Activity Of Pancreatic Beta-cells Research Articles

Gestational diabetes mellitus may predispose to metabolic dysfunction-associated steatotic liver disease

The development of type 2 diabetes mellitus is a major contributing factor to the worldwide health burden of metabolic dysfunction-associated steatotic liver disease (MASLD). Insulin resistance, subclinical inflammation, dyslipidemia, obesity, and hypertension are all factors in this reciprocal interaction that contribute to the development of MASLD, which includes hepatocellular carcinoma, advanced fibrosis/cirrhosis, and non-alcoholic steatohepatitis (NASH). A new risk factor for MASLD/NASH that affects the course of the disease independently throughout life is gestational diabetes mellitus (GDM). Women with a history of GDM had a higher chance of developing NASH, according to a recent study that used a large-scale database. Although the precise etiology is yet unknown, temporary disruption of pancreatic beta cell activity during pregnancy may set off systemic inflammation, affecting distant organs including the liver. Early screening and management strategies are crucial in mitigating MASLD progression and preventing adverse cardiovascular events in affected individuals.

An Overview of Differential miRNA Profile of Patients with Latent Autoimmune Diabetes in Adults (LADA)

Diabetes mellitus (DM) is a metabolic and chronic disease characterized by hyperglycemia developing with impaired pancreatic beta cell activity, decreased insulin secretion, icreased insulin resistance, and accordingly impaired carbohydrate, protein and lipid metabolism. DM is classified as type 1, type 2, gestational and other forms of diabetes according to the characteristic properties such as age of onset, insulin dependency, micro- and macrovascular complications. Latent autoimmune diabetes in adults (LADA) is an autoimmune diabetes that begins in adulthood without insulin dependency for glycemic control at least in the first six months after diagnosis. Owing to the common genetic, immunologic, and metabolic features LADA is misdiagnosed with type 1 or type 2 diabetes. Therefore, it is need a biomarkers that ease the diagnosis of LADA. MicroRNAs are small non-coding RNAs involved in biological processes and regulate the response of target tissues to insulin as well as insulin production, signaling and release, insulin resistance, and glucose homeostasis. Dysregulation in miRNA expression can lead to impairment of glucose metabolism. Circulating miRNA are associated with different types of diabetes and have a potential to discriminate them. So, we reviewed the miRNAs that gene expressions levels which change in LADA compared to type 1 and type 2 diabetes.

Vernonia amygdalina Del (Bitter leaf) a traditional anti-diabetic gold mine - Mini Review

Diabetes mellitus is a worldwide epidemic that has serious consequences for public health. This in-depth analysis of Vernonia amygdalina, or Bitter Leaf, aims to shed light on the plant's potential anti-diabetic properties by discussing its botanical description, chemical composition, traditional uses, and mechanisms of action, scientific findings, safety concerns, and implications for future study. Vernonia amygdalina, a plant native to various nations in Africa, has gained popularity as a possible treatment for diabetes. Bitter leaf's traditional function in reducing diabetes-related complications is also highlighted, and the review goes deeply into the plant's rich historical and cultural context. The possible anti-diabetic properties of Bitter leaf are discussed, along with the processes that may be at play. These include the effect on insulin sensitivity, glucose homeostasis, and pancreatic beta cell activity. Improving glycemic control and insulin resistance is only two of the positive effects seen in clinical trials and research investigations. There is also discussion of precautions to take, including details on how this treatment could interact with standard drugs. The review continues by stressing the need for more study to fill up the gaps in our understanding and pave the path for the deliberate application of Vernonia amygdalina as an adjunctive method of diabetes care. This analysis of Bitter leaf's diabetes-fighting properties adds to the increasing body of information around diabetes natural treatments, opening up new lines of inquiry and possible therapeutic applications in the field.

Silibinin as a promising treatment for diabetes: Insights into behavioral and metabolic changes in an animal model.

