scholarly journals Knockout of glucose transporter GLUT6 has minimal effects on whole body metabolic physiology in mice

2018 ◽  
Vol 315 (2) ◽  
pp. E286-E293 ◽  
Author(s):  
Frances L. Byrne ◽  
Ellen M. Olzomer ◽  
Robert Brink ◽  
Kyle L. Hoehn
Keyword(s):  
Glucose Transporter ◽  
Gene Expression Pattern ◽  
Western Diet ◽  
Whole Body ◽  
Chow Diet ◽  
Mouse Development ◽  
Wild Type Littermate ◽  
Female Mice ◽  
Transporter Family ◽  
Metabolic Physiology

Glucose transporter 6 (GLUT6) is a member of the facilitative glucose transporter family. GLUT6 is upregulated in several cancers but is not widely expressed in normal tissues. Previous studies have shown that GLUT6 knockdown kills endometrial cancer cells that express elevated levels of the protein. However, whether GLUT6 represents a viable anticancer drug target is unclear because the role of GLUT6 in normal metabolic physiology is unknown. Herein we generated GLUT6 knockout mice to determine how loss of GLUT6 affected whole body glucose homeostasis and metabolic physiology. We found that the mouse GLUT6 ( Slc2a6) gene expression pattern was similar to humans with mRNA found primarily in brain and spleen. CRISPR-Cas9-mediated deletion of Slc2a6 did not alter mouse development, growth, or whole body glucose metabolism in male or female mice fed either a chow diet or Western diet. GLUT6 deletion did not impact glucose tolerance or blood glucose and insulin levels in male or female mice fed either diet. However, compared with wild-type littermate controls, GLUT6 null female mice had a relatively minor decrease in fat accumulation when fed Western diet and had a lower respiratory exchange ratio when fed chow diet. Collectively, these data show that GLUT6 is not a major regulator of whole body metabolic physiology; therefore, GLUT6 inhibition may have minimal adverse effects if targeted for cancer therapy.

scholarly journals Petite Integration Factor 1 (PIF1) helicase deficiency increases weight gain in Western diet-fed female mice without increased inflammatory markers or decreased glucose clearance

2018 ◽  
Author(s):  
Frances R. Belmonte ◽  
Nikolaos Dedousis ◽  
Ian Sipula ◽  
Nikita A. Desai ◽  
Aatur D. Singhi ◽  
...  
Keyword(s):  
Gene Expression ◽  
Weight Gain ◽  
Hepatic Steatosis ◽  
Inflammatory Markers ◽  
Western Diet ◽  
Metabolic Phenotype ◽  
Whole Body ◽  
Chow Diet ◽  
Female Mice ◽  
Glucose Clearance

AbstractPetite Integration Factor 1 (PIF1) is a multifunctional helicase present in nuclei and mitochondria. PIF1 knock out (KO) mice exhibit accelerated weight gain and decreased wheel running on a normal chow diet. In the current study, we investigated whether Pif1 removal alters whole body metabolism in response to weight gain. PIF1 KO and wild type (WT) C57BL/6J mice were fed a Western diet (WD) rich in fat and carbohydrates before evaluation of their metabolic phenotype. Compared with weight gain-resistant WT female mice, WD-fed PIF1 KO females, but not males, showed accelerated adipose deposition, decreased locomotor activity, and reduced whole-body energy expenditure without increased dietary intake. Surprisingly, PIF1 KO females were protected against obesity-induced alterations in fasting blood glucose and glucose clearance. WD-fed PIF1 KO females developed mild hepatic steatosis and associated changes in liver gene expression that were absent in weight-matched, WD-fed female controls, linking hepatic steatosis to Pif1 ablation rather than increased body weight. WD-fed PIF1 KO females also showed decreased gene expression of inflammatory markers in adipose tissue. Collectively, these data separated weight gain from inflammation and impaired glucose homeostasis. They also support a role for Pif1 in weight gain resistance and liver metabolic dysregulation during nutrient stress.

scholarly journals Endothelial Estrogen Receptor-α Does Not Protect Against Vascular Stiffness Induced by Western Diet in Female Mice

Endocrinology ◽  
2016 ◽  
Vol 157 (4) ◽  
pp. 1590-1600 ◽  
Author(s):  
Camila Manrique ◽  
Guido Lastra ◽  
Francisco I. Ramirez-Perez ◽  
Dominic Haertling ◽  
Vincent G. DeMarco ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Estrogen Receptor ◽  
Vascular Reactivity ◽  
Control Diet ◽  
Western Diet ◽  
Vascular Stiffness ◽  
Whole Body ◽  
Chow Diet ◽  
Female Mice ◽  
Vascular Stiffening

