The adhesion G protein-coupled receptor GPR56 is a cell-autonomous regulator of oligodendrocyte development.
Ontology highlight
ABSTRACT:
SUBMITTER: Giera S
PROVIDER: S-EPMC4302951 | biostudies-literature |
REPOSITORIES: biostudies-literature
Similar Datasets
Project description:GPR56 is an adhesion G protein-coupled receptor that plays a key role in cortical development. Mutations to GPR56 in humans cause malformations of the cerebral cortex, but little is known about the normal function of the receptor. We found that the large N terminus (NT) of GPR56 is cleaved from the rest of the receptor during processing but remains non-covalently associated with the seven-transmembrane region of the receptor, as indicated by coimmunoprecipitation of the two GPR56 fragments from both transfected cells and native tissue. We also found that truncation of the GPR56 NT results in constitutive activation of receptor signaling, as revealed by increased GPR56-stimulated signaling upon transfection of HEK-293 cells with truncated GPR56, greatly enhanced binding of β-arrestins by truncated GPR56 relative to the full-length receptor, extensive ubiquitination of truncated GPR56, and cytotoxicity induced by truncated GPR56 that could be rescued by cotransfection of cells with β-arrestin 2. Furthermore, we found that the GPR56 NT is capable of homophilic trans-trans interactions that enhance receptor signaling activity. On the basis of these findings, we suggest a model of receptor activation in which the large N terminus of GPR56 constrains receptor activity but N-terminal interactions (GPR56 NT with an extracellular ligand and/or GPR56 NT homophilic trans-trans associations) can remove this inhibitory influence of the N terminus to activate receptor signaling.
| S-EPMC3190698 | biostudies-literature
Project description:GPR56 is a widely expressed adhesion GPCR (AGPCR) that has pleotropic roles in brain development, platelet function, cancer, and more. Nearly all AGPCRs possess extracellular regions that bind protein ligands and conceal a cryptic tethered peptide agonist. AGPCR reception of mechanical or shear force is thought to release the tethered agonist permitting its binding to the AGPCR orthosteric site for consequent activation of G protein signaling. This multistep mechanism of AGPCR activation is difficult to target, emphasizing the need for tool compounds and potential therapeutics that modulate AGPCRs directly. We expanded our cell-based pilot screen for GPR56 small molecule activators to screen >200,000 compounds and identified two promising agonists: 2-(furan-2-yl)-1-[(4-phenylphenyl)carbonyl]pyrrolidine, or compound 4, and propan-2-yl-4-(2-bromophenyl)-2,7,7-trimethyl-5-oxo-1,4,5,6,7,8-hexahydroquinoline-3-carboxylate, or compound 36. Both compounds activated GPR56 receptors enginered to have impaired tethered agonists and/or be cleavage deficient. Compound 4 activated a subset of group VIII AGPCRs while compound 36 had exclusive specificity for GPR56 among the GPCRs tested. Compound 36 SAR analysis identified an analog with the isopropyl R group replaced with a cyclopentyl ring and the electrophilic bromine replaced with a CF3 group. Analog 36.40 had 40% increased potency over compound 36 and was 20-fold more potent than synthetic peptidomimetics designed from the GPR56 tethered agonist. The new GPCR56 tool compounds discovered in this screen may be used to further advance understanding of GPR56 function and aid development of AGPCR-targeted therapeutics. SIGNIFICANCE STATEMENT: Adhesion G protein coupled receptors (AGPCRs) are a large, clinically relevant class of GPCRs with no available therapeutics, in part due to their unique mechanism of activation. GPR56 is a widely expressed model AGPCR involved in cancer metastasis, hemostasis, and neuron myelination. In the present study, we identified novel small molecule agonists for GPR56. These molecules are among the most potent identified thus far and may become useful leads in the development of a GPR56-targeted therapeutic.
| S-EPMC10289240 | biostudies-literature
Project description:Metastatic growth is considered a rate-limiting step in cancer progression, and upregulation of extracellular matrix (ECM) deposition and cell-ECM signaling are major drivers of this process. Mechanisms to reverse ECM upregulation in cancer could potentially facilitate its prevention and treatment but they are poorly understood. We previously reported that the adhesion G-protein-coupled receptor GPR56/ADGRG1 is downregulated in melanoma metastases. Its re-expression inhibited melanoma growth and metastasis and reduced the deposition of fibronectin, a major ECM component. We hypothesize that its effect on fibronectin deposition contributes to its inhibitory role on metastatic growth. To test this, we investigated the function of GPR56 on cell-fibronectin adhesion and its relationship with metastatic growth in melanoma. Our results reveal that GPR56 inhibits melanoma metastatic growth by impeding the expansion of micrometastases to macrometastases. Meanwhile, we present evidence that GPR56 inhibits fibronectin deposition and its downstream signaling, such as phosphorylation of focal adhesion kinase (FAK), during this process. Administration of the FAK inhibitor Y15 perturbed the proliferation of melanoma metastases, supporting a causative link between the cell adhesion defect induced by GPR56 and its inhibition of metastatic growth. Taken together, our results suggest that GPR56 in melanoma metastases inhibits ECM accumulation and adhesion, which contributes to its negative effects on metastatic growth.
