title: Identification of TRIM22 as a RING finger E3 ubiquitin ligase.
abstract: TRIM22, a member of the TRIM family proteins which contain RING finger, B-box, and coiled-coil domains, has been reported as a transcriptional regulator and involved in various cellular processes. In this study, the E3 ubiquitin ligase activity, a novel property of TRIM22, was demonstrated. It was found that TRIM22 underwent self-ubiquitylation in vitro in combination with the E2 enzyme UbcH5B and the ubiquitylation was dependent on its RING finger domain. Further evidences showed that TRIM22 could also be self-ubiquitylated in vivo. Importantly, TRIM22 was conjugated with poly-ubiquitin chains and stabilized by the proteasome inhibitor in 293T cells, suggesting that TRIM22 targeted itself for proteasomal degradation through the poly-ubiquitylation. We also found that TRIM22 was located in the nucleus, indicating that TRIM22 might function as a nuclear E3 ubiquitin ligase.
authors.affiliation: Institute for Immunobiology, Department of Immunology, Shanghai Medical College of Fudan University, 138 Yi Xue Yuan Road, Shanghai 200032, PR China.
authors.forename: Zhijian
authors.initials: Z
authors.lastname: Duan
authors.forename: Bo
authors.initials: B
authors.lastname: Gao
authors.forename: Wei
authors.initials: W
authors.lastname: Xu
authors.forename: Sidong
authors.initials: S
authors.lastname: Xiong
mesh_terms: D002460:Cell Line; D002467:Cell Nucleus / Q000201:enzymology*; D006801:Humans; D015778:Minor Histocompatibility Antigens; D054829:RING Finger Domains; D012097:Repressor Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D000070584:Tripartite Motif Proteins; D044767:Ubiquitin-Protein Ligases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D054875:Ubiquitination
chemical_list: D015778:Minor Histocompatibility Antigens; D012097:Repressor Proteins; C094314:TRIM22 protein, human; D000070584:Tripartite Motif Proteins; D044767:Ubiquitin-Protein Ligases