Melatonin functions in priming of stomatal immunity in Panax notoginseng and Arabidopsis thaliana

2021 ◽  
Author(s):  
Qian Yang ◽  
Zhongping Peng ◽  
Wenna Ma ◽  
Siqi Zhang ◽  
Suyin Hou ◽  
...  

Abstract Melatonin (MT) plays important roles in plant disease response, but the mechanisms are largely unknown. Here, we show that MT functions in stomatal immunity in Panax notoginseng and Arabidopsis thaliana. Biochemical analyses showed that MT-induced stomatal closure plays a prominent role in preventing invasion of bacteria Pseudomonas syringe pv. tomato (Pst) DC3000 via activation of mitogen-activated protein kinase (MAPK) and NADPH oxidase-mediated reactive oxygen species production in P. notoginseng. The first putative phytomelatonin receptor 1 (PMTR1) is a plasma membrane protein required for perceiving MT signaling in stomatal closure and activation of MAPK. Biochemical and genetic tests found PMTR1 is essential for flg22- and MT-induced MAPK activation in a heterotrimeric GTP-binding protein Gα subunit GPA1-independent manner. GPA1 functions in the same genetic pathways of FLS2/BAK1 (Flagellin Sensing 2/Brassinosteroid Insensitive 1-associated kinase 1)- as well as PMTR1-mediated flg22 and MT signaling in stomatal closure. The stomata in pmtr1 are insensitive to MT and flg22, but the application of MT induces stomatal closure and reduces the bacterial growth in fls2 and bak1 plants, indicating that PMTR1 might be a downstream signaling component in FLS2- and BAK1-mediated stomatal immunity. In summary, our results (i) demonstrate that phytomelatonin functions in the priming of stomatal immunity and (ii) provide insights into the phytomelatonin signaling transduction pathway.

Blood ◽  
2008 ◽  
Vol 111 (9) ◽  
pp. 4511-4522 ◽  
Author(s):  
Florian Grebien ◽  
Marc A. Kerenyi ◽  
Boris Kovacic ◽  
Thomas Kolbe ◽  
Verena Becker ◽  
...  

Abstract Erythropoiesis requires erythropoietin (Epo) and stem cell factor (SCF) signaling via their receptors EpoR and c-Kit. EpoR, like many other receptors involved in hematopoiesis, acts via the kinase Jak2. Deletion of EpoR or Janus kinase 2 (Jak2) causes embryonic lethality as a result of defective erythropoiesis. The contribution of distinct EpoR/Jak2-induced signaling pathways (mitogen-activated protein kinase, phosphatidylinositol 3-kinase, signal transducer and activator of transcription 5 [Stat5]) to functional erythropoiesis is incompletely understood. Here we demonstrate that expression of a constitutively activated Stat5a mutant (cS5) was sufficient to relieve the proliferation defect of Jak2−/− and EpoR−/− cells in an Epo-independent manner. In addition, tamoxifen-induced DNA binding of a Stat5a–estrogen receptor (ER)* fusion construct enabled erythropoiesis in the absence of Epo. Furthermore, c-Kit was able to enhance signaling through the Jak2-Stat5 axis, particularly in lymphoid and myeloid progenitors. Although abundance of hematopoietic stem cells was 2.5-fold reduced in Jak2−/− fetal livers, transplantation of Jak2−/−-cS5 fetal liver cells into irradiated mice gave rise to mature erythroid and myeloid cells of donor origin up to 6 months after transplantation. Cytokine- and c-Kit pathways do not function independently of each other in hematopoiesis but cooperate to attain full Jak2/Stat5 activation. In conclusion, activated Stat5 is a critical downstream effector of Jak2 in erythropoiesis/myelopoiesis, and Jak2 functionally links cytokine- with c-Kit-receptor tyrosine kinase signaling.


Forests ◽  
2020 ◽  
Vol 11 (11) ◽  
pp. 1160
Author(s):  
Xinying Chen ◽  
Pengkai Wang ◽  
Fangfang Zhao ◽  
Lu Lu ◽  
Xiaofei Long ◽  
...  

