Microsoft Word - 279760-R2_PAP_12_27_12

Subject codes: [15] Hypertrophy [91] Oxidative stress [148] Heart failure basic studies In November 2012, the average time from submission to first decision for all original research papers submitted to Circulation Research was 15.8 days. ABSTRACT Rationale: Oxidation of cysteine residues in class II histone deacetylases (HDACs), including HDAC4, causes nuclear exit, thereby inducing cardiac hypertrophy. The cellular source of reactive oxygen species (ROS) responsible for oxidation of HDAC4 remains unknown. Objective: We investigated whether Nox4, a major NADPH oxidase, mediates cysteine oxidation of HDAC4. an adrenergic agonist, induced upregulation of Nox4 (1.5-fold, p<0.05) within 5 min, accompanied by increases in O 2-(3.5-fold, p<0.01) from the nuclear membrane and nuclear exit of HDAC4 in cardiomyocytes (CM). Knockdown of Nox4, but not Nox2, attenuated O 2-production in the nucleus and prevented PE-induced oxidation and nuclear exit of HDAC4. After continuous infusion of PE (20 mg/kg/day) for 14 days, wild-type (WT) and cardiac-specific Nox4 knockout (c-Nox4 KO) mice exhibited similar aortic pressures. Left ventricular (LV) weight/ tibial length (5.7±0.2 vs. 6.4±0.2 mg/mm, p<0.05) and CM cross-sectional area (223±13 vs. 258±12 m 2 , p<0.05) were significantly smaller in c-Nox4 KO than in WT mice. Nuclear O 2-production in the heart was significantly lower in c-Nox4 KO than in WT mice (4116±314 vs. 7057±1710 RLU, p<0.05), and cysteine oxidation of HDAC4 was decreased. HDAC4 oxidation and cardiac hypertrophy were also attenuated in c-Nox4 KO mice 2 weeks after transverse aortic constriction. Conclusions: Nox4 plays an essential role in mediating cysteine oxidation and nuclear exit of HDAC4, thereby mediating cardiac hypertrophy in response to PE and pressure overload.