SOD3 Is Secreted by Adipocytes and Mitigates High-Fat Diet-Induced Obesity, Inflammation, and Insulin Resistance

The identification of key genes and pathways in polycystic ovary syndrome by bioinformatics analysis of next-generation sequencing data

Background

Polycystic ovary syndrome (PCOS) is a reproductive endocrine disorder. The specific molecular mechanism of PCOS remains unclear. The aim of this study was to apply a bioinformatics approach to reveal related pathways or genes involved in the development of PCOS.

Methods

The next-generation sequencing (NGS) dataset GSE199225 was downloaded from the gene expression omnibus (GEO) database and NGS dataset analyzed is obtained from in vitro culture of PCOS patients’ muscle cells and muscle cells of healthy lean control women. Differentially expressed gene (DEG) analysis was performed using DESeq2. The g:Profiler was utilized to analyze the gene ontology (GO) and REACTOME pathways of the differentially expressed genes. A protein–protein interaction (PPI) network was constructed and module analysis was performed using HiPPIE and cytoscape. The miRNA-hub gene regulatory network and TF-hub gene regulatory network were constructed. The hub genes were validated by using receiver operating characteristic (ROC) curve analysis.

Results

We have identified 957 DEG in total, including 478 upregulated genes and 479 downregulated gene. GO terms and REACTOME pathways illustrated that DEG were significantly enriched in regulation of molecular function, developmental process, interferon signaling and platelet activation, signaling, and aggregation. The top 5 upregulated hub genes including HSPA5, PLK1, RIN3, DBN1, and CCDC85B and top 5 downregulated hub genes including DISC1, AR, MTUS2, LYN, and TCF4 might be associated with PCOS. The hub gens of HSPA5 and KMT2A, together with corresponding predicted miRNAs (e.g., hsa-mir-34b-5p and hsa-mir-378a-5p), and HSPA5 and TCF4 together with corresponding predicted TF (e.g., RCOR3 and TEAD4) were found to be significantly correlated with PCOS.

Conclusions

These study uses of bioinformatics analysis of NGS data to obtain hub genes and key signaling pathways related to PCOS and its associated complications. Also provides novel ideas for finding biomarkers and treatment methods for PCOS and its associated complications.

Nuclear Factor Erythroid 2 Related Factor 2 and Mitochondria Form a Mutually Regulating Circuit in the Prevention and Treatment of Metabolic Syndrome

Significance: Metabolic syndrome (MetS) has become a major global public health problem and there is an urgent need to elucidate its pathogenesis and find more effective targets and modalities for intervention. Recent Advances: Oxidative stress and inflammation are two of the major causes of MetS-related symptoms such as insulin resistance and obesity. Nuclear factor erythroid 2 related factor 2 (Nrf2) is one of the important systems responding to oxidative stress and inflammation. As cells undergo stress, cysteines within Kelch-like ECH-associated protein 1 (Keap1) are oxidized or electrophilically modified, allowing Nrf2 to escape ubiquitination and be translocated from the cytoplasm to the nucleus, facilitating the initiation of the antioxidant transcriptional program. Meanwhile, a growing body of evidence points out a specific modulation of mitochondrial homeostasis by Nrf2. After nuclear translocation, Nrf2 activates downstream genes involved in various aspects of mitochondrial homeostasis, including mitochondrial biogenesis and dynamics, mitophagy, aerobic respiration, and energy metabolism. In turn, mitochondria reciprocally activate Nrf2 by releasing reactive oxygen species and regulating antioxidant enzymes. Critical Issues: In this review, we first summarize the interactions between Nrf2 and mitochondria in the modulation of oxidative stress and inflammation to ameliorate MetS, then propose that Nrf2 and mitochondria form a mutually regulating circuit critical to maintaining homeostasis during MetS. Future Directions: Targeting the Nrf2-mitochondrial circuit may be a promising strategy to ameliorate MetS, such as obesity, diabetes, and cardiovascular diseases.

