scholarly journals Melanin Biosynthesis in the Maize Pathogen Cochliobolus heterostrophus Depends on Two Mitogen-Activated Protein Kinases, Chk1 and Mps1, and the Transcription Factor Cmr1

2007 ◽  
Vol 6 (3) ◽  
pp. 421-429 ◽  
Author(s):  
Noa Eliahu ◽  
Aeid Igbaria ◽  
Mark S. Rose ◽  
Benjamin A. Horwitz ◽  
Sophie Lev
Keyword(s):  
Transcription Factor ◽  
Protein Kinases ◽  
Noncoding Rna ◽  
Magnaporthe Grisea ◽  
Cochliobolus Heterostrophus ◽  
Transcriptional Level ◽  
Melanin Biosynthesis ◽  
Mitogen Activated Protein Kinases ◽  
Mitogen Activated Protein ◽  
Hyperosmotic Environment

ABSTRACT The maize pathogen Cochliobolus heterostrophus requires two mitogen-activated protein kinases (MAPKs), Chk1 and Mps1, to produce normal pigmentation. Young colonies of mps1 and chk1 deletion mutants have a white and autolytic appearance, which was partially rescued by a hyperosmotic environment. We isolated the transcription factor Cmr1, an ortholog of Colletotrichum lagenarium Cmr1 and Magnaporthe grisea Pig1, which regulates melanin biosynthesis in C. heterostrophus. Deletion of CMR1 in C. heterostrophus resulted in mutants that lacked dark pigmentation and acquired an orange-pink color. In cmr1 deletion strains the expression of putative scytalone dehydratase (SCD1) and hydroxynaphthalene reductase (BRN1 and BRN2) genes involved in melanin biosynthesis was undetectable, whereas expression of PKS18, encoding a polyketide synthase, was only moderately reduced. In chk1 and mps1 mutants expression of PKS18, SCD1, BRN1, BRN2, and the transcription factor CMR1 itself was very low in young colonies, slightly up-regulated in aging colonies, and significantly induced in hyperosmotic conditions, compared to invariably high expression in the wild type. These findings indicate that two MAPKs, Chk1 and Mps1, affect Cmr1 at the transcriptional level and this influence is partially overridden in stress conditions including aging culture and hyperosmotic environment. Surprisingly, we found that the CMR1 gene was transcribed in both sense and antisense directions, apparently producing mRNA as well as a long noncoding RNA transcript. Expression of the antisense CMR1 was also Chk1 and Mps1 dependent. Analysis of chromosomal location of the melanin biosynthesis genes in C. heterostrophus resulted in identification of a small gene cluster comprising BRN1, CMR1, and PKS18. Since expression of all three genes depends on Chk1 and Mps1 MAPKs, we suggest their possible epigenetic regulation.

The Induction of Megakaryocyte Differentiation Is Accompanied by Selective Ser133 Phosphorylation of the Transcription Factor CREB in Both HEL Cell Line and Primary CD34+Cells

Blood ◽  
1998 ◽  
Vol 92 (2) ◽  
pp. 472-480 ◽  
Author(s):  
Giorgio Zauli ◽  
Davide Gibellini ◽  
Marco Vitale ◽  
Paola Secchiero ◽  
Claudio Celeghini ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Protein Kinase ◽  
Protein Kinases ◽  
Specific Inhibitor ◽  
Surface Expression ◽  
Mitogen Activated Protein Kinases ◽  
Creb Phosphorylation ◽  
Mitogen Activated Protein ◽  
Hel Cells ◽  
Megakaryocyte Differentiation

The addition of thrombopoietin (TPO) to HEL cells, cultured in a chemically defined serum-free medium, induced a rapid and dose-dependent phosphorylation of the transcription factor CREB on serine133 (PSer133), as detected by Western blot analysis. TPO also significantly increased the transactivation of CRE-dependent promoter, as determined in transient transfection experiments. On the other hand, neither erythropoietin (Epo; 1 to 10 U) nor hemin (10−7 mol/L) were able to significantly stimulate CREB-PSer133 or to activate CRE-promoter in HEL cells. Although pharmacological inhibitors of protein kinase C (chelerytrine and BIM) and protein kinase A (H-89) failed to block the TPO-mediated CREB phosphorylation, a specific inhibitor of the mitogen-activated protein kinases (PD98059) completely blocked the ability of TPO to stimulate CREB-PSer133. Moreover, PD98059 significantly decreased the ability of TPO to upregulate the surface expression of the αIIbβ3 megakaryocytic marker in HEL cells. In parallel, primary CD34+ hematopoietic cells were seeded in liquid cultures supplemented with 100 ng/mL of TPO and examined by immunofluorescence for the coexpression of αIIbβ3 and CREB-PSer133 at various time points. High levels of nuclear CREB-PSer133 were unequivocally demonstrated in αIIbβ3+cells, including morphologically recognizable megakaryocytes. Taken together, these data suggest that CREB plays a role in modulating the expression of genes critical for megakaryocyte differentiation and that the TPO-mediated CREB phosphorylation seems to be regulated via mitogen-activated protein kinases.

