scholarly journals NHP6A and NHP6B, which encode HMG1-like proteins, are candidates for downstream components of the yeast SLT2 mitogen-activated protein kinase pathway.

1994 ◽  
Vol 14 (4) ◽  
pp. 2391-2403 ◽  
Author(s):  
C Costigan ◽  
D Kolodrubetz ◽  
M Snyder
Keyword(s):  
Protein Kinase ◽  
Synthetic Lethality ◽  
Mapk Pathway ◽  
Mitogen Activated Protein Kinase ◽  
Growth Defect ◽  
Temperature Sensitive ◽  
Restrictive Temperature ◽  
Mitogen Activated Protein ◽  
Multiple Copies ◽  
Delta Cells

The yeast SLK1 (BCK1) gene encodes a mitogen-activated protein kinase (MAPK) activator protein which functions upstream in a protein kinase cascade that converges on the MAPK Slt2p (Mpk1p). Dominant alleles of SLK1 have been shown to bypass the conditional lethality of a protein kinase C mutation, pkc1-delta, suggesting that Pkc1p may regulate Slk1p function. Slk1p has an important role in morphogenesis and growth control, and deletions of the SLK1 gene are lethal in a spa2-delta mutant background. To search for genes that interact with the SLK1-SLT2 pathway, a synthetic lethal suppression screen was carried out. Genes which in multiple copies suppress the synthetic lethality of slk1-1 spa2-delta were identified, and one, the NHP6A gene, has been extensively characterized. The NHP6A gene and the closely related NHP6B gene were shown previously to encode HMG1-like chromatin-associated proteins. We demonstrate here that these genes are functionally redundant and that multiple copies of either NHP6A or NHP6B suppress slk1-delta and slt2-delta. Strains from which both NHP6 genes were deleted (nhp6-delta mutants) share many phenotypes with pkc1-delta, slk1-delta, and slt2-delta mutants. nhp6-delta cells display a temperature-sensitive growth defect that is rescued by the addition of 1 M sorbitol to the medium, and they are sensitive to starvation. nhp6-delta strains also exhibit a variety of morphological and cytoskeletal defects. At the restrictive temperature for growth, nhp6-delta mutant cells contain elongated buds and enlarged necks. Many cells have patches of chitin staining on their cell surfaces, and chitin deposition is enhanced at the necks of budded cells. nhp6-delta cells display a defect in actin polarity and often accumulate large actin chunks. Genetic and phenotypic analysis indicates that NHP6A and NHP6B function downstream of SLT2. Our results indicate that the Slt2p MAPK pathway in Saccharomyces cerevisiae may mediate its function in cell growth and morphogenesis, at least in part, through high-mobility group proteins.

NHP6A and NHP6B, which encode HMG1-like proteins, are candidates for downstream components of the yeast SLT2 mitogen-activated protein kinase pathway

1994 ◽  
Vol 14 (4) ◽  
pp. 2391-2403
Author(s):  
C Costigan ◽  
D Kolodrubetz ◽  
M Snyder
Keyword(s):  
Protein Kinase ◽  
Synthetic Lethality ◽  
Mapk Pathway ◽  
Mitogen Activated Protein Kinase ◽  
Growth Defect ◽  
Temperature Sensitive ◽  
Restrictive Temperature ◽  
Mitogen Activated Protein ◽  
Multiple Copies ◽  
Delta Cells

