Sequentiality and processivity of nuclear receptor coregulators in regulation of target gene expression

ABSTRACT Mediator is a general coactivator complex connecting transcription activators and RNA polymerase II. Recent work has shown that the nuclear receptor-interacting MED1/TRAP220 subunit of Mediator is required for peroxisome proliferator-activated receptor γ (PPARγ)-stimulated adipogenesis of mouse embryonic fibroblasts (MEFs). However, the molecular mechanisms remain undefined. Here, we show an intracellular PPARγ-Mediator interaction that requires the two LXXLL nuclear receptor recognition motifs on MED1/TRAP220 and, furthermore, we show that the intact LXXLL motifs are essential for optimal PPARγ function in a reconstituted cell-free transcription system. Surprisingly, a conserved N-terminal region of MED1/TRAP220 that lacks the LXXLL motifs but gets incorporated into Mediator fully supports PPARγ-stimulated adipogenesis. Moreover, in undifferentiated MEFs, MED1/TRAP220 is dispensable both for PPARγ-mediated target gene activation and for recruitment of Mediator to a PPAR response element on the aP2 target gene promoter. However, PPARγ shows significantly reduced transcriptional activity in cells deficient for a subunit (MED24/TRAP100) important for the integrity of the Mediator complex, indicating a general Mediator requirement for PPARγ function. These results indicate that there is a conditional requirement for MED1/TRAP220 and that a direct interaction between PPARγ and Mediator through MED1/TRAP220 is not essential either for PPARγ-stimulated adipogenesis or for PPARγ target gene expression in cultured fibroblasts. As Mediator is apparently essential for PPARγ transcriptional activity, our data indicate the presence of alternative mechanisms for Mediator recruitment, possibly through intermediate cofactors or other cofactors that are functionally redundant with MED1/TRAP220.

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Liver X Receptors Interact with Corepressors to Regulate Gene Expression

Molecular Endocrinology ◽

10.1210/me.2002-0399 ◽

2003 ◽

Vol 17 (6) ◽

pp. 1019-1026 ◽

Cited By ~ 99

Author(s):

Xiao Hu ◽

Suzhen Li ◽

Jun Wu ◽

Chunsheng Xia ◽

Deepak S. Lala

Keyword(s):

Gene Expression ◽

Nuclear Receptor ◽

Target Gene ◽

Critical Role ◽

Cholesterol Homeostasis ◽

Liver X Receptors ◽

Regulate Gene Expression ◽

Target Gene Expression ◽

X Receptors ◽

Regulate Gene

Abstract Liver X receptors (LXRs) are members of the nuclear receptor superfamily that regulate gene expression in response to oxysterols and play a critical role in cholesterol homeostasis by regulating genes that are involved in cholesterol transport, catabolism, and triglyceride synthesis. Oxysterols and synthetic agonists bind LXRs and activate transcription by recruiting coactivator proteins. The role of LXRs in regulating target gene expression in the absence of ligand is unknown. Here we show that LXRs interact with corepressors, N-CoR (nuclear receptor corepressor) and SMRT (silent mediator of retinoic acid receptor and thyroid receptor), which are released upon binding agonists. The LXR-corepressor interaction is isoform selective, wherein LXRα has a very strong interaction with corepressors and LXRβ only shows weak interaction. LXRs also exhibit a preference for interacting with N-CoR vs. SMRT. Similar to other nuclear receptors, mutations in the LXR helix 3 and 4 region abolish corepressor interaction. Using a transient transfection assay, we demonstrate that LXR represses transcription that can be further increased by cotransfecting N-CoR into cells. Chromatin immunoprecipitation experiments further indicated that N-CoR is recruited onto endogenous LXR target genes, and addition of LXR agonists releases N-CoR from their promoters. Collectively, these results suggest that corepressors play an important role in regulating LXR target gene expression.

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Tissue- and Nuclear Receptor-Specific Function of the C-Terminal LXXLL Motif of Coactivator NCoA6/AIB3 in Mice

Molecular and Cellular Biology ◽

10.1128/mcb.00451-07 ◽

2007 ◽

Vol 27 (23) ◽

pp. 8073-8086 ◽

Cited By ~ 18

Author(s):

Qingtian Li ◽

Mei-Jin Chu ◽

Jianming Xu

Keyword(s):

