scholarly journals The AngFus3 Mitogen-Activated Protein Kinase Controls Hyphal Differentiation and Secondary Metabolism in Aspergillus niger

2015 ◽  
Vol 14 (6) ◽  
pp. 602-615 ◽  
Author(s):  
Bert-Ewald Priegnitz ◽  
Ulrike Brandt ◽  
Khomaizon A. K. Pahirulzaman ◽  
Jeroen S. Dickschat ◽  
André Fleißner
Keyword(s):  
Aspergillus Niger ◽  
Map Kinase ◽  
Secondary Metabolism ◽  
Filamentous Fungi ◽  
Cell Types ◽  
Growth Conditions ◽  
Mitogen Activated Protein Kinase ◽  
Content Type ◽  
Mitogen Activated Protein ◽  
Upstream Kinase

ABSTRACTAdaptation to a changing environment is essential for the survival and propagation of sessile organisms, such as plants or fungi. Filamentous fungi commonly respond to a worsening of their growth conditions by differentiation of asexually or sexually produced spores. The formation of these specialized cell types is, however, also triggered as part of the general life cycle by hyphal age or density. Spores typically serve for dispersal and, therefore, translocation but can also act as resting states to endure times of scarcity. Eukaryotic differentiation in response to environmental and self-derived signals is commonly mediated by three-tiered mitogen-activated protein (MAP) kinase signaling cascades. Here, we report that the MAP kinase Fus3 of the black moldAspergillus niger(AngFus3) and its upstream kinase AngSte7 control vegetative spore formation and secondary metabolism. Mutants lacking these kinases are defective in conidium induction in response to hyphal density but are fully competent in starvation-induced sporulation, indicating that conidiation inA. nigeris triggered by various independent signals. In addition, the mutants exhibit an altered profile of volatile metabolites and secrete dark pigments into the growth medium, suggesting a dysregulation of the secondary metabolism. By assigning the AngFus3 MAP kinase pathway to the transduction of a potentially self-derived trigger, this work contributes to the unraveling of the intricate signaling networks controlling fungal differentiation. Moreover, our data further support earlier observations that differentiation and secondary metabolism are tightly linked in filamentous fungi.

scholarly journals p38α Mitogen-activated Protein Kinase Sensitizes Cells to Apoptosis Induced by Different Stimuli

2004 ◽  
Vol 15 (2) ◽  
pp. 922-933 ◽  
Author(s):  
Almudena Porras ◽  
Susana Zuluaga ◽  
Emma Black ◽  
Amparo Valladares ◽  
Alberto M. Alvarez ◽  
...  
Keyword(s):  
Map Kinase ◽  
Cell Types ◽  
Mitogen Activated Protein Kinase ◽  
Extracellular Signal Regulated Kinase ◽  
Survival Pathways ◽  
Proapoptotic Protein ◽  
Extracellular Signal ◽  
Survival Pathway ◽  
Mitogen Activated Protein

p38α mitogen-activated protein (MAP) kinase is a broadly expressed signaling molecule that participates in the regulation of cellular responses to stress as well as in the control of proliferation and survival of many cell types. We have used cell lines derived from p38α knockout mice to study the role of this signaling pathway in the regulation of apoptosis. Here, we show that cardiomyocytes and fibroblasts lacking p38α are more resistant to apoptosis induced by different stimuli. The reduced apoptosis of p38α-deficient cells correlates with decreased expression of the mitochondrial proapoptotic protein Bax and the apoptosis-inducing receptor Fas/CD-95. Cells lacking p38α also have increased extracellular signal-regulated kinase (ERKs) MAP kinase activity, and the up-regulation of this survival pathway seems to be at least partially responsible for the reduced levels of apoptosis in the absence of p38α. Phosphorylation of the transcription factor STAT3 on Ser-727, mediated by the extracellular signal-regulated kinase MAP kinase pathway, may contribute to the decrease in both Bax and Fas expression in p38α-/- cells. Thus, p38α seems to sensitize cells to apoptosis via both up-regulation of proapoptotic proteins and down-regulation of survival pathways.

scholarly journals Mitogen-Activated Protein Kinase-Dependent Interleukin-1α Intracrine Signaling Is Modulated by YopP during Yersinia enterocolitica Infection

2011 ◽  
Vol 80 (1) ◽  
pp. 289-297 ◽  
Author(s):  
Rumu Bose ◽  
Josephine Thinwa ◽  
Paola Chaparro ◽  
Youmin Zhong ◽  
Santanu Bose ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Map Kinase ◽  
Yersinia Enterocolitica ◽  
Nuclear Translocation ◽  
P38 Map Kinase ◽  
Mitogen Activated Protein Kinase ◽  
Virulence Plasmid ◽  
Content Type ◽  
Mitogen Activated Protein ◽  
Interleukin 1Α

