GLUT4 mRNA Research Articles

Effects of Adiponectin on Glucose Metabolism in the Hepatopancreas of Grass Carp (Ctenopharyngodon idella)

Adiponectin plays critical roles in the regulation of energy metabolism in mammals. However, its roles in fish remain to be evaluated. In this study, we examined the tissue distribution characteristics of two adiponectin genes, namely, adipoqa and adipoqb, at transcriptional level, and detected the changes of their mRNA expressions during oral glucose tolerance test (OGTT). Furthermore, we prepared recombinant proteins of grass carp adiponectin A and adiponectin B and studied their roles in the regulation of glucose metabolism in the hepatopancreas of grass carp in vivo. The results showed that adipoqa mRNA was mainly expressed in the heart of grass carp, followed by red muscle, white muscle, and adipose tissue, while adipoqb mRNA was highly expressed in adipose tissue, red muscle, and white muscle. The mRNA levels of adipoqa and adipoqb in the white muscle and heart were significantly decreased at 1 h post OGTT, and their expressions in the heart were also suppressed at 3 h, whereas the transcriptional levels of adipoqa and adipoqb in the red muscle were elevated significantly at 12 h after glucose load. Intraperitoneal injection of adiponectin A or adiponectin B reduced basal serum glucose levels of grass carp and caused an increase of glycogen content in the hepatopancreas. Adiponectin A upregulated the expression of enzyme genes related to glycolysis (gk and pk) and glycogen synthesis (gys) in the hepatopancreas, and adiponectin B promoted the expression of pk and gys, as well as g6pase in the glycogenetic pathway. Besides, adiponectin A and adiponectin B have opposite regulatory effects on glut2 mRNA expression. These results suggested that adiponectin A and adiponectin B promoted glycolysis, gluconeogenesis, and glycogen synthesis, increased glycogen content of hepatopancreas, and reduced basal blood glucose level, and they may have an antagonistic regulatory mechanism in regulating glucose uptake.

An Exploratory Study of the Role of Dietary Proteins in the Regulation of Intestinal Glucose Absorption.

Several studies have demonstrated that high protein diets improve glucose homeostasis. Nevertheless, the mechanisms underlying this effect remain elusive. This exploratory study aims to screen and compare the acute effects of dietary proteins from different sources on intestinal glucose absorption. Six dietary proteins from various sources were thus selected and digested thanks to the INFOGEST static gastrointestinal digestion protocol. The digested proteins were able to decrease intestinal glucose absorption in vitro and ex vivo. Moreover, acute ingestion of casein and fish gelatin led to improved glucose tolerance in Wistar rats without significant effect on insulin secretion. In parallel, GLUT2 mRNA expression in enterocytes was decreased following short-term incubation with some of the digested proteins. These results strengthen the evidence that digested protein-derived peptides and amino acids are key regulators of glucose homeostasis and highlight their role in intestinal glucose absorption.

Molecular cloning and characterization of GLUT2 from pompano (Trachinotus ovatus), and its gene expression in response to exogenous enzymes supplementation in high carbohydrate diet

