GLP1R boosts survival, migration and invasion of endometrial cancer cells and protects against ferroptotic cell death.

BACKGROUND: Despite the strong evidence concerning carcinogenic roles of glucagon-like peptide 1 receptor (GLP1R), the role of this gene in endometrial cancer (EC) remains elusive. This study investigated the properties of GLP1R on EC in vitro. METHODS: The expression of GLP1R in EC was detected by RT-qPCR, immunohistochemistry, and western blotting. Cell viability, cell cycle, apoptosis, migration, invasion and ferroptosis were assessed through CCK-8, flow cytometry, wound healing, transwell, DCFH-DA and western blotting, respectively. RESULTS: We found that GLP1R was up-regulated in EC than normal specimens. It had the highest expression in AN3CA cells. Cell viability, migration and invasion were significantly reduced, while cell cycle arrest and apoptosis were induced following GLP1R knockdown. The malignant biological behaviours of AN3CA cells were investigated when treated with exendin-4 (GLP1R agonist). Moreover, GLP1R lowered intracellular ROS level and expression of SLC7A11, and FTH1, but mitigated GPX4 expression in AN3CA cells. CONCLUSION: In a word, GLP1R was up-regulated in EC and its up-regulation facilitated the proliferative and metastatic potentials, and protected cells from ferroptosis, thereby accelerating EC progression. These data emphasised the potency of GLP1R as a therapeutic agent against EC.

Endometrial cancer (EC) is the second most common form of gynaecologic malignancy, with over 189,000 new cases and about 45,000 deaths worldwide per annum. The effects of glucagon-like peptide 1 receptor (GLP1R) in cancers such as colon and pancreatic cancers have been uncovered. However, whether GLP1R affects EC progression especially ferroptosis process remains elusive. In this study, up-regulation of GLP1R promotes the proliferative and metastatic potentials of EC cells, and protects EC cells from ferroptosis. The opposite results are observed in GLP1R knocking-down. Our study found that GLP1R may exert an oncogene function in EC cells, which can affect proliferative, migrated as well as invasive capacities of EC cells. Moreover, it protected EC cells from ferroptosis. Thus, our results expanded the understanding of the function of GLP1R protein and offered insights into the targeted treatment strategies against EC.

[Effect and mechanism of Zexie Decoction in promoting white adipose tissue browning/brown adipose tissue activation based on GLP-1R/cAMP/PKA/CREB pathway].

This study investigated the mechanism of Zexie Decoction(ZXD) in promoting white adipose tissue browning/brown adipose tissue activation based on the GLP-1R/cAMP/PKA/CREB pathway. A hyperlipidemia model was induced by a western diet(WD) in mice, and the mice were divided into a control group, a model group(WD), and low-, medium-, and high-dose ZXD groups. An adipogenesis model was induced in 3T3-L1 cells in vitro, and with forskolin(FSK) used as a positive control, low-, medium-, and high-dose ZXD groups were set up. Immunohistochemistry and immunofluorescence results showed that compared with the WD group, ZXD promoted the expression of UCP1 in white and brown adipose tissues, and also upregulated UCP1, CPT1ß, PPARα, and other genes in the cells. Western blot analysis showed a dose-dependent increase in the protein expression of PGC-1α, UCP1, and PPARα with ZXD treatment, indicating that ZXD could promote the white adipose tissue browning/brown adipose tissue activation. Hematoxylin-eosin(HE) staining results showed that after ZXD treatment, white and brown adipocytes were significantly reduced in size, and the mRNA expression of ATGL, HSL, MGL, and PLIN1 was significantly upregulated as compared with the results in the WD group. Oil red O staining and biochemical assays indicated that ZXD improved lipid accumulation and promoted lipolysis. Immunohistochemistry and immunofluorescence staining for p-CREB revealed that ZXD reversed the decreased expression of p-CREB caused by WD. In vitro intervention with ZXD increased the protein expression of CREB, p-CREB, and p-PKA substrate, and increased the mRNA level of CREB. ELISA detected an increase in intracellular cAMP concentration with ZXD treatment. Molecular docking analysis showed that multiple active components in Alismatis Rhizoma and Atractylodis Macrocephalae Rhizoma could form stable hydrogen bond interactions with GLP-1R. In conclusion, ZXD promotes white adipose tissue browning/brown adipose tissue activation both in vivo and in vitro, and its mechanism of action may be related to the GLP-1R/cAMP/PKA/CREB pathway.