ABSTRACTYersinia enterocoliticais a food-borne pathogen that preferentially infects the Peyer's patches and mesenteric lymph nodes, causing an acute inflammatory reaction. Even thoughY. enterocoliticainduces a robust inflammatory response during infection, the bacterium has evolved a number of virulence factors to limit the extent of this response. We previously demonstrated that interleukin-1α (IL-1α) was critical for the induction of gut inflammation characteristic ofY. enterocoliticainfection. More recently, the known actions of IL-1α are becoming more complex because IL-1α can function both as a proinflammatory cytokine and as a nuclear factor. In this study, we tested the ability ofY. enterocoliticato modulate intracellular IL-1α-dependent IL-8 production in epithelial cells. Nuclear translocation of pre-IL-1α protein and IL-1α-dependent secretion of IL-8 into the culture supernatant were increased during infection with a strain lacking the 70-kDa virulence plasmid compared to the case during infection with the wild type, suggesting thatYersiniaouter proteins (Yops) might be involved in modulating intracellular IL-1α signaling. Infection of HeLa cells with a strain lacking theyopPgene resulted in increased nuclear translocation of pre-IL-1α and IL-1α-dependent secretion of IL-8 similar to what is observed with bacteria lacking the virulence plasmid. YopP is a protein acetylase that inhibits mitogen-activated protein kinase (MAP kinase)- and NF-κB-dependent signal transduction pathways. Nuclear translocation of pre-IL-1α and IL-1α-dependent secretion of IL-8 in response toYersinia enterocoliticainfection were dependent on extracellular signal-regulated kinase (ERK) and p38 MAP kinase signaling but independent of NF-κB. These data suggest thatY. enterocoliticainhibits intracellular pre-IL-1α signaling and subsequent proinflammatory responses through inhibition of MAP kinase pathways.

scholarly journals Light Signaling Regulates Aspergillus niger Biofilm Formation by Affecting Melanin and Extracellular Polysaccharide Biosynthesis

mBio ◽  
2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Wenjun Sun ◽  
Ying Yu ◽  
Jiao Chen ◽  
Bin Yu ◽  
Tianpeng Chen ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Aspergillus Niger ◽  
Signaling Pathway ◽  
Theoretical Basis ◽  
Mapk Signaling ◽  
Mapk Signaling Pathway ◽  
Mitogen Activated Protein Kinase ◽  
Light Signaling ◽  
Content Type ◽  
Mitogen Activated Protein

ABSTRACT Light is an important signal source in nature, which regulates the physiological cycle, morphogenetic pathways, and secondary metabolites of fungi. As an external pressure on Aspergillus niger, light signaling transmits stress signals into the cell via the mitogen-activated protein kinase (MAPK) signaling pathway. Studying the effect of light on the biofilm of A. niger will provide a theoretical basis for light in the cultivation of filamentous fungi and industrial applications. Here, the characterization of A. niger biofilm under different light intensities confirmed the effects of light signaling. Our results indicated that A. niger intensely accumulated protective mycelial melanin under light illumination. We also discovered that the RlmA transcription factor in the MAPK signaling pathway is activated by light signaling to promote the synthesis of melanin, chitin, and other exopolysaccharides. However, the importance of melanin to A. niger biofilm is rarely reported; therefore, we knocked out key genes of the melanin biosynthetic pathway—Abr1 and Ayg1. Changes in hydrophobicity and electrostatic forces resulted in the decrease of biofilm caused by the decrease of melanin in mutants. IMPORTANCE As an important industrial filamentous fungus, Aspergillus niger can perceive light. The link between light signaling and A. niger biofilm is worthy of further study since reports are lacking in this area. This study found that light signaling promotes biofilm production in A. niger, wherein melanin plays an important role. It was further discovered that the RlmA transcription factor in the mitogen-activated protein kinase (MAPK) signaling pathway was mediated by light signaling to promote the synthesis of melanin and extracellular polysaccharides. These findings set the stage for light signal regulation of biofilm in filamentous fungi and provide a theoretical basis for the development of a new light-controlled biofilm method to improve biofilm-based industrial fermentation.

scholarly journals Mitogen-activated protein kinase translocates to the nucleus during ischaemia and is activated during reperfusion