Glucose transport across membranes mediated by glucose transporter protein (GLUTs) is a momentous process in tissue glucose metabolism and blood glucose regulation. In this experiment, the glucose transporter 2 of pompano, Trachinotus ovatus (ToGLUT2) was cloned and identified. A 56-day breeding experiment was performed to study the effects of exogenous enzymes supplementation in high carbohydrate diets on the mRNA expression of ToGLUT2. The pompano (38.50 ± 0.50 g) used in this experiment were fed five diets (46% protein, 5.8% lipid), one of which was the control group (non-enzyme) and the remaining four groups were supplemented with four kinds of exogenous enzymes (amylase, glucoamylase, pullulanase and complex enzymes). The experimental results showed that the cDNA full length of 2280 bp, a 3′-UTR of 610 bp, a 5′-UTR of 32 bp, an open reading frame of 1638 bp, and a polypeptide of 546 amino acids are characteristic of ToGLUT2 (GenBank accession No: MK649830). Analysis of the phylogenetic tree revealed that the highest similarity was found between ToGLUT2 and Dicentrarchus labrax GLUT2. The results of qRT-PCR showed that ToGLUT2 gene was ubiquitously observed among tissues tested and was expressed at the highest level in the liver, closely followed by the intestine and brain. However, the poorest expression of ToGLUT2 was detected in the muscle, kidney and heart; the findings indicated that the glucokinase (GK) and 6-phosphofructo kinase − 1 (PFK-1) activities were significantly highest in the high carbohydrate group (H) (P < 0.05), followed by the amylase group (A) (P < 0.05), and finally the complex enzymes group (C) (P < 0.05); to respects of digestive enzymes, the intestinal amylase (AMS) in the amylase group (A) was not significantly difference compared to the high carbohydrate group (H) (P > 0.05), and was significantly lower in all other groups (P < 0.05). The trypsin (TRP) in the complex enzymes group (C) was significantly highest compared to the high carbohydrate group (H), followed by the amylase group (A), and finally in the glucoamylase group (G). The lipase (LPS) was significantly highest in the amylase group (A) compared to the high carbohydrate group (H) (P < 0.05), while it was significantly lower in the glucoamylase (G) and pullulanse groups (P) (P < 0.05), with no significant difference in the complex enzyme group (C) (P > 0.05). Hence, the activity of digestive enzymes can be improved by the addition of carbohydrase in feed; in terms of serum biochemical parameters, there was no significant difference in glucose concentration for all treatment groups (P > 0.05). Insulin concentration was not significant difference in the pullulanase group (P) compared to the high carbohydrate group (H) (P > 0.05), while it was significantly lower in all other groups (P < 0.05). Liver glycogen in the amylase group (A), glucoamylase group (G) and pullulanase group (P) was significantly higher compared to the high carbohydrate group (H) (P < 0.05), with no significant difference in the complex enzyme group (C) (P > 0.05). Muscle glycogen was not significantly different in the glucoamylase group (G) compared to the high carbohydrate group (H) (P > 0.05), while it was significantly lower in all other groups (P < 0.05); GLUT2 mRNA expression from liver and muscle was significantly up-regulated in the glucoamylase group (G) compared to the high carbohydrate group (H) (P < 0.05), while it was significantly lowest in the pullulanase group (P) and the complex enzyme group (C) (P < 0.05). In conclusion, GLUT2 from pompano showed the typical structure of glucose transporter protein family with high sequence homology with other species, which could improve the utilization of enhanced carbohydrates; the addition of carbohydrase to the high carbohydrate diet had different degrees of impacts on the growth performance, digestive enzymes, glucose metabolism and GLUT2 gene expression of pompano trevally, especially the glucoamylase group, which could significantly improve the utilization of carbohydrate.

The Bioactive Flavonoid Taxifolin Inhibits Differentiation and the Production of the Inflammatory Cytokine Interleukin-6 in Cultured Human Adipocytes

Background: Taxifolin, a bioactive flavonoid that possesses potent antioxidant activity, has been reported to show multiple pharmacological properties, including protective effects against obesity-related diabetic nephropathy and diabetic cardiomyopathy. However, knowledge regarding the effects of taxifolin on adipocytes, which are closely associated with obesity and diabetes, is insufficient. Objective: This study aimed to explore the direct effects of taxifolin on differentiation and inflammation adipocytes by culturing human preadepocytes (HPAds). Methods: HPAds were cultured for 16 days in a differentiation medium with or without taxifolin to examine its effect on differentiation. On day 16, levels of lipid and differentiation-related gene expression (PPARγ, C/EBPα, adiponectin, CD36, and GLUT4 mRNAs) in adipocytes were measured using the Oil Red O assay and the real-time polymerase chain reaction assay, respectively. Adiponectin levels in the medium were measured using an enzyme-linked immunosorbent assay (ELISA). The taxifolin effect on inflammation was assessed using mature adipocytes differentiated for 15 days. After incubating mature adipocytes in a differentiation medium containing tumor necrosis factor-α (TNF-α) or TNF-α + taxifolin for three hours, the level of interleukin-6 (IL-6), an inflammatory cytokine in the medium, was measured using ELISA. Results: Exposure of taxifolin to adipocytes during differentiation decreased the levels of lipid in adipocytes and adiponectin in the medium. It also decreased the expression levels of C/EBPα, adiponectin, CD36, and GLUT4 mRNAs, but not PPARγ mRNA. Taxifolin inhibited the increase in IL-6 levels in the medium induced by TNF-α in mature adipocytes. Conclusion: These results suggest that taxifolin has anti-differentiation and anti-inflammatory effects on adipocytes. Additionally, taxifolin is expected to have the potential as a therapeutic drug for obesity and metabolic syndrome.

