mthl1, a potential Drosophila homologue of mammalian adhesion GPCRs, is involved in antitumor reactions to injected oncogenic cells in flies.

Injection of OCs into adult male flies induces a strong transcriptomic response in the host flies featuring in particular genes encoding bona fide G coupled proteins, among which the gene for methuselah like 1 is prominent. The injection is followed after a 3-d lag period, by the proliferation of the oncogenic cells. We hypothesized that through the product of mthl1 the host might control, at least in part, this proliferation as a defense reaction. Through a combination of genetic manipulations of the mthl1 gene (loss of function and overexpression of mthl1), we document that indeed this gene has an antiproliferative effect. Parallel injections of primary embryonic Drosophila cells or of various microbes do not exhibit this effect. We further show that mthl1 controls the expression of a large number of genes coding for chemoreceptors and genes implicated in regulation of development. Of great potential interest is our observation that the expression of the mouse gene coding for the adhesion G-protein-coupled receptor E1 (Adgre1, also known as F4/80), a potential mammalian homologue of mthl1, is significantly induced by B16-F10 melanoma cell inoculation 3 d postinjection in both the bone marrow and spleen (nests of immature and mature myeloid-derived immune cells), respectively. This observation is compatible with a role of this GPCR in the early response to injected tumor cells in mice.

GPR114/ADGRG5 is activated by its tethered peptide agonist because it is a cleaved adhesion GPCR.

Family B2 or adhesion G protein-coupled receptors (AGPCRs) are distinguished by variable extracellular regions that contain a modular protease, termed the GPCR autoproteolysis-inducing domain that self-cleaves the receptor into an N-terminal fragment (NTF) and a C-terminal fragment (CTF), or seven transmembrane domain (7TM). The NTF and CTF remain bound after cleavage through noncovalent interactions. NTF binding to a ligand(s) presented by nearby cells, or the extracellular matrix anchors the NTF, such that cell movement generates force to induce NTF/CTF dissociation and expose the AGPCR tethered peptide agonist. The released tethered agonist (TA) binds rapidly to the 7TM orthosteric site to activate signaling. The orphan AGPCR, GPR114 was reported to be uncleaved, yet paradoxically capable of activation by its TA. GPR114 has an identical cleavage site and TA to efficiently cleave GPR56. Here, we used immunoblotting and biochemical assays to demonstrate that GPR114 is a cleaved receptor, and the self-cleavage is required for GPR114 TA-activation of Gs and no other classes of G proteins. Mutagenesis studies defined features of the GPR114 and GPR56 GAINA subdomains that influenced self-cleavage efficiency. Thrombin treatment of protease-activated receptor 1 leader/AGPCR fusion proteins demonstrated that acute decryption of the GPR114/56 TAs activated signaling. GPR114 was found to be expressed in an eosinophilic-like cancer cell line (EoL-1 cells) and endogenous GPR114 was efficiently self-cleaved. Application of GPR114 TA peptidomimetics to EoL-1 cells stimulated cAMP production. Our findings may aid future delineation of GPR114 function in eosinophil cAMP signaling related to migration, chemotaxis, or degranulation.

The dimerized pentraxin-like domain of the adhesion G protein-coupled receptor 112 (ADGRG4) suggests function in sensing mechanical forces.

Adhesion G protein-coupled receptors (aGPCRs) feature large extracellular regions with modular domains that often resemble protein classes of various function. The pentraxin (PTX) domain, which is predicted by sequence homology within the extracellular region of four different aGPCR members, is well known to form pentamers and other oligomers. Oligomerization of GPCRs is frequently reported and mainly driven by interactions of the seven-transmembrane region and N or C termini. While the functional importance of dimers is well-established for some class C GPCRs, relatively little is known about aGPCR multimerization. Here, we showcase the example of ADGRG4, an orphan aGPCR that possesses a PTX-like domain at its very N-terminal tip, followed by an extremely long stalk containing serine-threonine repeats. Using X-ray crystallography and biophysical methods, we determined the structure of this unusual PTX-like domain and provide experimental evidence for a homodimer equilibrium of this domain which is Ca2+-independent and driven by intermolecular contacts that differ vastly from the known soluble PTXs. The formation of this dimer seems to be conserved in mammalian ADGRG4 indicating functional relevance. Our data alongside of theoretical considerations lead to the hypothesis that ADGRG4 acts as an in vivo sensor for shear forces in enterochromaffin and Paneth cells of the small intestine.