Exploration of SOD3 from gene to therapeutic prospects: a brief review

Superoxide dismutase 3 (SOD3) is a type of antioxidant enzyme, which plays an important role in converting superoxide anion into hydrogen peroxide through its extracellular activity. This enzyme has been widely studied and evaluated from various points of view, including maintaining cellular redox balance, protecting against oxidative damage, and enhancing overall cellular resilience. The current paper focuses on SOD3 expression from a functional perspective. In addition to a detailed examination of the gene and protein structure, we found ample evidence indicating that the expression level of SOD3 undergoes alterations in response to various transcription factors, signaling pathways, and diverse conditions. These fluctuations, by disrupting the homeostasis of SOD3, can serve as crucial indicators of the onset or exacerbation of specific diseases. In this regard, significant efforts have been dedicated in recent years to the treatment of diseases through the regulation of SOD3 expression. The ultimate goal of this review is to extensively highlight and demonstrate the immense potential of SOD3 as a therapeutic target, emphasizing its profound impact on health outcomes.

SOD3 regulates FLT1 to affect bone metabolism by promoting osteogenesis and inhibiting adipogenesis through PI3K/AKT and MAPK pathways

Osteoporosis is a chronic disease that seriously affects the quality of life and longevity of the elderly, so exploring the mechanism of osteoporosis is crucial for drug development and treatment. Bone marrow mesenchymal stem cells are stem cells with multiple differentiation potentials in bone marrow, and changing their differentiation direction can change bone mass. As an extracellular superoxide dismutase, Superoxide Dismutase 3 (SOD3) has been proved to play an important role in multiple organs, but the detailed mechanism of action in bone metabolism is still unclear. In this study, the results of clinical serum samples ELISA and single cell sequencing chip analysis proved that the expression of SOD3 was positively correlated with bone mass, and SOD3 was mainly expressed in osteoblasts and adipocytes and rarely expressed in osteoblasts in BMSCs. In vitro experiments showed that SOD3 can promote osteogenesis and inhibit adipogenesis. Compared with WT mice, the mice that were knocked out of SOD3 had a significant decrease in bone mineral density and significant changes in related parameters. The results of HE and IHC staining suggested that knocking out SOD3 would lead to fat accumulation in the bone marrow cavity and weakened osteogenesis. Both in vitro and in vivo experiments indicated that SOD3 affects bone metabolism by promoting osteogenesis and inhibiting adipogenesis. The results of transcriptome sequencing and revalidation showed that SOD3 can affect the expression of FLT1. Through in vitro experiments, we proved that FLT1 can also promote osteogenesis and inhibit adipogenesis. In addition, through the repeated experiments, the interaction between the two molecules (SOD3 and FLT1) was verified again. Finally, it was verified by WB that SOD3 regulates FLT1 to affect bone metabolism through PI3K/AKT and MAPK pathways.

Genetic deletion of MMP12 ameliorates cardiometabolic disease by improving insulin sensitivity, systemic inflammation, and atherosclerotic features in mice

BACKGROUND

Matrix metalloproteinase 12 (MMP12) is a macrophage-secreted protein that is massively upregulated as a pro-inflammatory factor in metabolic and vascular tissues of mice and humans suffering from cardiometabolic diseases (CMDs). However, the molecular mechanisms explaining the contributions of MMP12 to CMDs are still unclear.

METHODS

We investigated the impact of MMP12 deficiency on CMDs in a mouse model that mimics human disease by simultaneously developing adipose tissue inflammation, insulin resistance, and atherosclerosis. To this end, we generated and characterized low-density lipoprotein receptor (Ldlr)/Mmp12-double knockout (DKO) mice fed a high-fat sucrose- and cholesterol-enriched diet for 16-20 weeks.

