Endoplasmic reticulum-resident selenoproteins and their roles in glucose and lipid metabolic disorders.

Glucose and lipid metabolic disorders (GLMDs), such as diabetes, dyslipidemia, metabolic syndrome, nonalcoholic fatty liver disease, and obesity, are significant public health issues that negatively impact human health. The endoplasmic reticulum (ER) plays a crucial role at the cellular level for lipid and sterol biosynthesis, intracellular calcium storage, and protein post-translational modifications. Imbalance and dysfunction of the ER can affect glucose and lipid metabolism. As an essential trace element, selenium contributes to various human physiological functions mainly through 25 types of selenoproteins (SELENOs). At least 10 SELENOs, with experimental and/or computational evidence, are predominantly found on the ER membrane or within its lumen. Two iodothyronine deiodinases (DIOs), DIO1 and DIO2, regulate the thyroid hormone deiodination in the thyroid and some external thyroid tissues, influencing glucose and lipid metabolism. Most of the other eight members maintain redox homeostasis in the ER. Especially, SELENOF, SELENOM, and SELENOS are involved in unfolded protein responses; SELENOI catalyzes phosphatidylethanolamine synthesis; SELENOK, SELENON, and SELENOT participate in calcium homeostasis regulation; and the biological significance of thioredoxin reductase 3 in the ER remains unexplored despite its established function in the thioredoxin system. This review examines recent research advances regarding ER SELENOs in GLMDs and aims to provide insights on ER-related pathology through SELENOs regulation.

Intrauterine arsenic exposure induces glucose metabolism disorders in adult offspring by targeting TET2-mediated DNA hydroxymethylation reprogramming of HNF4α in developing livers, an effect alleviated by ascorbic acid.

Exposure to arsenic during gestation has lasting health-related effects on the developing fetus, including an increase in the risk of metabolic disease later in life. Epigenetics is a potential mechanism involved in this process. Ten-eleven translocation 2 (TET2) has been widely considered as a transferase of 5-hydroxymethylcytosine (5hmC). Here, mice were exposed, via drinking water, to arsenic or arsenic combined with ascorbic acid (AA) during gestation. For adult offspring, intrauterine arsenic exposure exhibited disorders of glucose metabolism, which are associated with DNA hydroxymethylation reprogramming of hepatic nuclear factor 4 alpha (HNF4α). Further molecular structure analysis, by SEC-UV-DAD, SEC-ICP-MS, verified that arsenic binds to the cysteine domain of TET2. Mechanistically, arsenic reduces the stability of TET2 by binding to it, resulting in the decrease of 5hmC levels in Hnf4α and subsequently inhibiting its expression. This leads to the disorders of expression of its downstream key glucose metabolism genes. Supplementation with AA blocked the reduction of TET2 and normalized the 5hmC levels of Hnf4α, thus alleviating the glucose metabolism disorders. Our study provides targets and methods for the prevention of offspring glucose metabolism abnormalities caused by intrauterine arsenic exposure.

Circadian rhythm disturbances involved in ozone-induced glucose metabolism disorder in mouse liver.

Ozone (O3) is a key environmental factor for developing diabetes. Nevertheless, the underlying mechanisms remain unclear. This study aimed to investigate alterations of glycometabolism in mice after O3 exposure and the role of circadian rhythms in this process. C57BL/6 male mice were randomly assigned to O3 (0.5 ppm) or filtered air for four weeks (4 h/day). Then, hepatic tissues of mice were collected at 4 h intervals within 24 h after O3 exposure to test. The results showed that hepatic circadian rhythm genes oscillated abnormally, mainly at zeitgeber time (ZT)8 and ZT20 after O3 exposure. Furthermore, detection of glycometabolism (metabolites, enzymes, and genes) revealed that O3 caused change in the daily oscillations of glycometabolism. The serum glucose content decreased at ZT4 and ZT20, while hepatic glucose enhanced at ZT16 and ZT24(0). Both G6pc and Pck1, which are associated with hepatic gluconeogenesis, significantly increased at ZT20. O3 exposure disrupted glycometabolism by increasing gluconeogenesis and decreasing glycolysis in mice liver. Finally, correlation analysis showed that the association between Bmal1 and O3-induced disruption of glycometabolism was the strongest. The findings emphasized the interaction between adverse outcomes of circadian rhythms and glycometabolism following O3 exposure.

