Glutamine metabolism in white adipocytes incubated in vitro

Abstract Liver X receptors (LXRs) are nuclear receptors with established roles in cholesterol, lipid, and carbohydrate metabolism, although their function in adipocytes is not well characterized. Increased adipose tissue mass in obesity is associated with increased adipocyte lipolysis. Fatty acids (FA) generated by lipolysis can be oxidized by mitochondrial β-oxidation, reesterified, or released from the adipocyte. The latter results in higher circulating levels of free FAs, in turn causing obesity-related metabolic complications. However, mitochondrial β-oxidation can at least in part counteract an increased output of FA into circulation. In this study, we provide evidence that activation of LXRs up-regulates mitochondrial β-oxidation in both human and murine white adipocytes. We also show that the expression of a kinase regulating the cellular fuel switch, pyruvate dehydrogenase kinase 4 (PDK4), is up-regulated by the LXR agonist GW3965 in both in vitro differentiated human primary adipocytes and differentiated murine 3T3-L1 cells. Moreover, activation of LXR causes PDK4-dependent phosphorylation of the pyruvate dehydrogenase complex, thereby decreasing its activity and attenuating glucose oxidation. The specificity of the GW3965 effect on oxidation was confirmed by RNA interference targeting LXRs. We propose that LXR has an important role in the regulation of substrate oxidation and the switch between lipids and carbohydrates as cellular fuel in both human and murine white adipocytes.

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Fraction B From Catfish Epidermal Secretions Kills Pancreatic Cancer Cells, Inhibits CD44 Expression and Stemness, and Alters Cancer Cell Metabolism

Frontiers in Pharmacology ◽

10.3389/fphar.2021.659590 ◽

2021 ◽

Vol 12 ◽

Author(s):

Jassim M. Al-Hassan ◽

Daoyan Wei ◽

Sharmistha Chakraborty ◽

Tara Conway ◽

Patrea Rhea ◽

...

Keyword(s):

Pancreatic Cancer ◽

Cancer Cells ◽

Glutamine Metabolism ◽

Stem Cell Marker ◽

Control Group ◽

Potential Candidate ◽

Cd44 Expression ◽

Tumor Bearing ◽

Pancreatic Cancer Cells

Pancreatic ductal adenocarcinoma (PDAC) is the fourth leading cause of cancer related death in western countries. The successful treatment of PDAC remains limited. We investigated the effect of Fraction B, which is a fraction purified from catfish (Arius bilineatus, Val.) skin secretions containing proteins and lipids, on PDAC biology both in-vivo and in-vitro. We report here that Fraction B potently suppressed the proliferation of both human and mouse pancreatic cancer cells in vitro and significantly reduced the growth of their relevant xenograft (Panc02) and orthotopic tumors (human Panc-1 cells) (p < 0.05). The Reverse Phase Protein Array (RPPA) data obtained from the tumor tissues derived from orthotopic tumor bearing mice treated with Fraction B showed that Fraction B altered the cancer stem cells related pathways and regulated glucose and glutamine metabolism. The down-regulation of the cancer stem cell marker CD44 expression was further confirmed in Panc-1 cells. CBC and blood chemistry analyses showed no systemic toxicity in Fraction B treated Panc-1 tumor bearing mice compared to that of control group. Our data support that Fraction B is a potential candidate for PDAC treatment.

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Dietary Supplement Enriched in Antioxidants and Omega-3 Promotes Glutamine Synthesis in Müller Cells: A Key Process against Oxidative Stress in Retina

Nutrients ◽

10.3390/nu13093216 ◽

2021 ◽

Vol 13 (9) ◽

pp. 3216

Author(s):

Maryvonne Ardourel ◽

Chloé Felgerolle ◽

Arnaud Pâris ◽

Niyazi Acar ◽

Khaoula Ramchani Ben Othman ◽

...

Keyword(s):

Oxidative Stress ◽

Müller Cells ◽

Nutritional Supplement ◽

Glutamine Metabolism ◽

Muller Cells ◽

Omega 3 ◽

Glutamine Synthesis ◽

The Impact

To prevent ocular pathologies, new generation of dietary supplements have been commercially available. They consist of nutritional supplement mixing components known to provide antioxidative properties, such as unsaturated fatty acid, resveratrol or flavonoids. However, to date, only one preclinical study has evaluated the impact of a mixture mainly composed of those components (Nutrof Total®) on the retina and demonstrated that in vivo supplementation prevents the retina from structural and functional injuries induced by light. Considering the crucial role played by the glial Müller cells in the retina, particularly to regulate the glutamate cycle to prevent damage in oxidative stress conditions, we questioned the impact of this ocular supplement on the glutamate metabolic cycle. To this end, various molecular aspects associated with the glutamate/glutamine metabolism cycle in Müller cells were investigated on primary Müller cells cultures incubated, or not, with the commercially mix supplement before being subjected, or not, to oxidative conditions. Our results demonstrated that in vitro supplementation provides guidance of the glutamate/glutamine cycle in favor of glutamine synthesis. These results suggest that glutamine synthesis is a crucial cellular process of retinal protection against oxidative damages and could be a key step in the previous in vivo beneficial results provided by the dietary supplementation.