GPR56 C-terminal fragment mediates signal received by N-terminal fragment of another adhesion GPCR Latrophilin1 in neurons.

Adhesion GPCRs (aGPCRs) are a subfamily of GPCRs that are involved in cell adhesion, cell proliferation, and cell migration in various tissues. G protein-coupled receptor proteolytic site (GPS) of aGPCR is required to cleave the extracellular domain autocatalytically, generating two fragments; a N-terminal fragment (NTF) and a C-terminal fragment (CTF) containing seven transmembrane structure. NTF can interact with CTF non-covalently after cleavage, however the physiological significance of the cleavage of aGPCR at GPS, and also the interaction between NTF and CTF have not been fully clarified yet. In this study, we first investigated the expression profiles of two aGPCRs, GPR56/ADGRG1, and LPHN1/ADGRL1 in mouse brain, and found that the NTF and CTF of GPR56 independently expressed in different brain region at different developmental stages. Immunoprecipitation of GPR56CTF co-immunoprecipitated LPHN1NTF from mouse brain and HEK293T cells expressing both fragments. Stimulation with LPHN1 ligand, α-Latrotoxin N4C (αLTXN4C), to cells expressing LPHN1NTF and GPR56CTF increased intracellular Ca2+ concentration ([Ca2+ ]i). We also demonstrated that GPR56KO mouse neurons attenuated their Ca2+ response to αLTXN4C. These results suggest the possibility of functional and chimeric complex containing LPHN1NTF and GPR56CTF in neuronal signal transduction.

Loss of Adgra3 causes obstructive azoospermia with high penetrance in male mice.

The adhesion receptor ADGRA3 (GPR125) is a known spermatogonial stem cell marker, but its impact on male reproduction and fertility has not been examined. Using a mouse model lacking Adgra3 (Adgra3-/- ), we show that 55% of the male mice are infertile from puberty despite having normal spermatogenesis and epididymal sperm count. Instead, male mice lacking Adgra3 exhibited decreased estrogen receptor alpha expression and transient dilation of the epididymis. Combined with an increased estradiol production, this indicates a post-pubertal hormonal imbalance and fluid retention. Dye injection revealed a blockage between the ejaculatory duct and the urethra, which is rare in mice suffering from infertility, thereby mimicking the etiologies of obstructive azoospermia found in human male infertility. To summarize, male reproductive tract development is dependent on ADGRA3 function that in concert with estrogen signaling may influence fluid handling during sperm maturation and storage.

Mesenchymal Transglutaminase 2 Activates Epithelial ADAM17: Link to G-Protein-Coupled Receptor 56 (ADGRG1) Signalling.

A wound healing model was developed to elucidate the role of mesenchymal-matrix-associated transglutaminase 2 (TG2) in keratinocyte re-epithelialisation. TG2 drives keratinocyte migratory responses by activation of disintegrin and metalloproteinase 17 (ADAM17). We demonstrate that epidermal growth factor (EGF) receptor ligand shedding leads to EGFR-transactivation and subsequent rapid keratinocyte migration on TG2-positive ECM. In contrast, keratinocyte migration was impaired in TG2 null conditions. We show that keratinocytes express the adhesion G-protein-coupled receptor, ADGRG1 (GPR56), which has been proposed as a TG2 receptor. Using ADAM17 activation as a readout and luciferase reporter assays, we demonstrate that TG2 activates GPR56. GPR56 activation by TG2 reached the same level as observed with an agonistic N-GPR56 antibody. The N-terminal GPR56 domain is required for TG2-regulated signalling response, as the constitutively active C-GPR56 receptor was not activated by TG2. Signalling required the C-terminal TG2 ß-barrel domains and involved RhoA-associated protein kinase (ROCK) and ADAM17 activation, which was blocked by specific inhibitors. Cell surface binding of TG2 to the N-terminal GPR56 domain is rapid and is associated with TG2 and GPR56 endocytosis. TG2 and GPR56 represent a ligand receptor pair causing RhoA and EGFR transactivation. Furthermore, we determined a binding constant for the interaction of human TG2 with N-GPR56 and show for the first time that only the calcium-enabled "open" TG2 conformation associates with N-GPR56.

