Neprilysin Peptidase‐Independent Complex Formation In Pulmonary Artery Smooth Muscle Cells

Abstract

Pulmonary hypertension (PHTN) results from vasoconstriction and remodeling of pulmonary arteries (PA), including accumulation and migration of smooth muscle cells (SMCs). We found that the activity/expression of the transmembrane peptidase neprilysin (NEP) is decreased in chronic hypoxic PHTN, and that chronically hypoxic NEP null mice have increased pulmonary vascular remodeling. We hypothesize that, besides peptidase effects, the peptidase‐independent mechanisms of NEP, mediated through coupling of NEP to intracellular proteins, are important in mediating the effects of NEP in PA SMCs.Silver‐stained gels of C57BL/6 wt mouse PA SMCs, co‐immunoprecipitated with an antibody to NEP, show bands of 40, 55, 65, 75, 90 and 150 kD. Western analyses (n=2–5) show that NEP forms complexes with the MAPK ERK1/2 and the protein kinase Lyn. Human PA SMCs show similar results. Future studies will investigate the growth‐ and migratory‐inhibitory properties of these complexes, as well as characterize NEP complexes with other proteins. These findings indicate that peptidase‐independent mechanisms may contribute to the mechanisms of action of NEP and may aid in understanding NEP's involvement in preventing/reversing pulmonary vascular remodeling, and in designing treatment and prevention strategies for PHTN.Research Support: NHLBI RO1 HL‐078929‐01 and PPG HL‐014985, UCD Dept. of Medicine, and the VA.