scholarly journals Involvement of the septation initiation network in events during cytokinesis in fission yeast

2018 ◽  
Vol 131 (16) ◽  
pp. jcs216895 ◽  
Author(s):  
Sumit K. Dey ◽  
Thomas D. Pollard
Keyword(s):  
Fission Yeast ◽  
Septation Initiation Network

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 The Meiosis-Specific Sid2p-related Protein Slk1p Regulates Forespore Membrane Assembly in Fission Yeast

2008 ◽  
Vol 19 (9) ◽  
pp. 3676-3690 ◽  
Author(s):  
Hongyan Yan ◽  
Wanzhong Ge ◽  
Ting Gang Chew ◽  
Jeng Yeong Chow ◽  
Dannel McCollum ◽  
...  
Keyword(s):  
Fission Yeast ◽  
Essential Role ◽  
Spindle Pole ◽  
Dependent Manner ◽  
Related Protein ◽  
Membrane Assembly ◽  
Daughter Cells ◽  
Spindle Pole Bodies ◽  
Septation Initiation Network ◽  
Secretory Apparatus

Cytokinesis in all organisms involves the creation of membranous barriers that demarcate individual daughter cells. In fission yeast, a signaling module termed the septation initiation network (SIN) plays an essential role in the assembly of new membranes and cell wall during cytokinesis. In this study, we have characterized Slk1p, a protein-kinase related to the SIN component Sid2p. Slk1p is expressed specifically during meiosis and localizes to the spindle pole bodies (SPBs) during meiosis I and II in a SIN-dependent manner. Slk1p also localizes to the forespore membrane during sporulation. Cells lacking Slk1p display defects associated with sporulation, leading frequently to the formation of asci with smaller and/or fewer spores. The ability of slk1Δ cells to sporulate, albeit inefficiently, is fully abolished upon compromise of function of Sid2p, suggesting that Slk1p and Sid2p play overlapping roles in sporulation. Interestingly, increased expression of the syntaxin Psy1p rescues the sporulation defect of sid2-250 slk1Δ. Thus, it is likely that Slk1p and Sid2p play a role in forespore membrane assembly by facilitating recruitment of components of the secretory apparatus, such as Psy1p, to allow membrane expansion. These studies thereby provide a novel link between the SIN and vesicle trafficking during cytokinesis.

scholarly journals Localization of Fission Yeast Type II Myosin, Myo2, to the Cytokinetic Actin Ring Is Regulated by Phosphorylation of a C-Terminal Coiled-Coil Domain and Requires a Functional Septation Initiation Network

2001 ◽  
Vol 12 (12) ◽  
pp. 4044-4053 ◽  
Author(s):  
Daniel P. Mulvihill ◽  
Caroline Barretto ◽  
Jeremy S. Hyams
Keyword(s):  
Fission Yeast ◽  
Fluorescent Protein ◽  
Coiled Coil ◽  
Ring Formation ◽  
Restrictive Temperature ◽  
Actin Ring ◽  
Septation Initiation Network ◽  
Green Fluorescent ◽  
Type Ii Myosin ◽  
The Relationship

Myo2 truncations fused to green fluorescent protein (GFP) defined a C-terminal domain essential for the localization of Myo2 to the cytokinetic actin ring (CAR). The localization domain contained two predicted phosphorylation sites. Mutation of serine 1518 to alanine (S1518A) abolished Myo2 localization, whereas Myo2 with a glutamic acid at this position (S1518E) localized to the CAR. GFP-Myo2 formed rings in the septation initiation kinase (SIN) mutant cdc7-24 at 25°C but not at 36°C. GFP-Myo2S1518E rings persisted at 36°C incdc7-24 but not in another SIN kinase mutant,sid2-250. To further examine the relationship between Myo2 and the SIN pathway, the chromosomal copy ofmyo2+was fused to GFP (strainmyo2-gc). Myo2 ring formation was abolished in the double mutants myo2-gc cdc7.24 and myo2-gc sid2-250 at the restrictive temperature. In contrast, activation of the SIN pathway in the double mutant myo2-gc cdc16-116 resulted in the formation of Myo2 rings which subsequently collapsed at 36°C. We conclude that the SIN pathway that controls septation in fission yeast also regulates Myo2 ring formation and contraction. Cdc7 and Sid2 are involved in ring formation, in the case of Cdc7 by phosphorylation of a single serine residue in the Myo2 tail. Other kinases and/or phosphatases may control ring contraction.

An overview of the fission yeast septation initiation network (SIN)

2008 ◽  
Vol 36 (3) ◽  
pp. 411-415 ◽  
Author(s):  
Andrea Krapp ◽  
Viesturs Simanis
Keyword(s):  
Cell Cycle ◽  
Signal Transduction ◽  
Schizosaccharomyces Pombe ◽  
Fission Yeast ◽  
Protein Kinases ◽  
Signal Transduction Network ◽  
Septum Formation ◽  
Ras Superfamily ◽  
Septation Initiation Network

The fission yeast septation initiation network, or SIN, is a signal transduction network that is required for septum formation in Schizosaccharomyces pombe. Its activity is tightly regulated through the cell cycle, to ensure proper co-ordination of mitosis and cytokinesis. SIN signalling requires three protein kinases for its function and is mediated by a ras-superfamily GTPase. We discuss the elements of the SIN and how they are regulated.

