scholarly journals Posttranslational Regulation of Ty1 Retrotransposition by Mitogen-Activated Protein Kinase Fus3

1998 ◽  
Vol 18 (5) ◽  
pp. 2502-2513 ◽  
Author(s):  
Darryl Conte ◽  
Ellen Barber ◽  
Mukti Banerjee ◽  
David J. Garfinkel ◽  
M. Joan Curcio
Keyword(s):  
Protein Kinase ◽  
Proteolytic Processing ◽  
Mitogen Activated Protein Kinase ◽  
Pheromone Response ◽  
Environmental Signals ◽  
Pheromone Response Pathway ◽  
Mitogen Activated Protein ◽  
Associated Proteins ◽  
Steady State Levels ◽  
Ty1 Retrotransposition

ABSTRACT Ty1 retrotransposons in Saccharomyces cerevisiae are maintained in a state of transpositional dormancy. We isolated a mutation, rtt100-1, that increases the transposition of genomic Ty1 elements 18- to 56-fold but has little effect on the transposition of related Ty2 elements. rtt100-1 was shown to be a null allele of the FUS3 gene, which encodes a haploid-specific mitogen-activated protein kinase. In fus3mutants, the levels of Ty1 RNA, protein synthesis, and proteolytic processing were not altered relative to those in FUS3strains but steady-state levels of TyA, integrase, and reverse transcriptase proteins and Ty1 cDNA were all increased. These findings suggest that Fus3 suppresses Ty1 transposition by destabilizing viruslike particle-associated proteins. The Fus3 kinase is activated through the mating-pheromone response pathway by phosphorylation at basal levels in naive cells and at enhanced levels in pheromone-treated cells. We demonstrate that suppression of Ty1 transposition in naive cells requires basal levels of Fus3 activation. Substitution of conserved amino acids required for activation of Fus3 derepressed Ty1 transposition. Moreover, epistasis analyses revealed that components of the pheromone response pathway that act upstream of Fus3, including Ste4, Ste5, Ste7, and Ste11, are required for the posttranslational suppression of Ty1 transposition by Fus3. The regulation of Ty1 transposition by Fus3 provides a haploid-specific mechanism through which environmental signals can modulate the levels of retrotransposition.

A yeast mitogen-activated protein kinase homolog (Mpk1p) mediates signalling by protein kinase C

1993 ◽  
Vol 13 (5) ◽  
pp. 3067-3075 ◽  
Author(s):  
K S Lee ◽  
K Irie ◽  
Y Gotoh ◽  
Y Watanabe ◽  
H Araki ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Map Kinase ◽  
Protein Kinases ◽  
Map Kinases ◽  
Pheromone Response ◽  
Pheromone Response Pathway ◽  
Kinase C ◽  
Mitogen Activated Protein ◽  
Kinase Cascade ◽  
Protein Kinase Cascade

Mitogen-activated protein (MAP) kinases are activated in response to a variety of stimuli through a protein kinase cascade that results in their phosphorylation on tyrosine and threonine residues. The molecular nature of this cascade is just beginning to emerge. Here we report the isolation of a Saccharomyces cerevisiae gene encoding a functional analog of mammalian MAP kinases, designated MPK1 (for MAP kinase). The MPK1 gene was isolated as a dosage-dependent suppressor of the cell lysis defect associated with deletion of the BCK1 gene. The BCK1 gene is also predicted to encode a protein kinase which has been proposed to function downstream of the protein kinase C isozyme encoded by PKC1. The MPK1 gene possesses a 1.5-kb uninterrupted open reading frame predicted to encode a 53-kDa protein. The predicted Mpk1 protein (Mpk1p) shares 48 to 50% sequence identity with Xenopus MAP kinase and with the yeast mating pheromone response pathway components, Fus3p and Kss1p. Deletion of MPK1 resulted in a temperature-dependent cell lysis defect that was virtually indistinguishable from that resulting from deletion of BCK1, suggesting that the protein kinases encoded by these genes function in a common pathway. Expression of Xenopus MAP kinase suppressed the defect associated with loss of MPK1 but not the mating-related defects associated with loss of FUS3 or KSS1, indicating functional conservation between the former two protein kinases. Mutation of the presumptive phosphorylated tyrosine and threonine residues of Mpk1p individually to phenylalanine and alanine, respectively, severely impaired Mpk1p function. Additional epistasis experiments, and the overall architectural similarity between the PKC1-mediated pathway and the pheromone response pathway, suggest that Pkc1p regulates a protein kinase cascade in which Bck1p activates a pair of protein kinases, designated Mkk1p and Mkk2p (for MAP kinase-kinase), which in turn activate Mpk1p.