Melatonin alleviates insulin resistance through the PI3K/AKT signaling pathway in ovary granulosa cells of polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is a common endocrine gynecological disorder. Insulin resistance (IR) is a major cause of PCOS. Melatonin, a critical endogenous hormone, has beneficial effects on the female reproductive system. This study aims to investigate the molecular effect of melatonin on IR in human ovarian granulosa cells (GCs). Hormone levels of the subjects were determined through clinical examination. The expression levels of insulin receptor substrate (IRS)-1 and glucose transporter (GLUT4) in GCs from PCOS patients and a human granulosa cell line (SVOG) were examined using qRT-PCR and western blot. The IR cell model was established by inducing SVOG cells with palmitic acid (PA). IR was detected in GCs of PCOS patients and SVOG by measuring glucose content and glucose uptake. Cell viability and apoptosis levels were detected by CCK-8 assay and flow cytometry. PI3K/Akt pathway expression in SVOG was assessed by western blot. PCOS patients had higher levels of luteinizing hormone (LH), testosterone, and LH/follicle-stimulating hormone. PA decreased cell viability, promoted apoptosis, and reduced glucose uptake in SVOG cells. IRS-1 and GLUT4 mRNA and protein expression was downregulated, and glucose uptake capacity was reduced in PCOS GCs and SVOG cells. Melatonin significantly upregulated IRS-1 and GLUT4 expression, downregulated p-IRS-1 (Ser307), and improved glucose uptake in PCOS patients' GCs and SVOG cells. PA decreased PI3K and Akt phosphorylation, whereas melatonin increased p-PI3K and p-Akt levels. Melatonin can reduce IR in GCs and PA-induced SVOG cells via the PI3K/Akt signaling pathway, providing more evidence for treating polycystic ovary syndrome.

New Intracellular Peptide Derived from Hemoglobin Alpha Chain Induces Glucose Uptake and Reduces Blood Glycemia.

Intracellular peptides were shown to derive from proteasomal degradation of proteins from mammalian and yeast cells, being suggested to play distinctive roles both inside and outside these cells. Here, the role of intracellular peptides previously identified from skeletal muscle and adipose tissues of C57BL6/N wild type (WT) and neurolysin knockout mice were investigated. In differentiated C2C12 mouse skeletal muscle cells, some of these intracellular peptides like insulin activated the expression of several genes related to muscle contraction and gluconeogenesis. One of these peptides, LASVSTVLTSKYR (Ric4; 600 µg/kg), administrated either intraperitoneally or orally in WT mice, decreased glycemia. Neither insulin (10 nM) nor Ric4 (100 µM) induced glucose uptake in adipose tissue explants obtained from conditional knockout mice depleted of insulin receptor. Ric4 (100 µM) similarly to insulin (100 nM) induced Glut4 translocation to the plasma membrane of C2C12 differentiated cells, and increased GLUT4 mRNA levels in epididymal adipose tissue of WT mice. Ric4 (100 µM) increased both Erk and Akt phosphorylation in C2C12, as well as in epididymal adipose tissue from WT mice; Erk, but not Akt phosphorylation was activated by Ric4 in tibial skeletal muscle from WT mice. Ric4 is rapidly degraded in vitro by WT liver and kidney crude extracts, such a response that is largely reduced by structural modifications such as N-terminal acetylation, C-terminal amidation, and substitution of Leu8 for DLeu8 (Ac-LASVSTV[DLeu]TSKYR-NH2; Ric4-16). Ric4-16, among several Ric4 derivatives, efficiently induced glucose uptake in differentiated C2C12 cells. Among six Ric4-derivatives evaluated in vivo, Ac-LASVSTVLTSKYR-NH2 (Ric4-2; 600 µg/kg) and Ac-LASVSTV[DLeu]TSKYR (Ric4-15; 600 µg/kg) administrated orally efficiently reduced glycemia in a glucose tolerance test in WT mice. The potential clinical application of Ric4 and Ric4-derivatives deserves further attention.

Effect of high salinity acclimation on glucose homeostasis in Mozambique tilapia (Oreochromis mossambicus).

During salinity stress, osmoregulatory processes in euryhaline fish need to modify for their survival, and glucose is the preferred mode of extra energy during such conditions. These organisms must have a proper mechanism to maintain glucose homeostasis during such modified osmoregulatory process across different body fluids. Hence, we studied high salinity effect on regulation of glucose homeostasis in Mozambique tilapia. The fish were induced to 15‰ salinity for 21 days. Glucose, glycogen, ion concentrations, Na+-K+-ATPase, pyruvate kinase, γ-amylase activities and GLUT mRNA expressions were investigated in liver, intestine, gill and white muscle tissues. At the end of experiment, Na+ ion concentrations, glucose content and activity of Na+-K+-ATPase especially in the gill and intestine were increased, while decrease in liver and gill glycogen content was seen. Lower concentration of glycogen decrease was observed in the intestine and white muscle of the treated group. High pyruvate kinase activity was noticed in liver and gill tissues that correlates with high Na+-K+-ATPase activity. Elevated γ-amylase activity was observed in the liver and intestine suggesting breakdown of glycogen; however, gill and white muscle did not show any increased activity. Increase in GLUT1 and GLUT4 mRNA expressions was observed especially in the gill and intestine, while increase in GLUT2 mRNA expressions was observed in the liver. Upregulations of GLUTs suggest higher influx of glucose into the cell for catabolism to provide energy and further to drive the enhanced osmoregulatory process. These findings suggest glucose homeostasis being regulated in Mozambique tilapia during salinity acclimation.