Diabetes mellitus is causing serious health problems in the chronic period. Silibinin is a flavonoid obtained from the milk thistle (Silybum marianum), which is among the herbal ethnopharmacological administrations. In studies with silibinin, it has been reported that it increases the activity of pancreatic beta cells and insulin sensitivity and has a hyperglycemia-reducing effect. However, behavioral parameters have not been evaluated together with insulin levels and liver function tests. Our aim in this study was to examine the effects of silibinin on insulin secretion, anxiety-like behaviors, and learning in a streptozotocin (STZ)-induced rat diabetes model. Wistar albino rats weighing 200-250 g were divided into 4 groups. Control: Saline solution, Diabetes: STZ 45 mg/kg, S 100: STZ 45 mg/kg + Silibinin 100 mg/kg, S 200: STZ 45 mg/kg + Silibinin 200 mg/kg. Administrations were continued for 21 days. On the 21st day, open field and elevated plus maze as unconditional anxiety tests; Barnes maze for learning and memory; and rotarod test for locomotor activity were conducted. Following behavioral tests, blood samples were taken under anesthesia. Blood glucose levels and ALT values were measured. Insulin levels were measured with an ELISA plate reader. Silibinin shortened the time to find the correct hole. Silibinin prevented the decrease in insulin due to STZ, exhibited a hyperglycemia-reducing effect and decreased the elevation of ALT.

Simvastatin, but not Pravastatin, Blocks L-Type Ca2+ Channels In Rat Islet -Cells, Inhibiting Glucose-Induced Cytosolic Ca2+ Signaling and Insulin Release

Patients with type 2 diabetes who have hypercholesterolemia frequently need to take HMG-CoA reductase inhibitors. A key factor in the pathophysiology of type 2 diabetes is altered pancreatic beta-cell activity, which results in a reduced ability of the pancreas to secrete insulin in response to glucose. The impact of HMG-CoA reductase inhibitors on -cell function must therefore be investigated. The regulation of -cell function is greatly influenced by the cytosolic Ca2+ concentration ([Ca2+]i). The current work looked at how HMG-CoA reductase inhibitors affected the [Ca2+]i signaling and insulin release that glucose-induced in rat islet -cells. Simvastatin, a lipophilic HMG-CoA reductase inhibitor, suppressed the initial phase increase and oscillation of [Ca2+]i caused by 8.3 mM glucose in single -cells at concentrations ranging from 0.1 to 3 g ml—1. The fewer Simvastatin-acid, a lipophilic inhibitor, decreased the first [Ca2+]i rise but was two orders of magnitude less effective. Pravastatin (100g ml—1), a hydrophilic inhibitor, has little impact on [Ca2+]. Simvastatin (0.3g ml–1) reduced glucose-induced insulin production from islets more effectively than simvastatin-acid (30g ml–1), whereas pravastatin (100g ml–1) had no effect. Simvastatin, but not pravastatin, showed a reversible blockage of the L-type Ca2+ channels in -cells in whole-cell patch clamp recordings. Simvastatin also prevented the opening of L-type Ca2+ channels, which is how L-arginine and HCl enhance [Ca2+] Conclusion: By blocking L-type Ca2+ channels in -cells, lipophilic HMG-CoA reductase inhibitors can prevent glucose-induced [Ca2+]i signaling and insulin secretion, and their inhibitory potencies are inversely correlated with their lipophilicities. Precaution must be takenWhen HMG-CoA reductase inhibitors are utilized in clinical settings, attention should be given to these findings, especially in type 2 diabetic patients.

KATP channel activity and slow oscillations in pancreatic beta cells are regulated by mitochondrial ATP production.

