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 Proper timing of cytokinesis is regulated by Schizosaccharomyces pombe Etd1

2009 ◽  
Vol 186 (5) ◽  
pp. 739-753 ◽  
Author(s):  
Juan Carlos García-Cortés ◽  
Dannel McCollum
Keyword(s):  
Fission Yeast ◽  
Spindle Pole Body ◽  
Spindle Pole ◽  
Yeast Protein ◽  
Late Anaphase ◽  
Pole Body ◽  
Spindle Elongation ◽  
Cell Asymmetry ◽  
Guanosine Triphosphatase ◽  
Asymmetric Activation

Cytokinesis must be initiated only after chromosomes have been segregated in anaphase and must be terminated once cleavage is completed. We show that the fission yeast protein Etd1 plays a central role in both of these processes. Etd1 activates the guanosine triphosphatase (GTPase) Spg1 to trigger signaling through the septum initiation network (SIN) pathway and onset of cytokinesis. Spg1 is activated in late anaphase when spindle elongation brings spindle pole body (SPB)–localized Spg1 into proximity with its activator Etd1 at cell tips, ensuring that cytokinesis is only initiated when the spindle is fully elongated. Spg1 is active at just one of the two SPBs during cytokinesis. When the actomyosin ring finishes constriction, the SIN triggers disappearance of Etd1 from the half of the cell with active Spg1, which then triggers Spg1 inactivation. Asymmetric activation of Spg1 is crucial for timely inactivation of the SIN. Together, these results suggest a mechanism whereby cell asymmetry is used to monitor cytoplasmic partitioning to turn off cytokinesis signaling.

The spindle pole body plays a key role in controlling mitotic commitment in the fission yeast Schizosaccharomyces pombe

2008 ◽  
Vol 36 (5) ◽  
pp. 1097-1101 ◽  
Author(s):  
Iain M. Hagan
Keyword(s):  
Protein Kinase ◽  
Fission Yeast ◽  
Critical Role ◽  
Spindle Pole Body ◽  
Growth Control ◽  
Spindle Pole ◽  
Mitogen Activated Protein Kinase ◽  
Polo Kinase ◽  
Pole Body ◽  
Mitogen Activated Protein

Commitment to mitosis is regulated by a conserved protein kinase complex called MPF (mitosis-promoting factor). MPF activation triggers a positive-feedback loop that further promotes the activity of its activating phosphatase Cdc25 and is assumed to down-regulate the MPF-inhibitory kinase Wee1. Four protein kinases contribute to this amplification loop: MPF itself, Polo kinase, MAPK (mitogen-activated protein kinase) and Greatwall kinase. The fission yeast SPB (spindle pole body) component Cut12 plays a critical role in modulating mitotic commitment. In this review, I discuss the relationship between Cut12 and the fission yeast Polo kinase Plo1 in mitotic control. These results indicate that commitment to mitosis is co-ordinated by control networks on the spindle pole. I then describe how the Cut12/Plo1 control network links growth control signalling from TOR (target of rapamycin) and MAPK networks to the activation of MPF to regulate the timing of cell division.

scholarly journals The fission yeast septation initiation network (SIN) kinase, Sid2, is required for SIN asymmetry and regulates the SIN scaffold, Cdc11

2012 ◽  
Vol 23 (9) ◽  
pp. 1636-1645 ◽  
Author(s):  
Anna Feoktistova ◽  
Jennifer Morrell-Falvey ◽  
Jun-Song Chen ◽  
N. Sadananda Singh ◽  
Mohan K. Balasubramanian ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Spindle Pole Body ◽  
Spindle Pole ◽  
Asymmetric Distribution ◽  
Kinase Cascade ◽  
Septation Initiation Network ◽  
Ring Constriction ◽  
Signaling Components ◽  
Protein Kinase Cascade

