimental mice. Ang I, Angiotensin I; Ang II, Angiotensin II. (B) Representative gel blots and quantitative analysis of phosphorylated PKCα, βI, βII, and γ. (C) Representative gel blots of ERK, pERK, p38, pP38, JNK, and pJNK, and quantitative analysis of pERK, pP38, and pJNK. GAPDH served as the internal control. n=6. Mean±SEM. bP<0.05 vs Sham. eP<0.05 vs TAC. hP<0.05 vs ALK.
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fig4: Effect of ALK on TAC-induced change in the levels of Ang I/Ang II, PKC isoforms, and MAPK. (A) Angiotensin concentrations in plasma and heart of experimental mice. Ang I, Angiotensin I; Ang II, Angiotensin II. (B) Representative gel blots and quantitative analysis of phosphorylated PKCα, βI, βII, and γ. (C) Representative gel blots of ERK, pERK, p38, pP38, JNK, and pJNK, and quantitative analysis of pERK, pP38, and pJNK. GAPDH served as the internal control. n=6. Mean±SEM. bP<0.05 vs Sham. eP<0.05 vs TAC. hP<0.05 vs ALK.

Mentions: The plasma and cardiac levels of Ang I and Ang II were significantly elevated in the TAC control group, compared with those in the Sham group. ALK effectively downregulated the TAC-induced upregulation of both Ang I and Ang II (Figure 4A). To investigate which PKC isoforms contributed to TAC-induced cardiac abnormalities and whether these activated PKC isoforms may be inhibited by ALK, the expression levels of pPKCα, pPKCβI, pPKCβII, and pPKCγ were examined. The isoforms pPKCβII and pPKCγ did not increase, but pPKCα and pPKCβI both increased in the TAC control group. Of note, the elevated cardiac isoforms pPKCα and pPKCβI were apparently attenuated in response to chronic renin inhibition with ALK (Figure 4B). To explore the molecular mechanism of this process further, the mitogen-activated protein kinases (MAPK) were investigated. Pressure overload induced an evident rise in the phosphorylation levels of ERK1/2, p38 MAPK, and JNK1/2; however, ALK treatment markedly blocked the activation of ERK1/2, whereas p38 MAPK and JNK1/2 were not significantly affected (Figure 4C).


Aliskiren ameliorates pressure overload-induced heart hypertrophy and fibrosis in mice.

Weng LQ, Zhang WB, Ye Y, Yin PP, Yuan J, Wang XX, Kang L, Jiang SS, You JY, Wu J, Gong H, Ge JB, Zou YZ - Acta Pharmacol. Sin. (2014)

Effect of ALK on TAC-induced change in the levels of Ang I/Ang II, PKC isoforms, and MAPK. (A) Angiotensin concentrations in plasma and heart of experimental mice. Ang I, Angiotensin I; Ang II, Angiotensin II. (B) Representative gel blots and quantitative analysis of phosphorylated PKCα, βI, βII, and γ. (C) Representative gel blots of ERK, pERK, p38, pP38, JNK, and pJNK, and quantitative analysis of pERK, pP38, and pJNK. GAPDH served as the internal control. n=6. Mean±SEM. bP<0.05 vs Sham. eP<0.05 vs TAC. hP<0.05 vs ALK.
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Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4125714&req=5

