S. Matsuzawa et Jc. Reed, Siah-1, SIP, and Ebi collaborate in a novel pathway for beta-catenin degradation linked to p53 responses, MOL CELL, 7(5), 2001, pp. 915-926
Destruction of beta -catenin is regulated through phosphorylation-dependent
interactions with the F box protein beta -TrCP. A novel pathway for beta -
catenin degradation was discovered involving mammalian homologs of Drosophi
la Sina (Siah), which bind ubiquitin-conjugating enzymes, and Ebi, an F box
protein that binds beta -catenin independent of the phosphorylation sites
recognized by beta -TrCP. A series of protein interactions were identified
in which Siah is physically linked to Ebi by association with a novel Sgt1
homolog SIP that binds Skp1, a central component of Skp1 -Cullin-F box comp
lexes. Expression of Siah is induced by p53, revealing a way of linking gen
otoxic injury to destruction of beta -catenin, thus reducing activity of Tc
f/LEF transcription factors and contributing to cell cycle arrest.