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Liraglutide suppresses obesity and promotes browning of white fat via miR-27b in vivo and in vitro

Journal of International Medical Research ◽

10.1177/03000605211055059 ◽

2021 ◽

Vol 49 (11) ◽

pp. 030006052110550

Author(s):

Xing Wang ◽

Shuchun Chen ◽

Dan Lv ◽

Zelin Li ◽

Luping Ren ◽

...

Keyword(s):

Uncoupling Protein ◽

Density Lipoprotein ◽

Peroxisome Proliferator ◽

Sprague Dawley ◽

Peroxisome Proliferator Activated Receptor ◽

Protein Levels ◽

White Adipocytes ◽

White Fat

Objective To investigate the effect of liraglutide on the browning of white fat and the suppression of obesity via regulating microRNA (miR)-27b in vivo and in vitro. Methods Sprague-Dawley rats were fed a high-fat (HF) diet and 3T3-L1 pre-adipocytes were differentiated into mature white adipocytes. Rats and mature adipocytes were then treated with different doses of liraglutide. The mRNA and protein levels of browning-associated proteins, including uncoupling protein 1 (UCP1), PR domain containing 16 (PRDM16), CCAAT enhancer binding protein β (CEBPβ), cell death-inducing DFFA-like effector A (CIDEA) and peroxisome proliferator-activated receptor-γ-coactivator 1α (PGC-1α), were detected using quantitative real-time polymerase chain reaction and Western blotting. Results Liraglutide decreased body weight and reduced the levels of blood glucose, triglyceride and low-density lipoprotein cholesterol in HF diet-fed rats. Liraglutide increased the levels of UCP1, PRDM16, CEBPβ, CIDEA and PGC-1α in vivo and vitro. The levels of miR-27b were upregulated in HF diet-fed rats, whereas liraglutide reduced the levels of miR-27b. In vitro, overexpression of miR-27b decreased the mRNA and protein levels of UCP1, PRDM16, CEBPβ, CIDEA and PGC-1α. Transfection with the miR-27b mimics attenuated the effect of liraglutide on the browning of white adipocytes. Conclusion Liraglutide induced browning of white adipose through regulation of miR-27b.

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Betatrophin knockdown induces beiging and mitochondria biogenesis of white adipocytes

Journal of Endocrinology ◽

10.1530/joe-19-0447 ◽

2020 ◽

Vol 245 (1) ◽

pp. 93-100 ◽

Cited By ~ 1

Author(s):

Zhe-Zhen Liao ◽

Xiao-Yan Qi ◽

Ya-Di Wang ◽

Jiao-Yang Li ◽

Qian-Qian Gu ◽

...

Keyword(s):

Signaling Pathway ◽

Ampk Signaling ◽

White Adipocytes ◽

Beige Adipocytes ◽

Beige Fat ◽

Mitochondria Biogenesis ◽

Paracrine Actions ◽

White Fat

Remodeling of energy-storing white fat into energy-consuming beige fat has led to a promising new approach to alleviate adiposity. Several studies have shown adipokines can induce white adipose tissue (WAT) beiging through autocrine or paracrine actions. Betatrophin, a novel adipokine, has been linked to energy expenditure and lipolysis but not clearly clarified. Here, we using high-fat diet-induced obesity to determine how betatrophin modulate beiging and adiposity. We found that betatrophin-knockdown mice displayed less white fat mass and decreased plasma TG and NEFA levels. Consistently, inhibition of betatrophin leads to the phenotype change of adipocytes characterized by increased mitochondria contents, beige adipocytes and mitochondria biogenesis-specific markers both in vivo and in vitro. Of note, blocking AMP-activated protein kinase (AMPK) signaling pathway is able to abolish enhanced beige-like characteristics in betatrophin-knockdown adipocytes. Collectively, downregulation of betatrophin induces beiging in white adipocytes through activation of AMPK signaling pathway. These processes suggest betatrophin as a latent therapeutic target for obesity.

