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A special issue of International Journal of Molecular Sciences (ISSN 1422-0067). This special issue belongs to the section "Molecular Endocrinology and Metabolism".

Deadline for manuscript submissions: closed (31 December 2023) | Viewed by 15666

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Prof. Dr. Po-Shiuan Hsieh

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Graduate Institute of Medical Sciences, National Defense Medical Center, Taipei, Taiwan
Interests: obesity; diabetes; insulin resistance; energy metabolism; adipose tissue inflammation; brown fat biogenesis
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

This Special Issue of the International Journal of Molecular Sciences (IJMS) aims to publish valuable contributions to all aspects of research on energy metabolism and obesity, ranging from basic studies to clinical applications. We welcome studies on the omics approaches, epigenetic regulation, cellular and molecular mechanisms and therapeutics of human obesity and relevant in vivo and in vitro experimental models using cellular, molecular, biological, chemical and immunological approaches.

Topics include, but are not limited to:

Insulin, glucose metabolism and obesity;
Lipid metabolism and obesity;
Energy metabolism and weight control;
Obesity, metabolic health, and omics;
Epigenetic regulation of energy metabolism in obesity;
Molecular mechanism of insulin resistance and obesity;
Regulatory mechanisms of obesity-related metabolic disorders.

We also welcome reviews on these subjects, particularly those that challenge existing concepts.

Prof. Dr. Po-Shiuan Hsieh
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. International Journal of Molecular Sciences is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. There is an Article Processing Charge (APC) for publication in this open access journal. For details about the APC please see here. Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

energy metabolism
obesity
insulin resistance
glucose and lipid metabolism

Related Special Issue

Energy Metabolism and Obesity 2.0 in International Journal of Molecular Sciences

Published Papers (10 papers)

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Research

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19 pages, 1339 KiB

Open AccessArticle

Plant miR8126-3p and miR8126-5p Decrease Lipid Accumulation through Modulation of Metabolic Genes in a Human Hepatocyte Model That Mimics Steatosis

by Ester Díez-Sainz, Paula Aranaz, Ez-Zoubir Amri, José I. Riezu-Boj, Silvia Lorente-Cebrián and Fermín I. Milagro

Int. J. Mol. Sci. 2024, 25(3), 1721; https://doi.org/10.3390/ijms25031721 - 31 Jan 2024

Viewed by 677

Abstract

Plant-based food interventions are promising therapeutic approaches for non-alcoholic fatty liver disease (NAFLD) treatment, and microRNAs (miRNAs) have emerged as functional bioactive components of dietary plants involved in cross-kingdom communication. Deeper investigations are needed to determine the potential impact of plant miRNAs in NAFLD. This study aimed to identify plant miRNAs that could eventually modulate the expression of human metabolic genes and protect against the progression of hepatic steatosis. Plant miRNAs from the miRBase were used to predict human target genes, and miR8126-3p and miR8126-5p were selected as candidates for their potential role in inhibiting glucose and lipid metabolism-related genes. Human HepG2 cells were transfected with plant miRNA mimics and then exposed to a mixture of oleic and palmitic acids to mimic steatosis. miR8126-3p and miR8126-5p transfections inhibited the expression of the putative target genes QKI and MAPKAPK2, respectively, and had an impact on the expression profile of key metabolic genes, including PPARA and SREBF1. Quantification of intrahepatic triglycerides revealed that miR8126-3p and miR8126-5p attenuated lipid accumulation. These findings suggest that plant miR8126-3p and miR8126-5p would induce metabolic changes in human hepatocytes eventually protecting against lipid accumulation, and thus, they could be potential therapeutic tools for preventing and alleviating lipid accumulation. Full article

(This article belongs to the Special Issue Energy Metabolism and Obesity)

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12 pages, 2810 KiB

Open AccessArticle

Cyclodextrin-Mediated Cholesterol Depletion Induces Adiponectin Secretion in 3T3-L1 Adipocytes

by Yu-Ting Chiang, Ying-Yu Wu, Yu-Chun Lin, Yu-Yao Huang and Juu-Chin Lu

Int. J. Mol. Sci. 2023, 24(19), 14718; https://doi.org/10.3390/ijms241914718 - 28 Sep 2023