KLF7 promotes adipocyte inflammation and glucose metabolism disorder by activating the PKCζ/NF-κB pathway.

In the obesity context, inflammatory cytokines secreted by adipocytes lead to insulin resistance and are key to metabolic syndrome development. In our previous study, we found that the transcription factor KLF7 promoted the expression of p-p65 and IL-6 in adipocytes. However, the specific molecular mechanism remained unclear. In the present study, we found that the expression of KLF7, PKCζ, p-IκB, p-p65, and IL-6 in epididymal white adipose tissue (Epi WAT) in mice fed a high-fat diet (HFD) was significantly increased. In contrast, the expression of PKCζ, p-IκB, p-p65, and IL-6 was significantly decreased in Epi WAT of KLF7 fat conditional knockout mice. In 3T3-L1 adipocytes, KLF7 promoted the expression of IL-6 via the PKCζ/NF-κB pathway. In addition, we performed luciferase reporter and chromatin immunoprecipitation assays, which confirmed that KLF7 upregulated the expression of PKCζ transcripts in HEK-293T cells. Collectively, our results show that KLF7 promotes the expression of IL-6 by upregulating PKCζ expression and activating the NF-κB signaling pathway in adipocytes.

Higher plasma renin activity is associated with increased kidney damage risk in patients with hypertension and glucose metabolic disorders.

The impact of renin on kidney remain unclear among hypertensives with glucose metabolic disorders (GMD). We aimed to evaluate the association between plasma renin activity (PRA) and kidney damage in hypertensive patients with GMD. Overall, 2033 inpatients with hypertension and GMD free of chronic kidney disease (CKD) at baseline were included. CKD was defined using estimated glomerular filtration rate (eGFR) and urine protein. PRA was treated as continuous variable, and also dichotomized as high (≥0.65) or low (< 0.65) groups. The association of PRA with incident CKD was evaluated using multivariable Cox model controlling for antihypertensive medications and baseline aldosterone, and traditional parameters. Subgroup and interaction analyses were performed to evaluate heterogeneity. During a median follow-up of 31 months, 291 participants developed CKD. The incidence was higher in high-renin group than that in low-renin group (54.6 vs 36.6/1000 person-years). Significant association was observed between PRA and incident CKD, and the association was mainly driven by an increased risk for proteinuria. Each standard deviation increment in log-transformed PRA was associated with 16.7% increased risk of proteinuria (hazard ratio = 1.167, P = .03); compared with low-renin group, there was 78.4% increased risk for high-renin group (hazard ratio = 1.784, P = .001). Nonlinear associations were observed between PRA and kidney damage. Higher PRA is associated with greater risk of incident kidney damage, especially for positive proteinuria, in patients with coexistence of hypertension and diabetes, independent of aldosterone. In this patient population with high risk for kidney damage, PRA may serve as an important predictor.

Farnesoid X Receptor Deficiency Induces Hepatic Lipid and Glucose Metabolism Disorder via Regulation of Pyruvate Dehydrogenase Kinase 4.

Farnesoid X receptors (FXR) are bile acid receptors that play roles in lipid, glucose, and energy homeostasis. Synthetic FXR-specific agonists have been developed for treating nonalcoholic fatty liver disease (NAFLD) patients. However, the detailed mechanism remains unclear. To investigate the effects of FXR on NAFLD and the possible mechanism, FXR-null mice were fed either a normal or a high-fat diet. The FXR-null mice developed hepatomegaly, steatosis, accumulation of lipid droplets in liver cells, glucose metabolism disorder, and elevated serum lipid levels. Transcriptomic results showed increased expression of key lipid synthesis and glucose metabolism-related proteins. We focused on pyruvate dehydrogenase kinase 4 (PDK4), a key enzyme involved in the regulation of glucose and fatty acid (FA) metabolism and homeostasis. Subsequently, we confirmed an increase in PDK4 expression in FXR knockout cells. Moreover, inhibition of PDK4 expression alleviated lipid accumulation in hepatocytes caused by FXR deficiency in vivo and in vitro. Our results identify FXR as a nuclear transcription factor that regulates glucose and lipid metabolism balance through PDK4, providing further insights into the mechanism of FXR agonists in the treatment of metabolic diseases.

