Insulin Receptor Phosphorylation Research Articles

Identification of 1,3,4-Thiadiazolyl-Containing Thiazolidine-2,4-dione Derivatives as Novel PTP1B Inhibitors with Antidiabetic Activity.

Forty-one 1,3,4-thiadiazolyl-containing thiazolidine-2,4-dione derivatives (MY1-41) were designed and synthesized as protein tyrosine phosphatase 1B (PTP1B) inhibitors with activity against diabetes mellitus (DM). All synthesized compounds (MY1-41) presented potential PTP1B inhibitory activities, with half-maximal inhibitory concentration (IC50) values ranging from 0.41 ± 0.05 to 4.68 ± 0.61 μM, compared with that of the positive control lithocholic acid (IC50 = 9.62 ± 0.14 μM). The most potent compound, MY17 (IC50 = 0.41 ± 0.05 μM), was a reversible, noncompetitive inhibitor of PTP1B. Circular dichroism spectroscopy and molecular docking were employed to analyze the binding interaction between MY17 and PTP1B. In HepG2 cells, MY17 treatment could alleviate palmitic acid (PA)-induced insulin resistance by upregulating the expression of phosphorylated insulin receptor substrate and protein kinase B. In vivo, oral administration of MY17 could reduce the fasting blood glucose level and improve glucose tolerance and dyslipidemia in mice suffering from DM.

Effects of CBD on the Phosphorylation of Cardiac Insulin Receptor in Rat Model of Metabolic Syndrome

Metabolic syndrome (MetS) comprises a cluster of conditions that include obesity, insulin resistance, dyslipidemia, hypertension, pro-inflammation, and pro-thrombosis. In the United States, approximately one in three adults is afflicted with MetS. If left unmanaged, it can lead to type 2 diabetes (T2D), which would increase the risk of cardiovascular diseases (CVD). The insulin signaling pathway is critical to regulate glucose homeostasis in the body. During insulin resistance, the pathway is downregulated, and glucose remains in the bloodstream leading to a hyperglycemic state. Recent studies on the benefits of cannabidiol (CBD) have shown it can mitigate CVD risk factors, but its impact on glucose metabolism within the heart remains unclear. To investigate this, the Otsuka Long Evans Tokushima Fatty (OLETF) rat, a model of MetS, and its healthy strain-control, the Long Evans Tokushima Otsuka (LETO) rat, were used. Rats were assigned to three groups (n=8/group): (1) untreated LETO, (2) untreated OLETF, and (3) OLETF + H4CBD (200mg/kg/day x 4 weeks). CBD treatment did not impact the nascent insulin receptor nor the nascent protein kinase B, but the effects of CBD on the phosphorylation and activation of these insulin signaling components have yet to be determined (analyses ongoing). Because CBD has been shown to improve glucose homeostasis previously, we anticipate it is by increasing the activation by phosphorylation of the insulin receptor. A better examination of the effects of CBD on the insulin signaling pathway in the heart will provide greater insight on its therapeutic potential during diabetic cardiomyopathy. USDA Hispanic Education Training Program, Center for Medical Cannabis Research. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Inhibition of neuraminidase-1 sialidase activity by interfering peptides impairs insulin receptor activity in vitro and glucose homeostasis in vivo

Neuraminidases also called sialidases are glycosidases which catalyze the removal of terminal sialic acid residues from glycoproteins, glycolipids and oligosaccharides. Mammalian Neuraminidase-1 (NEU-1) participates in regulation of cell surface receptors such as insulin receptor (IR), epithelial growth factor receptor, low density lipoprotein receptor and toll like receptor 4. At the plasma membrane, NEU-1 can be associated with the elastin-binding protein and the carboxypeptidase protective protein/cathepsin A to constitute the elastin receptor complex. In this complex, NEU-1 is essential for elastogenesis, signal transduction through this receptor and for biological effects of the elastin-derived peptides on atherosclerosis, thrombosis, insulin resistance, non-alcoholic steatohepatitis and cancers. This is why research teams are developing inhibitors targeting this sialidase. Previously, we developed interfering peptides to inhibit the dimerization and the activation of NEU-1. In this study, we investigated the effects of these peptides on IR activation in vitro and in vivo. Using cellular overexpression and endogenous expression models of NEU-1 and IR (COS-7 and HepG2 cells respectively), we have shown that interfering peptides inhibit NEU-1 dimerization and sialidase activity which results in a reduction of IR phosphorylation. These results demonstrated that NEU-1 positively regulates IR phosphorylation and activation in our conditions. In vivo, biodistribution study showed that interfering peptides are well distributed in mice. Treatment of C57Bl/6 mice during eight weeks with interfering peptides induces a hyperglycemic effect in our experimental conditions. Altogether, we report here that inhibition of NEU-1 sialidase activity by interfering peptides decreases IR activity in vitro and glucose homeostasis in vivo.