Viewed by 1054

Abstract

Adipocytes store a significant amount of cholesterol and triglycerides. However, whether cholesterol modulates adipocyte function remains largely unknown. We modulated the cholesterol level in adipocytes to examine its effect on the secretion of adiponectin, an important hormone specifically secreted by adipocytes. Treating differentiated 3T3-L1 adipocytes with 4 mM methyl-β-cyclodextrin (MβCD), a molecule with a high affinity for cholesterol, rapidly depleted cholesterol in adipocytes. Interestingly, MβCD treatment increased adiponectin in the medium without affecting its intracellular level, suggesting a modulation of secretion. By contrast, cholesterol addition did not affect adiponectin secretion, suggesting that cholesterol-depletion-induced intracellular cholesterol trafficking, but not reduced cholesterol level, accounted for MβCD-induced adiponectin secretion. MβCD-induced adiponectin secretion was reduced after 10 μg/mL U18666A treatment that suppressed cholesterol transport out of late endosomes/lysosomes. Depleting Niemann–Pick type C1 (NPC1) or NPC2 proteins, which mediate endosomal/lysosomal cholesterol export, consistently reduced MβCD-induced adiponectin secretion. Furthermore, treatment with 1 μM bafilomycin A1, which neutralized acidic endosomes/lysosomes, also attenuated MβCD-induced adiponectin secretion. Finally, MβCD treatment redistributed cellular adiponectin to lower-density fractions in sucrose gradient fractionation. Our results show that MβCD-mediated cholesterol depletion elevates the secretion of adiponectin, highlighting the involvement of endosomes and lysosomes in adiponectin secretion in adipocytes. Full article

(This article belongs to the Special Issue Energy Metabolism and Obesity)

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13 pages, 3391 KiB

Open AccessArticle

U0126 Compound Triggers Thermogenic Differentiation in Preadipocytes via ERK-AMPK Signaling Axis

by Sunday Amos Onikanni, Cheng-Ying Yang, Lloyd Noriega and Chih-Hao Wang

Int. J. Mol. Sci. 2023, 24(9), 7987; https://doi.org/10.3390/ijms24097987 - 28 Apr 2023

Viewed by 1511

Abstract

In recent years, thermogenic differentiation and activation in brown and white adipose tissues have been regarded as one of the major innovative and promising strategies for the treatment and amelioration of obesity. However, the pharmacological approach towards this process has had limited and insufficient commitments, which presents a greater challenge for obesity treatment. This research evaluates the effects of U0126 compound on the activation of thermogenic differentiation during adipogenesis. The results show that U0126 pretreatment primes both white and brown preadipocytes to upregulate thermogenic and mitochondrial genes as well as enhance functions during the differentiation process. We establish that U0126-mediated thermogenic differentiation induction occurs partially via AMPK activation signaling. The findings of this research suggest U0126 as a promising alternative ligand in pursuit of a pharmacological option to increase thermogenic adipocyte formation and improve energy expenditure. Thus it could pave the way for the discovery of therapeutic drugs for the treatment of obesity and its related complications. Full article

(This article belongs to the Special Issue Energy Metabolism and Obesity)

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16 pages, 2232 KiB

Open AccessArticle

Inguinal Fat Compensates Whole Body Metabolic Functionality in Partially Lipodystrophic Mice with Reduced PPARγ Expression

by Cherng-Shyang Chang, Shang-Shiuan Yu, Li-Chun Ho, Shu-Hsin Chao, Ting-Yu Chou, Ai-Ning Shao, Ling-Zhen Kao, Chia-Yu Chang, Yu-Hsin Chen, Ming-Shan Wu, Pei-Jane Tsai, Nobuyo Maeda and Yau-Sheng Tsai

Int. J. Mol. Sci. 2023, 24(4), 3904; https://doi.org/10.3390/ijms24043904 - 15 Feb 2023