Glucose transporter 4 mRNA expression in subcutaneous adipose tissue of women with PCOS remains unchanged despite metformin withdrawal: is there a cellular metabolic treatment legacy effect?

Metformin induces GLUT-4 mRNA expression in insulin target tissues in PCOS. It is unclear how long this impact is sustained after withdrawal of metformin. We aimed to compare the effect of metformin withdrawal on GLUT-4 mRNA expression in subcutaneous adipose tissue after prior short (ST, 1 year, N = 11) and long term (LT, at least 3 years, N = 13) treatment in obese PCOS women. At baseline and 6 months after withdrawal, biopsy of subcutaneous adipose tissue followed by quantitative PCR analysis was performed to determine GLUT-4 mRNA expression. We found no time/effect differences in GLUT-4 mRNA expression in ST (2-dCt at baseline 0.42 (0.16-0.48) vs 2-dCt after 6 months 0.31 (0.22-0.56), p = 0.594) and no time/effect difference in LT group (2-dCt at baseline 0.24 (0.14-0.39) vs 2-dCt after 6 months 0.25 (0.20-0.38), p = 0.382). There was also no difference in GLUT-4 mRNA expression between both groups at baseline and after 6 months. In summary, 6 months after metformin withdrawal, GLUT-4 mRNA expression in subcutaneous adipose tissue remained stable, regardless of the prior treatment duration.

Momordica charantia nanoparticles promote mitochondria biogenesis in the pancreas of diabetic-induced rats: gene expression study

BackgroundMitochondria dysfunction is one of the clinical features of diabetes mellitus (DM), which is a hallmark of insulin resistance (IR). This study investigates the therapeutic effect of Momordica charantia nanoparticles on mitochondria biogenesis in diabetic-induced rats. Forty-two adult wistar rats (average weight of 189 ± 10.32) were grouped as follows: STZ (65 mg/kg), control group, STZ + silver nitrate (10 mg/kg), STZ + M. charantia silver nanoparticles (50 mg/kg), STZ + metformin (100 mg/kg), and STZ + M. charantia aqueous extract (100 mg/kg). DM was induced intraperitoneal using freshly prepared solution of STZ (65 mg/kg), and rats with fasting blood sugar (FBS) above 250 mg/dl after 72 h of induction were considered diabetic. Treatment started after the third day of induction and lasted for 11 days. Effect of M. charantia nanoparticles on glucose level and pancreatic expression of genes involved in mitochondria biogenesis (PGC-1α, AMPK, GSK-3β, PPARϒ), inflammation (IL-1B, TNFα) and glucose sensitivity (PI3K, AKT, PTEN Insulin and Glut2) were quantified using reverse-transcriptase polymerase chain reaction (RT-PCR).ResultsThe results showed that M. charantia nanoparticles promote mitochondria biogenesis, glucose sensitivity and reverse inflammation in the pancreas of diabetes rat model through upregulation of PGC-1α, AMPK, PPARϒ, AKT, Insulin and Glut2 mRNA expression and downregulation of GSK-3β, PI3K, IL-1B and TNFα mRNA expression in the pancreas of diabetic rats.ConclusionThis study thus concludes that M. charantia nanoparticles may provide effective therapeutics against mitochondria dysfunction in the pancreas of diabetic model.

The unexplored role of sedentary time and physical activity in glucose and lipid metabolism-related placental mRNAs in pregnant women who are obese: the DALI lifestyle randomised controlled trial.

