Reciprocal control of pyruvate dehydrogenase kinase and phosphatase by inositol phosphoglycans. Dynamic state set by "push-pull" system

Placenta and maternal endothelium during preeclampsia: Disruption of the glycocalyx explains increased inositol phosphoglycans and angiogenic factors in maternal blood

The etiology of the pregnancy syndrome preeclampsia is still unclear, while most hypotheses center on the placenta as the major contributor of the syndrome. Especially changes of the placental metabolism, including the use of glucose to produce energy, are important features. As an example, inositol phosphoglycan P-type molecules, second messengers involved in the glucose metabolism of all cells, can be retrieved from maternal urine of preeclamptic women, even before the onset of clinical symptoms. Alterations in the placental metabolism may subsequently lead to negative effects on the plasma membrane of the placental syncytiotrophoblast. This in turn may have deleterious effects on the glycocalyx of this layer and a disruption of this layer in all types of preeclampsia. The interruption of the glycocalyx in preeclampsia may result in changes of inositol phosphoglycan P-type signaling pathways and the release of these molecules as well as the release of soluble receptors such as sFlt-1 and sEndoglin. The release of placental factors later affects the maternal endothelium and disrupts the endothelial glycocalyx as well. This in turn may pave the way for edema, endothelial dysfunction, coagulation, all typical symptoms of preeclampsia.

Inflammation primes the kidney for recovery by activating AZIN1 A-to-I editing

The progression of kidney disease varies among individuals, but a general methodology to quantify disease timelines is lacking. Particularly challenging is the task of determining the potential for recovery from acute kidney injury following various insults. Here, we report that quantitation of post-transcriptional adenosine-to-inosine (A-to-I) RNA editing offers a distinct genome-wide signature, enabling the delineation of disease trajectories in the kidney. A well-defined murine model of endotoxemia permitted the identification of the origin and extent of A-to-I editing, along with temporally discrete signatures of double-stranded RNA stress and Adenosine Deaminase isoform switching. We found that A-to-I editing of Antizyme Inhibitor 1 (AZIN1), a positive regulator of polyamine biosynthesis, serves as a particularly useful temporal landmark during endotoxemia. Our data indicate that AZIN1 A-to-I editing, triggered by preceding inflammation, primes the kidney and activates endogenous recovery mechanisms. By comparing genetically modified human cell lines and mice locked in either A-to-I edited or uneditable states, we uncovered that AZIN1 A-to-I editing not only enhances polyamine biosynthesis but also engages glycolysis and nicotinamide biosynthesis to drive the recovery phenotype. Our findings implicate that quantifying AZIN1 A-to-I editing could potentially identify individuals who have transitioned to an endogenous recovery phase. This phase would reflect their past inflammation and indicate their potential for future recovery.

Differential Gene Expression and Biological Analyses of Primary Hepatocytes Following D-Chiro-Inositol Supplement

Dietary supplements have improved the prevention of insulin resistance and metabolic diseases, which became a research hotspot in food science and nutrition. Obesity and insulin resistance, caused by a high-fat diet, eventually result in severe metabolic diseases, can be prevented with the dietary supplement D-chiro-inositol (DCI). In this work, we isolated mice primary hepatocytes with palmitic acid stimulation and DCI was applied to compare and contrast its effects of in primary hepatocyte biology. Before and after intervention with DCI, we used RNA-Seq technology to establish a primary hepatocyte transcriptome gene profile. We found that both PA and DCI cause a wide variation in gene expression. Particularly, we found that DCI plays critical role in this model by acting on glycolysis and gluconeogenesis. Overall, we generated extensive transcripts from primary hepatocytes and uncovered new functions and gene targets for DCI.

A review of the role of inositols in conditions of insulin dysregulation and in uncomplicated and pathological pregnancy

Inositols, a group of 6-carbon polyols, are highly bioactive molecules derived from diet and endogenous synthesis. Inositols and their derivatives are involved in glucose and lipid metabolism and participate in insulin-signaling, with perturbations in inositol processing being associated with conditions involving insulin resistance, dysglycemia and dyslipidemia such as polycystic ovary syndrome and diabetes. Pregnancy is similarly characterized by substantial and complex changes in glycemic and lipidomic regulation as part of maternal adaptation and is also associated with physiological alterations in inositol processing. Disruptions in maternal adaptation are postulated to have a critical pathophysiological role in pregnancy complications such as gestational diabetes and pre-eclampsia. Inositol supplementation has shown promise as an intervention for the alleviation of symptoms in conditions of insulin resistance and for gestational diabetes prevention. However, the mechanisms behind these affects are not fully understood. In this review, we explore the role of inositols in conditions of insulin dysregulation and in pregnancy, and identify priority areas for research. We particularly examine the role and function of inositols within the maternal-placental-fetal axis in both uncomplicated and pathological pregnancies. We also discuss how inositols may mediate maternal-placental-fetal cross-talk, and regulate fetal growth and development, and suggest that inositols play a vital role in promoting healthy pregnancy.