Isoflurane Preconditions Hippocampal Neurons against Oxygen–Glucose Deprivation

2005 ◽  
Vol 103 (3) ◽  
pp. 532-539 ◽  
Author(s):  
Philip E. Bickler ◽  
Xinhua Zhan ◽  
Christian S. Fahlman
Keyword(s):  
Endoplasmic Reticulum ◽  
Protein Kinase ◽  
Hippocampal Slice ◽  
Binding Protein ◽  
Glucose Deprivation ◽  
Mitogen Activated Protein Kinase ◽  
Oxygen Glucose Deprivation ◽  
Hippocampal Slice Cultures ◽  
Mitogen Activated Protein ◽  
Associated Proteins

Background Isoflurane preconditions neurons to improve tolerance of subsequent ischemia in both intact animal models and in in vitro preparations. The mechanisms for this protection remain largely undefined. Because isoflurane increases intracellular Ca2+ concentrations and Ca2+ is involved in many processes related to preconditioning, the authors hypothesized that isoflurane preconditions neurons via Ca2+-dependent processes involving the Ca2+- binding protein calmodulin and the mitogen-activated protein kinase-ERK pathway. Methods The authors used a preconditioning model in which organotypic cultures of rat hippocampus were exposed to 0.5-1.5% isoflurane for a 2-h period 24 h before an ischemia-like injury of oxygen-glucose deprivation. Survival of CA1, CA3, and dentate neurons was assessed 48 later, along with interval measurements of intracellular Ca2+ concentration (fura-2 fluorescence microscopy in CA1 neurons), mitogen-activated protein kinase p42/44, and the survival associated proteins Akt and GSK-3beta (in situ immunostaining and Western blots). Results Preconditioning with 0.5-1.5% isoflurane decreased neuron death in CA1 and CA3 regions of hippocampal slice cultures after oxygen-glucose deprivation. The preconditioning period was associated with an increase in basal intracellular Ca2+ concentration of 7-15%, which involved Ca2+ release from inositol triphosphate-sensitive stores in the endoplasmic reticulum, and transient phosphorylation of mitogen-activated protein kinase p42/44 and the survival-associated proteins Akt and GSK-3beta. Preconditioning protection was eliminated by the mitogen-activated extracellular kinase inhibitor U0126, which prevented phosphorylation of p44 during preconditioning, and by calmidazolium, which antagonizes the effects of Ca2+-bound calmodulin. Conclusions Isoflurane, at clinical concentrations, preconditions neurons in hippocampal slice cultures by mechanisms that apparently involve release of Ca2+ from the endoplasmic reticulum, transient increases in intracellular Ca2+ concentration, the Ca2+ binding protein calmodulin, and phosphorylation of the mitogen-activated protein kinase p42/44.

scholarly journals Posttranslational Regulation of Ty1 Retrotransposition by Mitogen-Activated Protein Kinase Fus3

1998 ◽  
Vol 18 (9) ◽  
pp. 5620-5620
Author(s):  
Darryl Conte ◽  
Ellen Barber ◽  
Mukti Banerjee ◽  
David J. Garfinkel ◽  
M. Joan Curcio
Keyword(s):  
Protein Kinase ◽  
Mitogen Activated Protein Kinase ◽  
Posttranslational Regulation ◽  
Mitogen Activated Protein ◽  
Ty1 Retrotransposition

scholarly journals Role of the Unfolded Protein Response in Regulating the Mucin-Dependent Filamentous-Growth Mitogen-Activated Protein Kinase Pathway

