Published in:
01-04-2014 | Original Investigation
Overexpression of p62/SQSTM1 promotes the degradations of abnormally accumulated PrP mutants in cytoplasm and relieves the associated cytotoxicities via autophagy–lysosome-dependent way
Authors:
Yin Xu, Jin Zhang, Chan Tian, Ke Ren, Yu-E Yan, Ke Wang, Hui Wang, Cao Chen, Jing Wang, Qi Shi, Xiao-Ping Dong
Published in:
Medical Microbiology and Immunology
|
Issue 2/2014
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Abstract
The protein of p62/sequestosome 1 (SQSTM1), a key cargo adaptor protein involved in autophagy–lysosome degradation, exhibits inclusion bodies structure in cytoplasm and plays a protective role in some models of neurodegenerative diseases. Some PrP mutants, such as PrP-CYTO and PrP-PG14, also form cytosolic inclusion bodies and trigger neuronal apoptosis either in cultured cells or in transgenic mice. Here, we demonstrated that the cellular p62/SQSTM1 incorporated into the inclusion bodies formed by expressing the abnormal PrP mutants, PrP-CYTO and PrP-PG14, in human embryonic kidney 293 cells. Overexpression of p62/SQSTM1 efficiently relieved the cytosolic aggregations and cell apoptosis induced by the abnormal PrPs. Autophagy–lysosome inhibitors instead of proteasome inhibitor sufficiently blocked the p62/SQSTM1-mediated degradations of abnormal PrPs. Overexpression of p62/SQSTM1 did not alter the levels of light chain 3 (LC3) in the cells expressing various PrPs. However, more complexes of p62/SQSTM1 with LC3 were detected in the cells expressing the misfolded PrPs. These data imply that p62/SQSTM1 plays an important role in the homeostasis of abnormal PrPs via autophagy–lysosome-dependent way.