Promotes Glucose Uptake Research Articles

Gremlin-1 activates Akt/STAT3 signaling, which increases the glycolysis rate in breast cancer cells

Gremlin-1 (GREM1), one of the antagonists of bone morphogenetic proteins (BMPs), has recently been reported to be overexpressed in a variety of cancers including breast cancer. GREM1 is involved in tumor promotion, but little is known about its role in the glycolysis of cancer cells. In this study, we investigated the role of GREM1 in glycolysis of breast cancer cells and its underlying molecular mechanisms. We first observed that glucose uptake and lactate production were increased in GREM1-overexpressing breast cancer cells. GREM1 increased the expression of hexokinase-2 (HK2), which catalyzes the phosphorylation of glucose, the first step in glycolysis. In addition, GREM1 activated STAT3 transcription factor through the ROS-Akt signaling pathway. The ROS-Akt-STAT3 axis activated by GREM1 was involved in promoting glucose uptake by increasing the expression of HK2 in breast cancer cells. Therefore, our study suggested a new mechanism by which GREM1 is involved in breast cancer promotion by increasing glycolysis in breast cancer cells.

Nicorandil Attenuates High Glucose-Induced Insulin Resistance by Suppressing Oxidative Stress-Mediated Endoplasmic Reticulum Stress Protein Kinase RNA-Like Endoplasmic Reticulum Kinase Singling Pathway

Background: Glucose- induced insulin resistance (IR) is a typical character of diabetes. Nicorandil is widely used in ischemic heart disease. Nicorandil shows protective effects against oxidative and endoplasmic reticulum (ER) stress which are involved in insulin resistance. Here we investigated mechanisms of nicorandil’s novel pharmacological activity on IR in diabetes. Methods: Nicorandil was administrated to diabetic animals and high-glucose exposed skeletal muscle cells. IR and glucose tolerance were evaluated. Molecular mechanisms concerning oxidative stress, ER stress and glucose uptake were assessed. Findings: Nicorandil attenuated high- glucose induced IR without affecting fasting blood glucose and glucose tolerance in whole body and skeletal muscle in diabetic rats. Nicorandil treatment suppressed protein kinase C(PKC)/ nicotinamide adenine dinucleotide phosphate (NADPH) oxidases (NOX) system activities by reducing cytoplasmic free calcium level in skeletal muscle cells exposed to high glucose. As a result, the oxidative stress- mediated ER stress protein kinase RNA- like endoplasmic reticulum kinase (PERK)/ eukaryotic initiation factor (EIF) 2α/ activating transcription factor (ATF)4/CEBP homologous protein (CHOP)/tribbles homolog (TRB)3 signaling pathway activation was inhibited. Nicorandil down-regulated expression of TRB3 and thus facilitated Akt phosphorylation in response to insulin stimulation, leading to glucose transporter (GLUT)4 plasma membrane translocation which promoted glucose uptake capability of skeletal muscle cells. Interpretation: By reducing cytoplasmic calcium, nicorandil alleviated high-glucose induced IR by inhibiting oxidative stress- mediated ER stress PERK pathway. This study indicated nicorandil as a promising agent in treatment of patients with ischemic heart disease complicated with diabetes. Funding Statement: This study was supported by Innovative Talents Promotion Project of Shaanxi Province (2019KJXX-019); Fundamental Scientific Research Foundation of Xi’an Jiaotong University (xzy012019131); Health Scientific Foundation of Shaanxi Province (2018E11); Natural Science Basic Research Foundation of Shaanxi Province (2020JQ-941). Declaration of Interests: The authors declare no conflicts of interest. Ethics Approval Statement: The experimental protocols were reviewed and approved by Institutional Animal Care and Use Committee of Medical Research Institute of Northwestern Polytechnical University.

