scholarly journals Proline Accumulation and AtP5CS2 Gene Activation Are Induced by Plant-Pathogen Incompatible Interactions in Arabidopsis

2004 ◽  
Vol 17 (4) ◽  
pp. 343-350 ◽  
Author(s):  
Georgina Fabro ◽  
Izabella Kovács ◽  
Valeria Pavet ◽  
László Szabados ◽  
María E. Alvarez
Keyword(s):  
Pseudomonas Syringae ◽  
Plant Pathogen ◽  
Transcriptional Activation ◽  
Gene Activation ◽  
Protective Role ◽  
Leaf Tissues ◽  
Compatible Osmolyte ◽  
Plant Pathogen Interactions ◽  
Incompatible Interactions

Accumulation of free L-proline (Pro) is a typical stress response incited by osmotic injuries in plants and microorganisms. Although the protective role of Pro in osmotic stress is not well understood, it is thought to function as compatible osmolyte or as a scavenger of reactive oxygen species (ROS). Here we show that, in Arabidopsis thaliana, Pro biosynthesis can be activated by incompatible plant—pathogen interactions triggering a hypersensitive response (HR). Pro accumulates in leaf tissues treated with Pseudomonas syringae pv. tomato avirulent strains (avrRpt2 and avrRpm1) but remains unchanged in leaves infected with isogenic virulent bacteria. Incompatible interactions lead to transcriptional activation of AtP5CS2, but not AtP5CS1, encoding the rate limiting enzyme in Pro biosynthesis pyrroline-5-carboxylate synthase (P5CS). AtP5CS2:GUS and AtP5CS2:LUC transgenes were induced inside and around the HR lesions produced by avirulent Pseudomonas spp. in transgenic plants. Pro accumulation was faster and stronger when stimulated by avrRpm1 than by avrRpt2, and was compromised in the low-salicylic acid plants NahG and eds5 when signaled through the RPS2-dependent pathway. In addition, Pro content and AtP5CS2 expression were enhanced by ROS in wild-type plants, suggesting that ROS may function as an intermediate signal in AtP5CS2-mediated Pro accumulation.

scholarly journals Evidence for a Bigenic Chromatin Subdomain in Regulation of the Fetal-to-Adult Hemoglobin Switch

2008 ◽  
Vol 29 (6) ◽  
pp. 1635-1648 ◽  
Author(s):  
Hugues Beauchemin ◽  
Marie Trudel
Keyword(s):  
Transcriptional Activation ◽  
Gene Activation ◽  
Dna Demethylation ◽  
Open Chromatin ◽  
Chromosome Conformation ◽  
Hemoglobin Switching ◽  
Switching Patterns ◽  
Adult Hemoglobin ◽  
Globin Promoter

ABSTRACT During development, human β-globin locus regulation undergoes two critical switches, the embryonic-to-fetal and fetal-to-adult hemoglobin switches. To define the role of the fetal Aγ-globin promoter in switching, human β-globin-YAC transgenic mice were produced with the Aγ-globin promoter replaced by the erythroid porphobilinogen deaminase (PBGD) promoter (PBGDAγ-YAC). Activation of the stage-independent PBGDAγ-globin strikingly stimulated native Gγ-globin expression at the fetal and adult stages, identifying a fetal gene pair or bigenic cooperative mechanism. This impaired fetal silencing severely suppressed both δ- and β-globin expression in PBGDAγ-YAC mice from fetal to neonatal stages and altered kinetics and delayed switching of adult β-globin. This regulation evokes the two human globin switching patterns in the mouse. Both patterns of DNA demethylation and chromatin immunoprecipitation analysis correlated with gene activation and open chromatin. Locus control region (LCR) interactions detected by chromosome conformation capture revealed distinct spatial fetal and adult LCR bigenic subdomains. Since both intact fetal promoters are critical regulators of fetal silencing at the adult stage, we concluded that fetal genes are controlled as a bigenic subdomain rather than a gene-autonomous mechanism. Our study also provides evidence for LCR complex interaction with spatial fetal or adult bigenic functional subdomains as a niche for transcriptional activation and hemoglobin switching.

scholarly journals The Role of Auxin-Cytokinin Antagonism in Plant-Pathogen Interactions

2012 ◽  
Vol 8 (11) ◽  
pp. e1003026 ◽  
Author(s):  
Muhammad Naseem ◽  
Thomas Dandekar
Keyword(s):  
Plant Pathogen ◽  
Plant Pathogen Interactions

FGF21 prevents low protein diet-induced renal inflammation in aged mice

2021 ◽  
Author(s):  
Han Fang ◽  
Sujoy Ghosh ◽  
Landon Sims ◽  
Kirsten P. Stone ◽  
Cristal M Hill ◽  
...  
Keyword(s):  
Transcriptional Activation ◽  
Renal Damage ◽  
Protective Role ◽  
Wild Type ◽  
Kidney Weight ◽  
Albumin Creatinine Ratio ◽  
Low Protein ◽  
The Impact ◽  
Protein Diets

