Induced Glucose Uptake Research Articles

Saturated fatty acids inhibit unsaturated fatty acid induced glucose uptake involving GLUT10 and aerobic glycolysis in bovine granulosa cells

Fatty acids have been shown to modulate glucose metabolism in vitro and in vivo. However, there is still a need for substantial evidence and mechanistic understanding in many cell types whether both saturated and unsaturated fatty acids (SFAs and UFAs) pose a similar effect and, if not, what determines the net effect of fatty acid mixes on glucose metabolism. In the present study, we asked these questions by treating granulosa cells (GCs) with the most abundant non-esterified fatty acid species in bovine follicular fluid. Results revealed that oleic and alpha-linolenic acids (UFAs) significantly increased glucose consumption compared to palmitic and stearic acids (SFAs). A significant increase in lactate production, extracellular acidification rate, and decreased mitochondrial activity indicate glucose channeling through aerobic glycolysis in UFA treated GCs. We show that insulin independent glucose transporter GLUT10 is essential for UFA driven glucose consumption, and the induction of AKT and ERK signaling pathways necessary for GLUT10 expression. To mimic the physiological conditions, we co-treated GCs with mixes of SFAs and UFAs. Interestingly, co-treatments abolished the UFA induced glucose uptake and metabolism by inhibiting AKT and ERK phosphorylation and GLUT10 expression. These data suggest that the net effect of fatty acid induced glucose uptake in GCs is determined by SFAs under physiological conditions.

Chickpea proteins are potential sources of bioactive peptides that induce glucose uptake via AMP-activated protein kinase

Food proteins are a critical source of nutraceutical bioactive peptides that promote health and prevent diseases. Legume seed proteins have been extensively studied to produce peptides with diverse biological activities. Several legume protein hydrolysates and bioactive peptides have been identified that inhibit the activity of α-amylase, α-glucosidase, and dipeptidyl peptidase IV for the purpose of preventing diabetes. Herein, we observed that chickpea peptides (CPP), prepared using the enzymatic digestion of chickpea protein, induced glucose uptake in C2C12 myotubes. Further, liquid chromatography-tandem mass spectrometry and 2-deoxyglucose uptake assay were used to identify a bioactive CPP, defined as CPP737, REGDIIAVPTGVVF, a part of the legumin A-like protein. CPP737 induced AMP-activated protein kinase phosphorylation and glucose transporter type 4 membrane translocation, but not protein kinase B in C2C12 myotubes. Thus, chickpea protein is a potential source of bioactive peptides that can prevent insulin resistance and hyperglycemia through glucose uptake in the skeletal muscle.

Glycolipids Derived from the Korean Endemic Plant Aruncus aethusifolius Inducing Glucose Uptake in Mouse Skeletal Muscle C2C12 Cells.

Aruncus spp. has been used as a traditional folk medicine worldwide for its anti-inflammatory, hemostatic, and detoxifying properties. The well-known species A. dioicus var. kamtschaticus has long been used for multifunctional purposes in Eastern Asia. Recently, it was reported that its extract has antioxidant and anti-diabetic effects. In this respect, it is likely that other Aruncus spp. possess various biological activities; however, little research has been conducted thus far. The present study aims to biologically identify active compounds against diabetes in the Korean endemic plant A. aethusifolius and evaluate the underlying mechanisms. A. aethusifolius extract enhanced glucose uptake without toxicity to C2C12 cells. A bioassay-guided isolation of A. aethusifolius yielded two pure compounds, and their structures were characterized as glycolipid derivatives, gingerglycolipid A, and (2S)-3-linolenoylglycerol-O-β-d-galactopyranoside by an interpretation of nuclear magnetic resonance and high-resolution mass spectrometric data. Both compounds showed glucose uptake activity, and both compounds increased the phosphorylation levels of insulin receptor substrate 1 (IRS-1) and 5'-AMP-activated protein kinase (AMPK) and protein expression of peroxisome proliferator-activated receptor γ (PPARγ). Gingerglycolipid A docked computationally into the active site of IRS-1, AMPK1, AMPK2, and PPARγ (-5.8, -6.9, -6.8, and -6.8 kcal/mol).