Gene Expression ◽

Mammary Gland ◽

Bile Acid ◽

Nuclear Receptor ◽

Target Gene ◽

Acid Synthesis ◽

Estrogen Receptor Α ◽

High Cholesterol Diet ◽

Target Gene Expression ◽

Lxxll Motif

ABSTRACT Although the LXXLL motif of nuclear receptor (NR) coactivators is essential for interaction with NRs, its role has not been assessed in unbiased animal models. The nuclear receptor coactivator 6 (NCoA6; also AIB3, PRIP, ASC-2, TRBP, RAP250, or NRC) is a coactivator containing an N-terminal LXXLL-1 (L1) and a C-terminal L2. L1 interacts with many NRs, while L2 interacts with the liver X receptor α (LXRα) and the estrogen receptor α (ERα). We generated mice in which L2 was mutated into AXXAL (L2m) to disrupt its interaction with LXRα and ERα. NCoA6L2m/L2m mice exhibited normal reproduction, mammary gland morphogenesis, and ERα target gene expression. In contrast, when treated with an LXRα agonist, lipogenesis and the LXRα target gene expression were significantly reduced in NCoA6L2m/L2m mice. The induction of Cyp7A1 expression by a high-cholesterol diet was impaired in NCoA6L2m/L2m mice, which reduced bile acid synthesis in the liver and excretion in the feces and resulted in cholesterol accumulation in the liver and blood. These results demonstrate that L2 plays a tissue- and NR-specific role: it is required for NCoA6 to mediate LXRα-regulated lipogenesis and cholesterol/bile acid homeostasis in the liver but not required for ERα function in the mammary gland.

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An extract from date palm fruit (Phoenix dactylifera) acts as a co-agonist ligand for the nuclear receptor FXR and differentially modulates FXR target-gene expression in vitro

PLoS ONE ◽

10.1371/journal.pone.0190210 ◽

2018 ◽

Vol 13 (1) ◽

pp. e0190210 ◽

Cited By ~ 8

Author(s):

Emilia Alfaro-Viquez ◽

Brent F. Roling ◽

Christian G. Krueger ◽

Charlene J. Rainey ◽

Jess D. Reed ◽

...

Keyword(s):

Gene Expression ◽

Nuclear Receptor ◽

Target Gene ◽

Date Palm ◽

Phoenix Dactylifera ◽

Palm Fruit ◽

Target Gene Expression

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2049-P: The Chd4 Helicase of the Nucleosome Remodeling and Deacetylase Complex Modulates Pdx1 Target Gene Expression In Vitro

Diabetes ◽

10.2337/db20-2049-p ◽

2020 ◽

Vol 69 (Supplement 1) ◽

pp. 2049-P

Author(s):

REBECCA K. DAVIDSON ◽

NOLAN CASEY ◽

JASON SPAETH

Keyword(s):

Gene Expression ◽

Target Gene ◽

Nucleosome Remodeling ◽

Target Gene Expression

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On the way toward regulatable expression systems in acetic acid bacteria: target gene expression and use cases

Applied Microbiology and Biotechnology ◽

10.1007/s00253-021-11269-z ◽

2021 ◽

Author(s):

Philipp Moritz Fricke ◽

Angelika Klemm ◽

Michael Bott ◽

Tino Polen

Keyword(s):

Gene Expression ◽

Acetic Acid ◽

Literature Search ◽

Target Gene ◽

Target Genes ◽

Recombinant Dna ◽

Acetic Acid Bacteria ◽

Homoserine Lactone ◽

Expression Systems ◽

Target Gene Expression

Abstract Acetic acid bacteria (AAB) are valuable biocatalysts for which there is growing interest in understanding their basics including physiology and biochemistry. This is accompanied by growing demands for metabolic engineering of AAB to take advantage of their properties and to improve their biomanufacturing efficiencies. Controlled expression of target genes is key to fundamental and applied microbiological research. In order to get an overview of expression systems and their applications in AAB, we carried out a comprehensive literature search using the Web of Science Core Collection database. The Acetobacteraceae family currently comprises 49 genera. We found overall 6097 publications related to one or more AAB genera since 1973, when the first successful recombinant DNA experiments in Escherichia coli have been published. The use of plasmids in AAB began in 1985 and till today was reported for only nine out of the 49 AAB genera currently described. We found at least five major expression plasmid lineages and a multitude of further expression plasmids, almost all enabling only constitutive target gene expression. Only recently, two regulatable expression systems became available for AAB, an N-acyl homoserine lactone (AHL)-inducible system for Komagataeibacter rhaeticus and an l-arabinose-inducible system for Gluconobacter oxydans. Thus, after 35 years of constitutive target gene expression in AAB, we now have the first regulatable expression systems for AAB in hand and further regulatable expression systems for AAB can be expected. Key points • Literature search revealed developments and usage of expression systems in AAB. • Only recently 2 regulatable plasmid systems became available for only 2 AAB genera. • Further regulatable expression systems for AAB are in sight.

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