scholarly journals Perturbation of the Nucleus: A Novel Hog1p-independent, Pkc1p-dependent Consequence of Hypertonic Shock in Yeast

2001 ◽  
Vol 12 (6) ◽  
pp. 1835-1841 ◽  
Author(s):  
Jayasri Nanduri ◽  
Alan M. Tartakoff
Keyword(s):  
Map Kinase ◽  
Rna Synthesis ◽  
Kinase Activity ◽  
Nuclear Proteins ◽  
Cell Integrity ◽  
Kinase C ◽  
Nucleolar Proteins ◽  
Map Kinase Cascade ◽  
Kinase Cascade ◽  
Hypertonic Shock

Hypertonic shock of Saccharomyces cerevisiaeactivates the Hog1p MAP kinase cascade. In contrast, protein kinase C (Pkc1p) and the “cell integrity” MAP kinase cascade are critical for the response to hypotonic shock. We observed that hypertonic shock transiently relocated many, but not all, nuclear and nucleolar proteins to the cytoplasm. We hypothesized that the relocation of nuclear proteins was due to activation of the Hog1p kinase cascade, yet, surprisingly, Hog1p was not required for these effects. In contrast, Pkc1p kinase activity was required, although the Pkc1p MAP kinase cascade and several factors known to lie upstream and downstream of Pkc1p were not. Moreover, sudden induction of a hyperactive form of Pkc1p was sufficient to relocate nuclear proteins. Taken together, these observations show that the scope of involvement of Pkc1p in the organization of the nucleus considerably exceeds what has been characterized previously. The relocation of nuclear proteins is likely to account for the profound inhibition of RNA synthesis that was observed during hypertonic shock.

Rho5p downregulates the yeast cell integrity pathway

2002 ◽  
Vol 115 (15) ◽  
pp. 3139-3148 ◽  
Author(s):  
Hans-Peter Schmitz ◽  
Stefanie Huppert ◽  
Anja Lorberg ◽  
Jürgen J. Heinisch
Keyword(s):  
Map Kinase ◽  
Signal Transduction Pathway ◽  
Eukaryotic Cell ◽  
Cell Integrity ◽  
Calcofluor White ◽  
Cell Functions ◽  
Map Kinase Cascade ◽  
Independent Functions ◽  
Dependent Signal ◽  
Kinase Cascade

The Rho family of proteins and their effectors are key regulators involved in many eukaryotic cell functions. In Saccharomyces cerevisiae the family consists of six members, Rho1p to Rho5p and Cdc42p. With the exception of Rho5p, these enzymes have been assigned different biological functions,including the regulation of polar growth, morphogenesis, actin cytoskeleton,budding and secretion. Here we show that a rho5 deletion results in an increased activity of the protein kinase C (Pkc1p)-dependent signal transduction pathway. Accordingly, the deletion shows an increased resistance to drugs such as caffeine, Calcofluor white and Congo red, which indicates activation of the pathway. In contrast, overexpression of an activated RHO5Q91H mutant renders cells more sensitive to these drugs. We conclude that Rho5p acts as an off-switch for the MAP-kinase cascade, which differentiates between MAP-kinase-dependent and -independent functions of Pkc1p. Kinetics of actin depolarisation and repolarisation after heat treatment of rho5 deletions as well as strains overexpressing the activated RHO5Q91H allele provide further evidence for such a function.

scholarly journals Loss of sustained Fus3p kinase activity and the G1 arrest response in cells expressing an inappropriate pheromone receptor.

1996 ◽  
Vol 16 (8) ◽  
pp. 4478-4485 ◽  
Author(s):  
A Couve ◽  
J P Hirsch
Keyword(s):  
Map Kinase ◽  
G Protein ◽  
Kinase Activity ◽  
G1 Arrest ◽  
Wild Type ◽  
Pheromone Response Pathway ◽  
Cycle Arrest ◽  
Map Kinase Cascade ◽  
Receptor Inhibition ◽  
Kinase Cascade

