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CSC-1: a subunit of the Aurora B kinase complex that binds to the survivin-like protein BIR-1 and the incenp-like protein ICP-1.

Romano A, Guse A, Krascenicova I, Schnabel H, Schnabel R, Glotzer M - J. Cell Biol. (2003)

Bottom Line: CSC-1 associates with ICP-1, BIR-1, and AIR-2 in vivo.ICP-1 dramatically stimulates AIR-2 kinase activity.This activity is not stimulated by CSC-1/BIR-1, suggesting that these two subunits function as targeting subunits for AIR-2 kinase.

View Article: PubMed Central - PubMed

Affiliation: Research Institute of Molecular Pathology, Dr. Bohrgasse 7, Vienna A-1030, Austria.

ABSTRACT
The Aurora B kinase complex is a critical regulator of chromosome segregation and cytokinesis. In Caenorhabditis elegans, AIR-2 (Aurora B) function requires ICP-1 (Incenp) and BIR-1 (Survivin). In various systems, Aurora B binds to orthologues of these proteins. Through genetic analysis, we have identified a new subunit of the Aurora B kinase complex, CSC-1. C. elegans embryos depleted of CSC-1, AIR-2, ICP-1, or BIR-1 have identical phenotypes. CSC-1, BIR-1, and ICP-1 are interdependent for their localization, and all are required for AIR-2 localization. In vitro, CSC-1 binds directly to BIR-1. The CSC-1/BIR-1 complex, but not the individual subunits, associates with ICP-1. CSC-1 associates with ICP-1, BIR-1, and AIR-2 in vivo. ICP-1 dramatically stimulates AIR-2 kinase activity. This activity is not stimulated by CSC-1/BIR-1, suggesting that these two subunits function as targeting subunits for AIR-2 kinase.

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CSC-1, BIR-1, and ICP-1 are interdependent for their localization. (A) The localization of CSC-1 and known members of the ABI complex to meiotic chromatin was assayed by indirect immunofluorescence in fertilized oocytes of the indicated genotype. Embryos were costained with an anti-tubulin antibody to control for antibody accessibility. (B) Depletion of CSC-1 and ICP-1 reduces BIR-1 accumulation. Embryo extracts from RNAi-treated worms were analyzed by immunoblotting with antibodies directed against the indicated proteins. Immunoblotting with anti–α-tubulin (DM1α) antibodies demonstrates equal protein loading. Control embryo extracts were prepared using an RNAi construct that does not cause a phenotype. Dilutions of the control extracts were run in parallel to allow the degree of depletion to be estimated.
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fig3: CSC-1, BIR-1, and ICP-1 are interdependent for their localization. (A) The localization of CSC-1 and known members of the ABI complex to meiotic chromatin was assayed by indirect immunofluorescence in fertilized oocytes of the indicated genotype. Embryos were costained with an anti-tubulin antibody to control for antibody accessibility. (B) Depletion of CSC-1 and ICP-1 reduces BIR-1 accumulation. Embryo extracts from RNAi-treated worms were analyzed by immunoblotting with antibodies directed against the indicated proteins. Immunoblotting with anti–α-tubulin (DM1α) antibodies demonstrates equal protein loading. Control embryo extracts were prepared using an RNAi construct that does not cause a phenotype. Dilutions of the control extracts were run in parallel to allow the degree of depletion to be estimated.

Mentions: To examine whether CSC-1 is required for the localization of other ABI complex members, RNAi was used to deplete embryos of CSC-1, and the localization of AIR-2, ICP-1, and BIR-1 to meiotic chromosomes was examined by immunofluorescence, as this is the first instance where these proteins are functionally required. All three proteins require CSC-1 to localize to meiotic chromatin (Fig. 3 A, second row), mitotic chromosomes, and the spindle midzone in meiosis and mitosis (unpublished data). To determine whether CSC-1 localization requires ABI complex members, embryos were depleted of AIR-2, ICP-1, and BIR-1 by RNAi, and the localization of CSC-1 was examined by immunofluorescence. CSC-1 localization is dependent on BIR-1 and ICP-1, but independent of AIR-2 (Fig. 3 A, third row). Furthermore, BIR-1 and ICP-1 are interdependent, but AIR-2 independent, for their proper localization (Fig. 3 A, fourth row; Speliotes et al., 2000; unpublished data). Thus, CSC-1, BIR-1, and ICP-1 are mutually interdependent, but AIR-2 independent, for their localization to chromosomes. AIR-2 requires CSC-1, BIR-1, and ICP-1 to localize to chromosomes.