Glucose uptake from the rhizosphere mediated by MdDOF3-MdHT1.2 regulates drought resistance in apple.

In plants under drought stress, sugar content in roots increases, which is important for drought resistance. However, the molecular mechanisms for controlling the sugar content in roots during response to drought remain elusive. Here, we found that the MdDOF3-MdHT1.2 module-mediated glucose influx into the root is essential for drought resistance in apple (Malus × domestica). Drought induced glucose uptake from the rhizosphere and up-regulated the transcription of hexose transporter MdHT1.2. Compared with the wild-type plants, overexpression of MdHT1.2 promoted glucose uptake from the rhizosphere, thereby facilitating sugar accumulation in root and enhancing drought resistance, whereas silenced plants showed the opposite phenotype. Furthermore, ATAC-seq, RNA-seq and biochemical analysis demonstrated that MdDOF3 directly bound to the promoter of MdHT1.2 and was strongly up-regulated under drought. Overexpression of MdDOF3 in roots improved MdHT1.2-mediated glucose transport capacity and enhanced plant resistance to drought, but MdDOF3-RNAihr apple plants showed the opposite phenotype. Moreover, overexpression of MdDOF3 in roots did not attenuate drought sensitivity in MdHT1.2-RNAi plants, which was correlated with a lower glucose uptake capacity and glucose content in root. Collectively, our findings deciphered the molecular mechanism through which glucose uptake from the rhizosphere is mediated by MdDOF3-MdHT1.2, which acts to modulate sugar content in root and promote drought resistance.

Using a Combination of Indirect Calorimetry, Infrared Thermography, and Blood Glucose Levels to Measure Brown Adipose Tissue Thermogenesis in Humans.

In mammals, brown adipose tissue (BAT) is activated rapidly in response to cold in order to maintain body temperature. Although BAT has been studied greatly in small animals, it is difficult to measure the activity of BAT in humans. Therefore, little is known about the heat-generating capacity and physiological significance of BAT in humans, including the degree to which components of the diet can activate BAT. This is due to the limitations in the currently most used method to assess the activation of BAT-radiolabeled glucose (fluorodeoxyglucose or 18FDG) measured by positron emission tomography-computerized tomography (PET-CT). This method is usually performed in fasted subjects, as feeding induces glucose uptake by the muscles, which can mask the glucose uptake into the BAT. This paper describes a detailed protocol for quantifying total-body human energy expenditure and substrate utilization from BAT thermogenesis by combining indirect calorimetry, infrared thermography, and blood glucose monitoring in carbohydrate-loaded adult males. To characterize the physiological significance of BAT, measures of the impact of BAT activity on human health are critical. We demonstrate a protocol to achieve this by combining carbohydrate loading and indirect calorimetry with measurements of supraclavicular changes in temperature. This novel approach will help to understand the physiology and pharmacology of BAT thermogenesis in humans.

The Synergistic Action of Metformin and Glycyrrhiza uralensis Fischer Extract Alleviates Metabolic Disorders in Mice with Diet-Induced Obesity.

Metformin, an antidiabetic drug, and Glycyrrhiza uralensis Fischer (GU), an oriental medicinal herb, have been reported to exert anti-obesity effects. This study investigated the synergistic action of metformin and GU in improving diet-induced obesity. Mice were fed a normal diet, a high-fat diet (HFD), or HFD + 0.015% GU water extract for 8 weeks. The HFD and GU groups were then randomly divided into two groups and fed the following diets for the next 8 weeks: HFD with 50 mg/kg metformin (HFDM) and GU with 50 mg/kg metformin (GUM). GUM prevented hepatic steatosis and adiposity by suppressing expression of mRNAs and enzyme activities related to lipogenesis in the liver and upregulating the expression of adipocyte mRNAs associated with fatty acid oxidation and lipolysis, and as a result, improved dyslipidemia. Moreover, GUM improved glucose homeostasis by inducing glucose uptake in tissues and upregulating mRNA expressions associated with glycolysis in the liver and muscle through AMP-activated protein kinase activation. GUM also improved inflammation by increasing antioxidant activity in the liver and erythrocytes and decreasing inflammatory cytokine productions. Here, we demonstrate that GU and metformin exert synergistic action in the prevention of obesity and its complications.

