scholarly journals Dioleoylphosphoethanolamine Retains Cell Surface GLUT4 by Inhibiting PKCα-Driven Internalization

2018 ◽  
Vol 46 (5) ◽  
pp. 1985-1998 ◽  
Author(s):  
Tomoyuki Nishizaki
Keyword(s):  
Cell Surface ◽  
Glucose Uptake ◽  
Glucose Transporter ◽  
Glucose Levels ◽  
Blood Glucose Levels ◽  
Surface Localization ◽  
Cell Surface Localization ◽  
Glucose Transporter Glut4

Background/Aims: Phosphatidylethanolamine, a component of the plasma membrane, regulates diverse cellular processes. The present study investigated the role of 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE) in the trafficking of the glucose transporter GLUT4 and the glucose homeostasis. Methods: Monitoring of GLUT4 trafficking, GLUT4 internalization assay, and glucose uptake assay were carried out using differentiated 3T3-L1-GLUT4myc adipocytes. Akt1/2 and PKC isozymes were knocked-down by transfecting each siRNA. Cell-free PKC assay and in situ PKCα assay with a FRET probe were carried out. Oral glucose tolerance test (OGTT) was performed using BKS.Cg-+Lepdb/+Lebdb/Jcl mice, an animal model of type 2 diabetes mellitus (DM). Results: DOPE increased cell surface localization of the glucose transporter GLUT4 in differentiated 3T3-L1-GLUT4myc adipocytes, regardless of Akt activation. Likewise, PKCα deficiency increased cell surface localization of GLUT4, that occludes the effect of DOPE. DOPE clearly suppressed phorbol 12-myristate 13-acetate-induced PKCα activation in the cell-free and in situ PKC assay. DOPE and PKCα deficiency cancelled endocytic internalization of GLUT4 localized on the plasma membrane after insulin stimulation. DOPE significantly enhanced glucose uptake into cells. A similar effect was obtained by knocking-down PKCα, that occludes the effect of DOPE. In OGTT, oral administration with DOPE effectively restricted an increase in the blood glucose levels after glucose loading in type 2 DM model mice. Conclusion: The results of the present study show that DOPE retains cell surface GLUT4 by suppressing PKCα-driven endocytic internalization of GLUT4, to enhance glucose uptake into cells and restrict an increase in the blood glucose levels after glucose loading in type 2 DM.

scholarly journals Glucose transporter inhibitor-conjugated insulin mitigates hypoglycemia

2019 ◽  
Vol 116 (22) ◽  
pp. 10744-10748 ◽  
Author(s):  
Jinqiang Wang ◽  
Jicheng Yu ◽  
Yuqi Zhang ◽  
Anna R. Kahkoska ◽  
Zejun Wang ◽  
...  
Keyword(s):  
Glucose Transporter ◽  
Diabetic Mouse ◽  
Insulin Analog ◽  
Glucose Levels ◽  
Blood Glucose Levels ◽  
Uncontrolled Diabetes ◽  
Increased Risk

Insulin therapy in the setting of type 1 and advanced type 2 diabetes is complicated by increased risk of hypoglycemia. This potentially fatal complication could be mitigated by a glucose-responsive insulin analog. We report an insulin-facilitated glucose transporter (Glut) inhibitor conjugate, in which the insulin molecule is rendered glucose-responsive via conjugation to an inhibitor of Glut. The binding affinity of this insulin analog to endogenous Glut is modulated by plasma and tissue glucose levels. In hyperglycemic conditions (e.g., uncontrolled diabetes or the postprandial state), the in situ-generated insulin analog−Glut complex is driven to dissociate, freeing the insulin analog and glucose-accessible Glut to restore normoglycemia. Upon overdose, enhanced binding of insulin analog to Glut suppresses the glucose transport activity of Glut to attenuate further uptake of glucose. We demonstrate the ability of this insulin conjugate to regulate blood glucose levels within a normal range while mitigating the risk of hypoglycemia in a type 1 diabetic mouse model.

scholarly journals An essential role for the Glut1 PDZ-binding motif in growth factor regulation of Glut1 degradation and trafficking

2009 ◽  
Vol 418 (2) ◽  
pp. 345-367 ◽  
Author(s):  
Heather L. Wieman ◽  
Sarah R. Horn ◽  
Sarah R. Jacobs ◽  
Brian J. Altman ◽  
Sally Kornbluth ◽  
...  
Keyword(s):  
Growth Factor ◽  
Cell Surface ◽  
Glucose Uptake ◽  
Pdz Domain ◽  
Binding Motif ◽  
Lysosomal Degradation ◽  
Interacting Protein ◽  
Surface Localization ◽  
Cell Surface Localization ◽  
Growth Factor Regulation

