Controlled nuclear import of the transcription factor NTL6 reveals a cytoplasmic role of SnRK2.8 in the drought-stress response

2012 ◽  
Vol 448 (3) ◽  
pp. 353-363 ◽  
Author(s):  
Mi Jung Kim ◽  
Mi-Jeong Park ◽  
Pil Joon Seo ◽  
Jin-Su Song ◽  
Hie-Joon Kim ◽  
...  

Controlled proteolytic activation of membrane-anchored transcription factors provides an adaptation strategy that guarantees rapid transcriptional responses to abrupt environmental stresses in both animals and plants. NTL6 is a plant-specific NAC [NAM/ATAF1/2/CUC2] transcription factor that is expressed as a dormant plasma membrane-associated form in Arabidopsis. Proteolytic processing of NTL6 is triggered by abiotic stresses and ABA (abscisic acid). In the present study, we show that NTL6 is linked directly with SnRK (Snf1-related protein kinase) 2.8-mediated signalling in inducing a drought-resistance response. SnRK2.8 phosphorylates NTL6 primarily at Thr142. NTL6 phosphorylation by SnRK2.8 is required for its nuclear import. Accordingly, a mutant NTL6 protein, in which Thr142 was mutated to an alanine, was poorly phosphorylated and failed to enter the nucleus. In accordance with the role of SnRK2.8 in drought-stress signalling, transgenic plants overproducing either NTL6 or its active form 6ΔC (35S:NTL6 and 35S:6ΔC) exhibited enhanced resistance to water-deficit conditions such as those overproducing SnRK2.8 (35S:SnRK2.8). In contrast, NTL6 RNAi (RNA interference) plants were susceptible to dehydration as observed in the SnRK2.8-deficient snrk2.8-1 mutant. Furthermore, the dehydration-resistant phenotype of 35S:NTL6 transgenic plants was compromised in 35S:NTL6 X snrk2.8-1 plants. These observations indicate that SnRK2.8-mediated protein phosphorylation, in addition to a proteolytic processing event, is important for NTL6 function in inducing a drought-resistance response.

2019 ◽  
Vol 20 (12) ◽  
pp. 3077 ◽  
Author(s):  
Elizabeta Madzharova ◽  
Philipp Kastl ◽  
Fabio Sabino ◽  
Ulrich auf dem Keller

Due to their capacity to process different proteins of the extracellular matrix (ECM), matrix metalloproteinases (MMPs) were initially described as a family of secreted proteases, functioning as main ECM regulators. However, through proteolytic processing of various biomolecules, MMPs also modulate intra- and extracellular pathways and networks. Thereby, they are functionally implicated in the regulation of multiple physiological and pathological processes. Consequently, MMP activity is tightly regulated through a combination of epigenetic, transcriptional, and post-transcriptional control of gene expression, proteolytic activation, post-translational modifications (PTMs), and extracellular inhibition. In addition, MMPs, their substrates and ECM binding partners are frequently modified by PTMs, which suggests an important role of PTMs in modulating the pleiotropic activities of these proteases. This review summarizes the recent progress towards understanding the role of PTMs (glycosylation, phosphorylation, glycosaminoglycans) on the activity of several members of the MMP family.


Plants ◽  
2019 ◽  
Vol 8 (7) ◽  
pp. 201 ◽  
Author(s):  
María José López-Galiano ◽  
Inmaculada García-Robles ◽  
Ana I. González-Hernández ◽  
Gemma Camañes ◽  
Begonya Vicedo ◽  
...  

In a scenario of global climate change, water scarcity is a major threat for agriculture, severely limiting crop yields. Therefore, alternatives are urgently needed for improving plant adaptation to drought stress. Among them, gene expression reprogramming by microRNAs (miRNAs) might offer a biotechnologically sound strategy. Drought-responsive miRNAs have been reported in many plant species, and some of them are known to participate in complex regulatory networks via their regulation of transcription factors involved in water stress signaling. We explored the role of miR159 in the response of Solanum lycopersicum Mill. plants to drought stress by analyzing the expression of sly-miR159 and its target SlMYB transcription factor genes in tomato plants of cv. Ailsa Craig grown in deprived water conditions or in response to mechanical damage caused by the Colorado potato beetle, a devastating insect pest of Solanaceae plants. Results showed that sly-miR159 regulatory function in the tomato plants response to distinct stresses might be mediated by differential stress-specific MYB transcription factor targeting. sly-miR159 targeting of SlMYB33 transcription factor transcript correlated with accumulation of the osmoprotective compounds proline and putrescine, which promote drought tolerance. This highlights the potential role of sly-miR159 in tomato plants’ adaptation to water deficit conditions.