Acute cytokine treatment stimulates glucose uptake and glycolysis in human keratinocytes.

During inflammation, cellular glucose uptake and glycolysis are upregulated to meet an increased energy demand. For example, keratinocyte glycolysis is essential for progression of psoriasis. Therefore, understanding the regulation of glucose metabolism in keratinocytes is of importance. Here, we show that the pro-inflammatory cytokines IFNγ and TNF together rapidly induce glucose uptake, glycolysis, and glycolytic capacity in cultured keratinocytes. Furthermore, we found that acute IFNγ and TNF stimulation induces glucose transporter 4 (GLUT4) translocation to the plasma membrane and engages AMPK-dependent intracellular signaling. Together, these findings suggest acute cytokine-induced glucose metabolism in keratinocytes could contribute to inflammation in psoriatic disease, and that GLUT4 is involved in these processes.

Quercetin acts via the G3BP1/YWHAZ axis to inhibit glycolysis and proliferation in oral squamous cell carcinoma

There is increasing evidence that the GTPase-activating protein SH3 domain-binding protein 1 (G3BP1) plays important roles in the formation of various tumors. However, the biological functions and mechanism of G3BP1 in promoting the progression of oral squamous cell carcinoma remain largely unknown. The impacts of quercetin on glycolysis and proliferation of the CAL27 oral squamous cell carcinoma line were investigated, and the mediating role of the G3BP1/YWHAZ pathway was explored. CAL27 cells stably over- or underexpressing G3BP1 were treated with quercetin, and then cell proliferation was assayed together with the expression of proteins involved in glucose uptake, glycolysis, and lactate production, as well as the activity of hexokinase, pyruvate kinase, and lactate dehydrogenase. CAL27 cells expressed G3BP1 and YWHAZ at significantly higher levels than normal oral squamous cells. CAL27 cells showed the highest expression of both proteins among the three carcinoma lines (TSCCA, SCC15, 42 CAL27). Overexpressing G3BP1 in CAL27 cells markedly induced glucose uptake, glycolysis, cell proliferation, and YWHAZ expression. Knocking down G3BP1 or YWHAZ exerted the opposite effects, which were similar to the effects of inhibiting glycolysis. Quercetin repressed glucose uptake, glycolysis, cell proliferation, and G3BP1/YWHAZ signaling in a dose-dependent way, and these effects were antagonized by G3BP1 overexpression. Quercetin can inhibit glycolysis and cell proliferation of oral squamous cell carcinoma, apparently by inhibiting the G3BP1/YWHAZ axis.

BAFF 60‐mer binding to BAFF receptor 3 utilizes the NF‐κB1 signaling pathway to hyperactivate B cells

