Specific detection of fission yeast primary septum reveals septum and cleavage furrow ingression during early anaphase independent of mitosis completion

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.

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Role of Inn1 and its interactions with Hof1 and Cyk3 in promoting cleavage furrow and septum formation in S. cerevisiae

The Journal of Cell Biology ◽

10.1083/jcb.200903125 ◽

2009 ◽

Vol 185 (6) ◽

pp. 995-1012 ◽

Cited By ~ 68

Author(s):

Ryuichi Nishihama ◽

Jennifer H. Schreiter ◽

Masayuki Onishi ◽

Elizabeth A. Vallen ◽

Julia Hanna ◽

...

Keyword(s):

Saccharomyces Cerevisiae ◽

Mitotic Exit ◽

Chitin Synthase ◽

Cleavage Furrow ◽

Sh3 Domains ◽

C2 Domains ◽

Division Site ◽

Primary Septum ◽

N Terminus

Cytokinesis requires coordination of actomyosin ring (AMR) contraction with rearrangements of the plasma membrane and extracellular matrix. In Saccharomyces cerevisiae, new membrane, the chitin synthase Chs2 (which forms the primary septum [PS]), and the protein Inn1 are all delivered to the division site upon mitotic exit even when the AMR is absent. Inn1 is essential for PS formation but not for Chs2 localization. The Inn1 C-terminal region is necessary for localization, and distinct PXXP motifs in this region mediate functionally important interactions with SH3 domains in the cytokinesis proteins Hof1 (an F-BAR protein) and Cyk3 (whose overexpression can restore PS formation in inn1Δ cells). The Inn1 N terminus resembles C2 domains but does not appear to bind phospholipids; nonetheless, when overexpressed or fused to Hof1, it can provide Inn1 function even in the absence of the AMR. Thus, Inn1 and Cyk3 appear to cooperate in activating Chs2 for PS formation, which allows coordination of AMR contraction with ingression of the cleavage furrow.

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The (1,3)β-d-glucan synthase subunit Bgs1p is responsible for the fission yeast primary septum formation

Molecular Microbiology ◽

10.1111/j.1365-2958.2007.05784.x ◽

2007 ◽

Vol 65 (1) ◽

pp. 201-217 ◽

Cited By ~ 71

Author(s):

Juan Carlos G. Cortés ◽

Mami Konomi ◽

Ivone M. Martins ◽

Javier Muñoz ◽

M. Belén Moreno ◽

...

Keyword(s):

Fission Yeast ◽

Glucan Synthase ◽

Septum Formation ◽

Primary Septum

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Analysis of the distribution of the INCENPs throughout mitosis reveals the existence of a pathway of structural changes in the chromosomes during metaphase and early events in cleavage furrow formation

Journal of Cell Science ◽

10.1242/jcs.98.4.443 ◽

1991 ◽

Vol 98 (4) ◽

pp. 443-461 ◽

Cited By ~ 1

Author(s):

W.C. Earnshaw ◽

C.A. Cooke

Keyword(s):

Structural Changes ◽

Metaphase Plate ◽

Maximum Diameter ◽

Cell Cortex ◽

Cleavage Furrow ◽

Intracellular Location ◽

Chromosomal Passenger ◽

Early Anaphase ◽

Chromosomal Passenger Proteins ◽

Passenger Proteins

The INCENPs are two polypeptides of 135 × 10(3) and 150 × 10(3) Mr that enter mitosis as tightly bound chromosomal proteins, but subsequently leave the chromosomes altogether and become associated with the central spindle and cell cortex at the contractile ring. In the experiments reported here we have used confocal microscopy and immunoelectron microscopy to provide a detailed picture of the intracellular location of these proteins during mitosis. The experiments have not only revealed a number of new details concerning the properties of the INCENPs in mitosis, but have revealed a number of novel aspects of the mitotic process itself. The first of these is the existence of a sequential pathway of structural changes in the chromosomes that occurs during metaphase. This pathway is revealed by the existence of four distinct INCENP staining patterns in mitotic cells. In ‘early’ and ‘early/mid’ metaphase, the INCENPs gradually become concentrated at the centromeres, forming a ring at the center of the metaphase plate. During ‘mid/late’ metaphase they exit from the chromosomes, so that by late metaphase they are found solely in streaks that traverse the plate parallel to the spindle axis. The streaks probably correspond to INCENPs closely associated with microtubule bundles, perhaps as part of the stem body material. Examination of transverse optical sections of the spindle interzone during early anaphase reveals an unexpectedly high degree of order. The INCENP antigens are localized on fibers that are organized into a hollow ring 8 microns in diameter and approximately 4 microns beneath the cell cortex. Measurement of cellular dimensions in the confocal microscope reveals that the maximum diameter of early anaphase cells lies across the spindle equator, so that when the cleavage furrow forms, it does so around the maximum circumference of the cell. During anaphase, a subpopulation of the INCENP antigen becomes localized to the cortex where the furrow will subsequently form. This occurs prior to any other evidence of furrowing. Thus, binding of the INCENPs to this region may represent an early step in furrow formation. Together, these results suggest that the INCENPs may represent a new class of ‘chromosomal passenger’ proteins that are carried to the spindle equator by the chromosomes and subsequently perform a cytoskeletal role following their release from the chromosomes at the metaphase:anaphase transition.