We aimed to explore: (i) the association of sedentary time (ST) and physical activity (PA) during pregnancy with the placental expression of genes related to glucose and lipid metabolism in pregnant women who are obese; (ii) maternal metabolic factors mediating changes in these placental transcripts; and (iii) cord blood markers related to the mRNAs mediating neonatal adiposity. Multicentre randomised controlled trial. Hospitals in nine European countries. A cohort of 112 pregnant women with placental tissue. Both ST and moderate-to-vigorous PA (MVPA) levels were measured objectively using accelerometry at three time periods during pregnancy. Placental mRNAs (FATP2, FATP3, FABP4, GLUT1 and PPAR-γ) were measured with NanoString technology. Maternal and fetal metabolic markers and neonatal adiposity were assessed. Longer periods of ST, especially in early to middle pregnancy, was associated with lower placental FATP2 and FATP3 expression (P < 0.05), whereas MVPA at baseline was inversely associated with GLUT1 mRNA (P = 0.02). Although placental FATP2 and FATP3 expression were regulated by the insulin-glucose axis (P < 0.05), no maternal metabolic marker mediated the association of ST/MVPA with placental mRNAs (P > 0.05). Additionally, placental FATP2 expression was inversely associated with cord blood triglycerides and free fatty acids (FFAs; P < 0.01). No cord blood marker mediated neonatal adiposity except for cord blood leptin, which mediated the effects of PPAR-γ on neonatal sum of skinfolds (P < 0.05). In early to middle pregnancy, ST is associated with the expression of placental genes linked to lipid transport. PA is hardly related to transporter mRNAs. Strategies aimed at reducing sedentary behaviour during pregnancy could modulate placental gene expression, which may help to prevent unfavourable fetal and maternal pregnancy outcomes. Reducing sedentary behaviour in pregnancy might modulate placental expression of genes related to lipid metabolism in women who are obese.

Metabolic Consequences of Neuronal HIF1α-Deficiency in Mediobasal Hypothalamus in Mice.

ObjectiveThis study aims to investigate whether hypoxia-inducible factor 1α (HIF1α) in the neurons of the mediobasal hypothalamus is involved in the regulation of body weight, glucose, and lipid metabolism in mice and to explore the underlying molecular mechanisms.MethodsHIF1α flox/flox mice were used. The adeno-associated virus that contained either cre, GFP and syn, or GFP and syn (controls) was injected into the mediobasal hypothalamus to selectively knock out HIF1α in the neurons of the mediobasal hypothalamus. The body weight and food intake were weighed daily. The levels of blood glucose, insulin, total cholesterol (TC), triglyceride (TG), free fatty acid (FFA), high-density lipoprotein (HDL), and low-density lipoprotein (LDL)were tested. Intraperitoneal glucose tolerance test (IPGTT) was performed. The insulin-stimulated Akt phosphorylation in the liver, epididymal fat, and skeletal muscle were examined. Also, the mRNA expression levels of HIF1α, proopiomelanocortin (POMC), neuropeptide Y (NPY), and glucose transporter protein 4 (Glut4) in the hypothalamus were checked.ResultsAfter selectively knocking out HIF1α in the neurons of the mediobasal hypothalamus (HIF1αKOMBH), the body weights and food intake of mice increased significantly compared with the control mice (p < 0.001 at 4 weeks). Compared with that of the control group, the insulin level of HIF1αKOMBH mice was 3.5 times higher (p < 0.01). The results of the IPGTT showed that the blood glucose level of the HIF1αKOMBH group at 20–120 min was significantly higher than that of the control group (p < 0.05). The serum TC, FFA, HDL, and LDL content of the HIF1αKOMBH group was significantly higher than those of the control group (p < 0.05). Western blot results showed that compared with those in the control group, insulin-induced AKT phosphorylation levels in liver, epididymal fat, and skeletal muscle in the HIF1αKOMBH group were not as significantly elevated as in the control group. Reverse transcription-polymerase chain reaction (RT-PCR) results in the whole hypothalamus showed a significant decrease in Glut4 mRNA expression. And the mRNA expression levels of HIF1α, POMC, and NPY of the HIF1αKOMBH group decreased significantly in ventral hypothalamus.ConclusionsThe hypothalamic neuronal HIF1α plays an important role in the regulation of body weight balance in mice under normoxic condition. In the absence of hypothalamic neuronal HIF1α, the mice gained weight with increased appetite, accompanied with abnormal glucose and lipid metabolism. POMC and Glut4 may be responsible for this effect of HIF1α.

Bone Marrow Mesenchymal Stem Cell (BMSC)-Derived Exosomes Increase Colon Cancer Cell Apoptosis and Inhibit Proliferation and Migration

This study aims to investigate whether bone marrow mesenchymal stem cell (BMSC) exosomes (BMSC-exos) affects the progression of colon cancer. Ultracentrifugation was used to extract and collect BMSC-exos which were assessed under electron microscope and by flow cytometry. The BMSCs were divided into two groups: control group treated with α-MEM basal medium and experimental group with exosomes (10 μg/ml). Exos were extracted from BMSCs and co-cultured with colon cancer cells, followed by analysis of cell viability by CCK-8 assay and GLUT3 mRNA and protein expression by RT-qPCR and Western blot. The electron microscope analysis indicated that the primary BMSCs showed a long spindle shape with a negative expression of antigen CD34 and positive antigen CD90. Importantly, exos inhibited the viability of colon cancer cells HCT116 and decreased the expression of GLUT3, suggesting that exos might increase the colon cancer cell apoptosis. In conclusion, BMSC-exos inhibit cell progression in colon cancer and might be served as a promising biomarker.

