Multiple steps in the regulation of transcription-factor level and activity

Calkhoven, Cornelis F.; Ab, Geert

doi:10.1042/bj3170329

Cited by 150 publications

(129 citation statements)

References 273 publications

(313 reference statements)

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“…These effects, in turn, could be mediated by a number of different mechanisms, including (de)phosphorylation, altered protein turnover, changes in subcellular localization, and/or sequestration. The importance of these processes in regulating the activity of transcription factors in other systems has been abundantly documented (Calkhoven and Ab, 1996).…”

Section: Discussionmentioning

confidence: 99%

The Arabidopsis NPR1/NIM1 Protein Enhances the DNA Binding Activity of a Subgroup of the TGA Family of bZIP Transcription Factors

et al. 2000

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The Arabidopsis NPR1 gene is essential in activating systemic, inducible plant defense responses. To gain a better understanding of NPR1 function, we conducted a yeast two-hybrid screening procedure and identified a differential interaction between NPR1 and all known members of the Arabidopsis TGA family of basic leucine zipper transcription factors. In the electrophoretic mobility shift assay, NPR1 substantially increased the binding of TGA2 to its cognate promoter element ( as-1 ) as well as to a positive salicylic acid-inducible element ( LS7 ) and a negative element ( LS5 ) in the promoter of the pathogenesis-related PR-1 gene. Proteins encoded by npr1 mutants interacted poorly with TGA2 and did not substantially increase TGA2 binding to the as-1 , LS5 , or LS7 elements, thus establishing a link between the loss of disease resistance and the loss of TGA2 interaction and NPR1-enhanced DNA binding. Coupled with observations that the DNA binding activity of TGA factors is deregulated in npr1 plants, the results suggest that NPR1-mediated DNA binding of TGA2 is critical for activation of defense genes.

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Section: Discussionmentioning

confidence: 99%

The Arabidopsis NPR1/NIM1 Protein Enhances the DNA Binding Activity of a Subgroup of the TGA Family of bZIP Transcription Factors

et al. 2000

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“…However, some mRNAs encoding transcription factors are subjected to regulated splicing. This can produce mRNAs encoding different transcription factors with distinct functions (51)(52)(53)(54)(55). Natural and artificially incomplete transcription factors (lacking the activation domain) are able to interact with complete factors and act as negative dominants (44 -47, 56).…”

Section: Discussionmentioning

confidence: 99%

The Product of the Rice myb7 Unspliced mRNA Dimerizes with the Maize Leucine Zipper Opaque2 and Stimulates Its Activity in a Transient Expression Assay

Locatelli

Bracale²,

Magaraggia³

et al. 2000

Journal of Biological Chemistry

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myb7 mRNA is present in rice in spliced and unspliced forms, splicing being enhanced by anoxia. The protein (Mybleu) encoded by the unspliced mRNA is composed of an incomplete Myb domain followed by a leucine zipper; however, it lacks canonical sequences for DNA binding, transcriptional activation, and nuclear localization. We show here that in transiently transformed tobacco protoplasts, Mybleu is able to enhance the transcriptional activity of the maize leucine zipper Opaque2 on its target b32 promoter. The Mybleu transactivation effect is strictly dependent on the presence of Opaque2 and is driven by Mybleu-Opaque2 heterodimers. Mybleu is located in the nucleus, both in rice and in transformed tobacco protoplasts. In rice, the protein is expressed in regions corresponding to undifferentiated cells of roots and coleoptiles. Therefore, myb7 mRNA encodes, depending on its splicing, two transcription factors belonging to separate classes. One of them, Mybleu, has novel structural characteristics, suggesting the existence of new mechanisms acting in the activation of transcription.Mybs are a family of transcription factors widely represented in viruses, insects, mammals, and plants. The common feature of Myb factors is the presence of a conserved domain consisting of imperfect repeats of 50 -53 amino acids, called "tryptophan clusters" because of the highly conserved tryptophan residues involved in stabilizing the structure of the DNA binding domain (1). In plants, myb genes are present as large families (6 -100 members) involved in the control of a wide range of biochemical pathways (2-6), including responses to biotic and abiotic stresses (7-13).Screening a cDNA library from anaerobically grown rice coleoptiles, we isolated myb7, a cDNA derived from a Mybencoding unspliced mRNA (8). Some features of myb7 sequence indicate that it may be post-transcriptionally regulated; in particular, two unspliced introns are present in positions that are conserved with respect to other plant myb genes. Both spliced and unspliced myb7 mRNAs are present in vivo (7).In aerobically grown rice roots, we observed a higher proportion of unspliced myb7 RNA, with respect to the spliced form. The spliced form is instead predominant in rice roots during anoxia, a stress situation that generally inhibits splicing (14). These data suggest that post-transcriptional regulation controls the ratio between myb7 unspliced and spliced forms (7). This hypothesis is supported by the observation that the 5Ј region of the first intron can direct the synthesis of an in-frame leucine zipper, a functional domain present in several transcription factors (15-18).The putative polypeptide encoded by the unspliced myb7 mRNA consists of an incomplete Myb domain followed by the leucine zipper: we therefore named it Mybleu. Mybleu does not have the characteristics of a functional transcription factor. Indeed, it should be unable to bind DNA because of the presence of an incomplete Myb repeat. Moreover, neither a putative transcriptional activator region nor a c...