RESULTS

DKO mice showed lower cholesterol and plasma glucose concentrations and improved insulin sensitivity compared with LdlrKO mice. Untargeted proteomic analyses of epididymal white adipose tissue revealed that inflammation- and fibrosis-related pathways were downregulated in DKO mice. In addition, genetic deletion of MMP12 led to alterations in immune cell composition and a reduction in plasma monocyte chemoattractant protein-1 in peripheral blood which indicated decreased low-grade systemic inflammation. Aortic en face analyses and staining of aortic valve sections demonstrated reduced atherosclerotic plaque size and collagen content, which was paralleled by an improved relaxation pattern and endothelial function of the aortic rings and more elastic aortic sections in DKO compared to LdlrKO mice. Shotgun proteomics revealed upregulation of anti-inflammatory and atheroprotective markers in the aortas of DKO mice, further supporting our data. In humans, MMP12 serum concentrations were only weakly associated with clinical and laboratory indicators of CMDs.

CONCLUSION

We conclude that the genetic deletion of MMP12 ameliorates obesity-induced low-grade inflammation, white adipose tissue dysfunction, biomechanical properties of the aorta, and the development of atherosclerosis. Therefore, therapeutic strategies targeting MMP12 may represent a promising approach to combat CMDs.

Extracellular Superoxide Dismutase Attenuates Hepatic Oxidative Stress in Nonalcoholic Fatty Liver Disease through the Adenosine Monophosphate-Activated Protein Kinase Activation

Oxidative stress is key in type 2 diabetes-associated nonalcoholic fatty liver disease (NAFLD). We explored whether extracellular superoxide dismutase (EC-SOD) activates adenosine monophosphate-activated protein kinase (AMPK) to enhance antioxidant synthesis and lipid metabolism in NAFLD. Human recombinant EC-SOD (hEC-SOD) was administered to 8-week-old male C57BLKS/J db/db mice through intraperitoneal injection once a week for 8 weeks. Target molecules involved in oxidative stress and lipid metabolism were investigated. hEC-SOD improved insulin resistance and systemic and hepatic oxidative stress characterized by increases in urinary 8-hydroxy-deoxyguanosine and 8-isoprostane levels in db/db mice and a decrease in DHE expression in the liver, respectively. Hepatic SOD3 expression in db/db mice was reversed by hEC-SOD, which improved hepatic steatosis, inflammation with M2 polarization, apoptosis, autophagy, fibrosis and lipid metabolism in db/db mice, as reflected by the changes in serum and hepatic markers, monocyte chemoattractant protein-1, tumor necrosis factor-α, TUNEL-positive cells, Bcl-2/BAX ratio, beclin1 and LC3-II/LC3-1. At the molecular level, hEC-SOD increased phosphorylated-AMPK related to CaMKKß, activation of peroxisome proliferative-activated receptor-gamma coactivator (PGC)-1α and dephosphorylation of forkhead box O (FoxO)1 and their subsequent downstream signaling. In HepG2Cs cells using AMPKα1 and AMPKα2 siRNA, hEC-SOD demonstrated a protective effect via the direct activation of both AMPK-PGC-1α and AMPK-FoxO1. EC-SOD might be a potential therapeutic agent for NAFLD through the activation of AMPK-PGC-1α and AMPK-FoxO1 signaling in hepatocytes, which modulates lipid metabolism, leading to anti-inflammatory, antioxidative and antiapoptotic effects and improving autophagy in the liver.

Effects of dietary adjustment of n-3:n-6 fatty-acid ratio to 1:2 on anti-inflammatory and insulin-signaling pathways in ovariectomized mice with high fat diet-induced obesity

