Selenoprotein S: a therapeutic target for diabetes and macroangiopathy?

Hepatokines: unveiling the molecular and cellular mechanisms connecting hepatic tissue to insulin resistance and inflammation

Insulin resistance arising from Non-Alcoholic Fatty Liver Disease (NAFLD) stands as a prevalent global ailment, a manifestation within societies stemming from individuals' suboptimal dietary habits and lifestyles. This form of insulin resistance emerges as a pivotal factor in the development of type 2 diabetes mellitus (T2DM). Emerging evidence underscores the significant role of hepatokines, as hepatic-secreted hormone-like entities, in the genesis of insulin resistance and eventual onset of type 2 diabetes. Hepatokines exert influence over extrahepatic metabolism regulation. Their principal functions encompass impacting adipocytes, pancreatic cells, muscles, and the brain, thereby playing a crucial role in shaping body metabolism through signaling to target tissues. This review explores the most important hepatokines, each with distinct influences. Our review shows that Fetuin-A promotes lipid-induced insulin resistance by acting as an endogenous ligand for Toll-like receptor 4 (TLR-4). FGF21 reduces inflammation in diabetes by blocking the nuclear translocation of nuclear factor-κB (NF-κB) in adipocytes and adipose tissue, while also improving glucose metabolism. ANGPTL6 enhances AMPK and insulin signaling in muscle, and suppresses gluconeogenesis. Follistatin can influence insulin resistance and inflammation by interacting with members of the TGF-β family. Adropin show a positive correlation with phosphoenolpyruvate carboxykinase 1 (PCK1), a key regulator of gluconeogenesis. This article delves into hepatokines' impact on NAFLD, inflammation, and T2DM, with a specific focus on insulin resistance. The aim is to comprehend the influence of these recently identified hormones on disease development and their underlying physiological and pathological mechanisms.

Supplementation of Micro- and Macronutrients-A Role of Nutritional Status in Non-Alcoholic Fatty Liver Disease

Non-alcoholic fatty liver disease (NAFLD) is a condition in which the pathological cumulation of fat with coexisting inflammation and damage of hepatic cells leads to progressive dysfunctions of the liver. Except for the commonly well-known major causes of NAFLD such as obesity, dyslipidemia, insulin resistance, or diabetes, an unbalanced diet and imbalanced nutritional status should also be taken into consideration. In this narrative review, we summarized the current knowledge regarding the micro- and macronutrient status of patients suffering from NAFLD considering various diets and supplementation of chosen supplements. We aimed to summarize the knowledge indicating which nutritional impairments may be associated with the onset and progression of NAFLD at the same time evaluating the potential therapy targets that could facilitate the healing process. Except for the above-mentioned objectives, one of the most important aspects of this review was to highlight the possible strategies for taking care of NAFLD patients taking into account the challenges and opportunities associated with the micronutrient status of the patients. The current research indicates that a supplementation of chosen vitamins (e.g., vitamin A, B complex, C, or D) as well as chosen elements such as zinc may alleviate the symptoms of NAFLD. However, there is still a lack of sufficient data regarding healthy ranges of dosages; thus, further research is of high importance in this matter.

Selenium yeast improve growth, serum biochemical indices, metabolic ability, antioxidant capacity and immunity in black carp Mylopharyngodnpiceus

This experiment was conducted to investigate the impacts of dietary selenium yeast (SeY) on the growth performance, fish body composition, metabolic ability, antioxidant capability, immunity and inflammatory responses in juvenile black carp (Mylopharyngodn piceus). The base diet was supplemented with 0.00, 0.30 and 0.60 g/kg SeY (0.04, 0.59 and 1.15 mg/kg of selenium) to form three isonitrogenous and isoenergetic diets for juvenile black carp with a 60-day. Adequate dietary SeY (0.30 and 0.60 g/kg) could significantly increase the weight gain (WG), special growth rate (SGR) compared to the SeY deficient groups (0.00 g/kg) (P < 0.05). Meanwhile, 0.30 and 0.60 g/kg SeY elevated the mRNA levels of selenoprotein T2 (SEPT2), selenoprotein H (SEPH), selenoprotein S (SEPS) and selenoprotein M (SEPM) in the liver and intestine compared with the SeY deficient groups (P < 0.05). Adequate dietary SeY could promote glucose catabolism and utilization through activating glucose transport (GLUT2), glycolysis (GCK, HK, PFK, PK, PDH), tricarboxylic acid cycle (ICDH and MDH), glycogen synthesis (LG, GCS and GBE) and IRS/PI3K/AKT signal pathway molecules (IRS2b, PI3Kc and AKT1) compared with the SeY deficient groups (P < 0.05). Similarly, adequate dietary SeY could improve lipid transport and triglycerides (TG) synthesis through increasing transcription amounts of CD36, GK, DGAT, ACC and FAS in the fish liver compared with the SeY deficient groups (P < 0.05). In addition, adequate SeY could markedly elevate activities of antioxidant enzymes (T-SOD, CAT, GR, GPX) and contents of T-AOC and GSH, while increased transcription amounts of Nrf2, Cu/Zn-SOD, CAT, and GPX in fish liver and intestine (P < 0.05). However, adequate SeY notably decreased contents of MDA, and the mRNA transcription levels of Keap1 in the intestine compared with the SeY deficient groups (P < 0.05). Adequate SeY markedly increased amounts or levels of the immune factors (ALP, ACP, LZM, C3, C4 and IgM) and the transcription levels of innate immune-related functional genes in the liver and intestine (LZM, C3 and C9) compared to the SeY deficient groups (P < 0.05). Moreover, adequate SeY could notably reduce levels of IL-8, IL-1β, and IFN-γ and elevate TGF-1β levels in fish intestine (P < 0.05). The transcription levels of MAPK13, MAPK14 and NF-κB p65 were notably reduced in fish intestine treated with 0.30 and 0.60 g/kg SeY (P < 0.05). In conclusion, these results suggested that 0.30 and 0.60 g/kg SeY could not only improve growth performance, increase Se, glucose and lipid metabolic abilities, enhance antioxidant capabilities and immune responses, but also alleviate inflammation, thereby supplying useful reference for producing artificial feeds in black carp.

