title: Regulation of p27 degradation and S-phase progression by Ro52 RING finger protein.
abstract: Ubiquitin-mediated degradation of the cyclin-dependent kinase inhibitor p27 provides a powerful route for enforcing normal progression through the mammalian cell cycle. According to a current model, the ubiquitination of p27 during S-phase progression is mediated by SCF(Skp2) E3 ligase that captures Thr187-phosphorylated p27 by means of the F-box protein Skp2, which in turn couples the bound substrate via Skp1 to a catalytic core complex composed of Cul1 and the Rbx/Roc RING finger protein. Here we identify Skp2 as a component of an Skp1-cullin-F-box complex that is based on a Cul1-Ro52 RING finger B-box coiled-coil motif family protein catalytic core. Ro52-containing complexes display E3 ligase activity and promote the ubiquitination of Thr187-phosphorylated p27 in a RING-dependent manner in vitro. The knockdown of Ro52 expression in human cells with small interfering RNAs causes the accumulation of p27 and the failure of cells to enter S phase. Importantly, these effects are abrogated by the simultaneous removal of p27. Taken together, these data suggest a key role for Ro52 RING finger protein in the regulation of p27 degradation and S-phase progression in mammalian cells and provide evidence for the existence of a Cul1-based catalytic core that utilizes Ro52 RING protein to promote ubiquitination.
authors.affiliation: Institute of Cell Biology, ETH-Hönggerberg, 8093 Zurich, Switzerland. wilhelm.krek@cell.biol.ethz.ch.
authors.forename: Abdelmajid
authors.initials: A
authors.lastname: Sabile
authors.forename: Andrea Michael
authors.initials: AM
authors.lastname: Meyer
authors.forename: Christiane
authors.initials: C
authors.lastname: Wirbelauer
authors.forename: Daniel
authors.initials: D
authors.lastname: Hess
authors.forename: Ulrike
authors.initials: U
authors.lastname: Kogel
authors.forename: Martin
authors.initials: M
authors.lastname: Scheffner
authors.forename: Wilhelm
authors.initials: W
authors.lastname: Krek
mesh_terms: D020816:Amino Acid Motifs; D018797:Cell Cycle Proteins / Q000378:metabolism; D044842:Cullin Proteins / Q000378:metabolism; D050760:Cyclin-Dependent Kinase Inhibitor p27 / Q000378:metabolism*; D015536:Down-Regulation / Q000235:genetics; D006367:HeLa Cells; D006801:Humans; D010769:Phosphothreonine / Q000378:metabolism; D011485:Protein Binding; D011499:Protein Processing, Post-Translational; D012261:Ribonucleoproteins / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism*; D016196:S Phase; D025801:Ubiquitin / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism; D044844:beta-Transducin Repeat-Containing Proteins / Q000378:metabolism; D000099207:SS-A Antigen
chemical_list: D018797:Cell Cycle Proteins; D044842:Cullin Proteins; D050760:Cyclin-Dependent Kinase Inhibitor p27; D010769:Phosphothreonine; D012261:Ribonucleoproteins; D025801:Ubiquitin; D044767:Ubiquitin-Protein Ligases; D044844:beta-Transducin Repeat-Containing Proteins; D000099207:SS-A Antigen; C100318:Cullin 1; C471645:FBXW11 protein, human