scholarly journals Protein-Protein Interactions and Transcriptional Antagonism between the Subfamily of NGFI-B/Nur77 Orphan Nuclear Receptors and Glucocorticoid Receptor

2005 ◽  
Vol 19 (4) ◽  
pp. 885-897 ◽  
Author(s):  
Christine Martens ◽  
Steve Bilodeau ◽  
Mario Maira ◽  
Yves Gauthier ◽  
Jacques Drouin
Keyword(s):  
Gene Expression ◽  
Dna Binding ◽  
Glucocorticoid Receptor ◽  
Nuclear Receptors ◽  
Protein Interactions ◽  
Orphan Nuclear Receptor ◽  
Orphan Nuclear Receptors ◽  
Related Factors ◽  
Pomc Gene

Abstract Glucocorticoids (Gc) act through the glucocorticoid receptor (GR) to enhance or repress transcription of glucocorticoid-responsive genes depending on the promoter and cellular context. Repression of proopiomelanocortin (POMC) gene expression by Gc was proposed to use different mechanisms. We described the POMC promoter Nur response element (NurRE) as a target for Gc repression. NGFI-B (Nur77), an orphan nuclear receptor, and two related factors, Nurr1 and NOR1, bind the NurRE as homo- or heterodimers to enhance POMC gene expression in response to CRH. Gc antagonize CRH-stimulated as well as NGFI-B-dependent transcription. We now show that GR antagonizes NurRE-dependent transcription induced by all members of the Nur77 subfamily and that these nuclear receptors can all interact directly with GR. Transcriptional antagonism as well as direct protein-protein interaction between NGFI-B and GR take place primarily via their respective DNA binding domains, although DNA binding itself and the GR homodimerization interface are not involved. In vivo, GR and Nur factors can be coimmunoprecipitated whereas GR is recruited to the POMC promoter upon glucocorticoid action. Thus, our data suggest a mechanism for transrepression between two nuclear receptors, GR and NGFI-B, that is unique, although quite similar to that proposed for transrepression between GR and activator protein 1 (AP-1) or nuclear factor-κB (NFκB).

scholarly journals c-Jun Homodimers Can Function as a Context-Specific Coactivator

2007 ◽  
Vol 27 (8) ◽  
pp. 2919-2933 ◽  
Author(s):  
Benoit Grondin ◽  
Martin Lefrancois ◽  
Mathieu Tremblay ◽  
Marianne Saint-Denis ◽  
André Haman ◽  
...  
Keyword(s):  
Gene Expression ◽  
Transcription Factors ◽  
Dna Binding ◽  
Rna Polymerase Ii ◽  
Protein Interactions ◽  
Expression Profiles ◽  
Basic Domain ◽  
Interaction Mode

ABSTRACT Transcription factors can function as DNA-binding-specific activators or as coactivators. c-Jun drives gene expression via binding to AP-1 sequences or as a cofactor for PU.1 in macrophages. c-Jun heterodimers bind AP-1 sequences with higher affinity than homodimers, but how c-Jun works as a coactivator is unknown. Here, we provide in vitro and in vivo evidence that c-Jun homodimers are recruited to the interleukin-1β (IL-1β) promoter in the absence of direct DNA binding via protein-protein interactions with DNA-anchored PU.1 and CCAAT/enhancer-binding protein β (C/EBPβ). Unexpectedly, the interaction interface with PU.1 and C/EBPβ involves four of the residues within the basic domain of c-Jun that contact DNA, indicating that the capacities of c-Jun to function as a coactivator or as a DNA-bound transcription factor are mutually exclusive. Our observations indicate that the IL-1β locus is occupied by PU.1 and C/EBPβ and poised for expression and that c-Jun enhances transcription by facilitating a rate-limiting step, the assembly of the RNA polymerase II preinitiation complex, with minimal effect on the local chromatin status. We propose that the basic domain of other transcription factors may also be redirected from a DNA interaction mode to a protein-protein interaction mode and that this switch represents a novel mechanism regulating gene expression profiles.

scholarly journals Regulation of Macrophage Inflammatory Gene Expression by the Orphan Nuclear Receptor Nur77