B cell activating factor (BAFF) is a critical cytokine for survival, differentiation, proliferation, and antibody production of B cells. Abnormal B cell activation by BAFF has been implicated in diseases such as Systemic Lupus Erythematous (SLE) and rheumatoid arthritis. BAFF is expressed as a membrane bound 3‐mer and then cleaved to its soluble form where it can form a 60‐mer. It is not completely understood how the 3‐mer versus 60‐mer form can differentially activate B cells. Using surface plasmon resonance (SPR), we determined that human BAFF 60‐mer bound strongly to soluble murine BAFF receptor 3 (BR3), Transmembrane activator and CAML interactor (TACI), and B‐cell maturation antigen (BCMA), while human BAFF 3‐mer only bound to soluble murine BR3. We treated purified mouse splenic B cells with BAFF 3‐mer, BAFF 60‐mer, or left untreated in the presence of a control antibody or mBAFFR‐Fc, which only blocks BAFF binding to BR3. A global transcriptomics study revealed that BAFF 60‐mer upregulated genes involved in B cell activation and NF‐κB signaling, compared to BAFF 3‐mer treatment. mBAFFR‐Fc treatment reduced the expression of many of the genes involved in B cell activation and NF‐κB signaling. We next assessed B cell energy metabolism utilizing the Seahorse mitochondrial stress test and glycolysis stress test. B cells treated with BAFF 60‐mer had significantly increased glucose oxidation by oxidative phosphorylation (OXPHOS) and aerobic glycolysis compared to the 3‐mer treated B cells, and this result was attenuated by the addition of mBAFFR‐Fc. Treatment with inhibitors that block the NF‐κB pathway (using BMS) or only the NF‐κB1 pathway (using BI 605906) attenuated OXPHOS and aerobic glycolysis. BAFF 60‐mer treatment increased mitochondrial density and mitochondrial membrane potential (MMP), while decreasing cellular reactive oxygen species (ROS) production indicating generation of healthier mitochondria. Treatment with mBAFFR‐Fc or BMS impaired the BAFF 60‐mer mediated changes to the mitochondrial density, MPP, and ROS. Interestingly, a mitochondrial substrate metabolism assay found that glycerol 3‐PO4 and succinate were significantly utilized by the B cells. While the addition of BAFF, mBAFFR‐Fc, or BMS did not significantly affect glycerol 3‐PO4 usage, succinate utilization significantly increased after BAFF 60‐mer treatment. BAFF 60‐mer treatment increased glucose uptake which was reduced after mBAFFR‐Fc treatment. In contrast, BMS attenuated both the basal and BAFF 60‐mer induced glucose uptake. Altogether, these results show that BAFF 60‐mer binding, via the BR3, hyperactivates B cells by increasing metabolic activity, mitochondrial health, succinate utilization, and glucose uptake as a result of NF‐κB1 activation. Furthermore, our research suggests that BAFF 60‐mer formation may be a potential target for future anti‐BAFF biologics for diseases such as SLE.

Insulin mimetic lanostane triterpenes from the cultivated mushroom Ganoderma orbiforme

• Three triterpenes derivatives were isolated from the cultivated fruiting bodies of Ganoderma orbiforme . • The triterpenes induced glucose uptake in a zebrafish-based assay. • The triterpenes also showed an inhibitory effect on nitric oxide production in LPS-induced BV-2 microglia cells. Two new lanostane triterpenes, ganorbifoins A and B ( 1 - 2 ), together with the known compound (25S,3′S)-(+)-12α-hydroxy-3α-(3′-hydroxy-4′-methoxycarbonyl-3′-methylbutiryloxy)-24-methyllanosta-824-(31)-dien-26-oic acid ( 3 ) were isolated from the cultivated fruiting bodies of Ganoderma orbiforme . The structures of isolates were determined by extensive analysis of NMR and HRESIMS. All compounds induced glucose uptake in zebrafish-based system at the concentration of 10 μM. And the best performing compound is ganorbifoin A. Compounds 2 and 3 exhibited an inhibitory effect on nitric oxide production in LPS-induced BV-2 microglia cells at the concentration of 20 μ M.

Ebselen enhances insulin sensitivity and decreases oxidative stress by inhibiting SHIP2 and protects from inflammation in diabetic mice

