title: ERp29 regulates DeltaF508 and wild-type cystic fibrosis transmembrane conductance regulator (CFTR) trafficking to the plasma membrane in cystic fibrosis (CF) and non-CF epithelial cells.
abstract: Sodium 4-phenylbutyrate (4PBA) improves the intracellular trafficking of ΔF508-CFTR in cystic fibrosis (CF) epithelial cells. The underlying mechanism is uncertain, but 4PBA modulates the expression of some cytosolic molecular chaperones. To identify other 4PBA-regulated proteins that might regulate ΔF508-CFTR trafficking, we performed a differential display RT-PCR screen on IB3-1 CF bronchiolar epithelial cells exposed to 4PBA. One transcript up-regulated by 4PBA encoded ERp29, a luminal resident of the endoplasmic reticulum (ER) thought to be a novel molecular chaperone. We tested the hypothesis that ERp29 is a 4PBA-regulated ER chaperone that influences ΔF508-CFTR trafficking. ERp29 mRNA and protein expression was significantly increased (∼1.5-fold) in 4PBA-treated IB3-1 cells. In Xenopus oocytes, ERp29 overexpression increased the functional expression of both wild-type and ΔF508-CFTR over 3-fold and increased wild-type cystic fibrosis transmembrane conductance regulator (CFTR) plasma membrane expression. In CFBE41o- WT-CFTR cells, expression of and short circuit currents mediated by CFTR decreased upon depletion of ERp29 as did maturation of newly synthesized CFTR. In IB3-1 cells, ΔF508-CFTR co-immunoprecipitated with endogenous ERp29, and overexpression of ERp29 led to increased ΔF508-CFTR expression at the plasma membrane. These data suggest that ERp29 is a 4PBA-regulated ER chaperone that regulates WT-CFTR biogenesis and can promote ΔF508-CFTR trafficking in CF epithelial cells.
authors.affiliation: Division of Pulmonary Medicine and Cystic Fibrosis Center, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania 19104, USA.
authors.forename: Laurence
authors.initials: L
authors.lastname: Suaud
authors.forename: Katelyn
authors.initials: K
authors.lastname: Miller
authors.forename: Lora
authors.initials: L
authors.lastname: Alvey
authors.forename: Wusheng
authors.initials: W
authors.lastname: Yan
authors.forename: Amal
authors.initials: A
authors.lastname: Robay
authors.forename: Catherine
authors.initials: C
authors.lastname: Kebler
authors.forename: James L
authors.initials: JL
authors.lastname: Kreindler
authors.forename: Susan
authors.initials: S
authors.lastname: Guttentag
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Hubbard
authors.forename: Ronald C
authors.initials: RC
authors.lastname: Rubenstein
mesh_terms: D000818:Animals; D019921:Biotinylation; D002462:Cell Membrane / Q000378:metabolism*; D003550:Cystic Fibrosis / Q000378:metabolism*; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000378:metabolism*; D004594:Electrophysiology / Q000379:methods; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D004847:Epithelial Cells / Q000378:metabolism*; D006360:Heat-Shock Proteins / Q000378:metabolism*; D006801:Humans; D007477:Ions / Q000737:chemistry; D009865:Oocytes / Q000378:metabolism; D010654:Phenylbutyrates / Q000494:pharmacology; D021381:Protein Transport; D014981:Xenopus
chemical_list: C491738:ERP29 protein, human; D006360:Heat-Shock Proteins; D007477:Ions; D010654:Phenylbutyrates; C093349:cystic fibrosis transmembrane conductance regulator delta F508; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; C075773:4-phenylbutyric acid