Pancreatic beta cells secrete insulin in response to plasma glucose. The ATP-sensitive potassium channel (KATP ) links glucose metabolism to islet electrical activity in these cells by responding to increased cytosolic [ATP]/[ADP]. It was recently proposed that pyruvate kinase (PK) in close proximity to beta cell KATP locally produces the ATP that inhibits KATP activity. This proposal was largely based on the observation that applying phosphoenolpyruvate (PEP) and ADP to the cytoplasmic side of excised inside-out patches inhibited KATP . To test the relative contributions of local vs. mitochondrial ATP production, we recorded KATP activity using mouse beta cells and INS-1 832/13 cells. In contrast to prior reports, we could not replicate inhibition of KATP activity by PEP+ADP. However, when the pH of the PEP solutions was not corrected for the addition of PEP, strong channel inhibition was observed as a result of the well-known action of protons to inhibit KATP . In cell-attached recordings, perifusing either a PK activator or an inhibitor had little or no effect on KATP channel closure by glucose, further suggesting that PK is not an important regulator of KATP . In contrast, addition of mitochondrial inhibitors robustly increased KATP activity. Finally, by measuring the [ATP]/[ADP] responses to imposed calcium oscillations in mouse beta cells, we found that oxidative phosphorylation could raise [ATP]/[ADP] even when ADP was at its nadir during the burst silent phase, in agreement with our mathematical model. These results indicate that ATP produced by mitochondrial oxidative phosphorylation is the primary controller of KATP in pancreatic beta cells. KEY POINTS: Phosphoenolpyruvate (PEP) plus adenosine diphosphate does not inhibit KATP activity in excised patches. PEP solutions only inhibit KATP activity if the pH is unbalanced. Modulating pyruvate kinase has minimal effects on KATP activity. Mitochondrial inhibition, in contrast, robustly potentiates KATP activity in cell-attached patches. Although the ADP level falls during the silent phase of calcium oscillations, mitochondria can still produce enough ATP via oxidative phosphorylation to close KATP . Mitochondrial oxidative phosphorylation is therefore the main source of the ATP that inhibits the KATP activity of pancreatic beta cells.

Fine-tuned photochromic sulfonylureas for optical control of beta cell Ca2+ fluxes.

We previously developed, synthesized and tested light-activated sulfonylureas for optical control of KATP channels and pancreatic beta cell activity in vitro and in vivo. Such technology relies on installation of azobenzene photoswitches onto the sulfonylurea backbone, affording light-dependent isomerization, alteration in ligand affinity for SUR1 and hence KATP channel conductance. Inspired by molecular dynamics simulations and to further improve photoswitching characteristics, we set out to develop a novel push-pull closed ring azobenzene unit, before installing this on the sulfonylurea glimepiride as a small molecule recipient. Three fine-tuned, light-activated sulfonylureas were synthesized, encompassing azetidine, pyrrolidine and piperidine closed rings. Azetidine-, pyrrolidine- and piperidine-based sulfonylureas all increased beta cell Ca2+ -spiking activity upon continuous blue light illumination, similarly to first generation JB253. Notably, the pyrrolidine-based sulfonylurea showed superior switch OFF performance to JB253. As such, third generation sulfonylureas afford more precise optical control over primary pancreatic beta cells, and showcase the potential of pyrrolidine-azobenzenes as chemical photoswitches across drug classes.

Effect of Tinospora cordifolia on gestational diabetes mellitus and its complications

ABSTRACT Ayurvedic system of medicine uses giloy or guduchi, also known as Tinospora cordifolia (TC), to treat diabetes and related diseases like hyperglycemia and hyperlipididemia. However, its usage in gestational diabetes mellitus (GDM) is not well studied. The primary objective of the study was to examine the effects of water extract of TC called satva, essential oil, and hydroalcoholic (HA) extract on GDM and its complications and to explore their mechanism of action using mice model. We used streptozotocin-induced diabetes in pregnant mice as murine model and tested TC preparations for anti-GDM activities. Blood glucose, insulin, litter size, and placental weight were assessed. ELISA method was used to measure plasma insulin level to compute homeostatic model assessment of insulin resistance (HOMA-IR), quantitative insulin sensitivity check index (QUICKI), and homeostatic model assessment for assessing beta cell function (HOMA-Beta) levels to estimate insulin resistance, insulin sensitivity, and beta cell function respectively. TC-treated groups had significantly higher serum insulin levels, QUICKI, average litter size, and lower placental weight (p < .001). TC oil and HA extract increased pancreatic beta cell activity according to the level of HOMA-Beta. TC lowered placenta weight and increased litter size significantly compared to control group. Our findings suggest that TC preparations preserve pancreatic beta cells, increase insulin production, decrease insulin resistance, and improve beta cell function, hence preventing GDM. TC preparations also reduced placental weight and increased litter size in mice. Based on these results, we recommend the clinical trial and testing of TC preparations for management of GDM and associated complications. Refer graphical abstract (Figure S1).

Tirzepatide: A Systematic Update.