Ebselen, a multifunctional organoselenium compound, has been recognized as a potential treatment for diabetes-related disorders. However, the underlying mechanisms whereby ebselen regulates metabolic pathways remain elusive. We discovered that ebselen inhibits lipid phosphatase SHIP2 (Src homology 2 domain-containing inositol-5-phosphatase 2), an emerging drug target to ameliorate insulin resistance in diabetes. We found that ebselen directly binds to and inhibits the catalytic activity of the recombinant SHIP2 phosphatase domain and SHIP2 in cultured cells, the skeletal muscle and liver of the diabetic db/db mice, and the liver of the SHIP2 overexpressing (SHIP2-Tg) mice. Ebselen increased insulin-induced Akt phosphorylation in cultured myotubes, enhanced insulin sensitivity and protected liver tissue from lipid peroxidation and inflammation in the db/db mice, and improved glucose tolerance more efficiently than metformin in the SHIP2-Tg mice. SHIP2 overexpression abrogated the ability of ebselen to induce glucose uptake and reduce ROS production in myotubes and blunted the effect of ebselen to inhibit SHIP2 in the skeletal muscle of the SHIP2-Tg mice. Our data reveal ebselen as a potent SHIP2 inhibitor and demonstrate that the ability of ebselen to ameliorate insulin resistance and act as an antioxidant is at least in part mediated by the reduction of SHIP2 activity.

New Intracellular Peptide Derived from Hemoglobin Alpha Chain Induces Glucose Uptake and Reduces Blood Glycemia.

Intracellular peptides were shown to derive from proteasomal degradation of proteins from mammalian and yeast cells, being suggested to play distinctive roles both inside and outside these cells. Here, the role of intracellular peptides previously identified from skeletal muscle and adipose tissues of C57BL6/N wild type (WT) and neurolysin knockout mice were investigated. In differentiated C2C12 mouse skeletal muscle cells, some of these intracellular peptides like insulin activated the expression of several genes related to muscle contraction and gluconeogenesis. One of these peptides, LASVSTVLTSKYR (Ric4; 600 µg/kg), administrated either intraperitoneally or orally in WT mice, decreased glycemia. Neither insulin (10 nM) nor Ric4 (100 µM) induced glucose uptake in adipose tissue explants obtained from conditional knockout mice depleted of insulin receptor. Ric4 (100 µM) similarly to insulin (100 nM) induced Glut4 translocation to the plasma membrane of C2C12 differentiated cells, and increased GLUT4 mRNA levels in epididymal adipose tissue of WT mice. Ric4 (100 µM) increased both Erk and Akt phosphorylation in C2C12, as well as in epididymal adipose tissue from WT mice; Erk, but not Akt phosphorylation was activated by Ric4 in tibial skeletal muscle from WT mice. Ric4 is rapidly degraded in vitro by WT liver and kidney crude extracts, such a response that is largely reduced by structural modifications such as N-terminal acetylation, C-terminal amidation, and substitution of Leu8 for DLeu8 (Ac-LASVSTV[DLeu]TSKYR-NH2; Ric4-16). Ric4-16, among several Ric4 derivatives, efficiently induced glucose uptake in differentiated C2C12 cells. Among six Ric4-derivatives evaluated in vivo, Ac-LASVSTVLTSKYR-NH2 (Ric4-2; 600 µg/kg) and Ac-LASVSTV[DLeu]TSKYR (Ric4-15; 600 µg/kg) administrated orally efficiently reduced glycemia in a glucose tolerance test in WT mice. The potential clinical application of Ric4 and Ric4-derivatives deserves further attention.

β-Catenin is required for optimal exercise- and contraction-stimulated skeletal muscle glucose uptake.

Loss of β-catenin impairs in vivo and isolated muscle exercise/contraction-stimulated glucose uptake. β-Catenin is required for exercise-induced skeletal muscle actin cytoskeleton remodelling. β-Catenin675 phosphorylation during exercise may be intensity dependent. The conserved structural protein β-catenin is an emerging regulator of vesicle trafficking in multiple tissues and supports insulin-stimulated glucose transporter 4 (GLUT4) translocation in skeletal muscle by facilitating cortical actin remodelling. Actin remodelling may be a convergence point between insulin and exercise/contraction-stimulated glucose uptake. Here we investigated whether β-catenin is involved in regulating exercise/contraction-stimulated glucose uptake. We report that the muscle-specific deletion of β-catenin induced in adult mice (BCAT-mKO) impairs both exercise- and contraction (isolated muscle)-induced glucose uptake without affecting running performance or canonical exercise signalling pathways. Furthermore, high intensity exercise in mice and contraction of myotubes and isolated muscles led to the phosphorylation of β-cateninS675 , and this was impaired by Rac1 inhibition. Moderate intensity exercise in control and Rac1muscle-specific knockout mice did not induce muscle β-cateninS675 phosphorylation, suggesting exercise intensity-dependent regulation of β-cateninS675 . Introduction of a non-phosphorylatable S675A mutant of β-catenin into myoblasts impaired GLUT4 translocation and actin remodelling stimulated by carbachol, a Rac1 and RhoA activator. Exercise-induced increases in cross-sectional phalloidin staining (F-actin marker) of gastrocnemius muscle was impaired in muscle from BCAT-mKO mice. Collectively our findings suggest that β-catenin is required for optimal glucose transport in muscle during exercise/contraction, potentially via facilitating actin cytoskeleton remodelling.