2015 ◽  
Vol 35 (8) ◽  
pp. 1414-1432 ◽  
Author(s):  
Hema Adhikari ◽  
Nadia Vadaie ◽  
Jacky Chow ◽  
Lauren M. Caccamise ◽  
Colin A. Chavel ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Unfolded Protein Response ◽  
Mapk Pathway ◽  
Filamentous Growth ◽  
Proteolytic Processing ◽  
Mitogen Activated Protein Kinase ◽  
Unfolded Protein ◽  
Mitogen Activated Protein ◽  
The Unfolded Protein Response ◽  
Protein Response

Signaling mucins are evolutionarily conserved regulators of signal transduction pathways. The signaling mucin Msb2p regulates the Cdc42p-dependent mitogen-activated protein kinase (MAPK) pathway that controls filamentous growth in yeast. The cleavage and release of the glycosylated inhibitory domain of Msb2p is required for MAPK activation. We show here that proteolytic processing of Msb2p was induced by underglycosylation of its extracellular domain. Cleavage of underglycosylated Msb2p required the unfolded protein response (UPR), a quality control (QC) pathway that operates in the endoplasmic reticulum (ER). The UPR regulator Ire1p, which detects misfolded/underglycosylated proteins in the ER, controlled Msb2p cleavage by regulating transcriptional induction of Yps1p, the major protease that processes Msb2p. Accordingly, the UPR was required for differentiation to the filamentous cell type. Cleavage of Msb2p occurred in conditional trafficking mutants that trap secretory cargo in the endomembrane system. Processed Msb2p was delivered to the plasma membrane, and its turnover by the ubiquitin ligase Rsp5p and ESCRT attenuated the filamentous-growth pathway. We speculate that the QC pathways broadly regulate signaling glycoproteins and their cognate pathways by recognizing altered glycosylation patterns that can occur in response to extrinsic cues.

scholarly journals Analysis of Mitogen-Activated Protein Kinase Signaling Specificity in Response to Hyperosmotic Stress: Use of an Analog-Sensitive HOG1 Allele

2006 ◽  
Vol 5 (8) ◽  
pp. 1215-1228 ◽  
Author(s):  
Patrick J. Westfall ◽  
Jeremy Thorner
Keyword(s):  
Protein Kinase ◽  
Cross Talk ◽  
Kinase Activity ◽  
Hyperosmotic Stress ◽  
Mitogen Activated Protein Kinase ◽  
Hog Pathway ◽  
Pheromone Response ◽  
Mapk Kinase ◽  
Signaling Specificity ◽  
Mitogen Activated Protein

ABSTRACT When confronted with a marked increase in external osmolarity, budding yeast (Saccharomyces cerevisiae) cells utilize a conserved mitogen-activated protein kinase (MAPK) signaling cascade (the high-osmolarity glycerol or HOG pathway) to elicit cellular responses necessary to permit continued growth. One input that stimulates the HOG pathway requires the integral membrane protein and putative osmosensor Sho1, which recruits and enables activation of the MAPK kinase kinase Ste11. In mutants that lack the downstream MAPK kinase (pbs2Δ) or the MAPK (hog1Δ) of the HOG pathway, Ste11 activated by hyperosmotic stress is able to inappropriately stimulate the pheromone response pathway. This loss of signaling specificity is known as cross talk. To determine whether it is the Hog1 polypeptide per se or its kinase activity that is necessary to prevent cross talk, we constructed a fully functional analog-sensitive allele of HOG1 to permit acute inhibition of this enzyme without other detectable perturbations of the cell. We found that the catalytic activity of Hog1 is required continuously to prevent cross talk between the HOG pathway and both the pheromone response and invasive growth pathways. Moreover, contrary to previous reports, we found that the kinase activity of Hog1 is necessary for its stress-induced nuclear import. Finally, our results demonstrate a role for active Hog1 in maintaining signaling specificity under conditions of persistently high external osmolarity.

scholarly journals Activation of the Kss1 Invasive-Filamentous Growth Pathway Induces Ty1 Transcription and Retrotransposition inSaccharomyces cerevisiae