Impact of maternal late gestation undernutrition on surfactant maturation, pulmonary blood flow and oxygen delivery measured by magnetic resonance imaging in the sheep fetus.

Restriction of fetal substrate supply has an adverse effect on surfactant maturation in the lung and thus affects the transition from in utero placental oxygenation to pulmonary ventilation ex utero. The effects on surfactant maturation are mediated by alteration in mechanisms regulating surfactant protein and phospholipid synthesis. This study aimed to determine the effects of late gestation maternal undernutrition (LGUN) and LGUN plus fetal glucose infusion (LGUN+G) compared to Control on surfactant maturation and lung development, and the relationship with pulmonary blood flow and oxygen delivery ( ) measured by magnetic resonance imaging (MRI) with molecules that regulate lung development. LGUN from 115 to 140days' gestation significantly decreased fetal body weight, which was normalized by glucose infusion. LGUN and LGUN+G resulted in decreased fetal plasma glucose concentration, with no change in fetal arterial compared to control. There was no effect of LGUN and LGUN+G on the mRNA expression of surfactant proteins (SFTP) and genes regulating surfactant maturation in the fetal lung. However, blood flow in the main pulmonary artery was significantly increased in LGUN, despite no change in blood flow in the left or right pulmonary artery and to the fetal lung. There was a negative relationship between left pulmonary artery flow and to the left lung with SFTP-B and GLUT1 mRNA expression, while their relationship with VEGFR2 was positive. These results suggest that increased pulmonary blood flow measured by MRI may have an adverse effect on surfactant maturation during fetal lung development. KEY POINTS: Maternal undernutrition during gestation alters fetal lung development by impacting surfactant maturation. However, the direction of change remains controversial. We examined the effects of maternal late gestation maternal undernutrition (LGUN) on maternal and fetal outcomes, signalling pathways involved in fetal lung development, pulmonary haemodynamics and oxygen delivery in sheep using a combination of molecular and magnetic resonance imaging (MRI) techniques. LGUN decreased fetal plasma glucose concentration without affecting arterial . Surfactant maturation was not affected; however, main pulmonary artery blood flow was significantly increased in the LGUN fetuses. This is the first study to explore the relationship between in utero MRI measures of pulmonary haemodynamics and lung development. Across all treatment groups, left pulmonary artery blood flow and oxygen delivery were negatively correlated with surfactant protein B mRNA and protein expression in late gestation.

A microenvironment of high lactate and low pH created by the blastocyst promotes endometrial receptivity and implantation

Research questionIs the blastocyst's idiosyncratic metabolic production of lactate, and creation of a specialized microenvironment at the implatation site, an important mediator of maternal–fetal signalling to promote endometrial receptivity and implantation? DesignHormonally primed ECC-1 and Ishikawa cells were used to assess functional changes to the endometrial epithelium after exposure to lactic acid (LA), LA with neutralized pH (nLA) or acidic pH (pHL). Tight junction integrity (transepithelial resistance [TER]), cellular proliferation or changes to gene expression by RT-PCR were analysed. The effect of LA on Endometrial stromal cells decidualization and migratory capacity, and HUVEC endothelial tube formation and angiogenesis, were also assessed. ResultsTreatment of ECC-1 cells with 2.5 mM (P = 0.0037), 5 mM (P = 0.0044), 7.5 mM and 10 mM (P = 0.003) (P = 0.0021) LA significantly decreased the rate of cellular proliferation while TER was decreased with exposure to 2.5 mM LA (P = 0.024), 5 mM LA (P = 0.021) and 7.5 mM LA (P = 0.033). Exposure to nLA or pHL had no effect on proliferation or TER. Upregulation of GLUT4 (P = 0.002), GPR81 (P = 0.048), VEGF, SNAI1 (both P < 0.001) and RELA (P = 0.023) mRNA expression was observed after exposure of Ishikawa cells to combined LA plus pHL. Lactic acid increased the migratory capacity of decidualized stromal cells (P = 0.047) without changing the extent of decidualization. HUVEC tube formation was significantly increased by 5 mM LA exposure (P = 0.009). ConclusionsThe identification of LA as an important mediator in the maternal–fetal dialogue underpinning implantation is supported. Further examination of the role of LA within the infertile or compromised endometrium could improve natural and assisted pregnancy success and needs further investigation.

