The polymorphisms of UCP2 and UCP3 genes associated with fat metabolism, obesity and diabetes

The impact of solute carrier proteins on disrupting substance regulation in metabolic disorders: insights and clinical applications

Carbohydrates, lipids, bile acids, various inorganic salt ions and organic acids are the main nutrients or indispensable components of the human body. Dysregulation in the processes of absorption, transport, metabolism, and excretion of these metabolites can lead to the onset of severe metabolic disorders, such as type 2 diabetes, non-alcoholic fatty liver disease, gout and hyperbilirubinemia. As the second largest membrane receptor supergroup, several major families in the solute carrier (SLC) supergroup have been found to play key roles in the transport of substances such as carbohydrates, lipids, urate, bile acids, monocarboxylates and zinc ions. Based on common metabolic dysregulation and related metabolic substances, we explored the relationship between several major families of SLC supergroup and metabolic diseases, providing examples of drugs targeting SLC proteins that have been approved or are currently in clinical/preclinical research as well as SLC-related diagnostic techniques that are in clinical use or under investigation. By highlighting these connections, we aim to provide insights that may contribute to the development of improved treatment strategies and targeted therapies for metabolic disorders.

Mitochondrial uncoupling protein 2: a central player in pancreatic disease pathophysiology

Pancreatic diseases pose considerable health challenges due to their complex etiology and limited therapeutic options. Mitochondrial uncoupling protein 2 (UCP2), highly expressed in pancreatic tissue, participates in numerous physiological processes and signaling pathways, indicating its potential relevance in these diseases. Despite this, UCP2's role in acute pancreatitis (AP) remains underexplored, and its functions in chronic pancreatitis (CP) and pancreatic steatosis are largely unknown. Additionally, the mechanisms connecting various pancreatic diseases are intricate and not yet fully elucidated. Given UCP2's diverse functionality, broad expression in pancreatic tissue, and the distinct pathophysiological features of pancreatic diseases, this review offers a comprehensive analysis of current findings on UCP2's involvement in these conditions. We discuss recent insights into UCP2's complex regulatory mechanisms, propose that UCP2 may serve as a central regulatory factor in pancreatic disease progression, and hypothesize that UCP2 dysfunction could significantly contribute to disease pathogenesis. Understanding UCP2's role and mechanisms in pancreatic diseases may pave the way for innovative therapeutic and diagnostic approaches.

Beyond Calories: Individual Metabolic and Hormonal Adaptations Driving Variability in Weight Management-A State-of-the-Art Narrative Review

The global rise in obesity underscores the need for effective weight management strategies that address individual metabolic and hormonal variability, moving beyond the simplistic "calories in, calories out" model. Body types-ectomorph, mesomorph, and endomorph-provide a framework for understanding the differences in fat storage, muscle development, and energy expenditure, as each type responds uniquely to caloric intake and exercise. Variability in weight outcomes is influenced by factors such as genetic polymorphisms and epigenetic changes in hormonal signaling pathways and metabolic processes, as well as lifestyle factors, including nutrition, exercise, sleep, and stress. These factors impact the magnitude of lipogenesis and myofibrillar protein synthesis during overfeeding, as well as the extent of lipolysis and muscle proteolysis during caloric restriction, through complex mechanisms that involve changes in the resting metabolic rate, metabolic pathways, and hormonal profiles. Precision approaches, such as nutrigenomics, indirect calorimetry, and artificial-intelligence-based strategies, can potentially leverage these insights to create individualized weight management strategies aligned with each person's unique metabolic profile. By addressing these personalized factors, precision nutrition offers a promising pathway to sustainable and effective weight management outcomes. The main objective of this review is to examine the metabolic and hormonal adaptations driving variability in weight management outcomes and explore how precision nutrition can address these challenges through individualized strategies.

Evaluating a new obesity indicator for stroke risk prediction: comparative cohort analysis in rural settings of two nations

BACKGROUND

While the TyG index has been studied in relation to stroke risk, there is a lack of research integrating fat distribution indicators like Body Roundness Index (BRI) and Fat Mass Index (FMI). Additionally, comparative studies across multiple regions are scarce. This study investigates the association between obesity-related parameters and stroke incidence, examining the mediation effects of multimorbidity, using data from rural areas in China and the United Kingdom.

METHODS

This cohort study included 60,685 participants (6,980 from China and 53,705 from UK). The obesity-related parameters were calculated using established formulas. The TyG index was determined as ln [TG (mg/dL) × GLU (mg/dL) / 2]. Additionally, composite indices were created by multiplying the TyG index by BMI, WC, FMI, and RBI to assess obesity-related risks. Cox regression analyses were employed on the relationship between Triglyceride Glucose index related parameters and stroke risk. Multiple mediation analysis was applied to assess the contributions of multimorbidity to obesity indicators in stroke occurrence.

RESULTS

After excluding those who developed stroke within two years of enrollment, the Chinese cohort (6,638 subjects, median follow-up 4.33 years) had 237 ischemic and 21 hemorrhagic strokes. The UK cohort (53,631 subjects, median follow-up 13.85 years) had 742 ischemic and 316 hemorrhagic strokes. Chinese residents had lower BMI but higher visceral obesity (BRI), higher prevalence of multimorbidity, and higher stroke incidence compared to UK residents. Cox analyses demonstrated significant associations between BMI/TyG indices and ischemic stroke in both Chinese and UK populations, which diminished after adjusting for multimorbidity. In the Chinese rural cohort, only TyG-BRI (HR:1.13, 95%CI:0.99-1.30) approached statistical significance after full adjustment for mediators. In contrast, in the UK cohort, significant associations persisted for most TyG Index indicators when full adjustment for mediators, including BMI (HR: 1.17, 95% CI: 1.09-1.26), TyG-BMI (HR: 1.16, 95% CI: 1.07-1.26), TyG-WC (HR: 1.13, 95% CI: 1.03-1.25), TyG-FMI (HR: 1.17, 95% CI: 1.07-1.28), and TyG-RBI (HR: 1.15, 95% CI: 1.06-1.24). TyG-BRI also showed the best predictive performance for ischemic stroke in Chinese rural residents (AUC > 0.7) and exhibited an almost linear relationship with ischemic stroke occurrence. Additionally, TyG-BRI presented a U-shaped relationship with the risk of hemorrhagic stroke incidence in the UK (p overall = 0.041, p non-linear = 0.017). Multimorbidity mediated the relationship between TyG indices, and ischemic stroke incidence in both cohorts. The mediation percentage for multimorbidity was higher than the sum of individual chronic diseases, with a higher mediation percentage in the Chinese cohort (up to 51%) compared to the UK cohort (up to 27.2%).

CONCLUSIONS

Chinese rural residents exhibit higher levels of visceral obesity compared to residents in UK, leading to greater stroke susceptibility mediated by multimorbidity. These findings underscore the importance of comprehensive management of multimorbidity for stroke prevention. The TyG-BRI may serve as a promising predictor of ischemic stroke incidence among rural community residents.

Dynamic transcriptome profiles of skeletal muscle growth and development in Shaziling and Yorkshire pigs using RNA-sequencing

BACKGROUND

We previously demonstrated that Shaziling and Yorkshire pigs differ in growth rate and meat quality. However, the molecular mechanisms responsible for such phenotypic differences remain unclear. In the present study, we performed a transcriptomic analysis of 36 longissimus dorsi (LM) and 36 soleus (SM) muscle samples from Shaziling and Yorkshire pigs at six postnatal stages (30, 60, 90, 150, 210 and 300 days) to explore the differences in postnatal skeletal muscle of Shaziling and Yorkshire pigs.

RESULTS

Muscle morphological changes and the number of differentially expressed genes indicated the two stages of 60-90 days and 150-210 days were critical for the muscle growth and development in Shaziling pigs. Genes such as FLNC, COL1A1, NRAP, SMYD1, TNNI3, CRYAB and PDLIM3 played vital roles in the muscle growth, and genes such as CCDC71L, LPIN1, CPT1A, UCP3, NR4A3 and PDK4 played dominant roles in the lipid metabolism. Additionally, in contrast to the LM, the percentage of slow-twitch muscle fibers in the SM of both breeds consistently decreased from 30 to 150 days of age, but there was a significant rebound at 210 days of age. However, the percentage of slow-twitch muscle fibers in the SM of Shaziling pigs was higher than that in Yorkshire pigs, which may be associated with the calcium signaling pathway and the PPARβ/δ signaling pathway.

CONCLUSION

The present study detected two critical periods and many functional genes for the muscle growth and development of Shaziling pigs, and showed differences in muscle fiber characteristics between Shaziling and Yorkshire pigs. © 2024 Society of Chemical Industry.