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“…On DNA, the unbound receptors are associated to co-repressors and silence active promoters. When ligand binds the receptor, the co-repressor dissociates, allowing interaction with other transcription factors and co-activators, and leading to gene activation [32,86,100,253].…”

Section: The Steps Of Adipose Conversionmentioning

confidence: 99%

The adipose conversion process: regulation by extracellular and intracellular factors

Boone

Mourot

Gregoire³

et al. 2000

Reprod. Nutr. Dev.

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-White adipose tissue regulates lipid metabolism and acts as a secretory organ. Because of its importance for human health and animal production, many studies have attempted to better understand its development at the cellular and molecular levels by culturing preadipose cells in vitro. This synthesis article describes our current knowledge, acquired by this approach, concerning the regulation of the different steps of the adipocyte differentiation program by extracellular (hormones, cytokines, growth factors, retinoids and fatty acids) and intracellular agents (second messengers and transcription factors). The discrepant effects that have been observed for some of these factors are also discussed. This information is very important in the perspective of a better control of fat deposits in human and breeding species.preadipocyte / differentiation / hormonal agent / second messenger / transcription factor Résumé -Le processus d'adipoconversion : sa régulation par des facteurs extracellulaires et intracellulaires. Le tissu adipeux blanc régule le métabolisme lipidique et agit comme un organe de sécrétion. Étant donné son importance pour la santé humaine et la production animale, de nombreuses études ont tenté de mieux comprendre son développement aux niveaux cellulaire et moléculaire en utilisant des cultures de préadipocytes. Cet article de synthèse décrit notre connaissance actuelle, issue de cette approche, concernant la régulation des différentes étapes du programme de la diffé-renciation adipocytaire par des facteurs extracellulaires (hormones, cytokines, facteurs de croissance, rétinoïdes et acides gras) et intracellulaires (seconds messagers et facteurs de transcription). Les effets divergents observés pour certains de ces facteurs sont également discutés. Ces informations sont très importantes dans la perspective d'un meilleur contrôle des dépôts adipeux chez l'humain et les espèces d'élevage.préadipocyte / différenciation / hormone / second messager / facteur de transcription Reprod. Nutr. Dev. 40 (2000) 325-358 325

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Multiple steps in the regulation of transcription-factor level and activity

Cited by 150 publications

References 273 publications

The Arabidopsis NPR1/NIM1 Protein Enhances the DNA Binding Activity of a Subgroup of the TGA Family of bZIP Transcription Factors

The Arabidopsis NPR1/NIM1 Protein Enhances the DNA Binding Activity of a Subgroup of the TGA Family of bZIP Transcription Factors

The Product of the Rice myb7 Unspliced mRNA Dimerizes with the Maize Leucine Zipper Opaque2 and Stimulates Its Activity in a Transient Expression Assay

The adipose conversion process: regulation by extracellular and intracellular factors

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