Fndc4, a highly identical ortholog of Irisin binds and activates a novel orphan receptor G-protein coupled receptor

We report the first pharmacological tool agonist for in vitro characterization of the orphan receptor GPR132, preliminary structure–activity relationships based on 32 analogs and a suggested binding mode from docking.

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Molecular cloning of an orphan G-protein-coupled receptor that constitutively activates adenylate cyclase

Biochemical Journal ◽

10.1042/bj3090837 ◽

1995 ◽

Vol 309 (3) ◽

pp. 837-843 ◽

Cited By ~ 81

Author(s):

D Eggerickx ◽

J F Denef ◽

O Labbe ◽

Y Hayashi ◽

S Refetoff ◽

...

Keyword(s):

Adenylate Cyclase ◽

G Protein ◽

Rnase Protection Assay ◽

Biological Significance ◽

Orphan Receptor ◽

Constitutive Activity ◽

G Protein Coupled Receptor ◽

Rnase Protection ◽

G Protein Coupled ◽

Stimulation Of

A human gene encoding an orphan G-protein-coupled receptor named ACCA (adenylate cyclase constitutive activator) was isolated from a genomic library using as a probe a DNA fragment obtained by low-stringency PCR. Human ACCA (hACCA) is a protein of 330 amino acids that exhibits all the structural hallmarks of the main family of G-protein-coupled receptors. Expression of hACCA resulted in a dramatic stimulation of adenylate cyclase, similar in amplitude to that obtained with other Gs-coupled receptors fully activated by their respective ligands. This stimulation was obtained in a large variety of stable cell lines derived from various organs, and originating from different mammalian species. hACCA was found to be the human homologue of a recently reported mouse orphan receptor (GPCR21). The mouse ACCA (mACCA) was therefore recloned by PCR, and expression of mACCA in Cos-7 cells demonstrated that the mouse receptor behaved similarly as a constitutive activator of adenylate cyclase. It is not known presently whether the stimulation of adenylate cyclase is the result of a true constitutive activity of the receptor or, alternatively, is the consequence of a permanent stimulation by a ubiquitous ligand. The tissue distribution of mACCA was determined by RNase protection assay. Abundant transcripts were found in the brain, whereas lower amounts were detected in testis, ovary and eye. Various hypotheses concerning the constitutive activity of ACCA and their potential biological significance are discussed.

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Evidence for Differential Regulation of GnRH Signaling via Heterodimerization among GnRH Receptor Paralogs in the Protochordate, Ciona intestinalis

Endocrinology ◽

10.1210/en.2011-1668 ◽

2012 ◽

Vol 153 (4) ◽

pp. 1841-1849 ◽

Cited By ~ 19

Author(s):

Tsubasa Sakai ◽

Masato Aoyama ◽

Tsuyoshi Kawada ◽

Takehiro Kusakabe ◽

Motoyuki Tsuda ◽

...

Keyword(s):

Signaling Pathways ◽

G Protein ◽

Ciona Intestinalis ◽

Orphan Receptor ◽

Receptor Subtype ◽

Camp Production ◽

G Protein Coupled Receptor ◽

Gi Protein ◽

Species Specific ◽

G Protein Coupled

The endocrine and neuroendocrine systems for reproductive functions have diversified as a result of the generation of species-specific paralogs of peptide hormones and their receptors including GnRH and their receptors (GnRHR), which belong to the class A G protein-coupled receptor family. A protochordate, Ciona intestinalis, has been found to possess seven GnRH (tGnRH-3 to -8 and Ci-GnRH-X) and four GnRHR (Ci-GnRHR1 to -4). Moreover, Ci-GnRHR4 (R4) does not bind to any Ciona GnRH and activate any signaling pathways. Here we show novel functional diversification of GnRH signaling pathways via G protein-coupled receptor heterodimerization among Ciona GnRHR. R4 was shown to heterodimerize with R2 specifically in test cells of vitellogenic oocytes by coimmunoprecipitation. The R2-R4 heterodimerization in human embryonic kidney 293 cells cotransfected with R2 and R4 was also observed by coimmunoprecipitation and fluorescent energy transfer analyses. Of particular interest is that the R2-R4 heterodimer decreases the cAMP production in a nonligand-selective manner via shift of activation of Gs protein to Gi protein by R2, compared with R2 monomer/homodimer. Considering that the R1-R4 heterodimer elicits 10-fold more potent Ca2+ mobilization than R1 monomer/homodimer in a ligand-selective manner but does not affect cAMP production, these results indicate that R4 regulates differential GnRH signaling cascades via heterodimerization with R1 and R2 as an endogenous allosteric modulator. Collectively, the present study suggests that the heterodimerization among GnRHR paralogs, including the species-specific orphan receptor subtype, is involved in rigorous and diversified GnRHergic signaling of the protochordate, which lacks a hypothalamus-pituitary gonad axis.

