Deficiency of NOX1/Nicotinamide Adenine Dinucleotide Phosphate, Reduced Form Oxidase Leads to Pulmonary Vascular Remodeling

• DOI: 10.1161/atvbaha.113.302107
• Publication Date: 2013-11-15T05:58:19Z
• Authors: Kazumi Iwata; Kanako Ikami; Kuniharu Matsuno; Toshiharu Yamashita; Dai Shiba; Masakazu Ibi; Misaki Matsumoto; Masato Katsuyama; Wenhao Cui; Jia Zhang; Kai Zhu; Norio Takei; Yasuo Kokai; Osamu Ohneda; Takahiko Yokoyama; Chihiro Yabe-Nish...
• Keywords: Male; Mice, Knockout; 0301 basic medicine; Hypertrophy, Right Ventricular; Hypertension, Pulmonary; Myocytes, Smooth Muscle; Hemodynamics; Apoptosis; Mice, Transgenic; Hypertrophy; Actins; Muscle, Smooth, Vascular; 3. Good health; Mice, Inbred C57BL; Disease Models, Animal; Kv1.5 Potassium Channel; Mice; 03 medical and health sciences; Animals; Familial Primary Pulmonary Hypertension; Genetic Predisposition to Disease; NADH, NADPH Oxidoreductases; Cells, Cultured

Objective—

Involvement of reactive oxygen species derived from nicotinamide adenine dinucleotide phosphate, reduced form (NADPH) oxidase has been documented in the development of hypoxia-induced model of pulmonary arterial hypertension (PAH). Because the PAH-like phenotype was demonstrated in mice deficient in Nox1 gene (Nox1 −/Y ) raised under normoxia, the aim of this study was to clarify how the lack of NOX1/NADPH oxidase could lead to pulmonary pathology.

Approach and Results—

Spontaneous enlargement and hypertrophy of the right ventricle, accompanied by hypertrophy of pulmonary vessels, were demonstrated in Nox1 −/Y 9 to 18 weeks old. Because an increased number of α-smooth muscle actin-positive vessels were observed in Nox1 −/Y , pulmonary arterial smooth muscle cells (PASMCs) were isolated and characterized by flow cytometry and terminal deoxynucleotidyl transferase dUTP nick end labeling staining. In Nox1 −/Y PASMCs, the number of apoptotic cells was significantly reduced without any change in the expression of endothelin-1, and hypoxia-inducible factors HIF-1α and HIF-2α, factors implicated in the pathogenesis of PAH. A significant decrease in a voltage-dependent K + channel, Kv1.5 protein, and an increase in intracellular potassium levels were demonstrated in Nox1 −/Y PASMCs. When a rescue study was performed in Nox1 −/Y crossed with transgenic mice overexpressing rat Nox1 gene, impaired apoptosis and the level of Kv1.5 protein in PASMCs were almost completely recovered in Nox1 −/Y harboring the Nox1 transgene.

Conclusions— These findings suggest a critical role for NOX1 in cellular apoptosis by regulating Kv1.5 and intracellular potassium levels. Because dysfunction of Kv1.5 is among the features demonstrated in PAH, inactivation of NOX1/NADPH oxidase may be a causative factor for pulmonary vascular remodeling associated with PAH.