Glucose Homeostasis In Diabetic Mice Research Articles

Acinar to β-like cell conversion through inhibition of focal adhesion kinase

Insufficient functional β-cell mass causes diabetes; however, an effective cell replacement therapy for curing diabetes is currently not available. Reprogramming of acinar cells toward functional insulin-producing cells would offer an abundant and autologous source of insulin-producing cells. Our lineage tracing studies along with transcriptomic characterization demonstrate that treatment of adult mice with a small molecule that specifically inhibits kinase activity of focal adhesion kinase results in trans-differentiation of a subset of peri-islet acinar cells into insulin producing β-like cells. The acinar-derived insulin-producing cells infiltrate the pre-existing endocrine islets, partially restore β-cell mass, and significantly improve glucose homeostasis in diabetic mice. These findings provide evidence that inhibition of the kinase activity of focal adhesion kinase can convert acinar cells into insulin-producing cells and could offer a promising strategy for treating diabetes.

Engineered poly(A)-surrogates for translational regulation and therapeutic biocomputation in mammalian cells

Here, we present a gene regulation strategy enabling programmable control over eukaryotic translational initiation. By excising the natural poly-adenylation (poly-A) signal of target genes and replacing it with a synthetic control region harboring RNA-binding protein (RBP)-specific aptamers, cap-dependent translation is rendered exclusively dependent on synthetic translation initiation factors (STIFs) containing different RBPs engineered to conditionally associate with different eIF4F-binding proteins (eIFBPs). This modular design framework facilitates the engineering of various gene switches and intracellular sensors responding to many user-defined trigger signals of interest, demonstrating tightly controlled, rapid and reversible regulation of transgene expression in mammalian cells as well as compatibility with various clinically applicable delivery routes of in vivo gene therapy. Therapeutic efficacy was demonstrated in two animal models. To exemplify disease treatments that require on-demand drug secretion, we show that a custom-designed gene switch triggered by the FDA-approved drug grazoprevir can effectively control insulin expression and restore glucose homeostasis in diabetic mice. For diseases that require instantaneous sense-and-response treatment programs, we create highly specific sensors for various subcellularly (mis)localized protein markers (such as cancer-related fusion proteins) and show that translation-based protein sensors can be used either alone or in combination with other cell-state classification strategies to create therapeutic biocomputers driving self-sufficient elimination of tumor cells in mice. This design strategy demonstrates unprecedented flexibility for translational regulation and could form the basis for a novel class of programmable gene therapies in vivo.

Berberine ameliorates glucocorticoid-induced hyperglycemia: an in vitro and in vivo study.

Berberine (BBR), a bioactive compound isolated from Coptidis Rhizoma, possesses diverse pharmacological activities including anti-bacterial, anti-inflammatory, antitumor, hypolipidemic, and anti-diabetic. However, its role as an anti-diabetic agent in animal models of dexamethasone (Dex)-induced diabetes remains unknown. Studies have shown that natural compounds including aloe, caper, cinnamon, cocoa, green and black tea, and turmeric can be used for treating Type 2 diabetes mellitus (DM). Compared to conventional drugs, natural compounds have less side effects and are easily available. Herein, we studied the anti-diabetic effects of BBR in a mice model of Dex-induced diabetes. HepG2 cell line was used for glucose release and glycogen synthesis studies. Cell proliferation was measured by methylthiotetrazole (MTT) assay. For animal studies, mice were treated with Dex (2mg/kg, i.m.) for 30days and effect of BBR at the doses 100, 200, and 500mg/kg (p.o.) was analyzed. Glucose, insulin, and pyruvate tests were performed for evaluating the development of the diabetic model. Echo MRI was performed to assess the fat mass. Further, to elucidate the mechanism of action of BBR, mRNA expression of genes regulating gluconeogenesis, glucose uptake, and glycolysis was analyzed. In vitro BBR had no impact on cell viability up to a concentration of 50μM. Moreover, BBR suppressed the hepatic glucose release and improved glucose tolerance in HepG2 cells. In vivo, BBR improved glucose homeostasis in diabetic mice as evidenced by enhanced glucose clearance, increased glycolysis, elevated glucose uptake, and decreased gluconeogenesis. Further, Dex treatment increased the total fat mass in mice, which was ameliorated by BBR treatment. BBR improves glucose tolerance by increasing glucose clearance, inhibiting hepatic glucose release, and decreasing obesity. Thus, BBR may become a potential therapeutic agent for treating glucocorticoid-induced diabetes and obesity in the future.