Elevated levels of alcohol dehydrogenase aggravate ethanol-evoked cardiac remodeling and contractile anomalies through FKBP5-yap-mediated regulation of ferroptosis and ER stress

Alcohol intake provokes severe organ injuries including alcoholic cardiomyopathy with hallmarks of cardiac remodeling and contractile defects. This study examined the toxicity of facilitated ethanol metabolism in alcoholism-evoked changes in myocardial morphology and contractile function, insulin signaling and various cell death domains using cardiac-selective overexpression of alcohol dehydrogenase (ADH). WT and ADH mice were offered an alcohol liquid diet for 12 weeks prior to assessment of cardiac geometry, function, ER stress, apoptosis and ferroptosis. Alcohol intake provoked pronounced glucose intolerance, cardiac remodeling and contractile anomalies with apoptosis, ER stress, and ferroptosis, the effects were accentuated by ADH with the exception of global glucose intolerance. Hearts from alcohol ingesting mice displayed dampened insulin-stimulated phosphorylation of insulin receptor (tyr1146) and IRS-1 (tyrosine) along with elevated IRS-1 serine phosphorylation, the effect was augmented by ADH. Alcohol challenge dampened phosphorylation of Akt and GSK-3β, and increased phosphorylation of c-Jun and JNK, the effects were accentuated by ADH. Alcohol challenge promoted ER stress, FK506 binding protein 5 (FKBP5), YAP, apoptosis and ferroptosis, the effects were exaggerated by ADH. Using a short-term ethanol challenge model (3 g/kg, i.p., twice in three days), we found that inhibition of FKBP5-YAP signaling or facilitated ethanol detoxification by Alda-1 alleviated ethanol cardiotoxicity. In vitro study revealed that the ethanol metabolite acetaldehyde evoked cardiac contractile anomalies, lipid peroxidation, and apoptosis, the effects of which were mitigated by Alda-1, inhibition of ER stress, FKBP5 and YAP. These data suggest that facilitated ethanol metabolism via ADH exacerbates alcohol-evoked myocardial remodeling, functional defects, and insulin insensitivity possibly through a FKBP5-YAP-associated regulation of ER stress and ferroptosis.

Methylparaben induces hepatic glycolipid metabolism disorder by activating the IRE1α-XBP1 signaling pathway in male mice

Methylparaben (MP), a preservative widely used in daily supplies, exists in both the environment and the human body. However, the potential health risks posed by MP remain unclear. This study aimed to unravel the mechanisms by which MP disrupts glucose and lipid homeostasis. For this, we administered MP to mice and observed changes in glucose and lipid metabolism. MP exposure led to hyperglycemia, hyperlipidemia, visceral organ injury, and hepatic lipid accumulation. RNA sequencing results from mice livers indicated a close association between MP exposure and endoplasmic reticulum (ER) stress, inflammatory response, and glucose and lipid homeostasis. Western blotting and quantitative reverse transcription–polymerase chain reaction revealed that MP activated ER stress, particularly the inositol-requiring enzyme 1 (IRE1)/X-box binding protein 1 (XBP1) pathway, which further promoted the activation of the nuclear factor-kappa B (NF-κB) and mitogen-activated protein kinase (MAPK) pathways. The activation of these pathways phosphorylated insulin receptor substrate-1 (IRS1) (ser 307), resulting in decreased phosphorylation of protein kinase B (Akt) (ser 473), leading to insulin resistance. Additionally, MP exposure promoted lipogenesis through ER stress. To explore potential remedies, we administered the ER stress inhibitor 4-phenylbutyric acid (4-PBA) and the IRE1α-XBP1 pathway inhibitor toyocamycin to mice, both of which protected against metabolic disorders and organ injury caused by MP. These findings suggest that MP induces disruptions in glucose and lipid metabolism through ER stress, primarily through the IRE1α-XBP1 pathway.