Estrogen deficiency increases the secretion of inflammatory mediators and can lead to obesity. Consequently, estrogen deficiency can cause metabolic syndrome, particularly insulin resistance during menopause. Both fish oil and perilla oil contain n-3 fatty acids, which may regulate several inflammatory cytokines. Additionally, adjusting the dietary n-3:n-6 fatty-acid ratio to 1:2 may help treat or prevent chronic diseases. Therefore, we investigated the effect of anti-inflammatory and insulin-signaling pathways, not solely in relation to the (n-3:n-6 fatty-acid ratio at 1:2), but also considering the origin of n-3 fatty acids found in fish oil and perilla oil, in a mouse model of estrogen deficiency induced by ovariectomy and obesity induced by a high-fat diet (HFD). Female C57BL/6J mice were divided into five groups: sham mice on a normal diet; ovariectomized (OVX) mice on a normal diet (OC); OVX mice on a HFD plus lard oil (OL), fish oil (OF), or perilla oil (OP). The dietary n-3:n-6 ratio in the OF and OP groups was adjusted to 1:2. The results showed OF group exhibited significantly lower abdominal adipose tissue weight, fewer liver lipid droplets, and smaller uterine adipocytes, compared with the OL group. Compared with the OL group, the OF and OP groups exhibited higher oral glucose tolerance and lower serum alanine aminotransferase activity, triacylglycerol levels, and total cholesterol levels. Hepatic JAK2, STAT3, and SOCS3 mRNA expression and p-NF-κB p65 and IL-6 levels were significantly lower in the OF and OP groups than in the OL group. Only the OF group exhibited an increase in PI3K and Akt mRNA expression, decrease in GLUT2 mRNA expression, and considerable elevation of p-Akt. Both fish and perilla oil reduced inflammatory signaling markers. However, only fish oil improved insulin signaling (PI3K, Akt, and GLUT2). Our data suggest that fish oil can alleviate insulin signaling through activating the PI3K-Akt-GLUT2 cascade signaling pathway.

The Applications and Mechanisms of Superoxide Dismutase in Medicine, Food, and Cosmetics

Superoxide dismutase (SOD) is a class of enzymes that restrict the biological oxidant cluster enzyme system in the body, which can effectively respond to cellular oxidative stress, lipid metabolism, inflammation, and oxidation. Published studies have shown that SOD enzymes (SODs) could maintain a dynamic balance between the production and scavenging of biological oxidants in the body and prevent the toxic effects of free radicals, and have been shown to be effective in anti-tumor, anti-radiation, and anti-aging studies. This research summarizes the types, biological functions, and regulatory mechanisms of SODs, as well as their applications in medicine, food production, and cosmetic production. SODs have proven to be a useful tool in fighting disease, and mimetics and conjugates that report SODs have been developed successively to improve the effectiveness of SODs. There are still obstacles to solving the membrane permeability of SODs and the persistence of enzyme action, which is still a hot spot and difficulty in mining the effect of SODs and promoting their application in the future.

Cross-tissue omics analysis discovers ten adipose genes encoding secreted proteins in obesity-related non-alcoholic fatty liver disease

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is a fast-growing, underdiagnosed, epidemic. We hypothesise that obesity-related inflammation compromises adipose tissue functions, preventing efficient fat storage, and thus driving ectopic fat accumulation into the liver.

METHODS

To identify adipose-based mechanisms and potential serum biomarker candidates (SBCs) for NAFLD, we utilise dual-tissue RNA-sequencing (RNA-seq) data in adipose tissue and liver, paired with histology-based NAFLD diagnosis, from the same individuals in a cohort of obese individuals. We first scan for genes that are differentially expressed (DE) for NAFLD in obese individuals' subcutaneous adipose tissue but not in their liver; encode proteins secreted to serum; and show preferential adipose expression. Then the identified genes are filtered to key adipose-origin NAFLD genes by best subset analysis, knockdown experiments during human preadipocyte differentiation, recombinant protein treatment experiments in human liver HepG2 cells, and genetic analysis.