[Detection of pathogenic gene mutations in thirteen cases of congenital bilateral absence of vas deferens infertility patients].

OBJECTIVE: To detect the cystic fibrosis transmembrane transduction regulator (CFTR) gene mutations and congenital bilateral absence of vas deferens (CBAVD) susceptibility gene mutations in patients with CBAVD, and to explore their association with the risk of CBAVD. METHODS: Whole-exome sequencing and Sanger sequencing validation were conducted on the pathogenic genes CFTR, adhesion G protein-coupled receptor G2 (ADGRG2), sodium channel epithelial 1 subunit beta (SCNN1B), carbonic anhydrase 12 (CA12), and solute carrier family 9 member A3 (SLC9A3) in thirteen cases of isolated CBAVD patients. The polymorphic loci, intron and flanking sequences of CFTR gene were amplified by polymerase chain reaction (PCR) followed by Sanger sequencing. Bioinformatics methods were employed for conservative analysis and deleterious prediction of novel susceptibility gene mutations in CBAVD. Genetic analysis was performed on the pedigree of one out of thirteen patients with CBAVD to evaluate the risk of inheritance in offspring. RESULTS: Exome sequencing revealed CFTR gene exon mutations in only six of the thirteen CBAVD patients, with six missense mutations c.2684G>A(p.Ser895Asn), c.4056G>C(p.Gln1352His), c.2812G>(p.Val938Leu), c.3068T>G(p.Ile1023Arg), c.374T>C(p.Ile125Thr), c.1666A>G(p.Ile556Val)), and one nonsense mutation (c.1657C>T(p.Arg553Ter). Among these six patients, two also had the CFTR homozygous p.V470 site, additionally, mutations in CFTR gene exon regions were not detected in the remaining seven patients. Within the thirteen CBAVD patients, three carried the homozygous p.V470 polymorphic site, four carried the 5T allele, two carried the TG13 allele, and ten carried the c.-966T>G site. Four CBAVD patients simultaneously carried 2-3 of the aforementioned CFTR gene mutation sites. Susceptibility gene mutations in CBAVD among the thirteen patients included one ADGRG2 missense mutation c.2312A>G(p.Asn771Ser), two SLC9A3 missense mutations c.2395T>C(p.Cys799Arg), c.493G>A(p.Val165Ile), one SCNN1B missense mutation c.1514G>A(p.Arg505His), and one CA12 missense mutation c.1061C>T (p.Ala354Val). Notably, the SLC9A3 gene c.493G>A (p.Val165Ile) mutation site was first identified in CBAVD patients. The five mutations exhibited an extremely low population mutation frequency in the gnomAD database, classifying them as rare mutations. Predictions from Mutation Taster and Polyphen-2 software indicated that the harmfulness level of the SLC9A3 gene c.493G>A (p.Val165Ile) site and the SCNN1B gene c.1514G>A (p.Arg505His) site were disease causing and probably damaging. The genetic analysis of one pedigree revealed that the c.1657C>T (p.Arg553Ter) mutation in the proband was a de novo mutation, as neither the proband's father nor mother carried this mutation. The proband and his spouse conceived a daughter through assisted reproductive technology, and the daughter inherited the proband's pathogenic mutation c.1657C>T (p.Arg553Ter). CONCLUSION: CFTR gene mutations remain the leading cause of CBAVD in Chinese patients; however, the distribution and frequency of mutations differ from data reported in other domestic and international studies, highlighting the need to expand the CFTR mutation spectrum in Chinese CBAVD patients. The susceptibility genes ADGRG2, SLC9A3, SCNN1B, and CA12 may explain some cases of CBAVD without CFTR mutations. Given the lack of specific clinical manifestations in CBAVD patients, it is recommended that clinicians conduct further physical examinations and consider scrotal or transrectal ultrasound before making a defi-nitive diagnosis. It is advisable to employ CFTR gene mutation testing in preconception genetic screening to reduce the risk of CBAVD and cystic fibrosis in offspring.