To adapt and sense environmental perturbations, including a variety of biotic and abiotic stress conditions, plants have developed disparate regulatory pathways. Mitogen-activated protein kinase (MAPK or MPK) signaling cascades are found widespread across the eukaryotic kingdoms of life. In plants, they may regulate signaling pathways aimed at resisting the stressful effects of low temperature, salt damage, drought, touch, and mechanical damage. To date, no conclusive studies into Liriodendron chinense (Hemsl.) Sarg MPK-related stress resistance signaling have been performed. In our study, we cloned three homologous L. chinense MAP kinase kinase family genes: LcMKK2, LcMKK4, and LcMKK6. LcMKK2 and LcMKK6 have their highest expression level in the root, while LcMKK4 is highly expressed in the stem. LcMKK2 showed upregulation in response to salt and cold stress conditions in L. chinense. To further analyze its gene function, we overexpressed LcMKK2 in wild-type Arabidopsis thaliana (L.) Heynh. and obtained transgenic plants. Overexpression of LcMKK2 caused a significant reduction in plant mortality (from 96% to 70%) in response to a 7-day 200 mM NaCl treatment. Therefore, we conclude that LcMKK2 is involved in a signaling response to salt stress, and it could thus prove an effective target gene for breeding strategies to improve Liriodendron salt tolerance.


Planta ◽  
2019 ◽  
Vol 250 (4) ◽  
pp. 1177-1189 ◽  
Author(s):  
Jesús Salvador López-Bucio ◽  
Guadalupe Jessica Salmerón-Barrera ◽  
Gustavo Ravelo-Ortega ◽  
Javier Raya-González ◽  
Patricia León ◽  
...  

2013 ◽  
Vol 68 (3-4) ◽  
pp. 148-154 ◽  
Author(s):  
Hui Yang ◽  
Shu Yuan ◽  
Yi Luo ◽  
Ji Huang ◽  
Yang-Er Chen ◽  
...  

Plant hormones play pivotal roles as signals of plant-pathogen interactions. Here, we report that exogenous application of salicylic acid (SA), jasmonic acid (JA), ethephon (ETH), and abscisic acid (ABA) can reduce Turnip crinkle virus (TCV) accumulation in systemic leaves of Arabidopsis thaliana during early infection. SA and ABA are more efficient and confer a longer-lasting resistance against TCV than JA and ETH, and the plant hormones interact in effecting the plant defence. Synergistic actions of SA and JA, and SA and ET, and an antagonistic action of SA and ABA have been observed in the Arabidopsis-TCV interaction. ABA can down-regulate the expression of the pathogenesis-related genes PR1 and PDF1.2, and compared to the wild type, it drastically reduces TCV accumulation in NahG transgenic plants and the eds5-p1 mutant, both of which do not accumulate SA. This indicates that SA signaling negatively regulates the ABA-mediated defence. ABA-induced resistance against TCV is independent of SA. We also found that mitogen-activated protein kinase 5 (MPK5) may be involved in ABA-mediated defence. These results indicate that Arabidopsis can activate distinct signals to inhibit virus accumulation. Cooperative or antagonistic crosstalk between them is pivotal for establishing disease resistance. These results show potential to enhance the plant defence against viruses by manipulating diverse hormones.


2019 ◽  
Vol 20 (19) ◽  
pp. 4779 ◽  
Author(s):  
Jeanne K. DuShane ◽  
Colleen L. Mayberry ◽  
Michael P. Wilczek ◽  
Sarah L. Nichols ◽  
Melissa S. Maginnis

JC polyomavirus (JCPyV), a ubiquitous human pathogen, is the etiological agent of the fatal neurodegenerative disease progressive multifocal leukoencephalopathy (PML). Like most viruses, JCPyV infection requires the activation of host-cell signaling pathways in order to promote viral replication processes. Previous works have established the necessity of the extracellular signal-regulated kinase (ERK), the terminal core kinase of the mitogen-activated protein kinase (MAPK) cascade (MAPK-ERK) for facilitating transcription of the JCPyV genome. However, the underlying mechanisms by which the MAPK-ERK pathway becomes activated and induces viral transcription are poorly understood. Treatment of cells with siRNAs specific for Raf and MAP kinase kinase (MEK) targets proteins in the MAPK-ERK cascade, significantly reducing JCPyV infection. MEK, the dual-specificity kinase responsible for the phosphorylation of ERK, is phosphorylated at times congruent with early events in the virus infectious cycle. Moreover, a MAPK-specific signaling array revealed that transcription factors downstream of the MAPK cascade, including cMyc and SMAD4, are upregulated within infected cells. Confocal microscopy analysis demonstrated that cMyc and SMAD4 shuttle to the nucleus during infection, and nuclear localization is reduced when ERK is inhibited. These findings suggest that JCPyV induction of the MAPK-ERK pathway is mediated by Raf and MEK and leads to the activation of downstream transcription factors during infection. This study further defines the role of the MAPK cascade during JCPyV infection and the downstream signaling consequences, illuminating kinases as potential therapeutic targets for viral infection.