SIRT1 deacetylates mitochondrial trifunctional enzyme \u03b1 subunit to inhibit ubiquitylation and decrease insulin resistance

Dysregulation of free acid metabolism is a major contributor to the development of insulin resistance and diabetes. Mitochondrial trifunctional enzyme subunit (MTPα) has a critical role in fatty acid β-oxidation. However, the association between MTPα and insulin resistance is not definitively known. Here, we aimed to determine how MTPα affects insulin resistance. We tested how MTPα affected glucose uptake in insulin-resistant 3T3-L1 adipocytes and white adipose tissue (WAT) of db/db diabetic mice. We also measured how acetylation and ubiquitylation modifications regulated MTPα activation and stability, using quantitative real-time polymerase chain reactions, immunoblotting, and immunoprecipitation. We found that MTPα overexpression promoted glucose uptake via Glut4 translocation to the plasma membrane in 3T3-L1 adipocytes. Moreover, MTPα upregulation decreased glycemia in db/db mice. Deacetylation increased MTPα protein stability and its ability to reduce insulin resistance. The activation of SIRT1, a major deacetylase, prevented MTPα degradation by decreasing its acetylation in adipocytes. Our study demonstrates a new role for MTPα in reducing insulin resistance. Acetylation and ubiquitylation modifications of MTPα were crucial to regulating its function in glucose metabolism.

Ovarian Cancer Cells Promote Glycolysis Metabolism and TLR8-Mediated Metabolic Control of Human CD4+ T Cells.

An immunosuppressive microenvironment is a major obstacle for successful tumor immunotherapy. Elucidating the regulatory mechanisms of energy metabolism and functionality in CD4+ T cells will provide insights for the development of novel immunotherapies for ovarian cancer (OC). An Agilent microarray was used to detect differences in gene expression between peripheral CD4+ T cells from five OC patients and those from five healthy controls. Functional pathway analysis was performed for differentially expressed genes. Gene expression profiles revealed significant differences in expression levels of 5,175 genes in peripheral CD4+ T cells from five patients with OC. Functional analysis indicated that the most significantly enriched pathways were metabolic pathways. Furthermore, eight glycolysis-related genes all showed significantly increased expression in peripheral CD4+ T cells of OC patients. Moreover, we established a coculture system of human CD4+ T cells with the OC cell line SKOV3, and then treated them with toll-like receptor 8 (TLR8) ligand ssRNA 40. Coculturing with SKOV3 cells could increase the expression of the eight glycolysis-related genes, promote glucose uptake and glycolysis in CD4+ T cells, induce the differentiation of CD4+ CD25+ Foxp3+ T cells, and enhance the suppression of naïve CD4+ T cells. Additionally, activated TLR8 signaling could mediate the reprogramming of glycolysis metabolism and function in CD4+ T cells. Overall, our study indicates that the SKOV3 coculture environment could regulate the glycolysis metabolism and function of CD4+ T cells, and also that TLR8 mediated the metabolic control of glycolysis in CD4+ T cells cocultured with SKOV3 cells. This provides a new direction for immunotherapy investigations in OC.

Caffeic acid improves glucose utilization and maintains tissue ultrastructural morphology while modulating metabolic activities implicated in neurodegenerative disorders in isolated rat brains.

Impaired glucose utilization has been implicated in the pathophysiology of neurodegenerative diseases. The neuroprotective effect of caffeic acid (CA) was investigated in the isolated rat brain by determining its ability to promote glucose uptake, mitigate redox imbalance, modulate purinergic and cholinergic activities, elemental distribution, and maintain tissue morphology. Isolated rat brains were incubated for 2 hours with glucose, CA and glucose, and metformin and glucose. There was an increased glucose uptake, glutathione level, superoxide dismutase, and catalase activities in brain tissues incubated with CA compared to the controls. Incubation with CA also led to significantly decreased levels of malondialdehyde, nitric oxide, acetylcholinesterase, butyrylcholinesterase, and ATPase activities. Electron microscopy (scanning electron microscopy and transmission electron microscopy) analysis portrayed a maintenance of tissue ultrastructural morphology in 2CA-incubated tissues as indicated by the intact synaptic vesicles, blood vessels, dendritic and neuronal network, mitochondria, and presynaptic membrane. CA also restored altered elemental levels in brain tissues. These results indicate the stimulatory potential of CA on brain glucose utilization with simultaneous neuroprotective activities.

Inhibition of lncRNA-UCA1 suppresses pituitary cancer cell growth and prolactin (PRL) secretion via attenuating glycolysis pathway.

