Emerging functions of multi-protein complex Mediator with special emphasis on plants

Malik, Naveen; Agarwal, Pinky; Tyagi, Akhilesh K.

doi:10.1080/10409238.2017.1325830

Cited by 30 publications

(28 citation statements)

References 281 publications

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“…Depending on the species, the number of Mediator subunits may vary, and there are approximately 34 subunits reported in plant Mediator [ 11 ]. A number of Mediator subunits has already been revealed to have critical functions in various plant developmental processes, hormone signaling, plant defense, and abiotic stress tolerance [ 1 , 3 , 12 , 13 ]. The head module primarily associates with Pol II to affect transcription whereas the tail module is believed to play a highly significant role as it interacts with gene-specific TFs.…”

Section: Introductionmentioning

confidence: 99%

Mediator Complex: A Pivotal Regulator of ABA Signaling Pathway and Abiotic Stress Response in Plants

Chong

Guo

Zhu

2020

IJMS

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As an evolutionarily conserved multi-protein complex, the Mediator complex modulates the association between transcription factors and RNA polymerase II to precisely regulate gene transcription. Although numerous studies have shown the diverse functions of Mediator complex in plant development, flowering, hormone signaling, and biotic stress response, its roles in the Abscisic acid (ABA) signaling pathway and abiotic stress response remain largely unclear. It has been recognized that the phytohormone, ABA, plays a predominant role in regulating plant adaption to various abiotic stresses as ABA can trigger extensive changes in the transcriptome to help the plants respond to environmental stimuli. Over the past decade, the Mediator complex has been revealed to play key roles in not only regulating the ABA signaling transduction but also in the abiotic stress responses. In this review, we will summarize current knowledge of the Mediator complex in regulating the plants’ response to ABA as well as to the abiotic stresses of cold, drought and high salinity. We will particularly emphasize the involvement of multi-functional subunits of MED25, MED18, MED16, and CDK8 in response to ABA and environmental perturbation. Additionally, we will discuss potential research directions available for further deciphering the role of Mediator complex in regulating ABA and other abiotic stress responses.

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Section: Introductionmentioning

confidence: 99%

Mediator Complex: A Pivotal Regulator of ABA Signaling Pathway and Abiotic Stress Response in Plants

Chong

Guo

Zhu

2020

IJMS

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“…Various biochemical techniques and biophysical structural analyses have revealed 21 conserved subunits and six additional plant-specific subunits in Arabidopsis thaliana, whose positions in the complex are unassigned [8]. The physiological and cellular functions of several plant MED subunits have been deciphered by different forward/reverse genetic approaches and specific phenotypes of viable individual subunit mutants [9]. In Arabidopsis, for instance, the MED25 subunit is involved in the regulation of diverse physiological processes such as flowering, organ development, hormone signaling pathways and stress response [10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Mapping the Gene Expression Spectrum of Mediator Subunits in Response to Viroid Infection in Plants

Nath

Shrestha

Awasthi

et al. 2020

IJMS

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The mediator (MED) represents a large, conserved, multi-subunit protein complex that regulates gene expression through interactions with RNA polymerase II and enhancer-bound transcription factors. Expanding research accomplishments suggest the predominant role of plant MED subunits in the regulation of various physiological and developmental processes, including the biotic stress response against bacterial and fungal pathogens. However, the involvement of MED subunits in virus/viroid pathogenesis remains elusive. In this study, we investigated for the first time the gene expression modulation of selected MED subunits in response to five viroid species (Apple fruit crinkle viroid (AFCVd), Citrus bark cracking viroid (CBCVd), Hop latent viroid (HLVd), Hop stunt viroid (HSVd), and Potato spindle tuber viroid (PSTVd)) in two model plant species (Nicotiana tabacum and N. benthamiana) and a commercially important hop (Humulus lupulus) cultivar. Our results showed a differential expression pattern of MED subunits in response to a viroid infection. The individual plant MED subunits displayed a differential and tailored expression pattern in response to different viroid species, suggesting that the MED expression is viroid- and plant species-dependent. The explicit evidence obtained from our results warrants further investigation into the association of the MED subunit with symptom development. Together, we provide a comprehensive portrait of MED subunit expression in response to viroid infection and a plausible involvement of MED subunits in fine-tuning transcriptional reprogramming in response to viroid infection, suggesting them as a potential candidate for rewiring the defense response network in plants against pathogens.

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“…Mediator is an evolutionarily-conserved complex composed of 25 to 30 distinct proteins distributed in four modules: head, middle, and tail forming the core MED, and a separable regulatory Cdk8 kinase module (CKM) (1). Despite a general role of the Mediator complex in regulating transcription, some MED subunits display striking functional specificities, as exemplified by their differential requirements for cell viability (4,5), their involvement in specific human diseases (6,7), or their roles in given developmental processes (8)(9)(10). It has been proposed that MED subunit specificity comes from their ability to contact specific transcription factors and mediate their regulatory activity (11,12).…”

Section: Introductionmentioning

confidence: 99%

Mediator complex subunit Med19 binds directly GATA DNA-binding zinc finger and functions with Med1 in GATA-driven gene regulationin vivo

Immarigeon

Bernat-Fabre

Guillou

et al. 2020

Preprint

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The evolutionarily-conserved multiprotein Mediator complex (MED) serves as an interface between DNA-bound transcription factors (TFs) and the RNA Polymerase II machinery. It has been proposed that each TF interacts with a dedicated MED subunit to induce specific transcriptional responses. However, binary MED subunit -TF partnerships are probably oversimplified models. Using Drosophila TFs of the GATA family -Pannier (Pnr) and Serpent (Srp) -as a model, we have previously established GATA cofactor evolutionarily-conserved function for the Med1 Mediator subunit. Here, we show that another subunit, Med19, is required for GATA-dependent gene expression and interacts physically with Pnr and Srp in cellulo, in vivo and in vitro through their conserved Czinc finger (ZF), indicating general GATA coactivator functions. Interestingly, Med19 is critical for the regulation of all tested GATA target genes which is not the case for Med1, suggesting differential use of MED subunits by GATAs depending on the target gene. Lastly, despite their presumed distant position within the MED middle module, both subunits interact physically. In conclusion, our data shed new light first on the MED complex, engaging several subunits to mediate TFdriven transcriptional responses and second, on GATA TFs, showing that ZF DNA-binding domain also serves for transactivation.

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Emerging functions of multi-protein complex Mediator with special emphasis on plants

Cited by 30 publications

References 281 publications

Mediator Complex: A Pivotal Regulator of ABA Signaling Pathway and Abiotic Stress Response in Plants

Mediator Complex: A Pivotal Regulator of ABA Signaling Pathway and Abiotic Stress Response in Plants

Mapping the Gene Expression Spectrum of Mediator Subunits in Response to Viroid Infection in Plants

Mediator complex subunit Med19 binds directly GATA DNA-binding zinc finger and functions with Med1 in GATA-driven gene regulationin vivo

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