Tryptophanylation of insulin receptor by WARS attenuates insulin signaling.

Increased circulating amino acid levels have been linked to insulin resistance and development of type 2 diabetes (T2D), but the underlying mechanism remains largely unknown. Herein, we show that tryptophan modifies insulin receptor (IR) to attenuate insulin signaling and impair glucose uptake. Mice fed with tryptophan-rich chow developed insulin resistance. Excessive tryptophan promoted tryptophanyl-tRNA synthetase (WARS) to tryptophanylate lysine 1209 of IR (W-K1209), which induced insulin resistance by inhibiting the insulin-stimulated phosphorylation of IR, AKT, and AS160. SIRT1, but not other sirtuins, detryptophanylated IRW-K1209 to increase the insulin sensitivity. Collectively, we unveiled the mechanisms of how tryptophan impaired insulin signaling, and our data suggested that WARS might be a target to attenuate insulin resistance in T2D patients.

Hydroalcoholic extract from Sechium edule (Jacq.) S.w. root reverses oleic acid-induced steatosis and insulin resistance in vitro

Steatosis is characterized by fat accumulation and insulin resistance (IR) in hepatocytes, which triggers a pro-oxidant, pro-inflammatory environment that may eventually lead to cirrhosis or liver carcinoma. This work was aimed to assess the effect of Sechium edule root hydroalcoholic extract (rSe-HA) (rich in cinnamic and coumaric acid, among other phenolic compounds) on triglyceride esterification, lipid degradation, AMPK expression, and the phosphorylation of insulin receptor in a Ser312 residue, as well as on the redox status, malondialdehyde (MDA) production, and the production of proinflammatory cytokines in an in vitro model of steatosis induced by oleic acid, to help develop a phytomedicine that could reverse this pathology. rSe-HA reduced triglyceride levels in hepatocyte lysates, increased lipolysis by activating AMPK at Thr172, and improved the redox status, as evidenced by the concentration of glycerol and formazan, respectively. It also prevented insulin resistance (IR), as measured by glucose consumption and the phosphorylation of the insulin receptor at Ser312. It also prevented TNFα and IL6 production and decreased the levels of MDA and nitric oxide (ON). Our results indicate that rSe-HA reversed steatosis and controlled the proinflammatory and prooxidant environment in oleic acid-induced dysfunctional HepG2 hepatocytes, supporting its potential use to control this disorder.

MODERN VIEWS ON THE PATHOGENESIS OF IMMUNE DYSFUNCTION AGAINST THE BACKGROUND OF THE METABOLIC SYNDROME IN ISCHEMIC HEART DISEASE

Introduction. Today, the pathology of the cardiovascular system is one of the most common and fatal diseases. Cardiovascular diseases are the cause of disability among the younger and younger population. Taking into account the frequency of cardiovascular diseases, the severity of the course and their lethality, the study of this topic remains one of the most urgent problems of medicine, in particular cardiology.
 The aim of the study. Consider modern views on the pathogenesis of coronary heart disease against the background of metabolic syndrome and the role of the immune system.
 Conclusions. Ischemic heart disease is the leading cause of mortality in Ukraine and the world. In recent years, there has been convincing evidence of a significant prevalence of cardiovascular disease in patients with metabolic syndrome. The presence of concomitant metabolic syndrome in patients with coronary heart disease worsens the course of the underlying disease and has an unfavorable prognosis, and even fatal cases.
 Therefore, the detection of an increase in the level of body mass index, dyslipidemia, hyperglycemia, arterial hypertension in a patient strengthens the effects of each other, that is, they have a synergistic effect, and in general, the risk of developing CHD becomes quite high.
 IL-6 is one of the cytokines released by both macrophages and adipocytes and its levels have been shown to be increased in insulin resistance and obesity. In fact, IL-6 is known to regulate fat and glucose metabolism, mediating insulin resistance through various complex mechanisms. This cytokine acts on various tissues, leading to the metabolic effects of obesity. In the liver, IL-6 increases the production of acute phase reactants, including CRP. Several studies have demonstrated that high CRP levels have the strongest correlation with cardiac events, T2DM, and MS. IL-6 also contributes to a prothrombotic state by increasing the level of fibrinogen, another acute phase reactant. In addition, IL-6 targets other tissues, such as endothelial cells, to promote the expression of vascular cell adhesion molecules, leading to vascular wall atherosclerosis, inflammation, and dysfunction.
 These data support the role of IL-6 in the development of insulin resistance, but do not support the hypothesis that IL-6 is involved in β-cell failure.
 IL-18 is a pro-inflammatory cytokine associated with insulin resistance and T2DM risk. IL-18 stimulates the production of gamma interferon (IFN-γ), which, in turn, is probably involved in the pathogenesis of atherosclerosis. IL-18 is a cytokine that is a predictor of metabolic syndrome.
 TNFα is another cytokine produced in adipose tissue, mainly from local macrophages, and its production also varies with adipose tissue mass and correlates with insulin resistance, both hallmarks of MS. TNFα exerts its pathogenic effects by disrupting insulin signaling in adipocytes and hepatocytes through serine phosphorylation and inactivation of insulin receptors and downstream signaling molecules, leading to decreased metabolic effects of insulin. TNFα also contributes to insulin resistance by inducing hepatic lipolysis.

