Structure-Function Analysis of the Rev-erbA and RVR Ligand-Binding Domains Reveals a Large Hydrophobic Surface That Mediates Corepressor Binding and a Ligand Cavity Occupied by Side Chains

Renaud, Jean‐Paul; Harris, Jonathan M.; Downes, Michael; Burke, Les J.; Muscat, George E.O.

doi:10.1210/mend.14.5.0444

Cited by 49 publications

(33 citation statements)

References 55 publications

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“…Recent structure-function analysis and three-dimensional modeling of Rev-Erb␣ indicated that the structure of the putative ligand cavity is occupied by side chains, suggesting that this receptor may not have any endogenous ligands (41). Therefore, the regulation of Rev-Erb␣ expression constitutes a crucial level of control of receptor activity.…”

Section: Discussionmentioning

confidence: 99%

The Orphan Nuclear Receptor Rev-Erbα Is a Peroxisome Proliferator-activated Receptor (PPAR) γ Target Gene and Promotes PPARγ-induced Adipocyte Differentiation

Fontaine

Dubois

Duguay

et al. 2003

Journal of Biological Chemistry

219

179

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Rev-Erb␣ (NR1D1) is an orphan nuclear receptor encoded on the opposite strand of the thyroid receptor ␣ gene. Rev-Erb␣ mRNA is induced during adipocyte differentiation of 3T3-L1 cells, and its expression is abundant in rat adipose tissue. Peroxisome proliferator-activated receptor ␥ (PPAR␥) (NR1C3) is a nuclear receptor controlling adipocyte differentiation and insulin sensitivity. Here we show that Rev-Erb␣ expression is induced by PPAR␥ activation with rosiglitazone in rat epididymal and perirenal adipose tissues in vivo as well as in 3T3-L1 adipocytes in vitro. Adipocyte differentiation is a complex biological process, which is reflected at the molecular level by the transcriptional activation of a number of adipocyte-specific genes and by the acquisition of the ability to accumulate cytoplasmic lipid droplets (1-3). The nuclear receptor peroxisome proliferator-activated receptor ␥ (PPAR␥, 1 NR1C3) (4, 5) and members of the CCAAT enhancer-binding protein (C/EBP) family (6 -12) play key roles in this adipogenic process. In addition, the adipocyte differentiation and determination factor-1 (SREBP-1/ADD1) appears to promote adipocyte differentiation by activating the expression of PPAR␥ and increasing the synthesis of endogenous PPAR␥ ligands (13-15). Members of the PPAR family bind as heterodimers with the retinoid X receptors (RXR) to specific response elements termed peroxisome proliferator response elements (PPRE) (for review see Ref. 16). These PPREs usually consist of a direct repeat of the PuGGTCA motif spaced by one nucleotide (DR1). The transcriptional activity of the PPARs is activated by a number of different fatty acid metabolites, most notably products of the cycloxygenase and lipoxygenase pathways. In addition, a large number of synthetic compounds are known to be potent and subtype specific PPAR ligands. For example, thiazolidinedione compounds used as insulin sensitizers in the treatment of type II diabetes are high affinity PPAR␥ ligands (17).Rev-Erb␣ (NR1D1) is another nuclear receptor, the expression of which is induced during adipocyte differentiation (18). Rev-Erb␣ is highly expressed in adipose tissue but also in skeletal muscle, liver and brain (18 -21). Since no ligand has been identified so far, Rev-Erb␣ is considered as an orphan member of the nuclear receptor superfamily. Rev-Erb␣ has been shown to act as a negative regulator of transcription (22) binding either as monomer on nuclear receptor half-site motifs flanked 5Ј by an A/T rich sequence (A/T PuGGTCA), or as a homodimer to a direct repeat of the PuGGTCA motif spaced by two nucleotides (DR2).We have previously shown that PPAR␣ activates the expression of Rev-Erb␣ through an atypical PPRE, a DR-2 element, in the Rev-Erb␣ promoter (23). Transcriptional activation by PPAR␥ through a DR-2 element has so far not been reported. However, since Rev-Erb␣ is induced during the course of adipocyte differentiation, we decided to investigate whether PPAR␥ could be involved in transcriptional induction of RevErb␣ expression in adipocytes. Furth...