Current views on selenoprotein S in the pathophysiological processes of diabetes-induced atherosclerosis: potential therapeutics and underlying biomarkers

Atherosclerotic cardiovascular disease (ASCVD) consistently ranks as the primary mortality factor among diabetic people. A thorough comprehension of the pathophysiological routes and processes activated by atherosclerosis (AS) caused by diabetes mellitus (DM), together with the recognition of new contributing factors, could lead to the discovery of crucial biomarkers and the development of innovative drugs against atherosclerosis. Selenoprotein S (SELENOS) has been implicated in the pathology and progression of numerous conditions, including diabetes, dyslipidemia, obesity, and insulin resistance (IR)-all recognized contributors to endothelial dysfunction (ED), a precursor event to diabetes-induced AS. Hepatic-specific deletion of SELENOS accelerated the onset and progression of obesity, impaired glucose tolerance and insulin sensitivity, and increased hepatic triglycerides (TG) and diacylglycerol (DAG) accumulation; SELENOS expression in subcutaneous and omental adipose tissue was elevated in obese human subjects, and act as a positive regulator for adipogenesis in 3T3-L1 preadipocytes; knockdown of SELENOS in Min6 β-cells induced β-cell apoptosis and reduced cell proliferation. SELENOS also participates in the early stages of AS, notably by enhancing endothelial function, curbing the expression of adhesion molecules, and lessening leukocyte recruitment-actions that collectively reduce the formation of foam cells. Furthermore, SELENOS forestalls the apoptosis of vascular smooth muscle cells (VSMCs) and macrophages, mitigates vascular calcification, and alleviates inflammation in macrophages and CD4+ T cells. These actions help stifle the creation of unstable plaque characterized by thinner fibrous caps, larger necrotic cores, heightened inflammation, and more extensive vascular calcification-features seen in advanced atherosclerotic lesion development. Additionally, serum SELENOS could function as a potential biomarker, and SELENOS single nucleotide polymorphisms (SNPs) rs4965814, rs28628459, and rs9806366, might be effective gene markers for atherosclerosis-related diseases in diabetes. This review accentuates the pathophysiological processes of atherosclerosis in diabetes and amasses current evidence on SELENOS's potential therapeutic benefits or as predictive biomarkers in the various stages of diabetes-induced atherosclerosis.

The Regulation of Selenoproteins in Diabetes: A New Way to Treat Diabetes

Selenium is an essential micronutrient required for the synthesis and function of selenoproteins, most of which are enzymes involved in maintaining oxidative balance in the body. Diabetes is a group of metabolic disorders characterized by high blood glucose levels over a prolonged period of time. There are three main types of diabetes: type 1, type 2, and gestational diabetes. This review summarizes recent advances in the field of diabetes research with an emphasis on the roles of selenoproteins on metabolic disturbance in diabetes. We also discuss the interaction between selenoproteins and glucose and lipid metabolism to provide new insights into the prevention and treatment of diabetes.

"Alphabet" Selenoproteins: Implications in Pathology

Selenoproteins are a group of proteins containing selenium in the form of selenocysteine (Sec, U) as the 21st amino acid coded in the genetic code. Their synthesis depends on dietary selenium uptake and a common set of cofactors. Selenoproteins accomplish diverse roles in the body and cell processes by acting, for example, as antioxidants, modulators of the immune function, and detoxification agents for heavy metals, other xenobiotics, and key compounds in thyroid hormone metabolism. Although the functions of all this protein family are still unknown, several disorders in their structure, activity, or expression have been described by researchers. They concluded that selenium or cofactors deficiency, on the one hand, or the polymorphism in selenoproteins genes and synthesis, on the other hand, are involved in a large variety of pathological conditions, including type 2 diabetes, cardiovascular, muscular, oncological, hepatic, endocrine, immuno-inflammatory, and neurodegenerative diseases. This review focuses on the specific roles of selenoproteins named after letters of the alphabet in medicine, which are less known than the rest, regarding their implications in the pathological processes of several prevalent diseases and disease prevention.

