Project description:Skeletal muscle is the key site of peripheral insulin resistance in type 2 diabetes. Insulin-stimulated glucose uptake is decreased in differentiated diabetic myotubes in keeping with a retained genetic/epigenetic defect of insulin action. Microarray analysis was used to investigate differences in gene expression with differentiation in diabetic cultures compared to controls.
Project description:Type 2 diabetes is a complex disease associated with many underlying pathomechanisms. Epigenetic regulation of gene expression by DNA methylation has become increasingly recognized as an important component in the etiology of type 2 diabetes. We performed genome-wide methylome and transcriptome analysis in liver from severely obese patients with or without type 2 diabetes to discover aberrant pathways underlying the development of insulin resistance. We identified hypomethylation of five key genes involved in hepatic glycolysis, de novo lipogenesis and insulin resistance with concomitant increased mRNA expression and protein content. The CpG-site within the ATF-motif was hypomethylated in four of these genes in liver of non-diabetic and type 2 diabetic obese patients, suggesting epigenetic regulation of transcription by altered ATF-DNA binding. In conclusion, severely obese non-diabetic and type 2 diabetic patients have distinct alterations in the hepatic methylome and transcriptome and genes controlling glucose and lipid metabolism are hypomethylated at a regulatory site. Thus, obesity may epigenetically reprogram the liver towards increased lipid production and exacerbate the development of insulin resistance. To better understand the molecular mechanisms underlying the development of hepatic insulin resistance and type 2 diabetes at a molecular level, we performed a genome-wide methylome and transcriptome analysis of liver from non-obese metabolically healthy, obese non-diabetic and obese type 2 diabetic patients. Distinct DNA methylation and gene expression profiles were identified in liver from the obese and type 2 diabetic patients compared with the non-obese participants.
Project description:Brännmark2013 - Insulin signalling in human adipocytes (diabetic condition)
The paper describes insulin signalling in human adipocytes under normal and diabetic states using mathematical models based on experimental data. This model corresponds to insulin signalling under diabetic condtion
This model is described in the article:
Insulin Signaling in Type 2 Diabetes: EXPERIMENTAL AND MODELING ANALYSES REVEAL MECHANISMS OF INSULIN RESISTANCE IN HUMAN ADIPOCYTES.
Brännmark C, Nyman E, Fagerholm S, Bergenholm L, Ekstrand EM, Cedersund G, Strålfors P.
J Biol Chem. 2013 Apr 5;288(14):9867-80.
Abstract:
Type 2 diabetes originates in an expanding adipose tissue that for unknown reasons becomes insulin resistant. Insulin resistance reflects impairments in insulin signaling, but mechanisms involved are unclear because current research is fragmented. We report a systems level mechanistic understanding of insulin resistance, using systems wide and internally consistent data from human adipocytes. Based on quantitative steady-state and dynamic time course data on signaling intermediaries, normally and in diabetes, we developed a dynamic mathematical model of insulin signaling. The model structure and parameters are identical in the normal and diabetic states of the model, except for three parameters that change in diabetes: (i) reduced concentration of insulin receptor, (ii) reduced concentration of insulin-regulated glucose transporter GLUT4, and (iii) changed feedback from mammalian target of rapamycin in complex with raptor (mTORC1). Modeling reveals that at the core of insulin resistance in human adipocytes is attenuation of a positive feedback from mTORC1 to the insulin receptor substrate-1, which explains reduced sensitivity and signal strength throughout the signaling network. Model simulations with inhibition of mTORC1 are comparable with experimental data on inhibition of mTORC1 using rapamycin in human adipocytes. We demonstrate the potential of the model for identification of drug targets, e.g. increasing the feedback restores insulin signaling, both at the cellular level and, using a multilevel model, at the whole body level. Our findings suggest that insulin resistance in an expanded adipose tissue results from cell growth restriction to prevent cell necrosis.
This model is hosted on BioModels Database
and identified
by: MODEL1304160000
.
To cite BioModels Database, please use: BioModels Database: An enhanced, curated and annotated resource
for published quantitative kinetic models
.
