A Role for Plk1 Phosphorylation of NudC in Cytokinesis

Abstract

Polo-like kinase 1 (Plk1) plays essential roles at multiple events during cell division, yet little is known about its physiological substrates. In a cDNA phage display screen using Plk1 C-terminal affinity columns, we identified NudC (nuclear distribution gene C) as a Plk1 binding protein. Here, we characterize the interaction between Plk1 and NudC, show that Plk1 phosphorylates NudC at conserved S274 and S326 residues in vitro, and present evidence that NudC is also a substrate for Plk1 in vivo. Downregulation of NudC by RNA interference results in multiple mitotic defects, including multinucleation and cells arrested at the midbody stage, which are rescued by ectopic expression of wild-type NudC, but not by NudC with mutations in the Plk1 phosphorylation sites. These results suggest that Plk1 phosphorylation of NudC may influence cytokinesis.

NudC regulates actin dynamics and ciliogenesis by stabilizing cofilin 1

“…GST pull-down assays were performed as described previously [15]. To detect the association between NudC and cofilin 1, blots were probed with antibodies indicated in the text.…”

“…We and other groups have found that NudC plays crucial roles in diverse cellular processes, including cell division and neuronal migration, partially by modulating the dynein complex [13][14][15]. A growing body of evidence implies that NudC functions as a co-chaperone of Hsp90 to stabilize client proteins [16][17][18].…”

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

“…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). Clearly, multiple proteins are required to properly localize Plk1 to the central spindle.…”

“…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.…”

Protein kinases controlling the onset of mitosis

“…The many functions of Plk1 at mitosis [87] are well accounted for by the variety of substrates so far identified for this kinase. These consist of proteins involved with chromosome segregation, such as cohesin [88], microtubules dynamics [89] and nucleation [90] as well as cytokinesis [91]. In addition to the regulation of mechanistic aspects of mitosis, Plk1 contributes to set the timing of entry and transition through mitosis by phosphorylating APC/C subunits [92,93].…”