The yeast SLK1 (BCK1) gene encodes a mitogen-activated protein kinase (MAPK) activator protein which functions upstream in a protein kinase cascade that converges on the MAPK Slt2p (Mpk1p). Dominant alleles of SLK1 have been shown to bypass the conditional lethality of a protein kinase C mutation, pkc1-delta, suggesting that Pkc1p may regulate Slk1p function. Slk1p has an important role in morphogenesis and growth control, and deletions of the SLK1 gene are lethal in a spa2-delta mutant background. To search for genes that interact with the SLK1-SLT2 pathway, a synthetic lethal suppression screen was carried out. Genes which in multiple copies suppress the synthetic lethality of slk1-1 spa2-delta were identified, and one, the NHP6A gene, has been extensively characterized. The NHP6A gene and the closely related NHP6B gene were shown previously to encode HMG1-like chromatin-associated proteins. We demonstrate here that these genes are functionally redundant and that multiple copies of either NHP6A or NHP6B suppress slk1-delta and slt2-delta. Strains from which both NHP6 genes were deleted (nhp6-delta mutants) share many phenotypes with pkc1-delta, slk1-delta, and slt2-delta mutants. nhp6-delta cells display a temperature-sensitive growth defect that is rescued by the addition of 1 M sorbitol to the medium, and they are sensitive to starvation. nhp6-delta strains also exhibit a variety of morphological and cytoskeletal defects. At the restrictive temperature for growth, nhp6-delta mutant cells contain elongated buds and enlarged necks. Many cells have patches of chitin staining on their cell surfaces, and chitin deposition is enhanced at the necks of budded cells. nhp6-delta cells display a defect in actin polarity and often accumulate large actin chunks. Genetic and phenotypic analysis indicates that NHP6A and NHP6B function downstream of SLT2. Our results indicate that the Slt2p MAPK pathway in Saccharomyces cerevisiae may mediate its function in cell growth and morphogenesis, at least in part, through high-mobility group proteins.

scholarly journals Suppressors of a Saccharomyces cerevisiae pkc1 mutation identify alleles of the phosphatase gene PTC1 and of a novel gene encoding a putative basic leucine zipper protein.

Genetics ◽  
1995 ◽  
Vol 141 (4) ◽  
pp. 1275-1285 ◽  
Author(s):  
K N Huang ◽  
L S Symington
Keyword(s):  
Protein Kinase ◽  
Leucine Zipper ◽  
Mapk Pathway ◽  
Mitogen Activated Protein Kinase ◽  
Growth Defect ◽  
Temperature Sensitive ◽  
Gene Encoding ◽  
Basic Leucine Zipper ◽  
Mapk Cascades ◽  
Synthetically Lethal

Abstract The PKC1 gene product, protein kinase C, regulates a mitogen-activated protein kinase (MAPK) cascade, which is implicated in cell wall metabolism. Previously, we identified the pkc1-4 allele in a screen for mutants with increased rates of recombination, indicating that PKC1 may also regulate DNA metabolism. The pkc1-4 allele also conferred a temperature-sensitive (ts) growth defect. Extragenic suppressors were isolated that suppress both the ts and hyperrecombination phenotypes conferred by the pkc1-4 mutation. Eight of these suppressors for into two complementation groups, designated KCS1 and KCS2. KCS1 was cloned and found to encode a novel protein with homology to the basic leucine zipper family of transcription factors. KCS2 is allelic with PTC1, a previously identified type 2C serine/threonine protein phosphatase. Although mutation of either KCS1 or PTC1 causes little apparent phenotype, the kcs1 delta ptc1 delta double mutant fails to grow at 30 degrees. Furthermore, the ptc1 deletion mutation is synthetically lethal in combination with a mutation in MPK1, which encodes a MAPK homologue proposed to act in the PKC1 pathway. Because PTC1 was initially isolated as a component of the Hog1p MAPK pathway, it appears that these two MAPK cascades share a common regulatory feature.

scholarly journals PDK1 Homologs Activate the Pkc1–Mitogen-Activated Protein Kinase Pathway in Yeast

1999 ◽  
Vol 19 (12) ◽  
pp. 8344-8352 ◽  
Author(s):  
Maiko Inagaki ◽  
Tobias Schmelzle ◽  
Kyoko Yamaguchi ◽  
Kenji Irie ◽  
Michael N. Hall ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Mapk Pathway ◽  
Phosphorylation Site ◽  
Genetic Selection ◽  
Mitogen Activated Protein Kinase ◽  
Yeast Cells ◽  
Temperature Sensitive ◽  
Mutant Form ◽  
Mitogen Activated Protein