To the extent possible under law, all copyright and related or
neighbouring rights to this encoded model have been dedicated to the public
domain worldwide. Please refer to CC0 Public Domain
Dedication
for more information.
Project description:Obesity-related insulin resistance represents the core component of the so-called Metabolic Syndrome, ultimately promoting glucose intolerance, pancreatic beta cell failure, and overt type 2 diabetes 1 2. Based on substantial side effects of existing pharmacological approaches, efficient and safe insulin sensitization and glucose control remain critical therapeutic aims to prevent diabetic late complications. Here, we identify Transforming Growth Factor beta-like Stimulated Clone (TSC) 22 D4 as a critical molecular determinant of insulin signaling and glucose handling. Hepatocyte-specific inactivation of TSC22D4 enhanced insulin signaling in liver and skeletal muscle, while hepatic TSC22D4 overexpression blunted insulin tissue responses. Consequently, hepatic TSC22D4 inhibition both prevented and reversed hyperglycemia, glucose intolerance, and insulin resistance in various diabetes mouse models, respectively. TSC22D4 was found to exert its effects on systemic glucose homeostasis –in large parts- through the transcriptional regulation of the small secretory protein lipocalin (LCN) 13 as demonstrated by chromatin recruitment and genetic rescue experiments in vivo. As hepatic TSC22D4 levels were found to be elevated in human diabetic patients, correlating with decreased insulin sensitivity and hyperglycemia, our results establish the inhibition of TSC22D4 as an attractive insulin sensitizing option in diabetes therapy.
Project description:Obesity-related insulin resistance represents the core component of the so-called Metabolic Syndrome, ultimately promoting glucose intolerance, pancreatic beta cell failure, and overt type 2 diabetes 1 2. Based on substantial side effects of existing pharmacological approaches, efficient and safe insulin sensitization and glucose control remain critical therapeutic aims to prevent diabetic late complications 3. Here, we identify Transforming Growth Factor beta-like Stimulated Clone (TSC) 22 D4 as a critical molecular determinant of insulin signaling and glucose handling. Hepatocyte-specific inactivation of TSC22D4 enhanced insulin signaling in liver and skeletal muscle, while hepatic TSC22D4 overexpression blunted insulin tissue responses. Consequently, hepatic TSC22D4 inhibition both prevented and reversed hyperglycemia, glucose intolerance, and insulin resistance in various diabetes mouse models, respectively. TSC22D4 was found to exert its effects on systemic glucose homeostasis - in large parts - through the transcriptional regulation of the small secretory protein lipocalin (LCN) 13 as demonstrated by chromatin recruitment and genetic rescue experiments in vivo. As hepatic TSC22D4 levels were found to be elevated in human diabetic patients, correlating with decreased insulin sensitivity and hyperglycemia, our results establish the inhibition of TSC22D4 as an attractive insulin sensitizing option in diabetes therapy.
Project description:Brännmark2013 - Insulin signalling in human adipocytes (normal condition)
The paper describes insulin signalling in human adipocytes under normal and diabetic states using mathematical models based on experimental data. This model corresponds to insulin signalling under normal condtion
This model is described in the article:
Insulin Signaling in Type 2 Diabetes: EXPERIMENTAL AND MODELING ANALYSES REVEAL MECHANISMS OF INSULIN RESISTANCE IN HUMAN ADIPOCYTES.
Brännmark C, Nyman E, Fagerholm S, Bergenholm L, Ekstrand EM, Cedersund G, Strålfors P.
J Biol Chem. 2013 Apr 5;288(14):9867-80.