Metabolic basis of solute carrier transporters in treatment of type 2 diabetes mellitus

Solute carriers (SLCs) constitute the largest superfamily of membrane transporter proteins. These transporters, present in various SLC families, play a vital role in energy metabolism by facilitating the transport of diverse substances, including glucose, fatty acids, amino acids, nucleotides, and ions. They actively participate in the regulation of glucose metabolism at various steps, such as glucose uptake (e.g., SLC2A4/GLUT4), glucose reabsorption (e.g., SLC5A2/SGLT2), thermogenesis (e.g., SLC25A7/UCP-1), and ATP production (e.g., SLC25A4/ANT1 and SLC25A5/ANT2). The activities of these transporters contribute to the pathogenesis of type 2 diabetes mellitus (T2DM). Notably, SLC5A2 has emerged as a valid drug target for T2DM due to its role in renal glucose reabsorption, leading to groundbreaking advancements in diabetes drug discovery. Alongside SLC5A2, multiple families of SLC transporters involved in the regulation of glucose homeostasis hold potential applications for T2DM therapy. SLCs also impact drug metabolism of diabetic medicines through gene polymorphisms, such as rosiglitazone (SLCO1B1/OATP1B1) and metformin (SLC22A1-3/OCT1-3 and SLC47A1, 2/MATE1, 2). By consolidating insights into the biological activities and clinical relevance of SLC transporters in T2DM, this review offers a comprehensive update on their roles in controlling glucose metabolism as potential drug targets.

Uncoupling protein 2 modulates polarization and metabolism of human primary macrophages via glycolysis and the NF‑κB pathway

Metabolic abnormalities, particularly the M1/M2 macrophage imbalance, play a critical role in the development of various diseases, leading to severe inflammatory responses. The present study aimed to investigate the role of uncoupling protein 2 (UCP2) in regulating macrophage polarization, glycolysis, metabolic reprogramming, reactive oxygen species (ROS) and inflammation. Primary human macrophages were first polarized into M1 and M2 subtypes, and these two subtypes were infected by lentivirus-mediated UCP2 overexpression or knockdown, followed by enzyme-linked immunosorbent assay, reverse transcription-quantitative PCR, western blotting and flow cytometry to analyze the effects of UCP2 on glycolysis, oxidative phosphorylation (OXPHOS), ROS production and cytokine secretion, respectively. The results demonstrated that UCP2 expression was suppressed in M1 macrophages and increased in M2 macrophages, suggesting its regulatory role in macrophage polarization. UCP2 overexpression decreased macrophage glycolysis, increased OXPHOS, decreased ROS production, and led to the conversion of M1 polarization to M2 polarization. This process involved NF-κB signaling to regulate the secretion profile of cytokines and chemokines and affected the expression of key enzymes of glycolysis and a key factor for maintaining mitochondrial homeostasis (nuclear respiratory factor 1). UCP2 knockdown in M2 macrophages exacerbated inflammation and oxidative stress by promoting glycolysis, which was attenuated by the glycolysis inhibitor 2-deoxyglucose. These findings highlight the critical role of UCP2 in regulating macrophage polarization, metabolism, inflammation and oxidative stress through its effects on glycolysis, providing valuable insights into potential therapeutic strategies for macrophage-driven inflammatory and metabolic diseases.

Identification and Characteristics of Novel Mutations in Nonsyndromic Monogenic Obesity

Nonsyndromic monogenic obesity (NSMO) is a class of individual obesity that is independent of the environment and caused by a single gene mutation. It is mostly caused by mutations in LEP, LEPR, PCSK1, as well as some rare mutations in UCP3, NR0B2, and PPARG. Among 30 obesity patients, five patients are identified with positive gene detection. For the first time, the c.624C>T mutation associated with PCSK1, and the c.50G>A and c.293_301delinsAC mutations associated with NR0B2, as well as the obesity phenotype mutation (c.284A>G) associated with PPARG is confirmed. Following this, the genotype-clinical phenotype, mutation hotspots, and mutation distributions of each gene are summarized, and the genetic characteristics of NSMO are analyzed. The locations of mutation c.50G>A, and c.284A>G are highly conserved according to the sequencing alignment. According to the findings, the c.624C>T mutation in PCSK1 is a newly discovered synonymous mutation, but it can result in significant early-onset obesity. Additionally, the mutation of c.284A>G(PPARG) can lead to a variety of clinical phenotypes and the mutation of UCP3 and NR0B2 may increase the risk of type 2 diabetes mellitus. This study enriches the human NSMO gene mutation database and provides a scientific basis for clinically accurate diagnosis and treatment.

sfkit: a web-based toolkit for secure and federated genomic analysis

Advances in genomics are increasingly depending upon the ability to analyze large and diverse genomic data collections, which are often difficult to amass due to privacy concerns. Recent works have shown that it is possible to jointly analyze datasets held by multiple parties, while provably preserving the privacy of each party's dataset using cryptographic techniques. However, these tools have been challenging to use in practice due to the complexities of the required setup and coordination among the parties. We present sfkit, a secure and federated toolkit for collaborative genomic studies, to allow groups of collaborators to easily perform joint analyses of their datasets without compromising privacy. sfkit consists of a web server and a command-line interface, which together support a range of use cases including both auto-configured and user-supplied computational environments. sfkit provides collaborative workflows for the essential tasks of genome-wide association study (GWAS) and principal component analysis (PCA). We envision sfkit becoming a one-stop server for secure collaborative tools for a broad range of genomic analyses. sfkit is open-source and available at: https://sfkit.org.

The intestinal microbiome associated with lipid metabolism and obesity in humans and animals

Intestinal microbiota is considered to play an integral role in maintaining health of host by modulating several physiological functions including nutrition, metabolism and immunity. Accumulated data from human and animal studies indicate that intestinal microbes can affect lipid metabolism in host through various direct and indirect biological mechanisms. These mechanisms include the production of various signalling molecules by the intestinal microbiome, which exert a strong effect on lipid metabolism, bile secretion in the liver, reverse transport of cholesterol and energy expenditure and insulin sensitivity in peripheral tissues. This review discusses the findings of recent studies suggesting an emerging role of intestinal microbiota and its metabolites in regulating lipid metabolism and the association of intestinal microbiota with obesity. Additionally, we discuss the controversies and challenges in this research area. However, intestinal micro-organisms are also affected by some external factors, which in turn influence the regulation of microbial lipid metabolism. Therefore, we also discuss the effects of probiotics, prebiotics, diet structure, exercise and other factors on intestinal microbiological changes and lipid metabolism regulation.

Reviewed and updated Algorithm for Genetic Characterization of Syndromic Obesity Phenotypes

Background: Individuals with a phenotype of early-onset severe obesity associated with intellectual disability can have molecular diagnoses ranging from monogenic to complex genetic traits. Severe overweight is the major sign of a syndromic physical appearance and predicting the influence of a single gene and/or polygenic risk profile is extremely complicated among the majority of the cases. At present, considering rare monogenic bases as the principal etiology for the majority of obesity cases associated with intellectual disability is scientifically poor. The diversity of the molecular bases responsible for the two entities makes the appliance of the current routinely powerful genomics diagnostic tools essential. Objective: Clinical investigation of these difficult-to-diagnose patients requires pediatricians and neurologists to use optimized descriptions of signs and symptoms to improve genotype correlations. Methods: The use of modern integrated bioinformatics strategies which are conducted by experienced multidisciplinary clinical teams. Evaluation of the phenotype of the patient's family is also of importance. Results: The next step involves discarding the monogenic canonical obesity syndromes and considering infrequent unique molecular cases, and/or then polygenic bases. Adequate management of the application of the new technique and its diagnostic phases is essential for achieving good cost/efficiency balances. Conclusion: With the current clinical management, it is necessary to consider the potential coincidence of risk mutations for obesity in patients with genetic alterations that induce intellectual disability. In this review, we describe an updated algorithm for the molecular characterization and diagnosis of patients with a syndromic obesity phenotype.

