title: The deubiquitinating protein USP24 interacts with DDB2 and regulates DDB2 stability.
abstract: Damage-specific DNA-binding protein 2 (DDB2) was first isolated as a subunit of the UV-DDB heterodimeric complex that is involved in DNA damage recognition in the nucleotide excision repair pathway (NER). DDB2 is required for efficient repair of CPDs in chromatin and is a component of the CRL4 (DDB2)  E3 ligase that targets XPC, histones and DDB2 itself for ubiquitination. In this study, a yeast two-hybrid screening of a human cDNA library was performed to identify potential DDB2 cellular partners. We identified a deubiquitinating enzyme, USP24, as a likely DDB2-interacting partner. Interaction between DDB2 and USP24 was confirmed by co-precipitation. Importantly, knockdown of USP24 in two human cell lines decreased the steady-state levels of DDB2, indicating that USP24-mediated DDB2 deubiquitination prevents DDB2 degradation. In addition, we demonstrated that USP24 can cleave an ubiquitinated form of DDB2 in vitro. Taken together, our results suggest that the ubiquitin-specific protease USP24 is a novel regulator of DDB2 stability.
authors.affiliation: Department of Biochemistry and Molecular Biology, Miller School of Medicine, University of Miami, Miami, FL USA.
authors.forename: Ling
authors.initials: L
authors.lastname: Zhang
authors.forename: Abigail
authors.initials: A
authors.lastname: Lubin
authors.forename: Hua
authors.initials: H
authors.lastname: Chen
authors.forename: Zhongyi
authors.initials: Z
authors.lastname: Sun
authors.forename: Feng
authors.initials: F
authors.lastname: Gong
mesh_terms: D004249:DNA Damage / Q000528:radiation effects; D004260:DNA Repair; D004268:DNA-Binding Proteins / Q000378:metabolism*; D010450:Endopeptidases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D057809:HEK293 Cells; D006367:HeLa Cells; D006801:Humans; D011485:Protein Binding; D055550:Protein Stability; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000378:metabolism; D020798:Two-Hybrid System Techniques; D043222:Ubiquitin Thiolesterase / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D064570:Ubiquitin-Specific Proteases; D054875:Ubiquitination; D014466:Ultraviolet Rays
chemical_list: C117669:DDB2 protein, human; D004268:DNA-Binding Proteins; D034741:RNA, Small Interfering; C513810:USP24 protein, human; D010450:Endopeptidases; D043222:Ubiquitin Thiolesterase; D064570:Ubiquitin-Specific Proteases