Tirzepatide is a new molecule capable of controlling glucose blood levels by combining the dual agonism of Glucose-Dependent Insulinotropic Polypeptide (GIP) and Glucagon-Like Peptide-1 (GLP-1) receptors. GIP and GLP1 are incretin hormones: they are released in the intestine in response to nutrient intake and stimulate pancreatic beta cell activity secreting insulin. GIP and GLP1 also have other metabolic functions. GLP1, in particular, reduces food intake and delays gastric emptying. Moreover, Tirzepatide has been shown to improve blood pressure and to reduce Low-Density Lipoprotein (LDL) cholesterol and triglycerides. Tirzepatide efficacy and safety were assessed in a phase III SURPASS 1-5 clinical trial program. Recently, the Food and Drug Administration approved Tirzepatide subcutaneous injections as monotherapy or combination therapy, with diet and physical exercise, to achieve better glycemic blood levels in patients with diabetes. Other clinical trials are currently underway to evaluate its use in other diseases. The scientific interest toward this novel, first-in-class medication is rapidly increasing. In this comprehensive and systematic review, we summarize the main results of the clinical trials investigating Tirzepatide and the currently available meta-analyses, emphasizing novel insights into its adoption in clinical practice for diabetes and its future potential applications in cardiovascular medicine.

Physiological levels of adrenaline fail to stop pancreatic beta cell activity at unphysiologically high glucose levels.

Adrenaline inhibits insulin secretion from pancreatic beta cells to allow an organism to cover immediate energy needs by unlocking internal nutrient reserves. The stimulation of α2-adrenergic receptors on the plasma membrane of beta cells reduces their excitability and insulin secretion mostly through diminished cAMP production and downstream desensitization of late step(s) of exocytotic machinery to cytosolic Ca2+ concentration ([Ca2+]c). In most studies unphysiologically high adrenaline concentrations have been used to evaluate the role of adrenergic stimulation in pancreatic endocrine cells. Here we report the effect of physiological adrenaline levels on [Ca2+]c dynamics in beta cell collectives in mice pancreatic tissue slice preparation. We used confocal microscopy with a high spatial and temporal resolution to evaluate glucose-stimulated [Ca2+]c events and their sensitivity to adrenaline. We investigated glucose concentrations from 8-20 mM to assess the concentration of adrenaline that completely abolishes [Ca2+]c events. We show that 8 mM glucose stimulation of beta cell collectives is readily inhibited by the concentration of adrenaline available under physiological conditions, and that sequent stimulation with 12 mM glucose or forskolin in high nM range overrides this inhibition. Accordingly, 12 mM glucose stimulation required at least an order of magnitude higher adrenaline concentration above the physiological level to inhibit the activity. To conclude, higher glucose concentrations stimulate beta cell activity in a non-linear manner and beyond levels that could be inhibited with physiologically available plasma adrenaline concentration.

Butyrate inhibits IL-1β-induced inflammatory gene expression by suppression of NF-κB activity in pancreatic beta cells

Cytokine-induced beta cell dysfunction is a hallmark of type 2 diabetes (T2D). Chronic exposure of beta cells to inflammatory cytokines affects gene expression and impairs insulin secretion. Thus, identification of anti-inflammatory factors that preserve beta cell function represents an opportunity to prevent or treat T2D. Butyrate is a gut microbial metabolite with anti-inflammatory properties for which we recently showed a role in preventing interleukin-1β (IL-1β)-induced beta cell dysfunction, but how prevention is accomplished is unclear. Here, we investigated the mechanisms by which butyrate exerts anti-inflammatory activity in beta cells. We exposed mouse islets and INS-1E cells to a low dose of IL-1β and/or butyrate and measured expression of inflammatory genes and nitric oxide (NO) production. Additionally, we explored the molecular mechanisms underlying butyrate activity by dissecting the activation of the nuclear factor-κB (NF-κB) pathway. We found that butyrate suppressed IL-1β-induced expression of inflammatory genes, such as Nos2, Cxcl1, and Ptgs2, and reduced NO production. Butyrate did not inhibit IκBα degradation nor NF-κB p65 nuclear translocation. Furthermore, butyrate did not affect binding of NF-κB p65 to target sequences in synthetic DNA but inhibited NF-κB p65 binding and RNA polymerase II recruitment to inflammatory gene promoters in the context of native DNA. We found this was concurrent with increased acetylation of NF-κB p65 and histone H4, suggesting butyrate affects NF-κB activity via inhibition of histone deacetylases. Together, our results show butyrate inhibits IL-1β-induced inflammatory gene expression and NO production through suppression of NF-κB activation and thereby possibly preserves beta cell function.

