ABSTRACT
Cystic Fibrosis is a lethal monogenic autosomal recessive disease linked to mutations in Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) protein. The most frequent mutation is the deletion of phenylalanine at position 508 of the protein. This F508del-CFTR mutation leads to misfolded protein that is detected by the quality control machinery within the endoplasmic reticulum and targeted for destruction by the proteasome. Modulating quality control proteins as molecular chaperones is a promising strategy for attenuating the degradation and stabilizing the mutant CFTR at the plasma membrane. Among the molecular chaperones, the small heat shock protein HspB1 and HspB4 were shown to promote degradation of F508del-CFTR. Here, we investigated the impact of HspB5 expression and phosphorylation on transport to the plasma membrane, function and stability of F508del-CFTR. We show that a phosphomimetic form of HspB5 increases the transport to the plasma membrane, function and stability of F508del-CFTR. These activities are further enhanced in presence of therapeutic drugs currently used for the treatment of cystic fibrosis (VX-770/Ivacaftor, VX-770+VX-809/Orkambi). Overall, this study highlights the beneficial effects of a phosphorylated form of HspB5 on F508del-CFTR rescue and its therapeutic potential in cystic fibrosis.
Subject(s)
Cystic Fibrosis Transmembrane Conductance Regulator/metabolism , Molecular Chaperones/metabolism , Phenylalanine/metabolism , Phosphorylation/physiology , Aminophenols/pharmacology , Aminopyridines/pharmacology , Animals , Benzodioxoles/pharmacology , Cell Line , Cell Membrane/metabolism , Crystallins/metabolism , Cystic Fibrosis/genetics , Cystic Fibrosis/metabolism , Cystic Fibrosis Transmembrane Conductance Regulator/genetics , Drug Combinations , HEK293 Cells , Heat-Shock Proteins/metabolism , Humans , Male , Mice , Molecular Chaperones/genetics , Mutation/genetics , Phenylalanine/genetics , Phosphorylation/drug effects , Proteasome Endopeptidase Complex/metabolism , Protein Transport/drug effects , Protein Transport/genetics , Quinolones/pharmacologyABSTRACT
BACKGROUND: The observation that COPD is an independent risk factor for cardiovascular disease (CVDs) comes from comparisons between smokers with COPD and smokers without COPD. The mechanisms that explain increased risk of CVD in patients with COPD are still unclear. OBJECTIVES: The goal of this study was to assess systemic arterial stiffness (a predictor of CVD mortality) and to evaluate its determinants in a group of patients with mild to moderate COPD secondary to organic dust exposure, tobacco smoking, or both. METHODS: Systemic arterial stiffness was assessed by using aortic pulse wave velocity (aPWV). Measurements were made in 142 patients with COPD and 155 healthy control subjects matched for age, sex, BMI, and tobacco smoking, exposed to tobacco smoking (n = 56/70 for COPD/control subjects, respectively), organic dusts (n = 44/48), or both (n = 42/37). RESULTS: aPWV was higher in COPD than in healthy controls in subjects exposed to tobacco smoking and to both organic dusts and tobacco smoking. By contrast, among never smokers exposed to organic dusts, patients with COPD and matched control subjects had similar aPWV. Multivariate analysis of the 142 patients with COPD (exposed to tobacco smoking and/or to organic dusts) showed that tobacco smoking was associated with high aPWV. Moreover, soluble suppression of tumorigenicity 2, a marker of major cardiovascular events, was correlated with aPWV in these patients. CONCLUSIONS: Analysis of an unselected group of patients with COPD with different causes suggests that: (1) COPD by itself is not sufficient to explain increased aPWV; and (2) tobacco smoking is a risk factor for elevated aPWV in COPD.
