Project description:In the present study we tested the hypothesis that male and female rat livers respond differently to a change in nutrient availability or to insulin treatment. We compared hepatic gene expression, hepatic glycogen and glucose output, insulin sensitivity and amino acids, using healthy rats. Keywords: Hepatic gene expression, sex-differences
Project description:In the present study we tested the hypothesis that male and female rat livers respond differently to a change in nutrient availability or to insulin treatment. We compared hepatic gene expression, hepatic glycogen and glucose output, insulin sensitivity and amino acids, using healthy rats. Keywords: Hepatic gene expression, sex-differences Two-condition experiment. Biological replicates: 4 male rat livers from rats on a standard diet and 4 female rat livers from rats on a standard diet. One replicate per array.
Project description:Skeletal muscle is not only a primary site for glucose uptake and storage, but also a reservoir for amino acids stored as protein. How the metabolism of these two fuels is coordinated in skeletal muscle is incompletely understood. Here, we demonstrate that interferon regulatory factor 4 (IRF4) integrate glucose and amino acids flux by regulating glycogen synthesis and branched-chain-amino acid (BCAA) metabolism in skeletal muscle. Mice with IRF4 specifically knocked out in skeletal muscle (MI4KO) showed elevated plasma BCAAs and skeletal muscle glycogen content, decreased adiposity and body weight, along with increased energy expenditure, remarkable improvements in glucose and insulin tolerance, and protection from diet-induced obesity (DIO). Loss of IRF4 caused downregulation of the mitochondrial branched-chain aminotransferase isozyme (BCATm) in myocytes, which encodes for the enzyme catalyzing the first step of BCAA metabolism. Lack of IRF4 also led to the upregulation of protein targeting to glycogen (PTG), which is associated with enhanced mitochondrial Complex II activity and mitochondria number. Additionally, overexpression of IRF4 in skeletal muscle caused obesity and reduced exercise capacity. Mechanistically, we found that IRF4 directly regulates both BCATm and PTG expression, and that overexpression of BCATm can partially reverse the effects of IRF4 deletion. These studies establish IRF4 as a novel driver of both glucose and BCAA metabolism in skeletal muscle.
Project description:We have previously shown that in response to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-elicited NAFLD progression, central carbon, glutaminolysis and serine/folate metabolism are reprogrammed to support NADPH production and ROS defenses. To further investigate underlying dose-dependent responses associated with TCDD-induced fibrosis, female C57BL/6 mice were gavaged with TCDD every 4 days (d) for 28d or 92d. RNA-Seq, ChIP-Seq (2hr), and 28d metabolomic (urine, serum, and hepatic extract) analyses were conducted with complementary serum marker assessments at 92d. Additional vehicle and 30 µg/kg treatment groups were allowed to recover for 36d following the 92d treatment regimen to examine recovery from TCDD-elicited fibrosis. Histopathology revealed dose-dependent increases in hepatic fat accumulation, inflammation, and periportal collagen deposition at 92d, with increased fibrotic severity in the recovery group. Serum proinflammatory and profibrotic interleukins-1β, -2, -4, -6, and -10, as well as TNFα and IFNγ, exhibited dose-dependent induction. An increase in glucose tolerance was observed with a concomitant 3.0-fold decrease in hepatic glycogen linked to increased ascorbic acid biosynthesis and proline metabolism, consistent with increased fibrosis. RNA-Seq identified differential expression of numerous matrisome genes including an 8.8-fold increase in Tgfb2 indicating myofibroblast activation. Further analysis suggests reprogramming of glycogen, ascorbic acid, and amino acid metabolism in support of collagen deposition and the use of proline as a substrate for ATP production via the proline cycle. Conclusion: In addition to metabolic reprogramming in support of NADPH production for ROS defense, we demonstrate that glycogen, ascorbic acid, and amino acid metabolism are also reorganized to support remodeling of the extracellular matrix, progressing to hepatic fibrosis in response to chronic injury from TCDD.
Project description:Goals of the Study:; 1. Assess the scope of arginine-responsive hepatic gene expression using in vitro rat models. 2. Compare normal and tumorigenic cells; 3. Identify potentially novel genes and pathways that may be subject to amino acid (arginine) regulation; Background: We previously reported that mRNA levels of the tumor associated glycoprotein amino acid transporter TA1/LAT1/ CD98 light chain arginine increase in normal hepatic cells under low arginine conditions while levels are constitutive and high in hepatic tumor cells. This suggested LAT1 amino acid response was associated with the normal hepatic phenotype and lost in carcinogenesis and may impact cell growth and survival in the tumor microenvironment. We sought to investigate how many and what types of genes are responsive to a change in arginine levels over 18 hrs using an in vitro model system. Experimental design:; Differential gene expression was determined by microarrays using samples from triplicates of normal and transformed cells subjected to 18 hour arginine-deprivation compared to controls
Project description:We assessed the impact of glucose transporter Glut2 gene inactivation in adult mouse liver (LG2KO mice). This suppressed hepatic glucose uptake but not glucose output. In the fasted state, expression of carbohydrate responsive element-binding protein (ChREBP) and its glycolytic and lipogenic target genes was abnormally elevated. Feeding, energy expenditure, and insulin sensitivity were identical in LG2KO and control mice. Glucose tolerance was normal early after Glut2 inactivation but intolerance developed at later time. This was caused by progressive impairment of glucose-stimulated insulin secretion even though beta-cell mass and insulin content remained normal. Liver transcript profiling revealed a coordinate down-regulation of cholesterol biosynthesis genes in LG2KO mice. This was associated with reduced hepatic cholesterol in fasted mice and a 30 percent reduction in bile acid production. We showed that chronic bile acids or FXR agonist treatment of primary islets increases glucose-stimulated insulin secretion, an effect not seen in islets from fxr-/- mice. Collectively, our data show that glucose sensing by the liver controls beta-cell glucose competence, through a mechanism that likely depends on bile acid production and action on beta-cells. three replicates each of ps_ctrl_refed, ps_tamox_refed, ps_ctrl_fasted, ps_tamox_fasted
Project description:Postoperative insulin resistance refers to the phenomenon that the body’s glucose uptake stimulated by insulin is reduced due to stress effects such as trauma or the inhibitory effect of insulin on liver glucose output is weakened after surgery.