scholarly journals A Novel Role of Dma1 in Regulating Forespore Membrane Assembly and Sporulation in Fission Yeast

2010 ◽  
Vol 21 (24) ◽  
pp. 4349-4360 ◽  
Author(s):  
Wen-zhu Li ◽  
Zhi-yong Yu ◽  
Peng-fei Ma ◽  
Yamei Wang ◽  
Quan-wen Jin
Keyword(s):  
Fission Yeast ◽  
Mitotic Spindle ◽  
Nuclear Division ◽  
Scaffold Proteins ◽  
Related Protein ◽  
Membrane Assembly ◽  
Meiotic Progression ◽  
Septation Initiation Network ◽  
Specific Proteins

In fission yeast Schizosaccharomyces pombe, a diploid mother cell differentiates into an ascus containing four haploid ascospores following meiotic nuclear divisions, through a process called sporulation. Several meiosis-specific proteins of fission yeast have been identified to play essential roles in meiotic progression and sporulation. We report here an unexpected function of mitotic spindle checkpoint protein Dma1 in proper spore formation. Consistent with its function in sporulation, expression of dma1+ is up-regulated during meiosis I and II. We showed that Dma1 localizes to the SPB during meiosis and the maintenance of this localization at meiosis II depends on septation initiation network (SIN) scaffold proteins Sid4 and Cdc11. Cells lacking Dma1 display defects associated with sporulation but not nuclear division, leading frequently to formation of asci with fewer spores. Our genetic analyses support the notion that Dma1 functions in parallel with the meiosis-specific Sid2-related protein kinase Slk1/Mug27 and the SIN signaling during sporulation, possibly through regulating proper forespore membrane assembly. Our studies therefore revealed a novel function of Dma1 in regulating sporulation in fission yeast.

scholarly journals Roles of Pdk1p, a Fission Yeast Protein Related to Phosphoinositide-dependent Protein Kinase, in the Regulation of Mitosis and Cytokinesis

2005 ◽  
Vol 16 (7) ◽  
pp. 3162-3175 ◽  
Author(s):  
Andrea Bimbó ◽  
Jianhua Liu ◽  
Mohan K. Balasubramanian
Keyword(s):  
Protein Kinase ◽  
Fission Yeast ◽  
Spindle Pole Body ◽  
Spindle Pole ◽  
Yeast Protein ◽  
Dependent Protein Kinase ◽  
Multiple Processes ◽  
Regulate Cell Growth ◽  
Septation Initiation Network ◽  
Dependent Protein

Proteins related to the phosphoinositide-dependent protein kinase family have been identified in the majority of eukaryotes. Although much is known about upstream mechanisms that regulate the PDK1-family of kinases in metazoans, how these kinases regulate cell growth and division remains unclear. Here, we characterize a fission yeast protein related to members of this family, which we have termed Pdk1p. Pdk1p localizes to the spindle pole body and the actomyosin ring in early mitotic cells. Cells deleted for pdk1 display multiple defects in mitosis and cytokinesis, all of which are exacerbated when the function of fission yeast polo kinase, Plo1p, is partially compromised. We conclude that Pdk1p functions in concert with Plo1p to regulate multiple processes such as the establishment of a bipolar mitotic spindle, transition to anaphase, placement of the actomyosin ring and proper execution of cytokinesis. We also present evidence that the effects of Pdk1p on cytokinesis are likely mediated via the fission yeast anillin-related protein, Mid1p, and the septation initiation network.

scholarly journals Cytokinetic nodes in fission yeast arise from two distinct types of nodes that merge during interphase

2014 ◽  
Vol 204 (6) ◽  
pp. 977-988 ◽  
Author(s):  
Matthew Akamatsu ◽  
Julien Berro ◽  
Kai-Ming Pu ◽  
Irene R. Tebbs ◽  
Thomas D. Pollard
Keyword(s):  
Fission Yeast ◽  
Fusion Proteins ◽  
Contractile Ring ◽  
Guanosine Triphosphate ◽  
Quantitative Measurements ◽  
Capture Mechanism ◽  
Septation Initiation Network ◽  
Stationary Type

We investigated the assembly of cortical nodes that generate the cytokinetic contractile ring in fission yeast. Observations of cells expressing fluorescent fusion proteins revealed two types of interphase nodes. Type 1 nodes containing kinase Cdr1p, kinase Cdr2p, and anillin Mid1p form in the cortex around the nucleus early in G2. Type 2 nodes with protein Blt1p, guanosine triphosphate exchange factor Gef2p, and kinesin Klp8p emerge from contractile ring remnants. Quantitative measurements and computer simulations showed that these two types of nodes come together by a diffuse-and-capture mechanism: type 2 nodes diffuse to the equator and are captured by stationary type 1 nodes. During mitosis, cytokinetic nodes with Mid1p and all of the type 2 node markers incorporate into the contractile ring, whereas type 1 nodes with Cdr1p and Cdr2p follow the separating nuclei before dispersing into the cytoplasm, dependent on septation initiation network signaling. The two types of interphase nodes follow parallel branches of the pathway to prepare nodes for cytokinesis.

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.

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