Activation of the adhesion G protein-coupled receptor GPR133 by antibodies targeting its N-terminus.

We recently demonstrated that GPR133 (ADGRD1), an adhesion G protein-coupled receptor involved in raising cytosolic cAMP levels, is necessary for growth of glioblastoma (GBM) and is de novo expressed in GBM relative to normal brain tissue. Our previous work suggested that dissociation of autoproteolytically generated N-terminal and C-terminal fragments of GPR133 at the plasma membrane correlates with receptor activation and signaling. To promote the goal of developing biologics that modulate GPR133 function, we investigated the effects of antibodies against the N-terminus of GPR133 on receptor signaling. Here, we show that treatment of HEK293T cells overexpressing GPR133 with these antibodies increased cAMP levels in a concentration-dependent manner. Analysis of culture medium following antibody treatment further indicated the presence of complexes of these antibodies with the autoproteolytically cleaved N-terminal fragments of GPR133. In addition, cells expressing a cleavage-deficient mutant of GPR133 (H543R) did not respond to antibody stimulation, suggesting that the effect is cleavage dependent. Finally, we demonstrate the antibody-mediated stimulation of WT GPR133, but not the cleavage-deficient H543R mutant, was reproducible in patient-derived GBM cells. These findings provide a paradigm for modulation of GPR133 function with biologics and support the hypothesis that the intramolecular cleavage in the N-terminus modulates receptor activation and signaling.

Disentangling autoproteolytic cleavage from tethered agonist-dependent activation of the adhesion receptor ADGRL3.

Adhesion G protein-coupled receptor latrophilin 3 (ADGRL3), a cell adhesion molecule highly expressed in the central nervous system, acts in synapse formation through trans interactions with its ligands. It is largely unknown if these interactions serve a purely adhesive function or can modulate G protein signaling. To assess how different structural elements of ADGRL3 (e.g., the adhesive domains, autoproteolytic cleavage site, or tethered agonist (TA)) impact receptor function, we require constructs that disrupt specific receptor features without impacting others. While we showed previously that mutating conserved Phe and Met residues in the TA of ADGRL3-C-terminal fragment (CTF), a CTF truncated to the G protein-coupled receptor proteolysis site, abolishes receptor-mediated G protein activation, we now find that autoproteolytic cleavage is disrupted in the full-length version of this construct. To identify a construct that disrupts TA-dependent activity without impacting proteolysis, we explored other mutations in the TA. We found that mutating the sixth and seventh residues of the TA, Leu and Met, to Ala impaired activity in a serum response element activity assay for both full-length and CTF constructs. We confirmed this activity loss results from impaired G protein coupling using an assay that acutely exposes the TA through controlled proteolysis. The ADGRL3 mutant expresses normally at the cell surface, and immunoblotting shows that it undergoes normal autoproteolysis. Thus, we found a construct that disrupts tethered agonism while retaining autoproteolytic cleavage, providing a tool to disentangle these functions in vivo. Our approach and specific findings are likely to be broadly applicable to other adhesion receptors.

Optimization of a peptide ligand for the adhesion GPCR ADGRG2 provides a potent tool to explore receptor biology.

The adhesion GPCR ADGRG2, also known as GPR64, is a critical regulator of male fertility that maintains ion/pH homeostasis and CFTR coupling. The molecular basis of ADGRG2 function is poorly understood, in part because no endogenous ligands for ADGRG2 have been reported, thus limiting the tools available to interrogate ADGRG2 activity. It has been shown that ADGRG2 can be activated by a peptide, termed p15, derived from its own N-terminal region known as the Stachel sequence. However, the low affinity of p15 limits its utility for ADGRG2 characterization. In the current study, we used alanine scanning mutagenesis to examine the critical residues responsible for p15-induced ADGRG2 activity. We next designed systematic strategies to optimize the peptide agonist of ADGRG2, using natural and unnatural amino acid substitutions. We obtained an optimized ADGRG2 Stachel peptide T1V/F3Phe(4-Me) (VPM-p15) that activated ADGRG2 with significantly improved (>2 orders of magnitude) affinity. We then characterized the residues in ADGRG2 that were important for ADGRG2 activation in response to VPM-p15 engagement, finding that the toggle switch W6.53 and residues of the ECL2 region of ADGRG2 are key determinants for VPM-p15 interactions and VPM-p15-induced Gs or arrestin signaling. Our study not only provides a useful tool to investigate the function of ADGRG2 but also offers new insights to guide further optimization of Stachel peptides to activate adhesion GPCR members.