PAQR9 regulates glucose homeostasis in diabetic mice and modulates insulin secretion in β cells in vitro under stress conditions

Progesterone and adipoQ receptor 9 (PAQR9) is an endoplasmic reticulum (ER)-localized membrane protein that is involved in protein quality control of ER by interacting with BAG6. One of the physiological functions of PAQR9 is regulation of fasting-induced ketogenesis and fatty acid oxidation in the liver via modulating protein degradation of PPARα. However, it is currently unknown whether or not PAQR9 impacts glucose homeostasis. We addressed this question using a Paqr9-deleted mouse model in which type 1 diabetes was induced by streptozotocin injection and type 2 diabetes was induced by high-fat diet (HFD) with streptozotocin injection. Paqr9 deletion improved hyperglycemia and glucose tolerance in both of the diabetic mouse models. In the pancreatic islets, Paqr9 deletion reduced apoptosis of β cells in type 2 diabetic mice. Paqr9 deletion also reduced HFD-induced hepatic steatosis and adiposity of white adipose tissue. In Min6 cells, overexpression of DUF3538 domain of BAG6 to block the interaction of PAQR9 with BAG6 was able to enhance glucose-stimulated insulin secretion upon treatment with inflammatory factors or thapsigargin, an ER stress inducer. Thapsigargin-induced ER stress markers were also reduced by overexpression of DUF3538 domain. Collectively, these results indicate that PAQR9 has a modulatory role in glucose homeostasis, associated with regulation on insulin secretion of β cells in vitro under stress conditions.

1774-P: Verapamil Prevents Decline of IGF-1 in Subjects with T1D

We have previously found that the calcium channel blocker and anti-hypertensive, verapamil, promotes functional beta cell mass and improves glucose homeostasis in diabetic mice and in humans with recent-onset type 1 diabetes (T1D). Surprisingly, we also discovered that verapamil reversed the T1D-associated elevation in T-follicular-helper cell markers in peripheral blood monocytes, suggesting that it also has immunomodulatory effects. Now, a global proteomics analysis using liquid chromatography-tandem mass spectrometry (LC-MS/MS) of serum samples from T1D subjects at baseline and after 1 year of receiving verapamil or placebo identified insulin-like growth factor 1 (IGF-1) as one of the top proteins with significantly changed abundance over time. Specifically, IGF-1 abundance decreased during year 1 after diagnosis in subjects with T1D receiving placebo, which is consistent with the lower IGF-1 levels reported previously in individuals with T1D as compared to age- and sex-matched healthy subjects. Interestingly, this decline was blunted in subjects receiving verapamil. To further confirm the LC-MS/MS results, we also measured patient serum levels of IGF-1 by ELISA. The results were very much in alignment and again revealed significantly decreased IGF-1 levels in the placebo group a year after diagnosis, but no such effect in the verapamil treatment group, suggesting that verapamil prevents the decline of IGF-1 in subjects with T1D. Of note, IGF-1, which is primarily produced in liver, acts on many tissues, including pancreatic islets promoting pathways involved in cell growth, differentiation and glucose metabolism. In beta cells, IGF-1 has also been shown to control apoptosis. Thus, our results reveal yet another previously unappreciated pathway affected by verapamil that may contribute to the beneficial effects observed with this treatment in the context of T1D. Disclosure G.Xu: None. J.Chen: None. B.Lu: None. W.Qian: None. A.Shalev: Other Relationship; TIXiMED. Funding National Institutes of Health (R01DK078752, U01DK120379)

GP73 blockade alleviates abnormal glucose homeostasis in diabetic mice.