Wheat germ peptide improves glucose metabolism and insulin resistance in HepG2 hepatocytes via regulating SOCS3/IRS1/Akt pathway

Evidence has demonstrated that oxidative stress plays a crucial role in regulating cellular glucose metabolism. In previous studies, wheat germ peptide (WGP) was found to effectively mitigate oxidative stress induced by high glucose. Based on the information provided, we hypothesized that WGP could exhibit antihyperglycemic and anti–insulin-resistant effects in cells. The insulin-resistant cell model was established by insulin stimulation. The glucose consumption, glycogen content, and the activities of hexokinase and pyruvate kinase following WGP treatment were measured. The protein expression of SOCS3, phosphorylated insulin receptor substrate-1 (p-IRS1), IRS1, phosphorylated protein kinase B (p-Akt), Akt, glucose transporter 2 (GLUT2), phosphorylated GSK 3β, GSK 3β, FOXO1, G6P, and phosphoenolpyruvate carboxykinase were assessed by western blot analysis. Our results demonstrated that WGP treatment increased cellular glucose consumption and glycogen synthesis and enhanced hexokinase and pyruvate kinase activities. Additionally, WGP treatment was observed to cause a significant reduction in the expression of SOCS3, FOXO1, G6P, and phosphoenolpyruvate carboxykinase, as well as in the ratio of p-IRS1/IRS1. Conversely, the expression of GLUT2 and the ratios of p-Akt/Akt and p-GSK3β/GSK3β were upregulated by WGP. These findings suggested that WGP can activate the SOCS3/IRS1/Akt signaling pathway, thus promoting the phosphorylation of GSK-3β and increasing the expression of FOXO1 and GLUT2, which contribute to enhancing glycogen synthesis, inhibiting gluconeogenesis, and promoting glucose transport in insulin-resistant HepG2 cells.

A Propolis-Derived Small Molecule Tectochrysin Ameliorates Type 2 Diabetes in Mice by Activating Insulin Receptor β.

Propolis has been found to decrease glucose levels and increase insulin sensitivity in type 2 diabetes. However, the active ingredient responsible for these effects and its regulating mechanism are not fully understood. To address this, molecular docking screening is used to screen the effective hypoglycemic ingredient in propolis and found that tectochrysin (TEC) has a high affinity to the insulin receptor (IR), highlighting its potential for glycemic control. In vivo tests show that TEC decreases glucose levels and enhances insulin sensitivity in db/db mice. By hyperinsulinemic euglycemic clamp test, this study further finds that TEC promotes glucose uptake in adipose tissue and skeletal muscle, as well as inhibits hepatic gluconeogenesis. Moreover, it finds that TEC promotes glucose uptake and adipocytes differentiation in 3T3-L1 cells like insulin, suggesting that TEC exerts an insulin mimetic effect. Mechanistically, pharmacology inhibition of IRβ abolishes the effects of TEC on glucose uptake and the phosphorylation of IR. The study further demonstrates that TEC binds to and activates IRβ by targeting its E1077 and M1079. Therefore, this study sheds light on the mechanism underlying propolis' potential for ameliorating type 2 diabetes, offering a natural food-derived compound as a promising therapeutic option.