Biological and Psychological Stress Correlates Are Linked to Glucose Metabolism, Obesity, and Gender Roles in Women.

OBJECTIVES: Psychological stress affects central as well as peripheral metabolism and hormone trafficking via the hypothalamic-pituitary-adrenal axis. Stress thereby plays a decisive role in the etiology and progression of overweight and obesity, leading to several chronic diseases, such as diabetes, and mental health disorders. The interplay of biological and psychometric correlates of stress, anthropometric, immunological, and metabolic parameters and psychosocial factors such as gender roles, however, remains poorly understood. METHODS: In this exploratory study, 43 healthy women were assessed for glucose metabolism by an oral glucose tolerance test and computation of functional parameters for insulin secretion, sensitivity, and resistance. Further, the fatty liver index (FLI) and anthropometric parameters body mass index (BMI), waist-to-hip ratio, body fat, and lean mass were assessed. Psychological stress assessment included the "Brief Symptom Inventory" (BSI), the "Burnout Dimensions Inventory" (BODI), and Perceived Stress Scale (PSS). Biological stress response was evaluated with heart rate variability and cortisol levels. Finally, gender role self-identification was assessed with the "Bem Sex-Role Inventory" (BSRI). Generalized linear models were computed for exploratory association with psychometric outcome. Uncorrected p values are reported. RESULTS: Burnout and PSS scores were associated with insulin secretion, sputum cortisol, thyroid-stimulating hormone, anthropometric measures, and gender role. BSI ratings for psychiatric symptom dimensions were associated with insulin resistance, sex hormones, anthropometric measures, and gender role. Female self-identification was associated with higher BMI as well as body fat and a higher FLI. CONCLUSIONS: Considering the increased risk of unfavorable metabolic, cardiovascular, and also mental health outcome in obese women, a higher BMI in women with predominant female gender self-identification may be relevant for clinical risk assessment. The broad range of interacting biological, psychological, and gender-related parameters calls for an integrative management of both mental and endocrinological health. However, the exploratory nature of the study requires replication in larger samples before definite conclusion can be drawn.

Maternal and fetal metabolomic alterations in maternal lipopolysaccharide exposure-induced male offspring glucose metabolism disorders.

Maternal lipopolysaccharide (LPS) exposure during pregnancy induces metabolic abnormalities in male offspring, but the underlying mechanisms remain unclear. The purpose of this study was to investigate the effects of maternal LPS exposure during pregnancy on metabolic profiling of maternal serum and male fetal liver using Liquid Chromatograph Mass Spectrometer techniques. From day 15 to day 17 of gestation, pregnant mice were administered intraperitoneal LPS (experimental group) (50 µg/kg/d) or saline (control group). On day 18 of gestation, maternal serum and male fetal liver were collected. After LPS exposure, levels of 38 and 75 metabolites, mainly glycerophospholipid and fatty acid metabolites, were altered in maternal serum and male fetal liver, respectively. It was found that in maternal serum and male fetal livers, the glycerophospholipids containing saturated fatty acids (SFAs) and the SFAs were upregulated, while the glycerophospholipids containing polyunsaturated fatty acids (PUFAs) and the PUFAs were downregulated. This concordance between maternal and fetal alterations in glycerophospholipid and fatty acid metabolites may be a metabolomic signature of the early intrauterine period and may provide insight into the mechanisms by which maternal LPS exposure induces disorders of glucose metabolism in male offspring.