Pituitary tumor is one type of endocrine tumor with high incidence and mortality rates. Long non-coding RNAs (lncRNAs) are a family of non-coding RNAs with longer than 200 nucleotides. Among them, lncRNA-UCA1 is highly expressed in multiple cancers and plays critically oncogenic roles in tumor progressions. However, the potential roles of UCA1 in human pituitary tumor have not been elucidated. In this study, the expressions of lncRNA-UCA1 were analyzed in thirty pituitary tumor samples and thirty normal pituitary tissues. Cancer cell glycolysis rate was examined by glucose uptake and lactate production. The lncRNA-UCA1 expression was detected by qRT-PCR. Glycolysis enzyme expressions were measured by Western blot and qRT-PCR. Consistent with other cancers, lncRNA-UCA1 was highly expressed in pituitary tumors. Meanwhile, we found glycolysis of pituitary tumors was higher than normal pituitary tissues. Overexpression of lncRNA-UCA1 in rat pituitary cancer cell lines, GH3 and MMQ, significantly promoted glucose uptake and lactate production. In addition, expressions of the glycolysis key enzymes, HK2 and LDHA, were significantly upregulated by exogenous overexpression of lncRNA-UCA1. Importantly, silencing lncRNA-UCA1 obviously inhibited pituitary cancer cells growth and prolactin (PRL) secretion. We report higher lncRNA-UCA1 expression is associated with higher serum PRL level in pituitary patients. Finally, by blocking the lncRNA-UCA1-promoted glycolysis of pituitary cancer cells by glycolysis inhibitor, 2-DG, we obtained recovery of cell growth rate and PRL secretion from an in vitro model. Taken together, our investigation revealed an oncogenic role of lncRNA-UCA1 through upregulating glycolysis of pituitary tumors. This study contributes to underlying molecular mechanisms of the tumorigenesis of pituitary tumors.

LncRNA SNHG10 increases the methylation of miR-218 gene to promote glucose uptake and cell proliferation in osteosarcoma

BackgroundThis study aimed to investigate the roles of lncRNA SNHG10 (SNHG10) and miR-218 in osteosarcoma (OS).MethodsPaired OS and non-tumor tissues were collected from 58 OS patients. The expression of SNHG10 and miR-218 in tissue samples were determined by RT-qPCR. The interaction between SNHG10 and miR-218 was evaluated by overexpression experiment. Methylation-specific PCR was performed to assess the methylation status of miR-218. Glucose uptake in OS cells was analyzed by glucose uptake assay. Cell proliferation was detected by cell proliferation assay.ResultsSNHG10 was upregulated in OS, while miR-218 was downregulated in OS. The expression of SNHG10 and miR-218 were inversely correlated. In OS cells, high glucose induced the upregulation of SNHG10 and downregulation of miR-218. In OS cells, SNHG10 positively, and miR-218 negatively regulated glucose uptake. Overexpression of SNHG10 increased miR-218 gene methylation and decreased the expression of miR-218. In addition, overexpression of SNHG10 also suppressed the inhibitory effects of overexpression of miR-218 on cell proliferation.ConclusionsSNHG10 increases the methylation of miR-218 gene to promote glucose uptake and cell proliferation in OS.

Abstract 3257: CTLA-4 blockade drives loss of regulatory T cell functional stability in glycolysis defective tumors

