Differential contributions of G protein- or arrestin subtype-mediated signalling underlie urocortin 3-induced somatostatin secretion in pancreatic δ cells.

Background And Purpose: Pancreatic islets are modulated by cross-talk among different cell types and paracrine signalling plays important roles in maintaining glucose homeostasis. Urocortin 3 (UCN3) secreted by pancreatic β cells activates the CRF receptor (CRFR) and downstream pathways mediated by different G protein or arrestin subtypes in δ cells to cause somatostatin (SST) secretion, and constitutes an important feedback circuit for glucose homeostasis.

Experimental Approach: Here, we used Arrb1, Arrb2, Gs and Gq knockout mice, the G-shRNA-GFP lentivirus, as well as functional assays and pharmacological characterization to study how the coupling of G, G and β-arrestin1 to CRFR contributed to UCN3-induced SST secretion in pancreatic δ cells.

Deafness-Associated ADGRV1 Mutation Impairs USH2A Stability through Improper Phosphorylation of WHRN and WDSUB1 Recruitment.

The ankle-link complex (ALC) consists of USH2A, WHRN, PDZD7, and ADGRV1 and plays an important role in hair cell development. At present, its architectural organization and signaling role remain unclear. By establishing Adgrv1 Y6236fsX1 mutant mice as a model of the deafness-associated human Y6244fsX1 mutation, the authors show here that the Y6236fsX1 mutation disrupts the interaction between adhesion G protein-coupled receptor V subfamily member 1 (ADGRV1) and other ALC components, resulting in stereocilia disorganization and mechanoelectrical transduction (MET) deficits.

Endogenous Lipid-GPR120 Signaling Modulates Pancreatic Islet Homeostasis to Different Extents.

Long-chain fatty acids (LCFAs) are not only energy sources but also serve as signaling molecules. GPR120, an LCFA receptor, plays key roles in maintaining metabolic homeostasis. However, whether endogenous ligand-GPR120 circuits exist and how such circuits function in pancreatic islets are unclear.

Progesterone activates GPR126 to promote breast cancer development via the Gi pathway.

GPR126 is a member of the adhesion G protein-coupled receptors (aGPCRs) that is essential for the normal development of diverse tissues, and its mutations are implicated in various pathological processes. Here, through screening 34 steroid hormones and their derivatives for cAMP production, we found that progesterone (P4) and 17-hydroxyprogesterone (17OHP) could specifically activate GPR126 and trigger its downstream Gi signaling by binding to the ligand pocket in the seven-transmembrane domain of the C-terminal fragment of GPR126. A detailed mutagenesis screening according to a computational simulated structure model indicated that K1001ECL2 and F1012ECL2 are key residues that specifically recognize 17OHP but not progesterone.

Structures of the glucocorticoid-bound adhesion receptor GPR97-G complex.

Adhesion G-protein-coupled receptors (GPCRs) are a major family of GPCRs, but limited knowledge of their ligand regulation or structure is available. Here we report that glucocorticoid stress hormones activate adhesion G-protein-coupled receptor G3 (ADGRG3; also known as GPR97), a prototypical adhesion GPCR. The cryo-electron microscopy structures of GPR97-G complexes bound to the anti-inflammatory drug beclomethasone or the steroid hormone cortisol revealed that glucocorticoids bind to a pocket within the transmembrane domain.

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.

In vitro expansion of pancreatic islet clusters facilitated by hormones and chemicals.

Tissue regeneration, such as pancreatic islet tissue propagation in vitro, could serve as a promising strategy for diabetes therapy and personalised drug testing. However, such a strategy has not been realised yet. Propagation could be divided into two steps, in vitro expansion and repeated passaging.

Glucocorticoid modulatory element-binding protein 1 (GMEB1) interacts with the de-ubiquitinase USP40 to stabilize CFLAR and inhibit apoptosis in human non-small cell lung cancer cells.

Background: GMEB1 was originally identified via its interaction with GMEB2, which binds to the promoter region of the tyrosine aminotransferase (TAT) gene and modulates transactivation of the glucocorticoid receptor gene. In the cytosol, GMEB1 interacts with and inhibits CASP8, but the molecular mechanism is currently unknown.

Methods: Human non-small cell lung cancer cells and 293FT cells were used to investigate the function of GMEB1/USP40/CFLAR complex by WB, GST Pull-Down Assay, Immunoprecipitation, Immunofluorescence and Flow cytometry analysis.

The arginine methyltransferase PRMT5 and PRMT1 distinctly regulate the degradation of anti-apoptotic protein CFLAR in human lung cancer cells.

Background: CFLAR, also known as c-FLIP, is a critical anti-apoptotic protein that inhibits activation of caspase 8 in mammalian cells. Previous studies have shown that arginine 122 of CFLAR can be mono-methylated. However, the precise role of arginine methyltransferase of CFLAR remains unknown.