d- chiro-Inositol Ameliorates High Fat Diet-Induced Hepatic Steatosis and Insulin Resistance via PKCε-PI3K/AKT Pathway

d- chiro-Inositol (DCI) is a biologically active component found in tartary buckwheat, which can reduce hyperglycemia and ameliorate insulin resistance. However, the mechanism underlying the antidiabetic effects of DCI remains largely unclear. This study investigated the effects and underlying molecular mechanisms of DCI on hepatic gluconeogenesis in mice fed a high fat diet and saturated palmitic acid-treated hepatocytes. DCI attenuated free fatty acid uptake by the liver via lipid trafficking inhibition, reduced diacylglycerol deposition, and hepatic PKCε translocation. Thus, DCI could improve insulin sensitivity by suppressing hepatic gluconeogenesis. Subsequent analyses revealed that DCI decreased hepatic glucose output and the expression levels of PEPCK and G6 Pase in insulin resistant mice through PKCε-IRS/PI3K/AKT signaling pathway. Likewise, such effects of DCI were confirmed in HepG2 cells with palmitate-induced insulin resistance. These findings indicate a novel pathway by which DCI prevents hepatic gluconeogenesis, reduces lipid deposition, and ameliorates insulin resistance via regulation of PKCε-PI3K/AKT axis.

Loss of SETD2 Induces a Metabolic Switch in Renal Cell Carcinoma Cell Lines toward Enhanced Oxidative Phosphorylation

SETD2, a histone H3 lysine trimethyltransferase, is frequently inactivated and associated with recurrence of clear cell renal cell carcinoma (ccRCC). However, the impact of SETD2 loss on metabolic alterations in ccRCC is still unclear. In this study, SETD2 null isogenic 38E/38F clones derived from 786-O cells were generated by zinc finger nucleases, and subsequent metabolic, genomic, and cellular phenotypic changes were analyzed by targeted metabolomics, RNA sequencing, and biological methods, respectively. Our results showed that compared with parental 786-O cells, 38E/38F cells had elevated levels of MTT/Alamar blue levels, ATP, glycolytic/mitochondrial respiratory capacity, citrate synthase (CS) activity, and TCA metabolites such as aspartate, malate, succinate, fumarate, and α-ketoglutarate. The 38E/38F cells also utilized alternative sources beyond pyruvate to generate acetyl-CoA for the TCA cycle. Moreover, 38E/38F cells showed disturbed gene networks mainly related to mitochondrial metabolism and the oxidation of fatty acids and glucose, which was associated with increased PGC1α, mitochondrial mass, and cellular size/complexity. Our results indicate that SETD2 deficiency induces a metabolic switch toward enhanced oxidative phosphorylation in ccRCC, which can be related to PGC1α-mediated metabolic networks. Therefore, this current study lays the foundation for the further development of a global metabolic analysis of cancer cells in individual patients, which ultimately will have significant potential for the discovery of novel therapeutics and precision medicine in SETD2-inactivated ccRCC.

Synthesis of C-Glycoinositols from C-Glycosylcrotylstannanes

A strategy for the synthesis of C-pseudodisaccharides that centers on the reaction of a C-linked crotyltin and a substituted pent-4-enal and a ring-closing metathesis-alkene dihydroxylation sequence on the derived crotylation products is illustrated in the preparation of analogues of the insulin modulatory inositol galactosamine-β-(1 → 4)-3-O-methyl-d- chiro-inositol (β-INS-2). The modularity of this approach and versatility of the pivotal crotylation products make this a potentially general methodology for diverse libraries of C-glycoinositols.