Characterization and tissue expression of twelve selenoproteins in yellow catfish Pelteobagrus fulvidraco fed diets varying in oxidized fish oil and selenium levels

BACKGROUND

Selenium (Se) functions through selenoproteins and is essential to growth and metabolism of vertebrates. The present study was conducted to identify twelve selenoproteins genes (selenoe, selenof, selenoh, selneoi, selenom, selenok, selneon, selenoo, selenot, selenos, selenou and msrb1) from yellow catfish. Their mRNA expression patterns, as well as their response to dietary oxidized fish oils and Se addition were explored.

METHODS

We use 3'and 5' RACE PCR to clone full-length cDNA sequence of twelve selenoprotein genes from yellow catfish. Their mRNA expression patterns were assessed via quantitative real-time PCR. Yellow catfish were fed diet adequate Se+ fresh fish oil, adequate Se+ oxidized fish oil, high Se+ fresh fish oil and high Se+ oxidized fish oil, respectively, for 10 weeks. Their kidney, heart, brain and testis were used to assess the mRNA expression of twelve selenoprotein.

RESULTS

Twelve selenoprotein genes had similar domains with mammals and the other fish. Their mRNAs were expressed widely in eleven tissues but varied with the tissues. Dietary oxidized fish oils and Se addition influenced their mRNA abundances of twelve selenoproteins in a tissue-dependent manner.

CONCLUSION

Our study demonstrated the characterization and expression of twelve selenoproteins, and elucidated their responses in yellow catfish fed diets varying in oxidized fish oils and Se addition, which increased our knowledge into the biological function and regulatory mechanism of Se and selenoproteins in fish.

Systematic Analysis of Genes Related to Selenium Bioaccumulation in Microalgae: A Review

Se is one of the essential nutrients for human health and animal growth; it participates in various physiological functions, such as antioxidant and immune response and metabolism. Se deficiency is related in the animal industry to poor production performance and the appearance of health problems in humans. Therefore, interest has arisen in producing fortified foods, nutritional supplements, and animal feed products enriched with Se. A sustainable strategy for bio-based products enriched with Se is microalgae. These are characterized by the ability to bioaccumulate inorganic Se and metabolize it into organic Se for product formulations of industrial interest. Although there are some reports on Se bioaccumulation, further exploration is needed to understand the effects of Se bioaccumulation in microalgae. Therefore, this article presents a systematic review of the genes or groups of genes that trigger biological responses associated with the metabolization of Se in microalgae. A total of 54,541 genes related to Se metabolization distributed in 160 different classes were found. Similarly, trends were identified through bibliometric networks on strains of greatest interest, bioproducts, and scientific production.

Selenoprotein S: A versatile disordered protein

Selenoprotein S (selenos) is a small, intrinsically disordered membrane protein that is associated with various cellular functions, such as inflammatory processes, cellular stress response, protein quality control, and signaling pathways. It is primarily known for its contribution to the ER-associated degradation (ERAD) pathway, which governs the extraction of misfolded proteins or misassembled protein complexes from the ER to the cytosol for degradation by the proteasome. However, selenos's other cellular roles in signaling are equally vital, including the control of transcription factors and cytokine levels. Consequently, genetic polymorphisms of selenos are associated with increased risk for diabetes, dyslipidemia, and cardiovascular diseases, while high expression levels correlate with poor prognosis in several cancers. Its inhibitory role in cytokine secretion is also exploited by viruses. Since selenos binds multiple protein complexes, however, its specific contributions to various cellular pathways and diseases have been difficult to establish. Thus, the precise cellular functions of selenos and their interconnectivity have only recently begun to emerge. This review aims to summarize recent insights into the structure, interactome, and cellular roles of selenos.

Emerging roles of selenium on metabolism and type 2 diabetes

Selenium is recognized as an essential element for human health and enters human body mainly via diet. Selenium is a key constituent in selenoproteins, which exert essential biological functions, including antioxidant and anti-inflammatory effects. Several selenoproteins including glutathione peroxidases, selenoprotein P and selenoprotein S are known to play roles in the regulation of type 2 diabetes. Although there is a close association between certain selenoproteins with glucose metabolism or insulin resistance, the relationship between selenium and type 2 diabetes is complex and remains uncertain. Here we review recent advances in the field with an emphasis on roles of selenium on metabolism and type 2 diabetes. Understanding the association between selenium and type 2 diabetes is important for developing clinical practice guidelines, establishing and implementing effective public health policies, and ultimately combating relative health issues.