Viewed by 1294

Abstract

Peroxisome proliferator-activated receptor γ (PPARγ) gene mutations in humans and mice lead to whole-body insulin resistance and partial lipodystrophy. It is unclear whether preserved fat depots in partial lipodystrophy are beneficial for whole-body metabolic homeostasis. We analyzed the insulin response and expression of metabolic genes in the preserved fat depots of Pparg^C/- mice, a familial partial lipodystrophy type 3 (FPLD3) mouse model resulting from a 75% decrease in Pparg transcripts. Perigonadal fat of Pparg^C/- mice in the basal state showed dramatic decreases in adipose tissue mass and insulin sensitivity, whereas inguinal fat showed compensatory increases. Preservation of inguinal fat metabolic ability and flexibility was reflected by the normal expression of metabolic genes in the basal or fasting/refeeding states. The high nutrient load further increased insulin sensitivity in inguinal fat, but the expression of metabolic genes became dysregulated. Inguinal fat removal resulted in further impairment of whole-body insulin sensitivity in Pparg^C/- mice. Conversely, the compensatory increase in insulin sensitivity of the inguinal fat in Pparg^C/- mice diminished as activation of PPARγ by its agonists restored insulin sensitivity and metabolic ability of perigonadal fat. Together, we demonstrated that inguinal fat of Pparg^C/- mice plays a compensatory role in combating perigonadal fat abnormalities. Full article

(This article belongs to the Special Issue Energy Metabolism and Obesity)

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20 pages, 2807 KiB

Open AccessArticle

The Synergistic Action of Metformin and Glycyrrhiza uralensis Fischer Extract Alleviates Metabolic Disorders in Mice with Diet-Induced Obesity

by Min-Kyeong Hong, Youngji Han, Hae-Jin Park, Mi-Rae Shin, Seong-Soo Roh and Eun-Young Kwon

Int. J. Mol. Sci. 2023, 24(2), 936; https://doi.org/10.3390/ijms24020936 - 04 Jan 2023

Cited by 3 | Viewed by 1946

Abstract

Metformin, an antidiabetic drug, and Glycyrrhiza uralensis Fischer (GU), an oriental medicinal herb, have been reported to exert anti-obesity effects. This study investigated the synergistic action of metformin and GU in improving diet-induced obesity. Mice were fed a normal diet, a high-fat diet (HFD), or HFD + 0.015% GU water extract for 8 weeks. The HFD and GU groups were then randomly divided into two groups and fed the following diets for the next 8 weeks: HFD with 50 mg/kg metformin (HFDM) and GU with 50 mg/kg metformin (GUM). GUM prevented hepatic steatosis and adiposity by suppressing expression of mRNAs and enzyme activities related to lipogenesis in the liver and upregulating the expression of adipocyte mRNAs associated with fatty acid oxidation and lipolysis, and as a result, improved dyslipidemia. Moreover, GUM improved glucose homeostasis by inducing glucose uptake in tissues and upregulating mRNA expressions associated with glycolysis in the liver and muscle through AMP-activated protein kinase activation. GUM also improved inflammation by increasing antioxidant activity in the liver and erythrocytes and decreasing inflammatory cytokine productions. Here, we demonstrate that GU and metformin exert synergistic action in the prevention of obesity and its complications. Full article

(This article belongs to the Special Issue Energy Metabolism and Obesity)

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16 pages, 2865 KiB

Open AccessArticle

Adipose Tissue-Derived CCL5 Enhances Local Pro-Inflammatory Monocytic MDSCs Accumulation and Inflammation via CCR5 Receptor in High-Fat Diet-Fed Mice

by Pei-Chi Chan, Chieh-Hua Lu, Hung-Che Chien, Yu-Feng Tian and Po-Shiuan Hsieh

Int. J. Mol. Sci. 2022, 23(22), 14226; https://doi.org/10.3390/ijms232214226 - 17 Nov 2022