Abstract Only a limited fraction of patients derives durable clinical benefit upon immune checkpoint blockade. Deepening our understanding of mechanisms of response and resistance to these therapies is thus needed to optimize their employment in rational combinations. Cellular energy metabolism reprogramming is a critical hallmark of cancer. High glucose consumption and lactate production by tumor cells restrict nutrient availability in the tumor microenvironment (TME) for effector T cells, which also rely on glycolysis to replicate and function. In addition, immune checkpoints and co-stimulatory molecules are emerging as important regulators of T cell metabolism. Exploiting the capacity of immune checkpoint blockade to perturb T cell metabolism in combination with inhibition of tumor glycolysis may thus be a rational and more effective anti-cancer approach. We investigated the link between tumor glycolysis and immune cell function using RNA sequencing data sets from patients treated with checkpoint blockade and in tumor:T cell co-culture systems. We then studied the effects of checkpoint blockade in syngeneic glycolysis-defective murine tumor models and explored mechanisms underlying anti-tumor activity. We found that expression of glycolysis-related genes is inversely correlated with infiltration of most immune cell types in melanomas from patients before CTLA-4 blockade. However, after treatment, immune-related and glycolysis-related genes were more often co-expressed, suggesting that anti-CTLA-4 may partially restore immune cell fitness in the glycolytic TME. To directly assess the effect of tumor metabolism on T cell function, we co-cultured activated T cells with the highly glycolytic murine mammary carcinoma 4T1 and observed that tumor cells, or similar non-toxic concentrations of exogenous lactate, significantly limited T cell activation and viability. We thus investigated whether inhibition of tumor glycolysis could potentiate the activity of CTLA-4 blockade. We found that neoadjuvant treatment with anti-CTLA-4 significantly prolonged survival in mice bearing glycolysis defective 4T1 tumors, where lactate dehydrogenase A (LDH-A) - the critical enzyme controlling lactate production in aerobic glycolysis - was knocked down (4T1-KD). Intriguingly, tumor protection was associated with intratumoral regulatory T cell (Treg) functional phenotypic destabilization towards IFN-gamma and TNF-alpha producing Tregs. By mimicking the LDH-A-KD and control 4T1 TME in vitro using higher and lower concentrations of glucose, respectively, we showed that CTLA-4 blockade promotes glucose uptake by Tregs and more efficiently counteracts Treg suppression and enhances CD28 co-stimulation at higher glucose concentrations. These findings indicate that rebalancing glucose utilization in favor of immune cells in the TME may facilitate the activity of CTLA-4 blockade and reveal an additional mechanism through which anti-CTLA-4 interferes with Treg function in the presence of glucose. Citation Format: Roberta Zappasodi, Inna Serganova, Ivan Cohen, Masatomo Maeda, Masahiro Shindo, Yasin Senbabaoglu, Avigdor Leftin, Rachana Maniyar, Svena Verma, Matthew Lubin, Myat Kyaw Ko, Mayuresh M. Mane, Arnab Ghosh, Ellen Ackerstaff, Jason A. Koutcher, Ping-Chih Ho, Greg M. Delgoffe, Ronald Blasberg, Jedd D. Wolchok, Taha Merghoub. CTLA-4 blockade drives loss of regulatory T cell functional stability in glycolysis defective tumors [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 3257.

Signature of high altitude adaptation in the gluteus proteome of the yak

Yak is the unique Bovidae species in the Qinghai-Tibetan Plateau. A previous proteomic study has compared the yak muscle tissue to one cattle strain using the isobaric tags for relative and absolute quantification approach. In this study, to further investigate the molecular mechanisms underlying yak adaptation, the proteomic profiles of gluteus were compared between yak and one moderate-altitude cattle strain (Tibetan cattle) and two low-altitude cattle strains (Holstein and Sanjiang cattle) using a label-free quantitative method. The comparisons identified 20, 364, 143 upregulated proteins and 4, 6, 37 downregulated proteins in yak, compared with Tibetan, Holstein, and Sanjiang cattle, respectively. Protein-protein interaction analysis indicated that these differentially expressed proteinswere mainly related to "oxidative phosphorylation" and "electron transport chain."Further analysis revealed that NADH dehydrogenase [ubiquinone] 1 alpha subcomplex subunit 11, NADH dehydrogenase [ubiquinone] 1 beta subcomplex subunit 4, cytochrome C oxidase subunit 6A2, mitochondrialand cytochrome c oxidase subunit NDUFA4were all increased in the yak, suggesting that yak might increase mitochondrial capacity to sustain metabolic rates under high altitude conditions, which might be a long-term adaptive mechanism underlying adaptation to high altitude environments. Yak increased the level of thioredoxin reductase 2to protect themselves from oxidative damages. Moreover, the increased expression levels of phosphatidylinositol 4,5-bisphosphate 3-kinase catalytic subunit alpha isoformand caveolin-1 in yak suggested that yaks promoted glucose uptake for adaptation to high altitude. These results provided more information to better understand the molecular mechanisms underlying yak adaption.