Role of Uncoupling Protein 2 Gene Polymorphisms on the Risk of Ischemic Stroke in a Sardinian Population

The mitochondrial uncoupling protein 2 (UCP2) acts as an anion transporter and as an antioxidant factor able to reduce the reactive oxygen species level. Based on its effects, UCP2 prevents the membrane lipids, proteins, and DNA damage while preserving normal cellular functions. Many variants have been identified within the human UCP2. Some of them were associated with a higher risk of obesity, diabetes and cardiovascular diseases in different populations. UCP2 appears a suitable candidate also for the risk of ischemic stroke. In the current study, we investigated the possible association between few variants of UCP2 (rs659366, rs660339, rs1554995310) and the risk of ischemic stroke in a genetically homogenous cohort of cases and controls selected in Sardinia Island. This population has been previously analysed for other candidate genes. A total of 250 cases of ischemic stroke and 241 controls were enrolled in the study. The allelic/genotypic distribution of the 3 UCP2 variants was characterized and compared among cases and controls. The results of our study confirmed known risk factors for ischemic stroke: age, history of smoking, hypertension, hypercholesterolemia, and atrial fibrillation. No association was found between the 3 UCP2 variants and the risk of ischemic stroke in our Sardinian cohort.

Lack of Association Between 11 Gene Polymorphisms on Weight Loss One Year After Roux-en-Y Gastric Bypass Surgery in Women

BACKGROUND

Although effective, the impact of bariatric surgery on weight loss is variable, and little is known about the influence of single nucleotide polymorphisms (SNPs). This study investigated the association of eleven SNPs related to obesity with weight loss one year after Roux-Y gastric bypass (RYGB) surgery in female patients.

METHODS

This prospective study included 351 women with obesity. The genotypes for eleven SNPs (GHRL - rs26802; GHSR - rs572169; LEP - rs7799039; LEPR - rs1137101; 5HT2C - rs3813929; UCP2 - rs659366; UCP3 - rs1800849; SH2B1 - rs7498665; TAS1R2 - rs35874116; TAS1R2 - rs9701796; FTO - rs9939609) were determined using real-time polymerase chain reaction (PCR) and TaqMan assays. Anthropometric measurements were performed before and one year after RYGB surgery. To evaluate the factors that influenced the proportion of weight loss 1 year after surgery, beta regression analysis was used. The models were estimated using the SAS software GLIMMIX procedure. The level of significance adopted for the statistical tests was 5%.

RESULTS

The average percentage of total body weight loss in one year was 64.4 ± 5.8% and the median was 65.0%. In assessing the proportion of weight loss in one year after surgery, using univariate analysis (beta regression), no single nucleotide polymorphisms (SNPs) influenced weight loss. And in the multiple analysis, with stepwise process of variable selection, no variable was significant to compose the multiple model.

CONCLUSION

The 11 SNPs investigated did not influence weight loss one year after RYGB surgery in female patients. This result indicates that individual behaviors and other factors might better contribute to the magnitude of loss weight loss in a short period after bariatric surgery. This article is protected by copyright. All rights reserved.

Association of UCP3 Polymorphisms with Nonalcoholic Steatohepatitis and Metabolic Syndrome in Nonalcoholic Fatty Liver Disease Brazilian Patients

Background: We investigated the possible association of uncoupling protein 3 gene (UCP3) single nucleotide polymorphisms (SNPs) with nonalcoholic steatohepatitis (NASH) and metabolic syndrome (MetS) in nonalcoholic fatty liver disease (NAFLD) Brazilian patients. Methods: UCP3 SNPs rs1726745, rs3781907, and rs11235972 were genotyped in 158 biopsy-proven NAFLD Brazilian patients. Statistics was performed with JMP, R, and SHEsis softwares. Results: The TT genotype of rs1726745 was associated with less occurrence of MetS (P = 0.006) and with lower body mass index (BMI) in the entire NAFLD sample (P = 0.01) and in the NASH group (P = 0.02). The rs1726745-T was associated with lower values of AST (P = 0.001), ALT (P = 0.0002), triglycerides (P = 0.01), and total cholesterol (P = 0.02) in the entire NAFLD sample. Between groups, there were lower values of aminotransferases strictly in individuals with NASH (AST, P = 0.002; ALT, P = 0.0007) and with MetS (AST, P = 0.002; ALT, P = 0.001). The rs3781907-G was associated with lower GGT elevation values in the entire NAFLD sample (P = 0.002), in the NASH group (P = 0.004), and with MetS group (P = 0.003) and with protection for advanced fibrosis (P = 0.01). The rs11235972-A was associated with lower GGT values in the entire NAFLD sample (P = 0.006) and in the NASH group (P = 0.01) and with MetS group (P = 0.005), with fibrosis absence (P = 0.01) and protection for advanced fibrosis (P = 0.01). The TAA haplotype was protective for NASH (P = 0.002), and TGG haplotype was protective for MetS (P = 0.01). Conclusion: UCP3 gene variants were associated with protection against NASH and MetS, in addition to lower values of liver enzymes, lipid profile, BMI and, lesser fibrosis severity in the studied population.

Integrative system biology and mathematical modeling of genetic networks identifies shared biomarkers for obesity and diabetes

Obesity and type 2 and diabetes mellitus (T2D) are two dual epidemics whose shared genetic pathological mechanisms are still far from being fully understood. Therefore, this study is aimed at discovering key genes, molecular mechanisms, and new drug targets for obesity and T2D by analyzing the genome wide gene expression data with different computational biology approaches. In this study, the RNA-sequencing data of isolated primary human adipocytes from individuals who are lean, obese, and T2D was analyzed by an integrated framework consisting of gene expression, protein interaction network (PIN), tissue specificity, and druggability approaches. Our findings show a total of 1932 unique differentially expressed genes (DEGs) across the diabetes versus obese group comparison (p≤0.05). The PIN analysis of these 1932 DEGs identified 190 high centrality network (HCN) genes, which were annotated against 3367 GO terms and functional pathways, like response to insulin signaling, phosphorylation, lipid metabolism, glucose metabolism, etc. (p≤0.05). By applying additional PIN and topological parameters to 190 HCN genes, we further mapped 25 high confidence genes, functionally connected with diabetes and obesity traits. Interestingly, ERBB2, FN1, FYN, HSPA1A, HBA1, and ITGB1 genes were found to be tractable by small chemicals, antibodies, and/or enzyme molecules. In conclusion, our study highlights the potential of computational biology methods in correlating expression data to topological parameters, functional relationships, and druggability characteristics of the candidate genes involved in complex metabolic disorders with a common etiological basis.

Lycium barbarum Polysaccharides Promotes Mitochondrial Biogenesis and Energy Balance in a NAFLD Cell Model

OBJECTIVE

To explore the protective effect and underlying mechanism of Lycium barbarum polysaccharides (LBP) in a non-alcoholic fatty liver disease (NAFLD) cell model.

METHODS

Normal human hepatocyte LO2 cells were treated with 1 mmol/L free fatty acids (FFA) mixture for 24 h to induce NAFLD cell model. Cells were divided into 5 groups, including control, model, low-, medium- and high dose LBP (30,100 and 300 µg/mL) groups. The monosaccharide components of LBP were analyzed with high performance liquid chromatography. Effects of LBP on cell viability and intracellular lipid accumulation were assessed by cell counting Kit-8 assay and oil red O staining, respectively. Triglyceride (TG), alanine aminotransferase (ALT), aspartate aminotransferase (AST), adenosine triphosphate (ATP) and oxidative stress indicators were evaluated. Energy balance and mitochondrial biogenesis related mRNA and proteins were determined by quantitative real-time polymerase chain reaction and Western blot, respectively.

RESULTS

Heteropolysaccharides with mannose and glucose are the main components of LBP. LBP treatment significantly decreased intracellular lipid accumulation as well as TG, ALT, AST and malondialdehyde levels (P<0.05 or P<0.01), increased the levels of superoxide dismutase, phospholipid hydroperoxide glutathione peroxidase, catalase, and ATP in NAFLD cell model (P<0.05). Meanwhile, the expression of uncoupling protein 2 was down-regulated and peroxisome proliferator-activated receptor gamma coactivator-1α/nuclear respiratory factor 1/mitochondrial transcription factor A pathway was up-regulated (P<0.05).

CONCLUSION

LBP promotes mitochondrial biogenesis and improves energy balance in NAFLD cell model.

Identification of key genes affecting porcine fat deposition based on co-expression network analysis of weighted genes

BACKGROUND

Fat deposition is an important economic consideration in pig production. The amount of fat deposition in pigs seriously affects production efficiency, quality, and reproductive performance, while also affecting consumers' choice of pork. Weighted gene co-expression network analysis (WGCNA) is effective in pig genetic studies. Therefore, this study aimed to identify modules that co-express genes associated with fat deposition in pigs (Songliao black and Landrace breeds) with extreme levels of backfat (high and low) and to identify the core genes in each of these modules.

