Increased Oxidative Stress in the Nucleus Caused by Nox4 Mediates Oxidation of HDAC4 and Cardiac Hypertrophy

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. Methods and Results Phenylephrine (PE, 100 μM), an α1 adrenergic agonist, induced upregulation of Nox4 (1.5-fold, p<0.05) within 5 min, accompanied by increases in O2− (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 O2− 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 μm2, p<0.05) were significantly smaller in c-Nox4 KO than in WT mice. Nuclear O2− 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.

NADPH Oxidase-generated Hydrogen Peroxide Induces DNA Damage in Mutant FLT3-expressing Leukemia Cells

“…NOX4 and p22 phox Colocalized to the Nuclear Membrane in MV4-11-Given that NOX4 knockdown caused a decrease in both H 2 O 2 and DNA damage, we investigated if NOX4 localizes to the nucleus as previously shown in the literature in other cell types (31)(32)(33). We observed no clear NOX4 foci in the nucleus (Fig.…”

“…Up to now, NOX4 have been localized to mitochondria (41,42), nucleus (31)(32)(33), ER (43)(44)(45)(46), and plasma membrane (45). Here for the first time, we localize NOX4 expression in FLT3-ITD expressing cells.…”

“…For instance, in cardiomyocytes, NOX4-produced H 2 O 2 was also observed to specifically oxidize nuclear proteins, e.g. histone deacetylase (33). Also, NOX4, localized in the perinuclear space was also the source of nuclear superoxide generation in hepatocytes (38).…”

Cytosolic Accumulation of Small Nucleolar RNAs (snoRNAs) Is Dynamically Regulated by NADPH Oxidase

“…Cytosolic RNA was isolated by detergent extraction, and Rpl13a snoRNAs were quantified by qPCR (G). Rpl13a snoRNA localization (15,16). Using a previously validated siRNA knockdown approach for Nox4 isoforms (15), we used two independent siRNAs for each target: membrane-associated Nox4A at exons 3 or 5 (siRNA Nox4A), both the Nox4A and Nox4D isoforms at exons 12-13 or 14 (siRNA Nox4A/D), or the regulatory p22 subunit (Fig.…”

A class of their own: exploring the nondeacetylase roles of class IIa HDACs in cardiovascular disease

“…Matushima and colleagues (51) also elucidated that HDAC4 can be oxidized via intranuclear sources of reactive oxygen species on conserved, class IIa, cysteine residues (51). Oxidation of class IIa HDACs results in their exportation from the nucleus (51,74) (Fig. 1).…”