cdc12p, a Protein Required for Cytokinesis in Fission Yeast, Is a Component of the Cell Division Ring and Interacts with Profilin

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 syntheticlethal 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.

The Actomyosin Ring Recruits Early Secretory Compartments to the Division Site in Fission Yeast

“…To explore this question, we introduced the fluorescent markers of the secretory pathway into the cdc12-112 temperature-sensitive genetic background. The essential S. pombe formin Cdc12p plays a crucial role in actomyosin ring formation, and fission yeast cells are incapable of ring assembly when Cdc12p function is compromised (Chang et al, 1997). When grown at the restrictive temperature of 36°C, cdc12-112 mutant cells are not capable of cytokinesis but undergo the nuclear division (Arai and Mabuchi, 2002).…”

“…During early mitosis, actin is assembled into a ring structure through the action of several actin nucleating and bundling proteins and molecular motors. These include the formin Cdc12p (Chang et al, 1997), profilin Cdc3p (Balasubramanian et al, 1992), the extended Fer/CIP4 (EFC) domain protein Cdc15p (Fankhauser et al, 1995), and the myosin heavy chain Myo2p (Kitayama et al, 1997) together with its light chains Cdc4p (McCollum et al, 1995;Naqvi et al, 1999) and Rlc1p (Le Goff et al, 2000). It has been proposed that activation of the signaling cascade referred to as the septation initiation network (SIN) triggers actomyosin ring constriction upon nuclear division (for review see Krapp et al, 2004).…”

Roles of a Fimbrin and an α-Actinin-like Protein in Fission Yeast Cell Polarization and Cytokinesis

“…h Ϫ cdc3-6 P. Nurse (Nurse et al, 1976;Balasubramanian et al, 1994 (Chang et al, 1997;Eng et al, 1998) Bähler and Pringle, 1998 JB23 h Ϫ cdc14-118 leu1-32 P. Nurse (Nurse et al, 1976) (Minet et al, 1979) Hiraoka et al, 1984 a Derived by mating two haploid strains obtained from J. Kohli. b myo2-E1 was originally referred to as rng5-E1 (Balasubramanian et al, 1998;Eng et al, 1998).…”

From Function to Shape: A Novel Role of a Formin in Morphogenesis of the FungusAshbya gossypii

“…This idea was supported by comparison to the more distantly related fission yeast S. pombe, which expresses three members of the formin family with clear separation of functions. For3 is involved in cell polarity (Feierbach and Chang, 2001), Cdc12 is involved in cytokinesis (Chang et al, 1997) and Fus1 is necessary for cell fusion during mating (Petersen et al, 1998a). Although S. pombe for3⌬ had no visible actin cables (Feierbach and Chang, 2001) or the cables were shorter in size and reduced in number (Nakano et al, 2002), cells were still able to grow in a polarized manner unlike a deletion of Agbni1.…”

“…In Schizosaccharomyces pombe, three formins exist which are also involved in cell polarity and cytokinesis. The protein SpCdc12p is involved in cytokinesis (Chang et al, 1997;Kovar et al, 2003), SpFus1p in cell fusion (Petersen et al, 1998b) and SpFor3p in cell polarity control via regulation of the actin and microtubule network (Feierbach and Chang, 2001;Nakano et al, 2002). The only formin family member described so far in a filamentous fungus is the SepA protein of Aspergillus nidulans.…”