| S-EPMC5799216 | biostudies-literature
Project description:GPR56 is a member of the adhesion G protein-coupled receptor (GPCR) family. Despite the importance of GPR56 in brain development, where mutations cause a devastating human brain malformation called bilateral frontoparietal polymicrogyria (BFPP), the signaling mechanism(s) remain largely unknown. Like many other adhesion GPCRs, GPR56 is cleaved via a GPCR autoproteolysis-inducing (GAIN) domain into N- and C-terminal fragments (GPR56N and GPR56C); however, the biological significance of this cleavage is elusive. Taking advantage of the recent identification of a GPR56 ligand and the presence of BFPP-associated mutations, we investigated the molecular mechanism of GPR56 signaling. We demonstrate that ligand binding releases GPR56N from the membrane-bound GPR56C and triggers the association of GPR56C with lipid rafts and RhoA activation. Furthermore, one of the BFPP-associated mutations, L640R, does not affect collagen III-induced lipid raft association of GPR56. Instead, it specifically abolishes collagen III-mediated RhoA activation. Together, these findings reveal a novel signaling mechanism that may apply to other members of the adhesion GPCR family.
| S-EPMC4065004 | biostudies-literature
Project description:In the vertebrate central nervous system, myelinating oligodendrocytes are postmitotic and derive from proliferative oligodendrocyte precursor cells (OPCs). The molecular mechanisms that govern oligodendrocyte development are incompletely understood, but recent studies implicate the adhesion class of G protein-coupled receptors (aGPCRs) as important regulators of myelination. Here, we use zebrafish and mouse models to dissect the function of the aGPCR Gpr56 in oligodendrocyte development. We show that gpr56 is expressed during early stages of oligodendrocyte development. In addition, we observe a significant reduction of mature oligodendrocyte number and myelinated axons in gpr56 zebrafish mutants. This reduction results from decreased OPC proliferation, rather than increased cell death or altered neural precursor differentiation potential. Finally, we show that these functions are mediated by G?12/13 proteins and Rho activation. Together, our data establish Gpr56 as a regulator of oligodendrocyte development.
| S-EPMC4302765 | biostudies-literature
Project description:While the formation of myelin by oligodendrocytes is critical for the function of the central nervous system, the molecular mechanism controlling oligodendrocyte differentiation remains largely unknown. Here we identify G protein-coupled receptor 37 (GPR37) as an inhibitor of late-stage oligodendrocyte differentiation and myelination. GPR37 is enriched in oligodendrocytes and its expression increases during their differentiation into myelin forming cells. Genetic deletion of Gpr37 does not affect the number of oligodendrocyte precursor cells, but results in precocious oligodendrocyte differentiation and hypermyelination. The inhibition of oligodendrocyte differentiation by GPR37 is mediated by suppression of an exchange protein activated by cAMP (EPAC)-dependent activation of Raf-MAPK-ERK1/2 module and nuclear translocation of ERK1/2. Our data suggest that GPR37 regulates central nervous system myelination by controlling the transition from early-differentiated to mature oligodendrocytes.
| S-EPMC4792952 | biostudies-literature
Project description:Mutations in GPR56, an orphan G-protein-coupled receptor (GPCR), cause bilateral frontoparietal polymicrogyria (BFPP), a disorder characterized by mental retardation, seizures, motor developmental delay, and ataxia. BFPP patients have structural abnormalities of the cerebral cortex, cerebellum, and pons. To shed light on the function of GPR56 and the anatomical and behavioral defects underlying BFPP, we analyzed the cerebellum of mice lacking this GPCR. Gpr56(-/-) mice display a severe malformation of the rostral cerebellum that develops perinatally. Defects involve fusion of adjacent lobules, disrupted layering of neurons and glia, and fragmentation of the pial basement membrane. At the age of defect onset, GPR56 expression is restricted specifically to developing granule cells in the rostral cerebellum, suggesting that GPR56 regulates properties of these cells. Indeed, granule cells from the rostral region of perinatal Gpr56(-/-) cerebella show loss of adhesion to extracellular matrix molecules of the pial basement membrane. Interference RNA-mediated knockdown of GPR56 recapitulates the loss of adhesion seen in knock-outs, and reexpression of GPR56 rescues the adhesion defect in knock-out granule cells. Loss of GPR56 does not affect cell proliferation, migration, or neurite outgrowth. These studies establish a novel role for GPR56 in the adhesion of developing neurons to basal lamina molecules and suggest that this adhesion is critical for maintenance of the pia and proper cerebellar morphogenesis.
