PROCESSING OF MUTANT CYSTIC-FIBROSIS TRANSMEMBRANE CONDUCTANCE REGULATOR IS TEMPERATURE-SENSITIVE
PROCESSING OF MUTANT CYSTIC-FIBROSIS TRANSMEMBRANE CONDUCTANCE REGULATOR IS TEMPERATURE-SENSITIVE
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DOI：
10.1038/358761a0
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发表时间：
1992-08-27
期刊：
影响因子：
64.8
通讯作者：
WELSH, MJ
中科院分区：
文献类型：
--
作者：
DENNING, GM;ANDERSON, MP;WELSH, MJ
囊性纤维化跨膜电导调节器 (CFTR) 是一种质膜 Cl-通道，受环 AMP 依赖性磷酸化和细胞内 ATP1-7 调节。 CFTR 突变导致囊性纤维化8-10，部分原因是受影响上皮质膜的cAMP 调节的Cl-通透性丧失11,12。囊性纤维化中最常见的突变是残基 508 处苯丙氨酸的缺失 (CFTR-DELTA-F508)（参考文献 10）。对 CFTR-DELTA-F508 生物合成 13,14 和定位 15 的研究表明，突变蛋白没有被正确加工，因此没有被递送到质膜。这些结论与早期的功能研究一致，这些研究未能在表达 CFTR-DELTA-F508 的细胞中检测到 cAMP 刺激的 Cl 通道（参考文献 16、17）。然而，当 CFTR-DELTA-F508 在非洲爪蟾卵母细胞 18、Vero 细胞 19 和 Sf9 昆虫细胞 20 中表达时，检测到氯离子通道活性。由于卵母细胞和 Sf9 细胞通常维持在比哺乳动物细胞更低的温度下，并且新生蛋白的加工对温度敏感21，因此我们测试了温度对 CFTR-DELTA-F508 加工的影响。在这里，我们表明，随着孵育温度的降低，CFTR-DELTA-F508 的加工恢复到野生型的加工。当处理缺陷得到纠正时，cAMP 调节的 Cl- 通道出现在质膜中。这些结果与之前相互矛盾的观察结果相一致，表明与囊性纤维化最常见的突变体是温度敏感的。
CYSTIC fibrosis transmembrane conductance regulator (CFTR) is a plasma membrane Cl- channel regulated by cyclic AMP-dependent phosphorylation and by intracellular ATP1-7. Mutations in CFTR cause cystic fibrosis8-10 partly through loss of cAMP-regulated Cl- permeability from the plasma membrane of affected epithelia11,12. The most common mutation in cystic fibrosis is deletion of phenylalanine at residue 508 (CFTR-DELTA-F508) (ref. 10). Studies on the biosynthesis13,14 and localization15 of CFTR-DELTA-F508 indicate that the mutant protein is not processed correctly and, as a result, is not delivered to the plasma membrane. These conclusions are consistent with earlier functional studies which failed to detect cAMP-stimulated Cl- channels in cells expressing CFTR-DELTA-F508 (refs 16, 17). Chloride channel activity was detected, however, when CFTR-DELTA-F508 was expressed in Xenopus oocytes18, Vero cells19 and Sf9 insect cells20. Because oocytes and Sf9 cells are typically maintained at lower temperatures than mammalian cells, and because processing of nascent proteins can be sensitive to temperature21, we tested the effect of temperature on the processing of CFTR-DELTA-F508. Here we show that the processing of CFTR-DELTA-F508 reverts towards that of wild-type as the incubation temperature is reduced. When the processing defect is corrected, cAMP-regulated Cl- channels appear in the plasma membrane. These results reconcile previous contradictory observations and suggest that the mutant most commonly associated with cystic fibrosis is temperature-sensitive.