Molecular identification of glucose transporter 4: The responsiveness to starvation, glucose, insulin and glucagon on glucose transporter 4 in common carp (Cyprinus carpio L.).

Glucose transporter 4 (GLUT4) is comprehensively investigated in mammals, while the comparative research of GLUT4 in common carp is deficient. To investigate the function of GLUT4, carp glut4 was first isolated. The open reading frame of carp glut4 was 1518 bp in length, encoding 505 amino acids. A high-sequence homology was identified in carp and teleost, and the phylogenetic tree displayed that the carp GLUT4 was clustered with the teleost. A high level of glut4 mRNA was analysed in fat, red muscle and white muscle. After fasting treatment, glut4 mRNA expression was increased significantly in muscle. In the oral glucose tolerance test experiment, glut4 mRNA was also significantly elevated in muscle, gut and fat. Furthermore, intraperitoneal injection of insulin resulted in the upregulation of glut4 gene expression significantly in white muscle, gut and fat. On the contrary, the glut4 mRNA level in the white muscle, gut and fat was markedly downregulated after glucagon injection. These results suggest that GLUT4 might play important roles in food intake and could be regulated by nutrient condition, insulin and glucagon in common carp. Our study is the first to report on GLUT4 in common carp. These data provide a basis for further study on fish GLUT4.

M6 A transferase KIAA1429-stabilized LINC00958 accelerates gastric cancer aerobic glycolysis through targeting GLUT1.

Emerging evidence has demonstrated that N6 -methyladenosine (m6 A) and long noncoding RNAs (lncRNAs) are both crucial regulators in gastric cancer (GC) tumorigenesis. However, the interaction of m6 A and lncRNAs in GC progression are still unclear. Here, our team discovered that lncRNA LINC00958 expression up-regulated in GC tissue and cells. Clinically, high-expression of LINC00958 was clinically correlated to lower survival of GC patients. Functionally, in vitro assays demonstrated that LINC00958 promoted the GC cells' aerobic glycolysis. Mechanistically, methylated RNA immunoprecipitation sequencing (MeRIP-Seq) found that there were m6 A-modificated sites in LINC00958, and moreover m6 A methyltransferase KIAA1429 catalyzed the m6 A modification on LINC00958 loci. Moreover, LINC00958 interacted with GLUT1 mRNA via the m6 A-dependent manner to enhance GLUT1 mRNA transcript stability, thereby positively regulating the aerobic glycolysis of GC. In conclusion, our findings reveal the function and mechanism of KIAA1429-induced LINC00958 in GC, delineating novel understanding of m6 A-lncRNA in cancer biology.

Agriophyllum Oligosaccharides Ameliorate Diabetic Insulin Resistance Through INS-R/IRS/Glut4-Mediated Insulin Pathway in db/db Mice and MIN6 Cells.

We have previously reported that Agriophyllum oligosaccharides (AOS) significantly enhance glycemic control by increasing the activation of insulin receptor (INS-R), insulin receptor substrate-2 (IRS-2), phosphatidylinositol 3 kinase (PI3K), protein kinase B (AKT), peroxisome proliferator-activated receptor (PPAR)-γ, and glucose transporter 4 (Glut4) proteins in hepatic tissues. However, the effect of glucose control by AOS on the regulation of pancreatic tissues in db/db mice and MIN6 cells remains to be determined. An oral dose of AOS (380 or 750 mg/kg) was administered to type-2 diabetic db/db mice for 8 weeks to determine whether AOS regulates glucose by the INS-R/IRS/Glut4-mediated insulin pathway. Meanwhile, the effects of AOS on glucose uptake and its related signaling pathway in MIN6 cells were also investigated. The results showed that the random blood glucose (RBG) level in the AOS-treated group was lower than that in the control group. AOS reduced the levels of glycated hemoglobin (HbA1c) and free fatty acid (FFA) and significantly improved the pathological changes in the pancreatic tissues in db/db mice. Moreover, immunohistochemical analysis revealed that the expression of INS-R, IRS-1, IRS-2, and Glut4 was increased in the AOS-treated group than in the model group. Further, in vitro experiments using MIN6 cells showed that AOS regulated INS-R, IRS-1, IRS-2, and Glut4 protein and mRNA levels and attenuated insulin resistance and cell apoptosis. The results of both in vitro and in vivo experiments were comparable. Ultra-performance liquid chromatography coupled with time-of-flight mass spectrometric analysis of AOS with precolumn derivatization with 3-amino-9-ethylcarbazole (AEC) tentatively identified five types of sugars: glucose, lactose, rutinose, glucuronic acid, and maltotriose. Our present study clearly showed that AOS is efficacious in preventing hyperglycemia, possibly by increasing insulin sensitivity and improving IR by regulating the INS-R/IRS/Glut4 insulin signal pathway. Therefore, AOS may be considered as a potential drug for diabetes treatment.