| S-EPMC2744696 | biostudies-other
Project description:Mutations in the G protein–coupled receptor GPR126/ADGRG6 cause human diseases, including defective peripheral nervous system (PNS) myelination. To study GPR126 function, we generated new genetic mice and zebrafish models. Murine Gpr126 is expressed in developing heart endocardium, and global Gpr126 inactivation is embryonically lethal, with mutants having thin-walled ventricles but unaffected heart patterning or maturation. Endocardial-specific Gpr126 deletion does not affect heart development or function, and transgenic endocardial GPR126 expression fails to rescue lethality in Gpr126-null mice. Zebrafish gpr126 mutants display unaffected heart development. Gpr126 is also expressed in placental trophoblast giant cells. Gpr126-null mice with a heterozygous placenta survive but exhibit GPR126-defective PNS phenotype. In contrast, Gpr126-null embryos with homozygous mutant placenta die but are rescued by placental GPR126 expression. Gpr126-deficient placentas display down-regulation of preeclampsia markers Mmp9, Cts7, and Cts8. We propose that the placenta-heart axis accounts for heart abnormalities secondary to placental defects in Gpr126 mutants.
| S-EPMC8589310 | biostudies-literature
Project description:The G protein-coupled receptor (GPCR) superfamily is the largest known receptor family in the human genome. Although the family of adhesion GPCRs comprises the second largest sub-family, their function is poorly understood. Here, we review the current knowledge about the adhesion GPCR family member GPR126. GPR126 possesses a signal peptide, a 7TM domain homologous to secretin-like GPCRs, a GPS motif and an extended N-terminus containing a CUB (Complement, Uegf, Bmp1) domain, a PTX (Pentraxin) domain, a hormone binding domain and 27 putative N-glycosylation sites. Knockdown and knockout experiments in zebrafish and mice have demonstrated that Gpr126 plays an essential role in neural, cardiac and ear development. In addition, genome-wide association studies have implicated variations at the GPR126 locus in obstructive pulmonary dysfunction, in scoliosis and as a determinant of trunk length and body height. Gpr126 appears to exert its function depending on the organ system via G protein- and/or N-terminus-dependent signaling. Here, we review the current knowledge about Gpr126, which, due to the variety of its functions and its multiple signaling modalities, provides a model adhesion GPCR to understand general functional concepts utilized by adhesion GPCRs.
| S-EPMC4258410 | biostudies-literature
Project description:GPR56 is a member of the adhesion G-protein-coupled receptor family shown to play important roles in cell adhesion, brain development, immune function, and tumorigenesis. GPR56 is highly upregulated in colorectal cancer and correlates with poor prognosis. Several studies have shown GPR56 couples to the Gα12/13 class of heterotrimeric G-proteins to promote RhoA activation. However, due to its structural complexity and lack of a high-affinity receptor-specific ligand, the complete GPR56 signaling mechanism remains largely unknown. To delineate the activation mechanism and intracellular signaling functions of GPR56, we generated a monoclonal antibody (mAb) that binds with high affinity and specificity to the extracellular domain (ECD). Using deletion mutants, we mapped the mAb binding site to the GAIN domain, which mediates membrane-proximal autoproteolytic cleavage of the ECD. We showed that GPR56 overexpression in 293T cells leads to increased phosphorylation of Src, Fak, and paxillin adhesion proteins and activation of the Gα12/13-RhoA-mediated serum response factor (SRF) pathway. Treatment with the mAb potentiated Src-Fak phosphorylation, RhoA-SRF signaling, and cell adhesion. Consistently, GPR56 knockdown in colorectal cancer cells decreased Src-Fak pathway phosphorylation and cell adhesion. Interestingly, GPR56-mediated activation of Src-Fak phosphorylation occurred independent of RhoA, yet mAb-induced potentiation of RhoA-SRF signaling was Src-dependent. Furthermore, we show that the C-terminal portion of the Serine-Threonine-Proline-rich (STP) region, adjacent to the GAIN domain, was required for Src-Fak activation. However, autoproteolytic cleavage of the ECD was dispensable. These data support a new ECD-dependent mechanism by which GPR56 functions to regulate adhesion through activation of Src-Fak signaling.
| S-EPMC7948743 | biostudies-literature