2013 ◽  
Vol 394 (9) ◽  
pp. 1145-1161 ◽  
Author(s):  
Christoph Garbers ◽  
Jürgen Scheller

Abstract The pleiotropic physiological functions of interleukin (IL-)6 type cytokines range from embryonic development and tissue homoeostasis to neuronal development and T cell differentiation. In contrast, imbalance of the well-controlled cytokine signaling network leads to chronic inflammatory diseases and cancer. IL-6 and IL-11 both signal through a homodimer of the ubiquitously expressed β-receptor glycoprotein 130 (gp130). Specificity is gained through an individual IL-6/IL-11 α-receptor, which does not directly participate in signal transduction, although the initial cytokine binding event to the α-receptor leads to the final complex formation with the β-receptors. Both cytokines activate the same downstream signaling pathways, which are predominantly the mitogen-activated protein kinase (MAPK)-cascade and the Janus kinase/signal transducer and activator of transcription (Jak/STAT) pathway. However, recent studies have highlighted divergent roles of the two related cytokines. Here, we will discuss how the biochemical similarities are translated into unique and non-redundant functions of IL-6 and IL-11 in vivo and illustrate strategies for cytokine-specific therapeutic intervention.


2013 ◽  
Vol 31 (15_suppl) ◽  
pp. e11560-e11560
Author(s):  
Jean-Louis Merlin ◽  
Alexandre Harle ◽  
Maeva Lion ◽  
Anne-Sophie Chrétien ◽  
Carole Ramacci ◽  
...  

e11560 Background: P38 kinases are members of the mitogen-activated protein kinase (MAPK) family. In breast cancers MAPK, as well as PI3 kinase-AKT pathway signaling proteins have major implication in molecular oncogenesis and are extensively investigated as putative targets for therapy. The present study reports the investigation of the expression of P38MAPK and its phosphorylated form (p-P38MAPK) in clinical specimens of invasive breast carcinomas in relation with estrogen receptor and HER2 expression, as well as MAPK and PI3K signaling phosphorylated proteins. Methods: The expression of P38MAPK and p-P38MAPK as well as p-AKT, p-GSK3β, p-S6 kinase, p-MEK1, p-ERK1/2 were semi-quantitatively assessed using multiplex bead immuno-assay. The analyses were performed retrospectively in frozen specimens from 46 invasive breast tumors classified according to estrogen receptor (ER) and HER2 status. Results: All specimens were taken at diagnosis and validated for tumor content >50%. Twenty-nine were ER+, 17 were HER2+, 10 were triple negative (TN) tumors. Analyses were performed in triplicate from total protein extracts and were achievable in all specimens. P38MAPK was found to be expressed in all tumor specimen and significantly (P=0.002) overexpressed in ER+ tumors. P38MAPK was lower in TN tumors than in all others. The median expression of phosphorylated-P38MAPK was also higher in ER+ than in ER- tumors and lower in TN tumors than in all others. HER2 status had no influence on P38MAPK and p-P38MAPK expression. No variation in the phosphorylation rate of P38MAPK was observed in relation with ER, HER2 or TN status. Significantly higher (P=0.0048) expression of p-AKT tumors was observed in HER2+ tumors. No significant difference in p-MEK1, p-GSK3β and p-S6K expression was evidenced in any other comparisons based on ER and HER2 expression subtypes. Conclusions: Investigation of the expression of multiple phosphorylated signaling proteins can be used as molecular biomarkers for personalized targeted therapy. In ER+ invasive breast cancer, the overexpression of P38MAPK could serve as biomarker for evaluation of P38MAPK inhibitors.