ABSTRACT PDK1 (phosphoinositide-dependent kinase 1) is a mammalian growth factor-regulated serine/threonine kinase. Using a genetic selection based on a mutant form of the yeast MAP kinase kinase Ste7, we isolated a gene, PKH2, encoding a structurally and functionally conserved yeast homolog of PDK1. Yeast cells lacking bothPKH2 and PKH1, encoding another PDK1 homolog, were nonviable, indicating that Pkh1 and Pkh2 share an essential function. A temperature-sensitive mutant, pkh1D398Gpkh2, was phenotypically similar to mutants defective in the Pkc1–mitogen-activated protein kinase (MAPK) pathway. Genetic epistasis analyses, the phosphorylation of Pkc1 by Pkh2 in vitro, and reduced Pkc1 activity in the pkh1D398G pkh2mutant indicate that Pkh functions upstream of Pkc1. The Pkh2 phosphorylation site in Pkc1 (Thr-983) is part of a conserved PDK1 target motif and essential for Pkc1 function. Thus, the yeast PDK1 homologs activate Pkc1 and the Pkc1-effector MAPK pathway.

scholarly journals BRO1, a novel gene that interacts with components of the Pkc1p-mitogen-activated protein kinase pathway in Saccharomyces cerevisiae.

1996 ◽  
Vol 16 (6) ◽  
pp. 2585-2593 ◽  
Author(s):  
M E Nickas ◽  
M P Yaffe
Keyword(s):  
Protein Kinase ◽  
Mitogen Activated Protein Kinase ◽  
Yeast Cells ◽  
Growth Defect ◽  
Binding Motif ◽  
Temperature Sensitive ◽  
Cell Integrity ◽  
Gene Encoding ◽  
Mitogen Activated Protein ◽  
Kinase Pathway

Yeast cells with mutations in BRO1 display phenotypes similar to those caused by deletion of BCK1, a gene encoding a MEK kinase that functions in a mitogen-activated protein kinase pathway mediating maintenance of cell integrity. bro1 cells exhibit a temperature-sensitive growth defect that is suppressed by the addition of osmotic stabilizers or Ca2+ to the growth medium or by additional copies of the BCK1 gene. At permissive temperatures, bro1 mutants are sensitive to caffeine and respond abnormally to nutrient limitation. A null mutation in BRO1 is synthetically lethal with null mutations in BCK1, MPK1, which encodes a mitogen-activated protein kinase that functions downstream of Bck1p, or PKC1, a gene encoding a protein kinase C homolog that activates Bck1p. Analysis of the isolated BRO1 gene revealed that it encodes a novel, 97-kDa polypeptide which contains a putative SH3 domain-binding motif and is homologous to a protein of unknown function in Caenorhabditis elegans.

scholarly journals Expression of transgenes enriched in rare codons is enhanced by the MAPK pathway

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Jackson Peterson ◽  
Siqi Li ◽  
Erin Kaltenbrun ◽  
Ozgun Erdogan ◽  
Christopher M. Counter
Keyword(s):  
Amino Acids ◽  
Protein Kinase ◽  
Mapk Pathway ◽  
Mitogen Activated Protein Kinase ◽  
Rare Codons ◽  
Synonymous Codons ◽  
Multiple Components ◽  
Human Genes ◽  
Regulatory Module ◽  
Mitogen Activated Protein

AbstractThe ability to translate three nucleotide sequences, or codons, into amino acids to form proteins is conserved across all organisms. All but two amino acids have multiple codons, and the frequency that such synonymous codons occur in genomes ranges from rare to common. Transcripts enriched in rare codons are typically associated with poor translation, but in certain settings can be robustly expressed, suggestive of codon-dependent regulation. Given this, we screened a gain-of-function library for human genes that increase the expression of a GFPrare reporter encoded by rare codons. This screen identified multiple components of the mitogen activated protein kinase (MAPK) pathway enhancing GFPrare expression. This effect was reversed with inhibitors of this pathway and confirmed to be both codon-dependent and occur with ectopic transcripts naturally coded with rare codons. Finally, this effect was associated, at least in part, with enhanced translation. We thus identify a potential regulatory module that takes advantage of the redundancy in the genetic code to modulate protein expression.

scholarly journals Ghrelin exerts a proliferative effect on a rat pituitary somatotroph cell line via the mitogen-activated protein kinase pathway