There is a clear link between postoperative insulin resistance and poor perioperative prognosis. Therefore, exploring interventions to reduce postoperative stress insulin resistance, stabilize postoperative blood glucose, and reduce postoperative complications are clinical problems that need to be solved urgently. In recent years, research on branched-chain amino acids and metabolic diseases has become a hot spot. Studies have found that in the rat model, preoperatively given a high branched-chain amino acid diet can inhibit postoperative insulin resistance and stabilize blood glucose levels. This research plan is to try to add branched-chain amino acids before surgery to observe the occurrence of postoperative insulin resistance in patients.
Project description:Medium-chain acyl-coenzyme A (CoA) dehydrogenase (MCAD) catalyzes crucial steps in mitochondrial fatty acid oxidation, a process that is of key relevance for maintenance of energy homeostasis, especially during high metabolic demand. To gain insight into the metabolic consequences of MCAD deficiency under these conditions, we compared hepatic carbohydrate metabolism in vivo in wild-type and MCAD-/- mice during fasting and during a lipopolysaccharide (LPS)-induced acute phase response (APR). MCAD-/- mice did not become more hypoglycemic on fasting or during the APR than wild-type mice did. Nevertheless, microarray analyses revealed increased hepatic peroxisome proliferator-activated receptor gamma coactivator-1a (Pgc-1a) and decreased peroxisome proliferator-activated receptor alpha (Ppar a) and pyruvate dehydrogenase kinase 4 (Pdk4) expression in MCAD-/- mice in both conditions,suggesting altered control of hepatic glucose metabolism. Quantitative flux measurements revealed that the de novo synthesis of glucose-6-phosphate (G6P) was not affected on fasting in MCAD-/- mice. During the APR, however, this flux was significantly decreased (-20%) in MCAD-/- mice compared with wild-type mice. Remarkably, newly formed G6P was preferentially directed toward glycogen in MCAD-/- mice under both conditions. Together with diminished de novo synthesis of G6P, this led to a decreased hepatic glucose output during the APR in MCAD-/- mice; de novo synthesis of G6P and hepatic glucose output were maintained in wild-type mice under both conditions. APR-associated hypoglycemia, which was observed in wild-type mice as well as MCAD-/- mice, was mainly due to enhanced peripheral glucose uptake. Conclusion: Our data demonstrate that MCAD deficiency in mice leads to specific changes in hepatic carbohydrate management on exposure to metabolic stress. This deficiency, however, does not lead to reduced de novo synthesis of G6P during fasting alone, which may be due to the existence of compensatory mechanisms or limited rate control of MCAD in murine mitochondrial fatty acid oxidation. Total RNA obtained from Liver ( 20 samples) , where comparing 4 groups, consisting out of 5 biological replicates, all groups where fasted for 12 hrs, and half of them where injected with LPS ( 100ug/20gr BW) or vehicle
Project description:Medium-chain acyl-coenzyme A (CoA) dehydrogenase (MCAD) catalyzes crucial steps in mitochondrial fatty acid oxidation, a process that is of key relevance for maintenance of energy homeostasis, especially during high metabolic demand. To gain insight into the metabolic consequences of MCAD deficiency under these conditions, we compared hepatic carbohydrate metabolism in vivo in wild-type and MCAD-/- mice during fasting and during a lipopolysaccharide (LPS)-induced acute phase response (APR). MCAD-/- mice did not become more hypoglycemic on fasting or during the APR than wild-type mice did. Nevertheless, microarray analyses revealed increased hepatic peroxisome proliferator-activated receptor gamma coactivator-1a (Pgc-1a) and decreased peroxisome proliferator-activated receptor alpha (Ppar a) and pyruvate dehydrogenase kinase 4 (Pdk4) expression in MCAD-/- mice in both conditions,suggesting altered control of hepatic glucose metabolism. Quantitative flux measurements revealed that the de novo synthesis of glucose-6-phosphate (G6P) was not affected on fasting in MCAD-/- mice. During the APR, however, this flux was significantly decreased (-20%) in MCAD-/- mice compared with wild-type mice. Remarkably, newly formed G6P was preferentially directed toward glycogen in MCAD-/- mice under both conditions. Together with diminished de novo synthesis of G6P, this led to a decreased hepatic glucose output during the APR in MCAD-/- mice; de novo synthesis of G6P and hepatic glucose output were maintained in wild-type mice under both conditions. APR-associated hypoglycemia, which was observed in wild-type mice as well as MCAD-/- mice, was mainly due to enhanced peripheral glucose uptake. Conclusion: Our data demonstrate that MCAD deficiency in mice leads to specific changes in hepatic carbohydrate management on exposure to metabolic stress. This deficiency, however, does not lead to reduced de novo synthesis of G6P during fasting alone, which may be due to the existence of compensatory mechanisms or limited rate control of MCAD in murine mitochondrial fatty acid oxidation.