RESULTS

We used RNA sequences generated in different pig tissues to construct a gene expression matrix consisting of 12,862 genes from 36 samples. Eleven co-expression modules were identified using WGCNA and the number of genes in these modules ranged from 39 to 3,363. Four co-expression modules were significantly correlated with backfat thickness. A total of 16 genes (RAD9A, IGF2R, SCAP, TCAP, SMYD1, PFKM, DGAT1, GPS2, IGF1, MAPK8, FABP, FABP5, LEPR, UCP3, APOF, and FASN) were associated with fat deposition.

CONCLUSIONS

RAD9A, TCAP, SMYD1, PFKM, GPS2, and APOF were the key genes in the four modules based on the degree of gene connectivity. Combining these results with those from differential gene analysis, SMYD1 and PFKM were proposed as strong candidate genes for body size traits. This study explored the key genes that regulate porcine fat deposition and lays the foundation for further research into the molecular regulatory mechanisms underlying porcine fat deposition.

The effect of cranberry consumption on lipid metabolism and inflammation in human apo A-I transgenic mice fed a high-fat and high-cholesterol diet

Lipid metabolism and inflammation contribute to CVD development. This study investigated whether the consumption of cranberries (CR; Vaccinium macrocarpon) can alter HDL metabolism and prevent inflammation in mice expressing human apo A-I transgene (hApoAITg), which have similar HDL profiles to those of humans. Male hApoAITg mice were fed a modified American Institute of Nutrition-93M high-fat/high-cholesterol diet (16 % fat, 0·25 % cholesterol, w/w; n 15) or the high-fat/high-cholesterol diet containing CR (5 % dried CR powder, w/w, n 16) for 8 weeks. There were no significant differences in body weight between the groups. Serum total cholesterol, non-HDL-cholesterol and TAG concentrations were significantly lower in the control than CR group with no significant differences in serum HDL-cholesterol and apoA-I. Mice fed CR showed significantly lower serum lecithin-cholesterol acyltransferase activity than the control. Liver weight and steatosis were not significantly different between the groups, but hepatic expression of genes involved in cholesterol metabolism was significantly lower in the CR group. In the epididymal white adipose tissue (eWAT), the CR group showed higher weights with decreased expression of genes for lipogenesis and fatty acid oxidation. The mRNA abundance of F4/80, a macrophage marker and the numbers of crown-like structures were less in the CR group. In the soleus muscle, the CR group also demonstrated higher expression of genes for fatty acid β-oxidation and mitochondrial biogenesis than those of the control. In conclusion, although CR consumption elicited minor effects on HDL metabolism, it prevented obesity-induced inflammation in eWAT with concomitant alterations in soleus muscle energy metabolism.

-866G/A and Ins/Del polymorphisms in UCP2 gene are associated with reduced short-term weight loss in patients who underwent Roux-en-Y gastric bypass

BACKGROUND

Uncoupling protein 2 (UCP2) plays an important role in energy expenditure regulation. Previous studies have associated the common -866G/A (rs659366) and Ins/Del polymorphisms in the UCP2 gene with metabolic and obesity-related phenotypes. However, it is still unclear whether these polymorphisms influence weight loss after bariatric surgery.

OBJECTIVES

To investigate whether UCP2 -866G/A and Ins/Del polymorphisms are associated with weight loss outcomes after bariatric surgery.

SETTING

Longitudinal study in a university hospital.

METHODS

We retrospectively evaluated 186 patients who underwent Roux-en-Y gastric bypass (RYGB) surgery for clinical and laboratory characteristics in the preoperative period, 6, 12, and 18 months after RYGB. The -866G/A (rs659366) polymorphism was genotyped using real-time PCR, while the Ins/Del polymorphism was genotyped by direct separation of PCR products in 2.5% agarose gels.

RESULTS

Patients with the -866A/A genotype showed higher body mass index (BMI) after 6, 12, and 18 months of surgery and excess body weight after 6 and 12 months compared with G/G patients. They also showed lower excess weight loss (EWL%) after 6 and 12 months of surgery. Ins allele carriers (Ins/Ins + Ins/Del) had lower delta (Δ) BMI 12 months after surgery compared with Del/Del patients. Accordingly, patients carrying haplotypes with ≥2 risk alleles of these polymorphisms had higher BMI and excess weight and lower EWL% during follow-up.

CONCLUSION

UCP2 -866A/A genotype is associated with higher BMI and excess weight and lower EWL% during an 18-month follow-up of patients who underwent RYGB, while the Ins allele seems to be associated with lower ΔBMI 12 months after surgery. Further studies are needed to confirm the associations of the -866G/A and Ins/Del polymorphisms with weight loss after bariatric surgery.

Hypoxanthine Induces Muscular ATP Depletion and Fatigue via UCP2

Hypoxanthine (Hx), an intermediate metabolite of the purine metabolism pathway which is dramatically increased in blood and skeletal muscle during muscle contraction and metabolism, is characterized as a marker of exercise exhaustion. However, the physiological effects of Hx on skeletal muscle remain unknown. Herein, we demonstrate that chronic treatment with Hx through dietary supplementation resulted in skeletal muscle fatigue and impaired the exercise performance of mice without affecting their growth and skeletal muscle development. Hx increased the uncoupling protein 2 (UCP2) expression in the skeletal muscle, which led to decreased energy substrate storage and enhanced glycolysis. These effects could also be verified in acute treatment with Hx through intraperitoneal injection. In addition, muscular specifically knockout of UCP2 through intra-muscle tissue injection of adenovirus-associated virus reversed the effects of Hx. In conclusion, we identified a novel role of Hx in the skeletal muscular fatigue mediated by UCP2-dependent mitochondrial uncoupling. This finding may shed light on the pathological mechanism of clinical muscle dysfunctions due to abnormal metabolism, such as muscle fatigue and weakness.

Identification of Key Pathways and Genes in Obesity Using Bioinformatics Analysis and Molecular Docking Studies

Obesity is an excess accumulation of body fat. Its progression rate has remained high in recent years. Therefore, the aim of this study was to diagnose important differentially expressed genes (DEGs) associated in its development, which may be used as novel biomarkers or potential therapeutic targets for obesity. The gene expression profile of E-MTAB-6728 was downloaded from the database. After screening DEGs in each ArrayExpress dataset, we further used the robust rank aggregation method to diagnose 876 significant DEGs including 438 up regulated and 438 down regulated genes. Functional enrichment analysis was performed. These DEGs were shown to be significantly enriched in different obesity related pathways and GO functions. Then protein-protein interaction network, target genes - miRNA regulatory network and target genes - TF regulatory network were constructed and analyzed. The module analysis was performed based on the whole PPI network. We finally filtered out STAT3, CORO1C, SERPINH1, MVP, ITGB5, PCM1, SIRT1, EEF1G, PTEN and RPS2 hub genes. Hub genes were validated by ICH analysis, receiver operating curve (ROC) analysis and RT-PCR. Finally a molecular docking study was performed to find small drug molecules. The robust DEGs linked with the development of obesity were screened through the expression profile, and integrated bioinformatics analysis was conducted. Our study provides reliable molecular biomarkers for screening and diagnosis, prognosis as well as novel therapeutic targets for obesity.

Solute Carrier Transporters as Potential Targets for the Treatment of Metabolic Disease

The solute carrier (SLC) superfamily comprises more than 400 transport proteins mediating the influx and efflux of substances such as ions, nucleotides, and sugars across biological membranes. Over 80 SLC transporters have been linked to human diseases, including obesity and type 2 diabetes (T2D). This observation highlights the importance of SLCs for human (patho)physiology. Yet, only a small number of SLC proteins are validated drug targets. The most recent drug class approved for the treatment of T2D targets sodium-glucose cotransporter 2, product of the SLC5A2 gene. There is great interest in identifying other SLC transporters as potential targets for the treatment of metabolic diseases. Finding better treatments will prove essential in future years, given the enormous personal and socioeconomic burden posed by more than 500 million patients with T2D by 2040 worldwide. In this review, we summarize the evidence for SLC transporters as target structures in metabolic disease. To this end, we identified SLC13A5/sodium-coupled citrate transporter, and recent proof-of-concept studies confirm its therapeutic potential in T2D and nonalcoholic fatty liver disease. Further SLC transporters were linked in multiple genome-wide association studies to T2D or related metabolic disorders. In addition to presenting better-characterized potential therapeutic targets, we discuss the likely unnoticed link between other SLC transporters and metabolic disease. Recognition of their potential may promote research on these proteins for future medical management of human metabolic diseases such as obesity, fatty liver disease, and T2D. SIGNIFICANCE STATEMENT: Given the fact that the prevalence of human metabolic diseases such as obesity and type 2 diabetes has dramatically risen, pharmacological intervention will be a key future approach to managing their burden and reducing mortality. In this review, we present the evidence for solute carrier (SLC) genes associated with human metabolic diseases and discuss the potential of SLC transporters as therapeutic target structures.