Cited by 4 | Viewed by 1689

Abstract

The C-C chemokine motif ligand 5 (CCL5) and its receptors have recently been thought to be substantially involved in the development of obesity-associated adipose tissue inflammation and insulin resistance. However, the respective contributions of tissue-derived and myeloid-derived CCL5 to the etiology of obesity-induced adipose tissue inflammation and insulin resistance, and the involvement of monocytic myeloid-derived suppressor cells (MDSCs), remain unclear. This study used CCL5-knockout mice combined with bone marrow transplantation (BMT) and mice with local injections of shCCL5/shCCR5 or CCL5/CCR5 lentivirus into bilateral epididymal white adipose tissue (eWAT). CCL5 gene deletion significantly ameliorated HFD-induced inflammatory reactions in eWAT and protected against the development of obesity and insulin resistance. In addition, tissue (non-hematopoietic) deletion of CCL5 using the BMT method not only ameliorated adipose tissue inflammation by suppressing pro-inflammatory M-MDSC (CD11b⁺Ly6G⁻Ly6C^hi) accumulation and skewing local M1 macrophage polarization, but also recruited reparative M-MDSCs (CD11b⁺Ly6G⁻Ly6C^low) and M2 macrophages to the eWAT of HFD-induced obese mice, as shown by flow cytometry. Furthermore, modulation of tissue-derived CCL5/CCR5 expression by local injection of shCCL5/shCCR5 or CCL5/CCR5 lentivirus substantially impacted the distribution of pro-inflammatory and reparative M-MDSCs as well as macrophage polarization in bilateral eWAT. These findings suggest that an obesity-induced increase in adipose tissue CCL5-mediated signaling is crucial in the recruitment of tissue M-MDSCs and their trans-differentiation to tissue pro-inflammatory macrophages, resulting in adipose tissue inflammation and insulin resistance. Full article

(This article belongs to the Special Issue Energy Metabolism and Obesity)

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18 pages, 9189 KiB

Open AccessArticle

Contrast-Free FLIM Reveals Metabolic Changes in Pathological Islets of Langerhans

by Polina Ermakova, Alena Kashirina, Irina Kornilova, Aleksandra Bogomolova, Darya Myalik, Nasipbek Naraliev, Denis Kuchin, Liya Lugovaya, Elena Zagaynova, Vladimir Zagainov and Aleksandra Kashina

Int. J. Mol. Sci. 2022, 23(22), 13728; https://doi.org/10.3390/ijms232213728 - 08 Nov 2022

Viewed by 1254

Abstract

FLIM (Fluorescence Lifetime Imaging Microscopy) is a powerful tool that could be used in the future to diagnose islet cell recovery after therapy. The identification of appropriate FLIM parameters is required to determine islet quality and islet cell metabolism throughout the organ under various conditions of insulin deficiency. The aim of the work was to identify key FLIM parameters, changes of which are characteristic of pancreatic pathologies. The τm, τ1, τ2, α1, α2 and α1/α2 of free and bound forms of NAD(P)H of the islet cells of animals (rats and pigs) and of humans with and without pathologies were measured and analyzed. The data were confirmed by IHC and histological studies. We identified three FLIM parameters in islet cells from animals with streptozotocin (STZ)-induced diabetes mellitus (DM) and from humans with chronic pancreatitis + type 2 diabetes (T2D), which differ in the same way: τm and α2 take lower values compared to the nonpathological islet cells, while α1/α2 takes higher values. In islet cells from patients with adenocarcinoma (PDAC) and chronic pancreatitis, these parameters had reverse tendency relative to the norm or did not differ. Thus, minimally invasive and non-contrast FLIM methods may, in the future, be used to diagnose pathological islet cells. Full article

(This article belongs to the Special Issue Energy Metabolism and Obesity)

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19 pages, 3863 KiB

Open AccessArticle

Granulocytic MDSC with Deficient CCR5 Alleviates Lipogenesis and Inflammation in Nonalcoholic Fatty Liver Disease

by Tzu-Chieh Liao, Jiung-Pang Huang, Yu-Ting Tsai, Wei-Ching Shih, Chi-Chang Juan, Po-Shiuan Hsieh, Li-Man Hung and Chao-Lan Yu

Int. J. Mol. Sci. 2022, 23(21), 13048; https://doi.org/10.3390/ijms232113048 - 27 Oct 2022

