Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P01275 (glucagon)
 26,492 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Parathyroid hormone (PTH) is central to calcium homeostasis and bone maintenance in vertebrates, and as such it has been used for treating osteoporosis. It acts primarily by binding to its receptor, PTH1R, a member of the class B G protein-coupled receptor (GPCR) family that also includes receptors for glucagon, calcitonin, and other therapeutically important peptide hormones. Despite considerable interest and much research, determining the structure of the receptor-hormone complex has been hindered by difficulties in purifying the receptor and obtaining diffraction-quality crystals. Here, we present a method for expression and purification of the extracellular domain (ECD) of human PTH1R engineered as a maltose-binding protein (MBP) fusion that readily crystallizes. The 1.95-A structure of PTH bound to the MBP-PTH1R-ECD fusion reveals that PTH docks as an amphipathic helix into a central hydrophobic groove formed by a three-layer alpha-beta-betaalpha fold of the PTH1R ECD, resembling a hot dog in a bun. Conservation in the ECD scaffold and the helical structure of peptide hormones emphasizes this hot dog model as a general mechanism of hormone recognition common to class B GPCRs. Our findings reveal critical insights into PTH actions and provide a rational template for drug design that targets this hormone signaling pathway.
 ...
PMID:Molecular recognition of parathyroid hormone by its G protein-coupled receptor. 1837 60

Recently, we found that unsaturated long-chain fatty acids (such as alpha-linolenic acid) promote the secretion of glucagon-like peptide-1 (GLP-1) via G protein-coupled receptor GPR120, which is expressed predominantly in the colon. In order to ensure that the triglycerides or free fatty acids, such as alpha-linolenic acid, reach the distal intestinal tract effectively, we developed a Calshell technique. Following single treatment of Calshell perilla oil powder, the GLP-1 secretion level was significantly higher than following vehicle treatment, 120 min after treatment. Next, we examined the effects of long-term Calshell perilla oil powder treatment on GLP-1 secretion. Plasma GLP-1 level of Calshell perilla oil powder treatment was significantly higher than of vehicle treatment for 1, 14, 28 and 56 d. We thereby demonstrated for the first time the utility of Calshell oil powder treatment for effective and sustainable GLP-1 secretion. The Calshell technique is apparently useful as a drug delivery system, since Calshell unsaturated oil powder is protected from gastric acid, reaches enteroendocrine cells in the gastrointestinal tract, and then induces effective incretin secretion.
 ...
PMID:Administration of perilla oil coated with Calshell increases glucagon-like peptide secretion. 1845 39

Glucagon-like peptide-1 (GLP-1) is a gut-derived peptide secreted from intestinal L-cells and now considered as an ideal diabetic medicine. Recently, it was reported that the unsaturated fatty acid alpha-linoleic acid promotes the secretion of GLP-1 via a G protein-coupled receptor, GPR120. However, the effects of long-chain polyunsaturated fatty acids on the secretion of GLP-1 have not been examined in vivo. The aim of this study was to evaluate the effects of the long-chain polyunsaturated fatty acids docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) on blood glucose levels, plasma insulin, and GLP-1 concentrations. In addition, site-specific differences in these effects were determined using several intestinal segments: stomach, jejunum, and colon. After an intraperitoneal glucose administration (1.5 mg/g weight), each mouse was administered vehicle or an alpha-linoleic acid, DHA, EPA or EPA ester (EPA-E) solution to each intestinal segment. After an intraperitoneal glucose challenge, marked endogenous GLP-1 secretion, substantial insulin release and subsequent glucose reductions were observed in the intracolonic DHA and EPA treatment groups. In contrast, DHA and EPA did not increase GLP-1 secretion when given in the other segments. These data suggested that the colon-specific delivery of DHA, EPA, and possibly EPA-E would be a novel antidiabetic treatment by the stimulation of intrinsic GLP-1 secretion.
 ...
PMID:Usefulness of colon targeted DHA and EPA as novel diabetes medications that promote intrinsic GLP-1 secretion. 1880 28