2004 ◽  
pp. 233-240 ◽  
Author(s):  
AM Nanzer ◽  
S Khalaf ◽  
AM Mozid ◽  
RC Fowkes ◽  
MV Patel ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Protein Kinase ◽  
Cell Line ◽  
Kinase Inhibitor ◽  
Thymidine Incorporation ◽  
Mapk Pathway ◽  
Mitogen Activated Protein Kinase ◽  
Gh3 Cells ◽  
Rat Pituitary ◽  
Mitogen Activated Protein

OBJECTIVES: Ghrelin is a brain-gut peptide with GH-releasing and appetite-inducing activities and a widespread tissue distribution. Ghrelin is the endogenous ligand of the GH secretagogue receptor type 1a (GHS-R1a), and both ghrelin and the GHS-R1a are expressed in the pituitary. There are conflicting data regarding the effects of ghrelin on cell proliferation. A positive effect on proliferation and activation of the mitogen-activated protein kinase (MAPK) pathway has been found in hepatoma, adipose, cardiomyocyte and prostate cell lines. However, ghrelin has also been shown to have anti-proliferative effects on breast, lung and thyroid cell lines. We therefore examined the effect of ghrelin on the rat pituitary cell line GH3. METHODS: RT-PCR was used for the detection of GHS-R1a and pre-proghrelin mRNA expression in GH3 cells. The effect of ghrelin on cell proliferation was studied using [(3)H]thymidine incorporation; cell counting and the activation of the MAPK pathway were studied using immunoblotting and inhibitors of the extracellular signal-regulated kinase 1 and 2 (ERK 1/2), protein kinase C (PKC) and tyrosine phosphatase pathways. RESULTS: GHS-R1a and ghrelin mRNA expression were detected in GH3 cells. Ghrelin, at 10(-10) to 10(-6) M concentrations, significantly increased [(3)H]thymidine incorporation (at 10(-9) M, 183+/-13% (means+/-s.e.m.) compared with untreated controls), while 12-phorbol 13-myristate acetate (PMA) at 10(-7) M (used as a positive control) caused a 212+/-14% increase. A reproducible stimulatory effect of desoctanoyl ghrelin was also observed on [(3)H]thymidine incorporation (135+/-5%; P<0.01 at 10(-9) M compared with control), as well as on the cell count (control 6.8 x 10(4)+/-8.7 x 10(3) cells/ml vs desoctanoyl ghrelin (10(-9) M) 1.04 x 10(5)+/-7.5 x 10(3) cells/ml; P<0.01). Ghrelin caused a significant increase in phosphorylated ERK 1/2 in immunoblotting, while desoctanoyl ghrelin showed a smaller but also significant stimulatory effect. The positive effect of ghrelin and desoctanoyl ghrelin on [(3)H]thymidine incorporation was abolished by the MAPK kinase inhibitor U0126, the PKC inhibitor GF109203X and the tyrosine kinase inhibitor tyrphostin 23, suggesting that the ghrelin-induced cell proliferation of GH3 cells is mediated both via a PKC-MAPK-dependent pathway and via a tyrosine kinase-dependent pathway. This could also be clearly demonstrated by Western blot analysis, where a transient increase in ERK 1/2 phosphorylation by ghrelin was attenuated by all three inhibitors. CONCLUSION: We have shown a novel role for ghrelin in stimulating the proliferation of a somatotroph pituitary tumour cell line, suggesting that ERK activation is involved in mediating the effects of ghrelin on cell proliferation. Desoctanoyl ghrelin showed a similar effect. As ghrelin has been shown to be expressed in both normal and adenomatous pituitary tissue, locally produced ghrelin may play a role in pituitary tumorigenesis via an autocrine/paracrine pathway.

scholarly journals The vaccinia virus-stimulated mitogen-activated protein kinase (MAPK) pathway is required for virus multiplication