Casein kinase 2 inhibitor CX-4945 elicits an anti-Warburg effects through the downregulation of TAp73 and inhibits gastric tumorigenesis

Casein kinase 2 (CK2) has become a potential therapeutic target in gastric cancer; however, the underlying mechanism remains incompletely understood. TAp73, a structural homolog of the tumor suppressor p53, acts as a critical regulator of the Warburg effect. Recent study reveals that aberrant CK2 signaling is able to inhibit TAp73 function. Here we determine that TAp73 is overexpressed in AGS-1 but not in SNU-5 gastric cancer cell line as compared with normal gastric cells. In addition, we show that TAp73 expression is required for the maintenance of glucose uptake and lactate release in AGS-1 but not in SNU-5 gastric cancer cells. Importantly, the use of CX-4945, a selective inhibitor of protein kinase CK2, inhibits cell growth and invasion, and promotes cell apoptosis in AGS-1 with decreased TAp73 expression as well as downregulated glucose uptake and lactate release. Although TAp73 knockdown resulted in significant decreases in TAp73 expressions in SNU-5 cell line, no differences in glucose uptake and lactate release were observed between SNU-5 and normal gastric cells. Moreover, TAp73 gene overexpression promotes glucose uptake and lactate release and abolishes the anti-cancer effects of CX-4945 in gastric cancer cell line AGS-1. The impacts of CX-4945 on glycolysis and tumorigenesis were strongly limited in SNU-5 gastric cancer cell line. These findings suggest that CX-4945 elicits an anti-Warburg effects in gastric cancer overexpressing Tap73 and inhibits gastric tumorigenesis.

Down-Regulated miR-21 in Gestational Diabetes Mellitus Placenta Induces PPAR-α to Inhibit Cell Proliferation and Infiltration.

PurposeThis study aimed to investigate the role of miR-21 expression in the reduction of placental function in GDM patients.Materials and MethodsqRT-PCR was used to detect the differential expression of miR-21 in the serum of gestational diabetes mellitus (GDM) and normal pregnant women, and to verify the functional target gene PPAR-α of miR-21 by double fluorescence experiments. Cellular experiments were performed to verify the effect of PPAR-α on cell function.ResultsmiR-21 is down-regulated in the serum and placenta of GDM patients compared to normal pregnant women. In the case of insulin resistance, miR-21-5p knockdown promoted glucose uptake, but no significant effect was found under physiological condition. Functional studies have shown that reduced PPAR-α expression can restore miR-21 knockdown-mediated cell growth and metastasis inhibition. Additionally, decreased expression of miR-21 but increased expression of -PPAR-α was observed in patients with GDM and GDM rats.ConclusionThe expression of the placental miR-21-5p, which inhibits cell growth and infiltration by up-regulating PPAR-α, is downregulated in pregnant GDM patients, which in turn may affect the placental function.

Comparison of anti-hyperglycemic activities between low- and high-degree of polymerization procyanidin fractions from cacao liquor extract

Procyanidins are thought to be effective for prevention of hyperglycemia. To clarify the degree of polymerization (DP) of procyanidins on anti-hyperglycemic effects, we prepared low-DP (DP ≤ 3) and high-DP (DP ≥ 4) procyanidin fractions from cacao liquor, and examined whether these procyanidin fractions prevent hyperglycemia in vitro. We found that both fractions promoted glucose uptake in L6 myotubes in a dose-dependent manner accompanied by translocation of GLUT4 to the plasma membrane. Moreover, both fractions stimulate phosphorylation of AMP-activated protein kinase (AMPK). In these beneficial effects, low-DP fraction was more effective than high-DP one. On the other hand, high-DP fraction showed greater inhibitory effect of intestinal α-glucosidase activity than low-DP fraction in a cell free-incubation system. In conclusion, cacao liquor procyanidins have anti-hyperglycemic activities and low-DP procyanidins mainly contribute to stimulate glucose uptake by glucose transporter 4 translocation through AMPK-dependent pathway in skeletal muscle while high-DP procyanidins mainly contributes to inhibit the α-glucosidase activity in small intestine.