The single-point insulin sensitivity estimator (SPISE) index is a strong predictor of abnormal glucose metabolism in overweight/obese children: a long-term follow-up study.

PURPOSE: To investigate the relationship between the single-point insulin sensitivity estimator (SPISE) index, an insulin sensitivity indicator validated in adolescents and adults, and metabolic profile in overweight/obese children, and to evaluate whether basal SPISE is predictive of impaired glucose regulation (IGR) development later in life. METHODS: The SPISE index (= 600 × HDL0.185/Triglycerides0.2 × BMI1.338) was calculated in 909 overweight/obese children undergoing metabolic evaluations at University of Cagliari, Italy, and in 99 normal-weight, age-, sex-comparable children, selected as a reference group, together with other insulin-derived indicators of insulin sensitivity/resistance. 200 overweight/obese children were followed-up for 6.5 [3.5-10] years, data were used for longitudinal retrospective investigations. RESULTS: At baseline, 96/909 (11%) overweight/obese children had IGR; in this subgroup, SPISE was significantly lower than in normo-glycaemic youths (6.3 ± 1.7 vs. 7 ± 1.6, p < 0.001). The SPISE index correlated positively with the insulin sensitivity index (ISI) and the disposition index (DI), negatively with age, blood pressure, HOMA-IR, basal and 120 min blood glucose and insulin (all p values < 0.001). A correlation between SPISE, HOMA-IR and ISI was also reported in normal-weight children. At the 6.5-year follow-up, lower basal SPISE-but not ISI or HOMA-IR-was an independent predictor of IGR development (OR = 3.89(1.65-9.13), p = 0.002; AUROC: 0.82(0.72-0.92), p < 0.001). CONCLUSION: In children, low SPISE index is significantly associated with metabolic abnormalities and predicts the development of IGR in life.

Investigation of possible underlying mechanisms behind water-induced glucose reduction in adults with high copeptin.

Elevated copeptin, a surrogate marker of vasopressin, is linked to low water intake and increased diabetes risk. Water supplementation in habitual low-drinkers with high copeptin significantly lowers both fasting plasma (fp) copeptin and glucose. This study aims at investigating possible underlying mechanisms. Thirty-one healthy adults with high copeptin (> 10.7 pmol·L-1 (men), > 6.1 pmol-1 (women)) and 24-h urine volume of < 1.5L and osmolality of > 600 mOsm·kg-1 were included. The intervention consisted of addition of 1.5 L water daily for 6 weeks. Fp-adrenocorticotropic hormone (ACTH), fp-cortisol, 24-h urine cortisol, fasting and 2 h (post oral glucose) insulin and glucagon were not significantly affected by the water intervention. However, decreased (Δ baseline-6 weeks) fp-copeptin was significantly associated with Δfp-ACTH (r = 0.76, p < 0.001) and Δfp-glucagon (r = 0.39, p = 0.03), respectively. When dividing our participants according to baseline copeptin, median fp-ACTH was reduced from 13.0 (interquartile range 9.2-34.5) to 7.7 (5.3-9.9) pmol L-1, p = 0.007 in the top tertile of copeptin, while no reduction was observed in the other tertiles. The glucose lowering effect from water may partly be attributable to decreased activity in the hypothalamic-pituitary-adrenal axis.ClinicalTrials.gov: NCT03574688.

Clozapine Induced Disturbances in Hepatic Glucose Metabolism: The Potential Role of PGRMC1 Signaling.

