scholarly journals Characterization of the roles of Blt1p in fission yeast cytokinesis

2014 ◽  
Vol 25 (13) ◽  
pp. 1946-1957 ◽  
Author(s):  
John W. Goss ◽  
Sunhee Kim ◽  
Hannah Bledsoe ◽  
Thomas D. Pollard
Keyword(s):  
Cell Division ◽  
Fission Yeast ◽  
Cell Separation ◽  
Analytical Ultracentrifugation ◽  
Contractile Ring ◽  
Glucan Synthase ◽  
Temporal Regulation ◽  
Septation Initiation Network ◽  
Ring Constriction

Spatial and temporal regulation of cytokinesis is essential for cell division, yet the mechanisms that control the formation and constriction of the contractile ring are incompletely understood. In the fission yeast Schizosaccharomyces pombe proteins that contribute to the cytokinetic contractile ring accumulate during interphase in nodes—precursor structures around the equatorial cortex. During mitosis, additional proteins join these nodes, which condense to form the contractile ring. The cytokinesis protein Blt1p is unique in being present continuously in nodes from early interphase through to the contractile ring until cell separation. Blt1p was shown to stabilize interphase nodes, but its functions later in mitosis were unclear. We use analytical ultracentrifugation to show that purified Blt1p is a tetramer. We find that Blt1p interacts physically with Sid2p and Mob1p, a protein kinase complex of the septation initiation network, and confirm known interactions with F-BAR protein Cdc15p. Contractile rings assemble normally in blt1∆ cells, but the initiation of ring constriction and completion of cell division are delayed. We find three defects that likely contribute to this delay. Without Blt1p, contractile rings recruited and retained less Sid2p/Mob1p and Clp1p phosphatase, and β-glucan synthase Bgs1p accumulated slowly at the cleavage site.

scholarly journals Scw1p Antagonizes the Septation Initiation Network To Regulate Septum Formation and Cell Separation in the Fission Yeast Schizosaccharomyces pombe

2003 ◽  
Vol 2 (3) ◽  
pp. 510-520 ◽  
Author(s):  
Quan-Wen Jin ◽  
Dannel McCollum
Keyword(s):  
Schizosaccharomyces Pombe ◽  
Fission Yeast ◽  
Cell Separation ◽  
Deletion Mutant ◽  
Temperature Sensitive ◽  
Growth Defects ◽  
Septum Formation ◽  
Primary Septum ◽  
Septation Initiation Network ◽  
Ring Constriction

ABSTRACT Cytokinesis in the fission yeast Schizosaccharomyces pombe is regulated by a signaling pathway termed the septation initiation network (SIN). The SIN is essential for initiation of actomyosin ring constriction and septum formation. In a screen to search for mutations that can rescue the sid2-250 SIN mutant, we obtained scw1-18. Both the scw1-18 mutant and the scw1 deletion mutant (scw1Δ mutant), have defects in cell separation. Both the scw1-18 and scw1Δ mutations rescue the growth defects of not just the sid2-250 mutant but also the other temperature-sensitive SIN mutants. Other cytokinesis mutants, such as those defective for actomyosin ring formation, are not rescued by scw1Δ. scw1Δ does not seem to rescue the SIN by restoring SIN signaling defects. However, scw1Δ may function downstream of the SIN to promote septum formation, since scw1Δ can rescue the septum formation defects of the cps1-191β-1,3-glucan synthase mutant, which is required for synthesis of the primary septum.

scholarly journals Profilin-mediated Competition between Capping Protein and Formin Cdc12p during Cytokinesis in Fission Yeast

2005 ◽  
Vol 16 (5) ◽  
pp. 2313-2324 ◽  
Author(s):  
David R. Kovar ◽  
Jian-Qiu Wu ◽  
Thomas D. Pollard
Keyword(s):  
Fission Yeast ◽  
Actin Filament ◽  
Actin Filaments ◽  
Cell Separation ◽  
The Other ◽  
Temperature Sensitive ◽  
Contractile Ring ◽  
Capping Protein ◽  
Division Site ◽  
Ring Constriction