ZFYVE28 mediates insulin resistance by promoting phosphorylated insulin receptor degradation via increasing late endosomes production

Insulin resistance is associated with many pathological conditions, and an in-depth understanding of the mechanisms involved is necessary to improve insulin sensitivity. Here, we show that ZFYVE28 expression is decreased in insulin-sensitive obese individuals but increased in insulin-resistant individuals. Insulin signaling inhibits ZFYVE28 expression by inhibiting NOTCH1 via the RAS/ERK pathway, whereas ZFYVE28 expression is elevated due to impaired insulin signaling in insulin resistance. While Zfyve28 overexpression impairs insulin sensitivity and causes lipid accumulation, Zfyve28 knockout in mice can significantly improve insulin sensitivity and other indicators associated with insulin resistance. Mechanistically, ZFYVE28 colocalizes with early endosomes via the FYVE domain, which inhibits the generation of recycling endosomes but promotes the conversion of early to late endosomes, ultimately promoting phosphorylated insulin receptor degradation. This effect disappears with deletion of the FYVE domain. Overall, in this study, we reveal that ZFYVE28 is involved in insulin resistance by promoting phosphorylated insulin receptor degradation, and ZFYVE28 may be a potential therapeutic target to improve insulin sensitivity.

Arsenic-induced IGF-1 signaling impairment and neurite shortening: The protective roles of IGF-1 through the PI3K/Akt axis.

We recently reported that arsenic caused insulin resistance in differentiated human neuroblastoma SH-SY5Y cells. Herein, we further investigated the effects of sodium arsenite on IGF-1 signaling, which shares downstream signaling with insulin. A time-course experiment revealed that sodium arsenite began to decrease IGF-1-stimulated Akt phosphorylation on Day 3 after treatment, indicating that prolonged sodium arsenite treatment disrupted the neuronal IGF-1 response. Additionally, sodium arsenite decreased IGF-1-stimulated tyrosine phosphorylation of the IGF-1 receptor β (IGF-1Rβ) and its downstream target, insulin receptor substrate 1 (IRS1). These results suggested that sodium arsenite impaired the intrinsic tyrosine kinase activity of IGF-1Rβ, ultimately resulting in a reduction in tyrosine-phosphorylated IRS1. Sodium arsenite also reduced IGF-1 stimulated tyrosine phosphorylation of insulin receptor β (IRβ), indicating the potential inhibition of IGF-1R/IR crosstalk by sodium arsenite. Interestingly, sodium arsenite also induced neurite shortening at the same concentrations that caused IGF-1 signaling impairment. A 24-h IGF-1 treatment partially rescued neurite shortening caused by sodium arsenite. Moreover, the reduction in Akt phosphorylation by sodium arsenite was attenuated by IGF-1. Inhibition of PI3K/Akt by LY294002 diminished the protective effects of IGF-1 against sodium arsenite-induced neurite retraction. Together, our findings suggested that sodium arsenite-impaired IGF-1 signaling, leading to neurite shortening through IGF-1/PI3K/Akt.

Exploration of the main active metabolites from Tinospora crispa (L.) Hook. f. & Thomson stem as insulin sensitizer in L6.C11 skeletal muscle cell by integrating in vitro, metabolomics, and molecular docking

Ethnopharmacological relevanceTinospora crispa (L.) Hook. f. & Thomson stem (TCS) has long been used as folk medicine for the treatment of diabetes mellitus. Previous study revealed that TCS possesses multi-ingredients and multi-targets characteristic potential as insulin sensitizer activity. However, its mechanisms of action and molecular targets are still obscure. Aim of the studyIn the present study, we investigated the effects of TCS against insulin resistance in muscle cells through integrating in vitro experiment and identifying its active biomarker using metabolomics and in molecular docking validation. Materials and methodsWe used centrifugal partition chromatography (CPC) to isolate 33 fractions from methanolic extract of TCS, and then used UHPLC-Orbitrap-HRMS to identify the detectable metabolites in each fraction. We assessed the insulin sensitization activity of each fraction using enzyme-linked immunosorbent assay (ELISA), and then used confocal immunocytochemistry microscopy to measure the translocation of glucose transporter 4 (GLUT4) to the cell membrane. The identified active metabolites were further simulated for its molecular docking interaction using Autodock Tools. ResultsThe polar fractions of TCS significantly increased insulin sensitivity, as measured by the inhibition of phosphorylated insulin receptor substrate-1 (pIRS1) at serine-312 residue (ser312) also the increasing number of translocated GLUT4 and glycogen content. We identified 58 metabolites of TCS, including glycosides, flavonoids, alkaloids, coumarins, and nucleotides groups. The metabolomics and molecular docking simulations showed the presence of minor metabolites consisting of tinoscorside D, higenamine, and tinoscorside A as the active compounds. ConclusionsOur findings suggest that TCS is a promising new treatment for insulin resistance and the identification of the active metabolites in TCS could lead to the development of new drugs therapies for diabetes that target these pathways.