Investigation of the effects of downregulation of jumping translocation breakpoint (JTB) protein expression in MCF7 cells for potential use as a biomarker in breast cancer

MCF7 is a commonly used luminal type A non-invasive/poor-invasive human breast cancer cell line that does not usually migrate or invade compared with MDA-MB-231 highly metastatic cells, which emphasize an invasive and migratory behavior. Under special conditions, MCF7 cells might acquire invasive features. The aberration in expression and biological functions of the jumping translocation breackpoint (JTB) protein is associated with malignant transformation of cells, based on mitochondrial dysfunction, inhibition of tumor suppressive function of TGF-β, and involvement in cancer cell cycle. To investigate new putative functions of JTB by cellular proteomics, we analyzed the biological processes and pathways that are associated with the JTB protein downregulation. The results demonstrated that MCF7 cell line developed a more "aggressive" phenotype and behavior. Most of the proteins that were overexpressed in this experiment promoted the actin cytoskeleton reorganization that is involved in growth and metastatic dissemination of cancer cells. Some of these proteins are involved in the epithelial-mesenchymal transition (EMT) process (ACTBL2, TUBA4A, MYH14, CSPG5, PKM, UGDH, HSP90AA2, and MIF), in correlation with the energy metabolism reprogramming (PKM, UGDH), stress-response (HSP10, HSP70A1A, HSP90AA2), and immune and inflammatory response (MIF and ERp57-TAPBP). Almost all upregulated proteins in JTB downregulated condition promote viability, motility, proliferation, invasion, survival into a hostile microenvironment, metabolic reprogramming, and escaping of tumor cells from host immune control, leading to a more invasive phenotype for MCF7 cell line. Due to their downregulated condition, four proteins, such as CREBZF, KMT2B, SELENOS and CACNA1I are also involved in maintenance of the invasive phenotype of cancer cells, promoting cell proliferation, migration, invasion and tumorigenesis. Other downregulated proteins, such as MAZ, PLEKHG2, ENO1, TPI2, TOR2A, and CNNM1, may promote suppression of cancer cell growth, invasion, EMT, tumorigenic abilities, interacting with glucose and lipid metabolism, disrupting nuclear envelope stability, or suppressing apoptosis and developing anti-angiogenetic activities. Therefore, the main biological processes and pathways that may increase the tumorigenic potential of the MCF7 cells in JTB downregulated condition are related to the actin cytoskeleton organization, EMT, mitotic cell cycle, glycolysis and fatty acid metabolism, inflammatory response and macrophage activation, chemotaxis and migration, cellular response to stress condition (oxidative stress and hypoxia), transcription control, histone modification and ion transport.

Selenium Status and Its Antioxidant Role in Metabolic Diseases

Selenium (Se), in the form of selenoproteins, is an essential micronutrient that plays an important role in human health and disease. To date, there are at least 25 selenoproteins in humans involved in a wide variety of biological functions, including mammalian development, metabolic progress, inflammation response, chemoprotective properties, and most notably, oxidoreductase functions. In recent years, numerous studies have reported that low Se levels are associated with increased risk, poor outcome, and mortality of metabolic disorders, mainly related to the limited antioxidant defense resulting from Se deficiency. Moreover, the correlation between Se deficiency and Keshan disease has received considerable attention. Therefore, Se supplementation as a therapeutic strategy for preventing the occurrence, delaying the progression, and alleviating the outcomes of some diseases has been widely studied. However, supranutritional levels of serum Se may have adverse effects, including Se poisoning. This review evaluates the correlation between Se status and human health, with particular emphasis on the antioxidant benefits of Se in metabolic disorders, shedding light on clinical treatment.

Gene Networks of Hyperglycemia, Diabetic Complications, and Human Proteins Targeted by SARS-CoV-2: What Is the Molecular Basis for Comorbidity?

People with diabetes are more likely to have severe COVID-19 compared to the general population. Moreover, diabetes and COVID-19 demonstrate a certain parallelism in the mechanisms and organ damage. In this work, we applied bioinformatics analysis of associative molecular networks to identify key molecules and pathophysiological processes that determine SARS-CoV-2-induced disorders in patients with diabetes. Using text-mining-based approaches and ANDSystem as a bioinformatics tool, we reconstructed and matched networks related to hyperglycemia, diabetic complications, insulin resistance, and beta cell dysfunction with networks of SARS-CoV-2-targeted proteins. The latter included SARS-CoV-2 entry receptors (ACE2 and DPP4), SARS-CoV-2 entry associated proteases (TMPRSS2, CTSB, and CTSL), and 332 human intracellular proteins interacting with SARS-CoV-2. A number of genes/proteins targeted by SARS-CoV-2 (ACE2, BRD2, COMT, CTSB, CTSL, DNMT1, DPP4, ERP44, F2RL1, GDF15, GPX1, HDAC2, HMOX1, HYOU1, IDE, LOX, NUTF2, PCNT, PLAT, RAB10, RHOA, SCARB1, and SELENOS) were found in the networks of vascular diabetic complications and insulin resistance. According to the Gene Ontology enrichment analysis, the defined molecules are involved in the response to hypoxia, reactive oxygen species metabolism, immune and inflammatory response, regulation of angiogenesis, platelet degranulation, and other processes. The results expand the understanding of the molecular basis of diabetes and COVID-19 comorbidity.