Fission yeast capping protein SpCP is a heterodimer of two subunits (Acp1p and Acp2p) that binds actin filament barbed ends. Neither acp1 nor acp2 is required for viability, but cells lacking either or both subunits have cytokinesis defects under stressful conditions, including elevated temperature, osmotic stress, or in combination with numerous mild mutations in genes important for cytokinesis. Defects arise as the contractile ring constricts and disassembles, resulting in delays in cell separation. Genetic and biochemical interactions show that the cytokinesis formin Cdc12p competes with capping protein for actin filament barbed ends in cells. Deletion of acp2 partly suppresses cytokinesis defects in temperature-sensitive cdc12-112 cells and mild overexpression of capping protein kills cdc12-112 cells. Biochemically, profilin has opposite effects on filaments capped with Cdc12p and capping protein. Profilin depolymerizes actin filaments capped by capping protein but allows filaments capped by Cdc12p to grow at their barbed ends. Once associated with a barbed end, either Cdc12p or capping protein prevents the other from influencing polymerization at that end. Given that capping protein arrives at the division site 20 min later than Cdc12p, capping protein may slowly replace Cdc12p on filament barbed ends in preparation for filament disassembly during ring constriction.

scholarly journals Cooperation between Rho-GEF Gef2 and its binding partner Nod1 in the regulation of fission yeast cytokinesis

2013 ◽  
Vol 24 (20) ◽  
pp. 3187-3204 ◽  
Author(s):  
Yi-Hua Zhu ◽  
Yanfang Ye ◽  
Zhengrong Wu ◽  
Jian-Qiu Wu
Keyword(s):  
Fission Yeast ◽  
Rho Gtpases ◽  
Adaptor Protein ◽  
Nucleotide Exchange ◽  
Contractile Ring ◽  
Temporal Regulation ◽  
Division Site ◽  
Septation Initiation Network ◽  
Rho Gef

Cytokinesis is the last step of the cell-division cycle, which requires precise spatial and temporal regulation to ensure genetic stability. Rho guanine nucleotide exchange factors (Rho GEFs) and Rho GTPases are among the key regulators of cytokinesis. We previously found that putative Rho-GEF Gef2 coordinates with Polo kinase Plo1 to control the medial cortical localization of anillin-like protein Mid1 in fission yeast. Here we show that an adaptor protein, Nod1, colocalizes with Gef2 in the contractile ring and its precursor cortical nodes. Like gef2∆, nod1∆ has strong genetic interactions with various cytokinesis mutants involved in division-site positioning, suggesting a role of Nod1 in early cytokinesis. We find that Nod1 and Gef2 interact through the C-termini, which is important for their localization. The contractile-ring localization of Nod1 and Gef2 also depends on the interaction between Nod1 and the F-BAR protein Cdc15, where the Nod1/Gef2 complex plays a role in contractile-ring maintenance and affects the septation initiation network. Moreover, Gef2 binds to purified GTPases Rho1, Rho4, and Rho5 in vitro. Taken together, our data indicate that Nod1 and Gef2 function cooperatively in a protein complex to regulate fission yeast cytokinesis.

scholarly journals Calcium spikes accompany cleavage furrow ingression and cell separation during fission yeast cytokinesis

2021 ◽  
Vol 32 (1) ◽  
pp. 15-27 ◽  
Author(s):  
Abhishek Poddar ◽  
Oumou Sidibe ◽  
Aniruddha Ray ◽  
Qian Chen
Keyword(s):  
Fission Yeast ◽  
Cell Separation ◽  
Cleavage Furrow ◽  
Cell Integrity ◽  
Embryonic Cells ◽  
Contractile Ring ◽  
Calcium Spikes ◽  
Division Plane ◽  
Ring Constriction ◽  
And Function

Calcium rises transiently at the division plane during cytokinesis of embryonic cells, but the conservation and function of such calcium transients remain unclear. We discovered similar calcium spikes during fission yeast cytokinesis, and demonstrated that calcium promotes contractile ring constriction and daughter cell integrity.

scholarly journals Fission yeast Cyk3p is a transglutaminase-like protein that participates in cytokinesis and cell morphogenesis

2012 ◽  
Vol 23 (13) ◽  
pp. 2433-2444 ◽  
Author(s):  
Luther W. Pollard ◽  
Masayuki Onishi ◽  
John R. Pringle ◽  
Matthew Lord
Keyword(s):  
Fission Yeast ◽  
Primary Role ◽  
Cell Integrity ◽  
Cell Morphogenesis ◽  
Contractile Ring ◽  
Physiological Importance ◽  
Complex Process ◽  
Catalytic Active Site ◽  
Thiol Proteases ◽  
Ring Constriction

