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Reactive Oxygen Species Mediate Decreased Pulmonary Arterial Smooth Muscle Cell Membrane Cholesterol Following Chronic Hypoxia
Author(s) -
Ahmadian Rosstin,
Naik Jay,
Walker Benjimen,
Jernigan Nikki,
Resta Thomas
Publication year - 2021
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.2021.35.s1.03661
Subject(s) - hypoxic pulmonary vasoconstriction , cholesterol , filipin , hypoxia (environmental) , reactive oxygen species , medicine , caveolae , endocrinology , chemistry , biology , vasoconstriction , cell , oxygen , biochemistry , organic chemistry
Pulmonary arterial constriction and remodeling resulting from chronic hypoxia (CH) lead to increased pulmonary vascular resistance and resultant pulmonary hypertension (PH) in patients with chronic obstructive pulmonary diseases, sleep apnea, or in residents at high altitude. Recent studies from our laboratory have demonstrated a novel paradigm of CH‐induced vasoconstriction and PH mediated by an epidermal growth factor receptor‐NADPH oxidase 2‐RhoA Ca 2+ sensitization pathway in pulmonary arterial smooth muscle cells (PASMCs). We have further demonstrated a central role for decreased PASMC membrane cholesterol in this response. However, the mechanism by which CH lowers cholesterol is unknown. Since CH has an effect to both increase reactive oxygen species (ROS) in PASMC and decrease membrane cholesterol, we hypothesized that elevated ROS production during CH diminishes PASMC membrane cholesterol. To test this hypothesis, PASMC were collected from control and CH Sprague Dawley Rats (4 wk, P B = 0.5 atm, N=7‐9/group). After 3 days in cell culture, PASMC were treated with the ROS scavengers Tiron (10 mM), EUK‐134 (EUK) (10 mM), or their respective vehicles for 30 minutes. PASMC membrane cholesterol was quantified with the fluorescent cholesterol marker filipin (50 mg/ml) via confocal microscopy. A two‐way ANOVA was used to make comparisons and if differences were detected, individual groups were compared using the Tukey's multiple comparisons test. A probability of P < 0.05 was considered significant for comparisons. In agreement with our hypothesis, the CH‐dependent reduction in PASMC membrane cholesterol was acutely reversed following treatment with the ROS scavengers Tiron ( Figure 1A ) and EUK ( Figure 1B ). We conclude that ROS mediate CH‐dependent decreases in PASMC membrane cholesterol following CH exposure. These findings may provide a mechanistic basis by which CH links vasoconstrictor stimuli to EGFR signaling and resultant pulmonary hypertension. Future directions will explore the mechanism by which ROS mediate this response, including cholesterol oxidation or dysregulation of membrane cholesterol trafficking.