The Induction of Megakaryocyte Differentiation Is Accompanied by Selective Ser133 Phosphorylation of the Transcription Factor CREB in Both HEL Cell Line and Primary CD34+Cells

Blood ◽  
1998 ◽  
Vol 92 (2) ◽  
pp. 472-480 ◽  
Author(s):  
Giorgio Zauli ◽  
Davide Gibellini ◽  
Marco Vitale ◽  
Paola Secchiero ◽  
Claudio Celeghini ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Protein Kinase ◽  
Protein Kinases ◽  
Specific Inhibitor ◽  
Surface Expression ◽  
Mitogen Activated Protein Kinases ◽  
Creb Phosphorylation ◽  
Mitogen Activated Protein ◽  
Hel Cells ◽  
Megakaryocyte Differentiation

Abstract The addition of thrombopoietin (TPO) to HEL cells, cultured in a chemically defined serum-free medium, induced a rapid and dose-dependent phosphorylation of the transcription factor CREB on serine133 (PSer133), as detected by Western blot analysis. TPO also significantly increased the transactivation of CRE-dependent promoter, as determined in transient transfection experiments. On the other hand, neither erythropoietin (Epo; 1 to 10 U) nor hemin (10−7 mol/L) were able to significantly stimulate CREB-PSer133 or to activate CRE-promoter in HEL cells. Although pharmacological inhibitors of protein kinase C (chelerytrine and BIM) and protein kinase A (H-89) failed to block the TPO-mediated CREB phosphorylation, a specific inhibitor of the mitogen-activated protein kinases (PD98059) completely blocked the ability of TPO to stimulate CREB-PSer133. Moreover, PD98059 significantly decreased the ability of TPO to upregulate the surface expression of the αIIbβ3 megakaryocytic marker in HEL cells. In parallel, primary CD34+ hematopoietic cells were seeded in liquid cultures supplemented with 100 ng/mL of TPO and examined by immunofluorescence for the coexpression of αIIbβ3 and CREB-PSer133 at various time points. High levels of nuclear CREB-PSer133 were unequivocally demonstrated in αIIbβ3+cells, including morphologically recognizable megakaryocytes. Taken together, these data suggest that CREB plays a role in modulating the expression of genes critical for megakaryocyte differentiation and that the TPO-mediated CREB phosphorylation seems to be regulated via mitogen-activated protein kinases.

scholarly journals Role of MPK4 in pathogen-associated molecular pattern-triggered alternative splicing in Arabidopsis

2019 ◽  
Author(s):  
Jeremie Bazin ◽  
Kiruthiga Mariappan ◽  
Thomas Blein ◽  
Ronny Voelz ◽  
Martin Crespi ◽  
...  
Keyword(s):  
Alternative Splicing ◽  
Protein Kinases ◽  
Transcriptome Analysis ◽  
Splicing Factors ◽  
Transcriptional Level ◽  
Mitogen Activated Protein Kinases ◽  
Molecular Pattern ◽  
Mitogen Activated Protein ◽  
Alternatively Spliced ◽  
Pathogen Associated Molecular Pattern

AbstractAlternative splicing (AS) of pre-mRNAs in plants is an important mechanism of gene regulation in environmental stress tolerance but plant signals involved are essentially unknown. Pathogen-associated molecular pattern (PAMP)-triggered immunity (PTI) is mediated by mitogen-activated protein kinases and the majority of PTI defense genes are regulated by MPK3, MPK4 and MPK6. These responses have been mainly analyzed at the transcriptional level, however many splicing factors are direct targets of MAPKs. Here, we studied alternative splicing induced by the PAMP flagellin in Arabidopsis. We identified 506 PAMP-induced differentially alternatively spliced (DAS) genes. Although many DAS genes are targets of nonsense-mediated degradation (NMD), only 19% are potential NMD targets. Importantly, of the 506 PAMP-induced DAS genes, only 89 overlap with the set of 1849 PAMP-induced differentially expressed genes (DEG), indicating that transcriptome analysis does not identify most DASevents. Global DAS analysis of mpk3, mpk4, and mpk6 mutants revealed that MPK4 is a key regulator of PAMP-induced differential splicing, regulating AS of a number of splicing factors and immunity-related protein kinases, such as the calcium-dependent protein kinase CPK28, the cysteine-rich receptor like kinases CRK13 and CRK29 or the FLS2 co-receptor SERK4/BKK1. These data suggest that MAP kinase regulation of splicing factors is a key mechanism in PAMP-induced AS regulation of PTI.Significance statementAlternative pre-mRNA splicing (AS) affects plant responses to environmental stresses. So far, however, the regulation of AS is little understood. Here, we studied AS induced by the pathogen-associated molecular pattern (PAMP) flagellin in Arabidopsis. We identified 506 differentially alternatively spliced (DAS) genes, 89 of which overlap with the 1849 DEG, indicating that the majority of DAS events go undetected by common transcriptome analysis. PAMP-triggered immunity is mediated by mitogen-activated protein kinases. Global DAS analysis of MAPK mutants revealed that MPK4 is a key regulator of AS by affecting splicing factors and a number of important protein kinases involved in immunity. Since PAMP-triggered phosphorylation of several splicing factors is directly mediated by MAPKs, we discovered a key mechanism of AS regulation.