Cell morphogenesis is a complex process that relies on a diverse array of proteins and pathways. We have identified a transglutaminase-like protein (Cyk3p) that functions in fission yeast morphogenesis. The phenotype of a cyk3 knockout strain indicates a primary role for Cyk3p in cytokinesis. Correspondingly, Cyk3p localizes both to the actomyosin contractile ring and the division septum, promoting ring constriction, septation, and subsequent cell separation following ring disassembly. In addition, Cyk3p localizes to polarized growth sites and plays a role in cell shape determination, and it also appears to contribute to cell integrity during stationary phase, given its accumulation as dynamic puncta at the cortex of such cells. Our results and the conservation of Cyk3p across fungi point to a role in cell wall synthesis and remodeling. Cyk3p possesses a transglutaminase domain that is essential for function, even though it lacks the catalytic active site. In a wider sense, our work illustrates the physiological importance of inactive members of the transglutaminase family, which are found throughout eukaryotes. We suggest that the proposed evolution of animal transglutaminase cross-linking activity from ancestral bacterial thiol proteases was accompanied by the emergence of a subclass whose function does not depend on enzymatic activity.

scholarly journals A Link between Aurora Kinase and Clp1/Cdc14 Regulation Uncovered by the Identification of a Fission Yeast Borealin-Like Protein

2009 ◽  
Vol 20 (16) ◽  
pp. 3646-3659 ◽  
Author(s):  
K. Adam Bohnert ◽  
Jun-Song Chen ◽  
Dawn M. Clifford ◽  
Craig W. Vander Kooi ◽  
Kathleen L. Gould
Keyword(s):  
Cell Division ◽  
Schizosaccharomyces Pombe ◽  
Fission Yeast ◽  
Kinase Activity ◽  
Sequence Similarity ◽  
Aurora Kinase ◽  
Genetic Interactions ◽  
Aurora B ◽  
Contractile Ring ◽  
Chromosomal Passenger

The chromosomal passenger complex (CPC) regulates various events in cell division. This complex is composed of a catalytic subunit, Aurora B kinase, and three nonenzymatic subunits, INCENP, Survivin, and Borealin. Together, these four subunits interdependently regulate CPC function, and they are highly conserved among eukaryotes. However, a Borealin homologue has never been characterized in the fission yeast, Schizosaccharomyces pombe . Here, we isolate a previously uncharacterized S. pombe protein through association with the Cdc14 phosphatase homologue, Clp1/Flp1, and identify it as a Borealin-like member of the CPC. Nbl1 (novel Borealin-like 1) physically associates with known CPC components, affects the kinase activity and stability of the S. pombe Aurora B homologue, Ark1, colocalizes with known CPC subunits during mitosis, and shows sequence similarity to human Borealin. Further analysis of the Clp1–Nbl1 interaction indicates that Clp1 requires CPC activity for proper accumulation at the contractile ring (CR). Consistent with this, we describe negative genetic interactions between mutant alleles of CPC and CR components. Thus, this study characterizes a fission yeast Borealin homologue and reveals a previously unrecognized connection between the CPC and the process of cytokinesis in S. pombe .

scholarly journals Mid2p stabilizes septin rings during cytokinesis in fission yeast

2003 ◽  
Vol 160 (7) ◽  
pp. 1083-1092 ◽  
Author(s):  
Ana Berlin ◽  
Anne Paoletti ◽  
Fred Chang
Keyword(s):  
Fission Yeast ◽  
Cell Separation ◽  
Sequence Similarity ◽  
Ring Closure ◽  
Pleckstrin Homology Domain ◽  
Wild Type ◽  
Contractile Ring ◽  
Single Ring ◽  
And Function ◽  
Cell Cell

Septins are filament-forming proteins with a conserved role in cytokinesis. In the fission yeast Schizosaccharomyces pombe, septin rings appear to be involved primarily in cell–cell separation, a late stage in cytokinesis. Here, we identified a protein Mid2p on the basis of its sequence similarity to S. pombe Mid1p, Saccharomyces cerevisiae Bud4p, and Candida albicans Int1p. Like septin mutants, mid2Δ mutants had delays in cell–cell separation. mid2Δ mutants were defective in septin organization but not contractile ring closure or septum formation. In wild-type cells, septins assembled first during mitosis in a single ring and during septation developed into double rings that did not contract. In mid2Δ cells, septins initially assembled in a single ring but during septation appeared in the cleavage furrow, forming a washer or disc structure. FRAP studies showed that septins are stable in wild-type cells but exchange 30-fold more rapidly in mid2Δ cells. Mid2p colocalized with septins and required septins for its localization. A COOH-terminal pleckstrin homology domain of Mid2p was required for its localization and function. No genetic interactions were found between mid2 and the related gene mid1. Thus, these studies identify a new factor responsible for the proper stability and function of septins during cytokinesis.