The Schizosaccharomyces pombe septation initiation network (SIN) is an Spg1-GTPase–mediated protein kinase cascade that triggers actomyosin ring constriction, septation, and cell division. The SIN is assembled at the spindle pole body (SPB) on the scaffold proteins Cdc11 and Sid4, with Cdc11 binding directly to SIN signaling components. Proficient SIN activity requires the asymmetric distribution of its signaling components to one of the two SPBs during anaphase, and Cdc11 hyperphosphorylation correlates with proficient SIN activity. In this paper, we show that the last protein kinase in the signaling cascade, Sid2, feeds back to phosphorylate Cdc11 during mitosis. The characterization of Cdc11 phosphomutants provides evidence that Sid2-mediated Cdc11 phosphorylation promotes the association of the SIN kinase, Cdc7, with the SPB and maximum SIN signaling during anaphase. We also show that Sid2 is crucial for the establishment of SIN asymmetry, indicating a positive-feedback loop is an important element of the SIN.

Counteracting Regulation of Chromatin Remodeling at a Fission Yeast cAMP Responsive Element-Related Recombination Hotspot by Stress-Activated Protein Kinase, cAMP-Dependent Kinase and Meiosis Regulators

Genetics ◽  
2001 ◽  
Vol 159 (4) ◽  
pp. 1467-1478 ◽  
Author(s):  
Ken-ichi Mizuno ◽  
Tomoko Hasemi ◽  
Toshiharu Ubukata ◽  
Takatomi Yamada ◽  
Elisabeth Lehmann ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Fission Yeast ◽  
Chromatin Remodeling ◽  
Meiotic Recombination ◽  
Cellular Differentiation ◽  
Dependent Protein Kinase ◽  
Physiological Factors ◽  
Dependent Protein ◽  
Responsive Element ◽  
Pka Pathway

AbstractIn fission yeast, an ATF/CREB-family transcription factor Atf1-Pcr1 plays important roles in the activation of early meiotic processes via the stress-activated protein kinase (SAPK) and the cAMP-dependent protein kinase (PKA) pathways. In addition, Atf1-Pcr1 binds to a cAMP responsive element (CRE)-like sequence at the site of the ade6-M26 mutation, which results in local enhancement of meiotic recombination and chromatin remodeling. Here we studied the roles of meiosis-inducing signal transduction pathways in M26 chromatin remodeling. Chromatin analysis revealed that persistent activation of PKA in meiosis inhibited M26 chromatin remodeling, suggesting that the PKA pathway represses M26 chromatin remodeling. The SAPK pathway activated M26 chromatin remodeling, since mutants lacking a component of this pathway, the Wis1 or Spc1/Sty1 kinases, had no M26 chromatin remodeling. M26 chromatin remodeling also required the meiosis regulators Mei2 and Mei3 but not the subsequently acting regulators Sme2 and Mei4, suggesting that induction of M26 chromatin remodeling needs meiosis-inducing signals before premeiotic DNA replication. Similar meiotic chromatin remodeling occurred meiotically around natural M26 heptamer sequences. These results demonstrate the coordinated action of genetic and physiological factors required to remodel chromatin in preparation for high levels of meiotic recombination and eukaryotic cellular differentiation.

Identification of sds21 in fission yeast in an inhibitor-resistant high molecular mass protein phosphatase-1 complex

1999 ◽  
Vol 77 (6) ◽  
pp. 551-558 ◽  
Author(s):  
John F Dawson ◽  
Charles FB Holmes
Keyword(s):  
Protein Kinase ◽  
Molecular Mass ◽  
Fission Yeast ◽  
Phosphatase Activity ◽  
Protein Phosphatase ◽  
High Molecular Mass ◽  
Protein Phosphatase 1 ◽  
Dependent Protein Kinase ◽  
Dependent Protein

