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Dissection of ubiquitinated protein degradation by basal autophagy
Author(s) -
Takayama Kaori,
Matsuura Akira,
Itakura Eisuke
Publication year - 2017
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1002/1873-3468.12641
Subject(s) - autophagy , ubiquitin , microbiology and biotechnology , basal (medicine) , ubiquitin protein ligases , biology , protein aggregation , proteolysis , ubiquitin conjugating enzyme , protein degradation , biochemistry , ubiquitin ligase , enzyme , endocrinology , apoptosis , gene , insulin
Basal autophagy plays an essential role as a protein quality control system. Although it has been demonstrated that the loss of autophagy results in the accumulation of ubiquitin‐positive aggregates and the development of neurodegenerative diseases, the precise autophagy substrate(s) remain unclear. Here, we determined whether ubiquitinated proteins are direct substrates for basal autophagy using a fluorescent ratiometric probe for ubiquitin. We show that the degradation of polyubiquitinated proteins is not dependent on basal autophagy. Although ubiquitin‐positive aggregates are observed in autophagy knockout cultured cells, the aggregates consist of soluble and mobile polyubiquitinated proteins, which are trapped by p62 without an increase in the total amount of ubiquitinated proteins. These results suggest that ubiquitinated proteins are not major targets for basal autophagy.