2019 ◽  
Vol 116 (20) ◽  
pp. 9893-9902 ◽  
Author(s):  
Christopher M. Uyehara ◽  
Daniel J. McKay

The ecdysone pathway was among the first experimental systems employed to study the impact of steroid hormones on the genome. In Drosophila and other insects, ecdysone coordinates developmental transitions, including wholesale transformation of the larva into the adult during metamorphosis. Like other hormones, ecdysone controls gene expression through a nuclear receptor, which functions as a ligand-dependent transcription factor. Although it is clear that ecdysone elicits distinct transcriptional responses within its different target tissues, the role of its receptor, EcR, in regulating target gene expression is incompletely understood. In particular, EcR initiates a cascade of transcription factor expression in response to ecdysone, making it unclear which ecdysone-responsive genes are direct EcR targets. Here, we use the larval-to-prepupal transition of developing wings to examine the role of EcR in gene regulation. Genome-wide DNA binding profiles reveal that EcR exhibits widespread binding across the genome, including at many canonical ecdysone response genes. However, the majority of its binding sites reside at genes with wing-specific functions. We also find that EcR binding is temporally dynamic, with thousands of binding sites changing over time. RNA-seq reveals that EcR acts as both a temporal gate to block precocious entry to the next developmental stage as well as a temporal trigger to promote the subsequent program. Finally, transgenic reporter analysis indicates that EcR regulates not only temporal changes in target enhancer activity but also spatial patterns. Together, these studies define EcR as a multipurpose, direct regulator of gene expression, greatly expanding its role in coordinating developmental transitions.


2006 ◽  
Vol 26 (6) ◽  
pp. 2441-2455 ◽  
Author(s):  
Laurent Sansregret ◽  
Brigitte Goulet ◽  
Ryoko Harada ◽  
Brian Wilson ◽  
Lam Leduy ◽  
...  

ABSTRACT The CDP/Cux transcription factor was previously found to acquire distinct DNA binding and transcriptional properties following a proteolytic processing event that takes place at the G1/S transition of the cell cycle. In the present study, we have investigated the role of the CDP/Cux processed isoform, p110, in cell cycle progression. Populations of cells stably expressing p110 CDP/Cux displayed a faster division rate and reached higher saturation density than control cells carrying the empty vector. p110 CDP/Cux cells reached the next S phase faster than control cells under various experimental conditions: following cell synchronization in G0 by growth factor deprivation, synchronization in S phase by double thymidine block treatment, or enrichment in G2 by centrifugal elutriation. In each case, duration of the G1 phase was shortened by 2 to 4 h. Gene inactivation confirmed the role of CDP/Cux as an accelerator of cell cycle progression, since mouse embryo fibroblasts obtained from Cutl1z/z mutant mice displayed a longer G1 phase and proliferated more slowly than their wild-type counterparts. The delay to enter S phase persisted following immortalization by the 3T3 protocol and transformation with H-RasV12. Moreover, CDP/Cux inactivation hindered both the formation of foci on a monolayer and tumor growth in mice. At the molecular level, expression of both cyclin E2 and A2 was increased in the presence of p110 CDP/Cux and decreased in its absence. Overall, these results establish that p110 CDP/Cux functions as a cell cycle regulator that accelerates entry into S phase.


2010 ◽  
Vol 427 (3) ◽  
pp. 359-367 ◽  
Author(s):  
Pil Joon Seo ◽  
Mi Jung Kim ◽  
Jin-Su Song ◽  
Youn-Sung Kim ◽  
Hie-Joon Kim ◽  
...  