Abstract:
Type 2 diabetes originates in an expanding adipose tissue that for unknown reasons becomes insulin resistant. Insulin resistance reflects impairments in insulin signaling, but mechanisms involved are unclear because current research is fragmented. We report a systems level mechanistic understanding of insulin resistance, using systems wide and internally consistent data from human adipocytes. Based on quantitative steady-state and dynamic time course data on signaling intermediaries, normally and in diabetes, we developed a dynamic mathematical model of insulin signaling. The model structure and parameters are identical in the normal and diabetic states of the model, except for three parameters that change in diabetes: (i) reduced concentration of insulin receptor, (ii) reduced concentration of insulin-regulated glucose transporter GLUT4, and (iii) changed feedback from mammalian target of rapamycin in complex with raptor (mTORC1). Modeling reveals that at the core of insulin resistance in human adipocytes is attenuation of a positive feedback from mTORC1 to the insulin receptor substrate-1, which explains reduced sensitivity and signal strength throughout the signaling network. Model simulations with inhibition of mTORC1 are comparable with experimental data on inhibition of mTORC1 using rapamycin in human adipocytes. We demonstrate the potential of the model for identification of drug targets, e.g. increasing the feedback restores insulin signaling, both at the cellular level and, using a multilevel model, at the whole body level. Our findings suggest that insulin resistance in an expanded adipose tissue results from cell growth restriction to prevent cell necrosis.
This model is hosted on BioModels Database
and identified
by: MODEL1304190000
.
To cite BioModels Database, please use: BioModels Database: An enhanced, curated and annotated resource
for published quantitative kinetic models
.
To the extent possible under law, all copyright and related or
neighbouring rights to this encoded model have been dedicated to the public
domain worldwide. Please refer to CC0 Public Domain
Dedication
for more information.
Project description:Type 2 diabetes mellitus (DM) is characterized by insulin resistance and pancreatic beta-cell dysfunction. In high-risk subjects, the earliest detectable abnormality is insulin resistance in skeletal muscle. Impaired insulin-mediated signaling, gene expression, and glycogen synthesis, and accumulation of intramyocellular triglycerides have all been linked with insulin resistance, but no specific defect responsible for insulin resistance and DM has been identified in humans. To identify genes potentially important in the pathogenesis of DM, we analyzed gene expression in skeletal muscle from healthy metabolically characterized nondiabetic (family history negative and positive for DM) and diabetic Mexican-American subjects. We demonstrate that insulin resistance and DM associate with reduced expression of multiple nuclear respiratory factor-1 (NRF-1)-dependent genes encoding key enzymes in oxidative metabolism and mitochondrial function. While NRF-1 expression is decreased only in diabetic subjects, expression of both PPARg coactivator 1-alpha and -beta (PGC1-a/PPARGC1, and PGC1-b/PERC), coactivators of NRF-1 and PPARg-dependent transcription, is decreased in both diabetic subjects and family history positive nondiabetic subjects. Decreased PGC1 expression may be responsible for decreased expression of NRFdependent genes, leading to the metabolic disturbances characteristic of insulin resistance and DM.
Project description:Obesity-related insulin resistance represents the core component of the so-called Metabolic Syndrome, ultimately promoting glucose intolerance, pancreatic beta cell failure, and overt type 2 diabetes 1 2. Based on substantial side effects of existing pharmacological approaches, efficient and safe insulin sensitization and glucose control remain critical therapeutic aims to prevent diabetic late complications 3. Here, we identify Transforming Growth Factor beta-like Stimulated Clone (TSC) 22 D4 as a critical molecular determinant of insulin signaling and glucose handling. Hepatocyte-specific inactivation of TSC22D4 enhanced insulin signaling in liver and skeletal muscle, while hepatic TSC22D4 overexpression blunted insulin tissue responses. Consequently, hepatic TSC22D4 inhibition both prevented and reversed hyperglycemia, glucose intolerance, and insulin resistance in various diabetes mouse models, respectively. TSC22D4 was found to exert its effects on systemic glucose homeostasis - in large parts - through the transcriptional regulation of the small secretory protein lipocalin (LCN) 13 as demonstrated by chromatin recruitment and genetic rescue experiments in vivo. As hepatic TSC22D4 levels were found to be elevated in human diabetic patients, correlating with decreased insulin sensitivity and hyperglycemia, our results establish the inhibition of TSC22D4 as an attractive insulin sensitizing option in diabetes therapy. 28 BKS.Cg-Dock7m +/+ Leprdb/J (000642) mice (12 week old ) were divided to 4 forms of treatment (n=7 per treatment group) consisting of 4 different shRNA adenoviruses (reference sample: control shRNA), LCN13 (LCN13 shRNA), TSC22D4 (TSC22D4 shRNA), TSC22D4 plus LCN13 (TSC22D4+LCN13 shRNA). 1 week after shRNA injection animals were sacrificed, liver, abdominal fat tissue, gastrocnemius tissue was immediately snap frozen. 3 representative animals of each treatment group were selected for microarray analysis (abdominal fat tissue).