Schisandrin B, a potential GLP-1R agonist, exerts anti-diabetic effects by stimulating insulin secretion.

Diabetes mellitus is a metabolic disease that is characterized by elevated blood sugar. Although glucagon-like peptide-1 receptor agonists (GLP-1RA) lower blood glucose in a glucose-dependent manner, most of them are macromolecule polypeptides. Macromolecular peptides are relatively expensive and inconvenient compared with small molecules. Therefore, this study sought to identify the small molecules binding to GLP-1R via cell membrane chromatography (CMC), confirm their agonistic activity, and further study its beneficial effects in a mouse model of type 2 diabetes mellitus (T2DM) induced by a combination of high-fat diet and streptozotocin. We used CMC, calcium imaging and molecular docking techniques to screen and identify the potential small molecule Schisandrin B (Sch B), which exhibits a strong binding effect to GLP-1R, from the small molecule library of traditional Chinese medicine. Through in-vitro experiments, we found that Sch B stimulated insulin secretion in ß-TC-6 cells, while GLP-1R antagonist Exendin9-39, adenylate cyclase inhibitor SQ22536, and protein kinase A (PKA) inhibitor H89 could significantly inhibit the insulin secretion induced by Sch B. In vivo, Sch B significantly improved fasting blood glucose levels, intraperitoneal glucose tolerance test damage, and the status of pancreatic tissue damage, and reduced serum insulin levels, total cholesterol, triglyceride and low density lipoprotein in T2DM mice. These results indicate that Sch B alleviates T2DM by promoting insulin release through the GLP-1R/cAMP/PKA signaling pathway, suggesting that Sch B may be a potential GLP-1RA, which is expected to provide a new therapeutic strategy for the prevention and treatment of T2DM.

Tanycytes control hypothalamic liraglutide uptake and its anti-obesity actions.

Liraglutide, an anti-diabetic drug and agonist of the glucagon-like peptide one receptor (GLP1R), has recently been approved to treat obesity in individuals with or without type 2 diabetes. Despite its extensive metabolic benefits, the mechanism and site of action of liraglutide remain unclear. Here, we demonstrate that liraglutide is shuttled to target cells in the mouse hypothalamus by specialized ependymoglial cells called tanycytes, bypassing the blood-brain barrier. Selectively silencing GLP1R in tanycytes or inhibiting tanycytic transcytosis by botulinum neurotoxin expression not only hampers liraglutide transport into the brain and its activation of target hypothalamic neurons, but also blocks its anti-obesity effects on food intake, body weight and fat mass, and fatty acid oxidation. Collectively, these striking data indicate that the liraglutide-induced activation of hypothalamic neurons and its downstream metabolic effects are mediated by its tanycytic transport into the mediobasal hypothalamus, strengthening the notion of tanycytes as key regulators of metabolic homeostasis.

Emerging agents for the treatment and prevention of stroke: progress in clinical trials.