Early Effects of Metabolic Syndrome on ATP-Sensitive Potassium Channels from Rat Pancreatic Beta Cells.

Metabolic syndrome (MS) is a cluster of metabolic signs that increases the risk of developing type 2 two diabetes mellitus and cardiovascular diseases. MS leads to pancreatic beta cell exhaustion and decreased insulin secretion through unknown mechanisms in a time-dependent manner. ATP-sensitive potassium channels (KATP channels), common targets of anti-diabetic drugs, participate in the glucose-stimulated insulin secretion, coupling the metabolic status and electrical activity of pancreatic beta cells. We investigated the early effects of MS on the conductance, ATP and glybenclamide sensitivity of the KATP channels. We used Wistar rats fed with a high-sucrose diet (HSD) for 8 weeks as a MS model. In excised membrane patches, control and HSD channels showed similar unitary conductance and ATP sensitivity pancreatic beta cells in their KATP channels. In contrast, MS produced variability in the sensitivity to glybenclamide of KATP channels. We observed two subpopulations of pancreatic beta cells, one with similar (Gly1) and one with increased (Gly2) glybenclamide sensitivity compared to the control group. This study shows that the early effects of MS produced by consuming high-sugar beverages can affect the pharmacological properties of KATP channels to one of the drugs used for diabetes treatment.

Histology of hematoxylin–eosin and immunohistochemical diabetes rat pancreas after giving combination of moringa leaves (Moringa oleifera) and clove flower (Syzygium aromaticum) extracts

The purpose of this study was to determine the regeneration activity of pancreatic beta cells by a combination of the ethanol extracts of Moringa leaves and Clove flower. These extracts prepared by maceration with ethanol as solvent . This is an experimental laboratory research by using post test only group design . The subject of this research is 40 white male rats of Wistar strain ( Rattus norvegicus ) and were conditioned DM by streptozotozine-nicotinamide induction . The rats randomly divided into 8 groups , and each group consisted of 5 rats . Combination dose of Moringa leaves and Clove flowers extracts used are 150 : 40 mg / kg body weight of mice , 100 : 80 mg / kg body weight of mice and 50 : 120 mg / kg body weight of mice . The rats were sacrificed and the pancreas taken to be made preparations histopathology , staining and observation tissues with HE and IHC methods. The results showed that the staining and observation tissues of heart with HE method acquired the positive control group , the single test group and the combination group were showing the islet on the Langerhans island of the pancreas is bigger than in the negative control group. The morphology of the island of Langerhans increasingly large indicates increasing the regeneration of the cells of the islet beta pancreas; whereas the method of IHC acquired the negative control group seen lack of display intensity of positive reaction Ag &amp; Ab beta cells with are marked with brown cells . In the positive control group , the single test group and the combination group , seen a positive reaction of Ag &amp; Ab insulin-producing beta cells characterized by brown cells and insulin expression dominating pancreatic island of Langerhans.

NMDA receptor inhibition increases, synchronizes, and stabilizes the collective pancreatic beta cell activity: Insights through multilayer network analysis.

NMDA receptors promote repolarization in pancreatic beta cells and thereby reduce glucose-stimulated insulin secretion. Therefore, NMDA receptors are a potential therapeutic target for diabetes. While the mechanism of NMDA receptor inhibition in beta cells is rather well understood at the molecular level, its possible effects on the collective cellular activity have not been addressed to date, even though proper insulin secretion patterns result from well-synchronized beta cell behavior. The latter is enabled by strong intercellular connectivity, which governs propagating calcium waves across the islets and makes the heterogeneous beta cell population work in synchrony. Since a disrupted collective activity is an important and possibly early contributor to impaired insulin secretion and glucose intolerance, it is of utmost importance to understand possible effects of NMDA receptor inhibition on beta cell functional connectivity. To address this issue, we combined confocal functional multicellular calcium imaging in mouse tissue slices with network science approaches. Our results revealed that NMDA receptor inhibition increases, synchronizes, and stabilizes beta cell activity without affecting the velocity or size of calcium waves. To explore intercellular interactions more precisely, we made use of the multilayer network formalism by regarding each calcium wave as an individual network layer, with weighted directed connections portraying the intercellular propagation. NMDA receptor inhibition stabilized both the role of wave initiators and the course of waves. The findings obtained with the experimental antagonist of NMDA receptors, MK-801, were additionally validated with dextrorphan, the active metabolite of the approved drug dextromethorphan, as well as with experiments on NMDA receptor KO mice. In sum, our results provide additional and new evidence for a possible role of NMDA receptor inhibition in treatment of type 2 diabetes and introduce the multilayer network paradigm as a general strategy to examine effects of drugs on connectivity in multicellular systems.

