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Insulin Signaling Pathway (insulin + signaling_pathway)
Selected AbstractsDisruption of insulin pathways alters trehalose level and abolishes sexual dimorphism in locomotor activity in DrosophilaDEVELOPMENTAL NEUROBIOLOGY, Issue 1 2006Yesser Hadj Belgacem Abstract Insulin signaling pathways are implicated in several physiological processes in invertebrates, including the control of growth and life span; the latter of these has also been correlated with juvenile hormone (JH) deficiency. In turn, JH levels have been correlated with sex-specific differences in locomotor activity. Here, the involvement of the insulin signaling pathway in sex-specific differences in locomotor activity was investigated in Drosophila. Ablation of insulin-producing neurons in the adult pars-intercerebralis was found to increase trehalosemia and to abolish sexual dimorphism relevant to locomotion. Conversely, hyper-insulinemia induced by insulin injection or by over-expression of an insulin-like peptide decreases trehalosemia but does not affect locomotive behavior. Moreover, we also show that in the head of adult flies, the insulin receptor (InR) is expressed only in the fat body surrounding the brain. While both male and female InR mutants are hyper-trehalosemic, they exhibit similar patterns of locomotor activity. Our results indicate that first, insulin controls trehalosemia in adults, and second, like JH, it controls sex-specific differences in the locomotor activity of adult Drosophila in a manner independent of its effect on trehalose metabolism. © 2005 Wiley Periodicals, Inc. J Neurobiol, 2006 [source] Integration of diverse inputs in the regulation of Caenorhabditis elegans DAF-16/FOXODEVELOPMENTAL DYNAMICS, Issue 5 2010Jessica N. Landis Abstract In a remarkably conserved insulin signaling pathway that is well-known for its regulation of longevity in worms, flies, and mammals, the major C. elegans effector of this pathway, DAF-16/FOXO, also modulates many other physiological processes. This raises the question of how DAF-16/FOXO chooses the correct targets to achieve the appropriate response in a particular context. Here, we review current knowledge of tissue-specificity and interacting partners that modulate DAF-16/FOXO functional output. Developmental Dynamics 239:1405,1412, 2010. © 2010 Wiley-Liss, Inc. [source] Disruption of insulin pathways alters trehalose level and abolishes sexual dimorphism in locomotor activity in DrosophilaDEVELOPMENTAL NEUROBIOLOGY, Issue 1 2006Yesser Hadj Belgacem Abstract Insulin signaling pathways are implicated in several physiological processes in invertebrates, including the control of growth and life span; the latter of these has also been correlated with juvenile hormone (JH) deficiency. In turn, JH levels have been correlated with sex-specific differences in locomotor activity. Here, the involvement of the insulin signaling pathway in sex-specific differences in locomotor activity was investigated in Drosophila. Ablation of insulin-producing neurons in the adult pars-intercerebralis was found to increase trehalosemia and to abolish sexual dimorphism relevant to locomotion. Conversely, hyper-insulinemia induced by insulin injection or by over-expression of an insulin-like peptide decreases trehalosemia but does not affect locomotive behavior. Moreover, we also show that in the head of adult flies, the insulin receptor (InR) is expressed only in the fat body surrounding the brain. While both male and female InR mutants are hyper-trehalosemic, they exhibit similar patterns of locomotor activity. Our results indicate that first, insulin controls trehalosemia in adults, and second, like JH, it controls sex-specific differences in the locomotor activity of adult Drosophila in a manner independent of its effect on trehalose metabolism. © 2005 Wiley Periodicals, Inc. J Neurobiol, 2006 [source] C-peptide makes a comebackDIABETES/METABOLISM: RESEARCH AND REVIEWS, Issue 5 2003John Wahren Proinsulin C-peptide was for long considered to be without biological activity of its own. New findings demonstrate, however, that it is capable of eliciting both molecular and physiological effects, suggesting that C-peptide is in fact a bioactive peptide. When administered in replacement doses to animal models or to patients with type 1 diabetes, C-peptide ameliorates diabetes-induced functional and structural changes in both the kidneys and the peripheral nerves. It augments blood flow in a number of tissues, notably skeletal muscle, myocardium, skin and nerve. These effects are thought to be mediated via a stimulatory influence on Na+,K+ -ATPase and on endothelial nitric oxide synthase. Specific binding of C-peptide to cell membranes of intact cells and to detergent-solubilized cellular components has been demonstrated, indicating the existence of cell-surface binding