2000 ◽  
Vol 20 (15) ◽  
pp. 5766-5776 ◽  
Author(s):  
Antonin Morillon ◽  
Mathias Springer ◽  
Pascale Lesage
Keyword(s):  
Mapk Cascade ◽  
Mitogen Activated Protein Kinase ◽  
Cell Type ◽  
Environmental Signals ◽  
Mitogen Activated Protein ◽  
Response To Stress ◽  
Ty1 Retrotransposition ◽  
Diploid Cells ◽  
Low Nitrogen ◽  
Growth Pathway

ABSTRACT Using a set of genomic TY1A-lacZ fusions, we show that Ste12 and Tec1, two transcription factors of the Kss1 mitogen-activated protein kinase (MAPK) cascade activate Ty1 transcription inSaccharomyces cerevisiae. This result strongly suggests that the invasive-filamentous pathway regulates Ty1 transcription. Since this pathway is active in diploid cells, we suspected that Ty1 transposition might occur in this cell type, despite the fact that this event has been never reported before (unless activated by heterologous promoters such as that of GAL1). We demonstrate here that constitutive activation of the invasive-filamentous pathway by theSTE11-4 allele or by growth in low-nitrogen medium induces Ty1 transcription and retrotransposition in diploid cells. We show that Ty1 retrotransposition can be activated by STE11-4 in haploid cells as well. Our findings provide the first evidence that Ty1 retrotransposition can be activated by environmental signals that affect differentiation. Activation of the Kss1 MAPK cascade by stress is known to cause filament formation that permits the search for nutrients away from the colonization site. We propose that activation of Ty1 retrotransposition by this cascade could play a role in adaptive mutagenesis in response to stress.

scholarly journals The vtc4 Gene Influences Polyphosphate Storage, Morphogenesis, and Virulence in the Maize Pathogen Ustilago maydis

2006 ◽  
Vol 5 (8) ◽  
pp. 1399-1409 ◽  
Author(s):  
Kylie J. Boyce ◽  
Matthias Kretschmer ◽  
James W. Kronstad
Keyword(s):  
Protein Kinase ◽  
Nutrient Status ◽  
Ustilago Maydis ◽  
Mitogen Activated Protein Kinase ◽  
Yeast Cells ◽  
In Planta ◽  
Environmental Signals ◽  
Mitogen Activated Protein ◽  
Kinase Cascade ◽  
Pka Pathway

ABSTRACT The maize pathogen Ustilago maydis switches from budding to filamentous, dikaryotic growth in response to environmental signals including nutrient status, growth in the host, and the presence of mating pheromones. The filamentous dikaryon is capable of proliferating within host tissue to cause disease symptoms including tumors. The transition from yeast cells to hyphal filaments is regulated by a mitogen-activated protein kinase cascade and a cyclic-AMP-protein kinase A (PKA) pathway. Serial analysis of gene expression with PKA mutants identified orthologs of components of the PHO phosphate acquisition pathway as transcriptional targets of the PKA pathway, and these included genes for Pho84, an acid phosphatase, and the vacuolar transport chaperones Vtc1 and Vtc4. In Saccharomyces cerevisiae, Vtc4p is required during the fusion of inorganic-phosphate-containing vesicles to the vacuolar membrane and the consequent accumulation of phosphate stored as polyphosphate (polyP) in the vacuole. We found that deletion of vtc4 in U. maydis also reduced polyP stored in vacuoles. Intriguingly, Δvtc4 mutants possessed a filamentous cellular morphology, in contrast to the budding, yeast-like growth of the wild-type parent. The Δvtc4 mutants also displayed decreased symptom development and reduced proliferation in planta. The interaction with PKA signaling was further investigated by the generation of Δvtc4 ubc1 double mutants. Deletion of vtc4 completely suppressed the multiple-budded phenotype of a Δubc1 mutant, indicating that polyP stores are essential for this PKA-induced trait. Overall, this study reveals a novel role for PKA-regulated polyP accumulation in the control of fungal morphogenesis and virulence.

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