Unknown,Transcriptomics,Genomics,Proteomics

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Transcription profiling of Arabidopsis ARR2 mutants vs wild type

ABSTRACT: Phytohormones like ethylene and cytokinin are important regulators of plant growth and development. Perception of these hormones is accomplished by families of sensor histidine kinase-type receptors. Here, we identified the response regulator ARR2 as a signaling component functioning downstream of not only cytokinin receptors but also of the ethylene receptor ETR1. Transcriptome analyses suggest that ARR2 also participates in the regulation of several other signaling pathways. Further investigations indicate that hormone-initiated multi-step phosphorelais regulate the transcription factor activity of ARR2. The ETR1-dependent mechanism thereby creates a CTR1-independent ethylene signal transfer. From our data we propose that a two-component signaling network exists in higher plants that is predominantly responsible for fine-tuning and integration of a large number of signal transduction pathways.

ORGANISM(S): Arabidopsis thaliana

SUBMITTER: Uta Sweere

PROVIDER: E-MEXP-125 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Publications

The response regulator 2 mediates ethylene signalling and hormone signal integration in Arabidopsis.

Hass Claudia C Lohrmann Jens J Albrecht Verónica V Sweere Uta U Hummel Florian F Yoo Sang Dong SD Hwang Ildoo I Zhu Tong T Schäfer Eberhard E Kudla Jörg J Harter Klaus K

The EMBO journal 20040729 16

Hormones are important regulators of plant growth and development. In Arabidopsis, perception of the phytohormones ethylene and cytokinin is accomplished by a family of sensor histidine kinases including ethylene-resistant (ETR) 1 and cytokinin-response (CRE) 1. We identified the Arabidopsis response regulator 2 (ARR2) as a signalling component functioning downstream of ETR1 in ethylene signal transduction. Analyses of loss-of-function and ARR2-overexpressing lines as well as functional assays i ...[more]

PMID: 15282545

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Project description:Background: Diclofenac is a non-steroidal anti-inflammatory drug frequently found in the aquatic environment. Previous studies have reported histological changes in the liver, kidney and gills of fish at concentrations similar to those measured in treated sewage effluents (~1 µg/L). Analyses or predictions of blood plasma levels in fish allow a direct comparison with human therapeutic plasma levels, and may therefore be used to indicate a risk for pharmacological effects in fish. To relate internal exposure to a pharmacological interaction we therefore investigated global hepatic gene expression together with bioconcentration to blood plasma and liver of rainbow trout (Oncorhynchus mykiss) exposed to waterborne diclofenac. Results: At the highest exposure (81.5µg/L) the fish plasma concentration reached ~88% of the human therapeutic levels (Cmax) after two weeks. Using an oligonucleotide microarray followed by quantitative PCR we found extensive effects on hepatic gene expression at this concentration, and some genes were regulated down to the lowest concentration tested (1.6 µg/L) corresponding to ~1.5% of the human Cmax. Functional analysis of differentially expressed genes revealed effects on biological processes such as inflammation and immune response, in agreement with the expected mode of action of diclofenac. In contrast to some previously reported results, the bioconcentration factor was found to be stable (4.02±0.75 for blood plasma and 2.54±0.36 for liver) regardless of the water concentration. Conclusions: Hepatic gene expression is affected in fish at blood levels similar to and below the human Cmax. This adds confidence to the use of fish blood plasma levels to predict risks for pharmacological responses in fish. The microarray results indicate similarities in the mode of action of diclofenac between humans and fish. The identified set of regulated genes may contain useful exposure biomarkers to be used in complex exposure scenarios. Juvenile rainbow trout was exposed to waterborne diclofenac at a series of different concentrations for 14 days. A flow-through system was used for eight aquaria (two per concentration), each containing 12 trouts. Nominal exposure concentrations: 1µg/L, 10 µg/L, 100 µg/L and control. Total RNA for biotinylated aRNA synthesis was extracted from the liver. Samples of aRNA from two fish from the same aquarium were pooled before the assay. In total, four biochips were analyzed corresponding to 32 microarrays. As we used two aquaria per concentration, these 32 microarrays allowed the analyses of four aRNA pools (eight fish) per aquarium, which is equal to eight pools per concentration of diclofenac.

Project description:This is the single cell model for analysis of hormonal crosstalk in Arabidopsis described in the article: Modelling and experimental analysis of hormonal crosstalk in Arabidopsis. Liu J, Mehdi S, Topping J, Tarkowski P and Lindsey K. Mol Syst Biol. 2010 Jun 8;6:373; PmID: 20531403 , DOI: 10.1038/msb.2010.26 Abstract: An important question in plant biology is how genes influence the crosstalk between hormones to regulate growth. In this study, we model POLARIS (PLS) gene function and crosstalk between auxin, ethylene and cytokinin in Arabidopsis. Experimental evidence suggests that PLS acts on or close to the ethylene receptor ETR1, and a mathematical model describing possible PLS-ethylene pathway interactions is developed, and used to make quantitative predictions about PLS-hormone interactions. Modelling correctly predicts experimental results for the effect of the pls gene mutation on endogenous cytokinin concentration. Modelling also reveals a role for PLS in auxin biosynthesis in addition to a role in auxin transport. The model reproduces available mutants, and with new experimental data provides new insights into how PLS regulates auxin concentration, by controlling the relative contribution of auxin transport and biosynthesis and by integrating auxin, ethylene and cytokinin signalling. Modelling further reveals that a bell-shaped dose-response relationship between endogenous auxin and root length is established via PLS. This combined modelling and experimental analysis provides new insights into the integration of hormonal signals in plants. This model was originally created using Copasi and taken from the supplementary materials of the MSB article. It uses equation 5 for the auxin biosynthesis and was altered to also contain the reactions for ACC, IAA and cytokinine import. Different from the supplementary material, the parameters for the auxin synthesis, v2, are set to k2c = 0.01 uM and k2=0.2 uM_per_sec and for the WT PLS transcription k6=0.3 . To obtain the model described in the first table of the supplementary materials, set k2c=k2=0 and k6=0.9 . For the pls and PLSox mutants, k6 should be set to 0 and 0.45, respectively. This model originates from BioModels Database: A Database of Annotated Published Models. It is copyright (c) 2005-2010 The BioModels Team. For more information see the terms of use . To cite BioModels Database, please use Le Novère N., Bornstein B., Broicher A., Courtot M., Donizelli M., Dharuri H., Li L., Sauro H., Schilstra M., Shapiro B., Snoep J.L., Hucka M. (2006) BioModels Database: A Free, Centralized Database of Curated, Published, Quantitative Kinetic Models of Biochemical and Cellular Systems Nucleic Acids Res., 34: D689-D691.

Dataset Information

Transcription profiling of Arabidopsis ARR2 mutants vs wild type

Publications

The response regulator 2 mediates ethylene signalling and hormone signal integration in Arabidopsis.

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