Curcumin activates G protein-coupled receptor 97 (GPR97) in a manner different from glucocorticoid.

Curcumin is a yellow pigment in turmeric (Curcuma longa) with various physiological effects in the body. To elucidate the molecular mechanisms by which bioactive compounds exert their function, identification of their molecular targets is crucial. In this study, we show that curcumin activates G protein-coupled receptor 97 (GPR97). Curcumin dose-dependently activated serum-response element-, but not serum-response factor-response element-, nuclear factor of activated T-cell-response element-, or cAMP-response element-, mediated transcription in cells overexpressed with GPR97. The structure-activity relationship indicated that (i) the double-bonds of the central 7-carbon chain were essential for activation; (ii) a methoxy group on the aromatic ring was required for maximal activity; (iii) the addition of glucuronic acid moiety or a methoxy group to the aromatic ring, but not the methylation of the aromatic p-hydroxy group, eliminated the activity; (iv) the stability of curcumin would be related to receptor activation. Both mutant GPR97(T250A) lacking the cleavage at GPCR proteolysis site and mutant GPR97(ΔN) lacking the N-terminal extracellular region were activated by curcumin and its related compounds similar to wild-type GPR97. In contrast, the synthetic glucocorticoid beclomethasone dipropionate and l-Phe activated wild-type GPR97 and GPR97(T250A), but not GPR97(ΔN). Moreover, curcumin exerted an additive effect on the activation of wild-type GPR97 with beclomethasone dipropionate, but not with l-Phe. Taken together, these results indicate that curcumin activates GPR97 coupled to Gi/Go subunit, and suggest that curcumin and glucocorticoid activate GPR97 in a different manner.

Genetic mutation analysis of 22 patients with congenital absence of vas deferens: a single-center study†.

Congenital absence of the vas deferens (CAVD), a congenital malformation of the male reproductive system, causes obstructive azoospermia and male infertility. Currently, the cystic fibrosis transmembrane conductance regulator (CFTR) has been recognized as the main pathogenic gene in CAVD, with some other genes, such as adhesion G-protein-coupled receptor G2 (ADGRG2), solute carrier family 9 isoform 3 (SLC9A3), sodium channel epithelial 1 subunit beta (SCNN1B), and carbonic anhydrase 12 (CA12), being candidate genes in the pathogenesis of CAVD. However, the frequency and spectrum of these mutations, as well as the pathogenic mechanisms of CAVD, have not been fully investigated. Here, we sequenced all genes with potentially pathogenic mutations using next-generation sequencing and verified all identified variants by Sanger sequencing. Further bioinformatic analysis was performed to predict the pathogenicity of mutations. We described the distribution of the p.V470M, poly-T, and TG-repeat CFTR polymorphisms and identified novel missense mutations in the CFTR and SLC9A3 genes, respectively. Taken together, we identified mutations in the CFTR, ADGRG2, SLC9A3, SCNN1B, and CA12 genes in 22 patients with CAVD, thus broadening the genetic spectrum of Chinese patients with CAVD.

Cell type-specific evaluation of ADGRG1/GPR56 function in developmental central nervous system myelination.

Myelination of axons in the central nervous system (CNS) is a concerted effort between many cell types, resulting in significant cross-talk and communication among cells. Adhesion G protein-coupled receptor ADGRG1 (GPR56) is expressed in all major glial cells and regulates a wide variety of physiological processes by mediating cell-cell and cell-matrix communications. Previous literature has demonstrated the requirement of ADGRG1 in oligodendrocyte precursor cells (OPCs) during developmental myelination. However, it is unknown if ADGRG1 is responsible for myelin formation in a cell-type-specific manner. To that end, here we profiled myelin status in response to deletion of Adgrg1 specifically in OPCs, microglia, astrocytes, and neurons. Interestingly, we find that knocking out Adgrg1 in OPCs significantly decreases OPC proliferation and reduced number of myelinated axons. However, deleting Adgrg1 in microglia, astrocytes, and neurons does not impact developmental myelination. These data support an autonomous functional role for Adgrg1 in OPCs related to myelination.

