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© The Rockefeller University Press,
0021-9525/2000//837 $5.00
The Journal of Cell Biology, Volume 151, Number 4,
, 2000 837-846
Original Article |
The Centrosomal Protein C-Nap1 Is Required for Cell Cycle–Regulated Centrosome Cohesion
Duplicating centrosomes are paired during interphase, but are separated at the onset of mitosis. Although the mechanisms controlling centrosome cohesion and separation are important for centrosome function throughout the cell cycle, they remain poorly understood. Recently, we have proposed that C-Nap1, a novel centrosomal protein, is part of a structure linking parental centrioles in a cell cycle–regulated manner. To test this model, we have performed a detailed structure–function analysis on C-Nap1. We demonstrate that antibody-mediated interference with C-Nap1 function causes centrosome splitting, regardless of the cell cycle phase. Splitting occurs between parental centrioles and is not dependent on the presence of an intact microtubule or microfilament network. Centrosome splitting can also be induced by overexpression of truncated C-Nap1 mutants, but not full-length protein. Antibodies raised against different domains of C-Nap1 prove that this protein dissociates from spindle poles during mitosis, but reaccumulates at centrosomes at the end of cell division. Use of the same antibodies in immunoelectron microscopy shows that C-Nap1 is confined to the proximal end domains of centrioles, indicating that a putative linker structure must contain additional proteins. We conclude that C-Nap1 is a key component of a dynamic, cell cycle–regulated structure that mediates centriole–centriole cohesion.
Key Words: centrosome separation • mitotic spindle • centriole • C-Nap1 • Nek2
© 2000 The Rockefeller University Press
T. Mayor's present address is Department of Cell Biology, Max-Planck-Institute for Biochemistry, D-82152 Martinsried, Germany.K. Tanaka's present address is School of Biological Science, University of Manchester, Manchester M13 9PT, United Kingdom.
A.M. Fry's present address is Department of Biochemistry, University of Leicester, Leicester LE1 7 RH, United Kingdom.
Abbreviations used in this paper: aa, amino acid; BDM, 2,3-butanedione monoxime; MF, microfilament; MT, microtubule; PCM, pericentriolar material.
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