FINDINGS

We discover a set of genes, including 10 SBCs, that may modulate NAFLD pathogenesis by impacting adipose tissue function. Based on best subset analysis, we further follow-up on two SBCs CCDC80 and SOD3 by knockdown in human preadipocytes and subsequent differentiation experiments, which show that they modulate crucial adipogenesis genes, LPL, SREBPF1, and LEP. We also show that treatment of the liver HepG2 cells with the CCDC80 and SOD3 recombinant proteins impacts genes related to steatosis and lipid processing, including PPARA, NFE2L2, and RNF128. Finally, utilizing the adipose NAFLD DE gene cis-regulatory variants associated with serum triglycerides (TGs) in extensive genome-wide association studies (GWASs), we demonstrate a unidirectional effect of serum TGs on NAFLD with Mendelian Randomization (MR) analysis. We also demonstrate that a single SNP regulating one of the SBC genes, rs2845885, produces a significant MR result by itself. This supports the conclusion that genetically regulated adipose expression of the NAFLD DE genes may contribute to NAFLD through changes in serum TG levels.

INTERPRETATION

Our results from the dual-tissue transcriptomics screening improve the understanding of obesity-related NAFLD by providing a targeted set of 10 adipose tissue-active genes as new serum biomarker candidates for the currently grossly underdiagnosed fatty liver disease.

FUNDING

The work was supported by NIH grants R01HG010505 and R01DK132775. The Genotype-Tissue Expression (GTEx) Project was supported by the Common Fund of the Office of the Director of the National Institutes of Health, and by NCI, NHGRI, NHLBI, NIDA, NIMH, and NINDS. The KOBS study (J. P.) was supported by the Finnish Diabetes Research Foundation, Kuopio University Hospital Project grant (EVO/VTR grants 2005-2019), and the Academy of Finland grant (Contract no. 138006). This study was funded by the European Research Council under the European Union's Horizon 2020 research and innovation program (Grant No. 802825 to M. U. K.). K. H. P. was funded by the Academy of Finland (grant numbers 272376, 266286, 314383, and 335443), the Finnish Medical Foundation, Gyllenberg Foundation, Novo Nordisk Foundation (grant numbers NNF10OC1013354, NNF17OC0027232, and NNF20OC0060547), Finnish Diabetes Research Foundation, Finnish Foundation for Cardiovascular Research, University of Helsinki, and Helsinki University Hospital and Government Research Funds. I. S. was funded by the Instrumentarium Science Foundation. Personal grants to U. T. A. were received from the Matti and Vappu Maukonen Foundation, Ella och Georg Ehrnrooths Stiftelse and the Finnish Foundation for Cardiovascular Research.

Circular RNA 0010117 promotes aggressive glioblastoma behavior by regulating the miRNA-6779-5p/SPEN axis

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Circ-0010117 is down-regulated in glioblastoma.

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Circ-0010117 regulates aggressiveness via miRNA-6779-5p in glioblastoma.

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SPEN contributed to regulate miRNA-6779-5p in glioblastoma.

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Upregulated Circ-0010117 inhibited in vivo tumor growth of human glioblastoma xenograft.

Noncoding RNAs (ncRNAs) play important roles in cancer biology, providing potential targets for cancer intervention. As a new class of endogenous noncoding RNAs, circular RNAs (circRNAs) have been recently identified in cell development and function, and certain types of pathological responses contribute to cancer progression, including glioblastoma. However, the potential mechanisms underlying the relationship between circRNAs and glioblastoma progression are still largely unknown. Methods: The expression and roles of circular RNA 0010117 (circ-0010117) were examined in vitro and in vivo. Quantitative RT‒PCR and western blotting were used to measure the expression of circRNA, miRNA, each gene, or related proteins. Cell biology experiments were performed to detect the biological function of circ-0010117 in glioblastoma cell lines. Moreover, bioinformatics analysis, luciferase reporter assays, and functional complementation analysis were carried out to investigate the target genes. Tumorigenesis was also evaluated by xenografting cells into nude mice. In this study, we found that circ-0010117 is downregulated in glioblastoma compared with corresponding paratumoural tissues. Subsequently, we observed that circ-0010117 can regulate aggressiveness in glioblastoma cells through miR-6779-5p. Furthermore, SPEN was verified as a direct target of miR-6779-5p and contributes to the circ-0010117 regulatory network. In addition, we identified that overexpression of circ-0010117 can suppress tumorigenesis in nude mice. Our findings indicate that circular RNA 0010117 promotes the aggressive behavior of glioblastoma by regulating the miRNA-6779-5p/SPEN axis. Our results provide a rationale for the use of circ-0010117 as a novel potential therapeutic target in glioblastoma.

