Endothelin-1 Depletion of Cartilage Oligomeric Matrix Protein Modulates Pulmonary Artery Superoxide and Iron Metabolism-associated Mitochondrial Heme Biosynthesis

This study examines if heme biosynthesis associated iron metabolism is regulated in pulmonary arteries by endothelin-1 (ET1) potentially through modulating Cartilage Oligomeric Matrix Protein (COMP) availability. Our studies in organoid cultured endothelium-rubbed bovine pulmonary arteries (BPA) observed COMP depletion by siRNA or hypoxia increases NOX2 and superoxide, and depletes mitochondrial SOD2. ET1 also increases superoxide in a manner that potentially impairs mitochondrial heme biosynthesis. In this study, organoid culture of BPA with ET1 (10nM) increases superoxide in the mitochondrial matrix and extra mitochondrial regions associated with COMP depletion, and COMP (0.5μM) inhibited these superoxide increases. Since mitochondrial matrix superoxide could impair heme biosynthesis from protoporphyrin IX (PpIX) by decreasing Fe2+ availability and/or ferrochelatase (FECH), we studied ET1, COMP and COMP siRNA effects on the expression of FECH, transferrin receptor-1 (TfR1, an indicator of iron availability) and soluble guanylate cyclase (sGC, a key heme-dependent protein), and on measurements of PpIX (HPLC) and heme content. ET1 decreased FECH, heme and sGC, and increased TfR1 and iron. COMP reversed these effects of ET1, and COMP decreased PpIX and increased heme in the absence of ET1. COMP siRNA increased PpIX detection and TfR1 expression, and decreased the expression of FECH and sGC. Nitric oxide (spermine NONOate) relaxation of BPA was inhibited by ET1, and this was a...
Source: Am J Physiol Lung Ce... - Category: Respiratory Medicine Authors: Source Type: research