title: Aberrant Caveolin-1-Mediated Smad Signaling and Proliferation Identified by Analysis of Adenine 474 Deletion Mutation (c.474delA) in Patient Fibroblasts: A New Perspective in the Mechanism of Pulmonary Hypertension.
abstract: A heterozygous Caveolin-1 c.474delA mutation has been identified in a family with heritable pulmonary arterial hypertension (PAH). This frameshift mutation leads to caveolin-1 protein that contains all known functional domains but has a change only in the final 20 amino acids of the C terminus. Here we studied how this mutation alters caveolin-1 function using patient-derived fibroblasts. Transmission electron microscopy showed that fibroblasts carrying the c.474delA mutation formed typical caveolae. Expression of mutated caveolin-1 in caveolin-1-null mouse fibroblasts failed to induce formation of caveolae due to retention of the mutated protein in the endoplasmic reticulum. However, co-expression of wild type caveolin-1 with mutated caveolin-1 restored the ability to form caveolae. Importantly, fibroblasts carrying the mutation showed 2-fold increase in proliferation rate associated with hyper-phosphorylation of Smad1/5/8. This mutation impaired the anti-proliferative function of caveolin-1. Inhibition of type I TGFβ receptors ALK1/2/3/6 responsible for phosphorylation of Smad1/5/8 reduced the hyper-proliferation seen in c.474delA fibroblasts. These results demonstrate the critical role of the final 20 amino acids of caveolin-1 in modulating fibroblast proliferation through dampening Smad signaling, and suggest that augmented Smad signaling and fibroblast hyper-proliferation are contributing factors in the pathogenesis of PAH in patients with caveolin-1 c.474delA mutation.
authors.affiliation: Department of Pharmacology, University of Illinois College of Medicine, Chicago, IL, United States of America.
authors.forename: Glenn
authors.initials: G
authors.lastname: Marsboom
authors.affiliation: Department of Anesthesiology, University of Illinois College of Medicine, Chicago, IL, United States of America.
authors.forename: Zhenlong
authors.initials: Z
authors.lastname: Chen
authors.affiliation: Department of Pharmacology, University of Illinois College of Medicine, Chicago, IL, United States of America.
authors.forename: Yang
authors.initials: Y
authors.lastname: Yuan
authors.affiliation: Department of Pharmacology, University of Illinois College of Medicine, Chicago, IL, United States of America.|Department of Pathology, University of Illinois College of Medicine, Chicago, IL, United States of America.
authors.forename: Yanmin
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Department of Pharmacology, University of Illinois College of Medicine, Chicago, IL, United States of America.
authors.forename: Chinnaswamy
authors.initials: C
authors.lastname: Tiruppathi
authors.affiliation: Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, United States of America.
authors.forename: James E
authors.initials: JE
authors.lastname: Loyd
authors.affiliation: Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN, United States of America.
authors.forename: Eric D
authors.initials: ED
authors.lastname: Austin
authors.affiliation: Department of Pharmacology, University of Illinois College of Medicine, Chicago, IL, United States of America.|Department of Medicine, University of Illinois College of Medicine, Chicago, IL, United States of America.
authors.forename: Roberto F
authors.initials: RF
authors.lastname: Machado
authors.affiliation: Department of Anesthesiology, University of Illinois College of Medicine, Chicago, IL, United States of America.
authors.forename: Richard D
authors.initials: RD
authors.lastname: Minshall
authors.affiliation: Department of Pharmacology, University of Illinois College of Medicine, Chicago, IL, United States of America.|Department of Medicine, University of Illinois College of Medicine, Chicago, IL, United States of America.
authors.forename: Jalees
authors.initials: J
authors.lastname: Rehman
authors.affiliation: Department of Pharmacology, University of Illinois College of Medicine, Chicago, IL, United States of America abmalik@uic.edu.
authors.forename: Asrar B
authors.initials: AB
authors.lastname: Malik