title: Localization of phosphorylated CK2alpha to the mitotic spindle requires the peptidyl-prolyl isomerase Pin1.
abstract: CK2 is a serine/threonine kinase with many substrates, largely unknown modes of regulation and essential roles in mitotic progression. CK2α, a catalytic subunit of CK2, is phosphorylated in mitosis, and here we examine the effect of phosphorylation on CK2α localization. Using phosphospecific antibodies, we show that CK2α localizes to the mitotic spindle in a phosphorylation-dependent manner. Mitotic spindle localization requires the unique C-terminus of CK2α, and involves a novel regulatory mechanism in which phosphorylation of CK2α facilitates binding to the peptidyl-prolyl isomerase Pin1, which is required for CK2α mitotic spindle localization. This could explain how the constitutive activity of CK2α might be targeted towards mitotic substrates. Furthermore, because Pin1 has many important spindle substrates, this might represent a general mechanism for localization of mitotic signalling proteins.
authors.affiliation: Department of Biochemistry, Schulich School of Medicine and Dentistry, University of Western Ontario, London ON N6A 5C1, Canada. litchfi@uwo.ca
authors.forename: Nicole A
authors.initials: NA
authors.lastname: St-Denis
authors.forename: Melanie L
authors.initials: ML
authors.lastname: Bailey
authors.forename: Erin L
authors.initials: EL
authors.lastname: Parker
authors.forename: Greg
authors.initials: G
authors.lastname: Vilk
authors.forename: David W
authors.initials: DW
authors.lastname: Litchfield
mesh_terms: D047390:Casein Kinase II / Q000378:metabolism*; D045744:Cell Line, Tumor; D006367:HeLa Cells; D006801:Humans; D007527:Isoenzymes; D008938:Mitosis / Q000502:physiology; D000072340:NIMA-Interacting Peptidylprolyl Isomerase; D019696:Peptidylprolyl Isomerase / Q000378:metabolism*; D010766:Phosphorylation; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D008941:Spindle Apparatus / Q000201:enzymology*
chemical_list: D007527:Isoenzymes; D000072340:NIMA-Interacting Peptidylprolyl Isomerase; D047390:Casein Kinase II; C000606846:PIN1 protein, human; D019696:Peptidylprolyl Isomerase