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Rhophilin-2 Upregulates Glutamine Synthetase by Stabilizing c-Myc Protein and Confers Resistance to Glutamine Deprivation in Lung Cancer

Frontiers in Oncology ◽

10.3389/fonc.2020.571384 ◽

2021 ◽

Vol 10 ◽

Author(s):

Dakai Xiao ◽

Jiaxi He ◽

Zhihua Guo ◽

Huiming He ◽

Shengli Yang ◽

...

Keyword(s):

Lung Cancer ◽

Glutamine Synthetase ◽

Lung Adenocarcinoma ◽

Cancer Cells ◽

Clinical Sample ◽

Glutamine Metabolism ◽

Lung Cancer Cells ◽

Mesenchymal Transformation ◽

Proliferation And Invasion

IntroductionRHPN2, a member of rhophilin family of rho-binding proteins, regulates actin cytoskeleton and vesicular trafficking, and promotes mesenchymal transformation in cancer. We have found that RHPN2 was significantly mutated in lung adenocarcinoma (LUAD). However, the role of RHPN2 in lung cancer is not fully understood.MethodsIn the present study, we investigated the expression of RHPN2 in 125 patients with LUAD by qRT-PCR and correlated its expression with clinical characteristics. The effects of RHPN2 on the proliferation and invasion of lung cancer cells were determined by CCK-8 and in vitro transwell assays, clonogenic assay, and xenograft mouse model. The RhoA pull down assay and Western blotting were performed to elucidate the mechanism of RNPN2 in tumorigenesis of lung cancer.ResultsRHPN2 was overexpressed in tumors from LUAD, and high levels of RHPN2 were associated with poor prognosis of LUAD patients. RHPN2 was required for proliferation and invasion of lung cancer cells. Intriguingly, overexpression of RHPN2 conferred the resistance to glutamine depletion in lung cancer cells. Mechanistic studies revealed that ectopic overexpression of RHPN2 promoted the stability of c-Myc protein via phosphorylation at Ser62 and increased c-Myc target glutamine synthetase (GS). Analysis of GS expression in clinical sample showed that the expression of GS was elevated in tumor cells. Kaplan-Meier analysis revealed that high levels of GS were significantly associated with worse overall survival time of the patients with LUAD.ConclusionsTaken together, this study suggested that RHPN2 was involved in tumorigenesis of lung cancer via modulating c-Myc stability and the expression of its target GS in lung adenocarcinoma, which links RHPN2 and glutamine metabolism.

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Evidence that 3-aminopicolinate stimulates glutamine metabolism by rat renal cortical tissue in vitro

Biochemical Pharmacology ◽

10.1016/0006-2952(82)90598-6 ◽

1982 ◽

Vol 31 (22) ◽

pp. 3689-3692 ◽

Cited By ~ 2

Author(s):

Daniel Durozard ◽

Gabriel Baverel

Keyword(s):

Glutamine Metabolism ◽

Cortical Tissue ◽

Renal Cortical Tissue

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Glutamine Metabolism in Skeletal Muscle of Glucocorticoid-Treated Rats

Clinical Science ◽

10.1042/cs0790139 ◽

1990 ◽

Vol 79 (2) ◽

pp. 139-147 ◽

Cited By ~ 32

Author(s):

M. Salleh M. Ardawi ◽

Yasir S. Jamal

Keyword(s):

Skeletal Muscle ◽

Exchange Rates ◽

Skeletal Muscles ◽

Plasma Concentrations ◽

Maximal Activity ◽

Glutamine Metabolism ◽

Dexamethasone Treatment ◽

Concentration Difference

1. The effect of dexamethasone (30 μg day−-1 100 g−-1 body weight) on the regulation of glutamine metabolism was studied in skeletal muscles of rats after 9 days of treatment. 2. Dexamethasone resulted in negative nitrogen balance, and produced increases in the plasma concentrations of alanine (23.4%) and insulin (158%) but a decrease in the plasma concentration of glutamine (28.7%). 3. Dexamethasone treatment increased the rate of glutamine production in muscle, skin and adipose tissue preparations, with muscle production accounting for over 90% of total glutamine produced by the hindlimb. 4. Blood flow and arteriovenous concentration difference measurements across the hindlimb showed an increase in the net exchange rates of glutamine (25.3%) and alanine (90.5%) in dexamethasone-treated rats compared with corresponding controls. 5. Dexamethasone treatment produced significant decreases in the concentrations of skeletal muscle glutamine (51.8%) and 2-oxoglutarate (50.8%). The concentrations of alanine (16.2%), pyruvate (45.9%), ammonia (43.3%) and inosine 5′-phosphate (141.8%) were increased. 6. The maximal activity of glutamine synthetase was increased (21–34%), but there was no change in that of glutaminase, in muscles of dexamethasone-treated rats. 7. It is concluded that glucocorticoid administration enhances the rates of release of both glutamine and alanine from skeletal muscle of rats (both in vitro and in vivo). This may be due to changes in efflux and/or increased intracellular formation of glutamine and alanine.

