Up-regulation of p27^kip1 contributes to Nrf2-mediated protection against angiotensin II-induced cardiac hypertrophy

AimsNuclear factor erythroid-2-related factor 2 (Nrf2) appears to be a negative regulator of maladaptive cardiac remodelling and dysfunction; however, a potential of the Nrf2-mediated cardiac protection in diverse pathological settings remains to be determined. This study was aimed to explore the role of Nrf2 in angiotensin II (Ang II)-induced cardiac hypertrophy.Methods and resultsLittermate wild-type (WT) and Nrf2 knockout (Nrf2^-/-) mice were administered Ang II via osmotic mini-pumps for 2 weeks to induce cardiac hypertrophy. Elevation of blood pressure by the continuous Ang II infusion was comparable between WT and Nrf2^-/- mice. Relative to WT mice, however, Nrf2^-/- mice exhibited exaggerated myocardial oxidative stress with an impaired induction of a group of antioxidant genes and increased cardiac hypertrophy in response to the sustained Ang II stimulation. In cultured cardiomyocytes, adenoviral overexpression of Nrf2 shRNA enhanced Ang II-induced reactive oxygen species (ROS) production and protein synthesis, whereas adenoviral overexpression of Nrf2 exerted opposite effects. Moreover, Nrf2 deficiency exacerbated Ang II-induced down-regulation of p27^kip1 expression in the heart via a mechanism of post-transcriptional regulation. In contrast, adenoviral overexpression of Nrf2 increased p27^kip1 protein but not mRNA expression and reversed Ang II-induced down-regulation of p27 ^kip1 protein expression in cultured cardiomyocytes by suppressing ROS formation. Finally, the enhancement of Ang II-induced hypertrophic growth due to the Nrf2 deficiency was negated by overexpressing p27^kip1 in cultured cardiomyocytes.ConclusionThe Nrf2-p27^kip1 pathway serves as a novel negative feedback mechanism in Ang II-induced pathogenesis of cardiac hypertrophy, independent of changes in blood pressure.