scholarly journals Effect of the Pheromone-Responsive Gα and Phosphatase Proteins of Saccharomyces cerevisiae on the Subcellular Localization of the Fus3 Mitogen-Activated Protein Kinase

2003 ◽  
Vol 23 (4) ◽  
pp. 1135-1150 ◽  
Author(s):  
Ernest Blackwell ◽  
Izabel M. Halatek ◽  
Hye-Jin N. Kim ◽  
Alexis T. Ellicott ◽  
Andrey A. Obukhov ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Protein Kinase ◽  
Fluorescent Protein ◽  
Nucleocytoplasmic Transport ◽  
Mitogen Activated Protein Kinase ◽  
Mutant Form ◽  
Relative Level ◽  
Mitogen Activated Protein ◽  
Mating Signal ◽  
Green Fluorescent

ABSTRACT The mating-specific Gα protein of Saccharomyces cerevisiae, Gpa1, stimulates adaptation to pheromone by a mechanism independent of Gβγ sequestration. Genetic evidence suggests that Gpa1 targets the Fus3 mitogen-activated protein kinase, and it has recently been shown that the two proteins interact in cells responding to pheromone. To test the possibility that Gpa1 downregulates the mating signal by affecting the localization of Fus3, we created a Fus3-green fluorescent protein (GFP) fusion protein. In vegetative cells, Fus3-GFP was found in both the cytoplasm and the nucleus. Pheromone stimulated a measurable increase in the ratio of nuclear to cytoplasmic Fus3-GFP. In contrast, the relative level of nuclear Fus3-GFP decreased as cells recovered from pheromone arrest and did not increase when cells adapted to chronic stimulus were challenged again. Accumulation of Fus3-GFP in the nuclei of stimulated cells was also inhibited by overexpression of either wild-type Gpa1, the E364K hyperadaptive mutant form of Gpa1, or the Msg5 dually specific phosphatase. The effects of Gpa1 and Msg5 on Fus3 are partially interdependent. In a genetic screen for adaptive defective mutants, a nonsense allele of the nucleocytoplasmic transport receptor, Kap104, was identified. Truncation of the Kap104 cargo-binding domain blocked the effect of both Gpa1E364K and Msg5 on Fus3-GFP localization. Based on these results, we propose that Gpa1 and Msg5 work in concert to downregulate the mating signal and that they do so by inhibiting the pheromone-induced increase of Fus3 in the nucleus. Kap104 is required for the Gα/phosphatase-mediated effect on Fus3 localization.

scholarly journals Phosphoprotein Enriched in Astrocytes-15 kDa Expression Inhibits Astrocyte Migration by a Protein Kinase Cδ-dependent Mechanism

2006 ◽  
Vol 17 (12) ◽  
pp. 5141-5152 ◽  
Author(s):  
François Renault-Mihara ◽  
Frédéric Beuvon ◽  
Xavier Iturrioz ◽  
Brigitte Canton ◽  
Sophie De Bouard ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Fluorescent Protein ◽  
Constitutive Expression ◽  
Mitogen Activated Protein Kinase ◽  
Wild Type ◽  
Bryostatin 1 ◽  
Calcium Calmodulin Dependent ◽  
Mitogen Activated Protein ◽  
Green Fluorescent

Phosphoprotein enriched in astrocytes-15 kDa (PEA-15), a phosphoprotein enriched in astrocytes, inhibits both apoptosis and proliferation in normal and cancerous cells. Here, analysis of PEA-15 expression in glioblastoma organotypic cultures revealed low levels of PEA-15 in tumor cells migrating away from the explants, regardless of the expression levels in the originating explants. Because glioblastomas are highly invasive primary brain tumors that can originate from astrocytes, we explored the involvement of PEA-15 in the control of astrocyte migration. PEA-15−/− astrocytes presented an enhanced motility in vitro compared with their wild-type counterparts. Accordingly, NIH-3T3 cells transfected by green fluorescent protein-PEA-15 displayed a reduced migration. Reexpression of PEA-15 restored PEA-15−/− astrocyte motility to wild-type levels. Pharmacological manipulations excluded a participation of extracellular signal-regulated kinase/mitogen-activated protein kinase, phosphatidylinositol 3-kinase/Akt, and calcium/calmodulin-dependent protein kinase II in this effect of PEA-15. In contrast, treatment by bisindolylmaleimide, Gö6976, and rottlerin, and chronic application of phorbol 12-myristate 13-acetate and/or bryostatin-1 indicated that PKCδ mediated PEA-15 inhibition of astrocyte migration. PEA-15−/− astrocytes constitutively expressed a 40-kDa form of PKCδ that was down-regulated upon PEA-15 reexpression. Together, these data reveal a new function for PEA-15 in the inhibitory control of astrocyte motility through a PKCδ-dependent pathway involving the constitutive expression of a catalytic fragment of PKCδ.

