title: Identification of Mitosis-Specific Phosphorylation in Mitotic Chromosome-Associated Proteins.
abstract: During mitosis, phosphorylation of chromosome-associated proteins is a key regulatory mechanism. Mass spectrometry has been successfully applied to determine the complete protein composition of mitotic chromosomes, but not to identify post-translational modifications. Here, we quantitatively compared the phosphoproteome of isolated mitotic chromosomes with that of chromosomes in nonsynchronized cells. We identified 4274 total phosphorylation sites and 350 mitosis-specific phosphorylation sites in mitotic chromosome-associated proteins. Significant mitosis-specific phosphorylation in centromere/kinetochore proteins was detected, although the chromosomal association of these proteins did not change throughout the cell cycle. This mitosis-specific phosphorylation might play a key role in regulation of mitosis. Further analysis revealed strong dependency of phosphorylation dynamics on kinase consensus patterns, thus linking the identified phosphorylation sites to known key mitotic kinases. Remarkably, chromosomal axial proteins such as non-SMC subunits of condensin, TopoIIα, and Kif4A, together with the chromosomal periphery protein Ki67 involved in the establishment of the mitotic chromosomal structure, demonstrated high phosphorylation during mitosis. These findings suggest a novel mechanism for regulation of chromosome restructuring in mitosis via protein phosphorylation. Our study generated a large quantitative database on protein phosphorylation in mitotic and nonmitotic chromosomes, thus providing insights into the dynamics of chromatin protein phosphorylation at mitosis onset.
authors: Center for Innovative and Translational Medicine Medical School, Kochi University Kohasu, Oko-cho, Nankoku, Kochi 783-8505, Japan.
authors: Shinya
authors: S
authors: Ohta
authors: Graduate School of Pharmaceutical Sciences, Kyoto University 46-29 Yoshidashimoadachi-cho, Sakyo-ku, Kyoto 606-8501, Japan.
authors: Michiko
authors: M
authors: Kimura
authors: Graduate School of Pharmaceutical Sciences, Kyoto University 46-29 Yoshidashimoadachi-cho, Sakyo-ku, Kyoto 606-8501, Japan.
authors: Shunsuke
authors: S
authors: Takagi
authors: Center for Innovative and Translational Medicine Medical School, Kochi University Kohasu, Oko-cho, Nankoku, Kochi 783-8505, Japan.
authors: Iyo
authors: I
authors: Toramoto
authors: Graduate School of Pharmaceutical Sciences, Kyoto University 46-29 Yoshidashimoadachi-cho, Sakyo-ku, Kyoto 606-8501, Japan.
authors: Yasushi
authors: Y
authors: Ishihama
mesh_terms: D001665:Binding Sites; D002460:Cell Line; D002868:Chromosomal Proteins, Non-Histone / Q000378:metabolism*; D022004:Chromosome Structures; D006801:Humans; D008938:Mitosis; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism
chemical_list: D002868:Chromosomal Proteins, Non-Histone; D011494:Protein Kinases
keywords: chromatin; chromosome; mitosis; phosphorylation