sites for C-peptide. A number of intracellular responses are elicited by C-peptide, including a rise in Ca2+ concentration and activation of MAP-kinase signaling pathways. Many but not all of C-peptide's intracellular effects can be inhibited by pertussis toxin, supporting the notion that C-peptide may interact via a G-protein-coupled receptor. Additional data suggest that C-peptide may interact synergistically also in the insulin signaling pathway. Combined, the available observations show conclusively that C-peptide is biologically active, even though its molecular mechanism of action is not as yet fully understood. The possibility that replacement of C-peptide in patients with type 1 diabetes may serve to retard or prevent the development of long-term complications should be evaluated. Copyright © 2003 John Wiley & Sons, Ltd. [source] Glucagon-like peptide-1 receptor is present on human hepatocytes and has a direct role in decreasing hepatic steatosis in vitro by modulating elements of the insulin signaling pathway,HEPATOLOGY, Issue 5 2010Nitika Arora Gupta Glucagon-like peptide 1 (GLP-1) is a naturally occurring peptide secreted by the L cells of the small intestine. GLP-1 functions as an incretin and stimulates glucose-mediated insulin production by pancreatic , cells. In this study, we demonstrate that exendin-4/GLP-1 has a cognate receptor on human hepatocytes and that exendin-4 has a direct effect on the reduction of hepatic steatosis in the absence of insulin. Both glucagon-like peptide 1 receptor (GLP/R) messenger RNA and protein were detected on primary human hepatocytes, and receptor was internalized in the presence of GLP-1. Exendin-4 increased the phosphorylation of 3-phosphoinositide-dependent kinase-1 (PDK-1), AKT, and protein kinase C , (PKC-,) in HepG2 and Huh7 cells. Small interfering RNA against GLP-1R abolished the effects on PDK-1 and PKC-,. Treatment with exendin-4 quantitatively reduced triglyceride stores compared with control-treated cells. Conclusion: This is the first report that the G protein,coupled receptor GLP-1R is present on human hepatocytes. Furthermore, it appears that exendin-4 has the same beneficial effects in vitro as those seen in our previously published in vivo study in ob/ob mice, directly reducing hepatocyte steatosis. Future use for human nonalcoholic fatty liver disease, either in combination with dietary manipulation or other pharmacotherapy, may be a significant advance in treatment of this common form of liver disease. (HEPATOLOGY 2010) [source] Updating the effects of fatty acids on skeletal muscleJOURNAL OF CELLULAR PHYSIOLOGY, Issue 1 2008Leonardo R. Silveira In this review we updated the fatty acid (FA) effects on skeletal muscle metabolism. Abnormal FA availability induces insulin resistance and accounts for several of its symptoms and complications. Efforts to understand the pathogenesis of insulin resistance are focused on disordered lipid metabolism and consequently its effect on insulin signaling pathway. We reviewed herein the FA effects on metabolism, signaling, regulation of gene expression and oxidative stress in insulin resistance. The elevated IMTG content has been associated with increased intracellular content of diacylglycerol (DAG), ceramides and long-chain acyl-coenzyme A (LCA-CoA). This condition has been shown to promote insulin resistance by interfering with phosphorylation of proteins of the insulin pathway including insulin receptor substrate-1/2 (IRS), phosphatidylinositol-3-kinase, (PI3-kinase) and protein kinase C. Although the molecular mechanism is not completely understood, elevated reactive oxygen (ROS) and nitrogen species (RNS) are involved in this process. Elevated ROS/RNS activates nuclear factor-kappaB (NFkB), which promotes the transcription of proinflammatory tumoral necrosis factor alpha (TNF,), decreasing the insulin response. Therefore, oxidative stress induced by elevated FA availability may constitute one of the major causes of insulin resistance in skeletal muscle. J. Cell. Physiol. 217: 1,12, 2008. © 2008 Wiley-Liss, Inc. [source] Novel EGF pathway regulators modulate C. elegans healthspan and lifespan via EGF receptor, PLC-,, and IP3R activationAGING CELL, Issue 4 2010Hiroaki Iwasa Summary Improving health of the rapidly growing aging population is a critical medical, social, and economic goal. Identification of genes that modulate healthspan, the period of mid-life vigor that precedes significant functional decline, will be an essential part of the effort to design anti-aging therapies. Because locomotory decline in humans is a major contributor to frailty and loss of independence and because slowing of movement is a conserved feature of aging across phyla, we screened for genetic interventions that extend locomotory healthspan of Caenorhabditis elegans. From a group of 54 genes previously noted to encode secreted proteins