Golgi protein 73 (GP73), also called Golgi membrane protein 1 (GOLM1), is a resident Golgi type II transmembrane protein and is considered as a serum marker for the detection of a variety of cancers. A recent work revealed the role of the secreted GP73 in stimulating liver glucose production and systemic glucose homeostasis. Since exaggerated hepatic glucose production plays a key role in the pathogenesis of type 1 diabetes mellitus (T1DM) and type 2 diabetes mellitus (T2DM), GP73 may thus represent a potential therapeutic target for treating diabetic patients with pathologically elevated levels. Here, in this study, we found that the circulating GP73 levels were significantly elevated in T2DM and positively correlated with hemoglobin A1c. Notably, the aberrantly upregulated GP73 levels were indispensable for the enhanced protein kinase A signaling pathway associated with diabetes. In diet-induced obese mouse model, GP73 siRNA primarily targeting liver tissue was potently effective in alleviating abnormal glucose metabolism. Ablation of GP73 from whole animals also exerted a profound glucose-lowering effect. Importantly, neutralizing circulating GP73 improved glucose metabolism in streptozotocin (STZ) and high-fat diet/STZ-induced diabetic mice. We thus concluded that GP73 was a feasible therapeutic target for the treatment of diabetes.

The TBK1/IKKε inhibitor amlexanox improves dyslipidemia and prevents atherosclerosis.

Cardiovascular diseases, especially atherosclerosis and its complications, are a leading cause of death. Inhibition of the noncanonical IκB kinases TANK-binding kinase 1 and IKKε with amlexanox restores insulin sensitivity and glucose homeostasis in diabetic mice and human patients. Here we report that amlexanox improves diet-induced hypertriglyceridemia and hypercholesterolemia in Western diet–fed (WD-fed) Ldlr–/– mice and protects against atherogenesis. Amlexanox ameliorated dyslipidemia, inflammation, and vascular dysfunction through synergistic actions that involve upregulation of bile acid synthesis to increase cholesterol excretion. Transcriptomic profiling demonstrated an elevated expression of key bile acid synthesis genes. Furthermore, we found that amlexanox attenuated monocytosis, eosinophilia, and vascular dysfunction during WD-induced atherosclerosis. These findings demonstrate the potential of amlexanox as a therapy for hypercholesterolemia and atherosclerosis.

Intermittent protein restriction protects islet β cells and improves glucose homeostasis in diabetic mice

Diabetes is caused by the interplay between genetics and environmental factors, tightly linked to lifestyle and dietary patterns. In this study, we explored the effectiveness of intermittent protein restriction (IPR) in diabetes control. IPR drastically reduced hyperglycemia in both streptozotocin-treated and leptin receptor-deficient db/db mouse models. IPR improved the number, proliferation, and function of β cells in pancreatic islets. IPR reduced glucose production in the liver and elevated insulin signaling in the skeletal muscle. IPR elevated serum level of FGF21, and deletion of the Fgf21 gene in the liver abrogated the hypoglycemic effect of IPR without affecting β cells. IPR caused less lipid accumulation and damage in the liver than that caused by continuous protein restriction in streptozotocin-treated mice. Single-cell RNA sequencing using mouse islets revealed that IPR reversed diabetes-associated β cell reduction and immune cell accumulation. As IPR is not based on calorie restriction and is highly effective in glycemic control and β cell protection, it has promising translational potential in the future.

GLUT4-overexpressing engineered muscle constructs as a therapeutic platform to normalize glycemia in diabetic mice.