Changes in membrane fluidity are the earliest cellular events that occur in plant cells upon exposure to cold. This subsequently triggers physiological processes, such as calcium influx and reorganization of actin cytoskeletons, and induces expression of cold-responsive genes. The plasma-membrane-anchored NAC (NAM/ATAF/CUC) transcription factor NTL6 is of particular interest. Cold triggers proteolytic activation of the dormant NTL6 protein, which in turn elicits pathogen-resistance responses by inducing a small group of cold-inducible PR (pathogenesis-related) genes in Arabidopsis. In the present study, we show that proteolytic processing of NTL6 is regulated by cold-induced remodelling of membrane fluidity. NTL6 processing was stimulated rapidly by cold. The protein stability of NTL6 was also enhanced by cold. The effects of cold on NTL6 processing and protein stability were significantly reduced in cold-acclimatized plants, supporting the regulation of NTL6 processing by membrane fluidity. Consistent with this, although NTL6 processing was stimulated by pharmacological agents that reduce membrane fluidity and thus mimic cold, it was inhibited when plants were treated with a 18:3 unsaturated fatty acid, linolenic acid. In addition, the pattern of NTL6 processing was changed in Arabidopsis mutants with altered membrane lipid compositions. Assays employing chemicals that inhibit activities of the proteasome and proteases showed that NTL6 processing occurs via the regulated intramembrane proteolysis mechanism. Interestingly, a metalloprotease inhibitor blocked the NTL6 processing. These observations indicate that a metalloprotease activity is responsible for NTL6 processing in response to cold-induced changes in membrane fluidity.


2019 ◽  
Author(s):  
Christopher M. Uyehara ◽  
Daniel J. McKay

ABSTRACTThe ecdysone pathway was amongst the first experimental systems employed to study the impact of steroid hormones on the genome. In Drosophila and other insects, ecdysone coordinates developmental transitions, including wholesale transformation of the larva into the adult during metamorphosis. Like other hormones, ecdysone controls gene expression through a nuclear receptor, which functions as a ligand-dependent transcription factor. Although it is clear that ecdysone elicits distinct transcriptional responses within its different target tissues, the role of its receptor, EcR, in regulating target gene expression is incompletely understood. In particular, EcR initiates a cascade of transcription factor expression in response to ecdysone, making it unclear which ecdysone-responsive genes are direct EcR targets. Here, we use the larval-to-prepupal transition of developing wings to examine the role of EcR in gene regulation. Genome-wide DNA binding profiles reveal that EcR exhibits widespread binding across the genome, including at many canonical ecdysone-response genes. However, the majority of its binding sites reside at genes with wing-specific functions. We also find that EcR binding is temporally dynamic, with thousands of binding sites changing over time. RNA-seq reveals that EcR acts as both a temporal gate to block precocious entry to the next developmental stage as well as a temporal trigger to promote the subsequent program. Finally, transgenic reporter analysis indicates that EcR regulates not only temporal changes in target enhancer activity but also spatial patterns. Together, these studies define EcR as a multipurpose, direct regulator of gene expression, greatly expanding its role in coordinating developmental transitions.SIGNIFICANCENuclear receptors (NRs) are sequence-specific DNA binding proteins that act as intracellular receptors for small molecules such as hormones. Prior work has shown that NRs function as ligand-dependent switches that initiate a cascade of gene expression changes. The extent to which NRs function as direct regulators of downstream genes in these hierarchies remains incompletely understood. Here, we study the role of the NR EcR in metamorphosis of the Drosophila wing. We find that EcR directly regulates many genes at the top of the hierarchy as well as at downstream genes. Further, we find that EcR binds distinct sets of target genes at different developmental times. This work helps inform how hormones elicit tissue- and temporal-specific responses in target tissues.


Cell ◽  
1991 ◽  
Vol 66 (4) ◽  
pp. 743-758 ◽  
Author(s):  
Thomas Moll ◽  
Graham Tebb ◽  
Uttam Surana ◽  
Helmut Robitsch ◽  
Kim Nasmyth

2020 ◽  
Author(s):  
Youzhi Zhang ◽  
Yaping Li ◽  
Muhammad Jawad Hassan ◽  
Zhou Li ◽  
Yan Peng

