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The transcriptional repressor Kaiso localizes at the mitotic spindle and is a constituent of the pericentriolar material.

Soubry A, Staes K, Parthoens E, Noppen S, Stove C, Bogaert P, van Hengel J, van Roy F - PLoS ONE (2010)

Bottom Line: In the present study we monitored Kaiso's subcellular localization during the cell cycle and found the following: (1) during interphase, Kaiso is located not only in the nucleus, but also on microtubular structures, including the centrosome; (2) at metaphase, it is present at the centrosomes and on the spindle microtubules; (3) during telophase, it accumulates at the midbody.We found that Kaiso is a genuine PCM component that belongs to a pericentrin molecular complex.Knockdown of Kaiso accelerated cell proliferation.

View Article: PubMed Central - PubMed

Affiliation: Department for Molecular Biomedical Research, VIB, Ghent, Belgium.

ABSTRACT
Kaiso is a BTB/POZ zinc finger protein known as a transcriptional repressor. It was originally identified through its in vitro association with the Armadillo protein p120ctn. Subcellular localization of Kaiso in cell lines and in normal and cancerous human tissues revealed that its expression is not restricted to the nucleus. In the present study we monitored Kaiso's subcellular localization during the cell cycle and found the following: (1) during interphase, Kaiso is located not only in the nucleus, but also on microtubular structures, including the centrosome; (2) at metaphase, it is present at the centrosomes and on the spindle microtubules; (3) during telophase, it accumulates at the midbody. We found that Kaiso is a genuine PCM component that belongs to a pericentrin molecular complex. We analyzed the functions of different domains of Kaiso by visualizing the subcellular distribution of GFP-tagged Kaiso fragments throughout the cell cycle. Our results indicate that two domains are responsible for targeting Kaiso to the centrosomes and microtubules. The first domain, designated SA1 for spindle-associated domain 1, is located in the center of the Kaiso protein and localizes at the spindle microtubules and centrosomes; the second domain, SA2, is an evolutionarily conserved domain situated just before the zinc finger domain and might be responsible for localizing Kaiso towards the centrosomal region. Constructs containing both SA domains and Kaiso's aminoterminal BTB/POZ domain triggered the formation of abnormal centrosomes. We also observed that overexpression of longer or full-length Kaiso constructs led to mitotic cell arrest and frequent cell death. Knockdown of Kaiso accelerated cell proliferation. Our data reveal a new target for Kaiso at the centrosomes and spindle microtubules during mitosis. They also strongly imply that Kaiso's function as a transcriptional regulator might be linked to the control of the cell cycle and to cell proliferation in cancer.

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Kaiso and p120ctn localization during cytokinesis.Column A shows pictures made after focusing on the midbody of SK-LMS-1 cells: Kaiso is present at the midbody (long arrow) while p120ctn is located at the cleavage furrow (double short arrow) between the two forming cells. Column B shows pictures of the same cells while focusing on the protrusions at the cell borders. Kaiso and p120ctn partly colocalize there. Pictures in column C are magnifications of the free edge of one of the daughter cells. Cells were stained with a polyclonal antibody (S1337) for Kaiso detection, and with a monoclonal antibody (pp120) for p120ctn detection, followed by an Alexa 488-conjugated anti-rabbit secondary antibody for Kaiso, and an Alexa 594-conjugated anti-mouse secondary antibody for p120ctn. DNA was stained with DAPI. Cells were imaged (63× objective lens) with a Zeiss Axiophot microscope.
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pone-0009203-g010: Kaiso and p120ctn localization during cytokinesis.Column A shows pictures made after focusing on the midbody of SK-LMS-1 cells: Kaiso is present at the midbody (long arrow) while p120ctn is located at the cleavage furrow (double short arrow) between the two forming cells. Column B shows pictures of the same cells while focusing on the protrusions at the cell borders. Kaiso and p120ctn partly colocalize there. Pictures in column C are magnifications of the free edge of one of the daughter cells. Cells were stained with a polyclonal antibody (S1337) for Kaiso detection, and with a monoclonal antibody (pp120) for p120ctn detection, followed by an Alexa 488-conjugated anti-rabbit secondary antibody for Kaiso, and an Alexa 594-conjugated anti-mouse secondary antibody for p120ctn. DNA was stained with DAPI. Cells were imaged (63× objective lens) with a Zeiss Axiophot microscope.

Mentions: The unexpected presence of Kaiso at the mitotic spindle and the centrosomes prompted us to reexamine more precisely the expression of Kaiso's binding partner p120ctn at all stages of mitosis. Using the mouse monoclonal antibody pp120, we did not observe colocalization of endogenous p120ctn with Kaiso at the mitotic spindle or centrosomes in the cell lines HT29, SW48, SK-LMS-1, MCF-7, MCF-10A, HEK293, HeLa, MDA-MB-435, Ptk-2, L929, HL-1 and MDCK. In contrast, we observed endogenous p120ctn during cytokinesis at the cleavage furrow in a ring-shaped form and in the protrusions at the distal edges of the two forming daughter cells (Fig. 10). At this very late stage in cell division, p120ctn and Kaiso largely colocalized at these protrusions but not in the midbody region.