scholarly journals The Localization of the Integral Membrane Protein Cps1p to the Cell Division Site is Dependent on the Actomyosin Ring and the Septation-Inducing Network inSchizosaccharomyces pombe

2002 ◽  
Vol 13 (3) ◽  
pp. 989-1000 ◽  
Author(s):  
Jianhua Liu ◽  
Xie Tang ◽  
Hongyan Wang ◽  
Snezhana Oliferenko ◽  
Mohan K. Balasubramanian
Keyword(s):  
Cell Division ◽  
Membrane Protein ◽  
Integral Membrane Protein ◽  
Wall Material ◽  
Contractile Ring ◽  
Division Site ◽  
Ring Assembly ◽  
Independent Mechanism ◽  
Ring Constriction ◽  
Initial Assembly

Schizosaccharomyces pombe cells divide by medial fission through the use of an actomyosin-based contractile ring. Constriction of the actomyosin ring is accompanied by the centripetal addition of new membranes and cell wall material. In this article, we characterize the mechanism responsible for the localization of Cps1p, a septum-synthesizing 1,3-β-glucan synthase, to the division site during cytokinesis. We show that Cps1p is an integral membrane protein that localizes to the cell division site late in anaphase. Neither F-actin nor microtubules are essential for the initial assembly of Cps1p to the medial division site. F-actin, but not microtubules, is however important for the eventual incorporation of Cps1p into the actomyosin ring. Assembly of Cps1p into the cell division ring is also dependent on the septation-inducing network (SIN) proteins that regulate division septum formation after assembly of the actomyosin ring. Fluorescence-recovery after-photobleaching experiments reveal that Cps1p does not diffuse appreciably within the plasma membrane and is retained at the division site by a mechanism that does not depend on an intact F-actin cytoskeleton. We conclude that the actomyosin ring serves as a spatial cue for Cps1p localization, whereas the maintenance of Cps1p at the division site occurs by a novel F-actin– and microtubule-independent mechanism. Furthermore, we propose that the SIN proteins ensure localization of Cps1p at the appropriate point in the cell cycle.

scholarly journals Fission yeast TRP channel Pkd2p localizes to the cleavage furrow and regulates cell separation during cytokinesis

2019 ◽  
Vol 30 (15) ◽  
pp. 1791-1804 ◽  
Author(s):  
Zachary Morris ◽  
Debatrayee Sinha ◽  
Abhishek Poddar ◽  
Brittni Morris ◽  
Qian Chen
Keyword(s):  
Fission Yeast ◽  
Cell Separation ◽  
Secretory Pathway ◽  
Transient Receptor Potential ◽  
Turgor Pressure ◽  
Receptor Potential ◽  
Mitogen Activated Protein Kinase ◽  
Force Sensing ◽  
Cleavage Furrow ◽  
Contractile Ring

Force plays a central role in separating daughter cells during cytokinesis, the last stage of cell division. However, the mechanism of force sensing during cytokinesis remains unknown. Here we discovered that Pkd2p, a putative force-sensing transient receptor potential channel, localizes to the cleavage furrow during cytokinesis of the fission yeast, Schizosaccharomyces pombe. Pkd2p, whose human homologues are associated with autosomal polycystic kidney disease, is an essential protein whose localization depends on the contractile ring and the secretory pathway. We identified and characterized a novel pkd2 mutant pkd2-81KD. The pkd2 mutant cells show signs of osmotic stress, including temporary shrinking, paused turnover of the cytoskeletal structures, and hyperactivated mitogen-activated protein kinase signaling. During cytokinesis, although the contractile ring constricts more rapidly in the pkd2 mutant than the wild-type cells (50% higher), the cell separation in the mutant is slower and often incomplete. These cytokinesis defects are also consistent with misregulated turgor pressure. Finally, the pkd2 mutant exhibits strong genetic interactions with two mutants of the septation initiation network pathway, a signaling cascade essential for cytokinesis. We propose that Pkd2p modulates osmotic homeostasis and is potentially a novel regulator of cytokinesis.

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