Butyrate acts as a G-protein-coupled receptor ligand that prevents high glucose-induced amyloidogenesis in N2a cells through the protein kinase B/glycogen synthase kinase-3β pathway.

Butyrate acts as a G-protein-coupled receptor ligand that prevents high glucose-induced amyloidogenesis in N2a cells through the protein kinase B/glycogen synthase kinase-3β pathway.

METTL3 exacerbates insulin resistance in hepatocytes by regulating m6A modification of cytochrome P450 2B6

BackgroundInsulin resistance (IR) in hepatocytes endangers human health, and frequently results in the development of non-alcoholic fatty liver disease (NAFLD). Research on m6A methylation of RNA molecules has gained popularity in recent years; however, the molecular mechanisms regulating the processes of m6A modification and IR are not known. The cytochrome P450 (CYP450) enzyme system, which is mainly found in the liver, is associated with the pathogenesis of NAFLD. However, few studies have been conducted on CYP450 related m6A methylation. Here, we investigated the role of the methyltransferase METTL3 in exacerbating IR in hepatocytes, mainly focusing on the regulation of m6A modifications in CYP2B6.Methods and resultsAnalysis using dot blot and epitranscriptomic chips revealed that the m6A modification pattern of the transcriptome in high-fat diet (HFD)-induced fatty liver and free fatty acid (FFA)-induced fatty hepatocytes showed significant changes. CYP450 family members, especially Cyp2b10, whose homolog in humans is CYP2B6, led to a noticeable increase in m6A levels in HFD-induced mice livers. Application of the METTL3 methyltransferase inhibitor, STM2457, increased the level of insulin sensitivity in hepatocytes. We then analyzed the role of METTL3 in regulating m6A modification of CYP2B6 in hepatocytes. METTL3 regulated the m6A modification of CYP2B6, and a positive correlation was found between the levels of CYP2B6 translation and m6A modifications. Furthermore, interference with METTL3 expression and exposure to STM2457 inhibited METTL3 activity, which in turn interfered with the phosphorylated insulin receptor substrate (pIRS)-glucose transporter 2 (GLUT2) insulin signaling pathway; overexpression of CYP2B6 hindered IRS phosphorylation and translocation of GLUT2 to membranes, which ultimately exacerbated IR.ConclusionThese findings offer unique insights into the role that METTL3-mediated m6A modifications of CYP2B6 play in regulating insulin sensitivity in hepatocytes and provide key information for the development of strategies to induce m6A modifications for the clinical treatment of NAFLD.

Pigment Epithelium-Derived Factor: Inhibition of Phosphorylation of Insulin Receptor (IR)/IR Substrate (IRS), Osteogeneration from Adipocytes, and Increased Levels Due to Doxorubicin Exposure.

Pigment epithelium-derived factor (PEDF) has been recently linked to insulin resistance and is capable of differentiating myocytes to bone. We examined in more detail the intricate signalling of the insulin pathway influenced by PEDF in skeletal myocytes. We tested whether this serpin is also capable of generating de novo bone from adipocytes in vitro and in vivo, and how the anticancer drug doxorubicin links with PEDF and cellular metabolism. We demonstrate that PEDF can inhibit phosphorylation of insulin receptor (IR) and insulin receptor substrate (IRS) in skeletal myocytes. PEDF constitutively activates p42/44 MAPK/Erk, but paradoxically does not affect mitogenic signalling. PEDF did not perturb either mitochondrial activity or proliferation in cells representing mesenchymal stem cells, cardiomyocytes, and skeletal myocytes and adipocytes. PEDF induced transdifferentiation of adipocytes to osteoblasts, promoting bone formation in cultured adipocytes in vitro and gelfoam fatpad implants in vivo. Bone formation in white adipose tissue (WAT) was better than in brown adipose tissue (BAT). The frontline anticancer drug doxorubicin increased levels of PEDF in a human breast cancer cell line, mirroring the in vivo finding where cardiac muscle tissue was stained increasingly for PEDF as the dose of doxorubicin increased in mice. PEDF also increased levels of reactive oxygen species (ROS) and glutathione (GSH) in the breast cancer cell line. PEDF may be used to regenerate bone from adipose tissue in cases of trauma such as fractures or bone cancers. The increased presence of PEDF in doxorubicin-treated tumour cells need further exploration, and could be useful therapeutically in future. The safety of PEDF administration in vivo was further demonstrated in this study.