Loss of Uncoupling Protein 3 Attenuates Western Diet-Induced Obesity, Systemic Inflammation, and Insulin Resistance in Rats

OBJECTIVE

Uncoupling protein 3 (UCP3) is a mitochondrial carrier related to fatty acid metabolism. Although gene variants of UCP3 are associated with human obesity, their contribution to increased adiposity remains unclear. This study investigated the impact that loss of UCP3 has on diet-induced obesity in rats.

METHODS

Male UCP3 knockout rats (ucp3^-/- ) and wild-type littermates (ucp3^+/+ ) were fed a high-fat, high-carbohydrate Western diet for 21 weeks. Body composition was analyzed by EchoMRI. Whole-body insulin sensitivity and rates of tissue glucose uptake were determined by using hyperinsulinemic-euglycemic clamp. Changes in tissue physiology were interrogated by microscopy and RNA sequencing.

RESULTS

Loss of UCP3 decreased fat mass gain, white adipocytes size, and systemic inflammation. The ucp3^-/- rats also exhibited preserved insulin sensitivity and increased glucose uptake in interscapular brown adipose tissue (iBAT). Brown adipocytes from ucp3^-/- rats were protected from cellular degeneration caused by lipid accumulation and from reactive oxygen species-induced protein sulfonation. Increased glutathione levels in iBAT from ucp3^-/- rats were linked to upregulation of genes encoding enzymes from the transsulfuration pathway in that tissue.

CONCLUSIONS

Loss of UCP3 partially protects rats from diet-induced obesity. This phenotype is related to induction of a compensatory antioxidant mechanism and prevention of iBAT whitening.

Potential protective effect of leptin and uncoupling protein-2 genes polymorphism in Egyptian patients with chronic kidney disease

BACKGROUND

Kidney disease is a serious public health problem worldwide. It is the fifth top-ranking cause of death in Egypt, causing approximately 3.98% of all deaths. This study's objective was to examine whether an association exists between leptin (- 2548G/A) and uncoupling protein-2 45 bp I/D genes, individually and collectively, in CKD and progression to ESRD.

METHODS

One hundred patients (69 males, 31 females) aged (47.1 ± 16.11 years) with ESRD, 40 patients (19 males, 21 females) aged (43.15 ± 10.00 years with CKD, and 50 healthy controls (23 males, 27 females) aged (37.84 ± 1.95 years) were enrolled. Polymerase chain reaction (PCR) was employed to measure variation in gene expression among the study groups. The frequency of single nucleotide polymorphisms (SNP) genotypes were identified in controls, CKD and ESRD patients.

RESULTS

Leptin genotypes were associated with lower CKD incidence in control versus study subjects (95% CI = (0.08-0.63), P = 0.01) with risk value equal to 0.22 < 1, G/A genotype was significantly lower in CKD than ESRD groups. There was no correlation between UCP-2 I/D genotype and CKD (P = 0.27). There was no correlation between the UCP-2 gene and the progression to ESRD.

CONCLUSIONS

This study suggests that, Leptin - 2548G/A gene may be a promising marker for early detection of ESRD in Egyptian patients. G/A genotype might inhibit the development of CKD to ESRD.

Vitamin D-vitamin D receptor system down-regulates expression of uncoupling proteins in brown adipocyte through interaction with Hairless protein

Our previous study showed that feeding mice with vitamin D deficiency diet markedly alleviated high-fat-diet-induced overweight, hyperinsulinemia, and hepatic lipid accumulation. Moreover, vitamin D deficiency up-regulated the expression of uncoupling protein 3 (Ucp3) in white adipose tissue (WAT) and brown adipose tissue (BAT). The present study aimed to further investigate the effects of vitamin D and vitamin D receptor (Vdr) on Ucp1–3 (Ucps) expression in brown adipocyte and the mechanism involved in it. Rat primary brown adipocytes were separated and purified. The effects of the 1,25(OH)₂D₃ (1,25-dihydroxyvitamin D3; the hormonal form of vitamin D) and Vdr system on Ucps expression in brown adipocytes were investigated in basal condition and activated condition by isoproterenol (ISO) and triiodothyronine (T3). Ucps expression levels were significantly down-regulated by 1,25(OH)₂D₃ in the activated brown adipocyte. Vdr silencing reversed the down-regulation of Ucps by 1,25(OH)₂D₃, whereas Vdr overexpression strengthened the down-regulation effects. Hairless protein did express in brown adipocyte and was localized in cell nuclei. 1,25(OH)₂D₃ increased Hairless protein expression in the cell nuclei. Hairless (Hr) silencing notably elevated Ucps expression in activated condition induced by ISO and T3. Moreover, immunoprecipitation results revealed that Vdr could interact with Hairless, which might contribute to decreasing expression of Vdr target gene Ucps. These data suggest that vitamin D suppresses expression of Ucps in brown adipocyte in a Vdr-dependent manner and the corepressor Hairless protein probably plays a role in the down-regulation.

-866G/A and Ins/Del polymorphisms in the UCP2 gene and diabetic kidney disease: case-control study and meta-analysis

Uncoupling protein 2 (UCP2) decreases reactive oxygen species (ROS). ROS overproduction is a key contributor to the pathogenesis of diabetic kidney disease (DKD). Thus, UCP2 polymorphisms are candidate risk factors for DKD; however, their associations with this complication are still inconclusive. Here, we describe a case-control study and a meta-analysis conducted to investigate the association between UCP2 -866G/A and Ins/Del polymorphisms and DKD. The case-control study comprised 385 patients with type 1 diabetes mellitus (T1DM): 223 patients without DKD and 162 with DKD. UCP2 -866G/A (rs659366) and Ins/Del polymorphisms were genotyped by real-time PCR and conventional PCR, respectively. For the meta-analysis, a literature search was conducted to identify all studies that investigated associations between UCP2 polymorphisms and DKD in patients with T1DM or type 2 diabetes mellitus. Pooled odds ratios were calculated for different inheritance models. Allele and genotype frequencies of -866G/A and Ins/Del polymorphisms did not differ between T1DM case and control groups. Haplotype frequencies were also similar between groups. Four studies plus the present one were eligible for inclusion in the meta-analysis. In agreement with case-control data, the meta-analysis results showed that the -866G/A and Ins/Del polymorphisms were not associated with DKD. In conclusion, our case-control and meta-analysis studies did not indicate an association between the analyzed UCP2 polymorphisms and DKD.

Oleoylethanolamide supplementation in obese patients newly diagnosed with non-alcoholic fatty liver disease: Effects on metabolic parameters, anthropometric indices, and expression of PPAR-α, UCP1, and UCP2 genes

The effects of oleoylethanolamide (OEA) on NAFLD are yet to be examined in human. The objective of the present study was to examine the effects of OEA supplementation along with weight loss intervention on the expression of PPAR-α, uncoupling proteins 1and 2 (UCP1 and UCP2) genes in the peripheral blood mononuclear cells (PBMCs), metabolic parameters, and anthropometric indices among obese patients with NAFLD. In this triple-blind placebo-controlled randomized clinical trial, 76 obese patients newly diagnosed with NAFLD were randomly allocated into either OEA or placebo group along with calorie-restricted diets for 12 weeks. At pre-and post-intervention phase, mRNA expression levels of PPAR-α, UCP1, and UCP2 genes in the PBMCs, serum levels of metabolic parameters as well as diet and appetite sensations were assessed. There was a significant increase in the expression levels of PPAR-α, UCP1, and UCP2 genes in the PBMCs, compared to the placebo at the endpoint. A significant decrease in the anthropometric indices, energy and carbohydrate intakes, glycemic parameters, except for hemoglobin A1c concentration was also observed in the OEA group, compared to the placebo group. OEA treatment significantly resulted in decreased serum levels of triglyceride (TG), alanine aminotransferase (ALT), aspartate aminotransferase (AST), ALT/AST, increased serum levels of high-density lipoprotein cholesterol (HDL-C), and improved appetite sensations. Importantly, a significant improvement in TG, ALT, AST, ALT/AST, HDL-C levels as well as appetite sensations by OEA were under the influence of body mass index (BMI). Although liver steatosis severity was significantly reduced in both groups, the between-group differences did not reach statistical significance (P = 0.061). In conclusion, the present study, for the first time, revealed that OEA supplementation significantly improved anthropometric and metabolic risk factors related to NAFLD.