similar in sequence to extracellular domains of insulin receptor, we identified two genes for which RNAi knockdown delayed age-associated locomotory decline, conferring a high performance in advanced age phenotype (Hpa). Unexpectedly, we found that hpa-1 and hpa-2 act through the EGF pathway, rather than the insulin signaling pathway, to control systemic healthspan benefits without detectable developmental consequences. Further analysis revealed a potent role of EGF signaling, acting via downstream phospholipase C-,plc-3 and inositol-3-phosphate receptor itr-1, to promote healthy aging associated with low lipofuscin levels, enhanced physical performance, and extended lifespan. This study identifies HPA-1 and HPA-2 as novel negative regulators of EGF signaling and constitutes the first report of EGF signaling as a major pathway for healthy aging. Our data raise the possibility that EGF family members should be investigated for similar activities in higher organisms. [source] Endogenous cGMP regulates adult longevity via the insulin signaling pathway in Caenorhabditis elegansAGING CELL, Issue 4 2009Jeong-Hoon Hahm Summary G-proteins, including GPA-3, play an important role in regulating physiological responses in Caenorhabditis elegans. When confronted with an environmental stimulus such as dauer pheromone, or poor nutrients, C. elegans receives and integrates external signals through its nervous system (i.e. amphid neurons), which interprets and translates them into biological action. Here it is shown that a suppressed neuronal cGMP level caused by GPA-3 activation leads to a significant increase (47.3%) in the mean lifespan of adult C. elegans through forkhead transcription factor family O (FOXO)-mediated signal. A reduced neuronal cGMP level was found to be caused by an increased cGMP-specific phosphodiesterase activity at the transcriptional level. Our results using C. elegans mutants with specific deficits in TGF-, and FOXO RNAi system suggest a mechanism in that cGMP, TGF-,, and FOXO signaling interact to differentially produce the insulin-like molecules, ins-7 and daf-28, causing suppression of the insulin/IGF-1 pathway and promoting lifespan extension. Our findings provide not only a new mechanism of cGMP-mediated induction of longevity in adult C. elegans but also a possible therapeutic strategy for neuronal disease, which has been likened to brain diabetes. [source] Transcriptional changes in insulin- and lipid metabolism-related genes in the hippocampus of olfactory bulbectomized miceJOURNAL OF NEUROSCIENCE RESEARCH, Issue 14 2008Peter Gass Abstract Affymetrix chips were used to perform a hypothesis-free large-scale screening of transcripts in the hippocampus of olfactory bulbectomized mice, an established animal model of depression. Because only 11 transcripts were significantly changed, the statistically subsequent 25 transcripts below the significance level were additionally included in a first round of qRT-PCR evaluations. Furthermore, all 36 genes were then tested for mutual interactions or interactions with other molecules in a physiological context using PathwayArchitect software. Thirty of them were displayed in a network interacting with at least one partner molecule from the list or with other partner molecules known from the literature. All partner molecules from the most prominent 10 molecules of this network were then identified and put together into a new list. On those grounds, the hypothesis was made that metabolic network components of the insulin signaling pathway are perturbed in the disease. This pathway was subsequently tested by a second round of qRT-PCR, adding also a few additional candidate molecules belonging to this pathway. It turned out that the key target,FABP7,fell into the group of transcripts not significantly regulated within the chip data, and another key target,IRS1,did not show up in the chip experiments at all. In conclusion, our data reveal a problem with adhering to statistical significances in microarray experiments, insofar as molecules important for the disease may fall into the range of statistical noise. This approach may also be useful to find new targets for pharmacotherapy in affective disorders. © 2008 Wiley-Liss, Inc. [source] Gene expression analysis of BCR/ABL1-dependent transcriptional response reveals enrichment for genes involved in negative feedback regulationGENES, CHROMOSOMES AND CANCER, Issue 4 2008Petra Håkansson Philadelphia (Ph) chromosome-positive leukemia is characterized by the BCR/ABL1 fusion protein that affects a wide range of signal transduction pathways. The knowledge about its downstream target genes is, however, still quite limited. To identify novel BCR/ABL1-regulated genes we used global gene expression profiling of several Ph-positive and Ph-negative cell lines treated with imatinib. Following imatinib treatment, the Ph-positive cells