Abstract Consumption of a diet high in fat and refined carbohydrates (Western diet [WD]) is associated with obesity and insulin resistance, both major risk factors for cardiovascular disease (CVD). In women, obesity and insulin resistance abrogate the protection against CVD likely afforded by estrogen signaling through estrogen receptor (ER)α. Indeed, WD in females results in increased vascular stiffness, which is independently associated with CVD. We tested the hypothesis that loss of ERα signaling in the endothelium exacerbates WD-induced vascular stiffening in female mice. We used a novel model of endothelial cell (EC)-specific ERα knockout (EC-ERαKO), obtained after sequential crossing of the ERα double floxed mice and VE-Cadherin Cre-recombinase mice. Ten-week-old females, EC-ERαKO and aged-matched genopairs were fed either a regular chow diet (control diet) or WD for 8 weeks. Vascular stiffness was measured in vivo by pulse wave velocity and ex vivo in aortic explants by atomic force microscopy. In addition, vascular reactivity was assessed in isolated aortic rings. Initial characterization of the model fed a control diet did not reveal changes in whole-body insulin sensitivity, aortic vasoreactivity, or vascular stiffness in the EC-ERαKO mice. Interestingly, ablation of ERα in ECs reduced WD-induced vascular stiffness and improved endothelial-dependent dilation. In the setting of a WD, endothelial ERα signaling contributes to vascular stiffening in females. The precise mechanisms underlying the detrimental effects of endothelial ERα in the setting of a WD remain to be elucidated.

scholarly journals FABP4-Cre Mediated Expression of Constitutively Active ChREBP Protects Against Obesity, Fatty Liver, and Insulin Resistance

Endocrinology ◽  
2015 ◽  
Vol 156 (11) ◽  
pp. 4020-4032 ◽  
Author(s):  
Alli M. Nuotio-Antar ◽  
Naravat Poungvarin ◽  
Ming Li ◽  
Michael Schupp ◽  
Mahmoud Mohammad ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Adipose Tissue ◽  
Fatty Liver ◽  
Binding Protein ◽  
Western Diet ◽  
Whole Body ◽  
Lipid Homeostasis ◽  
Chow Diet ◽  
Fatty Acid Binding ◽  
Constitutively Active

Carbohydrate response element binding protein (ChREBP) regulates cellular glucose and lipid homeostasis. Although ChREBP is highly expressed in many key metabolic tissues, the role of ChREBP in most of those tissues and the consequent effects on whole-body glucose and lipid metabolism are not well understood. Therefore, we generated a transgenic mouse that overexpresses a constitutively active ChREBP isoform under the control of the fatty acid binding protein 4-Cre-driven promoter (FaChOX). Weight gain was blunted in male, but not female, FaChOX mice when placed on either a normal chow diet or an obesogenic Western diet. Respiratory exchange ratios were increased in Western diet-fed FaChOX mice, indicating a shift in whole-body substrate use favoring carbohydrate metabolism. Western diet-fed FaChOX mice showed improved insulin sensitivity and glucose tolerance in comparison with controls. Hepatic triglyceride content was reduced in Western diet-fed FaChOX mice in comparison with controls, suggesting protection from fatty liver. Epididymal adipose tissue exhibited differential expression of genes involved in differentiation, browning, metabolism, lipid homeostasis, and inflammation between Western diet-fed FaChOX mice and controls. Our findings support a role for ChREBP in modulating adipocyte differentiation and adipose tissue metabolism and inflammation as well as consequent risks for obesity and insulin resistance.

scholarly journals Hepatic steatosis, inflammation, and ER stress in mice maintained long term on a very low-carbohydrate ketogenic diet

2011 ◽  
Vol 300 (6) ◽  
pp. G956-G967 ◽  
Author(s):  
Joel R. Garbow ◽  
Jason M. Doherty ◽  
Rebecca C. Schugar ◽  
Sarah Travers ◽  
Mary L. Weber ◽  
...  
Keyword(s):  
Ketogenic Diet ◽  
Western Diet ◽  
Whole Body ◽  
Resonance Spectroscopy ◽  
Chow Diet ◽  
High Fat ◽  
Low Protein ◽  
Low Carbohydrate ◽  
Term Administration