Newly emerging evidence has implicated that progesterone receptor component 1 (PGRMC1) plays a novel role not only in the lipid disturbance induced by atypical antipsychotic drugs (AAPD) but also in the deterioration of glucose homoeostasis induced by clozapine (CLZ) treatment. The present study aimed to investigate the role of PGRMC1 signaling on hepatic gluconeogenesis and glycogenesis in male rats following CLZ treatment (20 mg/kg daily for 4 weeks). Recombinant adeno-associated viruses (AAV) were constructed for the knockdown or overexpression of hepatic PGRMC1. Meanwhile, AG205, the specific inhibitor of PGRMC1 was also used for functional validation of PGRMC1. Hepatic protein expressions were measured by western blotting. Meanwhile, plasma glucose, insulin and glucagon, HbA1c and hepatic glycogen were also determined by assay kits. Additionally, concentrations of progesterone (PROG) in plasma, liver and adrenal gland were measured by a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method. Our study demonstrated that CLZ promoted the process of gluconeogenesis and repressed glycogenesis, respectively mediated by PI3K-Akt-FOXO1 and GSK3ß signaling via inhibition of PGRMC1-EGFR/GLP1R in rat liver, along with an increase in fasting blood glucose, HbA1c levels and a decrease in insulin and hepatic glycogen levels. Furthermore, through PGRMC1-EGFR/GLP1R-PI3K-Akt pathway, knockdown or inhibition (by AG205) of PGRMC1 mimics, whereas its overexpression moderately alleviates CLZ-induced glucose disturbances. Potentially, the PGRMC1 target may be regarded as a novel therapeutic strategy for AAPD-induced hepatic glucose metabolism disorder.

Lactobacillus acidophilus NX2-6 Improved High-Fat Diet-Induced Glucose Metabolism Disorder Independent of Promotion of Insulin Secretion in Mice.

High-fat diet (HFD) contributes to metabolic inflammation and glucose metabolism disorder, thereby resulting in the pathogenesis of metabolic syndrome. Accumulating evidence has revealed that some probiotics could improve HFD-induced metabolic inflammation and glucose metabolism disorder. Our previous study has discovered that Lactobacillus acidophilus NX2-6 exhibited in vitro lipid-lowering, antioxidative, and anti-inflammatory activities. This study mainly investigated whether L. acidophilus NX2-6 improved HFD-induced glucose metabolism disorder. The results exhibited that L. acidophilus NX2-6 effectively reduced blood glucose levels and improved glucose tolerance by activating the insulin signaling pathway, promoting glucose uptake, glycolysis, and intestinal gluconeogenesis and suppressing hepatic gluconeogenesis, independent of regulation of glycogen synthesis in the liver and muscle. Enhanced insulin sensitivity was associated with L. acidophilus NX2-6-mediated suppression of inflammatory cascades in the target organs. Meanwhile, L. acidophilus NX2-6 also improved hepatic energy metabolism via the FGF21/AMPKα/PGC-1α/NRF1 pathway. However, L. acidophilus NX2-6 did not affect apoptosis, pyroptosis, inflammation, and endoplasmic reticulum stress in the pancreas of HFD-fed mice. In conclusion, our results indicated that L. acidophilus NX2-6 improved glucose metabolism disorder through enhancing insulin sensitivity, suppressing metabolic inflammation, and promoting energy expenditure.

Roles of microRNAs in carbohydrate and lipid metabolism disorders and their therapeutic potential.

MicroRNAs (miRNAs) are small (∼21 nucleotides), endogenous, non-coding RNA molecules implicated in the post-transcriptional gene regulation performed through target mRNA cleavage or translational inhibition. In recent years, several investigations have demonstrated that miRNAs are involved in regulating both carbohydrate and lipid homeostasis in humans and other organisms. Moreover, it has been observed that the dysregulation of these metabolism-related miRNAs leads to the development of several metabolic disorders, such as type 2 diabetes, obesity, nonalcoholic fatty liver, insulin resistance, and hyperlipidemia. Hence, in this current review, with the aim to impulse the research arena of the micro-transcriptome implications in vital metabolic pathways as well as to highlight the remarkable potential of miRNAs as therapeutic targets for metabolic disorders in humans, we provide an overview of the regulatory roles of metabolism-associated miRNAs in humans and murine models.

Association of Insulin Resistance and ß-cell Function With Bone Turnover Biomarkers in Dysglycemia Patients.