Biomarkers: An Important Tool for Diagnosing and Treating Diabetes Mellitus

Diabetes mellitus is a group of metabolic disease caused by an abnormal increase in blood glucose levels due to abnormal activity of pancreatic beta cells. Elevated blood glucose levels causes a variety of cell damage, including endothelial cells, neurons, renal cells, keratinocytes, and fibroblasts. Chronic diabetes mellitus causes several diabetic manifestations such as diabetic neuropathy, diabetic nephropathy, diabetic myopathy, and diabetic dermopathy. There are many causes and risks of diabetes mellitus, including type 1 diabetes caused by bacterial infections, chemical poisoning with food, and self-resistance; Type 2 diabetes is caused by obesity, weight gain, prediabetes and family history, and type 3 is caused by Cushing's syndrome. Diabetes mellitus treatment has encountered a few progressions in the previous decades with the revelation of explicit prescient prognostic biomarkers that make conceivable the use of individualized treatments. Various hypoglycemic oral and parenteral dosage formulations are used to treat diabetes mellitus, but insulin therapy is one of the most effective treatments for type 1 and type 2 diabetes and its complications. Various conventional diagnosing and treating methods of diabetes mellitus are available but there are limitations of resistance and, accuracy. For that reason now a day’s various biomarkers like Autoantibodies, C-reactive protein (CRP), Fibrinogen, Interleukin-1 receptor antagonist (IL-1RA), Plasminogen activator inhibitor (PAI-1), etc. are used for diagnosis; Adiponectin, microRNA, Acylcarnitine, Haemoglobin A1c, etc. are used for treatment, and 1,5-anhydroglucitol are used for both diagnosis and treatment of diabetes mellitus. In this review, we discussed the functions, application and limitations of diabetes biomarkers in their use as diagnostic and treatment. These biomarkers are of paramount importance in the assessment and diagnosis process, leading to better care and protection of patients. Due to its various advantages, biomarkers are considered as an innovative tool in the advancement of diagnosis and treatment of diabetes mellitus.&#x0D;

The Potency of Senggani (Melastoma malabathricum L) Leaves in Repair of Pancreatic Beta Cells for Diabetes Mellitus Patients: A Narrative Review

Diabetes mellitus is often caused by damage to pancreatic beta cells which play a role in secreting insulin in the body. Damage to pancreatic beta cells causes the body to lack insulin. Dipeptidyl peptidase-4 (DPP-4) is a peptidase enzyme complex located on the surface of the cell membrane. Inhibition of the DPP4 enzyme will increase blood GLP-1 levels and induce regeneration of pancreatic beta cells. Senggani leaf (Melastoma malabathricum) boiled water is believed by the people of the Ciamis area to be used as a diabetes medicine. There have been many studies and reviews related to Senggani (Melastoma malabathricum) and its potential. This review focuses on the discussion of Senggani as an antidiabetic by analyzing the reduction in glucose levels and the repair ability of pancreatic beta cells. The results of the literature study that show that senggani leaves have the ability to reduce blood glucose levels and repair activity of pancreatic beta cells through the DPP-4 enzyme inhibition mechanism supported by molecular docking simulation data. There are 12 active compounds that have a binding site similarity above 50% with the comparison compound vildagliptin. Rutin is the best active compound which has a 100% similarity of the binding site. Based on in vivo research and toxicity analysis on the admetsar database, senggani leaf extract and active compounds of senggani leaves have low toxicity, making it safe to be used as antidiabetic herbal preparations.

