TY - JOUR
T1 - Isoform- and cell cycle-dependent substrate degradation by the Fbw7 ubiquitin ligase
AU - Grim, Jonathan E.
AU - Gustafson, Michael P.
AU - Hirata, Roli K.
AU - Hagar, Amanda C.
AU - Swanger, Jherek
AU - Welcker, Markus
AU - Hwang, Harry C.
AU - Ericsson, Johan
AU - Russell, David W.
AU - Clurman, Bruce E.
PY - 2008/6/16
Y1 - 2008/6/16
N2 - The SCFFBW7 ubiquitin ligase degrades proteins involved in cell division, growth, and differentiation and is commonly mutated in cancers. The Fbw7 locus encodes three protein isoforms that occupy distinct subcellular localizations, suggesting that each has unique functions. We used gene targeting to create isoform-specific Fbw7-null mutations in human cells and found that the nucleoplasmic Fbw7 α isoform accounts for almost all Fbw7 activity toward cyclin E, c-Myc, and sterol regulatory element binding protein 1. Cyclin E sensitivity to Fbw7 varies during the cell cycle, and this correlates with changes in cyclin E-cyclin-dependent kinase 2 (CDK2)-specific activity, cyclin E autophosphorylation, and CDK2 inhibitory phosphorylation. These data suggest that oscillations in cyclin E-CDK2-specific activity during the cell cycle regulate the timing of cyclin E degradation. Moreover, they highlight the utility of adeno-associated virus-mediated gene targeting in functional analyses of complex loci.
AB - The SCFFBW7 ubiquitin ligase degrades proteins involved in cell division, growth, and differentiation and is commonly mutated in cancers. The Fbw7 locus encodes three protein isoforms that occupy distinct subcellular localizations, suggesting that each has unique functions. We used gene targeting to create isoform-specific Fbw7-null mutations in human cells and found that the nucleoplasmic Fbw7 α isoform accounts for almost all Fbw7 activity toward cyclin E, c-Myc, and sterol regulatory element binding protein 1. Cyclin E sensitivity to Fbw7 varies during the cell cycle, and this correlates with changes in cyclin E-cyclin-dependent kinase 2 (CDK2)-specific activity, cyclin E autophosphorylation, and CDK2 inhibitory phosphorylation. These data suggest that oscillations in cyclin E-CDK2-specific activity during the cell cycle regulate the timing of cyclin E degradation. Moreover, they highlight the utility of adeno-associated virus-mediated gene targeting in functional analyses of complex loci.
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U2 - 10.1083/jcb.200802076
DO - 10.1083/jcb.200802076
M3 - Article
C2 - 18559665
AN - SCOPUS:45349091765
SN - 0021-9525
VL - 181
SP - 913
EP - 920
JO - Journal of Cell Biology
JF - Journal of Cell Biology
IS - 6
ER -