Maya gene variants related to the risk of type 2 diabetes in a family-based association study

Mexican Maya populations have a notably high prevalence of type 2 diabetes (T2D) as a consequence of the interaction between environmental factors and a genetic component. To assess the impact of 24 single nucleotide variants (SNVs) located in 18 T2D risk genes, we conducted a family-based association evaluation in samples from Maya communities with a high incidence of the disease. A total of four hundred individuals were recruited from three Maya communities with a high T2D incidence. Family pedigrees (100) and 49 nuclear families were included. Genotyping was performed by allelic discrimination with TaqMan probes. This study also included the family-based association test (FBAT) statistic U to assess the genetic associations with T2D, and the multivariate statistical and haplotype analyses. A positive association with TD2 risk was found for WFS1 rs6446482 (p = 0.046, Z = 1.994) under an additive model, and SIRT1 rs7896005 (p = 0.038, Z = 2.073) under the dominant model. Multivariate model analysis, including T2D status, age, and body mass index (BMI), displayed significant covariance in PPARGC-1α rs8192678; SIRT1 rs7896005; TCF7L2 rs7903146 and rs122243326; UCP3 rs3781907; and HHEX rs1111875 with a P < 0.05. This study revealed an association of SIRT1 and WFS1 with T2D risk.

Association between UCP1, UCP2, and UCP3 gene polymorphisms with markers of adiposity in European adolescents: The HELENA study

AIMS

To examine the association between UCP1, UCP2, and UCP3 gene polymorphisms with adiposity markers in European adolescents and to test if there were gene interactions with objectively measured physical activity and adiposity.

METHODS

A cross-sectional study that involves 1.057 European adolescents (12-18 years old) from the Healthy Lifestyle in Europe by Nutrition in Adolescence Cross-Sectional Study. A total of 18 polymorphisms in UCP1, UCP2, and UCP3 genes were genotyped. We measured weight, height, waist, and hip circumferences and triceps and subscapular skinfold thickness. Physical activity was objectively measured by accelerometry during 7 days.

RESULTS

The C allele of the UCP1 rs6536991 polymorphism was associated with a lower risk of overweight (odds ratio [OR]: T/C + C/C vs T/T) = 0.72; 95% confidence interval [CI]: 0.53-0.98; P = 0.034; false discovery rate [FDR] = 0.048). There was a significant interaction between UCP1 rs2071415 polymorphism and physical activity with waist-to-hip ratio (P = 0.006; FDR = 0.026). Adolescents who did not meet the physical activity recommendations (less than 60 min/day of moderate to vigorous physical activity) and carrying the C/C genotype had higher waist-to-hip ratio (+ 0.067; 95% CI, 0.028-0.106; P = 0.003), while no differences across genotypes were observed in adolescents meeting the recommendations.

CONCLUSIONS

Two UCP1 polymorphisms were associated with adiposity in European adolescents. Meeting the daily physical activity recommendations may overcome the effect of the UCP1 rs2071415 polymorphism on obesity-related traits.

Important Trends in UCP3 Investigation

Membrane uncoupling protein 3 (UCP3), a member of the mitochondrial uncoupling protein family, was discovered in 1997. UCP3's properties, such as its high homology to other mitochondrial carriers, especially to UCP2, its short lifetime and low specificity of UCP3 antibodies, have hindered progress in understanding its biological function and transport mechanism over decades. The abundance of UCP3 is highest in murine brown adipose tissue (BAT, 15.0 pmol/mg protein), compared to heart (2.7 pmol/mg protein) and the gastrocnemius muscle (1.7 pmol/mg protein), but it is still 400-fold lower than the abundance of UCP1, a biomarker for BAT. Investigation of UCP3 reconstituted in planar bilayer membranes revealed that it transports protons only when activated by fatty acids (FA). Although purine nucleotides (PN) inhibit UCP3-mediated transport, the molecular mechanism differs from that of UCP1. It remains a conundrum that two homologous proton-transporting proteins exist within the same tissue. Recently, we proposed that UCP3 abundance directly correlates with the degree of FA β-oxidation in cell metabolism. Further development in this field implies that UCP3 may have dual function in transporting substrates, which have yet to be identified, alongside protons. Evaluation of the literature with respect to UCP3 is a complex task because (i) UCP3 features are often extrapolated from its "twin" UCP2 without additional proof, and (ii) the specificity of antibodies against UCP3 used in studies is rarely evaluated. In this review, we primarily focus on recent findings obtained for UCP3 in biological and biomimetic systems.

The -866G/A polymorphism in the promoter of the UCP2 gene is associated with risk for type 2 diabetes and with decreased insulin levels

BACKGROUND AND AIM

Oxidative stress and impaired insulin secretion is an underlying major risk factor for the development of type 2 diabetes (T2D). Uncoupling protein-2 (UCP2) is involved in the regulation of reactive oxygen species production, insulin secretion, and lipid metabolism. Based on this we aimed to find an association of UCP2 (G-866A) polymorphism with the risk of T2D in South Indian population.

METHODS

A total of 318 T2D patients and 312 controls were enrolled in this study. All the study subjects were genotyped for UCP2 (G-866A) polymorphism using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Fasting blood glucose, HbA1c, serum lipid profile, systolic and diastolic blood pressure were measured by standard biochemical methods. Fasting serum insulin level was measured by ELISA.

RESULTS

In UCP2 (G-866A) polymorphism, the distribution of GA (46%) and AA (14%) genotypes were significantly higher in T2D patients than the healthy controls. The frequency of GA and AA genotypes have high risk towards the development of T2D with an Odds Ratio (OR) of 1.55 (P = 0.01) and 2.04 (P = 0.01) respectively. Moreover, SNP-866 G>A allele was found to be significantly associated with T2D (OR = 1.48, P = 0.001, 95% CI = 1.16-1.88). Further, the UCP2 AA genotype showed significantly decreased level of insulin by the reduction in pancreatic β-cell function in T2D patients.

CONCLUSION

UCP2 (G-866A) polymorphism may play a crucial role in the pathogenesis of insulin secretion thus leads to the development of T2D.

The Liver in Children With Metabolic Syndrome

Non-alcoholic fatty liver disease (NAFLD) is recognized as an emerging health risk in obese children and adolescents. NAFLD represents a wide spectrum of liver conditions, ranging from asymptomatic steatosis to steatohepatitis. The growing prevalence of fatty liver disease in children is associated with an increased risk of metabolic and cardiovascular complications. NAFLD is considered the hepatic manifestation of Metabolic Syndrome (MetS) and several lines of evidence have reported that children with NAFLD present one or more features of MetS. The pathogenetic mechanisms explaining the interrelationships between fatty liver disease and MetS are not clearly understood. Altough central obesity and insulin resistance seem to represent the core of the pathophysiology in both diseases, genetic susceptibility and enviromental triggers are emerging as crucial components promoting the development of NAFLD and MetS in children. In the present review we have identified and summarizied studies discussing current pathogenetic data of the association between NAFLD and MetS in children.

Association of uncoupling protein gene polymorphisms with essential hypertension in a northeastern Han Chinese population

Uncoupling proteins (UCPs) belong to the family of mitochondrial transporter proteins and mediate regulated proton leak across the inner mitochondrial membrane. The UCPs play an important role in energy homeostasis and reactive oxygen species (ROS) release, and have been established as candidate genes for obesity, diabetes and hypertension. This study examined the possible association between the single nucleotide polymorphisms (SNPs) of UCP1-3 genes and essential hypertension (EH) in a northeastern Han Chinese population. A total of 2207 Chinese Han subjects were enrolled, including 1045 normotensives and 1162 hypertensives. Genotyping of UCP1 rs1800592, UCP1 rs12502572, UCP2 rs659366, UCP2 rs660339, and UCP3 rs3781907 was detected using Sequenom MassArray System. SHEsis was used to analyze linkage disequilibrium and haplotype. No evident association was observed between the genotype distributions and allele frequencies of individual SNPs and EH. Haplotype analysis showed the haplotype GAATA (rs1800592-rs12502572-rs659366-rs660339-rs3781907) was significantly associated with lower EH risk (p = 0.001, χ² = 10.861, OR = 0.634, 95% CI = 0.483-0.833), and AGATG was associated with increased EH risk (p = 0.012, χ² = 6.287, OR = 1.265, 95% CI = 1.052-1.521). These findings suggest haplotypes of UCP1-3 genes are linked to EH risk in a northeastern Han Chinese population. Further investigation with larger sample size in multiethnic population is needed to confirm our results.