Selenium and Selenoproteins at the Intersection of Type 2 Diabetes and Thyroid Pathophysiology

Type 2 diabetes (T2D) is considered one of the largest global public-health concerns, affecting approximately more than 400 million individuals worldwide. The pathogenesis of T2D is very complex and, among the modifiable risk factors, selenium (Se) has recently emerged as a determinant of T2D pathogenesis and progression. Selenium is considered an essential element with antioxidant properties, and is incorporated into the selenoproteins involved in the antioxidant response. Furthermore, deiodinases, the enzymes responsible for homeostasis and for controlling the activity of thyroid hormones (THs), contain Se. Given the crucial action of oxidative stress in the onset of insulin resistance (IR) and T2D, and the close connection between THs and glucose metabolism, Se may be involved in these fundamental relationships; it may cover a dual role, both as a protective factor and as a risk factor of T2D, depending on its basal plasma concentration and the individual’s diet intake. In this review we discuss the current evidence (from experimental, observational and randomized clinical studies) on how Se is associated with the occurrence of T2D and its influence on the relationship between thyroid pathophysiology, IR and T2D.

The Role and Mechanisms of Selenium Supplementation on Fatty Liver-Associated Disorder

Non-alcoholic fatty liver disease (NAFLD) is the most frequent chronic liver disease without effective therapy. Selenium, as an essential trace element for humans, is notable for its antioxidant properties. The previous study shows that selenium levels in NAFLD patients are lower than normal ones. Selenium supplementation can effectively alleviate metabolic disorders by relieving anti-oxidative stress and anti-inflammatory regulation. However, the correlation between selenium and NAFLD has not been fully clarified. Herein, we review the current studies on selenium in regulating the different stages of NAFLD and summarize relevant clinical trials to highlight the potential roles of selenium in NAFLD treatment.

The role of selenium in type-2 diabetes mellitus and its metabolic comorbidities

This review addresses the role of the essential trace element, selenium, in type-2 diabetes mellitus (T2DM) and its metabolic co-morbidities, i.e., metabolic syndrome, obesity and non-alcoholic fatty liver disease. We refer to the dietary requirements of selenium and the key physiological roles of selenoproteins. We explore the dysregulated fuel metabolism in T2DM and its co-morbidities, emphasizing the relevance of inflammation and oxidative stress. We describe the epidemiology of observational and experimental studies of selenium in diabetes and related conditions, explaining that the interaction between selenium status and glucose control is not limited to hyperglycemia but extends to hypoglycemia. We propose that the association between high plasma/serum selenium and T2DM/fasting plasma glucose observed in many cross-sectional studies may rely on the upregulation of hepatic selenoprotein-P biosynthesis in conditions of hyperglycemia and insulin resistance. While animal studies have revealed potential molecular mechanisms underlying adverse effects of severe selenium/selenoprotein excess and deficiency in the pathogenesis of insulin resistance and β-cell dysfunction, their translational significance is rather limited. Importantly, dietary selenium supplementation does not appear to be a major causal factor for the development of T2DM in humans though we cannot currently exclude a small contribution of selenium on top of other risk factors, in particular if it is ingested at high (supranutritional) doses. Elevated selenium biomarkers that are often measured in T2DM patients are more likely to be a consequence, rather than a cause, of diabetes.

Selenoprotein S attenuates high glucose and/or ox-LDL-induced endothelium injury by regulating Akt/mTOR signaling and autophagy

Glucolipid metabolism disorder in diabetes mellitus (DM) causes human endothelial injury and autophagy dysfunction is an important cause of endothelial dysfunction (ED). Selenoprotein S (SelS) could protect endothelium from oxidative stress, inflammatory responses, and apoptosis. This study assessed the effect of SelS on autophagy in glucolipid metabolic disorders and protection of the resulted vascular endothelial injury. The results showed that high glucose (HG), high oxidized low-density lipoprotein (HL), and HG combined with HL (HGL) could reduce viability of human aortic endothelial cells (HAECs), induce HAECs injury and increase SelS expression in a time-dependent manner. HG, HL, and HGL also initially induced autophagy but later reduced it in HAECs, while activity of the Akt/mTOR signaling was inhibited, especially in HGL culture of HAECs. SelS overexpression reduced the endothelial injury and autophagy and activated the Akt/mTOR signaling in HG, HL and HGL-cultured HAECs, compared to the control. Conversely, knockdown of SelS expression had the opposite effects on HAECs. In conclusion, SelS demonstrated a protective effect on endothelial injury induced by high glucose and/or ox-LDL and the underlying molecular events might be related to its regulation of HAECs autophagy by activating the Akt/mTOR signaling. SelS could be a potential intervention target in prevention and treatment of diabetic vascular complications.