Background: The interrelation between glucose and bone metabolism is complex and has not been fully revealed. This study aimed to investigate the association between insulin resistance, ß-cell function and bone turnover biomarker levels among participants with abnormal glycometabolism. Methods: A total of 5277 subjects were involved through a cross-sectional study (METAL study, http://www.chictr.org.cn, ChiCTR1800017573) in Shanghai, China. Homeostasis model assessment of insulin resistance (HOMA-IR) and ß-cell dysfunction (HOMA-%ß) were applied to elucidate the nexus between ß-C-terminal telopeptide (ß-CTX), intact N-terminal propeptide of type I collagen (P1NP) and osteocalcin (OC). ß-CTX, OC and P1NP were detected by chemiluminescence. Results: HOMA-IR was negatively associated with ß-CTX, P1NP and OC (regression coefficient (ß) -0.044 (-0.053, -0.035), Q4vsQ1; ß -7.340 (-9.130, -5.550), Q4vsQ1 and ß -2.885 (-3.357, -2.412), Q4vsQ1, respectively, all P for trend <0.001). HOMA-%ß was positively associated with ß-CTX, P1NP and OC (ß 0.022 (0.014, 0.031), Q4vsQ1; ß 6.951 (5.300, 8.602), Q4vsQ1 and ß 1.361 (0.921, 1.800), Q4vsQ1, respectively, all P for trend <0.001). Conclusions: Our results support that lower bone turnover biomarker (ß-CTX, P1NP and OC) levels were associated with a combination of higher prevalence of insulin resistance and worse ß-cell function among dysglycemia patients. It is feasible to detect bone turnover in diabetes or hyperglycemia patients to predict the risk of osteoporosis and fracture, relieve patients' pain and reduce the expenses of long-term cure.

Thioredoxin deficiency exacerbates vascular dysfunction during diet-induced obesity in small mesenteric artery in mice.

OBJECTIVE: Thioredoxin (Trx) is a small cellular redox protein with established antioxidant and disulfide reductase properties. We hypothesized that Trx deficiency in mice would cause increased oxidative stress with consequent redox imbalance that would exacerbate obesity-induced vascular dysfunction. METHODS: Non-transgenic (NT, C57BL/6) and dominant-negative Trx (dnTrx-Tg, low levels of redox-active protein) mice were either fed a normal diet (NC) or high fat diet plus sucrose (HFS) diet for 4 months (3-month HFD+ 1-month HFS). Weight gain, glucose tolerance test (GTT), insulin tolerance test (ITT), and other metabolic parameters were performed following NC or HFS diet. Arterial structural remodeling and functional parameters were assessed by myography. RESULTS: Our study found that dnTrx mice with lower levels of active Trx exacerbated myogenic tone, inward arterial remodeling, arterial stiffening, phenylephrine-induced contraction, and endothelial dysfunction of MA. Additionally, FeTMPyP, a peroxynitrite decomposition catalyst, acutely decreased myogenic tone and contraction and normalized endothelial function in MA from dnTrx-Tg mice on HFS via increasing nitric oxide (NO)-mediated relaxation. CONCLUSIONS: Our results indicate that deficiency of active Trx exacerbates MA contractile and relaxing properties during diet-induced obesity demonstrating that loss of redox balance in obesity is a key mechanism of vascular endothelial dysfunction.

Maternal Pre-Pregnancy Obesity Combined With Abnormal Glucose Metabolism Further Increases Adverse Pregnancy Outcomes in Chinese Pregnant Women.