INTRODUCTION: Recent years have witnessed unprecedented progress in stroke care, but unmet needs persist regarding the efficacy of acute treatment and secondary prevention. Novel approaches are being tested to enhance the efficacy of thrombolysis or provide neuroprotection in non-thrombolized patients. AREAS COVERED: The current review highlights pharmaceutical agents under evaluation in clinical trials concerning the acute, subacute, and chronic phase post-stroke. We examine the evidence in favor of tenecteplase as an alternative thrombolytic drug to alteplase, nerinetide as a promising neuroprotective agent, and glibenclamide for reducing edema in malignant hemispheric infarction. We discuss the use of ticagrelor and the promising novel category of factor XI inhibitors in the subacute phase after stroke. We offer our insights on combined rivaroxaban and antiplatelet therapy, PCSK-9 inhibitors, and other non-statin hypolipidemic agents, as well as novel antidiabetic agents that have been shown to reduce cardiovascular events in the long-term. EXPERT OPINION: Current approaches in stroke treatment and stroke prevention have already transformed stroke care from a linear one-for-all treatment paradigm to a more individualized approach that targets specific patient subgroups with novel pharmaceutical agents. This tendency enriches the therapeutic armamentarium with novel agents developed for specific stroke subgroups. ABBREVIATIONS: IVT: intravenous thrombolysis; RCTs: randomized-controlled clinical trials; TNK: Tenecteplase; COVID-19: Coronavirus 2019 Disease; EXTEND-IA TNK: The Tenecteplase versus Alteplase Before Endovascular Therapy for Ischemic Stroke trial; AIS: acute ischemic stroke; NNT: number needed to treat; MT: mechanical thrombectomy; sICH: symptomatic intracranial hemorrhage; mRS: modified Rankin Scale; AHA/ASA: American Heart Association/American Stroke Association; ESO: European Stroke Organization; NA-1: Nerinetide; ENACT: Evaluating Neuroprotection in Aneurysm Coiling Therapy; CTA: CT angiography; TIA: transient ischemic attack; CHANCE: Clopidogrel in High-risk patients with Acute Non-disabling Cerebrovascular Events; LOF: loss-of-function; PRINCE: Platelet Reactivity in Acute Nondisabling Cerebrovascular Events; THALES: Acute Stroke or Transient Ischemic Attack Treated with Ticagrelor and ASA [acetylsalicylic acid] for Prevention of Stroke and Death; CHANCE-2: Clopidogrel With Aspirin in High-risk Patients With Acute Non-disabling Cerebrovascular Events II; FXI: Factor XI; PACIFIC-STROKE: Program of Anticoagulation via Inhibition of FXIa by the Oral Compound BAY 2433334-NonCardioembolic Stroke study; COMPASS: Cardiovascular Outcomes for People Using Anticoagulation Strategies; CANTOS-ICAD: Combination Antithrombotic Treatment for Prevention of Recurrent Ischemic Stroke in Intracranial Atherosclerotic Disease; SAMMPRIS: Stenting and Aggressive Medical Therapy for Preventing Recurrent Stroke in Intracranial Stenosis; WASID: Warfarin-Aspirin Symptomatic Intracranial Disease; SPARCL: Stroke Prevention by Aggressive Reduction in Cholesterol Levels; LDL-C: low-density lipoprotein cholesterol; TST: Treat Stroke to Target; IMPROVE-IT: Improved Reduction of Outcomes: Vytorin Efficacy International Trial; PCSK9: proprotein convertase subtilisin-kexin type 9; FOURIER: Further Cardiovascular Outcomes Research with PCSK9 Inhibition in Subjects with Elevated Risk; CLEAR: Cholesterol Lowering via Bempedoic acid, an ACL-inhibiting Regimen; REDUCE-IT: Reduction of Cardiovascular Events With EPA Intervention Trial; STRENGTH: Outcomes Study to Assess STatin Residual Risk Reduction With EpaNova in HiGh CV Risk PatienTs With Hypertriglyceridemia; ACCORD: Action to Control Cardiovascular Risk in Diabetes; ADVANCE: Action in Diabetes and Vascular Disease: Preterax and Diamicron Modified Release Controlled Evaluation; VADT: Veterans Affairs Diabetes Trial; GLP-1R: Glucagon-like peptide-1 receptor; SGLT2: sodium-glucose cotransporter 2; CONVINCE: COlchicine for preventioN of Vascular Inflammation in Non-CardioEmbolic stroke; PROBE: Prospective Randomized Open-label Blinded Endpoint assessment.