Islet dysfunction - characterized by a combination of defective insulin secretion, inappropriately high glucagon secretion and reduced beta-cell mass - has a central role in the pathophysiology of type 2 diabetes. Several G protein-coupled receptors (GPCRs) expressed in islet beta-cells are known to be involved in the regulation of islet function, and therefore are potential therapeutic targets. This is evident from the recent success of glucagon-like peptide 1 (GLP1) mimetics and dipeptidyl peptidase 4 (DPP4) inhibitors, which promote activation of the GLP1 receptor to stimulate insulin secretion and inhibit glucagon secretion, and also have the potential to increase beta-cell mass. Other islet beta-cell GPCRs that are involved in the regulation of islet function include the glucose-dependent insulinotropic peptide (GIP) receptor, lipid GPCRs, pleiotropic peptide GPCRs and islet biogenic amine GPCRs. This Review summarizes islet GPCR expression, signalling and function, and highlights their potential as targets for the treatment of type 2 diabetes.
 ...
PMID:Islet G protein-coupled receptors as potential targets for treatment of type 2 diabetes. 1936 92

A number of highly promiscuous seven transmembrane (7TM) receptors have been cloned and characterized within the last few years. It is noteworthy that many of these receptors are activated broadly by amino acids, proteolytic degradation products, carbohydrates, or free fatty acids and are expressed in taste tissue, the gastrointestinal tract, endocrine glands, adipose tissue, and/or kidney. These receptors thus hold the potential to act as sensors of food intake, regulating, for example, release of incretin hormones from the gut, insulin/glucagon from the pancreas, and leptin from adipose tissue. The promiscuous tendency in ligand recognition of these receptors is in contrast to the typical specific interaction with one physiological agonist seen for most receptors, which challenges the classic "lock-and-key" concept. We here review the molecular mechanisms of nutrient sensing of the calcium-sensing receptor, the G protein-coupled receptor family C, group 6, subtype A (GPRC6A), and the taste1 receptor T1R1/T1R3, which are sensing L-alpha-amino acids, the carbohydrate-sensing T1R2/T1R3 receptor, the proteolytic degradation product sensor GPR93 (also termed GPR92), and the free fatty acid (FFA) sensing receptors FFA1, FFA2, FFA3, GPR84, and GPR120. The involvement of the individual receptors in sensing of food intake has been validated to different degrees because of limited availability of specific pharmacological tools and/or receptor knockout mice. However, as a group, the receptors represent potential drug targets, to treat, for example, type II diabetes by mimicking food intake by potent agonists or positive allosteric modulators. The ligand-receptor interactions of the promiscuous receptors of organic nutrients thus remain an interesting subject of emerging functional importance.
 ...
PMID:Molecular pharmacology of promiscuous seven transmembrane receptors sensing organic nutrients. 1948 46

Type 2 diabetes (T2D) and associated obesity have reached epidemic proportions, and there is an increasing need for orally effective agents that regulate glucose homeostasis with a concurrent reduction in body weight. GPR119, a class-A (rhodopsin-like) G protein-coupled receptor, expressed primarily in the human pancreas and gastrointestinal tract, has attracted considerable interest as a T2D drug target in the last three to five years. The activation of GPR119 increases the intracellular accumulation of cAMP, leading to enhanced glucose-dependent insulin secretion and increased levels of the incretin hormones GLP-1 (glucagon-like peptide 1) and GIP (glucose-dependent insulinotropic peptide). In rodent models, orally available GPR119-specific agonists have been shown to attenuate blood glucose levels with a simultaneous body weight loss. This review summarizes the research leading to the identification of GPR119 as a potential drug target for T2D and related metabolic disorders. In addition, an overview of the recent progress made in the discovery of orally active GPR119 agonists is provided.
 ...
PMID:GPR119 agonists: a promising new approach for the treatment of type 2 diabetes and related metabolic disorders. 1956 48

TGR5 is a G protein-coupled receptor expressed in brown adipose tissue and muscle, where its activation by bile acids triggers an increase in energy expenditure and attenuates diet-induced obesity. Using a combination of pharmacological and genetic gain- and loss-of-function studies in vivo, we show here that TGR5 signaling induces intestinal glucagon-like peptide-1 (GLP-1) release, leading to improved liver and pancreatic function and enhanced glucose tolerance in obese mice. In addition, we show that the induction of GLP-1 release in enteroendocrine cells by 6alpha-ethyl-23(S)-methyl-cholic acid (EMCA, INT-777), a specific TGR5 agonist, is linked to an increase of the intracellular ATP/ADP ratio and a subsequent rise in intracellular calcium mobilization. Altogether, these data show that the TGR5 signaling pathway is critical in regulating intestinal GLP-1 secretion in vivo, and suggest that pharmacological targeting of TGR5 may constitute a promising incretin-based strategy for the treatment of diabesity and associated metabolic disorders.
 ...
PMID:TGR5-mediated bile acid sensing controls glucose homeostasis. 2039 10