Aims: Our aim was to evaluate the separate and combined effects of maternal pre-pregnancy obesity and gestational abnormal glucose metabolism (GAGM) on adverse perinatal outcomes. Methods: A total of 2,796 Chinese pregnant women with singleton delivery were studied, including 257 women with pre-pregnancy obesity alone, 604 with GAGM alone, 190 with both two conditions, and 1,745 with neither pre-pregnancy obesity nor GAGM as control group. The prevalence and risks of adverse pregnancy outcomes were compared among the four groups. Results: Compared with the normal group, pregnant women with maternal pre-pregnancy obesity alone, GAGM alone, and both two conditions faced significantly increased risks of pregnancy-induced hypertension (PIH) (odds ratio (OR) 4.045, [95% confidence interval (CI) 2.286-7.156]; 1.993 [1.171-3.393]; 8.495 [4.982-14.485]), preeclampsia (2.649 [1.224-5.735]; 2.129 [1.128-4.017]; 4.643 [2.217-9.727]), cesarean delivery (1.589 [1.212-2.083]; 1.328 [1.095-1.611]; 2.627 [1.908-3.617]), preterm delivery (1.899 [1.205-2.993]; 1.358 [0.937-1.968]; 2.301 [1.423-3.720]), macrosomia (2.449 [1.517-3.954]; 1.966 [1.356-2.851]; 4.576 [2.895-7.233]), and total adverse maternal outcomes (1.762 [1.331-2.332]; 1.365 [1.122-1.659]; 3.228 [2.272-4.587]) and neonatal outcomes (1.951 [1.361-2.798]; 1.547 [1.170-2.046]; 3.557 [2.471-5.122]). Most importantly, there were no obvious risk differences in adverse pregnancy outcomes between maternal pre-pregnancy obesity and GAGM group except PIH, but pregnant women with both obesity and GAGM exhibited dramatically higher risks of adverse pregnancy outcomes than those with each condition alone. Conclusions: Maternal pre-pregnancy obesity and GAGM were independently associated with increased risks of adverse pregnancy outcomes. The combination of pre-pregnancy obesity and GAGM further worsens adverse pregnancy outcomes compared with each condition alone.

Branched-chain amino acid metabolism, insulin sensitivity and liver fat response to exercise training in sedentary dysglycaemic and normoglycaemic men.

AIMS/HYPOTHESIS: Obesity and insulin resistance may be associated with elevated plasma concentration of branched-chain amino acids (BCAAs) and impaired BCAA metabolism. However, it is unknown whether the insulin-sensitising effect of long-term exercise can be explained by concomitant change in BCAAs and their metabolism. METHODS: We included 26 sedentary overweight and normal-weight middle-aged men from the MyoGlu clinical trial, with or without dysglycaemia, for 12 weeks of supervised intensive exercise intervention, including two endurance and two resistance sessions weekly. Insulin sensitivity was measured as the glucose infusion rate (GIR) from a hyperinsulinaemic-euglycaemic clamp. In addition, maximum oxygen uptake, upper and lower body strength and adipose tissue depots (using MRI and spectroscopy) were measured, and subcutaneous white adipose tissue (ScWAT) and skeletal muscle (SkM) biopsies were harvested both before and after the 12 week intervention. In the present study we have measured plasma BCAAs and related metabolites using CG-MS/MS and HPLC-MS/MS, and performed global mRNA-sequencing pathway analysis on ScWAT and SkM. RESULTS: In MyoGlu, men with dysglycaemia displayed lower GIR, more fat mass and higher liver fat content than normoglycaemic men at baseline, and 12 weeks of exercise increased GIR, improved body composition and reduced liver fat content similarly for both groups. In our current study we observed higher plasma concentrations of BCAAs (14.4%, p = 0.01) and related metabolites, such as 3-hydroxyisobutyrate (19.4%, p = 0.034) in dysglycaemic vs normoglycaemic men at baseline. Baseline plasma BCAA levels correlated negatively to the change in GIR (ρ = -0.41, p = 0.037) and [Formula: see text] (ρ = -0.47, p = 0.015) after 12 weeks of exercise and positively to amounts of intraperitoneal fat (ρ = 0.40, p = 0.044) and liver fat (ρ = 0.58, p = 0.01). However, circulating BCAAs and related metabolites did not respond to 12 weeks of exercise, with the exception of isoleucine, which increased in normoglycaemic men (10 µmol/l, p = 0.01). Pathway analyses of mRNA-sequencing data implied reduced BCAA catabolism in both SkM and ScWAT in men with dysglycaemia compared with men with normoglycaemia at baseline. Gene expression levels related to BCAA metabolism correlated positively with GIR and markers of mitochondrial content in both SkM and ScWAT, and negatively with fat mass generally, and particularly with intraperitoneal fat mass. mRNA-sequencing pathway analysis also implied increased BCAA metabolism after 12 weeks of exercise in both groups and in both tissues, including enhanced expression of the gene encoding branched-chain α-ketoacid dehydrogenase (BCKDH) and reduced expression of the BCKDH phosphatase in both groups and tissues. Gene expression of SLC25A44, which encodes a mitochondrial BCAA transporter, was increased in SkM in both groups, and gene expression of BCKDK, which encodes BCKDH kinase, was reduced in ScWAT in dysglycaemic men. Mediation analyses indicated a pronounced effect of enhanced SkM (~53%, p = 0.022), and a moderate effect of enhanced ScWAT (~18%, p = 0.018) BCAA metabolism on improved insulin sensitivity after 12 weeks of exercise, based on mRNA sequencing. In comparison, plasma concentration of BCAAs did not mediate any effect in this regard. CONCLUSION/INTERPRETATION: Plasma BCAA concentration was largely unresponsive to long-term exercise and unrelated to exercise-induced insulin sensitivity. On the other hand, the insulin-sensitising effect of long-term exercise in men may be explained by enhanced SkM and, to a lesser degree, also by enhanced ScWAT BCAA catabolism. Graphical abstract.