1997 ◽  
Vol 323 (3) ◽  
pp. 785-790 ◽  
Author(s):  
Yoichi MIZUKAMI ◽  
Ken-ichi YOSHIDA
Keyword(s):  
Map Kinase ◽  
Tyrosine Phosphorylation ◽  
Mitogen Activated Protein Kinase ◽  
Nuclear Fraction ◽  
Cytosol Fraction ◽  
Extracellular Signal ◽  
Ischaemia And Reperfusion ◽  
Mitogen Activated Protein ◽  
Upstream Kinase ◽  
Cellular Stresses

Growth factors and various cellular stresses are known to activate mitogen-activated protein (MAP) kinase, which plays a role in conveying signals from the cytosol to the nucleus. The phosphorylation of MAP kinase is thought to be a prerequisite for translocation. Here, we investigate the translocation and activation of MAP kinase during ischaemia and reperfusion in perfused rat heart. Ischaemia (0–40 min) induces the translocation of MAP kinase from the cytosol fraction to the nuclear fraction. Immunohistochemical observation shows that MAP kinase staining in the nucleus is enhanced after ischaemia for 40 min. Unexpectedly, tyrosine phosphorylation of MAP kinase is unchanged in the nuclear fraction during ischaemia, indicating that unphosphorylated MAP kinase translocates from the cytosol to the nucleus. During reperfusion (0–30 min), after ischaemia for 20 min, tyrosine phosphorylation of MAP kinase in the nuclear fraction is increased with a peak at 10 min of reperfusion. The activation is confirmed by MAP kinase activity with similar kinetics to the tyrosine phosphorylation. However, the amount of MAP kinase in the fraction is almost constant during reperfusion for 10 min. Although an upstream kinase for MAP kinase, MAP kinase/extracellular signal-regulated kinase kinase (MEK)-1, remains in the cytosol throughout ischaemia and reperfusion, MEK-2, another upstream kinase for MAP kinase, is constantly present in the nucleus as well as in the cytoplasm, based on analyses by fractionation and immunohistochemistry. Furthermore, MEK-2 activity in the nuclear fraction is rapidly increased during post-ischaemic reperfusion. These findings demonstrate that nuclear MAP kinase is activated by tyrosine phosphorylation during reperfusion, probably by MEK-2.

scholarly journals Differential induction of the mitogen-activated protein kinase pathway by bacterial lipopolysaccharide in cultured monocytes and astrocytes

1996 ◽  
Vol 313 (2) ◽  
pp. 519-524 ◽  
Author(s):  
Susan A. WILLIS ◽  
Perry D. NISEN
Keyword(s):  
Map Kinase ◽  
Cell Line ◽  
Transcription Initiation ◽  
Cell Types ◽  
Mitogen Activated Protein Kinase ◽  
Intracellular Camp ◽  
Monocytic Cells ◽  
Essential Components ◽  
Mitogen Activated Protein ◽  
Camp Levels

We recently reported that cyclic AMP (cAMP) specifically inhibits lipopolysaccharide (LPS)-induced interleukin 1β (IL-1β) transcription initiation in astrocytic cells but enhances the LPS induction of IL-1β in monocytic cells. The purpose of this study was to determine how cAMP differentially regulates LPS-induced IL-1β transcription in these two cell types. Two essential components of the mitogen-activated protein (MAP) kinase signal-transduction pathway, extracellular-signal-regulated kinase (ERK2; p41mapk) and Raf-1, have been shown to be targets of LPS stimulation in other cell types, and therefore may be linked to the regulation of IL-1β transcription. In the human astrocytic cell line, U-373MG, LPS was found to strongly activate (and cAMP to inhibit) both ERK2 and Raf-1. In the human monocytic cell line, THP-1, LPS minimally activated ERK2 and did not activate Raf-1. These findings suggest that, in astrocytic cells, elevated intracellular cAMP levels may negatively regulate LPS activation of IL-1β via the MAP kinase signalling pathway. In contrast, this pathway is not significantly activated by LPS in monocytic cells, thus inhibition by elevated intracellular cAMP levels would not affect IL-1β transcription.

scholarly journals Distinct Roles of a Mitogen-Activated Protein Kinase in Cytokinesis between Different Life Cycle Forms of Trypanosoma brucei

2013 ◽  
Vol 13 (1) ◽  
pp. 110-118 ◽  
Author(s):  
Ying Wei ◽  
Ziyin Li
Keyword(s):  
Life Cycle ◽  
Protein Kinase ◽  
Map Kinase ◽  
Trypanosoma Brucei ◽  
Bloodstream Form ◽  
Mitogen Activated Protein Kinase ◽  
Content Type ◽  
Procyclic Form ◽  
Moderate Growth ◽  
Mitogen Activated Protein

