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COPII-dependent export of cystic fibrosis transmembrane conductance regulator from the ER uses a di-acidic exit code.

Wang X, Matteson J, An Y, Moyer B, Yoo JS, Bannykh S, Wilson IA, Riordan JR, Balch WE - J. Cell Biol. (2004)

Bottom Line: In contrast, COPII is not used to deliver CFTR to ER-associated degradation.Mutation of the code disrupts interaction with the COPII coat selection complex Sec23/Sec24.We propose that the di-acidic exit code plays a key role in linking CFTR to the COPII coat machinery and is the primary defect responsible for CF in DeltaF508-expressing patients.

View Article: PubMed Central - PubMed

Affiliation: Department of Cell Biology, The Scripps Research Institute, La Jolla, CA 92037, USA.

ABSTRACT
Cystic fibrosis (CF) is a childhood hereditary disease in which the most common mutant form of the CF transmembrane conductance regulator (CFTR) DeltaF508 fails to exit the endoplasmic reticulum (ER). Export of wild-type CFTR from the ER requires the coat complex II (COPII) machinery, as it is sensitive to Sar1 mutants that disrupt normal coat assembly and disassembly. In contrast, COPII is not used to deliver CFTR to ER-associated degradation. We find that exit of wild-type CFTR from the ER is blocked by mutation of a consensus di-acidic ER exit motif present in the first nucleotide binding domain. Mutation of the code disrupts interaction with the COPII coat selection complex Sec23/Sec24. We propose that the di-acidic exit code plays a key role in linking CFTR to the COPII coat machinery and is the primary defect responsible for CF in DeltaF508-expressing patients.

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Export of CFTR from the ER but not degradation is inhibited by the kinase inhibitor H89. BHK cells stably expressing either wild-type CFTR or ΔF508-CFTR were labeled with [35S]Met for 30 min as described previously (Yoo et al., 2002). After labeling, cells were chased for the indicated time in the absence or presence of 50 μM H89, and processing of CFTR from the band B ER form to mature band C was quantitated as described previously (Yoo et al., 2002). Results are typical of two independent experiments.
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fig2: Export of CFTR from the ER but not degradation is inhibited by the kinase inhibitor H89. BHK cells stably expressing either wild-type CFTR or ΔF508-CFTR were labeled with [35S]Met for 30 min as described previously (Yoo et al., 2002). After labeling, cells were chased for the indicated time in the absence or presence of 50 μM H89, and processing of CFTR from the band B ER form to mature band C was quantitated as described previously (Yoo et al., 2002). Results are typical of two independent experiments.

Mentions: To provide additional evidence for the role of Sar1 in selection of wild-type CFTR for export, we took advantage of the protein kinase inhibitor H89 that we have previously shown to inhibit Sar1 recruitment and COPII coat assembly (Aridor and Balch, 2000). Addition of H89 to cells stably expressing CFTR strongly reduced export (90%; Fig. 2). ERAD continues efficiently, suggesting that COPII recruitment is not required for targeting for degradation as H89, like Sar1-GDP, uncouples cargo from the COPII coat machinery (Aridor and Balch, 2000).


COPII-dependent export of cystic fibrosis transmembrane conductance regulator from the ER uses a di-acidic exit code.

Wang X, Matteson J, An Y, Moyer B, Yoo JS, Bannykh S, Wilson IA, Riordan JR, Balch WE - J. Cell Biol. (2004)

Export of CFTR from the ER but not degradation is inhibited by the kinase inhibitor H89. BHK cells stably expressing either wild-type CFTR or ΔF508-CFTR were labeled with [35S]Met for 30 min as described previously (Yoo et al., 2002). After labeling, cells were chased for the indicated time in the absence or presence of 50 μM H89, and processing of CFTR from the band B ER form to mature band C was quantitated as described previously (Yoo et al., 2002). Results are typical of two independent experiments.
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Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2172508&req=5

fig2: Export of CFTR from the ER but not degradation is inhibited by the kinase inhibitor H89. BHK cells stably expressing either wild-type CFTR or ΔF508-CFTR were labeled with [35S]Met for 30 min as described previously (Yoo et al., 2002). After labeling, cells were chased for the indicated time in the absence or presence of 50 μM H89, and processing of CFTR from the band B ER form to mature band C was quantitated as described previously (Yoo et al., 2002). Results are typical of two independent experiments.
Mentions: To provide additional evidence for the role of Sar1 in selection of wild-type CFTR for export, we took advantage of the protein kinase inhibitor H89 that we have previously shown to inhibit Sar1 recruitment and COPII coat assembly (Aridor and Balch, 2000). Addition of H89 to cells stably expressing CFTR strongly reduced export (90%; Fig. 2). ERAD continues efficiently, suggesting that COPII recruitment is not required for targeting for degradation as H89, like Sar1-GDP, uncouples cargo from the COPII coat machinery (Aridor and Balch, 2000).

Bottom Line: In contrast, COPII is not used to deliver CFTR to ER-associated degradation.Mutation of the code disrupts interaction with the COPII coat selection complex Sec23/Sec24.We propose that the di-acidic exit code plays a key role in linking CFTR to the COPII coat machinery and is the primary defect responsible for CF in DeltaF508-expressing patients.

View Article: PubMed Central - PubMed

Affiliation: Department of Cell Biology, The Scripps Research Institute, La Jolla, CA 92037, USA.

ABSTRACT
Cystic fibrosis (CF) is a childhood hereditary disease in which the most common mutant form of the CF transmembrane conductance regulator (CFTR) DeltaF508 fails to exit the endoplasmic reticulum (ER). Export of wild-type CFTR from the ER requires the coat complex II (COPII) machinery, as it is sensitive to Sar1 mutants that disrupt normal coat assembly and disassembly. In contrast, COPII is not used to deliver CFTR to ER-associated degradation. We find that exit of wild-type CFTR from the ER is blocked by mutation of a consensus di-acidic ER exit motif present in the first nucleotide binding domain. Mutation of the code disrupts interaction with the COPII coat selection complex Sec23/Sec24. We propose that the di-acidic exit code plays a key role in linking CFTR to the COPII coat machinery and is the primary defect responsible for CF in DeltaF508-expressing patients.

Show MeSH
Related in: MedlinePlus