SCF(Cyclin F) controls centrosome homeostasis and mitotic fidelity through CP110 degradation.
Generally, F-box proteins are the substrate recognition subunits of SCF (Skp1-Cul1-F-box protein) ubiquitin ligase complexes, which mediate the timely proteolysis of important eukaryotic regulatory proteins. Mammalian genomes encode roughly 70 F-box proteins, but only a handful have established functions. The F-box protein family obtained its name from Cyclin F (also called Fbxo1), in which the F-box motif (the approximately 40-amino-acid domain required for binding to Skp1) was first described. Cyclin F, which is encoded by an essential gene, also contains a cyclin box domain, but in contrast to most cyclins, it does not bind or activate any cyclin-dependent kinases (CDKs). However, like other cyclins, Cyclin F oscillates during the cell cycle, with protein levels peaking in G2. Despite its essential nature and status as the founding member of the F-box protein family, Cyclin F remains an orphan protein, whose functions are unknown. Starting from an unbiased screen, we identified CP110, a protein that is essential for centrosome duplication, as an interactor and substrate of Cyclin F. Using a mode of substrate binding distinct from other F-box protein-substrate pairs, CP110 and Cyclin F physically associate on the centrioles during the G2 phase of the cell cycle, and CP110 is ubiquitylated by the SCF(Cyclin F) ubiquitin ligase complex, leading to its degradation. siRNA-mediated depletion of Cyclin F in G2 induces centrosomal and mitotic abnormalities, such as multipolar spindles and asymmetric, bipolar spindles with lagging chromosomes. These phenotypes were reverted by co-silencing CP110 and were recapitulated by expressing a stable mutant of CP110 that cannot bind Cyclin F. Finally, expression of a stable CP110 mutant in cultured cells also promotes the formation of micronuclei, a hallmark of chromosome instability. We propose that SCF(Cyclin F)-mediated degradation of CP110 is required for the fidelity of mitosis and genome integrity.
D'Angiolella
Vincenzo
V
Department of Pathology, NYU Cancer Institute, New York University School of Medicine, 522 First Avenue, SRB 1107, New York, New York 10016, USA.
Donato
Valerio
V
Vijayakumar
Sangeetha
S
Saraf
Anita
A
Florens
Laurence
L
Washburn
Michael P
MP
Dynlacht
Brian
B
Pagano
Michele
M
D000818:Animals; D018797:Cell Cycle Proteins / Q000378:metabolism*; D002460:Cell Line; D045744:Cell Line, Tumor; D002502:Centrioles / Q000378:metabolism; D018385:Centrosome / Q000737:chemistry / Q000378:metabolism*; D016213:Cyclins / Q000737:chemistry / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D016195:G2 Phase; D006706:Homeostasis; D006801:Humans; D051379:Mice; D008869:Microtubule-Associated Proteins / Q000378:metabolism*; D008938:Mitosis; D046912:Multiprotein Complexes / Q000378:metabolism; D010641:Phenotype; D010750:Phosphoproteins / Q000378:metabolism*; D011485:Protein Binding; D044843:SKP Cullin F-Box Protein Ligases / Q000378:metabolism; D013379:Substrate Specificity; D054875:Ubiquitination
C503669:CCNF protein, human; C467559:CCP110 protein, human; C503670:Ccnf protein, mouse; D018797:Cell Cycle Proteins; D016213:Cyclins; D008869:Microtubule-Associated Proteins; D046912:Multiprotein Complexes; D010750:Phosphoproteins; D044843:SKP Cullin F-Box Protein Ligases