IGFBP5 modulates lipid metabolism and insulin sensitivity through activating AMPK pathway in non-alcoholic fatty liver disease

AimsNon-alcoholic fatty liver disease (NAFLD) characterized by excessive hepatic fat deposition is an increasing public health issue worldwide. Insulin resistance is a pivotal factor in NAFLD progression. Studies have found that IGFBP5 was related to insulin sensitivity. Nevertheless, the role of IGFBP5 in NAFLD remains unclear. Materials and methodsNAFLD models were established in vitro and in vivo by treating HepG2 cells with free fatty acids (FFA) and feeding mice with high-fat diet (HFD), respectively. IGFBP5 expression was then analyzed in these models. The effects and mechanism of IGFBP5 on lipid lipogenesis, fatty acid β-oxidation, and insulin resistance were investigated following IGFBP5 overexpression. Additionally, AMPK inhibitor compound C was used to treat HepG2 cells to confirm whether IGFBP5 functioned via activating AMPK pathway. Key findingsIGFBP5 expression was decreased in both NAFLD models. IGFBP5 overexpression reduced levels of lipogenesis-associated proteins (SREBP-1c, FAS and ACC1), elevated expression of fatty acid β-oxidation-related genes (PPARα, CPT1A and ACOX1), decreased intracellular lipid droplets, promoted glucose uptake and glycogenesis, and activated IRS1/Akt and AMPK pathways. Administration of IGFBP5 vectors also decreased body weight and relieved liver damage in HFD-treated mice. In contrast, compound C abrogated the influences of IGFBP5 overexpression on cell models. SignificanceIGFBP5 dampened hepatic lipid accumulation and insulin resistance in NAFLD development via activating AMPK pathway. This study indicates that IGFBP5 may be a novel therapeutic agent for NAFLD.

Eliminating the capsule-like layer to promote glucose uptake for hyaluronan production by engineered Corynebacterium glutamicum

Hyaluronan is widely used in cosmetics and pharmaceutics. Development of robust and safe cell factories and cultivation approaches to efficiently produce hyaluronan is of many interests. Here, we describe the metabolic engineering of Corynebacterium glutamicum and application of a fermentation strategy to manufacture hyaluronan with different molecular weights. C. glutamicum is engineered by combinatorial overexpression of type I hyaluronan synthase, enzymes of intermediate metabolic pathways and attenuation of extracellular polysaccharide biosynthesis. The engineered strain produces 34.2 g L−1 hyaluronan in fed-batch cultures. We find secreted hyaluronan encapsulates C. glutamicum, changes its cell morphology and inhibits metabolism. Disruption of the encapsulation with leech hyaluronidase restores metabolism and leads to hyper hyaluronan productions of 74.1 g L−1. Meanwhile, the molecular weight of hyaluronan is also highly tunable. These results demonstrate combinatorial optimization of cell factories and the extracellular environment is efficacious and likely applicable for the production of other biopolymers.

MUC16 C-terminal binding with ALDOC disrupts the ability of ALDOC to sense glucose and promotes gallbladder carcinoma growth

The MUC16 C-terminal (MUC16c) level is associated with tumor serum CA-125 levels, however, the roles remain unclear in gallbladder carcinoma (GBC). In this study, we found that MUC16c promoted glucose uptake and glycolysis for GBC cell proliferation. Mass spectrometry analysis suggested that MUC16c could combine with aldolase. The ALDOC mRNA and protein are overexpressed in GBC tumors. The IHC results also showed the consistent up-regulation of.ALDOC and MUC16c level in GBC tumor tissues than in peritumor tissues. We determined that MUC16c combining with ALDOC promoted ALDOC protein stability and disrupted the ability of ALDOC sensing glucose deficiency, which activated AMPK pathway and increased GBC cell proliferation. ALDOC knockdown significantly inhibited the glucose uptake and glycolysis induced by MUC16c. Our study established important roles of MUC16c promoting GBC cell glycolysis and proliferation and revealed the underlying mechanism of CA-125-related heavy tumor metabolic burden in GBC.

1822-P: Regulation of Trafficking of Lipids from Liver to Fat by ApoA4 in a Mouse Model of Nonalcoholic Steatohepatitis