Glycine Improves Ischemic Stroke Through miR-19a-3p/AMPK/GSK-3ß/HO-1 Pathway.

PURPOSE: To explore the molecular mechanism of glycine in improving ischemic stroke. PATIENTS AND METHODS: The serum samples of patients with ischemic stroke and healthy people were compared. The ischemic stroke model of PC12 cells was established by oxygen-glucose deprivation (OGD). qPCR quantified miR-19a-3p and AMPK mRNA, and protein expression was detected by Western blot. MTT was used to detect cell activity. Flow cytometry was used to detect cells. Glucose metabolism kit was used to detect glucose intake and formation amount of lactic acid. RESULTS: Compared with the control group, OGD group (OGDG) showed lower cell activity and increased cell apoptosis. TNF-α, IL-1ßI, L-6, Caspase 3, Caspase 9 and Bax were up-regulated, and Glut1, HK2, LDHA, PDK1, PKM2 and Bcl2 were down-regulated. At the same time, glucose intake, formation amount of lactic acid and cell apoptosis rate were reduced, and AMPK/GSK-3ß/HO-1 pathway activity was down-regulated. Glycine could counteract the above phenomena in OGDG. miR-19a-3p and AMPK decreased and increased, respectively, during glycine therapy. AMPK was the target gene of miR-19a-3p. Rescue experiments demonstrated that glycine improved cell apoptosis, inflammatory response and glucose metabolism disorder of ischemic stroke through miR-19a-3p/AMPK/GSK-3ß/HO-1 pathway. CONCLUSION: Glycine improves ischemic stroke through miR-19a-3p/AMPK/GSK-3ß/HO-1 pathway.

Zinc Supplementation Alleviates Lipid and Glucose Metabolic Disorders Induced by a High-Fat Diet.

Zinc deficiency is a risk factor for the development of obesity and diabetes. Studies have shown lower serum zinc levels in obese individuals and those with diabetes. We speculate that zinc supplementation can alleviate obesity and diabetes and, to some extent, their complications. To test our hypothesis, we investigated the effects of zinc supplementation on mice with high-fat diet (HFD)-induced hepatic steatosis in vivo and in vitro by adding zinc to the diet of mice and the medium of HepG2 cells. Both results showed that high levels of zinc could alleviate the glucose and lipid metabolic disorders induced by a HFD. High zinc can reduce glucose production, promote glucose absorption, reduce lipid deposition, improve HFD-induced liver injury, and regulate energy metabolism. This study provides novel insight into the treatment of non-alcoholic fatty liver disease and glucose metabolic disorder.