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cdc12p, a protein required for cytokinesis in fission yeast, is a component of the cell division ring and interacts with profilin.

Chang F, Drubin D, Nurse P - J. Cell Biol. (1997)

Bottom Line: Here we show that cdc12p is a member of a family of proteins including Drosophila diaphanous, Saccharomyces cerevisiae BNI1, and S. pombe fus1, which are involved in cytokinesis or other actin-mediated processes.Based on these patterns, we present a model in which ring assembly originates from a single point on the cortex and in which a molecular pathway for the functions of cytokinesis proteins is suggested.Finally, we found that cdc12 and cdc3 mutants show a synthetic-lethal genetic interaction, and a proline-rich domain of cdc12p binds directly to profilin cdc3p in vitro, suggesting that one function of cdc12p in ring assembly is to bind profilin.

View Article: PubMed Central - PubMed

Affiliation: Imperial Cancer Research Fund, London, United Kingdom. fc99@columbia.edu

ABSTRACT
As in many other eukaryotic cells, cell division in fission yeast depends on the assembly of an actin ring that circumscribes the middle of the cell. Schizosaccharomyces pombe cdc12 is an essential gene necessary for actin ring assembly and septum formation. Here we show that cdc12p is a member of a family of proteins including Drosophila diaphanous, Saccharomyces cerevisiae BNI1, and S. pombe fus1, which are involved in cytokinesis or other actin-mediated processes. Using indirect immunofluorescence, we show that cdc12p is located in the cell division ring and not in other actin structures. When overexpressed, cdc12p is located at a medial spot in interphase that anticipates the future ring site. cdc12p localization is altered in actin ring mutants. cdc8 (tropomyosin homologue), cdc3 (profilin homologue), and cdc15 mutants exhibit no specific cdc12p staining during mitosis. cdc4 mutant cells exhibit a medial cortical cdc12p spot in place of a ring. mid1 mutant cells generally exhibit a cdc12p spot with a single cdc12p strand extending in a random direction. Based on these patterns, we present a model in which ring assembly originates from a single point on the cortex and in which a molecular pathway for the functions of cytokinesis proteins is suggested. Finally, we found that cdc12 and cdc3 mutants show a synthetic-lethal genetic interaction, and a proline-rich domain of cdc12p binds directly to profilin cdc3p in vitro, suggesting that one function of cdc12p in ring assembly is to bind profilin.

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Localization of cdc12p in mid1 mutant cells during early  mitosis. mid1-366 mutant cells were grown in YE5S at permissive  temperature (25°C), and then shifted to restrictive temperature  (35.5°C) for 2 h. Cells were processed for immunofluorescence  with anti-cdc12 antibody, anti-tubulin antibody or anti-actin antibody, and DAPI. On the basis of spindle and nuclear morphology, cells pictured are in early mitosis, the cell cycle period  around ring formation. Note different configurations of cdc12p  dot and strand (arrows). Bar, 10 μm.
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Figure 7: Localization of cdc12p in mid1 mutant cells during early mitosis. mid1-366 mutant cells were grown in YE5S at permissive temperature (25°C), and then shifted to restrictive temperature (35.5°C) for 2 h. Cells were processed for immunofluorescence with anti-cdc12 antibody, anti-tubulin antibody or anti-actin antibody, and DAPI. On the basis of spindle and nuclear morphology, cells pictured are in early mitosis, the cell cycle period around ring formation. Note different configurations of cdc12p dot and strand (arrows). Bar, 10 μm.

Mentions: mid1-366 mutants exhibited highly variable patterns that reflect multiple defects in the spatial organization of the ring (Fig. 7; Table II). Generally, mid1 mutants had a medial cdc12p spot associated with single strand ( Fig. 7, A–C). Over 90% of the strands were associated with the nucleus at some point along the strand, and some strands even wrapped around the nucleus (Fig. 7 C). Some cells only had a medial spot of cdc12p (Fig. 7 D) or no staining at all (not shown). 30% of the spots were positioned away from the cell middle and the nucleus (Fig. 7 E), indicating an apparent defect in placing the spot. Although few (<5%) complete rings were present in early mitosis, many complete rings that were displaced and tilted (47% of cells) were seen in late mitosis (Table II; see Chang et al., 1995), suggesting that the cdc12p strand in early mitosis may organize into a displaced ring later in mitosis. Thus, mid1 mutants have defects both in guiding a strand around the circumference of the cell to form a ring and in the medial placement of the spot.


cdc12p, a protein required for cytokinesis in fission yeast, is a component of the cell division ring and interacts with profilin.

