FIGURE 7.

FKBP8 facilitates CFTR biogenesis. A, immunoblot (IB) analysis of CFTR, Hsp70, Hsp90, and FKBP8 following immunoprecipitation (IP) of ΔF508-CFTR (top) or WT-CFTR (bottom) and treatment of the respective CFBE cells with siFKBP8 or scramble control siRNA. Cells were treated at either 37 or 30 °C as indicated. Controls cells lacking CFTR are indicated by −/−. B, quantitative analysis of the recovery of Hsp70, Hsp90, and FKBP8 by co-immunoprecipitation of CFTR following treatment with siFKBP8 or scramble control for the indicated CFTR isoform. The 37 and 30 °C labels indicate ΔF508-CFTR following culture of the CFBE41o− cells at the indicated temperature. Data for Hsp70 and -90 are shown as a ratio to total CFTR. Data were then normalized to the scramble condition that was set to 1. FKBP8 data are shown as a ratio to band B (B). All data are shown as mean ± S.E. p values were determined using a two-tailed t test where asterisks indicate p ≤ 0.05 and pound signs indicate p ≤ 0.10. C, immunoblot analysis of CFTR and FKBP8 following immunoprecipitation of FKBP8 from CFBE cells expressing no CFTR (−/−), wild-type CFTR (WT), or ΔF508-CFTR at 37 or 30 °C. The left panels show the input for the experiment, and the right panels represent the immunoprecipitated material. D, immunoblot analysis of CFTR, Hsp90, and FKBP8 following immunoprecipitation of ΔF508-CFTR from CFBE41o− cells cultured at 37 °C using more stringent washing conditions to remove Hsp90/70 than shown in A. E, immunoblot analysis of CFTR, Hsp90, and FKBP8 following immunoprecipitation of ΔF508-CFTR from CFBE41o− cells treated with the FKBP8 inhibitor DM-CHX or Hepes control (“−”) at 37 °C. The samples were washed as in D. Cont, control.