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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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A model for the establishment of the division site in S.  pombe. (A and B) In interphase, a marker spot is established at  the cell middle, possibly by a signal from the nucleus. This spot  may contain cdc12p; alternatively, upon overexpression, cdc12p  may accumulate at such a structure. (C) In early mitosis, the spot  remains on the cortex. (D) In early mitosis, the ring forms at the  site marked by the spot by extension of a strand from the spot  around the circumference of the cell. (E) During anaphase, the  ring becomes more robust. (F) After nuclear division, the ring  closes during septation and cell division. Roles of the actin ring  genes are inferred from cdc12p localization in mutants. Aspects  of this model are inferred from cdc12p overexpression and mutant data. Alternate models are discussed in the text.
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Figure 10: A model for the establishment of the division site in S. pombe. (A and B) In interphase, a marker spot is established at the cell middle, possibly by a signal from the nucleus. This spot may contain cdc12p; alternatively, upon overexpression, cdc12p may accumulate at such a structure. (C) In early mitosis, the spot remains on the cortex. (D) In early mitosis, the ring forms at the site marked by the spot by extension of a strand from the spot around the circumference of the cell. (E) During anaphase, the ring becomes more robust. (F) After nuclear division, the ring closes during septation and cell division. Roles of the actin ring genes are inferred from cdc12p localization in mutants. Aspects of this model are inferred from cdc12p overexpression and mutant data. Alternate models are discussed in the text.

Mentions: Analysis of cdc12p localization in different cell types revealed intriguing novel patterns that suggest that the site of ring assembly is initiated from a single point (Fig. 10). In cdc12p-overexpressing cells, the cdc12p was localized at a single medial spot between the nucleus and cortex during late interphase and early mitosis (Figs. 4, 5, and 7). This cdc12p spot was located precisely at the future site of ring assembly and generally did not include F-actin. It thus preceded ring assembly and appeared to mark the future division site.


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)

A model for the establishment of the division site in S.  pombe. (A and B) In interphase, a marker spot is established at  the cell middle, possibly by a signal from the nucleus. This spot  may contain cdc12p; alternatively, upon overexpression, cdc12p  may accumulate at such a structure. (C) In early mitosis, the spot  remains on the cortex. (D) In early mitosis, the ring forms at the  site marked by the spot by extension of a strand from the spot  around the circumference of the cell. (E) During anaphase, the  ring becomes more robust. (F) After nuclear division, the ring  closes during septation and cell division. Roles of the actin ring  genes are inferred from cdc12p localization in mutants. Aspects  of this model are inferred from cdc12p overexpression and mutant data. Alternate models are discussed in the text.
© Copyright Policy
Related In: Results  -  Collection

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

Figure 10: A model for the establishment of the division site in S. pombe. (A and B) In interphase, a marker spot is established at the cell middle, possibly by a signal from the nucleus. This spot may contain cdc12p; alternatively, upon overexpression, cdc12p may accumulate at such a structure. (C) In early mitosis, the spot remains on the cortex. (D) In early mitosis, the ring forms at the site marked by the spot by extension of a strand from the spot around the circumference of the cell. (E) During anaphase, the ring becomes more robust. (F) After nuclear division, the ring closes during septation and cell division. Roles of the actin ring genes are inferred from cdc12p localization in mutants. Aspects of this model are inferred from cdc12p overexpression and mutant data. Alternate models are discussed in the text.
Mentions: Analysis of cdc12p localization in different cell types revealed intriguing novel patterns that suggest that the site of ring assembly is initiated from a single point (Fig. 10). In cdc12p-overexpressing cells, the cdc12p was localized at a single medial spot between the nucleus and cortex during late interphase and early mitosis (Figs. 4, 5, and 7). This cdc12p spot was located precisely at the future site of ring assembly and generally did not include F-actin. It thus preceded ring assembly and appeared to mark the future division site.

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