Autophosphorylation of polo-like kinase 4 and its role in centriole duplication.
Centrosome duplication occurs once every cell cycle in a strictly controlled manner. Polo-like kinase 4 (PLK4) is a key regulator of this process whose kinase activity is essential for centriole duplication. Here, we show that PLK4 autophosphorylation of serine S305 is a consequence of kinase activation and enables the active fraction to be identified in the cell. Active PLK4 is detectable on the replicating mother centriole in G1/S, with the proportion of active kinase increasing through interphase to reach a maximum in mitosis. Activation of PLK4 at the replicating daughter centriole is delayed until G2, but a level equivalent to the replicating mother centriole is achieved in M phase. Active PLK4 is regulated by the proteasome, because either proteasome inhibition or mutation of the degron motif of PLK4 results in the accumulation of S305-phosphorylated PLK4. Autophosphorylation probably plays a role in the process of centriole duplication, because mimicking S305 phosphorylation enhances the ability of overexpressed PLK4 to induce centriole amplification. Importantly, we show that S305-phosphorylated PLK4 is specifically sequestered at the centrosome contrary to the nonphosphorylated form. These data suggest that PLK4 activity is restricted to the centrosome to prevent aberrant centriole assembly and sustained kinase activity is required for centriole duplication.
Sillibourne
James E
JE
Institut Curie, Centre de Recherche/Unité Mixte de Recherche 144 du Centre Nationale de la Recherche Scientifique, 75248 Paris Cedex 05, France.
Tack
Frederik
F
Vloemans
Nele
N
Boeckx
An
A
Thambirajah
Sathiesan
S
Bonnet
Pascal
P
Ramaekers
Frans C S
FC
Bornens
Michel
M
Grand-Perret
Thierry
T
D000595:Amino Acid Sequence; D000818:Animals; D002453:Cell Cycle / Q000502:physiology*; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism; D002460:Cell Line; D002502:Centrioles / Q000378:metabolism*; D018385:Centrosome / Q000378:metabolism; D006801:Humans; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010766:Phosphorylation; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012694:Serine / Q000378:metabolism
D018797:Cell Cycle Proteins; D034741:RNA, Small Interfering; D011993:Recombinant Fusion Proteins; D012694:Serine; C490219:PLK4 protein, human; D017346:Protein Serine-Threonine Kinases; D046988:Proteasome Endopeptidase Complex