CYP2J2 and its metabolites (EETs) attenuate cardiac hypertrophy by activating AMPKα2 and enhancing nuclear translocation of Akt1 / 中国病理生理杂志

ABSTRACT

AIM:Cytochrome P450 epoxygenase 2J2 and epoxyeicosatrienoic acids ( EETs) are known to protect against cardiac hypertrophy and heart failure, which involve activation of 5′-AMP-activated protein kinase ( AMPK) and Akt.Although the functional roles of AMPK and Akt are well established , the significance of crosstalk between them in the development of cardiac hypertrophy and anti -hy-pertrophy of CYP2J2 and EETs remains unclear .Here, we investigated whether CYP 2J2 and its metabolites EETs protected against cardiac hypertrophy by activating AMPKα2 and Akt1.Moreover, we tested whether EETs enhanced crosstalk between AMPKα2 and phosphorylated Akt1 ( p-Akt1), and stimulated the nuclear translocation of p-Akt1, to exert their anti-hypertrophic effects. METHODS:The recombinant rAAV9 vector was coupled to CYP2J2 and the rAAV9-CYP2J2 construct was injected into the caudal vein of AMPKα2-/-and littermate control mice .AMPKα2 -/-and littermate control mice that overexpressed CYP 2J2 in heart were treated with angiotensin II (Ang II) for 2 weeks.Hemodynamic and cardiac functions were also evaluated after 14 days of infusion with Ang II or saline.RESULTS:Interestingly, the overexpression of CYP2J2 suppressed cardiac hypertrophy , including decreased heart size, cross sectional area of cardiomyocytes , markers of cardiac hypertrophy [ brain natriuretic peptide ( BNP) ,β-myosin heavy chain (β-MHC) and skeletal muscle α-actin (ACTA1)] and increased levels of atrial natriuretic peptide (ANP) in the heart tissue and plasma of wild-type mice but not AMPKα2 -/-mice.Measurement of left ventricular ejection fraction and fractional shortening showed that CYP2J2 overexpression prevented Ang II-induced ventricular systolic dysfunction in mice .Moreover, an Ang II-induced reduction in cardiac function, demonstrated by decreased dp/dtmax and dp/dtmin, was prevented by overexpression of CYP2J2.Mechanistically, the CYP2J2 metabolites 11,12-EET activated AMPKα2 to induce the nuclear translocation of p-Akt1, which increased production of ANP and thereby inhibited the development of cardiac hypertrophy .Furthermore , by co-immunoprecipitation analysis , we found that full-length Akt1 and an Akt1 fragment containing amino acids 150-408, which constitute the protein kinase domain , but not other frag-ments of Akt1, bind to the AMPKγ1 subunit.AMPKα2β2γ1 and p-Akt1 interact through the direct binding of the AMPKγ1 subunit to the Akt1 protein kinase domain.This interaction was enhanced by 11,12-EET.CONCLUSION:Our studies reveal a novel mechanism in which CYP2J2 and EETs enhanced Akt1 nuclear translocation through interaction with AMPKα2β2γ1 and protect against cardiac hy-pertrophy and suggest that overexpression of CYP 2J2 might have clinical potential to suppress cardiac hypertrophy and heart failure .