Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0011849 (diabetes)
 277,896 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The Phosphatidylinositol-3 kinase/Protein Kinase B (PI3K/PKB) signaling pathway controls growth, metabolism, and lifespan in animals, and deregulation of its activity is associated with diabetes and cancer in humans. Here, we describe Susi, a coiled-coil domain protein that acts as a negative regulator of insulin signaling in Drosophila. Whereas loss of Susi function increases body size, overexpression of Susi reduces growth. We provide genetic evidence that Susi negatively regulates dPI3K activity. Susi directly binds to dP60, the regulatory subunit of dPI3K. Since Susi has no overt similarity to known inhibitors of PI3K/PKB signaling, it defines a novel mechanism by which this signaling cascade is kept in check. The fact that Susi is expressed in a circadian rhythm, with highest levels during the night, suggests that Susi attenuates insulin signaling during the fasting period.
 ...
PMID:Susi, a negative regulator of Drosophila PI3-kinase. 1593 72

Second-generation antipsychotic agents (SGAs) are increasingly replacing first-generation antipsychotic agents due to their superior activity against the negative symptoms of schizophrenia, decreased extrapyramidal symptoms and better tolerability. However, some SGAs are associated with adverse metabolic effects as significant weight gain, lipid disorders and diabetes mellitus. The pathogenesis of SGA-induced disturbances of glucose homeostasis is unclear. In vivo studies suggest a direct influence of SGAs on peripheral insulin resistance. To this end, we analyzed whether olanzapine might alter glycogen synthesis and the insulin-signaling cascade in L6 myotubes. Glycogen content was diminished in a dose- and time-dependent manner. Within the insulin-signaling cascade IRS-1 tyrosine phosphorylation was induced several fold by insulin and was diminished by preincubation with olanzapine. IRS-1-associated PI3K activity was stimulated by insulin three-fold in L6 myotubes. Olanzapine inhibited insulin-stimulated IRS-1-associated PI3K activity in a dose-dependent manner. Protein mass of AKT, GSK-3 and GS was unaltered, whereas phosphorylation of AKT and GSK-3 was diminished, and pGS was increased. Finally, we compared olanzapine with amisulpride, an SGA clinically not associated with the induction of diabetes mellitus. Glycogen content was diminished in olanzapine-preincubated L6 cells, whereas this effect was not observed under the amisulpride conditions. We conclude that olanzapine impairs glycogen synthesis via inhibition of the classical insulin-signaling cascade and that this inhibitory effect may lead to the induction of insulin resistance in olanzapine-treated patients.
 ...
PMID:Olanzapine impairs glycogen synthesis and insulin signaling in L6 skeletal muscle cells. 1655 Feb 12

Insulin and cholesterol play important roles in basic metabolic processes in peripheral tissues. Both insulin and cholesterol can also act as signalling molecules in the central nervous system that participate in neuronal function, memory and neurodegenerative diseases. A high-cholesterol diet improves spatial memory in experimental animals. beta-Amyloid, the toxic peptide in neurons of AD (Alzheimer's disease) patients, binds cholesterol and catalyses its oxidation to 7beta-hydroxycholesterol, a highly toxic oxysterol that is a potent inhibitor of alpha-PKC (alpha-protein kinase C), an enzyme critical in memory consolidation and synaptic plasticity and implicated in AD. Oxidized cholesterol also can act as a second messenger for insulin. Oxidized low-density lipoprotein inhibits insulin-dependent phosphorylation of the signalling kinases ERK (extracellular-signal-regulated kinase) and PKB/Akt. In sporadic AD patients, insulin levels are decreased, suggesting links between AD and diabetes. Insulin signalling is also important in synaptic plasticity. Insulin receptors are up-regulated and undergo translocation after spatial learning. Insulin modulates the activity of excitatory and inhibitory receptors including the glutamate and gamma-aminobutyric acid receptors and activates two biochemical pathways: the shc-ras-mitogen-activated protein kinase pathway and the PI3K (phosphoinositide 3-kinase)/PKC pathway, both of which are involved in memory processing. These findings point to a convergence at the biochemical level between pathways involved in AD and those important for normal memory.
 ...
PMID:Insulin and cholesterol pathways in neuronal function, memory and neurodegeneration. 1624 39