2006 ◽  
Vol 20 (4) ◽  
pp. 786-794 ◽  
Author(s):  
Liming Pei ◽  
Antonio Castrillo ◽  
Peter Tontonoz
Keyword(s):  
Gene Expression ◽  
Nuclear Receptors ◽  
Transcriptional Activation ◽  
Liver X Receptor ◽  
Nuclear Hormone Receptor ◽  
Orphan Nuclear Receptor ◽  
Orphan Nuclear Receptors ◽  
Inflammatory Gene Expression ◽  
Inflammatory Gene

Abstract Members of the nuclear hormone receptor superfamily have emerged as important regulators of macrophage gene expression in inflammation and disease. Previous studies have shown that the lipid-activated receptors peroxisomal proliferator-activated receptor and liver X receptor inhibit nuclear factor-κB (NF-κB) signaling and inflammatory gene expression. We recently identified the NR4A subfamily of orphan nuclear receptors (Nur77/NR4A1, Nurr1/NR4A2, and NOR1/NR4A3) as lipopolysaccharide- and NF-κB-responsive genes in macrophages. However, the role of these transcription factors in macrophage gene expression is unknown. We demonstrate here that, in contrast to peroxisomal proliferator-activated receptor and liver X receptor, the role of NR4A receptors in macrophages is proinflammatory. Retroviral expression of Nur77 in macrophages leads to the transcriptional activation of multiple genes involved in inflammation, apoptosis, and cell cycle control. One particularly interesting Nur77-responsive gene is the inducible kinase IKKi/IKKε, an important component of the NF-κB signaling pathway. The IKKi promoter contains a functional NR4A binding site and is activated by all three NR4A receptors in transient transfection assays. Consistent with the activation of IKKi, expression of Nur77 in macrophages potentiates the induction of inflammatory gene expression in response to lipopolysaccharide. These results identify a new role for NR4A orphan nuclear receptors in the control of macrophage gene expression during inflammation.

scholarly journals Compendium of Methods to Uncover RNA-Protein Interactions In Vivo

2021 ◽  
Vol 4 (1) ◽  
pp. 22
Author(s):  
Mrinmoyee Majumder ◽  
Viswanathan Palanisamy
Keyword(s):  
Gene Expression ◽  
Protein Interactions ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Expression Patterns ◽  
Control Of Gene Expression ◽  
Regulatory Pathways ◽  
Advantages And Disadvantages ◽  
Protein Nucleic Acid

Control of gene expression is critical in shaping the pro-and eukaryotic organisms’ genotype and phenotype. The gene expression regulatory pathways solely rely on protein–protein and protein–nucleic acid interactions, which determine the fate of the nucleic acids. RNA–protein interactions play a significant role in co- and post-transcriptional regulation to control gene expression. RNA-binding proteins (RBPs) are a diverse group of macromolecules that bind to RNA and play an essential role in RNA biology by regulating pre-mRNA processing, maturation, nuclear transport, stability, and translation. Hence, the studies aimed at investigating RNA–protein interactions are essential to advance our knowledge in gene expression patterns associated with health and disease. Here we discuss the long-established and current technologies that are widely used to study RNA–protein interactions in vivo. We also present the advantages and disadvantages of each method discussed in the review.

scholarly journals DNA binding-dependent glucocorticoid receptor activity promotes adipogenesis via Krüppel-like factor 15 gene expression

2010 ◽  
Vol 91 (2) ◽  
pp. 203-215 ◽  
Author(s):  
Maki Asada ◽  
Alexander Rauch ◽  
Hirohito Shimizu ◽  
Hiromi Maruyama ◽  
Shigeru Miyaki ◽  
...  
Keyword(s):  
Gene Expression ◽  
Dna Binding ◽  
Glucocorticoid Receptor ◽  
Receptor Activity

Identification of a killer cell-specific regulatory element of the mouse perforin gene: an Ets-binding site-homologous motif that interacts with Ets-related proteins

1993 ◽  
Vol 13 (11) ◽  
pp. 6690-6701
Author(s):  
H Koizumi ◽  
M F Horta ◽  
B S Youn ◽  
K C Fu ◽  
B S Kwon ◽  
...  
Keyword(s):  
Gene Expression ◽  
Dna Binding ◽  
Binding Site ◽  
Protein Interactions ◽  
Regulatory Element ◽  
Killer Cell ◽  
Mobility Shift ◽  
Specific Expression ◽  
Native Molecular Mass ◽  
Mobility Shift Assay