Uncoupling proteins: Martin Klingenberg's contributions for 40 years

The uncoupling protein (UCP1) is a proton (H⁺) transporter in the mitochondrial inner membrane. By dissipating the electrochemical H⁺ gradient, UCP1 uncouples respiration from ATP synthesis, which drives an increase in substrate oxidation via the TCA cycle flux that generates more heat. The mitochondrial uncoupling-mediated non-shivering thermogenesis in brown adipose tissue is vital primarily to mammals, such as rodents and new-born humans, but more recently additional functions in adult humans have been described. UCP1 is regulated by β-adrenergic receptors through the sympathetic nervous system and at the molecular activity level by nucleotides and fatty acid to meet thermogenesis needs. The discovery of novel UCP homologs has greatly contributed to the understanding of human diseases, such as obesity and diabetes. In this article, we review the progress made towards the molecular mechanism and function of the UCPs, in particular focusing on the influential contributions from Martin Klingenberg's laboratory. Because all members of the UCP family are potentially promising drug targets, we also present and discuss possible approaches and methods for UCP-related drug discovery.

Mitochondrial metabolism in pulmonary hypertension: beyond mountains there are mountains

Pulmonary hypertension (PH) is a heterogeneous and fatal disease of the lung vasculature, where metabolic and mitochondrial dysfunction may drive pathogenesis. Similar to the Warburg effect in cancer, a shift from mitochondrial oxidation to glycolysis occurs in diseased pulmonary vessels and the right ventricle. However, appreciation of metabolic events in PH beyond the Warburg effect is only just emerging. This Review discusses molecular, translational, and clinical concepts centered on the mitochondria and highlights promising, controversial, and challenging areas of investigation. If we can move beyond the "mountains" of obstacles in this field and elucidate these fundamental tenets of pulmonary vascular metabolism, such work has the potential to usher in much-needed diagnostic and therapeutic approaches for the mitochondrial and metabolic management of PH.

Yerba Mate Stimulates Mitochondrial Biogenesis and Thermogenesis in High-Fat-Diet-Induced Obese Mice

SCOPE

The potential effects of yerba mate (YM) on mitochondrial biogenesis and thermogenesis are evaluated.

METHODS AND RESULTS

The in vitro effects of YM on mitochondrial respiration are assessed in C2C12 cells. The expression of genes related to mitochondrial biogenesis and thermogenesis are analyzed by quantitative PCR. The in vivo experiments are performed on mice fed a high-fat diet (HFD) and treated with YM extract. Indirect calorimetry was performed, and the expression of genes and proteins related to mitochondrial biogenesis, thermogenesis, and de novo lipogenesis is determined by quantitative PCR and western blot. Our in vitro data indicate that YM increases mtDNA copy number as well as mitochondrial spare respiratory capacity and coupling efficiency. The gene expression profile reinforces this evidence, indicating a modulation of genes downstream of Ampk. In vivo, it is found that YM partially prevents diet-induced obesity by increasing energy expenditure and enhancing mitochondrial biogenesis via the AMPK/SIRT1/PGC1α pathway.

CONCLUSIONS

YM stimulates mitochondriogenesis and Ucp expression, leading to an increase in the spare respiratory capacity and energy dissipation. These effects may help to better understand the potential use of YM for obesity treatment.

Polymorphisms in the uncoupling protein 3 gene and their associations with feed efficiency in chickens

Objective

The uncoupling protein 3 (UCP3) is a member of the mitochondrial anion carrier superfamily and has crucial effects on growth and feed efficiency in many species. Therefore, the objective of the present study was to examine the association of polymorphisms in the UCP3 gene with feed efficiency in meat-type chickens.

Methods

Six single nucleotide polymorphisms (SNPs) of the UCP3 gene were chosen to be genotyped using matrix-assisted laser desorption-ionization time-of-flight mass spectrometry in meat-type chicken populations with 724 birds in total. Body weight at 49 (BW49) and 70 days of age (BW70) and feed intake (FI) in the interval were collected, then body weight gain (BWG) and feed conversion ratio (FCR) were calculated individually.

Results

One SNP with a low minor allele frequency (<1%) was removed by quality control and data filtering. The results showed that rs13997809 of UCP3 was significantly associated with BWG and FCR (p<0.05), and that rs13997811 had significant effects on BW70 and BWG (p<0.05). Rs13997812 of UCP3 was strongly associated with BW70, FI, and FCR (p<0.05). Furthermore, individuals with AA genotype of rs13997809 had significantly higher BWG and lower FCR (p<0.05) than those with AT genotype. The GG individuals showed strongly higher BW70 and BWG than AA birds in rs13997811 (p<0.05). Birds with the TT genotype of rs13997812 had significantly greater BW70 and lower FCR compared with the CT birds (p<0.05). In addition, the TAC haplotype based on rs13997809, rs13997811, and rs13997812 showed significant effects on BW70, FI, and FCR (p<0.05).

Conclusion

Our results therefore demonstrate important roles for UCP3 polymorphisms in growth and feed efficiency that might be used in meat-type chicken breeding programs.

The UCP2 -866G/A, Ala55Val and UCP3 -55C/T polymorphisms are associated with premature coronary artery disease and cardiovascular risk factors in Mexican population

We examined the role of UCP gene polymorphisms as susceptibility markers for premature coronary artery disease (pCAD). The UCP2 Ala55Val (C/T rs660339), UCP2 -866G/A (rs659366), and UCP3 -55C/T (rs1800849) polymorphisms were genotyped in 948 patients with pCAD, and 763 controls. The distribution of the UCP2 A55V (C/T rs660339) and UCP3 -55 (rs1800849) was similar in patients and controls. However, under a recessive model, the UCP2 -866 (rs659366) A allele was associated with increased risk of developing pCAD (OR = 1.43, Pc = 0.003). On the other hand, patients with pCAD and UCP2 A55V (rs660339) TT showed high levels of visceral abdominal fat (VAF) (Pc = 0.002), low levels of subcutaneous abdominal fat (SAF) (Pc = 0.001) and high VAT/SAT ratio (Pc < 0.001). Also, patients with UCP2 -866 (rs659366) AA showed increased levels of VAF (Pc = 0.003), low levels of SAF (Pc = 0.001) and a high VAT/SAT ratio (Pc = 0.002), whereas patients with the UCP3 -55 (rs1800849) TT presented high levels of VAF (Pc = 0.002). The results suggest the association of the UCP2 -866 (rs659366) polymorphism with risk of developing pCAD. Some polymorphisms were associated with abdominal fat levels and cardiovascular risk factors.

Response of skeletal muscle UCP2-expression during metabolic adaptation to caloric restriction

BACKGROUND/OBJECTIVES

Spendthrift vs. thrifty individuals expend more energy and experience greater weight loss during caloric restriction (CR). Adaptive mechanisms in skeletal muscle, adipose tissue, and on hormone level modulate energy expenditure (EE) during weight loss. Metabolic mechanisms underlying the variability in EE during CR are unclear. The present study explored whether during long-term CR (i) gene expression changes in skeletal muscle and adipose tissue relate with the individual EE response and weight loss, and (ii) altered catecholamine and FGF21-concentrations are associated with measures of metabolic adaptation.

SUBJECTS/METHODS

In a 10-week inpatient study, 24-h EE was measured before and after 6 weeks of 50% CR in 12 subjects using whole-room indirect calorimetry. Weight loss was assessed and repeated hormone measurements performed. Muscle and adipose tissue biopsies were taken before and after CR, and gene expression was assessed (RNA-Seq). Genes showing the most significant changes after CR were tested for association with EE and followed-up for further association with metabolic measures in a separate phenotyping study (n = 103).

RESULTS

Muscle UCP2 showed the strongest change after CR (log₂-fold change = -1.57, false discovery rate = 0.10) and was considered the best gene for exploration of metabolic adaptive processes. A greater decrease in UCP2-expression was associated with less weight loss (P = 0.03, r = 0.77) and relatively lower 24-h EE after CR (P = 0.001, r = -0.96). Post-CR changes in FGF21-plasma concentrations correlated with UCP2-expression change (P = 0.02, r = -0.89) and weight loss (P = 0.003, r = -0.83). In a separate metabolic phenotyping study, muscle UCP2-expression correlated with respiratory quotient and macronutrient oxidation. In adipose tissue, no candidate genes for metabolic exploration were found.

CONCLUSIONS

Changes in muscle UCP2-expression reflect an inter-individual metabolic response to long-term CR and may influence EE and weight loss via modulation of substrate oxidation.

mRNA m6A plays opposite role in regulating UCP2 and PNPLA2 protein expression in adipocytes

BACKGROUND/OBJECTIVE

N⁶-methyladenosine (m⁶A) modification of mRNA plays an important role in regulating adipogenesis. However, its underlying mechanism remains largely unknown.