The transcriptional repressor Kaiso localizes at the mitotic spindle and is a constituent of the pericentriolar material.

Soubry A, Staes K, Parthoens E, Noppen S, Stove C, Bogaert P, van Hengel J, van Roy F - PLoS ONE (2010)

Kaiso and p120ctn localization during cytokinesis.Column A shows pictures made after focusing on the midbody of SK-LMS-1 cells: Kaiso is present at the midbody (long arrow) while p120ctn is located at the cleavage furrow (double short arrow) between the two forming cells. Column B shows pictures of the same cells while focusing on the protrusions at the cell borders. Kaiso and p120ctn partly colocalize there. Pictures in column C are magnifications of the free edge of one of the daughter cells. Cells were stained with a polyclonal antibody (S1337) for Kaiso detection, and with a monoclonal antibody (pp120) for p120ctn detection, followed by an Alexa 488-conjugated anti-rabbit secondary antibody for Kaiso, and an Alexa 594-conjugated anti-mouse secondary antibody for p120ctn. DNA was stained with DAPI. Cells were imaged (63× objective lens) with a Zeiss Axiophot microscope.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2821401&req=5

pone-0009203-g010: Kaiso and p120ctn localization during cytokinesis.Column A shows pictures made after focusing on the midbody of SK-LMS-1 cells: Kaiso is present at the midbody (long arrow) while p120ctn is located at the cleavage furrow (double short arrow) between the two forming cells. Column B shows pictures of the same cells while focusing on the protrusions at the cell borders. Kaiso and p120ctn partly colocalize there. Pictures in column C are magnifications of the free edge of one of the daughter cells. Cells were stained with a polyclonal antibody (S1337) for Kaiso detection, and with a monoclonal antibody (pp120) for p120ctn detection, followed by an Alexa 488-conjugated anti-rabbit secondary antibody for Kaiso, and an Alexa 594-conjugated anti-mouse secondary antibody for p120ctn. DNA was stained with DAPI. Cells were imaged (63× objective lens) with a Zeiss Axiophot microscope.
Mentions: The unexpected presence of Kaiso at the mitotic spindle and the centrosomes prompted us to reexamine more precisely the expression of Kaiso's binding partner p120ctn at all stages of mitosis. Using the mouse monoclonal antibody pp120, we did not observe colocalization of endogenous p120ctn with Kaiso at the mitotic spindle or centrosomes in the cell lines HT29, SW48, SK-LMS-1, MCF-7, MCF-10A, HEK293, HeLa, MDA-MB-435, Ptk-2, L929, HL-1 and MDCK. In contrast, we observed endogenous p120ctn during cytokinesis at the cleavage furrow in a ring-shaped form and in the protrusions at the distal edges of the two forming daughter cells (Fig. 10). At this very late stage in cell division, p120ctn and Kaiso largely colocalized at these protrusions but not in the midbody region.

Bottom Line: In the present study we monitored Kaiso's subcellular localization during the cell cycle and found the following: (1) during interphase, Kaiso is located not only in the nucleus, but also on microtubular structures, including the centrosome; (2) at metaphase, it is present at the centrosomes and on the spindle microtubules; (3) during telophase, it accumulates at the midbody.We found that Kaiso is a genuine PCM component that belongs to a pericentrin molecular complex.Knockdown of Kaiso accelerated cell proliferation.

View Article: PubMed Central - PubMed

Affiliation: Department for Molecular Biomedical Research, VIB, Ghent, Belgium.

ABSTRACT
Kaiso is a BTB/POZ zinc finger protein known as a transcriptional repressor. It was originally identified through its in vitro association with the Armadillo protein p120ctn. Subcellular localization of Kaiso in cell lines and in normal and cancerous human tissues revealed that its expression is not restricted to the nucleus. In the present study we monitored Kaiso's subcellular localization during the cell cycle and found the following: (1) during interphase, Kaiso is located not only in the nucleus, but also on microtubular structures, including the centrosome; (2) at metaphase, it is present at the centrosomes and on the spindle microtubules; (3) during telophase, it accumulates at the midbody. We found that Kaiso is a genuine PCM component that belongs to a pericentrin molecular complex. We analyzed the functions of different domains of Kaiso by visualizing the subcellular distribution of GFP-tagged Kaiso fragments throughout the cell cycle. Our results indicate that two domains are responsible for targeting Kaiso to the centrosomes and microtubules. The first domain, designated SA1 for spindle-associated domain 1, is located in the center of the Kaiso protein and localizes at the spindle microtubules and centrosomes; the second domain, SA2, is an evolutionarily conserved domain situated just before the zinc finger domain and might be responsible for localizing Kaiso towards the centrosomal region. Constructs containing both SA domains and Kaiso's aminoterminal BTB/POZ domain triggered the formation of abnormal centrosomes. We also observed that overexpression of longer or full-length Kaiso constructs led to mitotic cell arrest and frequent cell death. Knockdown of Kaiso accelerated cell proliferation. Our data reveal a new target for Kaiso at the centrosomes and spindle microtubules during mitosis. They also strongly imply that Kaiso's function as a transcriptional regulator might be linked to the control of the cell cycle and to cell proliferation in cancer.

Show MeSH
Related in: MedlinePlus