Skeletal muscle insulin resistance is a main defect in type 2 diabetes (T2D), which is associated with impaired function and content of glucose transporter type 4 (GLUT4). GLUT4 overexpression in skeletal muscle tissue can improve glucose homeostasis. Therefore, we created an engineered muscle construct (EMC) composed of GLUT4-overexpressing (OEG4) cells. The ability of the engineered implants to reduce fasting glucose levels was tested in diet-induced obesity mice. Decrease and stabilization of basal glucose levels were apparent up to 4 months after implantation. Analysis of the retrieved constructs showed elevated expression of myokines and proteins related to metabolic processes. In addition, we validated the efficiency of OEG4-EMCs in insulin-resistant mice. Following high glucose load administration, mice showed improved glucose tolerance. Our data indicate that OEG4-EMC implant is an efficient mode for restoring insulin sensitivity and improving glucose homeostasis in diabetic mice. Such procedure is a potential innovative modality for T2D therapy.

Paired box 6 programs essential exocytotic genes in the regulation of glucose-stimulated insulin secretion and glucose homeostasis.

The paired box 6 (PAX6) transcription factor is crucial for normal pancreatic islet development and function. Heterozygous mutations of PAX6 are associated with impaired insulin secretion and early-onset diabetes mellitus in humans. However, the molecular mechanism of PAX6 in controlling insulin secretion in human beta cells and its pathophysiological role in type 2 diabetes (T2D) remain ambiguous. We investigated the molecular pathway of PAX6 in the regulation of insulin secretion and the potential therapeutic value of PAX6 in T2D by using human pancreatic beta cell line EndoC-βH1, the db/db mouse model, and primary human pancreatic islets. Through loss- and gain-of-function approaches, we uncovered a mechanism by which PAX6 modulates glucose-stimulated insulin secretion (GSIS) through a cAMP response element-binding protein (CREB)/Munc18-1/2 pathway. Moreover, under diabetic conditions, beta cells and pancreatic islets displayed dampened PAX6/CREB/Munc18-1/2 pathway activity and impaired GSIS, which were reversed by PAX6 replenishment. Adeno-associated virus-mediated PAX6 overexpression in db/db mouse pancreatic beta cells led to a sustained amelioration of glycemic perturbation in vivo but did not affect insulin resistance. Our study highlights the pathophysiological role of PAX6 in T2D-associated beta cell dysfunction in humans and suggests the potential of PAX6 gene transfer in preserving and restoring beta cell function.

Ectopic Leptin Production by Intraocular Pancreatic Islet Organoids Ameliorates the Metabolic Phenotype of ob/ob Mice.

The pancreatic islets of Langerhans consist of endocrine cells that secrete peptide hormones into the blood circulation in response to metabolic stimuli. When transplanted into the anterior chamber of the eye (ACE), pancreatic islets engraft and maintain morphological features of native islets as well as islet-specific vascularization and innervation patterns. In sufficient amounts, intraocular islets are able to maintain glucose homeostasis in diabetic mice. Islet organoids (pseudo-islets), which are formed by self-reassembly of islet cells following disaggregation and genetic manipulation, behave similarly to native islets. Here, we tested the hypothesis that genetically engineered intraocular islet organoids can serve as production sites for leptin. To test this hypothesis, we chose the leptin-deficient ob/ob mouse as a model system, which becomes severely obese, hyperinsulinemic, hyperglycemic, and insulin resistant. We generated a Tet-OFF-based beta-cell-specific adenoviral expression construct for mouse leptin, which allowed efficient transduction of native beta-cells, optical monitoring of leptin expression by co-expressed fluorescent proteins, and the possibility to switch-off leptin expression by treatment with doxycycline. Intraocular transplantation of islet organoids formed from transduced islet cells, which lack functional leptin receptors, to ob/ob mice allowed optical monitoring of leptin expression and ameliorated their metabolic phenotype by improving bodyweight, glucose tolerance, serum insulin, and C-peptide levels.