Invivo glucose imaging in multiple model organisms with an engineered single-wavelength sensor.

Glucose is arguably the most important molecule in metabolism, and its dysregulation underlies diabetes. We describe a family of single-wavelength genetically encoded glucose sensors with a high signal-to-noise ratio, fast kinetics, and affinities varying over four orders of magnitude (1μM to 10mM). The sensors allow mechanistic characterization of glucose transporters expressed in cultured cells with high spatial and temporal resolution. Imaging of neuron/glia co-cultures revealed ∼3-fold faster glucose changes in astrocytes. In larval Drosophila central nervous system explants, intracellular neuronal glucose fluxes suggested a rostro-caudal transport pathway in the ventral nerve cord neuropil. In zebrafish, expected glucose-related physiological sequelae of insulin and epinephrine treatments were directly visualized. Additionally, spontaneous muscle twitches induced glucose uptake in muscle, and sensory and pharmacological perturbations produced large changes in the brain. These sensors will enable rapid, high-resolution imaging of glucose influx, efflux, and metabolism in behaving animals.

Myosin 1c: A novel regulator of glucose uptake in brown adipocytes

ObjectiveThe potential of brown adipose tissue (BAT) to influence energy homeostasis in animals and humans is encouraging as this tissue can increase fatty acid and glucose utilization to produce heat through uncoupling protein 1 (UCP1), but the actual mechanism of how the cell regulates glucose uptake is not fully understood. Myosin 1c (Myo1c) is an unconventional motor protein involved in several cellular processes, including insulin-mediated glucose uptake via GLUT4 vesicle fusion in white adipocytes, but its role in glucose uptake in BAT has not previously been investigated. MethodsUsing the specific inhibitor pentachloropseudilin (PClP), a neutralizing antibody assay, and siRNA, we examined the role of Myo1c in mechanisms leading to glucose uptake both in vitro in isolated mouse primary adipocytes and in vivo in mice. ResultsOur results show that inhibition of Myo1c removes insulin-stimulated glucose uptake in white adipocytes, while inducing glucose uptake in brown adipocytes, independent of GLUT4, by increasing the expression, translation, and translocation of GLUT1 to the plasma membrane. Inhibition of Myo1c leads to the activation of PKA and downstream substrates p38 and ATF-2, which are known to be involved in the expression of β-adrenergic genes. ConclusionsMyo1c is a PKA repressor and regulates glucose uptake into BAT.

Natural Compound 3β,7β,25-trihydroxycucurbita-5,23(E)-dien-19-al from Momordica charantia Acts as PPARγ Ligand.