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

Molecular Biology of the Cell ◽

10.1091/mbc.e18-04-0270 ◽

2019 ◽

Vol 30 (15) ◽

pp. 1791-1804 ◽

Cited By ~ 4

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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Role of the α-Glucanase Agn1p in Fission-Yeast Cell Separation

Molecular Biology of the Cell ◽

10.1091/mbc.e04-04-0319 ◽

2004 ◽

Vol 15 (8) ◽

pp. 3903-3914 ◽

Cited By ~ 89

Author(s):

Nick Dekker ◽

Dave Speijer ◽

Christian H. Grün ◽

Marlene van den Berg ◽

Annett de Haan ◽

...

Keyword(s):

Cell Division ◽

Fission Yeast ◽

Cell Separation ◽

Wall Material ◽

Dependent Manner ◽

Cellular Functions ◽

Daughter Cells ◽

Primary Septum ◽

Cycle Dependent ◽

Division Cell

Cell division in the fission yeast Schizosaccharomyces pombe yields two equal-sized daughter cells. Medial fission is achieved by deposition of a primary septum flanked by two secondary septa within the dividing cell. During the final step of cell division, cell separation, the primary septum is hydrolyzed by an endo-(1,3)-β-glucanase, Eng1p. We reasoned that the cell wall material surrounding the septum, referred to here as the septum edging, also must be hydrolyzed before full separation of the daughter cells can occur. Because the septum edging contains (1,3)-α-glucan, we investigated the cellular functions of the putative (1,3)-α-glucanases Agn1p and Agn2p. Whereas agn2 deletion results in a defect in endolysis of the ascus wall, deletion of agn1 leads to clumped cells that remained attached to each other by septum-edging material. Purified Agn1p hydrolyzes (1,3)-α-glucan predominantly into pentasaccharides, indicating an endo-catalytic mode of hydrolysis. Furthermore, we show that the transcription factors Sep1p and Ace2p regulate both eng1 and agn1 expression in a cell cycle-dependent manner. We propose that Agn1p acts in concert with Eng1p to achieve efficient cell separation, thereby exposing the secondary septa as the new ends of the daughter cells.

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Cdc42 promotes Bgs1 recruitment for septum synthesis and glucanase localization for cell separation during cytokinesis in fission yeast

10.1101/754390 ◽

2019 ◽

Cited By ~ 1

Author(s):

Udo N. Onwubiko ◽

Julie Robinson ◽

Rose Albu Mustaf ◽

Maitreyi E. Das

Keyword(s):

Fission Yeast ◽

Membrane Trafficking ◽

Cell Separation ◽

Nucleotide Exchange ◽

Timely Initiation ◽

Division Site ◽

Guanine Nucleotide Exchange ◽

Nucleotide Exchange Factors ◽

Primary Septum ◽

Ring Constriction

AbstractCytokinesis in fission yeast involves actomyosin ring constriction concurrent to septum synthesis followed by septum digestion resulting in cell separation. A recent report indicates that endocytosis is required for septum synthesis and cell separation. The conserved GTPase Cdc42 is required for membrane trafficking and promotes endocytosis. Cdc42 is activated by Guanine nucleotide exchange factors (GEFs). Cdc42 GEFs have been shown to promote timely initiation of septum synthesis and proper septum morphology. Here we show that Cdc42 promotes the recruitment of the major primary septum synthesizing enzyme Bgs1 and consequent ring constriction. Cdc42 is also required for proper localization of the septum digesting glucanases at the division site. Thus, Cdc42 is required to promote multiple steps during cytokinesis.