Project description:There has been an incresing body of epidemiologic and biochemical evidence implying the role of cerebral insulin resistance in Alzheimer-type dementia. For a better understanding of the insulin effect on the central nervous system we performed microarray-based gene expression profiling in the hippocampus, striatum and prefrontal cortex of streptozotocin-induced and spontaneously diabetic Goto-Kakizaki rats as model animals for type 1 and type 2 diabetes, respectively. Following pathway analysis and validation of gene lists by RT-PCR, 30 genes from hippocampus, such as the inhibitory neuropeptide galanin, synuclein gamma and uncoupling protein 2, and 22 genes from the prefrontal cortex, e.g. galanin receptor 2, protein kinase gamma and epsilon, ABCA1, CD47 and the RET protooncogene, were found to exhibit altered expression levels in type 2 diabetic model animals in comparison to non-diabetic control animals. These gene lists proved to be partly overlapping and encompassed genes related to neurotransmission, lipidmetabolism, neuronal development, insulin secretion, oxidative damage and DNA repair. On the other hand, no significant alterations were found in the transcriptomes of the corpus sriatum in the same animals. Changes in the cerebral gene expression profiles seemed to be specific for the type 2 diabetic model, as no such alterations were found in streptozotocin-treated animals. According to our knowledge this is the first characterization of the whole-genome expression changes of specific brain regions in a diabetic model. Our findings shed light on the complex role of insulin signaling in fine-tuning brain functions, and provide further experimental evidence in support of the recently elaborated theory of type 3diabetes. Experiments were performed with 9 animals from each group. Wistar rats (control), streptoztocin-treated Wistar rats (type 1 diabetes) and Goto-Kakizaki rats (type 2 diabetes). The brain was removed and the striatum, hippocampus and prefrontal cortex were dissected. Samples from 3-3 identically treated animals were pooled. That means, 3 biological parallels were prepared from each brain region of type 1 or type 2 diabetic and control animals, amounting to a total of 27 different pooled samples.
Project description:Endurance exercise training has been shown to decrease whole-body and skeletal muscle insulin resistance and increase glucose tolerance in conditions of both pre-diabetes and overt type 2 diabetes. However, the adaptive responses in skeletal muscle at the molecular and genetic level for these beneficial effects of exercise training have not been clearly established in an animal model of pre-diabetes. The present study identifies alterations in skeletal muscle gene expression that occur with exercise training in pre-diabetic, insulin-resistant obese Zucker (fa/fa) rats and insulin-sensitive lean Zucker (Fa/-) rats. Treadmill running for up to 4 weeks caused significant enhancements of glucose tolerance as assessed by the integrated area under the curve for glucose (AUCg) during an oral glucose tolerance test in both lean and obese animals. Using microarray analysis, a set of only 12 genes was identified as both significantly altered (>1.5-fold change relative to sedentary controls; p<0.05) and significantly correlated (p<0.05) with the AUCg. Two of these genes, peroxisome proliferator-activated receptor-g coactivator 1a (PGC-1a) and the z-isoform of protein kinase C (PKC-z), have known involvement in the regulation of skeletal muscle glucose transport. We confirmed that protein expression levels of PGC-1a and PKC-z were positively correlated with the mRNA expression levels for these two genes. Overall, this study has identified a limited number of genes in soleus muscle of lean and obese Zucker rats that are associated with decreased insulin resistance and increase glucose tolerance following endurance exercise training. These findings could guide the development of pharmaceutical M-^Sexercise mimeticsM-^T in the treatment of insulin-resistant, pre-diabetic or overtly type 2 diabetic individuals.