The Drosophila orthologue of xPlkk1 is not essential for Polo activation and is necessary for proper contractile ring formation.
Polo-like kinases (Plks) are essential for progression through mitosis. The activity of these kinases peak during M phase and this activation has been attributed to phosphorylation. Kinases capable of activating Plks in vitro have been previously identified both in mammalian cells and in Xenopus laevis oocytes (SLK and xPlkk1, respectively), although an in vivo correlation has not been clearly established. In order to study the regulation of Polo activity, we identified and cloned a Drosophila melanogaster kinase belonging to the ste20 ser/thr family that presents a close sequence homology with xPlkk1 and SLK. We termed this kinase dPlkk and showed that dPlkk associates with and phosphorylates Polo in vitro, resulting in the activation of the latter. On the other hand, when dPlkk is depleted from S2 cells, Polo activation does not seem to be impaired, suggesting that other kinases are involved in regulating Polo activity in vivo. Additionally, we found that a percentage of dPlkk-depleted cells fail to form a proper actin ring at the end of mitosis, leading to a failure in the assembly of the cleavage furrow and to the formation of binucleated cells. The detected accumulation of dPlkk in the contractile ring late in anaphase reinforces the idea that this kinase plays a role in cytokinesis.
Alves
Paulo S
PS
Centro de Biologia do Desenvolvimento, Instituto Gulbenkian de Ciência, 2781-901 Oeiras, Portugal.
Godinho
Susana A
SA
Tavares
Alvaro A
AA
D000199:Actins / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003599:Cytoskeleton / Q000502:physiology; D029721:Drosophila Proteins / Q000378:metabolism*; D004331:Drosophila melanogaster; D004789:Enzyme Activation; D019084:Fluorescent Antibody Technique, Indirect; D006657:Histones / Q000378:metabolism; D066298:In Vitro Techniques; D008969:Molecular Sequence Data; D004676:Myelin Basic Protein / Q000378:metabolism; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D029867:Xenopus Proteins
D000199:Actins; D029721:Drosophila Proteins; D006657:Histones; D004676:Myelin Basic Protein; D012333:RNA, Messenger; D029867:Xenopus Proteins; C115856:stk10-a protein, Xenopus; C072004:polo protein, Drosophila; D017346:Protein Serine-Threonine Kinases