Stress signals that impair the function of the endoplasmic reticulum (ER) can lead to an accumulation of unfolded proteins in the ER causing cell death. Recent studies have indicated that ER stress contributes to several diseases such as neurodegenerative disorders or diabetes. In the present study, we found that Akt down-regulation is important for inducing CHOP expression, an ER stress-induced transcription factor. Treatment with tunicamycin or thapsigargin, ER stress inducers, caused dephosphorylation of Akt from 12 to 24 h and induced cell death. Interestingly, treatment with a PI3K inhibitor alone induced CHOP expression and caused cell death. However, a MEK1 inhibitor induced neither CHOP expression nor cell death. These results indicate that the inactivation of Akt by ER stress induces CHOP expression and causes cell death. Therefore, Akt plays an important role in ER stressed condition and may have important implications for understanding ER stress-related diseases.
 ...
PMID:PI3K-Akt inactivation induced CHOP expression in endoplasmic reticulum-stressed cells. 1637 64

To investigate the role of brain insulin action in the pathogenesis and treatment of diabetes, we asked whether neuronal insulin signaling is required for glucose-lowering during insulin treatment of diabetes. Hypothalamic signaling via the insulin receptor substrate-phosphatidylinositol 3-kinase (IRS-PI3K) pathway, a key intracellular mediator of insulin action, was reduced in rats with uncontrolled diabetes induced by streptozotocin (STZ-DM). Further, infusion of a PI3K inhibitor into the third cerebral ventricle of STZ-DM rats prior to peripheral insulin injection attenuated insulin-induced glucose lowering by approximately 35%-40% in both acute and chronic insulin treatment paradigms. Conversely, increased PI3K signaling induced by hypothalamic overexpression of either IRS-2 or protein kinase B (PKB, a key downstream mediator of PI3K action) enhanced the glycemic response to insulin by approximately 2-fold in STZ-DM rats. We conclude that hypothalamic insulin signaling via the IRS-PI3K pathway is a key determinant of the response to insulin in the management of uncontrolled diabetes.
 ...
PMID:Insulin action in the brain contributes to glucose lowering during insulin treatment of diabetes. 1639 6

Upper gastrointestinal dysfunction occurs frequently in diabetes and potentially contributes to both abdominal symptoms and impaired glycemic control; conversely, variations in blood glucose concentration reversibly affect gut motility in humans. In this issue of the JCI, Anitha et al. report apoptosis of rodent enteric neurons under hyperglycemic conditions, both in vitro and in vivo, associated with impaired PI3K activity and preventable by glial cell line-derived neurotrophic factor. These observations add to recent insights gained from animal models regarding the etiology of diabetic gastrointestinal dysfunction, but investigators must strive to translate animal data to human diabetes.
 ...
PMID:Gastrointestinal motility and glycemic control in diabetes: the chicken and the egg revisited? 1645 21

In obesity and diabetes, the ability of hypothalamic neurons to sense and transduce changes in leptin and insulin levels is compromised. The effects of both hormones require intracellular signalling via the PI3-kinase pathway, which is inhibited by the phosphatase PTEN. We show that leptin-stimulated F-actin depolymerization in mouse hypothalamic cells is inhibited by PTEN, a process involving independent effects of both its lipid and protein phosphatase activities. Potentially mediating this F-actin depolymerization, leptin, but not insulin, stimulated the phosphorylation of PTEN in a CK2 dependent manner, and inhibited its phosphatase activity. Similarly, hyperpolarization of mouse pancreatic beta-cells by leptin also requires coincident PtdIns(3,4,5)P3 generation and actin depolymerization, and could be inhibited by mechanisms requiring both the lipid and protein phosphatase activities of PTEN. These results demonstrate a critical role for PTEN in leptin signalling and indicate a mechanism by which leptin and insulin can produce PI3K dependent differential cellular outputs.
 ...
PMID:A novel leptin signalling pathway via PTEN inhibition in hypothalamic cell lines and pancreatic beta-cells. 1667 53

Gene regulation by transcriptional and post-translational mechanisms is implicated in the regulation of cellular homeostasis. Transcriptional deregulation has been largely documented in the etiology of diseases such as cancer, obesity and diabetes. During the past decade, the control of translation initiation by the PI3K/Akt/mTOR pathway in the development of these pathologies has been documented. Rapamycin, a specific inhibitor of mTOR, demonstrates considerable anti-proliferative activity against numerous cancer types. Recent studies also demonstrated that rapamycin may be beneficial in the treatment of obesity and diabetes. Rapamycin and its analogs seem destined for a promising future and will help in the development of novel therapeutic strategies.
 ...
PMID:[When translation arises from its TORpor]. 1668 20