2195-P: Identification of the Regulatory Mechanism of mTORC1 Signaling Activity in Pancreatic Beta Cells in GCN2 Knockout Mice

Background and Objective: A single-nucleotide polymorphism (SNP) analysis of Japanese type 2 diabetes (T2DM) patients has revealed a significant correlation between a SNP of GCN2 and T2DM. We have demonstrated that islets isolated from GCN2 knockout (GCN2-/-) mice fed a high-fat diet (HFD) exhibited decreased expression of ATF4, a downstream molecule of GCN2, and pancreatic β-cell failure via hyperactivation of mTORC1 signaling. However, the mechanism of activated mTORC1 signaling has remained unclear. Therefore, our objective is to identify the regulatory mechanism of mTORC1 signaling activity in pancreatic β-cells of GCN2-/- mice fed an HFD. Methods: We analyzed using islets isolated from GCN2-/- mice and wild type mice fed an HFD, and pancreatic β-cell lines. Results: In pancreatic islets isolated from GCN2-/- mice fed an HFD, the phosphorylation of TSC2 was enhanced. Therefore, we speculated that there would be a pathway which regulated mTORC1 signaling via TSC2. It has been reported that TSC2 phosphorylation is regulated by its association with 14-3-3. We started to identify the molecule X downstream of GCN2, which involved in the regulation of mTORC1 signaling activity by competitively inhibiting the binding of TSC2 and 14-3-3. We carried out a proteome analysis to explore the molecules whose binding with 14-3-3 varied depending on the presence or the absence of GCN2. As a result, five molecules were listed, and Asparaginase was identified as the candidate of the molecule X. We revealed that Asparaginase was abundantly expressed in pancreatic islets following heart in mice tissues. In glucose loaded MIN6 cells and amino acid deficient MIN6 cells, the expression of Asparaginase was increased. Furthermore, the increased expression of Asparaginase by amino acid deficiency was decreased by ATF4 knocking down. Conclusion: It was suggested that Asparaginase was involved in the regulation of mTORC1 signaling activity downstream of GCN2-ATF4 pathway. Disclosure M. Kudo: None. S. Asahara: Research Support; Spouse/Partner; AstraZeneca. A. Kanno: None. Y. Kido: Research Support; Self; AstraZeneca.

2143-P: GLP-1 Conjugation Enhances the Activity of Antisense Oligonucleotides Targeting Islet Amyloid Polypeptide (IAPP) or Kelch-Like ECH Associated Protein 1 (Keap1) in Isolated Pancreatic Islets

The incidence of type 2 diabetes (T2D) is increasing rapidly and is currently one of the 21st century’s major challenges to human health. While T2D has a complex etiology, beta cell dysfunction is widely regarded as a key contributor to T2D disease progression. Antisense oligonucleotides (ASOs) have been shown to provide substantial therapeutic benefit for numerous unmet medical needs. However, unconjugated ASOs have shown minimal activity in pancreatic beta cells, limiting their use as therapeutics in these cells. It has recently been shown that conjugation of glucagon like peptide 1 receptor (GLP-1R) ligands (GLP-1R-L) to ASOs led to significant, substantial increases of ASO activity in the pancreatic islet beta cell, making them a viable therapeutic option for treatment of beta cell dysfunction.1 Two factors that contribute to beta cell dysfunction are IAPP and oxidative stress. A key inhibitor of the intracellular anti-oxidative response is Keap1. We treated isolated islets with parent or GLP-1R-L conjugated ASOs targeting either Keap1 or IAPP. At the highest dose, the parent ASOs reduced their respective islet target mRNAs by up to 20%, while the GLP-1 conjugated ASOs reduced target mRNA by 85%-95%. Furthermore, the GLP-1R-L conjugated Keap1 ASO treatment increased mRNA expression of the anti-oxidative response gene NAD(P)H quinone dehydrogenase 1 (Nqo1) by 390% when compared to PBS controls. Systemic treatment of C57BL/6 mice with the GLP-1R-L conjugated IAPP ASO reduced islet IAPP mRNA by 79% ± 3.7% when compared to saline treated animals. These data suggest that GLP-1R-L conjugated ASOs show exciting potential as a therapeutic platform for the treatment of beta cell dysfunction. Disclosure W. Fu: None. R. Lee: Employee; Self; Ionis Pharmaceuticals, Inc. E.C. Pirie: Employee; Self; Ionis Pharmaceuticals, Inc. T. Prakash: Employee; Self; Ionis Pharmaceuticals, Inc. S. Murray: Employee; Self; Ionis Pharmaceuticals, Inc. A.F. Powers: Employee; Self; Ionis Pharmaceuticals, Inc. Stock/Shareholder; Self; Ionis Pharmaceuticals, Inc. R.M. Crooke: Employee; Self; Ionis Pharmaceuticals, Inc. Employee; Spouse/Partner; Ionis Pharmaceuticals, Inc.