The yeast pheromone response pathway is mediated by two G protein-linked receptors, each of which is expressed only in its specific cell type. The STE3DAF mutation results in inappropriate expression of the a-factor receptor in MATa cells. Expression of this receptor in the inappropriate cell type confers resistance to pheromone-induced G1 arrest, a phenomenon that we have termed receptor inhibition. The ability of STE3DAF cells to cycle in the presence of pheromone was found to correlate with reduced phosphorylation of the cyclin-dependent kinase inhibitor Far1p. Measurement of Fus3p mitogen-activated protein (MAP) kinase activity in wild-type and STE3DAF cells showed that induction of Fus3p activity was the same in both strains at times of up to 1 h after pheromone treatment. However, after 2 or more hours, Fus3p activity declined in STE3DAF cells but remained high in wild-type cells. The level of inducible FUS1 RNA paralleled the changes seen in Fus3p activity. Short-term activation of the Fus3p MAP kinase is therefore sufficient for the early transcriptional induction response to pheromone, but sustained activation is required for cell cycle arrest. Escape from the cell cycle arrest response was not seen in wild-type cells treated with low doses of pheromone, indicating that receptor inhibition is not simply a result of weak signaling but rather acts selectively at late times during the response. STE3DAF was found to inhibit the pheromone response pathway at a step between the G beta subunit and Ste5p, the scaffolding protein that binds the components of the MAP kinase phosphorylation cascade. Overexpression of Ste20p, a kinase thought to act between the G protein and the MAP kinase cascade, suppressed the STE3DAF phenotype. These findings are consistent with a model in which receptor inhibition acts by blocking the signaling pathway downstream of G protein dissociation and upstream of MAP kinase cascade activation, at a step that could directly involve Ste20p.

Abnormalities in protein kinase C and MAP kinase cascade in mesangial cells cultured under high glucose conditions

1995 ◽  
Vol 9 (4) ◽  
pp. 246-248 ◽  
Author(s):  
Masakazu Haneda ◽  
Ryuichi Kikkawa ◽  
Toshiro Sugimoto ◽  
Daisuke Koya ◽  
Shin-ichi Araki ◽  
...  
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Map Kinase ◽  
High Glucose ◽  
Mesangial Cells ◽  
Kinase C ◽  
Map Kinase Cascade ◽  
Kinase Cascade ◽  
Cells Cultured

scholarly journals Transforming growth factor β 1 inhibits mitogen-activated protein kinase induced by basic fibroblast growth factor in smooth muscle cells

1996 ◽  
Vol 316 (1) ◽  
pp. 167-173 ◽  
Author(s):  
Eliane BERROU ◽  
Michaëla FONTENAY-ROUPIE ◽  
Rozenn QUARCK ◽  
Fergus R. McKENZIE ◽  
Sylviane LÉVY-TOLEDANO ◽  
...  
Keyword(s):  
Growth Factor ◽  
Map Kinase ◽  
Kinase Activity ◽  
Transforming Growth Factor ◽  
Mitogen Activated Protein Kinase ◽  
Map Kinase Cascade ◽  
Mitogen Activated Protein ◽  
Kinase Cascade ◽  
Tgf Β1

Stimulation of smooth muscle cells with basic fibroblast growth factor (bFGF) results in the activation of the mitogen-activated protein kinase (MAP kinase) cascade and leads to cell proliferation. We show that transforming growth factor β1 (TGF-β1), at concentrations that completely inhibited bFGF-induced mitogenic activity, decreased bFGF-induced MAP kinase activity. Under these conditions, tyrosine and threonine phosphorylations of MAP kinase were differentially affected depending on the time period of TGF-β1 pretreatment. After a short (30 min) TGF-β1 pretreatment, the bFGF-mediated increase in phosphorylation of p42mapk on threonine was inhibited, with no effect on the level of phosphotyrosine or decrease in the electrophoretic mobility of p42mapk. This suggests that TGF-β1 inhibited MAP kinase activity through the action of a serine/threonine phosphatase. In contrast, a longer TGF-β1 pretreatment (4 h) partly inhibited the bFGF-induced MAP kinase mobility shift and correlated with the inhibition of phosphorylation on both threonine and tyrosine, suggesting that long-term TGF-β1 treatment prevented activation of the MAP kinase cascade or directly blocked MAP kinase. The ability of long-term (4 h) but not short-term (30 min) TGF-β1 pretreatment to inhibit MAP kinase activity was completely dependent on protein synthesis and suggests that TGF-β1 inhibits MAP kinase activity by two distinct mechanisms. These findings provide a molecular basis for the growth-inhibitory action of TGF-β1 on bFGF-induced mitogenic activity.

Role for lipid signaling and the cell integrity MAP kinase cascade in yeast septum biogenesis

2003 ◽  
Vol 43 (2) ◽  
pp. 71-78 ◽  
Author(s):  
Sabina Tahirovic ◽  
Markus Schorr ◽  
Angela Then ◽  
Jürgen Berger ◽  
Heinz Schwarz ◽  
...  
Keyword(s):  
Map Kinase ◽  
Lipid Signaling ◽  
Cell Integrity ◽  
Map Kinase Cascade ◽  
Kinase Cascade
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