1248-P: Histone Deacetylase Inhibition Improves Store-Operated Calcium Entry and Glucose-Stimulated Insulin Secretion in Cytokine-Stressed Pancreatic ß-Cells

Store-operated calcium entry (SOCE) functions to refill endoplasmic reticulum (ER) Ca2+ stores in response to ER Ca2+ depletion through gating of plasmalemmal Orai channels by the ER Ca2+ sensor STIM1. Dysfunctional β cell SOCE has been observed in response to cytokine-mediated stress, whereas select histone deacetylase (HDAC) inhibitors are able to protect against cytokine-mediated β cell death and have been shown to improve glucose homeostasis in diabetic mice. Here, we tested the relationship between HDAC inhibition and SOCE in the pancreatic β cell. To this end, we investigated the effects of the HDAC inhibitor sodium butyrate (NaB) on Ca2+ signaling, insulin secretion, and gene expression in cytokine-treated mouse islets, human islets, and STIM1 knockout (KO) 832/13 INS-1 β cells. In mouse islets treated with IL-1β, IFN-γ and TNF-⍺, NaB increased glucose-induced phase Ca2+ responses and restored Ca2+ oscillations. In IL-1β-treated INS-1 β cells, NaB rescued SOCE and ER Ca2+ store depletion, and increased glucose-stimulated insulin secretion (GSIS), while additionally improving cell viability and reducing apoptosis. Chronic (24hrs) but not acute (8hrs) NaB treatment prevented IL-1β-mediated reduction in the SOCE response, suggesting changes in gene expression may underlie these effects. To test this, RT-qPCR for SOCE molecular components was performed and revealed increased STIM1 expression in cytokine-treated mouse islets and INS-1 cells, while no change was observed in Orai1/2 levels. Consistent with these results, NaB was unable to restore SOCE in IL-1β-treated STIM1 KO INS-1 cells. Lastly, NaB treatment in human islets from donors with type 2 diabetes significantly increased levels of GSIS. Taken together, these data suggest that HDAC inhibition restores insulin secretion under pro-inflammatory conditions through improved SOCE and STIM1 upregulation. Disclosure C. Lee: None. T. Kono: None. S. A. Weaver: None. P. Sohn: None. C. Evans-molina: Advisory Panel; Self; Provention Bio, Inc., Consultant; Self; Dompe, Other Relationship; Self; Bristol-Myers Squibb Company, Nimbus Pharmaceuticals, Pfizer Inc.

638-P: A Novel, Long-Acting Dual Agonist for GIPR/GLP-1R, HISHS-2001, Demonstrates Effects on HbA1c and Weight Loss in the db/db Mouse Model of Type 2 Diabetes

HISHS-2001 is a novel long-acting, glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) dual receptor (R) agonist. In in vitro cAMP assays in human GIP/GLP-1 receptor-expressing cells, HISHS-2001 exerted half-maximal effects at concentrations of 2.3 nM and 4.1 nM on the receptors for GIP (GIPR) and GLP-1 (GLP-1R) respectively. After SC dosing every third day for four weeks, HISHS-2001 at 3, 10 and 21 nmol/kg demonstrated robust effects on HbA1c in db/db mice which were superior to semaglutide and tirzepatide (Table). The effect on body weight was more pronounced with HISHS-2001 than semaglutide and similar to tirzepatide which was associated with a reduction in food intake. Interestingly, HISHS-2001 led to a significant increase in uncoupling protein-1 (UCP-1) levels in intrascapular brown adipose tissue, in inguinal white adipose tissue and serum and liver fibroblast growth factor-21 (FGF-21) levels. A decrease in serum interleukin-6 (IL-6) level was also observed.In conclusion, HISHS-2001 is a potent, long acting GIP/GLP-1R dual agonist, which provides improved control of glucose homeostasis in diabetic mice compared to an existing GLP-1 agonist and a GIP/GLP-1R dual agonist.View largeDownload slideView largeDownload slide DisclosureV. S. Burade: None. A. Garcia-ocana: Consultant; Self; Sun Pharmaceutical Industries Ltd. R. E. Pratley: Other Relationship; Self; Hanmi Pharmaceutical, Merck Sharp & Dohme Corp., Metavention, Monster Energy Company, Inc., Novo Nordisk, Pfizer Inc., Poxel SA, Sanofi, Scohia Pharma Inc., Sun Pharmaceutical Industries Ltd. G. A. Rutter: Advisory Panel; Self; Sun Pharmaceutical Industries Ltd. T. Vilsbøll: Consultant; Self; Amgen Inc., AstraZeneca, Boehringer Ingelheim Pharmaceuticals, Inc., Bristol-Myers Squibb Company, Gilead Sciences, Inc., Lilly Diabetes, Merck Sharp & Dohme Corp., Mundipharma International, Novo Nordisk, Sanofi, Sun Pharmaceutical Industries Ltd. B. Thorens: Advisory Panel; Self; Sun Pharmaceutical Industries Ltd. R. Thennati: None.