ABSTRACT Mitogen-activated protein kinase (MAPK) modules are evolutionarily conserved signaling cascades that function in response to the environment and play crucial roles in intracellular signal transduction in eukaryotes. The involvement of a MAP kinase in regulating cytokinesis in yeast, animals, and plants has been reported, but the requirement for a MAP kinase for cytokinesis in the early-branching protozoa is not documented. Here, we show that a MAP kinase homolog (TbMAPK6) from Trypanosoma brucei plays distinct roles in cytokinesis in two life cycle forms of T. brucei . TbMAPK6 is distributed throughout the cytosol in the procyclic form but is localized in both the cytosol and the nucleus in the bloodstream form. RNA interference (RNAi) of TbMAPK6 results in moderate growth inhibition in the procyclic form but severe growth defects and rapid cell death in the bloodstream form. Moreover, TbMAPK6 appears to be implicated in furrow ingression and cytokinesis completion in the procyclic form but is essential for cytokinesis initiation in the bloodstream form. Despite the distinct defects in cytokinesis in the two forms, RNAi of TbMAPK6 also caused defective basal body duplication/segregation in a small cell population in both life cycle forms. Altogether, our results demonstrate the involvement of the TbMAPK6-mediated pathway in regulating cytokinesis in trypanosomes and suggest distinct roles of TbMAPK6 in cytokinesis between different life cycle stages of T. brucei .

scholarly journals Novel Antifungal Compound Z-705 Specifically Inhibits Protein Kinase C of Filamentous Fungi

2019 ◽  
Vol 85 (10) ◽  
Author(s):  
Asumi Sugahara ◽  
Akira Yoshimi ◽  
Fumio Shoji ◽  
Tomonori Fujioka ◽  
Kiyoshi Kawai ◽  
...  
Keyword(s):  
Cell Wall ◽  
Protein Kinase C ◽  
Protein Kinase ◽  
Filamentous Fungi ◽  
Magnaporthe Grisea ◽  
Rice Blast Fungus ◽  
Mitogen Activated Protein Kinase ◽  
Content Type ◽  
Kinase C ◽  
Mitogen Activated Protein

ABSTRACTThe cell wall integrity signaling (CWIS) pathway is involved in fungal cell wall biogenesis. This pathway is composed of sensor proteins, protein kinase C (PKC), and the mitogen-activated protein kinase (MAPK) pathway, and it controls the transcription of many cell wall-related genes. PKC plays a pivotal role in this pathway; deficiencies in PkcA in the model filamentous fungusAspergillus nidulansand in MgPkc1p in the rice blast fungusMagnaporthe griseaare lethal. This suggests that PKC in filamentous fungi is a potential target for antifungal agents. In the present study, to search for MgPkc1p inhibitors, we carried outin silicoscreening by three-dimensional (3D) structural modeling and performed growth inhibition tests forM. griseaon agar plates. From approximately 800,000 candidate compounds, we selected Z-705 and evaluated its inhibitory activity against chimeric PKC expressed inSaccharomyces cerevisiaecells in which the kinase domain of nativeS. cerevisiaePKC was replaced with those of PKCs of filamentous fungi. Transcriptional analysis ofMLP1, which encodes a downstream factor of PKC inS. cerevisiae, and phosphorylation analysis of the mitogen-activated protein kinase (MAPK) Mpk1p, which is activated downstream of PKC, revealed that Z-705 specifically inhibited PKCs of filamentous fungi. Moreover, the inhibitory activity of Z-705 was similar to that of a well-known PKC inhibitor, staurosporine. Interestingly, Z-705 inhibited melanization induced by cell wall stress inM. grisea. We discuss the relationships between PKC and melanin biosynthesis.IMPORTANCEA candidate inhibitor of filamentous fungal protein kinase C (PKC), Z-705, was identified byin silicoscreening. A screening system to evaluate the effects of fungal PKC inhibitors was constructed inSaccharomyces cerevisiae. Using this system, we found that Z-705 is highly selective for filamentous fungal PKC in comparison withS. cerevisiaePKC. Analysis of theAGS1mRNA level, which is regulated by Mps1p mitogen-activated protein kinase (MAPK) via PKC, in the rice blast fungusMagnaporthe grisearevealed that Z-705 had a PKC inhibitory effect comparable to that of staurosporine. Micafungin induced hyphal melanization inM. grisea, and this melanization, which is required for pathogenicity ofM. grisea, was inhibited by PKC inhibition by both Z-705 and staurosporine. The mRNA levels of4HNR,3HNR, andSCD1, which are essential for melanization inM. grisea, were suppressed by both PKC inhibitors.

scholarly journals Signaling through mitogen-activated protein kinase and Rac/Rho does not duplicate the effects of activated Ras on skeletal myogenesis.