Chronic and Intermittent Hyperglycemia Modulates Expression of Key Molecules of PI3K/AKT Pathway in Differentiating Human Visceral Adipocytes.

Background: Due to its prominence in the regulation of metabolism and inflammation, adipose tissue is a major target to investigate alterations in insulin action. This hormone activates PI3K/AKT pathway which is essential for glucose homeostasis, cell differentiation, and proliferation in insulin-sensitive tissues, like adipose tissue. The aim of this work was to evaluate the impact of chronic and intermittent high glucose on the expression of biomolecules of insulin signaling pathway during the differentiation and maturation of human visceral preadipocytes. Methods: Human visceral preadipocytes (HPA-V) cells were treated with high glucose (30 mM)during the proliferation and/or differentiation and/or maturation stage. The level of mRNA (by Real-Time PCR) and protein (by Elisa tests) expression of IRS1, PI3K, PTEN, AKT2, and GLUT4 was examined after each culture stage. Furthermore, we investigated whether miR-29a-3p, miR-143-3p, miR-152-3p, miR-186-5p, miR-370-3p, and miR-374b-5p may affect the expression of biomolecules of the insulin signaling pathway. Results: Both chronic and intermittent hyperglycemia affects insulin signaling in visceral pre/adipocytes by upregulation of analyzed PI3K/AKT pathway molecules. Both mRNA and protein expression level is more dependent on stage-specific events than the length of the period of high glucose exposure. What is more, miRs expression changes seem to be involved in PI3K/AKT expression regulation in response to hyperglycemic stimulation.

Prenylflavonoids from fruit of Macaranga tanarius promote glucose uptake via AMPK activation in L6 myotubes.

Skeletal muscle is a major tissue of glucose consumption and plays an important role in glucose homeostasis. Prenylflavonoids, a component of Macaranga tanarius fruits, have been reported to have antioxidant, antibacterial, and anticancer effects. However, the effects of these compounds on skeletal muscle glucose metabolism are unclear. Here, we isolated five prenylflavonoids from M. tanarius fruits, and investigated the mechanism of action of these compounds on skeletal muscle cells using L6 myotubes. We found that isonymphaeol B and 3'-geranyl naringenin increased glucose uptake in a dose-dependent manner. Furthermore, both isonymphaeol B and 3'-geranyl naringenin increased AMPK phosphorylation but did not affect PI3K-Akt phosphorylation. Isonymphaeol B and 3'-geranyl naringenin also increased Glut1 mRNA expression and plasma membrane GLUT1 protein levels. These results suggest that isonymphaeol B and 3'-geranyl naringenin have beneficial effects on glucose metabolism through AMPK and GLUT1 pathway. Isonymphaeol B and 3'-geranyl naringenin may be potential lead candidates for antidiabetic drug development.

Modifications of physical and functional integrity of the blood-brain barrier in an inducible mouse model of neurodegeneration

The inducible p25 overexpression mouse model recapitulate many hallmark features of Alzheimer's disase including progressive neuronal loss, elevated Aβ, tau pathology, cognitive dysfunction, and impaired synaptic plasticity. We chose p25 mice to evaluate the physical and functional integrity of the blood-brain barrier (BBB) in a context of Tau pathology (pTau) and severe neurodegeneration, at an early (3 weeks ON) and a late (6 weeks ON) stage of the pathology. Using in situ brain perfusion and confocal imaging, we found that the brain vascular surface area and the physical integrity of the BBB were unaltered in p25 mice. However, there was a significant 14% decrease in cerebrovascular volume in 6 weeks ON mice, possibly explained by a significant 27% increase of collagen IV in the basement membrane of brain capillaries. The function of the BBB transporters GLUT1 and LAT1 was evaluated by measuring brain uptake of d-glucose and phenylalanine, respectively. In 6 weeks ON p25 mice, d-glucose brain uptake was significantly reduced by about 17% compared with WT, without any change in the levels of GLUT1 protein or mRNA in brain capillaries. The brain uptake of phenylalanine was not significantly reduced in p25 mice compared with WT. Lack of BBB integrity, impaired BBB d-glucose transport have been observed in several mouse models of AD. In contrast, reduced cerebrovascular volume and an increased basement membrane thickness may be more specifically associated with pTau in mouse models of neurodegeneration.