Historical evolution of ideas on eclampsia/preeclampsia: A proposed optimistic view of preeclampsia

Eclampsia (together with epilepsy) being the first disease ever written down since the beginning of writings in mankind 5000 years ago, we will make a brief presentation of the different major steps in comprehension of Pre-eclampsia. 1) 1840. Rayer, description of proteinuria in eclampsia, 2) 1897 Vaquez, discovery of gestational hypertension in eclamptic women, 3) In the 1970's, description of the "double" trophoblastic invasion existing only in humans (Brosens & Pijnenborg,), 4) between the 1970's and the 1990's, description of preeclampsia being a couple disease. The "paternity problem" (and therefore irruption of immunology), 5) at the end of the 1980's, a major step forward: Preeclampsia being a global endothelial cell disease (glomeruloendotheliosis, hepatic or cerebral endotheliosis, HELLP, eclampsia), inflammation (J.Roberts.C Redman, R Taylor), 6) End of the 1990's: Consensus for a distinction between early onset preeclampsia EOP and late onset LOP (34 weeks gestation), EOP being rather a problem of implantation of the trophoblast (and the placenta), LOP being rather a pre-existing maternal problem (obesity, diabetes, coagulopathies etc…). LOP is predominant everywhere on this planet, but enormously predominant in developed countries: 90% of cases. This feature is very different in countries where women have their first child very young (88% of world births), where the fatal EOP (early onset) occurs in more than 30% of cases. 7) What could be the common factor which could explain the maternal global endotheliosis in EOP and LOP? Discussion about the inositol phospho glycans P type.

The Prevention of Gestational Diabetes Mellitus With Antenatal Oral Inositol Supplementation: A Randomized Controlled Trial

OBJECTIVE

This study investigated if inositol in a combination of myo-inositol and D-chiro-inositol would prevent gestational diabetes mellitus (GDM) in women with a family history of diabetes.

RESEARCH DESIGN AND METHODS

This was a randomized controlled trial that examined whether inositol from the first antenatal visit prevents GDM. The trial was carried out in a single-center tertiary referral center. Women with a family history of diabetes were enrolled at the first antenatal visit. They were randomized to the intervention group, which received a combination of 1,100 mg myo-inositol, 27.6 mg D-chiro-inositol, and 400 μg folic acid, or to the control group, which received 400 μg folic acid only. All women had an oral glucose tolerance test between 24 and 28 weeks' gestation. The primary end point was the incidence of GDM. Statistical analysis was carried out using SPSS Statistical Package version 20.

RESULTS

Two hundred forty women, 120 in each arm, were recruited between January 2014 and July 2015. There were no differences in characteristics between the groups. The incidence of GDM was 23.3% (n = 28) in the intervention group compared with 18.3% (n = 22) in the control group (P = 0.34). The mean fasting plasma glucose at the glucose tolerance test was 81 mg/dL in both groups.

CONCLUSIONS

Commencing an inositol combination in early pregnancy did not prevent GDM in women with a family history of diabetes. Further studies are required to examine whether inositol supplements at varying doses may prevent GDM.

Pyruvate dehydrogenase complex in cerebral ischemia-reperfusion injury

Pyruvate dehydrogenase (PDH) complex is a mitochondrial matrix enzyme that serves a critical role in the conversion of anaerobic to aerobic cerebral energy. The regulatory complexity of PDH, coupled with its significant influence in brain metabolism, underscores its susceptibility to, and significance in, ischemia-reperfusion injury. Here, we evaluate proposed mechanisms of PDH-mediated neurodysfunction in stroke, including oxidative stress, altered regulatory enzymatic control, and loss of PDH activity. We also describe the neuroprotective influence of antioxidants, dichloroacetate, acetyl-L-carnitine, and combined therapy with ethanol and normobaric oxygen, explained in relation to PDH modulation. Our review highlights the significance of PDH impairment in stroke injury through an understanding of the mechanisms by which it is modulated, as well as an exploration of neuroprotective strategies available to limit its impairment.

Putative Key Role of Inositol Messengers in Endothelial Cells in Preeclampsia

Immunological alterations, endothelial dysfunction, and insulin resistance characterize preeclampsia. Endothelial cells hold the key role in the pathogenesis of this disease. The signaling pathways mediating these biological abnormalities converge on PKB/Akt, an intracellular kinase regulating cell survival, proliferation, and metabolism. Inositol second messengers are involved in metabolic and cell signaling pathways and are highly expressed during preeclampsia. Intracellular action of these molecules is deeply affected by zinc, manganese, and calcium. To evaluate the pathophysiological significance, we present the response of the intracellular pathways of inositol phosphoglycans involved in cellular metabolism and propose a link with the disease.