1997 ◽  
Vol 17 (7) ◽  
pp. 3547-3555 ◽  
Author(s):  
M B Ramocki ◽  
S E Johnson ◽  
M A White ◽  
C L Ashendel ◽  
S F Konieczny ◽  
...  
Keyword(s):  
Map Kinase ◽  
Signaling Pathways ◽  
Transcriptional Activation ◽  
Intracellular Signaling ◽  
Mitogen Activated Protein Kinase ◽  
Ras Signaling ◽  
Negative Effects ◽  
Intracellular Signaling Pathway ◽  
Helix Loop Helix ◽  
Mitogen Activated Protein

The ability of basic helix-loop-helix muscle regulatory factors (MRFs), such as MyoD, to convert nonmuscle cells to a myogenic lineage is regulated by numerous growth factor and oncoprotein signaling pathways. Previous studies have shown that H-Ras 12V inhibits differentiation to a skeletal muscle lineage by disrupting MRF function via a mechanism that is independent of the dimerization, DNA binding, and inherent transcriptional activation properties of the proteins. To investigate the intracellular signaling pathway(s) that mediates the inhibition of MRF-induced myogenesis by oncogenic Ras, we tested two transformation-defective H-Ras 12V effector domain variants for their ability to alter terminal differentiation. H-Ras 12V,35S retains the ability to activate the Raf/MEK/mitogen-activated protein (MAP) kinase cascade, whereas H-Ras 12V,40C is unable to interact directly with Raf-1 yet still influences other signaling intermediates, including Rac and Rho. Expression of each H-Ras 12V variant in C3H10T1/2 cells abrogates MyoD-induced activation of the complete myogenic program, suggesting that MAP kinase-dependent and -independent Ras signaling pathways individually block myogenesis in this model system. However, additional studies with constitutively activated Rac1 and RhoA proteins revealed no negative effects on MyoD-induced myogenesis. Similarly, treatment of Ras-inhibited myoblasts with the MEK1 inhibitor PD98059 revealed that elevated MAP kinase activity is not a significant contributor to the H-Ras 12V effect. These data suggest that an additional Ras pathway, distinct from the well-characterized MAP kinase and Rac/Rho pathways known to be important for the transforming function of activated Ras, is primarily responsible for the inhibition of myogenesis by H-Ras 12V.

Functional Role of p38 Mitogen Activated Protein Kinase in Platelet Activation induced by a Thromboxane A2 Analogue and by 8-iso-prostaglandin F2 α

2002 ◽  
Vol 87 (05) ◽  
pp. 888-898 ◽  
Author(s):  
Stefania Gaino ◽  
Valeria Zuliani ◽  
Rosa Tommasoli ◽  
Donatella Benati ◽  
Riccardo Ortolani ◽  
...  
Keyword(s):  
Map Kinase ◽  
Platelet Activation ◽  
Tyrosine Kinases ◽  
Actin Polymerization ◽  
Shape Change ◽  
Specific Inhibitor ◽  
P38 Map Kinase ◽  
Mitogen Activated Protein Kinase ◽  
Mitogen Activated Protein ◽  
Kinase Phosphorylation

SummaryWe investigated similarities in the signaling pathways elicited by the F2 isoprostane 8-iso-PGF2α and by low doses of U46619 to induce platelet activation. Both 0.01-0.1 µmol/L U46619 and 0.01-1 µmol/L 8-isoPGF2α triggered shape change and filopodia extension, as well as adhesion to immobilized fibrinogen of washed platelets. At these doses the two platelet agonists failed to trigger secretion and aggregation, which were however induced by higher doses of U46619 (0.1-1 µmol/L). SB203580 (1-10 µmol/L), a specific inhibitor of the p38 mitogen activated protein (MAP) kinase blunted platelet shape change and adhesion induced by 0.05-1 µmol/L 8-iso-PGF2α and by 0.01 µmol/L U46619. These platelet responses were also inhibited by 20 µmol/L cytochalasin D, an inhibitor of actin polymerization, and 50 µmol/L piceatannol, an inhibitor of the Syk tyrosine kinases. Both 8-iso-PGF2α and U46619-induced p38 MAP kinase phosphorylation in suspended platelets and this was inhibited by piceatannol, indicating that Syk activation occurs upstream p38 MAP kinase phosphorylation. These findings suggest that the signaling pathway triggered by both 8-iso-PGF2α and low concentrations of U46619 to induce platelet adhesion and shape change implicates Syk, the p38 MAP kinase, and actin polymerization.

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