Momordica charantia is a popular vegetable associated with effective complementary and alternative diabetes management in some parts of the world. However, the molecular mechanism is less commonly investigated. In this study, we investigated the association between a major cucurbitane triterpenoid isolated from M. charantia, 3β,7β,25-trihydroxycucurbita-5,23(E)-dien-19-al (THCB) and peroxisome proliferator activated receptor gamma (PPARγ) activation and its related activities using cell culture and molecular biology techniques. In this study, we report on both M. charantia fruit crude extract and THCB in driving the luciferase activity of Peroxisome Proliferator Response Element, associated with PPARγ activation. Other than that, THCB also induced adipocyte differentiation at far less intensity as compared to the full agonist rosiglitazone. In conjunction, THCB treatment on adipocytes also resulted in upregulation of PPAR gamma target genes expression; AP2, adiponectin, LPL and CD34 at a lower magnitude compared to rosiglitazone’s induction. THCB also induced glucose uptake into muscle cells and the mechanism is via Glut4 translocation to the cell membrane. In conclusion, THCB acts as one of the many components in M. charantia to induce hypoglycaemic effect by acting as PPARγ ligand and inducing glucose uptake activity in the muscles by means of Glut4 translocation.

Oxidovanadium(IV/V) complexes bound with a ONS donor backbone: The search for therapeutic versatility in one class of compounds

Among the multifarious approaches to treat health challenges such as microbial infections, cancers, and diabetes, metallotherapy is a very significant one. Many transition metal‐based candidates have been previously developed that displayed promising therapeutic interests. Vanadium is one such biologically important transition metal, and in the present work, we have developed potent bioactive vanadium complexes, namely, [{VVO(hpdbal‐smdt)}2μ‐O] (1), [VVO(hpdbal‐smdt)(bha)] (2), [VVO(hpdbal‐smdt)(cat)] (3), [VIVO(hpdbal‐smdt)(phen)] (4), and [VIVO(hpdbal‐smdt)(bipy)] (5), which were synthesized using a ONS donor‐based ligand, H2hpdbal‐smdt (H2L), and [VO(acac)2] alongside secondary ligands, benzohydroxamic acid (bha), catechol (cat), 1,10‐phenanthroline (phen), and 2,2′‐bipyridyl (bipy), respectively. The complexes were mainly characterized using electron paramagnetic resonance (EPR), 1H‐NMR, 13C‐NMR, and infrared (IR) spectroscopy techniques. The ligand was additionally characterized using a single‐crystal X‐ray diffraction (XRD) technique. The compounds were tested for their therapeutic versatility, namely, glucose uptake activity, free radical scavenging activity, and growth inhibitory action towards resilient microbial strains and liver cancer cells. The oxo‐bridged dinuclear vanadium complex (1) showed promising growth inhibitory activity against Pseudomonas aeruginosa bacterial species. Secondary ligand tethered compound (2) displayed notable toxicity against the human liver cancer cells. All complexes induced glucose uptake by the insulin‐resistant cells and exhibited moderate to high antioxidant potential. pH titration and interaction study of these complexes with bovine serum albumin were conducted to investigate solution stability and protein binding properties.

A short peptide of the C-terminal class Y helices of apolipoprotein A-I has preserved functions in cholesterol efflux and in vivo metabolic control

Apolipoprotein A-I (ApoA-I) of high-density lipoprotein (HDL) induces glucose uptake by muscle tissues and stimulates pancreatic insulin secretion, and also facilitates cholesterol transport in circulation, and is explored for anti-diabetic and anti-atherosclerotic treatments. As the better alternative to complex protein–lipid formulations it was recently established that the C-terminal region of the ApoA-I protein singly improves the metabolic control and prevents formation of atherosclerotic plaques. Additional investigations of peptides based on the ApoA-I structure may lead to novel anti-diabetic drugs. We here investigate a short peptide (33mer, RG33) that corresponds to the two last helical segments (aa 209–241) of the ApoA-I structure (so-called class Y-helices which forms amphipathic helices) for stability and solubility in serum, for in vitro cholesterol efflux capability, and for providing in vivo glucose control in an insulin resistant mouse model. The RG33 peptide efficiently solubilizes lipid-vesicles, and promotes the efflux of cholesterol from cultured macrophages. The efflux capacity is significantly increased in the presence of lipids compared to non-lipidated RG33. Finally, acute treatment with the RG33 peptide significantly improves the glucose clearance capacity of insulin resistant mice. The impact of the RG33 peptide on glucose control and cholesterol transport, as well as the physicochemical properties, makes it a good candidate for translational exploration of its therapeutic potential in diabetes treatment.