scholarly journals Bax translocates to mitochondria of heart cells during simulated ischaemia: involvement of AMP-activated and p38 mitogen-activated protein kinases

2006 ◽  
Vol 395 (1) ◽  
pp. 57-64 ◽  
Author(s):  
Michela Capano ◽  
Martin Crompton
Keyword(s):  
Protein Kinase ◽  
Protein Kinases ◽  
P38 Mapk ◽  
Fluorescent Protein ◽  
Mitogen Activated Protein Kinase ◽  
Heart Cells ◽  
Intermembrane Space ◽  
Neonatal Cardiomyocytes ◽  
Mitogen Activated Protein ◽  
Green Fluorescent

The cytosolic protein Bax plays a key role in apoptosis by migrating to mitochondria and releasing proapoptotic proteins from the mitochondrial intermembrane space. The present study investigates the movement of Bax in isolated rat neonatal cardiomyocytes subjected to simulated ischaemia (minus glucose, plus cyanide), using green fluorescent protein-tagged Bax as a means of imaging Bax movements. Simulated ischaemia induced Bax translocation from the cytosol to mitochondria, commencing within 20 min of simulated ischaemia and progressing for several hours. Under the same conditions, there was an increase in the active, phosphorylated forms of p38 MAPK (mitogen-activated protein kinase) and AMPK (AMP-activated protein kinase). The AMPK activators AICAR (5-aminoimidazole-4-carboxamide ribonucleoside) and metformin also stimulated Bax translocation. Inhibition of p38 MAPK with SB203580 attenuated the phosphorylation of the downstream substrates, MAPK-activated protein kinases 2 and 3, but not that of the upstream MAPK kinase 3, nor of AMPK. Under all conditions (ischaemia, AICAR and metformin), SB203580 blocked Bax translocation completely. It is concluded that Bax translocation to mitochondria is an early step in ischaemia and that it occurs in response to activation of p38 MAPK downstream of AMPK.

Interaction of the Repressors Nrg1 and Nrg2 With the Snf1 Protein Kinase in Saccharomyces cerevisiae

Genetics ◽  
2001 ◽  
Vol 158 (2) ◽  
pp. 563-572 ◽  
Author(s):  
Valmik K Vyas ◽  
Sergei Kuchin ◽  
Marian Carlson
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Protein Kinase ◽  
Hybrid System ◽  
Fluorescent Protein ◽  
Zinc Finger Protein ◽  
Glucose Repression ◽  
Snf1 Kinase ◽  
Cell Extracts ◽  
Green Fluorescent ◽  
Two Hybrid

Abstract The Snf1 protein kinase is essential for the transcription of glucose-repressed genes in Saccharomyces cerevisiae. We identified Nrg2 as a protein that interacts with Snf1 in the two-hybrid system. Nrg2 is a C2H2 zinc-finger protein that is homologous to Nrg1, a repressor of the glucose- and Snf1-regulated STA1 (glucoamylase) gene. Snf1 also interacts with Nrg1 in the two-hybrid system and co-immunoprecipitates with both Nrg1 and Nrg2 from cell extracts. A LexA fusion to Nrg2 represses transcription from a promoter containing LexA binding sites, indicating that Nrg2 also functions as a repressor. An Nrg1 fusion to green fluorescent protein is localized to the nucleus, and this localization is not regulated by carbon source. Finally, we show that VP16 fusions to Nrg1 and Nrg2 allow low-level expression of SUC2 in glucose-grown cells, and we present evidence that Nrg1 and Nrg2 contribute to glucose repression of the DOG2 gene. These results suggest that Nrg1 and Nrg2 are direct or indirect targets of the Snf1 kinase and function in glucose repression of a subset of Snf1-regulated genes.

