Polo-like kinase 1 facilitates chromosome alignment during prometaphase through BubR1.
Plk1, an evolutionarily conserved M phase kinase, associates with not only spindle poles but also kinetochores during prometaphase. However, the role of Plk1 at kinetochores has been poorly understood. Here we show that BubR1 mediates the action of Plk1 at kinetochores for proper chromosome alignment. Our results show that BubR1 colocalizes with Plk1 at kinetochores of unaligned chromosomes and physically interacts with Plk1 in prometaphase cells. Down-regulation of Plk1 by small interfering RNA abolished the mobility-shifted, hyperphosphorylated form of BubR1 in the prometaphase-arrested cells. In addition, BubR1 was phosphorylated by Plk1 in vitro at two Plk1 consensus sites in the kinase domain of BubR1. The add-back of either wild-type BubR1 or BubR1 2E, in which the two Plk1 phosphorylation sites were replaced by glutamic acids, but not that of BubR1 2A, an unphosphorylatable mutant, rescued the chromosome alignment defects in BubR1-deficient cells. Moreover, when both Plk1 and BubR1 were down-regulated, the add-back of BubR1 2E, but not that of wild-type BubR1, rescued the chromosome alignment defects. These results taken together suggest that Plk1 facilitates chromosome alignment during prometaphase through BubR1.
Matsumura
Shigeru
S
Department of Cell and Developmental Biology, Graduate School of Biostudies, Kyoto University, Kyoto 606-8502, Japan.
Toyoshima
Fumiko
F
Nishida
Eisuke
E
D019943:Amino Acid Substitution; D000818:Animals; D019556:COS Cells; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D002522:Chlorocebus aethiops; D002877:Chromosomes, Human / Q000378:metabolism*; D015536:Down-Regulation / Q000502:physiology; D006367:HeLa Cells; D006801:Humans; D018386:Kinetochores / Q000201:enzymology*; D008677:Metaphase / Q000502:physiology*; D020125:Mutation, Missense; D010766:Phosphorylation; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D017434:Protein Structure, Tertiary / Q000502:physiology; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D000097869:Polo-Like Kinase 1
D018797:Cell Cycle Proteins; D011494:Protein Kinases; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D000097869:Polo-Like Kinase 1; C584277:BUB1 protein, human; C090464:Bub1 spindle checkpoint protein