Effect of insulin on bone formation ability of rat alveolar bone marrow mesenchymal stem cells.

The alveolar bone marrow mesenchymal stem cells (ABM-MSCs) play an important role in oral bone healing and regeneration. Insulin is considered to improve impaired oral bones due to local factors, systemic factors and pathological conditions. However, the effect of insulin on bone formation ability of ABM-MSCs still needs to be elucidated. The aim of this study was to determine the responsiveness of rat ABM-MSCs to insulin and to explore the underlying mechanism. We found that insulin promoted ABM-MSCs proliferation in a concentration-dependent manner, in which 10-6 M insulin exerted the most significant effect. 10-6 M insulin significantly promoted the type I collagen (COL-1) synthesis, alkaline phosphatase (ALP) activity, osteocalcin (OCN) expression and mineralized matrix formation in ABM-MSCs, significantly enhanced the gene and protein expressions of intracellular COL-1, ALP and OCN. Acute insulin stimulation significantly promoted insulin receptor (IR) phosphorylation, insulin receptor substrate-1 (IRS-1) protein expression and mammalian target of rapamycin (mTOR) phosphorylation, but chronic insulin stimulation decreased these values, while inhibitor NT219 could attenuate these responses. When seeded on β-tricalcium phosphate (β-TCP), ABM-MSCs adhered and grew well, during the 28-day culture period, ABM-MSCs+β-TCP+10-6 M Insulin group showed significantly higher extracellular type I collagen amino-terminus prolongation peptide (TPINP) content, ALP activity, OCN secretion, Ca and P concentration. When implanted subcutaneously in severe combined immunodeficient mice for 1 month, the ABM-MSCs+β-TCP+10-6 M Insulin group obtained the most bone formation and blood vessels. These results showed that insulin promoted the proliferation and osteogenic differentiation of ABM-MSCs in vitro, and enhance osteogenesis and angiogenesis of ABM-MSCs in vivo. Inhibition studies demonstrated that the insulin-induced osteogenic differentiation of ABM-MSCs was dependent of insulin/mTOR signaling. It suggests that insulin has a direct anabolic effect on ABM-MSCs.

190-OR: Lrtm1, a Novel Regulator of Insulin Signaling and Metabolism

Patients with obesity and metabolic syndrome, as well as individuals with pre-type 2 diabetes, exhibit hyperinsulinemia prior to development of hyperglycemia due to underlying skeletal muscle insulin resistance. To mimic the effect of chronic hyperstimulation of the insulin receptor (IR), we overexpressed the IR specifically in skeletal muscle (IRMOE). This led to skeletal muscle post-receptor desensitization, with increased IR and IRS-1(Tyr) phosphorylation but decreased phosphorylation of Akt Ser473 and Thr308. To identify the regulators involved in this post-receptor insulin resistance, we performed RNA sequencing of IRMOE muscle. Among the most upregulated genes was Lrtm1, a poorly characterized leucine rich repeat transmembrane molecule while highly expressed in the heart and skeletal muscle. Overexpression of Lrtm1 in C2C12 myoblasts led to increased phosphorylation of early insulin signaling molecules (the insulin receptor, IRS-1, and Shc), but reduced phosphorylation of the downstream molecules Akt (at both Ser473 and Thr308) and Erk Thr202/204 following insulin stimulation. Mice with knockout of Lrtm1 (Lrtm1KO) showed significant increases in percent lean mass and decreases in percent fat mass, as well as a slight reduction in overall body weight. In addition, Lrtm1KO mice were more active than controls in both metabolic cages and an open field behavioral tests. Lrtm1KO mice also exhibited improved glucose tolerance and insulin sensitivity, especially in males, even on normal chow diet. Most importantly, Lrtm1KO mice were protected from high fat diet induced obesity and metabolic syndrome, with the knockouts showing 18% less body weight gain, 30% lower fat mass, significantly improved glucose tolerance and improved insulin sensitivity. Thus, Lrtm1 is a novel regulator of post-receptor insulin signaling and glucose metabolism that may provide a new target for therapy insulin resistant prediabetes and type 2 diabetes. Disclosure G. Wang: Employee; Agilent. Y. Yu: None. W. Chen: None. W. Cai: None. X. Liu: None. C. Kahn: None.