The autocrine role of FGF21 in cultured adipocytes.

Exposure to cold alters glucose and lipid metabolism of white and brown adipose tissue via activation of β-adrenergic receptor (ADRB). Fibroblast growth factor 21 (FGF21) has been shown to be locally released from adipose tissue upon activation of ADRBs and FGF21 increases glucose uptake in adipocytes. Therefore, FGF21 may play an autocrine role in inducing glucose uptake after β-adrenergic stimulation. To determine the putative autocrine role of FGF21, we stimulated three different types of adipocytes in vitro with Isoprenaline (Iso), an ADRB agonist, in the presence or absence of the FGF receptor (FGFR) inhibitor PD 173074. The three cell lines represent white (3T3-L1), beige (ME3) and brown (WT-1) adipocyte phenotypes, respectively. All three cells systems expressed β-klotho (KLB) and FGFR1 after differentiation and treatment with recombinant FGF21 increased glucose uptake in 3T3-L1 and WT-1 adipocytes, while no significant effect was observed in ME3. Oppositely, all three cell lines responded to Iso treatment and an increase in glucose uptake and lipolysis were observed. Interestingly, in response to the Iso treatment only the WT-1 adipocytes showed an increase in FGF21 in the medium. This was consistent with the observation that PD 173074 decreased Iso-induced glucose uptake in the WT-1 adipocytes. This suggests that FGF21 plays an autocrine role and increases glucose uptake after β-adrenergic stimulation of cultured brown WT-1 adipocytes.

1725-P: Viral Insulins as Agonists and Antagonists on Insulin/IGF-1 Receptors

Recently, we identified four insulin/IGF-1 like peptides (VILPs) in the sequence of viruses belonging to the Iridoviridae family. These VILPs show up to 50% homology with the sequence of the human insulin/IGF-1. Moreover, the predicted tertiary structures and major receptor binding residues are conserved between the VILPs and insulin/IGF-1. Although these viruses are known to infect primarily fish, sequences of VILPs have been found in human blood and feces. VILPs can interact with the human and murine insulin and IGF-1 receptors and induce the activation of their downstream signaling. Functionally, VILPs are able to induce glucose uptake and cell proliferation. VILPs can be synthesized as a single-chain (SC) or double-chain (DC) peptides, i.e., more IGF-1 like or more insulin like structures. In the present study, we show that SC and DC forms of lymphocystis disease virus (LCDV-1) VILP interact differently with the human insulin and IGF-1 receptor. Competition binding assay reveals that SC is more potent than DC in binding to the IGF-1 receptor. In vivo, following i.p. injection in mice both LCDV-1 SC and DC produced similar mild decreases in blood glucose compared to insulin, even at a 166-fold excess. In vitro, however, DC LCDV1-VILP acts as a weak agonist to stimulation of IGF1R, whereas SC LCDV-VILP serves as a strong antagonism effect on the IGF-1 receptor. Thus, the activation of the IGF1R by IGF-1 is strongly repressed by the SC LCDV-1 VILP, even at equal concentrations. This antagonistic action of SC VILP is restricted to the IGF1R and does not affect insulin receptor. As a functional consequence of IGF1R blockade, SC LCDV-1 VILP inhibits IGF-1 stimulated migration of a cervical cancer cell line. In summary, we have shown that SC VILP may provide a novel inhibitor of IGF1R signaling and IGF-1 action on tumor cell migration, with minimal effects on glucose metabolism, thus providing a potentially unique reagent for treatment of IGF-1 sensitive tumors. Disclosure F. Moreau: None. B. Brandao: None. C. Cederquist: None. T.M. Batista: None. R. DiMarchi: Employee; Self; Novo Nordisk Inc. E. Altindis: None. C. Kahn: Advisory Panel; Self; ERX Pharmaceuticals, Kaleido Biosciences. Consultant; Self; AntriaBio, Flagship Pioneering, Sana-Cobalt.