Diabetic nephropathy (DN) is characterized by mesangial cell (MC) expansion and accumulation of extracellular matrix proteins. TGF-beta is increased in MC under diabetic conditions and in DN and activates key signaling pathways, including the phosphoinositide-3-kinase/Akt (PI3K/Akt) pathway. FoxO transcription factors play roles in cell survival and oxidative stress and are negatively regulated by Akt-mediated phosphorylation. We tested whether phosphorylation-mediated inactivation of FoxO3a by TGF-beta can mediate MC survival and oxidative stress. TGF-beta treatment significantly increased levels of p-Akt (activation) and p-FoxO3a (inactivation) in cultured MC. This FoxO3a inactivation was accompanied by significant decreases in the expression of two key FoxO3a target genes, the proapoptotic Bim and antioxidant manganese superoxide dismutase in MC. TGF-beta treatment triggered the nuclear exclusion of FoxO3a, significantly inhibited FoxO3a transcriptional activity, and markedly protected MC from apoptosis. A PI3K inhibitor blocked these TGF-beta effects. It is interesting that p-Akt and p-FoxO3A levels also were increased in renal cortical tissues from rats and mice at 2 wk after the induction of diabetes by streptozotocin, thus demonstrating in vivo significance. In summary, TGF-beta and diabetes can increase FoxO3a phosphorylation and transcriptional inactivation via PI3K/Akt. These new results suggest that Akt/FoxO pathway regulation may be a novel mechanism by which TGF-beta can induce unopposed MC survival and oxidant stress in early DN, thereby accelerating renal disease.
 ...
PMID:Role of the Akt/FoxO3a pathway in TGF-beta1-mediated mesangial cell dysfunction: a novel mechanism related to diabetic kidney disease. 1708 37

Peroxisome Proliferator-Activate Receptors (PPARs) are transcription factors belonging to the nuclear receptor superfamily. The three PPARs (alpha, beta/delta, and gamma) are distributed differently in the different organs. PPARalpha is most common in the liver, but also found in kidney, gut, skeletal muscle and adipose tissue, while PPARbeta/delta, is fairly ubiquitous; it may be found in body tissues and brain (for myelination process and lipid metabolism in the brain). PPARgamma has 3 isoforms, such as PPARgamma 1, PPARgamma 2, and PPARgamma 3. The syndrome-X was firstly coined by Reaven in 1988 and then to be provided in 1999 by the name : the metabolic syndrome-X. This metabolic syndrome represents a "Cluster" of metabolic disorders and cardiovascular risk factors which has been collected and summarized by the author and such a cluster includes: insulin resistance/hyperinsulinemia, central obesity, glucose intolerance/DM, atherogenic dyslipidemia (increase TG, decrease HDL-cholesterol, increase Apo-B, increase small dense LDL), hypertension, prothrombotic state (increase PAI-1, increase F-VII, increase fibrinogen, increase vWF, increase adhesion molecules), endothelial dysfunction, hyperuricemia, and increased hsC-RP and cytokines. The metabolic syndrome-X may lead to the development of T2DM and coronary heart disease (CHD); insulin resistance plays pivotal roles in the progression of such a syndrome and cardiovascular diseases. Improvement of Insulin Resistance, therefore, is most likely to reduce the high cardiovascular event rate in T2DM. It has been generally accepted that Insulin Resistance (detected by HOMA-R) and Acute Insulin Response = AIR (by HOMA-B) are both usually present in T2DM. The Thiazolidinedions (TZDs) are Insulin Sensitizers (e.g Rosiglitazone = ROS, Pioglitazone = PIO) introduced into clinical practice in 1997; clinical evidence data showed that TZDs improved both HOMA-R, and HOMA-B. PPARgamma can be activated by TZDs and it appears to be fundamental to the pathophysiology of diabetes mellitus i.e increase GLUT-4, increase glucokinase, decrease PEPCK, increase GLUT-4, and decreases production by fat cell of several mediators that may cause insulin resistance, such as TNFalpha and resistin. PPARgamma also mediates increased production of Adiponectin and the insulin signaling intermediate PI3K, and both actions lead to increase insulin sensitivity. A "dual PPARgamma-PPARalpha agonists" (e.g PIO, but ROS poorly activate PPARalpha) might lower glucose and modulate lipids. Thus, PIO, as a stronger "dual PPARgamma-PPARalpha agonists", shows an important therapeutic pathway in diabetes mellitus and cardiovascular diseases, even in metabolic syndrome. Current evidence suggests a close relationship between activation of PPARgamma and restoration of insulin sensitivity by reductions in TNFalpha and FFAs, and the enhancement of insulin stimulation of PI3-K Pathway and also increase adiponectin & decrease resistin.
 ...
PMID:New approach in the treatment of T2DM and metabolic syndrome (focus on a novel insulin sensitizer). 1711 68


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>