Single-cell RNA-sequencing atlas of bovine caudal intervertebral discs: Discovery of heterogeneous cell populations with distinct roles in homeostasis

Back and neck pain are significant healthcare burdens that are commonly associated with pathologies of the intervertebral disc (IVD). The poor understanding of the cellular heterogeneity within the IVD makes it difficult to develop regenerative IVD therapies. To address this gap, we developed an atlas of bovine (Bos taurus) caudal IVDs using single-cell RNA-sequencing (scRNA-seq). Unsupervised clustering resolved 15 unique clusters, which we grouped into the following annotated partitions: nucleus pulposus (NP), outer annulus fibrosus (oAF), inner AF (iAF), notochord, muscle, endothelial, and immune cells. Analyzing the pooled gene expression profiles of the NP, oAF, and iAF partitions allowed us to identify novel markers for NP (CP, S100B, H2AC18, SNORC, CRELD2, PDIA4, DNAJC3, CHCHD7, and RCN2), oAF (IGFBP6, CTSK, LGALS1, and CCN3), and iAF (MGP, COMP, SPP1, GSN, SOD2, DCN, FN1, TIMP3, WDR73, and GAL) cells. Network analysis on subpopulations of NP and oAF cells determined that clusters NP1, NP2, NP4, and oAF1 displayed gene expression profiles consistent with cell survival, suggesting these clusters may uniquely support viability under the physiological stresses of the IVD. Clusters NP3, NP5, oAF2, and oAF3 expressed various extracellular matrix (ECM)-associated genes, suggesting their role in maintaining IVD structure. Lastly, transcriptional entropy and pseudotime analyses found that clusters NP3 and NP1 had the most stem-like gene expression signatures of the NP partition, implying these clusters may contain IVD progenitor cells. Overall, results highlight cell type diversity within the IVD, and these novel cell phenotypes may enhance our understanding of IVD development, homeostasis, degeneration, and regeneration.

Selenomethionine activates selenoprotein S, suppresses Fas/FasL and the mitochondrial pathway, and reduces Escherichia coli-induced apoptosis of bovine mammary epithelial cells

Escherichia coli is a major environmental pathogen causing bovine mastitis, characterized by cell death and mammary tissue damage. Apoptosis, a form of cell death, has an important role in the pathogenesis of mastitis. Selenium, an essential trace element, protects against mastitis by acting through several biochemical pathways, potentially including prevention of apoptosis. Our objective was to investigate whether selenomethionine (SeMet) attenuated E. coli-induced apoptosis in bovine mammary epithelial cells (bMEC). These cells were cultured in vitro and treated with 0, 5, 10, 20, and 40 μM SeMet for 12 h, with or without E. coli (multiplicity of infection of 5) for 8 h. Treatment with SeMet/Z-IE(OMe)TD(OMe)-FMK (ZIK)/Z-LE(OMe)HD(OMe)-FMK (ZLK, specific inhibitors of caspase-8 and -9, respectively) significantly counteracted effects of E. coli on bMEC. Specifically, SeMet upregulated selenoprotein S (SeS) and increased mitochondrial membrane potential and the ratio of Bcl-2 and Bax. Furthermore, it decreased protein expressions of Fas, FasL, FADD, cleaved caspase-8, cytochrome c, cleaved caspase-9, and cleaved caspase-3, namely, decreasing protein expression of the Fas/FasL and mitochondrial pathways. Furthermore, it downregulated total apoptosis indexes in E. coli-infected bMEC. Although ZIK and ZLK (specific inhibitors of caspases 8 and 9, respectively) significantly inhibited Fas/FasL and the mitochondrial apoptotic pathway and apoptosis indexes, respectively, substantial apoptosis still occurred. In conclusion, SeMet attenuated E. coli-induced apoptosis in bMEC by activating SeS, associated with Fas/FasL and mitochondrial pathways.

Factors affecting diabetic patient's long-term quality of life after simultaneous pancreas-kidney transplantation: a single-center analysis

PURPOSE

Pancreas transplantation (PT) is one of the few ways to restore euglycemia within diabetic patients; however, the high morbidity caused by surgical complications and the need for immunosuppressive therapy has raised controversy about PT improving the health-related quality-of-life (HRQoL). The aim of this study is to assess the long-term (≥ 5 years after PT) HRQoL and to identify the factors affecting it.

METHODS

A single-center, cross-sectional study of 49 sequential PT was performed. All patients conducted a telephone interview to fulfill the modification of Medical Outcome Health Survey Short Form questionnaire (SF-36v2) and were compared to similar post-PT studies from the literature.