347-LB: MEA Technology as an Easy Electrophysiological Approach for Noninvasive Recordings of Intact Murine and Human Islets

Increase of blood glucose concentration leads to glucose-induced electrical activity of pancreatic beta-cells followed by insulin secretion. Electrical activity appears in glucose concentration-dependent oscillations easily recorded by microelectrode arrays (MEA). In comparison to other electrophysiological techniques MEAs can record non-invasively from intact islets and can be used for long term studies to investigate chronic effects of drugs. Murine islets or islets isolated from human biopsies were used for recordings. Electrical activity was quantified as fraction of plateau Phase (FOPP) or number of single spike activity. Islets were placed via suction or cultivated on MEAs. The glucose concentration response curve recorded with murine islets plotted as FOPP revealed a half-maximal activity of 12 ± 2 mM which is in line with traditional methods like e.g., with intracellular electrodes. Glucose-induced activity of cultured islets remains stable over a month. Application of well-known substances (like e.g., diazoxide, tolbutamide) matched regular results. Human islets displayed typical glucose-induced activity (10 mM). Validation studies showed the existence of functional KATP channels and TTX reduced spike activity from 1047 ± 314 to 199 ± 90 spikes/5min after the application of 300 nM TTX. The washout led to an increased spike activity of 779 ± 301 spikes/minutes. The glucose concentration response curve revealed an EC50 value of 8 ± 3 mM glucose. The glucose responsiveness recorded with the MEA Technology is in line with other reports showing that the EC50 value of human beta-cells (∼ 6 mM) is lower than in mouse beta-cells. MEA Technology allows medium throughput recordings from up to 40 intact islets simultaneously. While previous electrophysiological attempts failed MEAs offer large scale research in both academics and industry. The principle of function is not limited to rodent but is also applicable to human or stem cell derived islets of Langerhans. Disclosure S. Schönecker: None. M. Oza: Employee; Self; Multichannel Systems, Gmbh. U. Kraushaar: None.

Fibroblast growth factor receptor 5 (FGFR5) is a co-receptor for FGFR1 that is up-regulated in beta-cells by cytokine-induced inflammation

Fibroblast growth factor receptor-1 (FGFR1) activity at the plasma membrane is tightly controlled by the availability of co-receptors and competing receptor isoforms. We have previously shown that FGFR1 activity in pancreatic beta-cells modulates a wide range of processes, including lipid metabolism, insulin processing, and cell survival. More recently, we have revealed that co-expression of FGFR5, a receptor isoform that lacks a tyrosine-kinase domain, influences FGFR1 responses. We therefore hypothesized that FGFR5 is a co-receptor to FGFR1 that modulates responses to ligands by forming a receptor heterocomplex with FGFR1. We first show here increased FGFR5 expression in the pancreatic islets of nonobese diabetic (NOD) mice and also in mouse and human islets treated with proinflammatory cytokines. Using siRNA knockdown, we further report that FGFR5 and FGFR1 expression improves beta-cell survival. Co-immunoprecipitation and quantitative live-cell imaging to measure the molecular interaction between FGFR5 and FGFR1 revealed that FGFR5 forms a mixture of ligand-independent homodimers (∼25%) and homotrimers (∼75%) at the plasma membrane. Interestingly, co-expressed FGFR5 and FGFR1 formed heterocomplexes with a 2:1 ratio and subsequently responded to FGF2 by forming FGFR5/FGFR1 signaling complexes with a 4:2 ratio. Taken together, our findings identify FGFR5 as a co-receptor that is up-regulated by inflammation and promotes FGFR1-induced survival, insights that reveal a potential target for intervention during beta-cell pathogenesis.