Lipogenesis and lipolysis largely determining adipose tissues and liver lipid content, and the imbalance between them contributes to fatty liver disease and metabolic syndromes. Lipogenesis and lipolysis are regulated by nutritional signals and metabolic hormones such as insulin through multiple mechanisms. Apolipoprotein A-IV (ApoA4), secreted largely by intestine, is existed as the composition of HDL and as the free form mostly in blood. ApoA4 plays the important roles in anti-atherosclerosis and lowering blood glucose. After we found its suppressing hepatic gluconeogenesis via NR1D1/NR4A1, and promoting glucose uptake in adipose tissues through PI3K-Akt-GLUT4, we have studied the action of ApoA4 on lipid metabolism with ApoA4 knock-out mice (A4KO). We found that ApoA4 deficiency resulted in worse fatty liver in diet induced obesity (DIO) mice. ApoA4 deficiency lowered the expression of hepatic ATGL, the rate-limiting enzyme for lipolysis, but enhanced the expression of key lipogenic enzymes such as ACC and SCD1. However, the expression of ATGL was increased and the expression of ACC, SCD1, FAS as well as their transcriptional activator SREBP1 were decreased from both BAT and WAT in A4KO mice. Furthermore, ApoA4 deletion also resulted in the inhibited expression of key proteins in thermogenesis pathway SIRT1, PGC1 and UCP1. Moreover, either overexpression of ApoA4 by delivery of AAV-ApoA4 or one time injection of ApoA4 protein resulted in reversed expression of key enzymes for lipogenesis and lipolysis both in liver and adipose tissues from A4KO DIO mice. These data suggest that ApoA4 may promote lipolysis in liver, but inhibited lipolysis and enhance lipogenesis and energy metabolism in adipose tissues, implying ApoA4’s action of regulating the trafficking of lipids from liver to fat and then turn fat into energy for burning. Disclosure X. Li: None. X. Liu: None. C. Cheng: None. J. Zhou: None. J. Fan: None. S. Li: None. Funding National Natural Science Foundation of China (81770798, 81700691)

296-OR: Identification and Characterization of New Players in Insulin-Controlled GLUT4 Trafficking

The anabolic hormone insulin promotes glucose uptake by triggering the translocation of the glucose transporter GLUT4 from intracellular storage vesicles to the cell surface through exocytosis. Upon the termination of insulin signaling, GLUT4 gradually returns to intracellular storage compartments through endocytosis. Defects in GLUT4 translocation are a hallmark of insulin resistance (IR) and type 2 diabetes (T2D). Our team has performed genome-scale genetic screens to systematically dissect GLUT4 exocytosis and endocytosis. The screens recovered known GLUT4 trafficking regulators but most of the hits were not previously linked to the GLUT4 pathway. A regulator of GLUT4 endocytosis identified in the screens is AAGAB, a soluble factor of 34 kDa. AAGAB controls the stepwise assembly of AP2 adaptor, a central cargo adaptor in clathrin-mediated endocytosis. Unexpectedly, we found that AAGAB also binds to Munc18c and directly inhibits SNARE-Munc18-mediated GLUT4 vesicle fusion. Thus, AAGAB plays a dual role in GLUT4 trafficking. I will also discuss OSBPL8 and OSBPL10, two negative regulators of GLUT4 translocation identified in our screens. OSBPL8 and OSBPL10 are putative lipid transfer proteins operating between intracellular organelles. We propose that OSBPL8 and OSBPL10 regulate lipid dynamics required for insulin signaling, thereby influencing the activities of GLUT4 exocytic regulators. These genetic studies will likely facilitate the identification of new therapeutic targets for IR and T2D. Disclosure J. Shen: None. Funding American Diabetes Association (1-19-IBS-305); National Institutes of Health (DK095367, GM126960)

Fibroblast Growth Factor 21 Signaling Activation by Selected Bioactive Compounds from Cocoa Shell Modulated Metabolism and Mitochondrial Function in Hepatocytes