scholarly journals Both Binding and Activation of p38 Mitogen-Activated Protein Kinase (MAPK) Play Essential Roles in Regulation of the Nucleocytoplasmic Distribution of MAPK-Activated Protein Kinase 5 by Cellular Stress

2002 ◽  
Vol 22 (20) ◽  
pp. 6931-6945 ◽  
Author(s):  
Ole Morten Seternes ◽  
Bjarne Johansen ◽  
Beate Hegge ◽  
Mona Johannessen ◽  
Stephen M. Keyse ◽  
...  
Keyword(s):  
Protein Kinase ◽  
P38 Mapk ◽  
Nuclear Export ◽  
Fluorescent Protein ◽  
Mapk Pathway ◽  
Nuclear Export Signal ◽  
Mitogen Activated Protein Kinase ◽  
Protein Fusion ◽  
Translational Machinery ◽  
Mitogen Activated Protein

ABSTRACT The p38 mitogen-activated protein kinase (MAPK) pathway is an important mediator of cellular responses to environmental stress. Targets of p38 include transcription factors, components of the translational machinery, and downstream serine/threonine kinases, including MAPK-activated protein kinase 5 (MK5). Here we have used enhanced green fluorescent protein fusion proteins to analyze the subcellular localization of MK5. Although this protein is predominantly nuclear in unstimulated cells, MK5 shuttles between the nucleus and the cytoplasm. Furthermore, we have shown that the C-terminal domain of MK5 contains both a functional nuclear localization signal (NLS) and a leucine-rich nuclear export signal (NES), indicating that the subcellular distribution of this kinase reflects the relative activities of these two signals. In support of this, we have shown that stress-induced activation of the p38 MAPK stimulates the chromosomal region maintenance 1 protein-dependent nuclear export of MK5. This is regulated by both binding of p38 MAPK to MK5, which masks the functional NLS, and stress-induced phosphorylation of MK5 by p38 MAPK, which either activates or unmasks the NES. These properties may define the ability of MK5 to differentially phosphorylate both nuclear and cytoplasmic targets or alternatively reflect a mechanism whereby signals initiated by activation of MK5 in the nucleus may be transmitted to the cytoplasm.

scholarly journals Saccharomyces cerevisiae and Caffeine Implications on the Eukaryotic Cell

Nutrients ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 2440
Author(s):  
Lavinia Liliana Ruta ◽  
Ileana Cornelia Farcasanu
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Protein Kinase ◽  
Molecular Mechanisms ◽  
Eukaryotic Cell ◽  
Pleiotropic Effect ◽  
Mitogen Activated Protein Kinase ◽  
Active Principle ◽  
Cell Integrity ◽  
Tor Signaling ◽  
Mitogen Activated Protein

Caffeine–a methylxanthine analogue of the purine bases adenine and guanine–is by far the most consumed neuro-stimulant, being the active principle of widely consumed beverages such as coffee, tea, hot chocolate, and cola. While the best-known action of caffeine is to prevent sleepiness by blocking the adenosine receptors, caffeine exerts a pleiotropic effect on cells, which lead to the activation or inhibition of various cell integrity pathways. The aim of this review is to present the main studies set to investigate the effects of caffeine on cells using the model eukaryotic microorganism Saccharomyces cerevisiae, highlighting the caffeine synergy with external cell stressors, such as irradiation or exposure to various chemical hazards, including cigarette smoke or chemical carcinogens. The review also focuses on the importance of caffeine-related yeast phenotypes used to resolve molecular mechanisms involved in cell signaling through conserved pathways, such as target of rapamycin (TOR) signaling, Pkc1-Mpk1 mitogen activated protein kinase (MAPK) cascade, or Ras/cAMP protein kinase A (PKA) pathway.

scholarly journals Internalization of gonadotropin-releasing hormone receptors (GnRHRs): does arrestin binding to the C-terminal tail target GnRHRs for dynamin-dependent internalization?