CSC-1: a subunit of the Aurora B kinase complex that binds to the survivin-like protein BIR-1 and the incenp-like protein ICP-1.

Romano A, Guse A, Krascenicova I, Schnabel H, Schnabel R, Glotzer M - J. Cell Biol. (2003)

CSC-1, BIR-1, and ICP-1 are interdependent for their localization. (A) The localization of CSC-1 and known members of the ABI complex to meiotic chromatin was assayed by indirect immunofluorescence in fertilized oocytes of the indicated genotype. Embryos were costained with an anti-tubulin antibody to control for antibody accessibility. (B) Depletion of CSC-1 and ICP-1 reduces BIR-1 accumulation. Embryo extracts from RNAi-treated worms were analyzed by immunoblotting with antibodies directed against the indicated proteins. Immunoblotting with anti–α-tubulin (DM1α) antibodies demonstrates equal protein loading. Control embryo extracts were prepared using an RNAi construct that does not cause a phenotype. Dilutions of the control extracts were run in parallel to allow the degree of depletion to be estimated.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2172917&req=5

fig3: CSC-1, BIR-1, and ICP-1 are interdependent for their localization. (A) The localization of CSC-1 and known members of the ABI complex to meiotic chromatin was assayed by indirect immunofluorescence in fertilized oocytes of the indicated genotype. Embryos were costained with an anti-tubulin antibody to control for antibody accessibility. (B) Depletion of CSC-1 and ICP-1 reduces BIR-1 accumulation. Embryo extracts from RNAi-treated worms were analyzed by immunoblotting with antibodies directed against the indicated proteins. Immunoblotting with anti–α-tubulin (DM1α) antibodies demonstrates equal protein loading. Control embryo extracts were prepared using an RNAi construct that does not cause a phenotype. Dilutions of the control extracts were run in parallel to allow the degree of depletion to be estimated.
Mentions: To examine whether CSC-1 is required for the localization of other ABI complex members, RNAi was used to deplete embryos of CSC-1, and the localization of AIR-2, ICP-1, and BIR-1 to meiotic chromosomes was examined by immunofluorescence, as this is the first instance where these proteins are functionally required. All three proteins require CSC-1 to localize to meiotic chromatin (Fig. 3 A, second row), mitotic chromosomes, and the spindle midzone in meiosis and mitosis (unpublished data). To determine whether CSC-1 localization requires ABI complex members, embryos were depleted of AIR-2, ICP-1, and BIR-1 by RNAi, and the localization of CSC-1 was examined by immunofluorescence. CSC-1 localization is dependent on BIR-1 and ICP-1, but independent of AIR-2 (Fig. 3 A, third row). Furthermore, BIR-1 and ICP-1 are interdependent, but AIR-2 independent, for their proper localization (Fig. 3 A, fourth row; Speliotes et al., 2000; unpublished data). Thus, CSC-1, BIR-1, and ICP-1 are mutually interdependent, but AIR-2 independent, for their localization to chromosomes. AIR-2 requires CSC-1, BIR-1, and ICP-1 to localize to chromosomes.

Bottom Line: CSC-1 associates with ICP-1, BIR-1, and AIR-2 in vivo.ICP-1 dramatically stimulates AIR-2 kinase activity.This activity is not stimulated by CSC-1/BIR-1, suggesting that these two subunits function as targeting subunits for AIR-2 kinase.

View Article: PubMed Central - PubMed

Affiliation: Research Institute of Molecular Pathology, Dr. Bohrgasse 7, Vienna A-1030, Austria.

ABSTRACT
The Aurora B kinase complex is a critical regulator of chromosome segregation and cytokinesis. In Caenorhabditis elegans, AIR-2 (Aurora B) function requires ICP-1 (Incenp) and BIR-1 (Survivin). In various systems, Aurora B binds to orthologues of these proteins. Through genetic analysis, we have identified a new subunit of the Aurora B kinase complex, CSC-1. C. elegans embryos depleted of CSC-1, AIR-2, ICP-1, or BIR-1 have identical phenotypes. CSC-1, BIR-1, and ICP-1 are interdependent for their localization, and all are required for AIR-2 localization. In vitro, CSC-1 binds directly to BIR-1. The CSC-1/BIR-1 complex, but not the individual subunits, associates with ICP-1. CSC-1 associates with ICP-1, BIR-1, and AIR-2 in vivo. ICP-1 dramatically stimulates AIR-2 kinase activity. This activity is not stimulated by CSC-1/BIR-1, suggesting that these two subunits function as targeting subunits for AIR-2 kinase.

Show MeSH
Related in: MedlinePlus