SL010110, a lead compound, inhibits gluconeogenesis via SIRT2-p300-mediated PEPCK1 degradation and improves glucose homeostasis in diabetic mice.

Suppression of excessive hepatic gluconeogenesis is an effective strategy for controlling hyperglycemia in type 2 diabetes (T2D). In the present study, we screened our compounds library to discover the active molecules inhibiting gluconeogenesis in primary mouse hepatocytes. We found that SL010110 (5-((4-allyl-2-methoxyphenoxy) methyl) furan-2-carboxylic acid) potently inhibited gluconeogenesis with 3 μM and 10 μM leading to a reduction of 45.5% and 67.5%, respectively. Moreover, SL010110 caused suppression of gluconeogenesis resulted from downregulating the protein level of phosphoenolpyruvate carboxykinase 1 (PEPCK1), but not from affecting the gene expressions of PEPCK, glucose-6-phosphatase, and fructose-1,6-bisphosphatase. Furthermore, SL010110 increased PEPCK1 acetylation, and promoted PEPCK1 ubiquitination and degradation. SL010110 activated p300 acetyltransferase activity in primary mouse hepatocytes. The enhanced PEPCK1 acetylation and suppressed gluconeogenesis caused by SL010110 were blocked by C646, a histone acetyltransferase p300 inhibitor, suggested that SL010110 inhibited gluconeogenesis by activating p300. SL010110 decreased NAD+/NADH ratio, inhibited SIRT2 activity, and further promoted p300 acetyltransferase activation and PEPCK1 acetylation. These effects were blocked by NMN, an NAD+ precursor, suggested that SL010110 inhibited gluconeogenesis by inhibiting SIRT2, activating p300, and subsequently promoting PEPCK1 acetylation. In type 2 diabetic ob/ob mice, single oral dose of SL010110 (100 mg/kg) suppressed gluconeogenesis accompanied by the suppressed hepatic SIRT2 activity, increased p300 activity, enhanced PEPCK1 acetylation and degradation. Chronic oral administration of SL010110 (15 or 50 mg/kg) significantly reduced the blood glucose levels in ob/ob and db/db mice. This study reveals that SL010110 is a lead compound with a distinct mechanism of suppressing gluconeogenesis via SIRT2-p300-mediated PEPCK1 degradation and potent anti-hyperglycemic activity for the treatment of T2D.

Constructing a Smartphone-Controlled Semiautomatic Theranostic System for Glucose Homeostasis in Diabetic Mice.