Abstract Auxin plays an important role in regulating plant development. To idenfity what effects IAA has in white clover under drought stress and how IAA regulates white clover response to drought. Relative water content, chlorophyll content, six phytohormones content, expression of gene-related to IAA signal perception and synthesis, transcription factor genes related to drought-resistance and senescence genes were investigated in white clover pretreated with 1µM exogenous IAA or 100µM L-AOPP (inhibitor of IAA synthesis) under 15% polyethylene glycol-6000 (PEG-6000). Compared to control, drought stress significantly diminished stem dry weight (g/10 plant), relative water content (RWC, %) and total chlorophyll content (Chl, mg/g). Exogenous IAA significantly increased RWC and Chl, however, L-AOPP decreased stem dry weight, RWC and Chl compared with direct drought treatment. Besides that, compared with direct drought set, exogenous IAA significantly improved ABA content and JA content, up-regulated expression levels of some auxin-responsive genes ( GH3.1 , GH3.9 , IAA8 ) , transcription factor genes ( bZIP11 , DREB2 , MYB14 , MYB48 , WRKY2 , WRKY56 , WRKY108715 ) related to drought-resistance and drought resistance gene ( RD22 ). Meanwhile, exogenous IAA down-regulated expression levels of several auxin-responsive genes ( GH3.3 , GH3.6 , IAA27 ) and leaf senescence genes ( SAG101 and SAG102 ). Contrarily, L-AOPP significantly reduced ABA, GA3 and JA content, down-regulated expression levels of GH3.1 , GH3.9 , IAA8 , bZIP11 , DREB2 , MYB14 , MYB48 , WRKY2 , WRKY56 , WRKY108715 , ERD and RD22 , and up-regulated expression levels of SAG101 and SAG102 . Collectively, these data suggested a positive role of exogenous IAA in alleviating drought damage through many involved physiological processes in white clover.


2014 ◽  
Vol 50 (No. 4) ◽  
pp. 247-261 ◽  
Author(s):  
K. Kosová ◽  
P. Vítámvás ◽  
M.O. Urban ◽  
J. Kholová ◽  
I.T. Prášil

Drought represents the most devastating abiotic stress factor worldwide. It severely limits plant growth and development as well as agricultural characteristics including the final yield. The aim of this review is to summarise recent results of the breeding of barley (Hordeum vulgare) and wheat (Triticum aestivum; T. durum) for improved resistance to drought stress. First, drought-associated terms and definitions are outlined and plant strategies to cope with drought are presented. A brief overview of plant physiological mechanisms involved in water uptake and release is provided. Photosynthesis-related parameters (CO<sub>2</sub> availability and associated features such as ribulose-1,5-bisphosphate carboxylase/oxygenase activity, <sup>13</sup>C discrimination activity, water use efficiency) are discussed due to the crucial role of plant leaf stomata in both photosynthesis and water management. The second part describes the present state of research on drought resistance-associated traits in barley and wheat. Different strategies of plant water management aimed at maximising the final yield under various types of drought stress are discussed. Possibilities of the detection, identification and characterization of quantitative trait loci (QTLs) in barley and wheat germplasm are discussed and the future approaches to breeding for enhanced drought resistance as a complex physiological and agronomical trait are outlined.


2020 ◽  
Vol 6 (8) ◽  
Author(s):  
Irene Picazo ◽  
Oier Etxebeste ◽  
Elena Requena ◽  
Aitor Garzia ◽  
Eduardo Antonio Espeso

Fungi have developed the ability to overcome extreme growth conditions and thrive in hostile environments. The model fungus Aspergillus nidulans tolerates, for example, ambient alkalinity up to pH 10 or molar concentrations of multiple cations. The ability to grow under alkaline pH or saline stress depends on the effective function of at least three regulatory pathways mediated by the zinc-finger transcription factor PacC, which mediates the ambient pH regulatory pathway, the calcineurin-dependent CrzA and the cation homeostasis responsive factor SltA. Using RNA sequencing, we determined the effect of external pH alkalinization or sodium stress on gene expression. The data show that each condition triggers transcriptional responses with a low degree of overlap. By sequencing the transcriptomes of the null mutant, the role of SltA in the above-mentioned homeostasis mechanisms was also studied. The results show that the transcriptional role of SltA is wider than initially expected and implies, for example, the positive control of the PacC-dependent ambient pH regulatory pathway. Overall, our data strongly suggest that the stress response pathways in fungi include some common but mostly exclusive constituents, and that there is a hierarchical relationship among the main regulators of stress response, with SltA controlling pacC expression, at least in A. nidulans.


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