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Enhancement of ubiquitin conjugating activity promotes the clearance of aggregation‐prone mutant proteins in living cells
Author(s) -
Shang Fu,
Liu Zhenzhen,
Taylor Allen,
Zhang Xinyu,
Wu Mingxin,
Liu Yizhi,
Liang Jack J.N.
Publication year - 2013
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.27.1_supplement.553.19
Subject(s) - ubiquitin , intracellular , mutant , proteasome , microbiology and biotechnology , hela , chemistry , protein aggregation , hsp70 , protein degradation , biochemistry , biology , in vitro , heat shock protein , gene
Intracellular accumulation and aggregation of damaged proteins is a common cause of many age‐related degenerative diseases. In this study, we investigated whether enhancement of the ubiquitin‐proteasome pathway (UPP) promotes clearance of damaged proteins and prevents their intracellular accumulation and aggregation. A conformational‐defect T5P mutant γC‐crystallin (T5P‐γC ) was used as a model substrate. Similar to other damaged proteins, T5P‐γC was degraded by the UPP more rapidly than wild type γC‐crystallin (wt‐γC). Supplementation of C‐terminus of Hsp70 interacting protein (CHIP), or a ubiquitin conjugating enzyme (Ubc5) accelerates the degradation T5P‐γC. When expressed in living lens or HeLa cells, T5P‐γC formed intracellular aggregates whereas wt‐γC were evenly distributed. Co‐expression of CHIP or Ubc5 reduced the aggregation of T5P‐γC in cells. Cyclohexmide chase assay showed that CHIP and Ubc5 promoted the degradation of T5P‐γC, but not wt‐γC. Mutant CHIP with either a defective TPR‐domain or U‐box domain failed to reduce the protein level of T5P‐γC, suggesting molecular chaperones are involved in targeting the damaged proteins for degradation. Together, the data suggest that enhancing UPP activity can be an effective strategy to eliminate aggregation‐prone proteins.