With the development of mobile communication technology, smartphones have been used in point-of-care technologies (POCTs) as an important part of telemedicine. Using a multidisciplinary design principle coupling electrical engineering, software development, synthetic biology, and optogenetics, the investigators developed a smartphone-controlled semiautomatic theranostic system that regulates blood glucose homeostasis in diabetic mice in an ultraremote-control manner. The present chapter describes how the investigators tailor-designed the implant architecture "HydrogeLED," which is capable of coharboring a designer-cell-carrying alginate hydrogel and wirelessly powered far-red light LEDs. Using diabetes mellitus as a model disease, the in vivo expression of insulin or human glucagon-like peptide 1 (shGLP-1) from HydrogeLED implants could be controlled not only by pre-set ECNU-TeleMed programs, but also by a custom-engineered Bluetooth-active glucometer in a semiautomatic and glycemia-dependent manner. As a result, blood glucose homeostasis was semiautomatically maintained in diabetic mice through the smartphone-controlled semiautomatic theranostic system. By combining digital signals with optogenetically engineered cells, the present study provides a new method for the integrated diagnosis and treatment of diseases.

Mitochondrial Uncoupling Coordinated With PDH Activation Safely Ameliorates Hyperglycemia via Promoting Glucose Oxidation.

Uncoupling of mitochondrial respiration by chemical uncouplers has proven effective in ameliorating obesity, insulin resistance, and hyperglycemia. However, development of uncoupler-based therapy remains challenging due to its potentially lethal adverse effects. Here, we identify pyruvate dehydrogenase (PDH) as a key modifier of the toxicity profile of 2, 4-dinitrophenol (DNP), a prototypical mitochondrial uncoupler. PDH activation by dichloroacetic acid (DCA) protects mice from DNP-induced hyperlactacidemia, hyperthermia, and death while preserving the ability of DNP to promote fuel oxidation and improve insulin sensitivity in mice. Mechanistically, PDH activation switches on mitochondrial glucose oxidation to accommodate increased glycolytic flux, leading to reduced lactate secretion during uncoupler treatments. We devised a chemical screening strategy and discovered compound 6j as a dual-action compound that simultaneously activates PDH and uncouples mitochondrial respiration. Compound 6j exhibits an excellent efficacy and safety profile in restoring glucose homeostasis in diabetic mice. This work establishes a new principle to safely harness the power of chemical uncouplers for the treatment of metabolic disease.

Novel GLP-1 Analog Supaglutide Stimulates Insulin Secretion in Mouse and Human Islet Beta-Cells and Improves Glucose Homeostasis in Diabetic Mice.

Glucagon-like peptide-1 (GLP-1), an incretin hormone plays an important role in regulating glucose homeostasis. The therapeutic use of native GLP-1 is inadequate due to its short in vivo half-life. We recently developed a novel GLP-1 mimetics supaglutide, and demonstrated that this formulation retained native GLP-1 biological activities and possessed long-lasting GLP-1 actions. In this study, we further examined its abilities in regulating blood glucose in diabetic mice. We found that supaglutide stimulated insulin secretion in both mouse and human islets in a dose-dependent fashion. Oral glucose tolerance test conducted in normal ICR mice showed that supaglutide significantly decreased postprandial glucose excursions in a dose-dependent fashion. In type 2 diabetic db/db mice, a single-dose injection of supaglutide significantly decreased blood glucose levels, and this efficacy was lasted for at least 72 h in a dose-dependent fashion. During a 4-weeks intervention course supaglutide (twice injections per week) dose-dependently and significantly decreased fasting and random blood glucose levels in hyperglycemic db/db mice. Supaglutide, at a dose of 1.2 mg/kg, significantly reduced serum fructosamine levels. This was associated with significant enlargement of beta-cell mass, increased pancreatic insulin content, and increased plasma insulin level. Notably, during the intervention course supaglutide significantly reduced body-weight gain in these obese diabetic mice, associated with reduced fat mass (but not the lean mass), improved lipid profile, i.e., declined serum triglyceride, and free fatty acid levels compared to the placebo control. These finding reveals that supaglutide exerts beneficial effects in regulating blood glucose and lipid homeostasis in diabetic db/db mice.