Lactic acidosis treatment by nanomole level of spermidine in an animal model

Lactic acidosis occurs in a number of clinical conditions, e.g. in surgeries, orthotopic liver transplant, and anesthetic agent administration, which has deleterious effects on the patient's survival. The most rational therapy for these patients, the sodium bicarbonate administration, cannot prevent those accompanying deficiencies and may actually be harmful. In addition, tromethamine adjusts the blood pH, it does not affect the lactate accumulation. Therefore, discovery of a therapeutic agent is still a major unsolved problem. In this study, the rats were divided into different groups and lactic acidosis type B was induced in them. Then, the effect of different injection doses of spermidine (0-20nmol) on lactic acidosis was analyzed by measuring the lactate level and pH in the rat blood samples. The results showed that spermidine effectively and simultaneously inhibited the lactate and pyruvate accumulations, and also adjusted the pH of bloodstream. On the other hand, it has been shown (Damuni et al., 1984; Rahmatullah and Roche, 1988) that spermidine increases the activity of phosphatase, leading to prevention of lactate accumulation. The results indicate that administration of only nanomole level of spermidine may be the best treatment in the liver transplant and other patients suffering from lactic acidosis type B.

Chemical biology of glycosylphosphatidylinositol anchors

Glycosylphosphatidylinositols (GPIs) are complex glycolipids that are covalently linked to the C-terminus of proteins as a posttranslational modification. They anchor the attached protein to the cell membrane and are essential for normal functioning of eukaryotic cells. GPI-anchored proteins are structurally and functionally diverse. Many GPIs have been structurally characterized but comprehension of their biological functions, beyond the simple physical anchoring, remains largely speculative. Work on functional elucidation at a molecular level is still limited. This Review focuses on the roles of GPI unraveled by using synthetic molecules and summarizes the structural diversity of GPIs, as well as their biological and chemical syntheses.

Herbal constituent sequoyitol improves hyperglycemia and glucose intolerance by targeting hepatocytes, adipocytes, and β-cells

The prevalence of insulin resistance and type 2 diabetes increases rapidly; however, treatments are limited. Various herbal extracts have been reported to reduce blood glucose in animals with either genetic or dietary type 2 diabetes; however, plant extracts are extremely complex, and leading compounds remain largely unknown. Here we show that 5-O-methyl-myo-inositol (also called sequoyitol), a herbal constituent, exerts antidiabetic effects in mice. Sequoyitol was chronically administrated into ob/ob mice either orally or subcutaneously. Both oral and subcutaneous administrations of sequoyitol decreased blood glucose, improved glucose intolerance, and enhanced insulin signaling in ob/ob mice. Sequoyitol directly enhanced insulin signaling, including phosphorylation of insulin receptor substrate-1 and Akt, in both HepG2 cells (derived from human hepatocytes) and 3T3-L1 adipocytes. In agreement, sequoyitol increased the ability of insulin to suppress glucose production in primary hepatocytes and to stimulate glucose uptake into primary adipocytes. Furthermore, sequoyitol improved insulin signaling in INS-1 cells (a rat β-cell line) and protected INS-1 cells from streptozotocin- or H₂O₂-induced injury. In mice with streptozotocin-induced β-cell deficiency, sequoyitol treatments increased plasma insulin levels and decreased hyperglycemia and glucose intolerance. These results indicate that sequoyitol, a natural, water-soluble small molecule, ameliorates hyperglycemia and glucose intolerance by increasing both insulin sensitivity and insulin secretion. Sequoyitol appears to directly target hepatocytes, adipocytes, and β-cells. Therefore, sequoyitol may serve as a new oral diabetes medication.

Metabolic and molecular action of Trigonella foenum-graecum (fenugreek) and trace metals in experimental diabetic tissues