RESULTS

Patients with a history of replacement renal therapy (RRT) or neuropathy undergoing a PT were associated to a worse bodily pain (P = 0.03) and physical function (P = 0.04), respectively, whereas those with retinopathy showed an improved Role Emotional (P = 0.04). Multivariate analysis revealed the presence of RRT as the only independent prognostic factor for a worse bodily pain [relative risk = 3.9; 95% confidence interval (1.1-14.6)], (P = 0.04). Furthermore, nearly all PT recipients (91.8%) claimed an overall better health than prior to PT.

CONCLUSION

Our study confirms that PT recipients' HRQoL improves after PT, showing similar HRQoL scores across different populations and suggests that patients in predialysis could benefit from an improved HRQoL if transplanted on the early stages of the disease.

Combination of Astragalus membranaceous and Angelica sinensis Ameliorates Vascular Endothelial Cell Dysfunction by Inhibiting Oxidative Stress

Vascular endothelial dysfunction is an essential and early sign of diabetic macroangiopathy, a primary complication of diabetes mellitus. Astragalus membranaceous-Angelica sinensis is a classic medical combination applied in China to treat diabetes mellitus. The aim of this study was to investigate the effect of the granule form of the extract produced from the dried root of Astragalus membranaceous (AM) combination with the granule form of the extract produced from the dried Angelica sinensis (AS) on diabetic macroangiopathy and its underlying mechanism. Herein, rats were treated by AM-AS at a ratio of 3 : 2 via intragastric administration. High glucose-induced human umbilical vein vascular endothelial cells (HUVECs) were then treated with drug-containing serum collected from the rats. In high glucose-treated HUVECs, AM-AS combination increased cell viability (P < 0.05), decreased the percentage of apoptotic cells (P < 0.05) and the expression of the proapoptosis protein caspase 3 (P < 0.05), reduced the proportion of cells in the G0/G1 phase (P < 0.05), decreased reactive oxygen species level (P < 0.05), enhanced cell migration and invasion (P < 0.05), and reduced the level of 8-iso-prostaglandin F2alpha. These results indicate that AM-AS combination at the ratio of 3 : 2 ameliorated HUVEC dysfunction by regulating apoptosis, cell migration, and invasion, which might be mediated by their regulatory effect on reactive oxygen species production. The current study provides a theoretical basis for the treatment of diabetic macroangiopathy using AM-AS.

Selenoprotein T: An Essential Oxidoreductase Serving as a Guardian of Endoplasmic Reticulum Homeostasis

Significance: Selenoproteins incorporate the essential nutrient selenium into their polypeptide chain. Seven members of this family reside in the endoplasmic reticulum (ER), the exact function of most of which is poorly understood. Especially, how ER-resident selenoproteins control the ER redox and ionic environment is largely unknown. Since alteration of ER function is observed in many diseases, the elucidation of the role of selenoproteins could enhance our understanding of the mechanisms involved in ER homeostasis. Recent Advances: Among selenoproteins, selenoprotein T (SELENOT) is remarkable as the most evolutionarily conserved and the only ER-resident selenoprotein whose gene knockout in mouse is lethal. Recent data indicate that SELENOT contributes to ER homeostasis: reduced expression of SELENOT in transgenic cell and animal models promotes accumulation of reactive oxygen and nitrogen species, depletion of calcium stores, activation of the unfolded protein response and impaired hormone secretion. Critical Issues: SELENOT is anchored to the ER membrane and associated with the oligosaccharyltransferase complex, suggesting that it regulates the early steps of N-glycosylation. Furthermore, it exerts a selenosulfide oxidoreductase activity carried by its thioredoxin-like domain. However, the physiological role of the redox activity of SELENOT is not fully understood. Likewise, the nature of its redox partners needs to be further characterized. Future Directions: Given the impact of ER stress in pathologies such as neurodegenerative, cardiovascular, metabolic and immune diseases, understanding the role of SELENOT and developing derived therapeutic tools such as selenopeptides to improve ER proteostasis and prevent ER stress could contribute to a better management of these diseases.

Selenocysteine insertion sequence binding protein 2 (Sbp2) in the sex-specific regulation of selenoprotein gene expression in mouse pancreatic islets

Selenoproteins are a group of selenocysteine-containing proteins with major roles in cellular antioxidant defense and thyroid hormone metabolism. Selenoprotein expression is determined by hierarchical mechanisms that result in tissue-specific levels. Current data inadequately explain the abundance of various selenoproteins under normal and pathological conditions, including in pancreatic β-cells. Selenocysteine insertion sequence binding protein 2 (SBP2) is a critical protein in selenoprotein translation that also plays an essential role in stabilizing selenoprotein transcripts by antagonizing nonsense-mediated decay (NMD). Importantly, dysfunctional SBP2 is associated with endocrine disorders in humans. Here we describe the impact of induced Sbp2 deficiency in pancreatic β-cells on selenoprotein transcript profiles in the pancreatic islets of C57BL/6J mice. Sex differences were noted in control mice, in which female islets showed 5 selenoproteins decreased and one increased versus male islets. Induced Sbp2 deficiency in pancreatic β-cells altered expression of only 3 selenoprotein transcripts in male islets, whereas 14 transcripts were reduced in female islets. In all cases, decreased transcription was observed in genes known to be regulated by NMD. The differential impact of Sbp2 deletion on selenoprotein transcription between sexes suggests sex-specific hierarchical mechanisms of selenoprotein expression that may influence islet biology and consequentially metabolic disease risk.