TGR5 agonist ameliorates insulin resistance in skeletal muscles and improves glucose homeostasis in diabetic mice

Background and purposeTGR5 plays an important role in many physiological processes. However, the functions of TGR5 in the regulation of the glucose metabolism and insulin sensitivity in the skeletal muscles have not been fully elucidated. We synthesized MN6 as a potent and selective TGR5 agonist. Here, the effect of MN6 on insulin resistance in skeletal muscles was evaluated in diet-induced obese (DIO) mice and C2C12 myotubes, and the underlying mechanisms were explored. MethodsThe activation of MN6 on human and mouse TGR5 was evaluated by a cAMP assay in HEK293 cell lines stable expressing hTGR5/CRE or mTGR5/CRE cells. GLP-1 secretion was measured in NCI-H716 cells and CD1 mice. The acute and chronic effects of MN6 on regulating metabolic abnormalities were observed in ob/ob and DIO mice. 2-deoxyglucose uptake was examined in isolated skeletal muscles. Akt phosphorylation, glucose uptake and glycogen synthesis were examined to assess the effects of MN6 on palmitate-induced insulin resistance in C2C12 myotubes. ResultsMN6 potently activated human and mouse TGR5 with EC50 values of 15.9 and 17.9 nmol/L, respectively, and stimulated GLP-1 secretion in NCI-H716 cells and CD1 mice. A single oral dose of MN6 significantly decreased the blood glucose levels in ob/ob mice. Treatment with MN6 for 15 days reduced the fasting blood glucose and HbA1c levels in ob/ob mice. MN6 improved glucose and insulin tolerance and enhanced the insulin-stimulated glucose uptake of skeletal muscles in DIO mice. The palmitate-induced impairment of insulin-stimulated Akt phosphorylation, glucose uptake and glycogen synthesis in C2C12 myotubes could be prevented by MN6. The effect of MN6 on palmitate-impaired insulin-stimulated Akt phosphorylation was abolished by siRNA-mediated knockdown of TGR5 or by the inhibition of adenylate cyclase or protein kinase A, suggesting that this effect is dependent on the activation of TGR5 and the cAMP/PKA pathway. ConclusionsOur study identified that a TGR5 agonist could ameliorate insulin resistance by the cAMP/PKA pathway in skeletal muscles; this uncovered a new effect of the TGR5 agonist on regulating the glucose metabolism and insulin sensitivity in skeletal muscles and further strengthened its potential value for the treatment of type 2 diabetes.

Photoactivated cells link diagnosis and therapy.

A semiautonomous system enables implanted photoactivated cells to produce glucose-lowering hormones and maintain glucose homeostasis in diabetic mice (Shao et al, this issue).

Smartphone-controlled optogenetically engineered cells enable semiautomatic glucose homeostasis in diabetic mice.

With the increasingly dominant role of smartphones in our lives, mobile health care systems integrating advanced point-of-care technologies to manage chronic diseases are gaining attention. Using a multidisciplinary design principle coupling electrical engineering, software development, and synthetic biology, we have engineered a technological infrastructure enabling the smartphone-assisted semiautomatic treatment of diabetes in mice. A custom-designed home server SmartController was programmed to process wireless signals, enabling a smartphone to regulate hormone production by optically engineered cells implanted in diabetic mice via a far-red light (FRL)-responsive optogenetic interface. To develop this wireless controller network, we designed and implanted hydrogel capsules carrying both engineered cells and wirelessly powered FRL LEDs (light-emitting diodes). In vivo production of a short variant of human glucagon-like peptide 1 (shGLP-1) or mouse insulin by the engineered cells in the hydrogel could be remotely controlled by smartphone programs or a custom-engineered Bluetooth-active glucometer in a semiautomatic, glucose-dependent manner. By combining electronic device-generated digital signals with optogenetically engineered cells, this study provides a step toward translating cell-based therapies into the clinic.