Diabetes mellitus is a heterogeneous metabolic disorder characterized by hyperglycaemia resulting in defective insulin secretion, resistance to insulin action or both. The use of biguanides, sulphonylurea and other drugs are valuable in the treatment of diabetes mellitus; their use, however, is restricted by their limited action, pharmacokinetic properties, secondary failure rates and side effects. Trigonella foenum-graecum, commonly known as fenugreek, is a plant that has been extensively used as a source of antidiabetic compounds from its seeds and leaf extracts. Preliminary human trials and animal experiments suggest possible hypoglycaemic and antihyperlipedemic properties of fenugreek seed powder taken orally. Our results show that the action of fenugreek in lowering blood glucose levels is almost comparable to the effect of insulin. Combination with trace metal showed that vanadium had additive effects and manganese had additive effects with insulin on in vitro system in control and diabetic animals of young and old ages using adipose tissue. The Trigonella and vanadium effects were studied in a number of tissues including liver, kidney, brain peripheral nerve, heart, red blood cells and skeletal muscle. Addition of Trigonella to vanadium significantly removed the toxicity of vanadium when used to reduce blood glucose levels. Administration of the various combinations of the antidiabetic compounds to diabetic animals was found to reverse most of the diabetic effects studied at physiological, biochemical, histochemical and molecular levels. Results of the key enzymes of metabolic pathways have been summarized together with glucose transporter, Glut-4 and insulin levels. Our findings illustrate and elucidate the antidiabetic/insulin mimetic effects of Trigonella, manganese and vanadium.

D-chiro-inositol glycans in insulin signaling and insulin resistance

Classical actions of insulin involve increased glucose uptake from the bloodstream and its metabolism in peripheral tissues, the most important and relevant effects for human health. However, nonoxidative and oxidative glucose disposal by activation of glycogen synthase (GS) and mitochondrial pyruvate dehydrogenase (PDH) remain incompletely explained by current models for insulin action. Since the discovery of insulin receptor Tyr kinase activity about 25 years ago, the dominant paradigm for intracellular signaling by insulin invokes protein phosphorylation downstream of the receptor and its primary Tyr phosphorylated substrates-the insulin receptor substrate family of proteins. This scheme accounts for most, but not all, intracellular actions of insulin. Essentially forgotten is the previous literature and continuing work on second messengers generated in cells in response to insulin. Treatment and even prevention of diabetes and metabolic syndrome will benefit from a more complete elucidation of cellular-signaling events activated by insulin, to include the actions of second messengers such as glycan molecules that contain D-chiro-inositol (DCI). The metabolism of DCI is associated with insulin sensitivity and resistance, supporting the concept that second messengers have a role in responses to and resistance to insulin.

Age-related changes in the response of rat adipocytes to insulin: evidence for a critical role for inositol phosphoglycans and cAMP

Adipose tissue plays a pivotal role in ageing and longevity; many studies, both human and animal, have focussed on the effects of food limitation. Here we present a new model based on striking differences between two 'normal' inbred strains of albino Wistar rats the Charles River (CR) and Harlan Olac (HO) that have marked differences in age-related accumulation of fat and insulin-stimulated rates of glucose incorporation into lipid in the epididymal fat pads (EFP). The incorporation [U-(14)C]glucose into lipid by adipocytes showed that the CR group had a twofold higher basal rate of lipogenesis and a greater response to insulin in vitro, exceptionally, adipocytes from CR group maintained the high response to insulin to late adulthood while retaining the lower EFP weight/100 g body weight. Inositol phosphoglycan A-type (IPG-A), a putative insulin second messenger, was 3.5-fold higher and cAMP significantly lower per EFP in the CR versus HO groups. Plasma insulin levels were similar and plasma leptin higher in CR versus HO groups. The anomaly of a higher rate of lipogenesis and response to insulin and lower EFP weight in the CR group is interpreted as the resultant effect of a faster turnover of lipid and stimulating effect of leptin in raising fatty acid oxidation by muscle, potentially key to the lower accumulation of visceral fat. The metabolic profile of the CR strain provides a template that could be central to therapies that may lead to the lowering of both adipose and non-adipocyte lipid accumulation in humans in ageing.

The biological activity of structurally defined inositol glycans

BACKGROUND: The inositol glycans (IGs) are glycolipid-derived carbohydrates produced by insulin-sensitive cells in response to insulin treatment. IGs exhibit an array of insulin-like activities including stimulation of lipogenesis, glucose transport and glycogen synthesis, suggesting that they may be involved in insulin signal transduction. However, because the natural IGs are structurally heterogeneous and difficult to purify to homogeneity, an understanding of the relationship between structure and biological activity has relied principally on synthetic IGs of defined structure. DISCUSSION: This article briefly describes what is known about the role of IGs in signal transduction and reviews the specific biological activities of the structurally defined IGs synthesized and tested to date. CONCLUSION: A pharmacophore for IG activity begins to emerge from the reviewed data and the structural elements necessary for activity are summarized.