Sevoflurane Inhibits Phorbol-Myristate-Acetate-induced Activator Protein-1 Activation in Human T Lymphocytes in Vitro : Potential Role of the p38-Stress Kinase Pathway

2004 ◽  
Vol 101 (3) ◽  
pp. 710-721 ◽  
Author(s):  
Torsten Loop ◽  
Patrick Scheiermann ◽  
David Doviakue ◽  
Frank Musshoff ◽  
Matjaz Humar ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Protein Kinases ◽  
Phorbol Myristate Acetate ◽  
Volatile Anesthetics ◽  
Nuclear Factor ◽  
Activator Protein 1 ◽  
Myristate Acetate ◽  
Mitogen Activated Protein Kinases ◽  
Mitogen Activated Protein

Background Modulation of immune defense mechanisms by volatile anesthetics during general anesthesia may compromise postoperative immune competence and healing reactions and affect the infection rate and the rate of tumor metastases disseminated during surgery. Several mechanisms have been suggested to account for these effects. The current study was undertaken to examine the molecular mechanisms underlying these observations. Methods Effects of sevoflurane, isoflurane, and desflurane were studied in vitro in primary human CD3 T-lymphocytes. DNA-binding activity of the transcription factor activator protein-1 (AP-1) was assessed using an electrophoretic mobility shift assay. Phorbol-myristate-acetate-dependent effects of sevoflurane on the phosphorylation of the mitogen-activated protein kinases were studied using Western blots, the trans-activating potency of AP-1 was determined using reporter gene assays, and the cytokine release was measured using enzyme-linked immunosorbent assays. Results Sevoflurane inhibited activation of the transcription factor AP-1. This effect was specific, as the activity of nuclear factor kappabeta, nuclear factor of activated T cells, and specific protein-1 was not altered and several other volatile anesthetics studied did not affect AP-1 activation. Sevoflurane-mediated suppression of AP-1 could be observed in primary CD3 lymphocytes from healthy volunteers, was time-dependent and concentration-dependent, and occurred at concentrations that are clinically achieved. It resulted in an inhibition of AP-1-driven reporter gene activity and of the expression of the AP-1 target gene interleukin-3. Suppression of AP-1 was associated with altered phosphorylation of p38 mitogen-activated protein kinases. Conclusion The data demonstrate that sevoflurane is a specific inhibitor of AP-1 and may thus provide a molecular mechanism for the antiinflammatory effects associated with sevoflurane administration.

scholarly journals SUMO enables substrate selectivity by mitogen-activated protein kinases to regulate immunity in plants

2021 ◽  
Vol 118 (10) ◽  
pp. e2021351118
Author(s):  
Vivek Verma ◽  
Anjil K. Srivastava ◽  
Catherine Gough ◽  
Alberto Campanaro ◽  
Moumita Srivastava ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Protein Kinases ◽  
Defense Responses ◽  
Substrate Selectivity ◽  
Modification System ◽  
Mitogen Activated Protein Kinases ◽  
Cellular Events ◽  
Sumo Proteases ◽  
Mitogen Activated Protein ◽  
Elicitor Treatment

The versatility of mitogen-activated protein kinases (MAPKs) in translating exogenous and endogenous stimuli into appropriate cellular responses depends on its substrate specificity. In animals, several mechanisms have been proposed about how MAPKs maintain specificity to regulate distinct functional pathways. However, little is known of mechanisms that enable substrate selectivity in plant MAPKs. Small ubiquitin-like modifier (SUMO), a posttranslational modification system, plays an important role in plant development and defense by rapid reprogramming of cellular events. In this study we identified a functional SUMO interaction motif (SIM) in Arabidopsis MPK3 and MPK6 that reveals a mechanism for selective interaction of MPK3/6 with SUMO-conjugated WRKY33, during defense. We show that WRKY33 is rapidly SUMOylated in response to Botrytis cinerea infection and flg22 elicitor treatment. SUMOylation mediates WRKY33 phosphorylation by MPKs and consequent transcription factor activity. Disruption of either WRKY33 SUMO or MPK3/6 SIM sites attenuates their interaction and inactivates WRKY33-mediated defense. However, MPK3/6 SIM mutants show normal interaction with a non-SUMOylated form of another transcription factor, SPEECHLESS, unraveling a role for SUMOylation in differential substrate selectivity by MPKs. We reveal that the SUMO proteases, SUMO PROTEASE RELATED TO FERTILITY1 (SPF1) and SPF2 control WRKY33 SUMOylation and demonstrate a role for these SUMO proteases in defense. Our data reveal a mechanism by which MPK3/6 prioritize molecular pathways by differentially selecting substrates using the SUMO–SIM module during defense responses.

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