The GLP-1 receptor herbal agonist morroniside attenuates neuropathic pain via spinal microglial expression of IL-10 and ß-endorphin.

OBJECTIVES: To assess the protective effect of the glucagon-like peptide-1 receptor (GLP-1R) agonist morroniside against neuropathic pain and its downstream mechanisms of activating microglial GLP-1R/interleukin-10 (IL-10)/ß-endorphin antinociceptive pathway. METHODS: Spinal nerve ligation-induced neuropathic pain rats were intrathecally injected with morroniside, with mechanical paw withdrawal threshold being assessed. The expression of spinal and cultured microglia IL-10 and ß-endorphin were detected with qRT-PCR. KEY FINDINGS: Morroniside alleviated mechanical allodynia in neuropathic rats, which was blocked by inhibiting or depleting microglia. In addition, neutralizing spinal IL-10 or ß-endorphin with specialized antibodies or blocking the µ-opioid receptor was able to fully reverse the morroniside-induced mechanical antiallodynia. Morroniside treatment stimulated the gene expression of IL-10 and ß-endorphin in the spinal lumbar enlargements of neuropathic rats as well as in primary cultured microglia. Furthermore, pretreatment with the IL-10 antibody blocked morroniside-stimulated ß-endorphin expression in the spinal cords of neuropathic rats and cultured primary microglia, whereas the ß-endorphin antibody failed to affect morroniside-stimulated gene expression of IL-10. CONCLUSIONS: These results reveal that morroniside produces therapeutic effects in neuropathy through spinal microglial expression of IL-10 and subsequent ß-endorphin after activation of GLP-1R.

Puerarin ameliorates hyperglycemia in HFD diabetic mice by promoting ß-cell neogenesis via GLP-1R signaling activation.

BACKGROUND: Diabetes is characterized by ß-cell loss and dysfunction. A strategy for diabetes treatment is to promote new ß-cell formation. Puerarin is an isoflavone from the root of Pueraria lobata (Willd.) Ohwi. Our previous study demonstrated puerarin could ameliorate hyperglycemia in diabetic mice. However, related mechanisms and potential roles of puerarin in ß-cell neogenesis have not been elucidated. PURPOSE: The present study aims to investigate whether anti-diabetic effect of puerarin is dependent on promoting ß-cell neogenesis via GLP-1R signaling activation. METHODS: A high-fat diet (HFD) induced diabetic mouse model was applied to investigate effects of puerarin in vivo, exendin-4 (GLP-1R agonist) and metformin were used as positive controls. Moreover, related mechanisms and GLP-1R downstream signal transduction were explored in isolated cultured mouse pancreatic ductal cells. RESULTS: Puerarin improved glucose homeostasis in HFD diabetic mice significantly. Markers of new ß-cell formation (insulin, PDX1 and Ngn3) were observed in pancreatic ducts of HFD mice treated by puerarin. Of note, efficacy of puerarin in vivo was suppressed by GLP-1R antagonist exendin9-39, but enhanced by exendin-4 respectively. In cultured mouse pancreatic ductal cells, puerarin induced expressions of insulin and PDX1, upregulated GLP-1R expression and activated ß-catenin and STAT3 subsequently. Expressions of insulin and PDX1 in ductal cells could be blocked by exendin9-39, or ß-catenin inhibitor ICG001, or JAK2 inhibitor AG490. CONCLUSION: These data clarified puerarin ameliorated hyperglycemia of HFD mice via a novel mechanism involved promoting ß-cell neogenesis. Our finding highlights the potential value of puerarin developing as an anti-diabetic agent.

Long-Lasting Effects of GSPE on Ileal GLP-1R Gene Expression Are Associated with a Hypomethylation of the GLP-1R Promoter in Female Wistar Rats.