Low-carbohydrate diets are used to manage obesity, seizure disorders, and malignancies of the central nervous system. These diets create a distinctive, but incompletely defined, cellular, molecular, and integrated metabolic state. Here, we determine the systemic and hepatic effects of long-term administration of a very low-carbohydrate, low-protein, and high-fat ketogenic diet, serially comparing these effects to a high-simple-carbohydrate, high-fat Western diet and a low-fat, polysaccharide-rich control chow diet in C57BL/6J mice. Longitudinal measurement of body composition, serum metabolites, and intrahepatic fat content, using in vivo magnetic resonance spectroscopy, reveals that mice fed the ketogenic diet over 12 wk remain lean, euglycemic, and hypoinsulinemic but accumulate hepatic lipid in a temporal pattern very distinct from animals fed the Western diet. Ketogenic diet-fed mice ultimately develop systemic glucose intolerance, hepatic endoplasmic reticulum stress, steatosis, cellular injury, and macrophage accumulation, but surprisingly insulin-induced hepatic Akt phosphorylation and whole-body insulin responsiveness are not impaired. Moreover, whereas hepatic Pparg mRNA abundance is augmented by both high-fat diets, each diet confers splice variant specificity. The distinctive nutrient milieu created by long-term administration of this low-carbohydrate, low-protein ketogenic diet in mice evokes unique signatures of nonalcoholic fatty liver disease and whole-body glucose homeostasis.

Cystamine reduces vascular stiffness in Western diet-fed female mice

2021 ◽  
Author(s):  
Francisco I. Ramirez-Perez ◽  
Francisco J. Cabral-Amador ◽  
Adam T. Whaley-Connell ◽  
Annayya R Aroor ◽  
Mariana Morales-Quinones ◽  
...  
Keyword(s):  
Tissue Transglutaminase ◽  
Vascular Wall ◽  
Aortic Pulse Wave Velocity ◽  
Western Diet ◽  
Vascular Stiffness ◽  
Mesenteric Arteries ◽  
Chow Diet ◽  
Obese Women ◽  
Arterial Stiffening ◽  
Female Mice

Consumption of diets high in fat, sugar and salt (Western diet, WD) is associated with accelerated arterial stiffening, a major independent risk factor for cardiovascular disease (CVD). Obese women are more prone to develop arterial stiffening leading to more frequent and severe CVD compared to men. As tissue transglutaminase (TG2) has been implicated in vascular stiffening, our goal herein was to determine the efficacy of cystamine, a non-specific TG2 inhibitor, at reducing vascular stiffness in female mice chronically fed a WD. Three experimental groups of female mice were created. One was fed regular chow diet (CD) for 43 weeks starting at four weeks of age. The second was fed a WD for the same 43 weeks, whereas a third cohort was fed WD, but also received cystamine (216 mg/kg/d) in the drinking water during the last eight weeks on the diet (WD+C). All vascular stiffness parameters assessed, including aortic pulse wave velocity and the incremental modulus of elasticity of isolated femoral and mesenteric arteries, were significantly increased in WD- vs. CD-fed mice, and reduced in WD+C vs. WD-fed mice. These changes coincided with respectively augmented and diminished vascular wall collagen and F-actin content, with no associated effect in blood pressure. In cultured human vascular smooth muscle cells, cystamine reduced TG2 activity, F-actin/G-actin ratio, collagen compaction capacity and cellular stiffness. We conclude that cystamine treatment represents an effective approach to reduce vascular stiffness in female mice in the setting of WD consumption, likely due to its TG2 inhibitory capacity.

scholarly journals Reducing Glut2 throughout the body does not result in cognitive behaviour differences in aged male mice

2020 ◽  
Vol 13 (1) ◽  
Author(s):  
Nicola Morrice ◽  
Lidy van Aalten ◽  
Alison McNeilly ◽  
Rory J. McCrimmon ◽  
Ewan R. Pearson ◽  
...  
Keyword(s):  
Glucose Transporter ◽  
Spatial Working Memory ◽  
The Body ◽  
Whole Body ◽  
Chow Diet ◽  
Neuronal Populations ◽  
Cognitive Behaviour ◽  
The Brain ◽  
Basic Cognition

Abstract Objectives GLUT2 is a major facilitative glucose transporter, expressed from the SLC2A2 gene, with essential roles in the liver. Recent work in mice has shown that preventing Glut2 production in specific neuronal populations increases sugar-seeking behaviour, highlighting the importance of Slc2a2 gene expression in the brain. It implies that reduced GLUT2 in the brain, due to genetic polymorphisms or disease, impacts health through behaviour change. Defects in glucose transport in the brain are observed in conditions including type-2 diabetes and dementia. Few studies have directly examined the effect of modulating neuronal glucose transporter expression on cognitive function. The aim of this study was to investigate whether inactivating one Slc2a2 allele throughout the body had major effects on cognition. Cognitive tests to assess recognition memory, spatial working memory and anxiety were performed in Slc2a2 whole-body heterozygous mice (i.e. reduced Glut2 mRNA and protein), alongside littermates expressing normal levels of the transporter. Results No significant effects on neurological functions and cognitive capabilities were observed in mice lacking one Slc2a2 allele when fed a chow diet. This suggests that the minor variations in GLUT2 levels that occur in the human population are unlikely to influence behaviour and basic cognition.