Chang F, Drubin D, Nurse P - J. Cell Biol. (1997)

Localization of cdc12p in mid1 mutant cells during early  mitosis. mid1-366 mutant cells were grown in YE5S at permissive  temperature (25°C), and then shifted to restrictive temperature  (35.5°C) for 2 h. Cells were processed for immunofluorescence  with anti-cdc12 antibody, anti-tubulin antibody or anti-actin antibody, and DAPI. On the basis of spindle and nuclear morphology, cells pictured are in early mitosis, the cell cycle period  around ring formation. Note different configurations of cdc12p  dot and strand (arrows). Bar, 10 μm.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2139860&req=5

Figure 7: Localization of cdc12p in mid1 mutant cells during early mitosis. mid1-366 mutant cells were grown in YE5S at permissive temperature (25°C), and then shifted to restrictive temperature (35.5°C) for 2 h. Cells were processed for immunofluorescence with anti-cdc12 antibody, anti-tubulin antibody or anti-actin antibody, and DAPI. On the basis of spindle and nuclear morphology, cells pictured are in early mitosis, the cell cycle period around ring formation. Note different configurations of cdc12p dot and strand (arrows). Bar, 10 μm.
Mentions: mid1-366 mutants exhibited highly variable patterns that reflect multiple defects in the spatial organization of the ring (Fig. 7; Table II). Generally, mid1 mutants had a medial cdc12p spot associated with single strand ( Fig. 7, A–C). Over 90% of the strands were associated with the nucleus at some point along the strand, and some strands even wrapped around the nucleus (Fig. 7 C). Some cells only had a medial spot of cdc12p (Fig. 7 D) or no staining at all (not shown). 30% of the spots were positioned away from the cell middle and the nucleus (Fig. 7 E), indicating an apparent defect in placing the spot. Although few (<5%) complete rings were present in early mitosis, many complete rings that were displaced and tilted (47% of cells) were seen in late mitosis (Table II; see Chang et al., 1995), suggesting that the cdc12p strand in early mitosis may organize into a displaced ring later in mitosis. Thus, mid1 mutants have defects both in guiding a strand around the circumference of the cell to form a ring and in the medial placement of the spot.

Bottom Line: Here we show that cdc12p is a member of a family of proteins including Drosophila diaphanous, Saccharomyces cerevisiae BNI1, and S. pombe fus1, which are involved in cytokinesis or other actin-mediated processes.Based on these patterns, we present a model in which ring assembly originates from a single point on the cortex and in which a molecular pathway for the functions of cytokinesis proteins is suggested.Finally, we found that cdc12 and cdc3 mutants show a synthetic-lethal genetic interaction, and a proline-rich domain of cdc12p binds directly to profilin cdc3p in vitro, suggesting that one function of cdc12p in ring assembly is to bind profilin.

View Article: PubMed Central - PubMed

Affiliation: Imperial Cancer Research Fund, London, United Kingdom. fc99@columbia.edu

ABSTRACT
As in many other eukaryotic cells, cell division in fission yeast depends on the assembly of an actin ring that circumscribes the middle of the cell. Schizosaccharomyces pombe cdc12 is an essential gene necessary for actin ring assembly and septum formation. Here we show that cdc12p is a member of a family of proteins including Drosophila diaphanous, Saccharomyces cerevisiae BNI1, and S. pombe fus1, which are involved in cytokinesis or other actin-mediated processes. Using indirect immunofluorescence, we show that cdc12p is located in the cell division ring and not in other actin structures. When overexpressed, cdc12p is located at a medial spot in interphase that anticipates the future ring site. cdc12p localization is altered in actin ring mutants. cdc8 (tropomyosin homologue), cdc3 (profilin homologue), and cdc15 mutants exhibit no specific cdc12p staining during mitosis. cdc4 mutant cells exhibit a medial cortical cdc12p spot in place of a ring. mid1 mutant cells generally exhibit a cdc12p spot with a single cdc12p strand extending in a random direction. Based on these patterns, we present a model in which ring assembly originates from a single point on the cortex and in which a molecular pathway for the functions of cytokinesis proteins is suggested. Finally, we found that cdc12 and cdc3 mutants show a synthetic-lethal genetic interaction, and a proline-rich domain of cdc12p binds directly to profilin cdc3p in vitro, suggesting that one function of cdc12p in ring assembly is to bind profilin.

Show MeSH
Related in: MedlinePlus