Cell surface localization of the Glut (glucose transporter), Glut1, is a cytokine-controlled process essential to support the metabolism and survival of haemopoietic cells. Molecular mechanisms that regulate Glut1 trafficking, however, are not certain. In the present study, we show that a C-terminal PDZ-binding motif in Glut1 is critical to promote maximal cytokine-stimulated Glut1 cell surface localization and prevent Glut1 lysosomal degradation in the absence of growth factor. Disruption of this PDZ-binding sequence through deletion or point mutation sharply decreased surface Glut1 levels and led to rapid targeting of internalized Glut1 to lysosomes for proteolysis, particularly in growth factor-deprived cells. The PDZ-domain protein, GIPC (Gα-interacting protein-interacting protein, C-terminus), bound to Glut1 in part via the Glut1 C-terminal PDZ-binding motif, and we found that GIPC deficiency decreased Glut1 surface levels and glucose uptake. Unlike the Glut1 degradation observed on mutation of the Glut1 PDZ-binding domain, however, GIPC deficiency resulted in accumulation of intracellular Glut1 in a pool distinct from the recycling pathway of the TfR (transferrin receptor). Blockade of Glut1 lysosomal targeting after growth factor withdrawal also led to intracellular accumulation of Glut1, a portion of which could be rapidly restored to the cell surface after growth factor stimulation. These results indicate that the C-terminal PDZ-binding motif of Glut1 plays a key role in growth factor regulation of glucose uptake by both allowing GIPC to promote Glut1 trafficking to the cell surface and protecting intracellular Glut1 from lysosomal degradation after growth factor withdrawal, thus allowing the potential for a rapid return of intracellular Glut1 to the cell surface on restimulation.

Ready, set, internalize: mechanisms and regulation of GLUT4 endocytosis

2008 ◽  
Vol 29 (1) ◽  
pp. 1-11 ◽  
Author(s):  
Costin N. Antonescu ◽  
Michelangelo Foti ◽  
Nathalie Sauvonnet ◽  
Amira Klip
Keyword(s):  
Insulin Resistance ◽  
Muscle Contraction ◽  
Glucose Uptake ◽  
Glucose Transporter ◽  
Muscle Cells ◽  
Fat Cells ◽  
Intracellular Membrane ◽  
Membrane Compartments ◽  
Glucose Transporter Glut4

The facilitative glucose transporter GLUT4, a recycling membrane protein, is required for dietary glucose uptake into muscle and fat cells. GLUT4 is also responsible for the increased glucose uptake by myofibres during muscle contraction. Defects in GLUT4 membrane traffic contribute to loss of insulin-stimulated glucose uptake in insulin resistance and Type 2 diabetes. Numerous studies have analysed the intracellular membrane compartments occupied by GLUT4 and the mechanisms by which insulin regulates GLUT4 exocytosis. However, until recently, GLUT4 internalization was less well understood. In the present paper, we review: (i) evidence supporting the co-existence of clathrin-dependent and independent GLUT4 internalization in adipocytes and muscle cells; (ii) the contrasting regulation of GLUT4 internalization by insulin in these cells; and (iii) evidence suggesting regulation of GLUT4 endocytosis in muscle cells by signals associated with muscle contraction.

scholarly journals Glycocalyx engineering with heparan sulfate mimetics attenuates Wnt activity during adipogenesis to promote glucose uptake and metabolism.

2021 ◽  
Author(s):  
Greg Trieger ◽  
Ariane Pessentheiner ◽  
Sean Purcell ◽  
Courtney R Green ◽  
Natalie DeForest ◽  
...  
Keyword(s):  
Heparan Sulfate ◽  
Glucose Uptake ◽  
Metabolic Phenotype ◽  
Peripheral Tissues ◽  
Insulin Resistant ◽  
Glucose Levels ◽  
Blood Glucose Levels ◽  
Glucose Clearance ◽  
Genetic Interventions

Adipose tissue (AT) plays a crucial role in maintaining metabolic homeostasis by storing lipids and glucose from circulation as intracellular fat. As peripheral tissues like AT become insulin resistant, decompensation of blood glucose levels occurs causing type 2 diabetes (T2D). Currently, glycocalyx modulating as a pharmacological treatment strategy to improve glucose homeostasis in T2D patients is underexplored. Here, we show a novel role for cell surface heparan sulfate (HS) in establishing glucose uptake capacity and metabolic utilization in differentiated adipocytes. Using a combination of chemical and genetic interventions, we identified that HS modulates this metabolic phenotype by attenuating levels of Wnt signaling during adipogenesis. By engineering the glycocalyx of preadipocytes with exogenous synthetic HS mimetics, we were able to enhance glucose clearance capacity after differentiation through modulation of Wnt ligand availability. These findings establish the cellular glycocalyx as a possible new target for therapeutic intervention in T2D patients by enhancing glucose clearance capacity independent of insulin secretion.

