Mitotic Phosphorylation of the Peripheral Golgi Protein Nir2 by Cdk1 Provides a Docking Mechanism for Plk1 and Affects Cytokinesis Completion

Abstract

The rearrangement of the Golgi apparatus during mitosis is regulated by several protein kinases, including Cdk1 and Plk1. Several peripheral Golgi proteins that dissociate from the Golgi during mitosis are implicated in regulation of cytokinesis or chromosome segregation, thereby coordinating mitotic and cytokinetic events to Golgi rearrangement. Here we show that, at the onset of mitosis, Cdk1 phosphorylates the peripheral Golgi protein Nir2 at multiple sites; of these, S382 is the most prominent. Phosphorylation of Nir2 by Cdk1 facilitates its dissociation from the Golgi apparatus, and phospho-Nir2(pS382) is localized in the cleavage furrow and midbody during cytokinesis. Mitotic phosphorylation of Nir2 is required for docking of the phospho-Ser/Thr binding module, the Polo box domain of Plk1, and overexpression of a Nir2 mutant, which fails to interact with Plk1, affects the completion of cytokinesis. These results demonstrate a mechanism for coordinating mitotic and cytokinetic events with Golgi rearrangement during cell division.

Getting in and out of mitosis with Polo-like kinase-1

“…In line with these observations, depletion of MKlp1/CHO1 or MKlp2 or deletion of the Plk1-phosphorylation sites in MKlp1/Cho1 or MKlp2 disrupts Plk1 localization to the central spindle (Lee et al, 1995;Adams et al, 1998;Neef et al, 2003;Liu et al, 2004). Similar observations were made with the Golgi-associated protein Nir2 (Litvak et al, 2004). Plk1 was shown to depend on phosphorylated Nir2 for decent localization to the central spindle.…”

“…However, whereas MKlp1/CHO1 and MKlp2 require Plk1-phosphorylation, Nir2 requires Cdk1-phosphorylation for Plk1-binding. Furthermore, both Nir2-depletion or removal of the Cdk1-phosphorylation site in Nir2 resulted in failure to properly localize Plk1 to the midzone (Litvak et al, 2004). In addition, Plk1 was shown to phosphorylate NudC, a dynein-associated nuclear movement protein that plays a role in cytokinesis (Zhou et al, 2003).…”

“…Both Plk1 and Plk3 were suggested to regulate partitioning of Golgi-stacks during cell division (Sutterlin et al, 2001;Ruan et al, 2004). In addition, Plk1 was shown to interact and phosphorylate the Golgi-associated proteins Grasp65 and Nir2 (Lin et al, 2000;Litvak et al, 2004) and Plk3 colocalizes to Golgimarkers Giantin. Finally, overexpression of Plk3 results in premature Golgi-partitioning (Ruan et al, 2004).…”

“…Clearly, interference with Plk1-substrates MKlp1, MKlp2, NudC or Nir2, as well as Plk1 itself results in defects in the final stages of cytokinesis rather then disturbing the whole cytokinesis process (Seong et al, 2002;Neef et al, 2003;Zhou et al, 2003;Litvak et al, 2004;Matuliene and Kuriyama, 2004;van Vugt et al, 2004b). In addition, removal of the Plk1 phosphorylation sites in MKlp1/CHO1 or MKlp2 does not block furrow ingression, but prevents abscission, Figure 4 Mitotic exit.…”

Monitoring the Cell Cycle by Multi-Kinase-Dependent Regulation of Swe1/Wee1 in Budding Yeast

“…Analogous interactions between the polo-box domain of mammalian polo-like kinase Plk1 and its phosphorylated substrates by Cdk1 have been previously reported. [26][27][28][29][30] Thus, concerted action of Cdc28/Cdk1 and Cdc5/Polo on their common substrates appears to be an evolutionarily conserved mechanism that is designed to effectively bring about various mitotic events.…”