fig4: Effect of ALK on TAC-induced change in the levels of Ang I/Ang II, PKC isoforms, and MAPK. (A) Angiotensin concentrations in plasma and heart of experimental mice. Ang I, Angiotensin I; Ang II, Angiotensin II. (B) Representative gel blots and quantitative analysis of phosphorylated PKCα, βI, βII, and γ. (C) Representative gel blots of ERK, pERK, p38, pP38, JNK, and pJNK, and quantitative analysis of pERK, pP38, and pJNK. GAPDH served as the internal control. n=6. Mean±SEM. bP<0.05 vs Sham. eP<0.05 vs TAC. hP<0.05 vs ALK.
Mentions: The plasma and cardiac levels of Ang I and Ang II were significantly elevated in the TAC control group, compared with those in the Sham group. ALK effectively downregulated the TAC-induced upregulation of both Ang I and Ang II (Figure 4A). To investigate which PKC isoforms contributed to TAC-induced cardiac abnormalities and whether these activated PKC isoforms may be inhibited by ALK, the expression levels of pPKCα, pPKCβI, pPKCβII, and pPKCγ were examined. The isoforms pPKCβII and pPKCγ did not increase, but pPKCα and pPKCβI both increased in the TAC control group. Of note, the elevated cardiac isoforms pPKCα and pPKCβI were apparently attenuated in response to chronic renin inhibition with ALK (Figure 4B). To explore the molecular mechanism of this process further, the mitogen-activated protein kinases (MAPK) were investigated. Pressure overload induced an evident rise in the phosphorylation levels of ERK1/2, p38 MAPK, and JNK1/2; however, ALK treatment markedly blocked the activation of ERK1/2, whereas p38 MAPK and JNK1/2 were not significantly affected (Figure 4C).

Bottom Line: The levels of signaling proteins were measured using Western blotting, while the expression of the relevant genes was analyzed using real-time QRT-PCR.These pathological alterations in TAC-mice were significantly ameliorated or blocked by ALK administration.In mechanically stretched cardiomyocytes, CGP53353 (a PKCβI inhibitor) prevented ERK phosphorylation and autophagic responses, while U0126 (an ERK inhibitor) blocked autophagic responses.

View Article: PubMed Central - PubMed

Affiliation: Shanghai Institute of Cardiovascular Diseases, Zhongshan Hospital and Institute of Biomedical Science, Fudan University, Shanghai 200032, China.

ABSTRACT

Aim: Aliskiren (ALK) is a renin inhibitor that has been used in the treatment of hypertension. The aim of this study was to determine whether ALK could ameliorate pressure overload-induced heart hypertrophy and fibrosis, and to elucidate the mechanisms of action.

Methods: Transverse aortic constriction (TAC) was performed in mice to induce heart pressure overload. ALK (150 mg·kg(-1)·d(-1), po), the autophagy inhibitor 3-methyladenine (10 mg·kg(-1) per week, ip) or the PKCβI inhibitor LY333531 (1 mg·kg(-1)·d-(1), po) was administered to the mice for 4 weeks. Heart hypertrophy, fibrosis and function were evaluated based on echocardiography, histological and biochemical measurements. Mechanically stretched cardiomyocytes of rats were used for in vitro experiments. The levels of signaling proteins were measured using Western blotting, while the expression of the relevant genes was analyzed using real-time QRT-PCR.

Results: TAC induced marked heart hypertrophy and fibrosis, accompanied by high levels of Ang II in plasma and heart, and by PKCβI/α and ERK1/2 phosphorylation in heart. Meanwhile, TAC induced autophagic responses in heart, i.e. increases in autophagic structures, expression of Atg5 and Atg16 L1 mRNAs and LC3-II and Beclin-1 proteins. These pathological alterations in TAC-mice were significantly ameliorated or blocked by ALK administration. In TAC-mice, 3-methyladenine administration also ameliorated heart hypertrophy, fibrosis and dysfunction, while LY333531 administration inhibited ERK phosphorylation and autophagy in heart. In mechanically stretched cardiomyocytes, CGP53353 (a PKCβI inhibitor) prevented ERK phosphorylation and autophagic responses, while U0126 (an ERK inhibitor) blocked autophagic responses.

Conclusion: ALK ameliorates heart hypertrophy, fibrosis and dysfunction in the mouse model in setting of chronic pressure overload, via suppressing Ang II-PKCβI-ERK1/2-regulated autophagy.

Show MeSH
Related in: MedlinePlus