The gene encoding the cytolytic protein perforin is selectively expressed by activated killer lymphocytes. To understand the mechanisms underlying the cell-type-specific expression of this gene, we have characterized the regulatory functions and the DNA-protein interactions of the 5'-flanking region of the mouse perforin gene (Pfp). A region extending from residues +62 through -141, which possesses the essential promoter activity, and regions further upstream, which are able to either enhance or suppress gene expression, were identified. The region between residues -411 and -566 was chosen for further characterization, since it contains an enhancer-like activity. We have identified a 32-mer sequence (residues -491 to -522) which appeared to be capable of enhancing gene expression in a killer cell-specific manner. Within this segment, a 9-mer motif (5'-ACAGGAAGT-3', residues -505 to -497; designated NF-P motif), which is highly homologous to the Ets proto-oncoprotein-binding site, was found to interact with two proteins, NF-P1 and NF-P2. NF-P2 appears to be induced by reagents known to up-regulate the perforin message level and is present exclusively in killer cells. Electrophoretic mobility shift assay and UV cross-linking experiments revealed that NF-P1 and NF-P2 may possess common DNA-binding subunits. However, the larger native molecular mass of NF-P1 suggests that NF-P1 contains an additional non-DNA-binding subunit(s). In view of the homology between the NF-P motif and other Ets proto-oncoprotein-binding sites, it is postulated that NF-P1 and NF-P2 belong to the Ets protein family. Results obtained from the binding competition assay, nevertheless, suggest that NF-P1 and NF-P2 are related to but distinct from Ets proteins, e.g., Ets-1, Ets-2, and NF-AT/Elf-1, known to be expressed in T cells.

Identification of DNA elements cooperatively activating proopiomelanocortin gene expression in the pituitary glands of transgenic mice

1992 ◽  
Vol 12 (9) ◽  
pp. 3978-3990
Author(s):  
B Liu ◽  
G D Hammer ◽  
M Rubinstein ◽  
M Mortrud ◽  
M J Low
Keyword(s):  
Gene Expression ◽  
Transgenic Mice ◽  
Reporter Gene ◽  
Transgene Expression ◽  
Intermediate Lobe ◽  
Mobility Shift ◽  
Specific Expression ◽  
Dna Elements ◽  
Pomc Gene

The proopiomelanocortin (POMC) gene is highly expressed in adult mouse pituitary anterior lobe corticotrophs and intermediate lobe melanotrophs. To identify the DNA elements important for this tissue-specific expression, we analyzed a series of POMC reporter genes in transgenic mice. A DNA fragment containing rat POMC 5'-flanking sequences from -323 to -34 recapitulated both basal pituitary cell-specific and hormonally stimulated expression in adult mice when fused to a heterologous thymidine kinase promoter. Developmental onset of the reporter gene expression lagged by 1 day but otherwise closely paralleled the normal ontogeny of murine POMC gene expression, including corticotroph activation at embryonic day 14.5 (E14.5) followed by melanotroph activation at E15.5 to E16.5. AtT20 corticotroph nuclear protein extracts interacted with three specific regions of the functional POMC promoter in DNase I protection assays. The positions of these protected sites were -107 to -160 (site 1), -182 to -218 (site 2), and -249 to -281 (site 3). Individual deletions of these footprinted sites did not alter transgene expression; however, the simultaneous deletion of sites 2 and 3 prevented transgene expression in both corticotrophs and melanotrophs. Electrophoretic mobility shift and Southwestern (DNA-protein) assays demonstrated that multiple AtT20 nuclear proteins bound to these footprinted sites. We conclude that the sequences between -323 and -34 of the rat POMC gene promoter are both necessary and sufficient for correct spatial, temporal, and hormonally regulated expression in the pituitary gland. Our data suggest that the three footprinted sites within the promoter are functionally interchangeable and act in combination with promoter elements between -114 and -34. The inability of any reporter gene construction to dissociate basal and hormonally stimulated expression suggests that these DNA elements are involved in both of these two characteristics of POMC gene expression in vivo.

scholarly journals Fused protein domains inhibit DNA binding by LexA.