scholarly journals TORC2 inhibition of α-arrestin Aly3 effects cell surface persistence of S. pombe Ght5 glucose transporter in low-glucose

2021 ◽  
Author(s):  
Yusuke Toyoda ◽  
Saeko Soejima ◽  
Fumie Masuda ◽  
Shigeaki Saitoh
Keyword(s):  
Cell Surface ◽  
Molecular Mechanisms ◽  
Glucose Transporter ◽  
Gene Mutations ◽  
Gene Encoding ◽  
Glucose Depletion ◽  
Hexose Transporters ◽  
Surface Localization ◽  
Cell Surface Localization ◽  
Dependent Transport

In the fission yeast, Schizosaccharomyces pombe, the high-affinity hexose transporter, Ght5, must be transcriptionally upregulated and localized to the cell surface for cell division under limited glucose. While cell-surface localization of Ght5 depends on Target Of Rapamycin Complex 2 (TORC2), the molecular mechanisms by which TORC2 ensures proper localization of Ght5 remain unknown. We performed genetic screening for gene mutations that restore Ght5 localization on the cell surface in TORC2-deficient mutant cells, and identified a gene encoding an uncharacterized α-arrestin-like protein, Aly3/SPCC584.15c. α-arrestins are thought to recruit a ubiquitin ligase to membrane-associated proteins. Consistently, Ght5 is ubiquitinated in TORC2-deficient cells, and this ubiquitination is dependent on Aly3. TORC2 supposedly enables cell-surface localization of Ght5 by preventing Aly3-dependent ubiquitination and subsequent ubiquitination-dependent translocation of Ght5 to vacuoles. Surprisingly, nitrogen starvation, but not glucose depletion, triggers Aly3-dependent transport of Ght5 to vacuoles in S. pombe, unlike budding yeast hexose transporters, vacuolar transport of which is initiated upon changes in the hexose concentration. This study provides new insights into molecular mechanisms controlling subcellular localization of hexose transporters in response to extracellular stimuli.

Efeitos dos Programas de Treinamento Aeróbio, de Força e Combinado na Glicose Sanguínea em Diabéticos do Tipo 2: uma Revisão Sistemática/ Effects of Aerobic, Strength and Combined Programs Training on Blood Glucose in Type 2 Diabetic: a Systematic Review.

1970 ◽  
Vol 5 (1) ◽  
pp. 61-74 ◽  
Author(s):  
Alexandre de Souza E Silva ◽  
Maria Paula Gonçalves Mota
Keyword(s):  
Diabetes Mellitus ◽  
Systematic Review ◽  
Type 2 Diabetes ◽  
Blood Glucose ◽  
Training Program ◽  
Aerobic Training ◽  
Glucose Levels ◽  
Blood Glucose Levels ◽  
Pubmed Database

O trabalho tem como objetivo analisar os estudos que avaliaram os efeitos dos programas de treinamento aeróbio, força e combinado nos níveis de glicose sanguínea em indivíduos com diabetes do tipo 2. Foi utilizado o método de revisão sistemática, sendo utilizada a base de dados PubMed. As palavras chaves utilizadas para pesquisa foram training and diabetes. Foram identificados 484 artigos originais. Apenas 17 estudos respeitaram os critérios de inclusão. Os resultados evidenciam que os programas de treinamento aeróbio diminuíram os níveis de glicose. O programa de treinamento de força também foi favorável à diminuição dos níveis de glicose sanguínea. Já o programa de treinamento combinado não demonstrou efeitos favoráveis no controle da glicose sanguínea. Conclui-se que o programa de treinamento aeróbio e de força ajudam a controlar os níveis de glicose sanguínea em indivíduos com diabetes do tipo 2. Palavras-chave: diabetes mellitus, treinamento, glicose.ABSTRACTThe study aims to analyze the studies that evaluated the effects of aerobic, strength and combined programs training in blood glucose levels in people with type 2 diabetes. We used a systematic review method and is used to PubMed database. The key words used for searching were training and diabetes. We identified 484 original articles. Only 17 studies complied with the inclusion criteria. The results show that aerobic training programs decreased glucose levels. The strength training program was also favorable to decrease in blood glucose levels. But the combined training program has not shown favorable effects on blood glucose control. We conclude that the aerobic training and strength helps control blood glucose levels in individuals with type 2 diabetes. Keywords: diabetes mellitus, training, glucose.

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