Flavonoids have been shown to modulate GLP-1 in obesity. GLP-1 induces some of its effects through the intestinal GLP-1 receptor (GLP-1R), though no data exist on how flavonoids affect this receptor. Here, we examine how a dose of grape seed proanthocyanidin extract (GSPE) with anti-obesity activity affects intestinal GLP-1R and analyze whether epigenetics play a role in the long-lasting effects of GSPE. We found that 10-day GSPE administration prior to the cafeteria diet upregulated GLP-1R mRNA in the ileum 17 weeks after the GSPE treatment. This was associated with a hypomethylation of the GLP-1R promoter near the region where the SP1 transcription factor binds. In the colon, the cafeteria diet upregulated GLP-1R without showing any GSPE effect. In conclusion, we have identified long-lasting GSPE effects on GLP-1R gene expression in the ileum that are partly mediated by hypomethylation at the gene promoter and may affect the SP1 binding factor.

Screening GLP-1 Receptor Ligands from Natural Products in Herbs through High-Content Technique.

AIM AND OBJECTIVE: Screening of active components from a natural product, especially from a crude extract, is a great challenge. To avoid potential activity interference of the N-terminus modification in the most common constructs based on GCPRs labeled with GFP technology, a Cterminus tGFP-labeled hGLP-1 receptor containing recombinant cell line hGLP-1R-tGFP was constructed and tried to be used in the screening of natural products from Chinese herb. MATERIALS AND METHODS: The GLP1 receptor gene was amplified and the inserts pCMV6-AC-tGFP and tGFP were fused at the C-terminus of GLP1 receptor to construct a recombinant plasmid. The recombinant was transfected into U2OS cell and selected with antibiotics and flow cytometry. The constructed cell line was named as hGLP-1R-tGFP cell line. The expression levels of GLP-1R-tGFP protein were confirmed by western-blot. The fluorescence imaging of re-distribution from diffusing to aggregate spots inside the cells was quantitated and analyzed by High Content Screening (HCS) assay. Meanwhile, the specificity, stability and C-terminus function of hGLP-1R-tGFP cell line were characterized. In order to allow the recombinant cell line of hGLP-1R-tGFP to be suitable in highcontent system of Arrayscan-infinity-700 in screening mode, several conditions have also been optimized. In the end, a total of 100 crude extract samples provided by the Yunnan Institute of Materia Medica have been screened with this method. RESULTS: Upon the activation of GLP-1 receptors by Exendin 4, fluorescent patches appeared on the cell membrane and subsequently internalized to form fluorescent aggregates inside the cells under fluorescent microscopy examination. The agonistic activity, sensitivity and specificity of the formation of fluorescent aggregate spot in hGLP-1R-tGFP cells have been confirmed by the activation of GLP-1R using the GLP-1analogues. The agonistic effects of GLP-1 analogues are blocked by a GLP-1R antagonist, Exendin9-39. The downstream of GLP-1 pathway, the activation of adenylate cyclase and the raising of cellular cAMP levels, remained intact in these tGFP modified C-terminus GLP-1 receptor cells. Meanwhile, a total of 100 crude extract samples from Chinese herbs have been screened by this method to find new active ingredients. CONCLUSION: Combined with High Content Screening image and data automatic acquisition processing, a new screening assay based on a recombinant U2OS cell line which GFP labeled at the C terminus of GLP1 receptor has been developed. GLP-1R agonist activity in extracts of Astragalus propinquus and Panax notoginseng from Chinese herbs has been determined by this method.

Exendin-4 decreases ghrelin levels through mTOR signaling.