2005 ◽  
Vol 35 (1) ◽  
pp. 177-189 ◽  
Author(s):  
James N Hislop ◽  
Christopher J Caunt ◽  
Kathleen R Sedgley ◽  
Eammon Kelly ◽  
Stuart Mundell ◽  
...  
Keyword(s):  
Hormone Receptors ◽  
Fluorescent Protein ◽  
Protein Translocation ◽  
Gonadotropin Releasing Hormone ◽  
Mitogen Activated Protein Kinase ◽  
Type I ◽  
Releasing Hormone ◽  
Extracellular Signal ◽  
Mitogen Activated Protein ◽  
Green Fluorescent

Activation of seven-transmembrane receptors is typically followed by desensitization and arrestin-dependent internalization via vesicles that are pinched off by a dynamin collar. Arrestins also scaffold Src, which mediates dynamin-dependent internalization of β2-adrenergic receptors. Type I mammalian gonadotropin-releasing hormone receptors (GnRHRs) do not rapidly desensitize or internalize (characteristics attributed to their unique lack of C-terminal tails) whereas non-mammalian GnRHRs (that have C-terminal tails) are rapidly internalized and desensitized. Moreover, internalization of Xenopus (X) GnRHRs is dynamin-dependent whereas that of human (h) GnRHRs is not, raising the possibility that binding of arrestin to the C-terminal tails of GnRHRs targets them to the dynamin-dependent internalization pathway. To test this we have compared wild-type GnRHRs with chimeric receptors (XGnRHR C-terminal tail added to the hGnRHR alone (h.XtGnRHR) or with exchange of the third intracellular loops (h.Xl.XtGnRHR)). We show that adding the XGnRHR C-terminal tail facilitates arrestin- and dynamin-dependent internalization as well as arrestin/green fluorescent protein translocation, but Src (or mitogen-activated protein kinase/extracellular-signal-regulated kinase kinase) inhibition does not slow internalization, and h.XtGnRHR internalization is slower than that of the hGnRHR. Moreover, arrestin expression increased XGnRHR internalization even when dynamin was inhibited and h.Xl.XtGnRHR underwent rapid arrestin-dependent internalization without signaling to Gq/11. Thus, although the C-terminal tail can direct GnRHRs for arrestin- and dynamin-dependent internalization, this effect is not dependent on Src activation and arrestin can also facilitate dynamin-independent internalization.

scholarly journals A Yeast STE11 Homologue CoMEKK1 Is Essential for Pathogenesis-Related Morphogenesis in Colletotrichum orbiculare

2010 ◽  
Vol 23 (12) ◽  
pp. 1563-1572 ◽  
Author(s):  
Ayumu Sakaguchi ◽  
Gento Tsuji ◽  
Yasuyuki Kubo
Keyword(s):  
Signal Transduction ◽  
Fluorescent Protein ◽  
Intracellular Localization ◽  
Active Form ◽  
Hyphal Growth ◽  
Mitogen Activated Protein Kinase ◽  
Colletotrichum Orbiculare ◽  
Pathogenesis Related ◽  
Mitogen Activated Protein ◽  
Green Fluorescent

Several signal transduction pathways, including mitogen-activated protein kinase (MAPK) pathways, are involved in appressorium development in Colletotrichum orbiculare, the causal agent of cucumber anthracnose disease. In this study, CoMEKK1, a yeast MAPK kinases (MAPKK) kinase STE11 homolog, was identified as a disrupted gene in an Agrobacterium tumefaciens-mediated transformation mutant. The phenotype of comekk1 disruptant was similar to that of cmk1, a Saccharomyces cerevisiae Fus3/Kss1 MAPK homolog mutant. Moreover, comekk1 and cmk1 mutants were sensitive to high osmotic and salinity stresses, indicating that Comekk1p/Cmk1p signal transduction is involved in stress tolerance. The transformants of the wild type and the comekk1 mutant expressing a constitutively active form of the CoMEKK1 showed slower hyphal growth and abnormal appressorium formation, whereas those of the cmk1 disruptant did not. A Cmk1p-green fluorescent protein (GFP) intracellular localization experiment indicated that nuclear localization of the Cmk1p-GFP fusion protein induced by salt stress was diminished in comekk1 mutants. These results indicate that Comekk1p functions upstream of Cmk1p.

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