Low protein diets extend lifespan through a comprehensive improvement in metabolic health across multiple tissues and organs. Many of these metabolic responses to protein restriction are secondary to transcriptional activation and release of FGF21 from the liver. However, the effects of a low protein (LP) diet on the kidney in the context of aging has not been examined. Therefore, the goal of the current study was to investigate the impact of chronic consumption of a LP diet on the kidney in aging mice lacking FGF21. Wild type (WT, C57BL/6J) and FGF21 KO mice were fed a normal protein (NP, 20% casein) or a LP (5% casein) diet ad libitum from 3 to19 months of age. The LP diet led to a decrease in kidney weight and urinary albumin/creatinine ratio in both WT and FGF21 KO mice. Although the LP diet produced only mild fibrosis and infiltration of leukocytes in WT kidneys, the effects were significantly exacerbated by the absence of FGF21. Accordingly, transcriptomic analysis showed that inflammation-related pathways were significantly enriched and upregulated in response to LP diet in FGF21 KO but not WT mice. Collectively, these data demonstrate that the LP diet negatively affected the kidney during aging, but in the absence of FGF21, the LP diet-induced renal damage and inflammation were significantly worse, indicating a protective role of FGF21 in the kidney.

scholarly journals Antioxidant Functions of the Aryl Hydrocarbon Receptor

2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
Cornelia Dietrich
Keyword(s):  
Polycyclic Aromatic Hydrocarbons ◽  
Aryl Hydrocarbon Receptor ◽  
Aromatic Hydrocarbons ◽  
Transcriptional Activation ◽  
Antioxidant Response ◽  
Protective Role ◽  
Helix Loop Helix ◽  
Aryl Hydrocarbon ◽  
Polycyclic Aromatic

The aryl hydrocarbon receptor (AhR) is a transcription factor belonging to the basic helix-loop-helix/PER-ARNT-SIM family. It is activated by a variety of ligands, such as environmental contaminants like polycyclic aromatic hydrocarbons or dioxins, but also by naturally occurring compounds and endogenous ligands. Binding of the ligand leads to dimerization of the AhR with aryl hydrocarbon receptor nuclear translocator (ARNT) and transcriptional activation of several xenobiotic phase I and phase II metabolizing enzymes. It is generally accepted that the toxic responses of polycyclic aromatic hydrocarbons, dioxins, and structurally related compounds are mediated by activation of the AhR. A multitude of studies indicate that the AhR operates beyond xenobiotic metabolism and exerts pleiotropic functions. Increasing evidence points to a protective role of the AhR against carcinogenesis and oxidative stress. Herein, I will highlight data demonstrating a causal role of the AhR in the antioxidant response and present novel findings on potential AhR-mediated antioxidative mechanisms.

scholarly journals Pseudomonas syringae Evades Host Immunity by Degrading Flagellin Monomers with Alkaline Protease AprA

2014 ◽  
Vol 27 (7) ◽  
pp. 603-610 ◽  
Author(s):  
Michiel J. C. Pel ◽  
Anja J. H. van Dijken ◽  
Bart W. Bardoel ◽  
Michael F. Seidl ◽  
Sjoerd van der Ent ◽  
...  
Keyword(s):  
Pseudomonas Syringae ◽  
Alkaline Protease ◽  
Bacterial Species ◽  
Gene Activation ◽  
Ectopic Expression ◽  
Host Immunity ◽  
Wild Type ◽  
Knockout Mutant ◽  
Inhibitory Peptide

Bacterial flagellin molecules are strong inducers of innate immune responses in both mammals and plants. The opportunistic pathogen Pseudomonas aeruginosa secretes an alkaline protease called AprA that degrades flagellin monomers. Here, we show that AprA is widespread among a wide variety of bacterial species. In addition, we investigated the role of AprA in virulence of the bacterial plant pathogen P. syringae pv. tomato DC3000. The AprA-deficient DC3000 ΔaprA knockout mutant was significantly less virulent on both tomato and Arabidopsis thaliana. Moreover, infiltration of A. thaliana Col-0 leaves with DC3000 ΔaprA evoked a significantly higher level of expression of the defense-related genes FRK1 and PR-1 than did wild-type DC3000. In the flagellin receptor mutant fls2, pathogen virulence and defense-related gene activation did not differ between DC3000 and DC3000 ΔaprA. Together, these results suggest that AprA of DC3000 is important for evasion of recognition by the FLS2 receptor, allowing wild-type DC3000 to be more virulent on its host plant than AprA-deficient DC3000 ΔaprA. To provide further evidence for the role of DC3000 AprA in host immune evasion, we overexpressed the AprA inhibitory peptide AprI of DC3000 in A. thaliana to counteract the immune evasive capacity of DC3000 AprA. Ectopic expression of aprI in A. thaliana resulted in an enhanced level of resistance against wild-type DC3000, while the already elevated level of resistance against DC3000 ΔaprA remained unchanged. Together, these results indicate that evasion of host immunity by the alkaline protease AprA is important for full virulence of strain DC3000 and likely acts by preventing flagellin monomers from being recognized by its cognate immune receptor.

The role of chitin detection in plant–pathogen interactions

2011 ◽  
Vol 13 (14-15) ◽  
pp. 1168-1176 ◽  
Author(s):  
Anja Kombrink ◽  
Andrea Sánchez-Vallet ◽  
Bart P.H.J. Thomma
Keyword(s):  
Plant Pathogen ◽  
Plant Pathogen Interactions
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