Characteristics of Retinitis Pigmentosa Associated with ADGRV1 and Comparison with USH2A in Patients from a Multicentric Usher Syndrome Study Treatrush.

In contrast to USH2A, variants in ADGRV1 are a minor cause of Usher syndrome type 2, and the associated phenotype is less known. The purpose of the study was to characterize the retinal phenotype of 18 ADGRV1 patients (9 male, 9 female; median age 52 years) and compare it with that of 204 USH2A patients (111 male, 93 female; median age 43 years) in terms of nyctalopia onset, best corrected visual acuity (BCVA), fundus autofluorescence (FAF), and optical coherence tomography (OCT) features. There was no statistical difference in the median age at onset (30 and 18 years; Mann-Whitney U test, p = 0.13); the mean age when 50% of the patients reached legal blindness (≥1.0 log MAR) based on visual acuity (64 years for both groups; log-rank, p = 0.3); the risk of developing advanced retinal degeneration (patch or atrophy) with age (multiple logistic regression, p = 0.8); or the frequency of cystoid macular edema (31% vs. 26%, Fisher's exact test, p = 0.4). ADGRV1 and USH2A retinopathy were indistinguishable in all major functional and structural characteristics, suggesting that the loss of function of the corresponding proteins produces similar effects in the retina. The results are important for counseling ADGRV1 patients, who represent the minor patient subgroup.

[Gene mutations in congenital bilateral absence of the vas deferens: An update].

Congenital bilateral absence of the vas deferens (CBAVD) is a congenital malformation of the male reproductive system and one of the important causes of obstructive azoospermia and male infertility. It is currently recognized that the main cause of CBAVD is the mutation of the cystic fibrosis transmembrane conductance regulator gene (CFTR). And the mutations of adhesion G protein-coupled receptor G2 (ADGRG2), solute carrier family 9 isoform 3 (SLC9A3) and other genes are also found to be involved in the development and progression of CBAVD. A reasonable CBAVD molecular diagnosis process combined with assisted reproductive technology is currently the most effective method for the diagnosis and treatment of CBAVD, but the offspring of the patient may face the risk of hereditary inheritance. This article focuses on the pathogenesis of CFTR, ADGRG2 and SLC9A3 causing CBAVD, and aims to provide some new ideas for the clinical diagnosis and treatment of CBAVD and CBAVD-related genetic counseling.

Mast cells signal their importance in health and disease.

FcεRI is the primary receptor in mast cells that mediates allergic reactions by inducing rapid release of mediators, an adaptive immune response that might have evolved as a host defense against parasites and venoms. Yet it is apparent that mast cells are also activated through non-IgE receptors, the significance of which is just beginning to be understood. This includes the Mas-related G protein-coupled receptor X2, which might contribute to reactions to diverse antimicrobials and polybasic compounds, and the adhesion G protein-coupled receptor E2, variants of which are associated with familial vibratory urticaria and are activated by mechanical vibration. Similarly, mast cells have long been recognized as the main repository for histamine, heparin, and proteases. Recent evidence also points to new functions, modes of delivery, and mechanisms of action of mast cell proteases that add new dimensions to the roles of mast cells in human biology. In addition, exposure of mast cells to environmental cues can quantitatively and qualitatively modulate their responses and thus their effect on allergic inflammation. Illustrating this paradigm, we summarize a number of recent studies implicating the injury/tissue damage cytokine IL-33 as a modulator of allergen-induced mast cell responses. We also discuss the discovery of markers associated with transformed mast cells and new potential directions in suppressing mast cell activity.

Modulation of GPR133 (ADGRD1) signaling by its intracellular interaction partner extended synaptotagmin 1.