SUBJECTS/METHODS

Using Jinhua and Landrace pigs as fat and lean models, we presented a comprehensive transcriptome-wide m⁶A profiling in adipose tissues from these two pig breeds. Two differentially methylated genes were selected to explore the mechanisms of m⁶A-mediated regulation of gene function.

RESULTS

The ratio of m⁶A/A in the layer of backfat (LB) was significantly higher in Landrace than that in Jinhua. Transcriptome-wide m⁶A profiling revealed that m⁶A modification on mRNA occurs in the conserved sequence motif of RRACH and that the pig transcriptome contains 0.53-0.91 peak per actively expressed transcript. The relative density of m⁶A peaks in the 3'UTR were higher than in 5'UTR. Genes with common m⁶A peaks from both Landrace (L-LB) and Jinhua (J-LB) were enriched in RNA splicing and cellular lipid metabolic process. The unique m⁶A peak genes (UMGs) from L-LB were mainly enriched in the extracellular matrix (ECM) and collagen catabolic process, whereas the UMGs from J-LB are mainly involved in RNA splicing, etc. Lipid metabolism processes were not significantly enriched in the UMGs from L-LB or J-LB. Uncoupling protein-2 (UCP2) and patatin-like phospholipase domain containing 2 (PNPLA2) were two of the UMGs in L-LB. Synonymous mutations (MUT) were conducted to reduce m⁶A level of UCP2 and PNPLA2 mRNAs. Adipogenesis test showed that UCP2-MUT further inhibited adipogenesis, while PNPLA2-MUT promoted lipid accumulation compared with UCP2-WT and PNPLA2-WT, respectively. Further study showed m⁶A negatively mediates UCP2 protein expression and positively mediates PNPLA2 protein expression. m⁶A modification affects the translation of PNPLA2 most likely through YTHDF1, whereas UCP2 is likely neither the target of YTHDF2 nor the target of YTHDF1.

CONCLUSION

Our data demonstrated a conserved and yet dynamically regulated m⁶A methylome in pig transcriptomes and provided an important resource for studying the function of m⁶A epitranscriptomic modification in obesity development.

Uncoupling Protein 2 and Peroxisome Proliferator-Activated Receptor γ Gene Polymorphisms in Association with Diabetes Susceptibility in Chinese Han Population with Variant Glucose Tolerance

OBJECTIVE

To investigate the association of polymorphisms in uncoupling protein 2 (UCP2) and peroxisome proliferator-activated receptor (PPARγ) with glucolipid metabolism in Chinese Han population.

METHODS

Five hundred eighty-nine subjects were divided into normal glucose tolerance (NGT) group (n = 198) and abnormal glucose tolerance group (n = 358). HbA1c, blood lipid profile, plasma glucose, and insulin were determined. Insulin sensitivity (HOMA-IR and Matsuda index (ISI_M)) and insulin secretion indexes (HOMA-β, early and total phase disposition index) were evaluated. Eight potential functional SNPs in UCP2 and 7 in PPARγ were selected. SNPs were genotyped on Sequenom MassARRAY platform.

RESULTS

The GG genotype of rs2920502 in PPARγ was associated with decreased risk of impaired glucose tolerance (G allele: OR: 0.818, 95%CI: 0.526-0.969, P = 0.042; GG: OR: 0.715, 95%CI: 0.527-0.97, P = 0.031). The TT genotype of rs3856806 in PPARγ was associated with increased risk of impaired glucose tolerance (T allele: OR: 1.46, 95%CI: 1.055-2.017, P = 0.022; TT: OR: 1.58, 95%CI: 1.104-2.761, P = 0.032). The GG genotype of rs2920502 in PPARγ had better blood glucose and increased insulin secretion and had lower HOMA-IR than GC/CC genotypes.

CONCLUSION

It probably could prevent insulin resistance in early stage by classifying the genotype of rs649446 and rs7109266 in UCP2. The GG genotype of rs2920502 in PPARγ had a decreased risk for diabetes. The TT genotype of rs3856806 in PPARγ had an increased risk for diabetes.

The association of insertions/deletions (INDELs) and variable number tandem repeats (VNTRs) with obesity and its related traits and complications

BACKGROUND

Despite the fact that insertions/deletions (INDELs) are the second most common type of genetic variations and variable number tandem repeats (VNTRs) represent a large portion of the human genome, they have received far less attention than single nucleotide polymorphisms (SNPs) and larger forms of structural variation like copy number variations (CNVs), especially in genome-wide association studies (GWAS) of complex diseases like polygenic obesity. This is exemplified by the vast amount of review papers on the role of SNPs and CNVs in obesity, its related traits (like anthropometric measurements, biochemical variables, and eating behavior), and its related complications (like hypertension, hypertriglyceridemia, hypercholesterolemia, and insulin resistance-collectively known as metabolic syndrome). Hence, this paper reviews the types of INDELs and VNTRs that have been studied for association with obesity and its related traits and complications. These INDELs and VNTRs could be found in the obesity loci or genes from the earliest GWAS and candidate gene association studies, like FTO, genes in the leptin-proopiomelanocortin pathway, and UCP2/3. Given the important role of the brain serotonergic and dopaminergic reward system in obesity susceptibility, the association of INDELs and VNTRs in these neurotransmitters' metabolism and transport genes with obesity is also reviewed. Next, the role of INS VNTR in obesity and its related traits is questionable, since recent large-scale studies failed to replicate the earlier positive associations. As obesity results in chronic low-grade inflammation of the adipose tissue, the proinflammatory cytokine gene IL1RA and anti-inflammatory cytokine gene IL4 have VNTRs that are implicated in obesity. A systemic proinflammatory state in combination with activation of the renin-angiotensin system and decreased nitric oxide bioavailability as found in obesity leads to endothelial dysfunction. This explains why VNTR and INDEL in eNOS and ACE, respectively, could be predisposing factors of obesity. Finally, two novel genes, DOCK5 and PER3, which are involved in the regulation of the Akt/MAPK pathway and circadian rhythm, respectively, have VNTRs and INDEL that might be associated with obesity.

SHORT CONCLUSION

In conclusion, INDELs and VNTRs could have important functional consequences in the pathophysiology of obesity, and research on them should be continued to facilitate obesity prediction, prevention, and treatment.

The Slo(w) path to identifying the mitochondrial channels responsible for ischemic protection

Mitochondria play an important role in tissue ischemia and reperfusion (IR) injury, with energetic failure and the opening of the mitochondrial permeability transition pore being the major causes of IR-induced cell death. Thus, mitochondria are an appropriate focus for strategies to protect against IR injury. Two widely studied paradigms of IR protection, particularly in the field of cardiac IR, are ischemic preconditioning (IPC) and volatile anesthetic preconditioning (APC). While the molecular mechanisms recruited by these protective paradigms are not fully elucidated, a commonality is the involvement of mitochondrial K⁺ channel opening. In the case of IPC, research has focused on a mitochondrial ATP-sensitive K⁺ channel (mitoK_ATP), but, despite recent progress, the molecular identity of this channel remains a subject of contention. In the case of APC, early research suggested the existence of a mitochondrial large-conductance K⁺ (BK, big conductance of potassium) channel encoded by the Kcnma1 gene, although more recent work has shown that the channel that underlies APC is in fact encoded by Kcnt2 In this review, we discuss both the pharmacologic and genetic evidence for the existence and identity of mitochondrial K⁺ channels, and the role of these channels both in IR protection and in regulating normal mitochondrial function.

Emerging Metabolic Therapies in Pulmonary Arterial Hypertension

Pulmonary hypertension (PH) is an enigmatic vascular disorder characterized by pulmonary vascular remodeling and increased pulmonary vascular resistance, ultimately resulting in pressure overload, dysfunction, and failure of the right ventricle. Current medications for PH do not reverse or prevent disease progression, and current diagnostic strategies are suboptimal for detecting early-stage disease. Thus, there is a substantial need to develop new diagnostics and therapies that target the molecular origins of PH. Emerging investigations have defined metabolic aberrations as fundamental and early components of disease manifestation in both pulmonary vasculature and the right ventricle. As such, the elucidation of metabolic dysregulation in pulmonary hypertension allows for greater therapeutic insight into preventing, halting, or even reversing disease progression. This review will aim to discuss (1) the reprogramming and dysregulation of metabolic pathways in pulmonary hypertension; (2) the emerging therapeutic interventions targeting these metabolic pathways; and (3) further innovation needed to overcome barriers in the treatment of this devastating disease.