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Role of the Hof1–Cyk3 interaction in cleavage-furrow ingression and primary-septum formation during yeast cytokinesis

Molecular Biology of the Cell ◽

10.1091/mbc.e17-04-0227 ◽

2018 ◽

Vol 29 (5) ◽

pp. 597-609 ◽

Cited By ~ 10

Author(s):

Meng Wang ◽

Ryuichi Nishihama ◽

Masayuki Onishi ◽

John R. Pringle

Keyword(s):

Saccharomyces Cerevisiae ◽

Functional Significance ◽

Normal Rate ◽

Cleavage Furrow ◽

Type Ii ◽

Septum Formation ◽

Primary Septum ◽

Direct Binding ◽

Type Ii Myosin

In Saccharomyces cerevisiae, it is well established that Hof1, Cyk3, and Inn1 contribute to septum formation and cytokinesis. Because hof1∆ and cyk3∆ single mutants have relatively mild defects but hof1∆ cyk3∆ double mutants are nearly dead, it has been hypothesized that these proteins contribute to parallel pathways. However, there is also evidence that they interact physically. In this study, we examined this interaction and its functional significance in detail. Our data indicate that the interaction 1) is mediated by a direct binding of the Hof1 SH3 domain to a proline-rich motif in Cyk3; 2) occurs specifically at the time of cytokinesis but is independent of the (hyper)phosphorylation of both proteins that occurs at about the same time; 3) is dispensable for the normal localization of both proteins; 4) is essential for normal primary-septum formation and a normal rate of cleavage-furrow ingression; and 5) becomes critical for growth when either Inn1 or the type II myosin Myo1 (a key component of the contractile actomyosin ring) is absent. The similarity in phenotype between cyk3∆ mutants and mutants specifically lacking the Hof1–Cyk3 interaction suggests that the interaction is particularly important for Cyk3 function, but it may be important for Hof1 function as well.

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Plo1 Kinase Recruitment to the Spindle Pole Body and Its Role in Cell Division inSchizosaccharomyces pombe

Molecular Biology of the Cell ◽

10.1091/mbc.10.8.2771 ◽

1999 ◽

Vol 10 (8) ◽

pp. 2771-2785 ◽

Cited By ~ 90

Author(s):

Daniel P. Mulvihill ◽

Janni Petersen ◽

Hiroyuki Ohkura ◽

David M. Glover ◽

Iain M. Hagan

Keyword(s):

Cell Division ◽

Fission Yeast ◽

Spindle Pole Body ◽

Spindle Pole ◽

Multiple Roles ◽

Anaphase Promoting Complex ◽

Pole Body ◽

Early Anaphase ◽

Anaphase B ◽

Mitotic Event

Polo kinases execute multiple roles during cell division. The fission yeast polo related kinase Plo1 is required to assemble the mitotic spindle, the prophase actin ring that predicts the site for cytokinesis and for septation after the completion of mitosis ( Ohkuraet al., 1995 ; Bahler et al., 1998 ). We show that Plo1 associates with the mitotic but not interphase spindle pole body (SPB). SPB association of Plo1 is the earliest fission yeast mitotic event recorded to date. SPB association is strong from mitotic commitment to early anaphase B, after which the Plo1 signal becomes very weak and finally disappears upon spindle breakdown. SPB association of Plo1 requires mitosis-promoting factor (MPF) activity, whereas its disassociation requires the activity of the anaphase-promoting complex. The stf1.1 mutation bypasses the usual requirement for the MPF activator Cdc25 ( Hudson et al., 1990 ). Significantly, Plo1 associates inappropriately with the interphase SPB of stf1.1 cells. These data are consistent with the emerging theme from many systems that polo kinases participate in the regulation of MPF to determine the timing of commitment to mitosis and may indicate that pole association is a key aspect of Plo1 function. Plo1 does not associate with the SPB when septation is inappropriately driven by deregulation of the Spg1 pathway and remains SPB associated if septation occurs in the presence of a spindle. Thus, neither Plo1 recruitment to nor its departure from the SPB are required for septation; however, overexpression ofplo1+activates the Spg1 pathway and causes transient Cdc7 recruitment to the SPB and multiple rounds of septation.

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