2004 ◽  
Vol 381 (2) ◽  
pp. 437-446 ◽  
Author(s):  
Anderson A. ANDRADE ◽  
Patrícia N. G. SILVA ◽  
Anna C. T. C. PEREIRA ◽  
Lirlândia P. de SOUSA ◽  
Paulo C. P. FERREIRA ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Tyrosine Kinase ◽  
Vaccinia Virus ◽  
Mapk Pathway ◽  
Decisive Role ◽  
Virus Multiplication ◽  
Mitogen Activated Protein Kinase ◽  
Actin Dynamics ◽  
Kinase Activation ◽  
Mitogen Activated Protein

Early events play a decisive role in virus multiplication. We have shown previously that activation of MAPK/ERK1/2 (mitogen-activated protein kinase/extracellular-signal-regulated kinase 1/2) and protein kinase A are pivotal for vaccinia virus (VV) multiplication [de Magalhães, Andrade, Silva, Sousa, Ropert, Ferreira, Kroon, Gazzinelli and Bonjardim (2001) J. Biol. Chem. 276, 38353–38360]. In the present study, we show that VV infection provoked a sustained activation of both ERK1/2 and RSK2 (ribosomal S6 kinase 2). Our results also provide evidence that this pattern of kinase activation depends on virus multiplication and ongoing protein synthesis and is maintained independently of virus DNA synthesis. It is noteworthy that the VGF (VV growth factor), although involved, is not essential for prolonged ERK1/2 activation. Furthermore, our findings suggest that the VV-stimulated ERK1/2 activation also seems to require actin dynamics, microtubule polymerization and tyrosine kinase phosphorylation. The VV-stimulated pathway MEK/ERK1/2/RSK2 (where MEK stands for MAPK/ERK kinase) leads to phosphorylation of the ternary complex factor Elk-1 and expression of the early growth response (egr-1) gene, which kinetically paralleled the kinase activation. The recruitment of this pathway is biologically relevant, since its disruption caused a profound effect on viral thymidine kinase gene expression, viral DNA replication and VV multiplication. This pattern of sustained kinase activation after VV infection is unique. In addition, by connecting upstream signals generated at the cytoskeleton and by tyrosine kinase, the MEK/ERK1/2/RSK2 cascade seems to play a decisive role not only at early stages of the infection, i.e. post-penetration, but is also crucial to define the fate of virus progeny.

scholarly journals APPL1 mediates adiponectin-stimulated p38 MAPK activation by scaffolding the TAK1-MKK3-p38 MAPK pathway

2011 ◽  
Vol 300 (1) ◽  
pp. E103-E110 ◽  
Author(s):  
Xiaoban Xin ◽  
Lijun Zhou ◽  
Caleb M. Reyes ◽  
Feng Liu ◽  
Lily Q. Dong
Keyword(s):  
Protein Kinase ◽  
P38 Mapk ◽  
Mapk Pathway ◽  
Adaptor Protein ◽  
Mapk Signaling ◽  
Mitogen Activated Protein Kinase ◽  
Scaffolding Protein ◽  
Mapk Activation ◽  
P38 Mapk Pathway ◽  
Mitogen Activated Protein

The adaptor protein APPL1 mediates the stimulatory effect of adiponectin on p38 mitogen-activated protein kinase (MAPK) signaling, yet the underlying mechanism remains unclear. Here we show that, in C2C12 cells, overexpression or suppression of APPL1 enhanced or suppressed, respectively, adiponectin-stimulated p38 MAPK upstream kinase cascade, consisting of transforming growth factor-β-activated kinase 1 (TAK1) and mitogen-activated protein kinase kinase 3 (MKK3). In vitro affinity binding and coimmunoprecipitation experiments revealed that TAK1 and MKK3 bind to different regions of APPL1, suggesting that APPL1 functions as a scaffolding protein to facilitate adiponectin-stimulated p38 MAPK activation. Interestingly, suppressing APPL1 had no effect on TNFα-stimulated p38 MAPK phosphorylation in C2C12 myotubes, indicating that the stimulatory effect of APPL1 on p38 MAPK activation is selective. Taken together, our study demonstrated that the TAK1-MKK3 cascade mediates adiponectin signaling and uncovers a scaffolding role of APPL1 in regulating the TAK1-MKK3-p38 MAPK pathway, specifically in response to adiponectin stimulation.

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.

Sign in / Sign up

Export Citation Format

Share Document