PKN Delays Mitotic Timing by Inhibition of Cdc25C: Possible Involvement of PKN in the Regulation of Cell Division

• Published in: Proceedings of the National Academy of Sciences - PNAS 2001-01, Vol.98 (1), p.125-129
• Main Authors: Misaki, Kazuyo, Mukai, Hideyuki, Yoshinaga, Chiho, Oishi, Kumiko, Isagawa, Takayuki, Takahashi, Mikiko, Ohsumi, Keita, Kishimoto, Takeo, Ono, Yoshitaka
• Format: Article
• Language: English
• Subjects: Amino acids; Animals; Antibodies; Biological Sciences; Cdc2 protein; CDC2 Protein Kinase - metabolism; Cdc25C protein; Cell cycle; Cell Cycle Proteins; Cell division; Cell Extracts; Cell Nucleus - metabolism; Cellular biology; Cyclin B - metabolism; Embryos; Enzyme Activation - drug effects; Female; Freshwater; Histones; Male; Microinjections; Mitosis; Mitosis - drug effects; Nuclear Proteins; Oocytes - cytology; Oocytes - enzymology; Oocytes - metabolism; Ova; Phosphorylation; Phosphorylation - drug effects; Physiological regulation; PKN protein; Protein Kinases - metabolism; Protein Serine-Threonine Kinases - metabolism; Protein Serine-Threonine Kinases - pharmacology; Protein Tyrosine Phosphatases - metabolism; Protein-Tyrosine Kinases - metabolism; Protein-Tyrosine Kinases - pharmacology; Proteins; ras-GRF1 - antagonists & inhibitors; ras-GRF1 - metabolism; Recombinant Fusion Proteins; Spermatozoa; Spermatozoa - cytology; Xenopus; Xenopus - embryology; Xenopus - metabolism; Xenopus Proteins
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.98.1.125

The role of PKN, a fatty acid- and Rho small GTPase-activated protein kinase, in cell-cycle regulation was analyzed. Microinjection of the active form of PKN into a Xenopus embryo caused cleavage arrest, whereas normal cell division proceeded in the control embryo microinjected with buffer or the inactive form of PKN. Exogenous addition of the active form of PKN delayed mitotic timing in Xenopus egg cycling extracts judging by morphology of sperm nuclei and Cdc2/cyclin B histone H1 kinase activity. The kinase-negative form of PKN did not affect the timing, suggesting that delayed mitotic timing depends on the kinase activity of PKN. The dephosphorylation of Tyr-15 of Cdc2 was also delayed in correlation with Cdc2/cyclin B histone H1 kinase activation in extracts containing active PKN. The Cdc25C activity for the dephosphorylation of Tyr-15 in Cdc2 was suppressed by pretreatment with the active form of PKN. Furthermore, PKN efficiently phosphorylated Cdc25C in vitro, indicating that PKN directly inhibits Cdc25C activity by phosphorylation. These results suggest that PKN plays a significant role in the control of mitotic timing by inhibition of Cdc25C.