Viewed by 2217

Abstract

C-C chemokine receptor type 5 (CCR5) positively contributes to the pathogenesis of nonalcoholic fatty liver disease (NAFLD), a common metabolic liver disease associated with chronic inflammation. CCR5 signaling also facilitates the immunosuppressive activity of a group of immature myeloid cells known as granulocytic myeloid-derived suppressor cells (g-MDSCs). While both hepatocyte and g-MDSC express CCR5, how CCR5 coordinates these two distinct cell types in the hepatic microenvironment remains largely unknown. Here, we used in vivo and ex vivo approaches to define the molecular details of how CCR5 mediates the crosstalk between hepatocytes and g-MDSCs in a mouse model of NAFLD. Global CCR5-deficient mice exhibited more severe steatosis, increased hepatic gene expression of lipogenesis, and exacerbated liver damage in diet-induced obesity. Either NAFLD or CCR5-deficiency per se is causative for the increase of g-MDSCs. Purified g-MDSCs have a higher survival rate in the fatty liver microenvironment, and blockade of CCR5 significantly decreases g-MDSCs’ expression of anti-inflammatory factors. On the other hand, the null of CCR5 signaling increases hepatocytes’ expression of lipogenic genes in the NAFLD microenvironment. Most importantly, inhibiting g-MDSCs’ CCR5 signaling in the fatty liver microenvironment dramatically reduces STAT3 signaling, lipogenic, and pro-inflammatory gene expression in primary hepatocytes. Adoptive cell transfer experiments further demonstrate that CCR5-deficient g-MDSCs mitigate hepatic lipogenic gene expression without facilitating pro-inflammatory cytokine production and liver damage in NAFLD mice. These results suggest that targeting g-MDSCs’ CCR5 signaling might serve as a potential therapeutic strategy for NAFLD. Full article

(This article belongs to the Special Issue Energy Metabolism and Obesity)

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Review

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19 pages, 1344 KiB

Open AccessReview

Histone Modifications in NAFLD: Mechanisms and Potential Therapy

by Yulei Shi and Wei Qi

Int. J. Mol. Sci. 2023, 24(19), 14653; https://doi.org/10.3390/ijms241914653 - 27 Sep 2023

Viewed by 1468

Abstract

Nonalcoholic fatty liver disease (NAFLD) is a progressive condition that encompasses a spectrum of liver disorders, beginning with the simple steatosis, progressing to nonalcoholic steatohepatitis (NASH), and possibly leading to more severe diseases, including liver cirrhosis and hepatocellular carcinoma (HCC). In recent years, the prevalence of NAFLD has increased due to a shift towards energy-dense dietary patterns and a sedentary lifestyle. NAFLD is also strongly associated with metabolic disorders such as obesity and hyperlipidemia. The progression of NAFLD could be influenced by a variety of factors, such as diet, genetic factors, and even epigenetic factors. In contrast to genetic factors, epigenetic factors, including histone modifications, exhibit dynamic and reversible features. Therefore, the epigenetic regulation of the initiation and progression of NAFLD is one of the directions under intensive investigation in terms of pathogenic mechanisms and possible therapeutic interventions. This review aims to discuss the possible mechanisms and the crucial role of histone modifications in the framework of epigenetic regulation in NAFLD, which may provide potential therapeutic targets and a scientific basis for the treatment of NAFLD. Full article

(This article belongs to the Special Issue Energy Metabolism and Obesity)

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20 pages, 2227 KiB

Open AccessReview

The Role of PIK3R1 in Metabolic Function and Insulin Sensitivity

by Ariel Tsay and Jen-Chywan Wang

Int. J. Mol. Sci. 2023, 24(16), 12665; https://doi.org/10.3390/ijms241612665 - 11 Aug 2023

Cited by 2 | Viewed by 1648

Abstract

PIK3R1 (also known as p85α) is a regulatory subunit of phosphoinositide 3-kinases (PI3Ks). PI3K, a heterodimer of a regulatory subunit and a catalytic subunit, phosphorylates phosphatidylinositol into secondary signaling molecules involved in regulating metabolic homeostasis. PI3K converts phosphatidylinositol 4,5-bisphosphate (PIP₂) to phosphatidylinositol 3,4,5-triphosphate (PIP₃), which recruits protein kinase AKT to the inner leaflet of the cell membrane to be activated and to participate in various metabolic functions. PIK3R1 stabilizes and inhibits p110 catalytic activity and serves as an adaptor to interact with insulin receptor substrate (IRS) proteins and growth factor receptors. Thus, mutations in PIK3R1 or altered expression of PIK3R1 could modulate the activity of PI3K and result in significant metabolic outcomes. Interestingly, recent studies also found PI3K-independent functions of PIK3R1. Overall, in this article, we will provide an updated review of the metabolic functions of PIK3R1 that includes studies of PIK3R1 in various metabolic tissues using animal models, the mechanisms modulating PIK3R1 activity, and studies on the mutations of human PIK3R1 gene. Full article

(This article belongs to the Special Issue Energy Metabolism and Obesity)

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