Exendin-4 (EX-4), a long-acting glucagon-like peptide-1 receptor (GLP-1R) agonist, regulates feeding behavior through its ability to inhibit gastric emptying. Ghrelin, a gastric hormone, provides a hunger signal to the central nervous system to stimulate appetite. Here, we report that EX-4 suppresses ghrelin production through the mTORC1-dependent mechanism. Central administration of EX-4 reduces gastric, hypothalamic and plasma ghrelin in both C57BL/6J mice and diet induced obese mice. These changes were associated with a significant increase in mTORC1 activity. Both GLP-1 and EX-4 suppressed the expression and secretion of ghrelin in cultured mHypoE-42 cells, a hypothalamic cell line. These effects were associated with significant changes in mTOR signaling. Inhibition of mTORC1 activity by mTOR siRNA or rapamycin abolished the suppression of ghrelin production induced by GLP-1 and EX-4 in mHypoE-42 cells. Our results identify mTORC1 as a critical signaling pathway for the downregulation of ghrelin induced by activation of GLP-1R.

Peptidic exenatide and herbal catalpol mediate neuroprotection via the hippocampal GLP-1 receptor/ß-endorphin pathway.

Both peptidic agonist exenatide and herbal agonist catalpol of the glucagon-like peptide-1 receptor (GLP-1R) are neuroprotective. We have previously shown that activation of spinal GLP-1Rs expresses ß-endorphin in microglia to produce antinociception. The aim of this study was to explore whether exenatide and catalpol exert neuroprotection via activation of the hippocampal GLP-1R/ß-endorphin pathway. The rat middle cerebral artery occlusion model was employed, and the GLP-1R immunofluorescence staining and ß-endorphin measurement were assayed in the hippocampus and primary cultures of microglia, neurons and astrocytes. The immunoreactivity of GLP-1Rs on microglia in the hippocampus was upregulated after ischemia reperfusion. Intracerebroventricular (i.c.v.) injection of exenatide and catalpol produced neuroprotection in the rat transient ischemia/reperfusion model, reflected by a marked reduction in brain infarction size and a mild recovery in neurobehavioral deficits. In addition, i.c.v. injection of exenatide and catalpol significantly stimulated ß-endorphin expression in the hippocampus and cultured primary microglia (but not primary neurons or astrocytes). Furthermore, exenatide and catalpol neuroprotection was completely blocked by i.c.v. injection of the GLP-1R orthosteric antagonist exendin (9-39), specific ß-endorphin antiserum, and selective opioid receptor antagonist naloxone. Our results indicate, for the first time, that the neuroprotective effects of catalpol and exenatide are GLP-1R-specific, and that these effects are mediated by ß-endorphin expression probably in hippocampal microglia. We postulate that in contrast to the peripheral tissue, where the activation of GLP-1Rs in pancreas islet ß-cells causes secretion of insulin to perform glucoregulation, it leads to ß-endorphin expression in microglial cells to produce neuroprotection and analgesia in the central nervous system.

Differences in acute anorectic effects of long-acting GLP-1 receptor agonists in rats.

Long-acting glucagon-like peptide-1 receptor (GLP-1R) agonists have both glucose- and weight-lowering effects. The brain is poised to mediate both of these actions since GLP-1Rs are present in key areas known to control weight and glucose. Although some research has been performed on the effects of exendin-4 in the brain, little data exists on the central effects of liraglutide, a long-acting GLP-1R agonist with much closer structural homology to native GLP-1. In lean, Long-Evans rats, we found that direct intra-third cerebroventricular (i3vt) administration of 0.26 nmol liraglutide caused a 50% reduction in food intake. However, exendin-4 produced the same reduction in food intake with 10-fold greater potency (0.02 nmol). These data are supported by similar c-Fos immunoreactivity in the hypothalamic paraventricular nuclei by exendin-4 as compared to liraglutide despite differing doses. The anorectic effects of both drugs were blocked with i3vt pre-treatment of a GLP-1R competitive antagonist, exendin(9-39), indicating that both drugs required the GLP-1R for their effects. Exendin-4, and not liraglutide, caused hyperglycemia when given i3vt prior to an oral glucose tolerance test, although liraglutide did not lower glucose. Thus, these data show that GLP-1R agonists have differing anorectic potencies in the CNS, which may account for some of their clinical differences. Additionally, we show here that the glucose lowering properties of acute administration of GLP-1R agonists are not accounted for by their central effects.

