ER-associated complexes (ERACs) containing aggregated cystic fibrosis transmembrane conductance regulator (CFTR) are degraded by autophagy
ER-associated complexes (ERACs) containing aggregated cystic fibrosis transmembrane conductance regulator (CFTR) are degraded by autophagy
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DOI：
10.1016/j.ejcb.2008.11.003
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发表时间：
2009-04-01
影响因子：
6.6
通讯作者：
Sztul, Elizabeth
中科院分区：
文献类型：
--
作者：
Fu, Lianwu;Sztul, Elizabeth
泛素-蛋白酶体途径和自噬是细胞蛋白质清除的两个主要机制。我们使用酵母酿酒酵母作为模型系统和囊性纤维化跨膜传导调节因子（CFTR）作为模型底物，研究这两个途径在降解错误折叠蛋白质中的相互作用。将EGFP标记的人CFTR引入酵母并在铜诱导型启动子下表达。EGFP-CFTR在活细胞中的定位和降解在其从头合成后通过延时成像监测。EGFP-CFTR首先出现在核周和皮质下ER内。并且通过光漂白后荧光恢复（FRAP）评估，在膜平面内是移动的。该EGFP-CFTR库随后通过蛋白酶体依赖性途径降解，该途径在蛋白酶体降解缺陷的prel-1酵母菌株中受到抑制。EGFP-CFTR的延长表达导致EGFP-CFTR分子螯合到称为ER相关复合物（ERAC）的ER结构中。EGFP-CFTR螯合到ERAC中似乎是由聚集驱动的，因为如通过FRAP所测量的，ERAC内存在的EGFP-CFTR分子是不动的。单个ERAC通过自噬途径从细胞中清除，该途径在自噬缺陷的atg 6 Delta和atg 1 Delta酵母菌株中被阻断。我们的研究结果表明，蛋白酶体和自噬途径共同作用，以清除错误折叠的蛋白质从ER。由爱思唯尔有限公司出版。
The ubiquitin-proteasome pathway and autophagy are the two major mechanisms responsible for the clearance of cellular proteins. We have used the yeast Saccharomyces cerevisiae as a model system and the cystic fibrosis transmembrane conductance regulator (CFTR) as a model substrate to study the interactive function of these two pathways in the degradation of misfolded proteins. EGFP-tagged human CFTR was introduced into yeast and expressed under a copper-inducible promoter. The localization and degradation of EGFP-CFTR in live cells were monitored by time-lapse imaging following its de novo synthesis. EGFP-CFTR first appears within the perinuclear and sub-cortical ER. and is mobile within the plane of the membrane as assessed by fluorescence recovery after photobleaching (FRAP). This pool of EGFP-CFTR is subsequently degraded through a proteasome-dependent pathway that is inhibited in the prel-1 yeast strain defective in proteasomal degradation. Prolonged expression of EGFP-CFTR leads to the sequestration of EGFP-CFTR molecules into ER structures called ER-associated complexes (ERACs). The sequestration of EGFP-CFTR into ERACs appears to be driven by aggregation since EGFP-CFTR molecules present within ERACs are immobile as measured by FRAP. Individual ERACs are cleared from cells through the autophagic pathway that is blocked in the atg6 Delta and atg1 Delta yeast strains defective in autophagy. Our results suggest that the proteasomal and the autophagic pathways function together to clear misfolded proteins from the ER. Published by Elsevier GmbH.