TGR5 is a G protein-coupled receptor expressed in brown adipose tissue and muscle, where its activation by bile acids triggers an increase in energy expenditure and attenuates diet-induced obesity. Using a combination of pharmacological and genetic gain- and loss-of-function studies invivo, we show here that TGR5 signaling induces intestinal glucagon-like peptide-1 (GLP-1) release, leading to improved liver and pancreatic function and enhanced glucose tolerance in obese mice. In addition, we show that the induction of GLP-1 release in enteroendocrine cells by 6alpha-ethyl-23(S)-methyl-cholic acid (EMCA, INT-777), a specific TGR5 agonist, is linked to an increase of the intracellular ATP/ADP ratio and a subsequent rise in intracellular calcium mobilization. Altogether, these data show that the TGR5 signaling pathway is critical in regulating intestinal GLP-1 secretion invivo, and suggest that pharmacological targeting of TGR5 may constitute a promising incretin-based strategy for the treatment of diabesity and associated metabolic disorders.
 ...
PMID:A new life for bile acids. 1972 93

During the last decades it has become clear that bile acids not only act as simple fat solubilizers, but additionally represent complex hormonal metabolic integrators. Bile acids activate both nuclear receptors (controlling transcription of genes involved in for example bile acid, cholesterol, and glucose metabolism) and the cell surface G protein-coupled receptor TGR5 (modulating energy expenditure in brown fat and muscle cells). It has been shown that TGR5 is expressed in enteroendocrine L cells, which secrete the potent glucose-lowering incretin hormone glucagon-like peptide-1 (GLP-1). Recently it was shown that bile acid-induced activation of TGR5 results in intestinal secretion of GLP-1 and that enhanced TGR5 signaling improves postprandial glucose tolerance in diet-induced obese mice. This Perspectives article presents these novel findings in the context of prior studies on nutrient-induced GLP-1 secretion and outlines the potential implications of bile acid-induced GLP-1 secretion in physiological, pathophysiological, and pharmacological perspectives.
 ...
PMID:Bile-induced secretion of glucagon-like peptide-1: pathophysiological implications in type 2 diabetes? 2042 39

The newly discovered G protein-coupled receptor GPR120 has recently been shown to stimulate secretion of the gut hormones glucagon-like peptide-1 and cholecystokinin upon binding of free fatty acids, thrusting it to the forefront of drug discovery efforts for treatment of type 2 diabetes as well as satiety and obesity. Although sequences for two alternative splice variants of the human GPR120 receptor have been reported, there have been no studies which directly compare the signaling of these isoforms. We have identified an additional 16 amino acid gap containing four phospho-labile serine/threonine residues which is localized to the third intracellular loop of the GPR120-long (GPR120-L) isoform. Based on this finding, we hypothesized that the agonist-stimulated phosphorylation profiles of this isoform would be distinct from that of the short isoform (GPR120-S). Using a clonal HEK293 cell model, we examined agonist-mediated phosphorylation of GPR120-S and GPR120-L with the omega-3 fatty acids alpha-linolenic acid (ALA) and docosahexaenoic acid (DHA). Our results show rapid phosphorylation of both isoforms following agonism by either ALA or DHA. Moreover, we show no significant difference in the degree or rate of phosphorylation of both isoforms upon agonism with either ALA or DHA, suggesting that the additional gap in the longer variant is not phosphorylated. Importantly, our results demonstrate that the shorter variant exhibits significantly more pronounced basal phosphorylation in the absence of agonist, suggesting that the additional gap in the long variant may contribute to masking of constitutive phosphorylation sites. These are the first results which demonstrate specific phosphorylation of GPR120 isoforms upon agonism by free fatty acids and the first which distinguish the phosphorylation profiles of the two GPR120 isoforms.
 ...
PMID:Agonism with the omega-3 fatty acids alpha-linolenic acid and docosahexaenoic acid mediates phosphorylation of both the short and long isoforms of the human GPR120 receptor. 2047 68


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>