title: The lysosomal inhibitor, chloroquine, increases cell surface BMPR-II levels and restores BMP9 signalling in endothelial cells harbouring BMPR-II mutations.
abstract: Pulmonary arterial hypertension (PAH) is characterized by dysregulated pulmonary artery endothelial cell (PAEC) proliferation, apoptosis and permeability. Loss-of-function mutations in the bone morphogenetic protein receptor type-II (BMPR-II) are the most common cause of heritable PAH, usually resulting in haploinsufficiency. We previously showed that BMPR-II expression is regulated via a lysosomal degradative pathway. Here, we show that the antimalarial drug, chloroquine, markedly increased cell surface expression of BMPR-II protein independent of transcription in PAECs. Inhibition of protein synthesis experiments revealed a rapid turnover of cell surface BMPR-II, which was inhibited by chloroquine treatment. Chloroquine enhanced PAEC expression of BMPR-II following siRNA knockdown of the BMPR-II transcript. Using blood outgrowth endothelial cells (BOECs), we confirmed that signalling in response to the endothelial BMPR-II ligand, BMP9, is compromised in BOECs from patients harbouring BMPR-II mutations, and in BMPR-II mutant PAECs. Chloroquine significantly increased gene expression of BMP9-BMPR-II signalling targets Id1, miR21 and miR27a in both mutant BMPR-II PAECs and BOECs. These findings provide support for the restoration of cell surface BMPR-II with agents such as chloroquine as a potential therapeutic approach for heritable PAH.
authors.affiliation: Division of Respiratory Medicine, Department of Medicine, University of Cambridge School of Clinical Medicine, Addenbrooke's and Papworth Hospitals, Cambridge, UK.
authors.forename: Benjamin J
authors.initials: BJ
authors.lastname: Dunmore
authors.forename: Kylie M
authors.initials: KM
authors.lastname: Drake
authors.forename: Paul D
authors.initials: PD
authors.lastname: Upton
authors.forename: Mark R
authors.initials: MR
authors.lastname: Toshner
authors.forename: Micheala A
authors.initials: MA
authors.lastname: Aldred
authors.forename: Nicholas W
authors.initials: NW
authors.lastname: Morrell
mesh_terms: D052006:Bone Morphogenetic Protein Receptors, Type II / Q000235:genetics* / Q000378:metabolism*; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D002738:Chloroquine / Q000494:pharmacology* / Q000627:therapeutic use; D042783:Endothelial Cells / Q000378:metabolism*; D065627:Familial Primary Pulmonary Hypertension; D055427:Growth Differentiation Factor 2; D055412:Growth Differentiation Factors / Q000378:metabolism*; D006801:Humans; D006976:Hypertension, Pulmonary / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism; D008247:Lysosomes / Q000378:metabolism; D009154:Mutation; D011651:Pulmonary Artery / Q000166:cytology; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D051785:Smad Proteins / Q000378:metabolism; D014158:Transcription, Genetic
chemical_list: C525887:GDF2 protein, human; D055427:Growth Differentiation Factor 2; D055412:Growth Differentiation Factors; D034741:RNA, Small Interfering; D051785:Smad Proteins; D002738:Chloroquine; C498218:BMPR2 protein, human; D052006:Bone Morphogenetic Protein Receptors, Type II