Anemarrhena saponins attenuate insulin resistance in rats with high-fat diet-induced obesity via the IRS-1/PI3K/AKT pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Anemarrhena asphodeloides is the dry rhizome of Anemarrhena asphodeloides Bge. Anemarrhena Saponins isolated from Anemarrhena asphodeloides are one of the pharmacologically active components of this plant and have blood lipid reduction and blood glucose reduction properties. These facts suggest that these saponins might be helpful in the treatment of insulin resistance.

AIM OF THE STUDY

To determine the therapeutic effect of anemarrhena saponins on insulin resistance and the probable underlying mechanism.

MATERIALS AND METHODS

Insulin-resistant rats were used as the experimental subject, to observe the therapeutic effect of anemarrhena saponins. The blood glucose and blood lipid parameters were determined using the relevant kits. We used hematoxylin and eosin (H&E) staining to observe the protective effect of anemarrhena saponins on the livers of insulin-resistant rats and reverser transcripition polymerase chain reaction (RT-PCR) to analyze the mRNA expressions patterns of genes related to glucose metabolism and inflammatory factors. The toxicity of anemarrhena saponins to HepG2 cells was calculated using the MTT assay. Further, we conducted in vivo and in vitro experiments, and Western-blot analysis to study the effects of anemarrhena saponins on the IRS-1/PI3K/AKT pathway.

RESULTS

Anemarrhena saponins were found to improve dyslipidemia, reduce obesity and inflammation, and alleviate liver injury in insulin-resistant rats. Anemarrhena saponins also reduced the mRNA expression of gluconeogenesis-related genes sunch as G6pase, PEPCK, and GSK3β in the liver. Moreover, anemarrhena saponins up-regulated the phosphorylation levels of IRS-1, PI3K and AKT, promoted insulin signal transduction, and reduced liver injury induced by insulin resistance.

CONCLUSIONS

These findings suggest that anemarrhena saponins could promote insulin signal transduction through the IRS-1/PI3K/AKT pathway, thereby reducing the damage caused by insulin resistance.

Association among extracellular superoxide dismutase genotype, plasma concentration, and comorbidity in the very old and centenarians

Superoxide dismutase 3 (SOD3), an antioxidant enzyme, is known as extracellular SOD (EC-SOD) because it is the predominant form in extracellular fluids. The diversity of plasma EC-SOD concentration is associated with the SOD3 p.R231G missense variant genotype. To clarify the association among SOD3 genotype, plasma EC-SOD concentration, and comorbidity in Oldest Old, we analyzed genome-wide associations with plasma EC-SOD concentration and associations between EC-SOD concentration and medical history classified by the SOD3 genotype in the Very Old (85–99 years old, n = 505) and Centenarians (over 100 years old, n = 595). The results revealed that SOD3 p.R231G was the most significant variant associated with plasma EC-SOD concentration. Although no significant difference was observed in medical histories between the SOD3 p.R231G variant non-carriers and carriers, higher EC-SOD concentration in plasma of SOD3 p.R231G variant non-carriers was associated with a high odds ratio for chronic kidney disease (OR = 2.70, 95% CI = 1.98–3.72) and low odds ratio for diabetes mellitus (DM) (OR = 0.61, 95% CI = 0.39–0.95). Comparison with 11 plasma biomarkers for age-related disease showed that plasma EC-SOD concentration correlated with adiponectin and estimated glomerular filtration rate with creatinine correction; therefore, we deduced that EC-SOD co-operates with adiponectin and possesses beneficial functions for DM in the Oldest Old.