Microcirculatory and glycocalyx properties are lowered by high salt diet but augmented by western diet in genetically heterogeneous mice

2022 ◽  
Author(s):  
Xiangyu Zheng ◽  
Christina Deacon ◽  
Abigail J King ◽  
Daniel R Machin
Keyword(s):  
Barrier Function ◽  
Boundary Region ◽  
Microvascular Density ◽  
Western Diet ◽  
High Salt ◽  
Chow Diet ◽  
Male And Female ◽  
Female Mice ◽  
Normal Chow ◽  
Analysis System

Many individuals in industrialized societies consume a high salt, western diet, however, the effects of this diet on microcirculatory properties and glycocalyx barrier function are unknown. Young genetically heterogeneous male and female mice underwent 12 weeks of normal chow diet (NC), NC diet with 4% salt (NC4%), western diet (WD), or WD with 4% salt (WD4%). Microcirculatory properties and glycocalyx barrier function were evaluated in the mesenteric microcirculation using an intravital microscope equipped with an automated capture and analysis system. Total microvascular density summed across 4-25 μm microvessel segment diameters was lower in NC4% compared to NC and WD (P<0.05). Perfused boundary region (PBR), a marker of glycocalyx barrier function, averaged across 4-25 μm microvessel segment diameters was similar between NC and NC4%, as well as between WD and WD4% (P>0.05). PBR was lower in WD and WD4% compared to NC and NC4% (P<0.05), indicating augmented glycocalyx barrier function in WD and WD4%. There were strong, inverse relationships between PBR and adiposity and blood glucose (r=-0.44 to -0.61, P<0.05). In summary, NC4% induces deleterious effects on microvascular density, whereas WD augments glycocalyx barrier function. Interestingly, the combination of high salt, western diet in WD4% resulted in lower total microvascular density like NC4% and augmented glycocalyx barrier function like WD. These data suggest distinct microcirculatory adaptations to high salt and western diets that coincide when these diets are combined in young genetically heterogeneous male and female mice.

The Mammalian Facilitative Glucose Transporter Family

Physiology ◽  
1995 ◽  
Vol 10 (2) ◽  
pp. 67-71 ◽  
Author(s):  
DE James
Keyword(s):  
Gene Family ◽  
Glucose Homeostasis ◽  
Glucose Transporter ◽  
Whole Body ◽  
Large Gene Family ◽  
The Past ◽  
Large Gene ◽  
Transporter Family ◽  
Definition Of

Over the past few years, cloning studies have revealed a large gene family of facilitative glucose transporters in mammals. The definition of the unique characteristics of each member of this family has increased dramatically our understanding of the role of individual organs in regulation of whole body glucose homeostasis.

scholarly journals Adipocyte PHLPP2 inhibition prevents obesity-induced fatty liver

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
KyeongJin Kim ◽  
Jin Ku Kang ◽  
Young Hoon Jung ◽  
Sang Bae Lee ◽  
Raffaela Rametta ◽  
...  
Keyword(s):  
Fatty Liver ◽  
Whole Body ◽  
Acid Oxidation ◽  
Chow Diet ◽  
Peroxisome Proliferator ◽  
Obese Mice ◽  
Ph Domain ◽  
Peroxisome Proliferator Activated Receptor

AbstractIncreased adiposity confers risk for systemic insulin resistance and type 2 diabetes (T2D), but mechanisms underlying this pathogenic inter-organ crosstalk are incompletely understood. We find PHLPP2 (PH domain and leucine rich repeat protein phosphatase 2), recently identified as the Akt Ser473 phosphatase, to be increased in adipocytes from obese mice. To identify the functional consequence of increased adipocyte PHLPP2 in obese mice, we generated adipocyte-specific PHLPP2 knockout (A-PHLPP2) mice. A-PHLPP2 mice show normal adiposity and glucose metabolism when fed a normal chow diet, but reduced adiposity and improved whole-body glucose tolerance as compared to Cre- controls with high-fat diet (HFD) feeding. Notably, HFD-fed A-PHLPP2 mice show increased HSL phosphorylation, leading to increased lipolysis in vitro and in vivo. Mobilized adipocyte fatty acids are oxidized, leading to increased peroxisome proliferator-activated receptor alpha (PPARα)-dependent adiponectin secretion, which in turn increases hepatic fatty acid oxidation to ameliorate obesity-induced fatty liver. Consistently, adipose PHLPP2 expression is negatively correlated with serum adiponectin levels in obese humans. Overall, these data implicate an adipocyte PHLPP2-HSL-PPARα signaling axis to regulate systemic glucose and lipid homeostasis, and suggest that excess adipocyte PHLPP2 explains decreased adiponectin secretion and downstream metabolic consequence in obesity.

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