showed decreased growth, viability, and reduced phosphorylation of BCR/ABL1 and STAT5. In total, 142 genes were identified as being dependent on BCR/ABL1-mediated signaling, mainly including genes involved in signal transduction, e.g. the JAK/STAT, MAPK, TGFB, and insulin signaling pathways, and in regulation of metabolism. Interestingly, BCR/ABL1 was found to activate several genes involved in negative feedback regulation (CISH, SOCS2, SOCS3, PIM1, DUSP6, and TNFAIP3), which may act to indirectly suppress the tumor promoting effects exerted by BCR/ABL1. In addition, several genes identified as deregulated upon BCR/ABL1 expression could be assigned to the TGFB and NFkB signaling pathways, as well as to reflect the metabolic adjustments needed for rapidly growing cells. Apart from providing important pathogenetic insights into BCR/ABL1 -mediated leukemogenesis, the present study also provides a number of pathways/individual genes that may provide attractive targets for future development of targeted therapies. This article contains Supplementary Material available at http://www.interscience.wiley.com/jpages/1045,2257/suppmat. © 2008 Wiley-Liss, Inc. [source] Molecular Mechanisms of Alcoholic Fatty LiverALCOHOLISM, Issue 2 2009Vishnudutt Purohit Alcoholic fatty liver is a potentially pathologic condition which can progress to steatohepatitis, fibrosis, and cirrhosis if alcohol consumption is continued. Alcohol exposure may induce fatty liver by increasing NADH/NAD+ ratio, increasing sterol regulatory element-binding protein-1 (SREBP-1) activity, decreasing peroxisome proliferator-activated receptor-, (PPAR-,) activity, and increasing complement C3 hepatic levels. Alcohol may increase SREBP-1 activity by decreasing the activities of AMP-activated protein kinase and sirtuin-1. Tumor necrosis factor-, (TNF-,) produced in response to alcohol exposure may cause fatty liver by up-regulating SREBP-1 activity, whereas betaine and pioglitazone may attenuate fatty liver by down-regulating SREBP-1 activity. PPAR-, agonists have potentials to attenuate alcoholic fatty liver. Adiponectin and interleukin-6 may attenuate alcoholic fatty liver by up-regulating PPAR-, and insulin signaling pathways while down-regulating SREBP-1 activity and suppressing TNF-, production. Recent studies show that paracrine activation of hepatic cannabinoid receptor 1 by hepatic stellate cell-derived endocannabinoids also contributes to the development of alcoholic fatty liver. Furthermore, oxidative modifications and inactivation of the enzymes involved in the mitochondrial and/or peroxisomal ,-oxidation of fatty acids could contribute to fat accumulation in the liver. [source] Association of common genetic variation in the insulin/IGF1 signaling pathway with human longevityAGING CELL, Issue 4 2009Ludmila Pawlikowska Summary The insulin/IGF1 signaling pathways affect lifespan in several model organisms, including worms, flies and mice. To investigate whether common genetic variation in this pathway influences lifespan in humans, we genotyped 291 common variants in 30 genes encoding proteins in the insulin/IGF1 signaling pathway in a cohort of elderly Caucasian women selected from the Study of Osteoporotic Fractures (SOF). The cohort included 293 long-lived cases (lifespan , 92 years (y), mean ± standard deviation (SD) = 95.3 ± 2.2y) and 603 average-lifespan controls (lifespan , 79y, mean = 75.7 ± 2.6y). Variants were selected for genotyping using a haplotype-tagging approach. We found a modest excess of variants nominally associated with longevity. Nominally significant variants were then replicated in two additional Caucasian cohorts including both males and females: the Cardiovascular Health Study and Ashkenazi Jewish Centenarians. An intronic single nucleotide polymorphism in AKT1, rs3803304, was significantly associated with lifespan in a meta-analysis across the three cohorts (OR = 0.78 95%CI = 0.68,0.89, adjusted P = 0.043); two intronic single nucleotide polymorphisms in FOXO3A demonstrated a significant lifespan association among women only (rs1935949, OR = 1.35, 95%CI = 1.15,1.57, adjusted P = 0.0093). These results demonstrate that common variants in several genes in the insulin/IGF1 pathway are associated with human lifespan. [source] The role of stress in ageing: research on the nematode, Caenorhabditis elegansBRITISH JOURNAL OF DERMATOLOGY, Issue 2005N. Ishii Summary The nematode Caenorhabditis elegans has proven a robust genetic model for studies of aging and the roles of stress. In this review we focus on the genetics of select long-lived and short-lived mutants of C. elegans that have proven useful in revealing the relationships that exist between oxidative stress and life span. The former are known to be controlled by an insulin/insulin-like signaling pathway, while the latter are affected by mitochondrial functions. [source] | |||||||||||||