Phosphorylation of the Mitotic Regulator Protein Hec1 by Nek2 Kinase Is Essential for Faithful Chromosome Segregation

Hec1 (highly expressed incancer) plays essential roles in chromosome segregation by interacting through its coiled-coil domains with several proteins that modulate the G2/M phase. Hec1 localizes to kinetochores, and its inactivation either by genetic deletion or antibody neutralization leads to seve...

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Bibliographic Details
Published in:The Journal of biological chemistry 2002-12, Vol.277 (51), p.49408-49416
Main Authors: Chen, Yumay, Riley, Daniel J., Zheng, Lei, Chen, Phang-Lang, Lee, Wen-Hwa
Format: Article
Language:English
Subjects:
Alanine - chemistry
Amino Acid Sequence
Amino Acids - chemistry
Blotting, Western
Cell Cycle
Chromosome Segregation
Cytoskeletal Proteins
DNA, Complementary - metabolism
Escherichia coli - metabolism
G2 Phase
Genotype
Glutathione Transferase - metabolism
Humans
Mitosis
Molecular Sequence Data
Mutation
NIMA-Related Kinases
Nuclear Proteins - metabolism
Phosphorylation
Precipitin Tests
Protein Binding
Protein-Serine-Threonine Kinases - metabolism
Recombinant Fusion Proteins - metabolism
Saccharomyces cerevisiae - genetics
Saccharomyces cerevisiae Proteins - metabolism
Serine - chemistry
Serine - metabolism
Temperature
Time Factors
Tumor Cells, Cultured
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Summary:Hec1 (highly expressed incancer) plays essential roles in chromosome segregation by interacting through its coiled-coil domains with several proteins that modulate the G2/M phase. Hec1 localizes to kinetochores, and its inactivation either by genetic deletion or antibody neutralization leads to severe and lethal chromosomal segregation errors, indicating that Hec1 plays a critical role in chromosome segregation. The mechanisms by which Hec1 is regulated, however, are not known. Here we show that human Hec1 is a serine phosphoprotein and that it binds specifically to the mitotic regulatory kinase Nek2 during G2/M. Nek2 phosphorylates Hec1 on serine residue 165, both in vitro and in vivo. Yeast cells are viable without scNek2/Kin3, a close structural homolog of Nek2 that binds to both human and yeast Hec1. When the same yeasts carry an scNek2/Kin3 (D55G) or Nek2 (E38G) mutation to mimic a similar temperature-sensitive nima mutation inAspergillus, their growth is arrested at the nonpermissive temperature, because the scNek2/Kin3 (D55G) mutant binds to Hec1 but fails to phosphorylate it. Whereas wild-type human Hec1 rescues lethality resulting from deletion of Hec1 in Saccharomyces cerevesiae, a human Hec1 mutant or yeast Hec1 mutant changing Ser165 to Ala or yeast Hec1 mutant changing Ser201 to Ala does not. Mutations changing the same Ser residues to Glu, to mimic the negative charge created by phosphorylation, partially rescue lethality but result in a high incidence of errors in chromosomal segregation. These results suggest that cell cycle-regulated serine phosphorylation of Hec1 by Nek2 is essential for faithful chromosome segregation.
ISSN:0021-9258
1083-351X
DOI:10.1074/jbc.M207069200