In Vitro Biological Characterization of Recombinant Insulin Aspart from Biogenomics and Originator Insulin Aspart.

Bioassays are used to identify the pharmacological activity of new or chemically unknown compounds, as well as their undesirable effect, including toxicity. Biological assays are also required to ensure the quality, safety, and efficacy of recombinant biologics to confirm its biosimilarity to its originator. In the present study, analytical similarity between the biosimilar and its innovator is established by in vitro bioassays. The objective of this study was to show the comparative in vitro characterization of the recombinant insulin aspart from BioGenomics with its originator insulin aspart, using relevant biological assays. In vitro assays such as receptor binding, receptor autophosphorylation, glucose uptake, and mitogenic potential were analyzed for biological characterization of BioGenomics recombinant insulin aspart (BGL-ASP) manufactured by BioGenomics Limited and NovoRapid® as the reference medicinal product (RMP) manufactured by NovoNordisk. Insulin receptor binding was studied by a state-of-the-art method, surface plasmon resonance (SPR) for biomolecular interactions. The receptor autophosphorylation assay measures the phosphorylated insulin receptor in cell lysates. The glucose uptake assay measures the uptake of glucose by 3T3-L1 cells in the presence of insulin. Lipogenesis was studied in treated 3T3-L1 cells by detecting the accumulation of lipid droplets in the cells. Mitogenic effect was studied by cell proliferation assay using MCF-7 cells. A rabbit bioidentity test was performed by measuring the sudden decrease in blood glucose in the presence of insulin. The binding studies showed thatthe affinity of BGL-ASP was highly comparable to NovoRapid®. Insulin receptor autophosphorylation, glucose uptake, and lipogenesis demonstrated high similarity to the RMP. The mitogenic assay for BGL-ASP did not show any proliferative effect and was comparable to the RMP. The in vivo bioidentity test showed that the BGL-ASP is highly similar to the innovator, NovoRapid®. The biological characterization studies of BGL-ASP demonstrated high binding and functional similarity to NovoRapid®.

Physicochemical and Functional Characterization of Medicinal Product Rinsulin® R

Introduction. Currently, biosimilars have found quite widespread use in the treatment of a number of chronic and life-threatening diseases. Thanks to them, there is a significant decrease of the economic pressure of biological drugs on the health care system and wide access of patients to effective and safe medicines is ensured. One of the most important stages of proving biosimilarity is the physicochemical and functional characterization of proteins. This set of studies is generally accepted, as sensitive as possible and allows us to give a conclusion about the compliance of the biosimilar with the original drug.Aim. Conducting physicochemical and functional characterization of medicinal product Rinsulin® R (GP40051) in comparison with the original drug Humulin® Regular.Materials and methods. Primary structure was analyzed by high-performance liquid chromatography with mass spectrometry detection and matrix assisted laser desorption/ionization. The identity of the higher protein structures was proved by the methods of circular dichroism, capillary isoelectric focusing, spectrometry and dynamic light scattering. The comparability of the impurity profiles of the preparations was evaluated using the methods of exclusive chromatography and reverse-phase high-performance liquid chromatography. Functional characterization included a metabolic cell test "glucose uptake" and insulin receptor–binding assay (kinetics of binding to type A and B receptors, phosphorylation of insulin receptor).Results and discussion. In the course of this research, the identity of the physicochemical and functional characteristics of GP40051 was shown. A complete overlap of primary sequence, high-order structures and impurity profiles was demonstrated between the comparison drug GP40051 and the reference drug Humulin® Regular. Functional studies have shown that GP40051 and Humulin® Regulars have the same activity.Conclusion. The results of the quality comparability study demonstrated similarity of Rinsulin® R to the reference medicinal product Humulin® Regular, providing the scientific basis for conducting a specifically designed clinical programme, and supported registration in Russian Federation.