ERp29 Regulates Delta F508 and Wild-type Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) Trafficking to the Plasma Membrane in Cystic Fibrosis (CF) and Non-CF Epithelial Cells

作者：Suaud Laurence; Miller Katelyn; Alvey Lora; Yan Wusheng; Robay Amal; Kebler Catherine; Kreindler James L; Guttentag Susan; Hubbard Michael J; Rubenstein Ronald C^*

来源：Journal of Biological Chemistry, 2011, 286(24): 21239-21253.

DOI：10.1074/jbc.M111.240267

Sodium 4-phenylbutyrate (4PBA) improves the intracellular trafficking of Delta F508-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 Delta F508-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 Delta F508-CFTR trafficking. ERp29 mRNA and protein expression was significantly increased (similar to 1.5-fold) in 4PBA-treated IB3-1 cells. In Xenopus oocytes, ERp29 overexpression increased the functional expression of both wild-type and Delta F508-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, Delta F508-CFTR co-immunoprecipitated with endogenous ERp29, and overexpression of ERp29 led to increased Delta F508-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 Delta F508-CFTR trafficking in CF epithelial cells.

• 出版日期2011-6-17