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In Pursuit of Leucine-Rich Repeat-Containing G Protein-Coupled Receptor-5 Regulation and Function in the Uterus

Endocrinology ◽

10.1210/en.2009-0690 ◽

2009 ◽

Vol 150 (11) ◽

pp. 5065-5073 ◽

Cited By ~ 20

Author(s):

Xiaofei Sun ◽

Lindsey Jackson ◽

Sudhansu K. Dey ◽

Takiko Daikoku

Keyword(s):

Wnt Signaling ◽

G Protein ◽

Hair Follicles ◽

Uterine Epithelium ◽

Orphan Receptor ◽

Leucine Rich Repeat ◽

G Protein Coupled Receptor ◽

Ovariectomized Mice ◽

Lgr5 Expression ◽

G Protein Coupled

Leucine-rich repeat-containing G protein-coupled receptor (LGR)-5 is a recently identified marker of stem cells in adult intestinal epithelium and hair follicles. Because of this characteristic, we studied the status of Lgr5 expression in the mouse uterus under various conditions. Lgr5 is highly expressed in the uterine epithelium of immature mice and is dramatically down-regulated after the mice resume estrous cycles. Surprisingly, whereas its expression is up-regulated in uteri of ovariectomized mice, the expression is down-regulated by estrogen and progesterone via their cognate nuclear receptors, estrogen receptor-α and progesterone receptor, respectively. Using a mouse endometrial cancer model, we also found that Lgr5 is highly expressed in the epithelium during the initial stages of tumorigenesis but is remarkably down-regulated in fully developed tumors. Lgr5 is a downstream target of Wnt signaling in the intestine. Genetic evidence shows that either excessive or absence of Wnt signaling dampens Lgr5 expression in the uterus. Collectively, our results show that Lgr5 expression in the mouse uterine epithelium is unique and dynamically regulated under various physiological and pathological states of the uterus, suggesting that this orphan receptor has important functions in uterine biology. However, identifying definitive uterine function of LGR5 will require further investigation using conditional deletion of uterine Lgr5 because systemic deletion of this gene is neonatally lethal.

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ThermoFRET: A novel nanoscale G protein coupled receptor thermostability assay functional in crude solubilised membrane preparations

10.1101/2020.07.07.191957 ◽

2020 ◽

Author(s):

David N Tippett ◽

Brad Hoare ◽

Tamara Miljus ◽

David A Sykes ◽

Dmitry B. Veprintsev

Keyword(s):

Drug Discovery ◽

Protein Purification ◽

G Protein ◽

High Throughput ◽

Thermal Denaturation ◽

Protein Unfolding ◽

Orphan Receptor ◽

G Protein Coupled Receptor ◽

G Protein Coupled

AbstractSensitive protein stability assays for membrane proteins are crucial for developing purification protocols, for structural and biophysical characterisation and drug discovery. Here, we describe a novel high-throughput 384-well FRET-based thermostability methodology, ThermoFRET, allowing for the ultrasensitive determination of G protein coupled receptor (GPCR) stability. This method measures FRET between a terbium-cryptate labelled GPCR and BODIPY-FL-Cystine, a thiolreactive dye that reacts with cysteine residues exposed upon protein unfolding in response to thermal denaturation. ThermoFRET is functional in crude solubilised membrane preparations, without protein purification and can detect receptor stabilising ligands, making it ideally suited for orphan receptor screening.

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Evidence for Protein–Protein Interaction between Dopamine Receptors and the G Protein-Coupled Receptor 143

International Journal of Molecular Sciences ◽

10.3390/ijms22158328 ◽

2021 ◽

Vol 22 (15) ◽

pp. 8328

Author(s):

Beatriz Bueschbell ◽

Prashiela Manga ◽

Erika Penner ◽

Anke C. Schiedel

Keyword(s):

Side Effects ◽

G Protein ◽

Protein Interactions ◽

Multiple Roles ◽

Orphan Receptor ◽

Pigment Cells ◽

Protein Protein Interactions ◽

G Protein Coupled Receptor ◽

Protein Protein Interaction ◽

G Protein Coupled

Protein-protein interactions between G protein-coupled receptors (GPCRs) can augment their functionality and increase the repertoire of signaling pathways they regulate. New therapeutics designed to modulate such interactions may allow for targeting of a specific GPCR activity, thus reducing potential for side effects. Dopamine receptor (DR) heteromers are promising candidates for targeted therapy of neurological conditions such as Parkinson’s disease since current treatments can have severe side effects. To facilitate development of such therapies, it is necessary to identify the various DR binding partners. We report here a new interaction partner for DRD2 and DRD3, the orphan receptor G protein-coupled receptor 143 (GPR143), an atypical GPCR that plays multiple roles in pigment cells and is expressed in several regions of the brain. We previously demonstrated that the DRD2/ DRD3 antagonist pimozide also modulates GPR143 activity. Using confocal microscopy and two FRET methods, we observed that the DRs and GPR143 colocalize and interact at intracellular membranes. Furthermore, co-expression of wildtype GPR143 resulted in a 57% and 67% decrease in DRD2 and DRD3 activity, respectively, as determined by β-Arrestin recruitment assay. GPR143-DR dimerization may negatively modulate DR activity by changing affinity for dopamine or delaying delivery of the DRs to the plasma membrane.

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