Abstract Objectives To evaluate the effect of selected bioactive compounds from cocoa shell and its aqueous extract on the activation of fibroblast growth factor 21 (FGF21) signaling in hepatocytes and the resulting modulation of lipid and glucose metabolism, oxidative stress, and mitochondrial function. Methods The bioactive compounds from cocoa shells were extracted using water and characterized by UPLC-MS/MS. An in vitro model of non-alcoholic fatty liver disease was used: HepG2 cells were co-treated with either pure theobromine (TH), protocatechuic acid (PCA), procyanidin B2 (PB2), epicatechin (EPI), catechin (CAT) (10–50 µmol L−1), or the aqueous extract from cocoa shells (CAE, 20–100 µg mL−1) in the presence or absence of palmitic acid (PA, 500 µmol L−1). FGF21 receptor interaction with cocoa shell phytochemical was evaluated in silico. Biomarkers of cell metabolism were assessed 24 h after the co-treatment in cell supernatants and lysates using chemical, biochemical, and immunochemical techniques. Results Phytochemicals from cocoa shell were able to interact in silico with FGF21 receptor (biding energies from −6.0 to −11.0 kcal mol−1) denoting a potential interaction causing FGF21 receptor response. FGF21 hepatic signaling was activated (1.1 to 2.3-fold enhance in ERK1/2 phosphorylation). CAE, TH, PCA, PB2, EPI, and CAT diminished PA-elicited lipid accumulation (5–86%, P < 0.05) by reducing fatty acid synthase expression, and stimulated lipolysis (1–87%, P < 0.05) through the up-regulation of lipoprotein lipase expression. CAE and therein-bioactive compounds, mainly TH and PCA, promoted glucose uptake (4–35%, P < 0.05) via the increase in the phosphorylation of the insulin receptor (2.2-fold, P < 0.05), protein kinase B (2.8-fold, P < 0.05), AMPKα (2.0-fold, P < 0.05), and ERK1/2 (2.8-fold, P < 0.05) phosphorylation. Oxidative stress was prevented (50–100%, P < 0.05), and the loss of mitochondrial content (15–100%, P < 0.05) and function, measured as ATP production, alleviated (28–100%, P < 0.05). Conclusions Results demonstrated that the major bioactive compounds, primarily TH and PCA, found in cocoa shell could activate FGF21 signaling and regulated hepatic lipid and glucose metabolism, preventing insulin resistance, oxidative stress, and mitochondrial dysfunction. Funding Sources USDA-NIFA-HATCH, and the Spanish Ministry of Science and Innovation.

New insights into the in vitro, in situ and in vivo antihyperglycemic mechanisms of gallic acid and p-coumaric acid

Objective: To explore the probable in vitro, in situ and in vivo mechanisms of gallic acid (GA) and p-coumaric acid (PCA) as anti-hyperglycemic agents. Animals and methods: Male albino rats were allocated into four groups, group1 was used as normal control. Group 2 was established as a diabetic control and group3 and 4 were treated with an oral dose of GA and PCA, respectively. Results: GA and PCA revealed a significant decrease in the activity of α-amylase, a noticeable rise in glucose induced-insulin secretion and glucose-uptake in peripheral glucose-uptake in vitro, increase also liver glycogen and serum insulin levels in vivo. Further, GA and PCA exhibited a significant reduction in intestinal glucose absorption in situ compared to blank. Conclusion: The antihyperglycemic activities of GA and PCA can be mediated through delaying intestinal glucose absorption, enhancing β-cell activity and promoting glucose uptake by peripheral tissue via enhancing insulin sensitivity.

NF-κB inhibitor QNZ protects human chondrocyte degeneration by promoting glucose uptake through Glut4 activation.

Glucose is not only an energy source but also raw material for proteoglycan biosynthesis of chondrocyte. The aim of the present study is to explore the role of QNZ in the progress of chondrocytes glucose uptake and investigate whether it will improve the chondrocytes degeneration through Glut4 activation. We isolated human chondrocytes from the cartilage by the patients who underwent total knee arthroplasty operations. Chondrocytes were pretreated with insulin or QNZ for 24 h. The uptake of glucose with stimulation, as well as the expression of Glut4, collagen II, aggrecan, MMP13, TNF-α, PCNA, and the p16 levels were determined by Western blot, quantitative reverse-transcription polymerase chain reaction (qPCR), or immunofluorescence. Both insulin and QNZ stimuli to chondrocytes contributed to the expression of Glut4 and glucose uptake compared to the normal cells. Additionally, collagen II and aggrecan expression was detected to a significant increase, along with the reduced levels of MMP13 and TNF-α after exposed to QNZ. Moreover, QNZ protected chondrocytes degeneration via promoting proliferation and delaying aging. After blocking Glut4, the glucose uptake significantly reduced in QNZ treatment, as well as the expression of collagen II and aggrecan. However, no significant changes were noticed in the MMP13 and TNF-α levels. The present study demonstrates that inhibition of NF-κB activation by QNZ would improve the glucose uptake through Glut4 activation, which plays an important role in the protection of chondrocytes degeneration.