GLP-1 receptor signaling is not required for reduced body weight after RYGB in rodents.

Exaggerated GLP-1 and PYY secretion is thought to be a major mechanism in the reduced food intake and body weight after Roux-en-Y gastric bypass surgery. Here, we use complementary pharmacological and genetic loss-of-function approaches to test the role of increased signaling by these gut hormones in high-fat diet-induced obese rodents. Chronic brain infusion of a supramaximal dose of the selective GLP-1 receptor antagonist exendin-9-39 into the lateral cerebral ventricle significantly increased food intake and body weight in both RYGB and sham-operated rats, suggesting that, while contributing to the physiological control of food intake and body weight, central GLP-1 receptor signaling tone is not the critical mechanism uniquely responsible for the body weight-lowering effects of RYGB. Central infusion of the selective Y2R-antagonist BIIE0246 had no effect in either group, suggesting that it is not critical for the effects of RYGB on body weight under the conditions tested. In a recently established mouse model of RYGB that closely mimics surgery and weight loss dynamics in humans, obese GLP-1R-deficient mice lost the same amount of body weight and fat mass and maintained similarly lower body weight compared with wild-type mice. Together, the results surprisingly provide no support for important individual roles of either gut hormone in the specific mechanisms by which RYGB rats settle at a lower body weight. It is likely that the beneficial effects of bariatric surgeries are expressed through complex mechanisms that require combination approaches for their identification.

Lixisenatide for the treatment of type 2 diabetes.

Lixisenatide (trade name Lyxumia®), a short-acting glucagon-like peptide 1 receptor (GLP-1R) agonist, was approved for the treatment of type 2 diabetes by the European Medicines Agency in early 2013. In preclinical investigations, acceptable toxicity and carcinogenicity profiles were demonstrated, as well as pancreatic beta cell-preserving actions and favorable effects on glycemic control. Following subcutaneous administration in humans, lixisenatide displays linear pharmacokinetics and an absorption-dependent elimination half-life of 2-3 hours. In clinical trials of up to 1 year duration in patients with type 2 diabetes, treatment with lixisenatide alone and in combination with insulin and various oral antidiabetics conferred significant reductions in HbA1c, fasting and postprandial plasma glucose. In direct comparison with the other GLP-1R agonists on the market (exenatide and liraglutide), lixisenatide appears to be less efficient, or at best non-inferior in terms of reducing HbA1c, fasting plasma glucose and body weight. Nevertheless, lixisenatide confers fewer adverse events than the other currently marketed GLP-1R agonists, while exhibiting a clinically valuable effect on postprandial hyperglycemia.

A novel glucagon-like peptide 1 peptide identified from Ophisaurus harti.

Glucagon-like peptide 1 receptor (GLP1R) is a promising target for the treatment of type 2 diabetes. Because of the short half-life of endogenous GLP1 peptide, other GLP1R agonists are considered to be appealing therapeutic candidates. A high-throughput assay has been established to screen for GLP1R agonists in a 60 000-well natural product compound library fractionated from 670 different herbs/materials widely used in traditional Chinese medicines (TCMs). The screening is based on primary screen of GLP1R⁺ reporter gene assay with the counter screen in GLP1R⁻ cell line. An active fraction, A089-147, was identified from the screening. Fraction A089-147 was isolated from dried Ophisaurus harti, and the fact that its GLP1R agonist activity was sensitive to trypsin treatment indicates its peptidic nature. The active ingredient of A089-147 was later identified as O. harti GLP1 through transcriptome analysis. Chemically synthesized O. harti GLP1 showed GLP1R agonist activity and sensitivity to dipeptidase IV digestion. This study illustrated a comprehensive screening strategy to identify novel GLP1R agonists from TCMs libraries and at the same time underlined the difficulty of identifying a non-peptidic GLP1R agonist. The novel O. harti GLP1 peptide yielded from this study confirmed broader application of TCMs libraries in active peptide identification.