title: Failure of bone morphogenetic protein receptor trafficking in pulmonary arterial hypertension: potential for rescue.
abstract: Heterozygous germline mutations in the gene encoding the bone morphogenetic protein type II receptor cause familial pulmonary arterial hypertension (PAH). We previously demonstrated that the substitution of cysteine residues in the ligand-binding domain of this receptor prevents receptor trafficking to the cell membrane. Here we demonstrate the potential for chemical chaperones to rescue cell-surface expression of mutant BMPR-II and restore function. HeLa cells were transiently transfected with BMPR-II wild type or mutant (C118W) receptor constructs. Immunolocalization studies confirmed the retention of the cysteine mutant receptor mainly in the endoplasmic reticulum. Co-immunoprecipitation studies of Myc-tagged BMPR-II confirmed that the cysteine-substituted ligand-binding domain mutation, C118W, is able to associate with BMP type I receptors. Furthermore, following treatment with a panel of chemical chaperones (thapsigargin, glycerol or sodium 4-phenylbutyrate), we demonstrated a marked increase in cell-surface expression of mutant C118W BMPR-II by FACS analysis and confocal microscopy. These agents also enhanced the trafficking of wild-type BMPR-II, though to a lesser extent. Increased cell-surface expression of mutant C118W BMPR-II was associated with enhanced Smad1/5 phosphorylation in response to BMPs. These findings demonstrate the potential for rescue of mutant BMPR-II function from the endoplasmic reticulum. For the C118W mutation in the ligand-binding domain of BMPR-II, cell-surface rescue leads to at least partial restoration of BMP signalling. We conclude that enhancement of cell-surface trafficking of mutant and wild-type BMPR-II may have therapeutic potential in familial PAH.
authors.affiliation: Department of Medicine, University of Cambridge School of Clinical Medicine, Box 157, Addenbrooke's Hospital, Hills Road, Cambridge, Cambridgeshire CB2 2QQ, UK.
authors.forename: Anastasia
authors.initials: A
authors.lastname: Sobolewski
authors.forename: Nung
authors.initials: N
authors.lastname: Rudarakanchana
authors.forename: Paul D
authors.initials: PD
authors.lastname: Upton
authors.forename: Jun
authors.initials: J
authors.lastname: Yang
authors.forename: Trina K
authors.initials: TK
authors.lastname: Crilley
authors.forename: Richard C
authors.initials: RC
authors.lastname: Trembath
authors.forename: Nicholas W
authors.initials: NW
authors.lastname: Morrell
mesh_terms: D019943:Amino Acid Substitution; D001693:Biological Transport, Active / Q000187:drug effects; D052005:Bone Morphogenetic Protein Receptors, Type I / Q000378:metabolism; D052006:Bone Morphogenetic Protein Receptors, Type II / Q000235:genetics* / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000187:drug effects / Q000378:metabolism; D018095:Germ-Line Mutation; D005990:Glycerol / Q000494:pharmacology; D006367:HeLa Cells; D006801:Humans; D006976:Hypertension, Pulmonary / Q000188:drug therapy / Q000235:genetics* / Q000378:metabolism*; D008954:Models, Biological; D010654:Phenylbutyrates / Q000494:pharmacology; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D051896:Smad Proteins, Receptor-Regulated / Q000378:metabolism; D019284:Thapsigargin / Q000494:pharmacology; D014162:Transfection
chemical_list: D010654:Phenylbutyrates; D011994:Recombinant Proteins; D051896:Smad Proteins, Receptor-Regulated; D019284:Thapsigargin; C075773:4-phenylbutyric acid; C498218:BMPR2 protein, human; D052005:Bone Morphogenetic Protein Receptors, Type I; D052006:Bone Morphogenetic Protein Receptors, Type II; D005990:Glycerol