1992 ◽  
Vol 12 (7) ◽  
pp. 3006-3014 ◽  
Author(s):  
E A Golemis ◽  
R Brent
Keyword(s):  
Dna Binding ◽  
Protein Interactions ◽  
In Vitro Assays ◽  
Dimerization Domain ◽  
Activation Domains ◽  
Dna Binding Domains ◽  
Binding Domains ◽  
Operator Binding

Many studies of transcription activation employ fusions of activation domains to DNA binding domains derived from the bacterial repressor LexA and the yeast activator GAL4. Such studies often implicitly assume that DNA binding by the chimeric proteins is equivalent to that of the protein donating the DNA binding moiety. To directly investigate this issue, we compared operator binding by a series of LexA-derivative proteins to operator binding by native LexA, by using both in vivo and in vitro assays. We show that operator binding by many proteins such as LexA-Myc, LexA-Fos, and LexA-Bicoid is severely impaired, while binding of other LexA-derivative proteins, such as those that carry bacterially encoded acidic sequences ("acid blobs"), is not. Our results also show that DNA binding by LexA derivatives that contain the LexA carboxy-terminal dimerization domain (amino acids 88 to 202) is considerably stronger than binding by fusions that lack it and that heterologous dimerization motifs cannot substitute for the LexA88-202 function. These results suggest the need to reevaluate some previous studies of activation that employed LexA derivatives and modifications to recent experimental approaches that use LexA and GAL4 derivatives to detect and study protein-protein interactions.

scholarly journals Interaction of the v-Rel oncoprotein with NF-kappaB and IkappaB proteins: heterodimers of a transformation-defective v-Rel mutant and NF-2 are functional in vitro and in vivo.

1996 ◽  
Vol 16 (3) ◽  
pp. 1169-1178 ◽  
Author(s):  
D W White ◽  
G A Pitoc ◽  
T D Gilmore
Keyword(s):  
Dna Binding ◽  
Protein Interactions ◽  
Cellular Protein ◽  
Lymphoid Cells ◽  
Spleen Cells ◽  
Nf Kappa B ◽  
I Kappa B Alpha ◽  
Chicken Spleen

The v-Rel oncoprotein of the avian Rev-T retrovirus is a member of the Rel/NF-kappa B family of transcription factors. The mechanism by which v-Rel malignantly transforms chicken spleen cells is not precisely known. To gain a better understanding of functions needed for transformation by v-Rel, we have now characterized the activities of mutant v-Rel proteins that are defective for specific protein-protein interactions. Mutant v-delta NLS, which has a deletion of the primary v-Rel nuclear localizing sequence, does not interact efficiently with I kappa B-alpha but still transforms chicken spleen cells approximately as well as wild-type v-Rel, indicating that interaction with I kappa B-alpha is not essential for the v-Rel transforming function. A second v-Rel mutant, v-SPW, has been shown to be defective for the formation of homodimers, DNA binding, and transformation. However, we now find that v-SPW can form functional DNA-binding heterodimers in vitro and in vivo with the cellular protein NF-kappa B p-52. Most strikingly, coexpression of v-SPW and p52 from a retroviral vector can induce the malignant transformation of chicken spleen cells, whereas expression of either protein alone cannot. Our results are most consistent with a model wherein Rel homodimers or heterodimers must bind DNA and alter gene expression in order to transform lymphoid cells.

scholarly journals Glucocorticoid receptor action in metabolic and neuronal function

F1000Research ◽  
2017 ◽  
Vol 6 ◽  
pp. 1208 ◽  
Author(s):  
Michael J. Garabedian ◽  
Charles A. Harris ◽  
Freddy Jeanneteau
Keyword(s):  
Gene Expression ◽  
Glucocorticoid Receptor ◽  
Metabolic Diseases ◽  
Cell Types ◽  
Health And Disease ◽  
And Behavior ◽  
External Signals ◽  
The Brain

Glucocorticoids via the glucocorticoid receptor (GR) have effects on a variety of cell types, eliciting important physiological responses via changes in gene expression and signaling. Although decades of research have illuminated the mechanism of how this important steroid receptor controls gene expression using in vitro and cell culture–based approaches, how GR responds to changes in external signals in vivo under normal and pathological conditions remains elusive. The goal of this review is to highlight recent work on GR action in fat cells and liver to affect metabolism in vivo and the role GR ligands and receptor phosphorylation play in calibrating signaling outputs by GR in the brain in health and disease. We also suggest that both the brain and fat tissue communicate to affect physiology and behavior and that understanding this “brain-fat axis” will enable a more complete understanding of metabolic diseases and inform new ways to target them.

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