While characterizing the type-1 protein phosphatases sds21 and dis2 in fission yeast (Schizosaccharomyces pombe) a novel high molecular mass protein was identified with serine/threonine phosphatase activity (referred to as PP-R) that was resistant to a panel of characteristic inhibitors of protein phosphatases. Purification of the native sds21 catalytic isoform of protein phosphatase-1 (PP-1) from an S. pombe knockout strain lacking dis2 (Δdis2) resulted predominantly in identification of PP-R. To test the hypothesis that the catalytic activity of PP-R comprised sds21, a parallel purification was performed of PP-1 activity from an S. pombe knockout strain lacking sds21 (Δsds21). Both Δsds21 and Δdis2 strains exhibited similar protein phosphatase activity profiles as determined by DEAE-sepharose, Mono-Q and Superdex gel filtration chromatography. However, the peak of protein phosphatase activity from Δsds21 S. pombe that co-migrated with PP-R from Δdis2 S. pombe exhibited the sensitivity to a panel of inhibitors that was characteristic of a type-1 protein phosphatase. These data suggest that the catalytic subunit of PP-R comprises sds21 and that the resistance to inhibitors may originate from structural differences between dis2 and sds21 isoforms. A key structural feature present in sds21, but lacking in dis2, is a classical phosphorylation consensus sequence surrounding serine-145 of sds21. The previous hypothesis was that PP-1 activity among several lower eukaryotes may be regulated directly by cAMP-dependent protein kinase (PKA) phosphorylation. However, this study demonstrated that recombinant sds21 is not a target for PKA in vitro. The constrained configuration of the putative PKA site on the PP-1 holoenzyme may restrict its ability to be targeted by PKA.Key words: cAMP-dependent protein kinase, protein phosphatase-1, sds21, dis2, G-subunit, microcystin-LR, okadaic acid, S. pombe.

scholarly journals Regulation of the Subcellular Localization of Cyclic AMP-Dependent Protein Kinase in Response to Physiological Stresses and Sexual Differentiation in the Fission Yeast Schizosaccharomyces pombe

2008 ◽  
Vol 7 (9) ◽  
pp. 1450-1459 ◽  
Author(s):  
Yasuhiro Matsuo ◽  
Brittney McInnis ◽  
Stevan Marcus
Keyword(s):  
Protein Kinase ◽  
Cyclic Amp ◽  
Adenylate Cyclase ◽  
Subcellular Localization ◽  
Stationary Phase ◽  
Fission Yeast ◽  
Sexual Differentiation ◽  
Phase Growth ◽  
Dependent Protein Kinase ◽  
Dependent Protein

ABSTRACT We describe regulation of the subcellular localization of cyclic AMP (cAMP)-dependent protein kinase (PKA) regulatory (Cgs1p) and catalytic (Pka1p) subunits in the fission yeast Schizosaccharomyces pombe in response to physiological stresses and during sexual differentiation as determined by fluorescence microscopy of the Cgs1-green fluorescent protein (GFP) and Pka1-GFP fusion proteins, respectively. In wild-type S. pombe cells cultured to log phase under normal growth conditions, Cgs1p and Pka1p are concentrated in the nucleus and more diffusely present in the cytoplasm. Nuclear localization of both proteins is dependent on cAMP, since in cells lacking adenylate cyclase they are detectable only in the cytoplasm. In cells lacking Cgs1p or both Cgs1p and adenylate cyclase, Pka1p is concentrated in the nucleus, demonstrating a role for Cgs1p in the nuclear exclusion of Pka1p. Nuclear-cytoplasmic redistribution of Cgs1p and Pka1p is triggered by growth in glucose-limited or hyperosmotic media and in response to stationary-phase growth. In addition, both proteins are excluded from the nucleus in mating cells undergoing karyogamy and subsequently concentrated in postmeiotic spores. Cgs1p is required for subcellular redistribution of Pka1p induced by growth in glucose-limited and hyperosmotic media and during karyogamy but is not required for Pka1p redistribution triggered by stationary-phase growth or for the enrichment of Pka1p in spores. Our results demonstrate that PKA localization is regulated by cAMP and regulatory subunit-dependent and -independent mechanisms in S. pombe.

Sign in / Sign up

Export Citation Format

Share Document