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PMID:19131964

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Citation

Martins, T, Maia, AF, Steffensen, S and Sunkel, CE (2009) Sgt1, a co-chaperone of Hsp90 stabilizes Polo and is required for centrosome organization. EMBO J. 28:234-47

Abstract

Sgt1 was described previously in yeast and humans to be a Hsp90 co-chaperone and required for kinetochore assembly. We have identified a mutant allele of Sgt1 in Drosophila and characterized its function. Mutations in sgt1 do not affect overall kinetochore assembly or spindle assembly checkpoint. sgt1 mutant cells enter less frequently into mitosis and arrest in a prometaphase-like state. Mutations in sgt1 severely compromise the organization and function of the mitotic apparatus. In these cells, centrioles replicate but centrosomes fail to mature, and pericentriolar material components do not localize normally resulting in highly abnormal spindles. Interestingly, a similar phenotype was described previously in Hsp90 mutant cells and correlated with a decrease in Polo protein levels. In sgt1 mutant neuroblasts, we also observe a decrease in overall levels of Polo. Overexpression of the kinase results in a substantial rescue of the centrosome defects; most cells form normal bipolar spindles and progress through mitosis normally. Taken together, these findings suggest that Sgt1 is involved in the stabilization of Polo allowing normal centrosome maturation, entry and progression though mitosis.

Links

PubMed PMC2637337 Online version:10.1038/emboj.2008.283

Keywords

Alleles; Amino Acid Sequence; Animals; Cell Survival; Centrioles/metabolism; Centrosome/enzymology; Drosophila Proteins/chemistry; Drosophila Proteins/metabolism; Drosophila melanogaster/cytology; Drosophila melanogaster/enzymology; Enzyme Stability; HSP90 Heat-Shock Proteins/metabolism; Kinetochores/metabolism; Mitosis; Mitotic Spindle Apparatus/metabolism; Molecular Chaperones/chemistry; Molecular Chaperones/metabolism; Molecular Sequence Data; Mutation/genetics; Neurons/cytology; Neurons/enzymology; Phenotype; Protein Transport; Protein-Serine-Threonine Kinases/metabolism; Subcellular Fractions/metabolism

Significance

Annotations

Gene product Qualifier GO Term Evidence Code with/from Aspect Extension Notes Status

DROME:Q2XYI8

located_in

GO:0005813: centrosome

ECO:0000314: direct assay evidence used in manual assertion

C

Seeded From UniProt

complete

DROME:Q2XYI8

located_in

GO:0000776: kinetochore

ECO:0000314: direct assay evidence used in manual assertion

C

Seeded From UniProt

complete

DROME:Q2XYI8

located_in

GO:0032154: cleavage furrow

ECO:0000314: direct assay evidence used in manual assertion

C

Seeded From UniProt

complete

DROME:Q2XYI8

involved_in

GO:0050821: protein stabilization

ECO:0000315: mutant phenotype evidence used in manual assertion

P

Seeded From UniProt

complete

DROME:Q2XYI8

involved_in

GO:0007098: centrosome cycle

ECO:0000315: mutant phenotype evidence used in manual assertion

P

Seeded From UniProt

complete

DROME:Q8SY87

located_in

GO:0005813: centrosome

ECO:0000314: direct assay evidence used in manual assertion

C

Seeded From UniProt

complete

DROME:Q8SY87

located_in

GO:0000776: kinetochore

ECO:0000314: direct assay evidence used in manual assertion

C

Seeded From UniProt

complete

DROME:Q8SY87

located_in

GO:0032154: cleavage furrow

ECO:0000314: direct assay evidence used in manual assertion

C

Seeded From UniProt

complete

DROME:Q8SY87

involved_in

GO:0050821: protein stabilization

ECO:0000315: mutant phenotype evidence used in manual assertion

P

Seeded From UniProt

complete

DROME:Q8SY87

involved_in

GO:0007098: centrosome cycle

ECO:0000315: mutant phenotype evidence used in manual assertion

P

Seeded From UniProt

complete

DROME:Q9VHT3

located_in

GO:0005813: centrosome

ECO:0000314: direct assay evidence used in manual assertion

C

Seeded From UniProt

complete

DROME:Q9VHT3

located_in

GO:0000776: kinetochore

ECO:0000314: direct assay evidence used in manual assertion

C

Seeded From UniProt

complete

DROME:Q9VHT3

located_in

GO:0032154: cleavage furrow

ECO:0000314: direct assay evidence used in manual assertion

C

Seeded From UniProt

complete

DROME:Q9VHT3

involved_in

GO:0050821: protein stabilization

ECO:0000315: mutant phenotype evidence used in manual assertion

P

Seeded From UniProt

complete

DROME:Q9VHT3

involved_in

GO:0007098: centrosome cycle

ECO:0000315: mutant phenotype evidence used in manual assertion

P

Seeded From UniProt

complete


See also

References

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