Identification of annexin A1 as a novel substrate for E6AP-mediated ubiquitylation

✍ Scribed by Tetsu Shimoji; Kyoko Murakami; Yuichi Sugiyama; Mami Matsuda; Sachiko Inubushi; Junichi Nasu; Masayuki Shirakura; Tetsuro Suzuki; Takaji Wakita; Tatsuya Kishino; Hak Hotta; Tatsuo Miyamura; Ikuo Shoji

• Publisher: John Wiley and Sons
• Year: 2009
• Tongue: English
• Weight: 443 KB
• Volume: 106
• Category: Article
• ISSN: 0730-2312
• DOI: 10.1002/jcb.22096

✦ Synopsis

Abstract

E6‐associated protein (E6AP) is a cellular ubiquitin protein ligase that mediates ubiquitylation and degradation of p53 in conjunction with the high‐risk human papillomavirus E6 proteins. However, the physiological functions of E6AP are poorly understood. To identify a novel biological function of E6AP, we screened for binding partners of E6AP using GST pull‐down and mass spectrometry. Here we identified annexin A1, a member of the annexin superfamily, as an E6AP‐binding protein. Ectopic expression of E6AP enhanced the degradation of annexin A1 in vivo. RNAi‐mediated downregulation of endogenous E6AP increased the levels of endogenous annexin A1 protein. E6AP interacted with annexin A1 and induced its ubiquitylation in a Ca^2+^‐dependent manner. GST pull‐down assay revealed that the annexin repeat domain III of annexin A1 is important for the E6AP binding. Taken together, our data suggest that annexin A1 is a novel substrate for E6AP‐mediated ubiquitylation. Our findings raise the possibility that E6AP may play a role in controlling the diverse functions of annexin A1 through the ubiquitin‐proteasome pathway. J. Cell. Biochem. 106: 1123–1135, 2009. © 2009 Wiley‐Liss, Inc.