2013 ◽  
Vol 202 (2) ◽  
pp. 261-276 ◽  
Author(s):  
Todd Schoborg ◽  
Ryan Rickels ◽  
Josh Barrios ◽  
Mariano Labrador

Chromatin insulators assist in the formation of higher-order chromatin structures by mediating long-range contacts between distant genomic sites. It has been suggested that insulators accomplish this task by forming dense nuclear foci termed insulator bodies that result from the coalescence of multiple protein-bound insulators. However, these structures remain poorly understood, particularly the mechanisms triggering body formation and their role in nuclear function. In this paper, we show that insulator proteins undergo a dramatic and dynamic spatial reorganization into insulator bodies during osmostress and cell death in a high osmolarity glycerol–p38 mitogen-activated protein kinase–independent manner, leading to a large reduction in DNA-bound insulator proteins that rapidly repopulate chromatin as the bodies disassemble upon return to isotonicity. These bodies occupy distinct nuclear territories and contain a defined structural arrangement of insulator proteins. Our findings suggest insulator bodies are novel nuclear stress foci that can be used as a proxy to monitor the chromatin-bound state of insulator proteins and provide new insights into the effects of osmostress on nuclear and genome organization.


2014 ◽  
Vol 35 (5) ◽  
pp. 778-788 ◽  
Author(s):  
Ze-Yan Zhang ◽  
Shang-Ze Li ◽  
Hui-Hui Zhang ◽  
Qu-Ran Wu ◽  
Jun Gong ◽  
...  

Interleukin-1β (IL-1β) is a key proinflammatory cytokine that initiates several signaling cascades, including those involving CCAAT/enhancer binding proteins (C/EBPs). The mechanism by which IL-1β propagates a signal that activates C/EBP has remained elusive. Nemo-like kinase (NLK) is a mitogen-activated protein kinase (MAPK)-like kinase associated with many pathways and phenotypes that are not yet well understood. Using a luciferase reporter screen, we found that IL-1β-induced C/EBP activation was positively regulated by NLK. Overexpression of NLK activated C/EBP and potentiated IL-1β-triggered C/EBP activation, whereas knockdown or knockout of NLK had the opposite effect. NLK interacted with activating transcription factor 5 (ATF5) and inhibited the proteasome-dependent degradation of ATF5 in a kinase-independent manner. Consistently, NLK deficiency resulted in decreased levels of ATF5. NLK cooperated with ATF5 to activate C/EBP, whereas NLK could not activate C/EBP upon knockdown of ATF5. Moreover, TAK1, a downstream effector of IL-1β that acts upstream of NLK, mimicked the ability of NLK to stabilize ATF5 and activate C/EBP. Thus, our findings reveal the TAK1-NLK pathway as a novel regulator of basal or IL-1β-triggered C/EBP activation though stabilization of ATF5.


1993 ◽  
Vol 90 (23) ◽  
pp. 10952-10956 ◽  
Author(s):  
R H Chen ◽  
C Abate ◽  
J Blenis

Phosphorylation of the C terminus of c-Fos has been implicated in serum response element-mediated repression of c-fos transcription after its induction by serum growth factors. The growth-regulated enzymes responsible for this phosphorylation in early G1 phase of the cell cycle and the sites of phosphorylation have not been identified. We now provide evidence that two growth-regulated, nucleus- and cytoplasm-localized protein kinases, 90-kDa ribosomal S6 kinase (RSK) and mitogen-activated protein kinase (MAP kinase), contribute to the serum-induced phosphorylation of c-Fos. The major phosphopeptides derived from biosynthetically labeled c-Fos correspond to phosphopeptides generated after phosphorylation of c-Fos in vitro with both RSK and MAP kinase. The phosphorylation sites identified for RSK (Ser-362) and MAP kinase (Ser-374) are in the transrepression domain. Cooperative phosphorylation at these sites by both enzymes was observed in vitro and reflected in vivo by the predominance of the peptide phosphorylated on both sites, as opposed to singly phosphorylated peptides. This study suggests a role for nuclear RSK and MAP kinase in modulating newly synthesized c-Fos phosphorylation and downstream signaling.


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