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Section: Discussionmentioning

confidence: 99%

The Orphan Nuclear Receptor Rev-Erbα Is a Peroxisome Proliferator-activated Receptor (PPAR) γ Target Gene and Promotes PPARγ-induced Adipocyte Differentiation

Fontaine

Dubois

Duguay

et al. 2003

Journal of Biological Chemistry

219

179

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“…Furthermore, the significant impact on myokine expression that regulates inflammation, lipolysis, muscle growth, and the accumulation of body fat underscores the potential therapeutic utility of Rev-erb modulation by inverse agonists/antagonists. However, identification of small molecule regulators will be hindered by the lack of a significant pocket in the ligand binding domain in the Rev-erb/ NR1D subgroup of orphan nuclear receptors (51).…”

Section: Figmentioning

confidence: 99%

Rev-erbβ Regulates the Expression of Genes Involved in Lipid Absorption in Skeletal Muscle Cells

Ramakrishnan

Lau

Burke

et al. 2005

Journal of Biological Chemistry

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Rev-erb␤ is an orphan nuclear receptor that selectively blocks trans-activation mediated by the retinoic acid-related orphan receptor-␣ (ROR␣). ROR␣ has been implicated in the regulation of high density lipoprotein cholesterol, lipid homeostasis, and inflammation. Reverb␤ and ROR␣ are expressed in similar tissues, including skeletal muscle; however, the pathophysiological function of Rev-erb␤ has remained obscure. We hypothesize from the similar expression patterns, target genes, and overlapping cognate sequences of these nuclear receptors that Rev-erb␤ regulates lipid metabolism in skeletal muscle. This lean tissue accounts for >30% of total body weight and 50% of energy expenditure. Moreover, this metabolically demanding tissue is a primary site of glucose disposal, fatty acid oxidation, and cholesterol efflux. Consequently, muscle has a significant role in insulin sensitivity, obesity, and the blood-lipid profile. We utilize ectopic expression in skeletal muscle cells to understand the regulatory role of Rev-erb␤ in this major mass peripheral tissue. Exogenous expression of a dominant negative version of mouse Rev-erb␤ decreases the expression of many genes involved in fatty acid/lipid absorption (including Cd36, and Fabp-3 and -4). Interestingly, we observed a robust induction (>15-fold) in mRNA expression of interleukin-6, an "exerciseinduced myokine" that regulates energy expenditure and inflammation. Furthermore, we observed the dramatic repression (>20-fold) of myostatin mRNA, another myokine that is a negative regulator of muscle hypertrophy and hyperplasia that impacts on body fat accumulation. This study implicates Rev-erb␤ in the control of lipid and energy homoeostasis in skeletal muscle. In conclusion, we speculate that selective modulators of Rev-erb␤ may have therapeutic utility in the treatment of dyslipidemia and regulation of muscle growth. Members of the nuclear receptor (NR)1 superfamily bind to specific DNA elements and function as transcriptional regulators (1, 2). In addition to the ligand-activated NRs, many members within this superfamily have no known ligand, and are referred to as "orphan NRs" (3). The orphan receptor Rev-erb␤ (NR1D2, also known as Rev-erb␣-related receptor, RVR) belongs to the family of "Reverbs" that also contain Rev-erb␣ (4, 5). The primary structure of these two receptors together with retinoic acid-related orphan receptor-␣ (ROR␣) and the Drosophila orphan receptor, E75A, is very similar especially in the DNA-binding domain and the putative ligand-binding domain (6).Two Rev-erb␤ genes have been identified; Rev-erb␤1 and Rev-erb␤2, which are alternatively spliced products of the Reverb␤ gene (7). The mRNA expression data shows that Rev-erb␤ is abundantly expressed in most tissues, although higher levels of expression are observed in skeletal muscle, brain, kidney, and liver (Refs. 4 and 8 and references therein).Rev-erb␣, Rev-erb␤, and ROR bind as monomers to the nuclear receptor half-site motif, PuGGTCA flanked 5Ј by an ATrich sequence ((A/T) 6 PuGGTCA). Although...