Leishmanial selenoproteins and the host immune system: towards new therapeutic strategies?

Optimum levels of selenoproteins are essential for starting and managing the host immune responses against pathogens. According to the expression of selenoproteins in Leishmania parasites, and since high levels of selenoproteins lead to adverse effects on immune cells and their functions, Leishmania parasites might then express selenoproteins such as selenomethionine in their structure and/or secretions able to challenge the host immune system. Finally, this adaptation may lead to evasion of the parasite from the host immune system. The expression of selenoproteins in Leishmania parasites might then induce the development of infection. We therefore suggest these molecules as new therapeutic candidates for the treatment of leishmaniasis.

High glucose and TGF-β1 reduce expression of endoplasmic reticulum-resident selenoprotein S and selenoprotein N in human mesangial cells

There are seven endoplasmic reticulum (ER)-resident selenoproteins in human body and they can regulate the inflammation, oxidative stress, and ER stress. We established transforming growth factor-β1 (TGF-β1) or high glucose (HG) induced human mesangial cells (HMCs) fibronectin expression model in vitro. Next, the expression changes of seven ER-resident selenoproteins were detected under HG conditions and we found selenoprotein S (SELENOS), selenoprotein N (SELENON) were significantly down-regulated but selenoprotein M was significantly up-regulated in transcription level. Furthermore, we found that TGF-β1 and HG down-regulated the expression of SELENOS and SELENON in a time- and dose-dependent manner, respectively. Finally, SELENOS was knocked down by siRNA and we found that knocking down SELENOS decreased TGF-β1 induced fibronectin expression. Our research indicates the potential value of ER-resident selenoproteins on renal fibrosis.

Selenium and iodine in diabetes mellitus with a focus on the interplay and speciation of the elements

Diabetes mellitus is a chronic metabolic disease caused by insulin deficiency (type I) or dysfunction (type II). Diabetes is a threatening public health concern. It is considered as one of the priority non-communicable diseases, due to its high and increasing incidence, the associated healthcare costs, and threatening medical complications. Two trace elements selenium (Se) and iodine (I) were intensively discussed in the context of diabetic pathology and, possibly, etiology. It seems there is a multilayer involvement of these essential nutrients in glucose tolerance, energy metabolism, insulin signaling and resistance, which are mainly related to the antioxidant selenoenzymes and the thyroid hormones. Other factors might be related to (auto)immunity, protection against endoplasmic reticulum stress, and leptin signaling. The aim of the current review is to evaluate the current understanding of the role of selenium and iodine in diabetes with a focus on the biochemical interplay between the elements, their possible role as biomarkers, and their chemical speciation. Possible impacts from novel analytical techniques related to trace element speciation and isotopic analysis are outlined.

Systems Biology of Selenium and Complex Disease

Selenium is an essential trace element for maintenance of overall health, whose deficiency and dyshomeostasis have been linked to a variety of diseases and disorders. The majority of previous researches focused on characterization of genes encoding selenoproteins or proteins involved in selenium metabolism as well as their functions. Many studies in humans also investigated the relationship between selenium and complex diseases, but their results have been inconsistent. In recent years, systems biology and "-omics" approaches have been widely used to study complex and global variations of selenium metabolism and function in physiological and different pathological conditions. The present paper reviews recent progress in large-scale and systematic analyses of the relationship between selenium status or selenoproteins and several complex diseases, mainly including population-based cohort studies and meta-analyses, genetic association studies, and some other omics-based studies. Advances in ionomics and its application in studying the interaction between selenium and other trace elements in human health and diseases are also discussed.

Serum selenoprotein P, but not selenium, predicts future hyperglycemia in a general Japanese population

We aimed to test the hypothesis that selenoprotein P (SELENOP), a hepatokine involved in the development of both insulin resistance and impaired insulin production in mice, is related to future onset of hyperglycemia in humans. 76 healthy non-pregnant human subjects without diabetes underwent oral glucose tolerance test (OGTT) at baseline and 4-years follow-up. Nine subjects developed either impaired glucose tolerance or type 2 diabetes at follow-up. At baseline, SELENOP concentrations correlated negatively with insulinogenic index, but not with homeostasis model assessment-estimated insulin resistance (HOMA-IR). Multivariate analysis showed that baseline SELENOP predicted fasting plasma glucose at follow-up independently of the other parameters. The receiver operating characteristic (ROC) curve analysis showed that baseline concentrations of serum SELENOP, but not of selenium, were a reliable test to predict future onset of glucose intolerance. In conclusion, elevation of circulating SELENOP, but not of circulating selenium, was positively and independently associated with future onset of glucose intolerance in a general Japanese population.