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Structure-based analysis of a natural GOT1-inhibitor Aspulvinone H arrests pancreatic ductal adenocarcinoma cells growth

10.22541/au.161881470.02929068/v1 ◽

2021 ◽

Author(s):

Zhang Yonghui ◽

Shan Yan ◽

Wei Song ◽

Qianqian Xu ◽

Changxing Qi ◽

...

Keyword(s):

Pancreatic Ductal Adenocarcinoma ◽

Anticancer Agents ◽

Active Sites ◽

Redox Homeostasis ◽

Xenograft Model ◽

Glutamine Metabolism ◽

Ductal Adenocarcinoma ◽

Biological Study

Pancreatic ductal adenocarcinoma (PDAC) cells are Gln-metabolism dependence, which can preferentially utilize glutamic oxaloacetate transaminase 1 (GOT1) to maintain the redox homeostasis of cancer cells. Therefore, small molecule inhibitors targeting GOT1 can be used as a new strategy for developing cancer therapies. Here, we identified a cyclobutyrolactone lignan, Aspulvinone H (AH), showing significant GOT1 inhibitory activity in vitro. The complex crystal structure of GOT1-AH elucidated the molecular mechanism, which AH and the cofactor pyrido-aldehyde 5-phosphate (PLP) competitively bound to the active sites of GOT1. Structure-activity relationship (SAR) analysis exhibited that the π-π stacking and isopentenyl side chain of aspulvinone were related to the inhibition of GOT1 activity. Further biological study indicated that AH could suppress glutamine metabolism, which made PDAC cells sensitive to oxidative stress and inhibited cell proliferation. Besides, AH exhibited potent in vivo antitumor activity in the SW1990 cell-induced xenograft model. These findings suggest that AH could be considered as a promising lead molecule for the development of PDAC anticancer agents.

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Fruit of Gardenia jasminoides Induces Mitochondrial Activation and Non-Shivering Thermogenesis through Regulation of PPARγ

Antioxidants ◽

10.3390/antiox10091418 ◽

2021 ◽

Vol 10 (9) ◽

pp. 1418

Author(s):

Woo Yong Park ◽

Gahee Song ◽

Ja Yeon Park ◽

Kwan-Il Kim ◽

Kwang Seok Ahn ◽

...

Keyword(s):

Uncoupling Protein ◽

Exposure Model ◽

Peroxisome Proliferator ◽

Peroxisome Proliferator Activated Receptor ◽

Gardenia Jasminoides ◽

White Adipocytes ◽

Beige Adipocytes ◽

Underlying Mechanisms ◽

Induced Changes

The extract of the Gardenia jasminoides fruit (GJFE) can been consumed as an herbal tea or used as a yellow dye. Recently, studies report that GFJE exerts inhibitory effects on lipid accumulation and adipogenesis in white adipocytes. We evaluated the thermogenic actions of GJFE by focusing on mitochondrial activation and studying the underlying mechanisms. To investigate the role of GJFE on thermogenesis in mice, we used an acute cold exposure model. After 2 weeks of feeding, the cold tolerance of GJFE-fed mice was notably increased compared to PBS-fed mice. This was due to an increase in thermogenic proteins in the inguinal white adipose tissue of the cold-exposed mice. Moreover, GJFE significantly increased thermogenic factors such as peroxisome proliferator-activated receptor gamma (PPARγ), uncoupling protein 1 (UCP1), and PPARγ coactivator 1 alpha (PGC1α) in vitro as well. Factors related to mitochondrial abundance and functions were also induced by GJFE in white and beige adipocytes. However, the treatment of PPARγ inhibitor abolished the GJFE-induced changes, indicating that activation of PPARγ is critical for the thermogenic effect of GJFE. In conclusion, GJFE induces thermogenic action by activating mitochondrial function via PPARγ activation. Through these findings, we suggest GJFE as a potential anti-obesity agent with a novel mechanism involving thermogenic action in white adipocytes.

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