Aberrant caveolin-1-mediated Smad signaling and proliferation identified by analysis of adenine 474 deletion mutation (c.474delA) in patient fibroblasts: A new perspective on the mechanism of pulmonary hypertension

Glenn Marsboom, Zhenlong Chen, Yang Yuan, Yanmin Zhang, Chinnaswamy Tiruppathi, James E. Loyd, Eric D. Austin, Roberto F. MacHado, Richard D. Minshall, Jalees Rehman, Asrar B. Malik

Research output: Contribution to journalArticle

9 Scopus citations

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 a caveolin- 1 protein that contains all known functional domains but has a change in only 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 form 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, coexpression of wild-type caveolin-1 with mutated caveolin-1 restored the ability to form caveolae. Importantly, fibroblasts carrying the mutation showed twofold increase in proliferation rate associated with hyperphosphorylation of Smad1/5/8. This mutation impaired the antiproliferative function of caveolin-1. Inhibition of type I TGFβ receptors ALK1/2/3/6 responsible for phosphorylation of Smad1/5/8 reduced the hyperproliferation seen in c.474delA fibroblasts. These results demonstrate the critical role of the final 20 amino acids of caveolin-1 in modulating fibroblast proliferation by dampening Smad signaling and suggest that augmented Smad signaling and fibroblast hyperproliferation are contributing factors in the pathogenesis of PAH in patients with caveolin-1 c.474delA mutation.

Original languageEnglish (US)
Pages (from-to)1177-1185
Number of pages9
JournalMolecular Biology of the Cell
Volume28
Issue number9
DOIs
StatePublished - May 1 2017
Externally publishedYes

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology

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