Identification of annexin A1 as a novel substrate for E6AP-mediated ubiquitylation.
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.
Shimoji
Tetsu
T
Department of Virology II, National Institute of Infectious Diseases, Shinjuku-ku, Tokyo, Japan.
Murakami
Kyoko
K
Sugiyama
Yuichi
Y
Matsuda
Mami
M
Inubushi
Sachiko
S
Nasu
Junichi
J
Shirakura
Masayuki
M
Suzuki
Tetsuro
T
Wakita
Takaji
T
Kishino
Tatsuya
T
Hotta
Hak
H
Miyamura
Tatsuo
T
Shoji
Ikuo
I
D000595:Amino Acid Sequence; D000818:Animals; D017305:Annexin A1 / Q000235:genetics / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism; D002460:Cell Line; D006801:Humans; D008969:Molecular Sequence Data; D011485:Protein Binding; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D025801:Ubiquitin / Q000378:metabolism*; D044767:Ubiquitin-Protein Ligases / Q000235:genetics / Q000378:metabolism*; D054875:Ubiquitination
D017305:Annexin A1; D034741:RNA, Small Interfering; D011993:Recombinant Fusion Proteins; D025801:Ubiquitin; C471639:UBE3A protein, human; D044767:Ubiquitin-Protein Ligases; D002118:Calcium