Cell division cycle 6, a mitotic substrate of polo-like kinase 1, regulates chromosomal segregation mediated by cyclin-dependent kinase 1 and separase

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 107; no. 46; pp. 19742 - 19747
• Main Authors: Yim, Hyungshin, Erikson, Raymond L.
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 16.11.2010; National Acad Sciences
• Subjects: Antibodies; Binding sites; Biological Sciences; CDC2 Protein Kinase - metabolism; Cell cycle; Cell Cycle Proteins - chemistry; Cell Cycle Proteins - metabolism; Cell division; Cell separation; Chromosome Segregation; Cyclin A - metabolism; Cyclin B1 - metabolism; Cyclin-dependent kinases; Cyclins; Deoxyribonucleic acid; DNA; DNA Replication; Endopeptidases - metabolism; Enzyme Activation; Gene expression; Gene expression regulation; Giant Cells - cytology; Giant Cells - metabolism; HEK293 Cells; HeLa Cells; Humans; Immunohistochemistry; Interphase; Mitosis; Models, Biological; Mutant Proteins - metabolism; Nuclear Proteins - deficiency; Nuclear Proteins - metabolism; Phosphorylation; Phosphothreonine - metabolism; Polo-Like Kinase 1; Protein Binding; Protein Serine-Threonine Kinases - chemistry; Protein Serine-Threonine Kinases - deficiency; Protein Serine-Threonine Kinases - metabolism; Protein Structure, Tertiary; Proto-Oncogene Proteins - chemistry; Proto-Oncogene Proteins - deficiency; Proto-Oncogene Proteins - metabolism; Separase; Substrate Specificity
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.1013557107

Defining the links between cell division and DNA replication is essential for understanding normal cell cycle progression and tumorigenesis. In this report we explore the effect of phosphorylation of cell division cycle 6 (Cdc6), a DNA replication initiation factor, by polo-like kinase 1 (Plk1) on the regulation of chromosomal segregation. In mitosis, the phosphorylation of Cdc6 was highly increased, in correlation with the level of Plk1, and conversely, Cdc6 is hypophosphorylated in Plk1-depleted cells, although cyclin A- and cyclin B1-dependent kinases are active. Binding between Cdc6 and Plk1 occurs through the polo-box domain of Plk1, and Cdc6 is phosphorylated by Plk1 on T37. Immunohistochemistry studies reveal that Cdc6 and Plk1 colocalize to the central spindle in anaphase. Expression of T37V mutant of Cdc6 (Cdc6-TV) induces binucleated cells and incompletely separated nuclei. Wild-type Cdc6 but not Cdc6-TV binds cyclin-dependent kinase 1 (Cdk1). Expression of wild-type Plk1 but not kinase-defective mutant promotes the binding of Cdc6 to Cdk1. Cells expressing wild-type Cdc6 display lower Cdk1 activity and higher separase activity than cells expressing Cdc6-TV. These results suggest that Plk1-mediated phosphorylation of Cdc6 promotes the interaction of Cdc6 and Cdk1, leading to the attenuation of Cdk1 activity, release of separase, and subsequent anaphase progression.