GPR133 (ADGRD1) is an adhesion G-protein-coupled receptor that signals through Gαs/cyclic AMP (cAMP) and is required for the growth of glioblastoma (GBM), an aggressive brain malignancy. The regulation of GPR133 signaling is incompletely understood. Here, we use proximity biotinylation proteomics to identify ESYT1, a Ca2+-dependent mediator of endoplasmic reticulum-plasma membrane bridge formation, as an intracellular interactor of GPR133. ESYT1 knockdown or knockout increases GPR133 signaling, while its overexpression has the opposite effect, without altering GPR133 levels in the plasma membrane. The GPR133-ESYT1 interaction requires the Ca2+-sensing C2C domain of ESYT1. Thapsigargin-mediated increases in cytosolic Ca2+ relieve signaling-suppressive effects of ESYT1 by promoting ESYT1-GPR133 dissociation. ESYT1 knockdown or knockout in GBM slows tumor growth, suggesting tumorigenic functions of ESYT1. Our findings demonstrate a mechanism for the modulation of GPR133 signaling by increased cytosolic Ca2+, which reduces the signaling-suppressive interaction between GPR133 and ESYT1 to raise cAMP levels.

The adhesion G protein-coupled receptor GPR56/ADGRG1 in cytotoxic lymphocytes.

GPR56/ADGRG1 is an adhesion G protein-coupled receptor connected to brain development, haematopoiesis, male fertility, and tumorigenesis. Nevertheless, expression of GPR56 is not restricted to developmental processes. Studies over the last years have demonstrated a marked presence of GPR56 in human cytotoxic NK and T cells. Expression of GPR56 in these cells is driven by the transcription factor HOBIT, corresponds with the production of cytolytic mediators and the presence of CX3 CR1 and CD57, indicates a state of terminal differentiation and cellular exhaustion, and disappears upon cellular activation. Functional studies indicate that GPR56 regulates cell migration and effector functions and thereby acts as an inhibitory immune checkpoint. We here discuss the current state of knowledge regarding GPR56 in cytotoxic lymphocytes.

The clinical relevance of the adhesion G protein-coupled receptor F5 for human diseases and cancers.

Among the numerous adhesion G protein-coupled receptors (GPCRs), adhesion G protein-coupled estrogen receptor F5 (ADGRF5) contains unique domains in the long N-terminal tail which can determine cell-cell and cell-matrix interaction as well as cell adhesion. Nevertheless, the biology of ADGRF5 is complex and still poorly explored. Accumulating evidence suggests that the ADGRF5 activity is fundamental in health and disease. For instance, ADGRF5 is essential in the proper function of lungs and kidney as well as the endocrine system, and its signification in vascularization and tumorigenesis has been demonstrated. The most recent studies have provided findings about the diagnostic potential of ADGRF5 in osteoporosis and cancers, and ongoing studies suggest other diseases as well. Here, we elaborate on the current state of knowledge about the ADGRF5 in the physiology and pathophysiology of human diseases and highlight its high potential as a novel target in various therapeutic areas.

Biased signalling is structurally encoded as an autoproteolysis event in adhesion G protein-coupled receptor Latrophilin-3/ADGRL3.

Adhesion G protein-coupled receptors (aGPCRs) possess a unique topology, including the presence of a GPCR proteolysis site (GPS), which, upon autoproteolysis, generates two functionally distinct fragments that remain non-covalently associated at the plasma membrane. A proposed activation mechanism for aGPCRs involves the exposure of a tethered agonist, which depends on cleavage at the GPS. However, this hypothesis has been challenged by the observation that non-cleavable aGPCRs exhibit constitutive activity, thus making the function of GPS cleavage widely enigmatic. In this study, we sought to elucidate the function of GPS-mediated cleavage through the study of G protein coupling with Latrophilin-3/ADGRL3, a prototypical aGPCR involved in synapse formation and function. Using BRET-based G protein biosensors, we reveal that an autoproteolysis-deficient mutant of ADGRL3 retains constitutive activity. Surprisingly, we uncover that cleavage deficiency leads to a signalling bias directed at potentiating the activity of select G proteins such as Gi2 and G12/13. These data unveil the underpinnings of biased signalling for aGPCRs defined by GPS autoproteolysis.