REGULAR ARTICLES

Cell Research (2003); 13(4):275-283

Mitosin/CENP-F is a conserved kinetochore protein subjected to cytoplasmic dynein-mediated poleward transport

Zhen Ye YANG, Jing GUO, Ning LI, Min QIAN, Sheng Nian WANG, Xue Liang ZHU^*

Received April-24-2003 Revised June-24-2003 Accepted June-27-2003

Correspondence: Prof. Xue Liang ZHU Institute of Biochemistry and Cell Biology, 320 Yueyang Road, Shanghai 200031, China 0086-21-54921406 (phone) 0086-21-54921011 (fax) xlzhu@sibs.ac.cn

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Mitosin/CENP-F is a human nuclear protein transiently associated with the outer kinetochore plate in M phase and is involved in M phase progression. LEK1 and CMF1, which are its murine and chicken orthologs, however, are implicated in muscle differentiation and reportedly not distributed at kinetochores. We therefore conducted several assays to clarify this issue. The typical centromere staining patterns were observed in mitotic cells from both human primary culture and murine, canine, and mink cell lines. A C-terminal portion of LEK1 also conferred centromere localization. Our analysis further suggests conserved kinetochore localization of mammalian mitosin orthologs. Moreover, mitosin was associated preferentially with kinetochores of unaligned chromosomes. It was also constantly transported from kinetochores to spindle poles by cytoplasmic dynein. These properties resemble those of other kinetochore proteins important for the spindle checkpoint, thus implying a role of mitosin in this checkpoint. Therefore, mitosin family may serve as multifunctional proteins involved in both mitosis and differentiation.

Key words: mitosin, LEK1, CENP-F, kinetochore.