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“…ROR and Rev-erb share 58% and 37% identical amino acids in the C and E domains respectively. Rev-erbs have no known ligand, lack the AF2-activating domain (AF2-AD) region that is necessary for coactivator binding, bind to DNA as monomers or homodimers, and constitutively repress transcription when bound on their responsive element, known as RevRE (recognized by the monomeric form) or RevDR2 (bound by the homodimer) (Harding & Lazar 1995, Adelmant et al 1996, Renaud et al 2000. In contrast to Rev-erbs, ROR orphan receptors act as constitutive transcriptional activators in the absence of exogenously added ligand through monomeric DNA response elements that are extremely similar to the RevRE.…”

Section: Introductionmentioning

confidence: 99%

A specific and unusual nuclear localization signal in the DNA binding domain of the Rev-erb orphan receptors

Chopin-Delannoy¹,

Thénot²,

Delaunay³

et al. 2003

Journal of Molecular Endocrinology

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The orphan receptors Rev-erbα and Rev-erbβ are members of the nuclear receptors superfamily and act as transcriptional repressors. Rev-erbα is expressed with a robust circadian rhythm and is involved in liver metabolism through repression of the ApoA1 gene, but no role has been yet defined for Rev-erbβ. To gain better understanding of their function and mode of action, we characterized the proteins encoded by these two genes. Both Rev-erbα and Rev-erbβ proteins were nuclear when transiently transfected in COS-1 cells. The major nuclear location signal (NLS) of Rev-erbα is in the amino-terminal region of the protein. Fusion of green fluorescent protein (GFP) to the amino terminus of Rev-erbα deletion mutants showed that the NLS is located whithin a 53 amino acid segment of the DNA binding domain (DBD). The homologous region of Rev-erbβ fused to GFP also targeted the fusion protein to the nucleus, suggesting that the location of this NLS is conserved among all the Rev-erb group members. Interestingly, members of the phylogenetically closest nuclear orphan receptor group (ROR), which exhibit 58% amino acid identity with Rev-erb in the DBD, do not have their NLS located whithin the DBD. GFP/DBD.RORα or GFP/DBD.RORβ remained cytoplasmic, in contrast to GFP/DBD.Rev-erb fusion proteins. Alignment of human Rev-erb and ROR DBD amino acid sequences predicted that the two basic residues, K167 and R168, located just upstream from the second zinc finger, could play a critical part in the nuclear localization of Rev-erb proteins. Substitution of these two residues with those found in ROR, in the GFP/DBD.Rev-erb context, resulted in cytoplasmic proteins. In contrast, the reverse mutation of the GFP/DBD.RORα towards the Rev-erbα residues targeted the fusion protein to the nucleus. Our data demonstrate that Rev-erb proteins contain a functional NLS in the DBD. Its location is unusual within the nuclear receptor superfamily and suggests that Rev-erb orphan receptors control their intracellular localization via a mechanism different from that of other nuclear receptors.

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Structure-Function Analysis of the Rev-erbA and RVR Ligand-Binding Domains Reveals a Large Hydrophobic Surface That Mediates Corepressor Binding and a Ligand Cavity Occupied by Side Chains

Cited by 49 publications

References 55 publications

The Orphan Nuclear Receptor Rev-Erbα Is a Peroxisome Proliferator-activated Receptor (PPAR) γ Target Gene and Promotes PPARγ-induced Adipocyte Differentiation

The Orphan Nuclear Receptor Rev-Erbα Is a Peroxisome Proliferator-activated Receptor (PPAR) γ Target Gene and Promotes PPARγ-induced Adipocyte Differentiation

Rev-erbβ Regulates the Expression of Genes Involved in Lipid Absorption in Skeletal Muscle Cells

A specific and unusual nuclear localization signal in the DNA binding domain of the Rev-erb orphan receptors

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