Project description:We report the transcritional targets of transcription factor downstream of insulin signalling. We knocked down transcription factors under reduced insulin signalling in Caenorhabditis elegans and did transcriptom analysis. This study identified target genes interaction complexity in analogous genetic and experimental conditions. It aid in gaining insight into the new molecular mechanisms downstream of rIIS
Project description:Insulin and insulin-like growth factor signalling regulates a broad spectrum of growth and metabolic responses to a variety of internal and environmental stimuli. Such responses can be tailored so that changes in insulin signalling result in distinct physiological responses to different stimuli. For example, the inhibition of insulin-like signalling is key in the responses of the nematode C. elegans to both osmotic stress and starvation, but these two stresses result in responses that are both physiologically and molecularly distinct. How does reduced insulin-like signalling elicit different responses to different environmental stimuli? We report that neurohormonal signalling involving the C. elegans cytosolic sulfotransferase SSU-1 controls developmental arrest in response to osmotic stress but does not control the distinct developmental arrest that occurs in response to starvation. SSU-1 functions in a single pair of sensory neurons to control intercellular signalling -- likely by catalyzing the synthesis of a steroid hormone -- via the nuclear hormone receptor NHR-1. SSU-1-controlled signalling antagonizes insulin-like signalling and hence modulates insulin sensitivity. In short, we describe a previously unknown neurohormonal signalling pathway that is required specifically for some but not all consequences of reduced insulin-like signalling. In mammals, the nervous system plays a similarly important yet poorly understood role in modulating insulin sensitivity. Our results suggest that the mammalian nervous system might regulate insulin sensitivity via sulfotransferase-controlled neurohormonal signalling.
Project description:G4C2 repeat expansions within the C9orf72 gene are the most common genetic cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). The repeats undergo repeat-associated non-ATG translation to generate toxic dipeptide repeat proteins. Here, we show that insulin/Igf signalling is reduced in fly models of C9orf72 repeat expansion using RNA-sequencing of adult brain. We further demonstrate that activation of insulin/Igf signalling can mitigate multiple neurodegenerative phenotypes in flies expressing either expanded G4C2 repeats or the toxic dipeptide repeat protein poly-GR. Levels of poly-GR are reduced when components of the insulin/Igf signalling pathway are genetically activated in the diseased flies, suggesting a mechanism of rescue. Modulating insulin signalling in mammalian cells also lowers poly-GR levels. Remarkably, systemic injection of insulin improves the survival of flies expressing G4C2 repeats. Overall, our data suggest that modulation of insulin/Igf signalling could be an effective therapeutic approach against C9orf72 ALS/FTD.
Project description:Purpose. Insulin resistant muscle is resistant to gene expression changes induced by acute exercise. This study was undertaken to identify transcription factors that differentially respond to exercise in insulin resistance. Candidate transcription factors were identified from analysis of 5’-untranslated regions (5’-UTRs) of exercise responsive genes and from analysis of the 5’-UTRs of genes coding for proteins that differ in abundance in insulin resistance. Research design and methods. Muscle biopsies were obtained from lean and obese subjects before and after a single exercise bout. Euglycemic glucose clamps assessed insulin sensitivity. Global proteomics analysis identified differentially abundant proteins. The 5’-UTRs of genes coding for significant proteins were subjected to transcription factor enrichment analysis to identify candidate transcription factors. Q-rt-PCR to determine expression of candidate transcription factors was performed on RNA from resting and post-exercise muscle biopsies; immunoblots quantified protein abundance. Results. Obese subjects were insulin resistant compared to lean but performed exercise at the same intensity. Proteins involved in mitochondrial function, protein targeting and translation, and metabolism were among those significantly different between the groups. Transcription factor enrichment analysis of genes coding for these proteins revealed new candidate transcription factors. Q-rt-PCR analysis of RNA and immunoblot analysis from pre- and post-exercise muscle biopsies revealed several transcription and growth factors that had altered responses to exercise in insulin resistant subjects. Conclusions. These results confirm findings of an association between insulin sensitivity and transcription factor mRNA response to exercise and extend these results to show that obesity also may be a sufficient prerequisite for exercise resistance. Analysis of the muscle proteome together with determination of effects of exercise on expression of transcription factors suggests that abnormal responses of transcription factors to exercise may be responsible for differences in protein abundances in insulin resistant muscle.
Project description:Insulin signalling activity is well known to mediate transcriptional changes in response to nutrients and it is changed in the spargel mutant. We performed a genome-wide microarray study to investigate the role of Spargel as a transcriptional coregulator downstream of insulin receptor signalling.
Project description:Using mass spectrometry-based phosphoproteomics, we quantified 23,126 phosphosites in the skeletal muscle of five genetically distinct inbred mouse strains exposed to two controlled dietary environments, with and without acute insulin treatment. Almost half of the insulin-regulated phosphoproteome was altered by genetic background independently of diet, and high-fat high-sugar feeding also affected insulin signalling in a strain-dependent manner. Our data illuminated signalling network organisation principles, including the uncoupling of phosphosites targeted by the same kinase. Associating diverse signalling responses with insulin-stimulated glucose uptake uncovered regulators of muscle insulin responsiveness, including the regulatory phosphosite S469 on Pfkfb2, a key glycolytic enzyme.
Project description:Insulin signalling activity is well known to mediate transcriptional changes in response to nutrients and it is changed in the spargel mutant. We performed a genome-wide microarray study to investigate the role of Spargel as a transcriptional coregulator downstream of insulin receptor signalling. Experiment Overall Design: To investigate the effect of Spargel on transcriptional changes mediated by the insulin-signalling pathway we analyzed 12 samples in total: three biological replicates of the control with or without UAS-Inr (Inr_wt and ctrl_wt) and three biological replicates of the spargel mutant with or without UAS-Inr (Inr_KGand ctrl_KG).
Project description:Background: Despite the prevalence and biological relevance of both signalling pathways and alternative pre-mRNA splicing, our knowledge of how intracellular signalling impacts on alternative splicing regulation remains fragmentary. We report a genome-wide analysis of changes in alternative splicing using splicing-sensitive microarrays, induced by activation of two distinct signalling pathways, insulin and wingless, in Drosophila cells in culture. Results: Alternative splicing changes induced by insulin affect more than 150 genes and more than 50 genes are regulated by wingless activation. About 40% of the genes showing changes in alternative splicing also show regulation of mRNA levels, suggesting distinct but also significantly overlapping programs of transcriptional and posttranscriptional regulation. Distinct functional sets of genes are regulated by each pathway and, remarkably, a significant overlap is observed between functional categories of genes regulated transcriptionally and at the level of alternative splicing. Functions related with carbohydrate metabolism and cellular signalling are enriched among genes regulated by insulin and wingless, respectively. Computational searches identify pathway-specific sequence motifs enriched near regulated 5â splice sites. Conclusion: Taken together, our data indicate that signalling cascades trigger pathway-specific and biologically coherent regulatory programs of alternative splicing regulation. They also reveal that alternative splicing can provide a novel molecular mechanism for cross-talk between different signalling pathways. To monitor transcriptional and alternative splicing changes induced by activation of the insulin and wingless pathways, a custom-designed microarray platform was employed featuring probes for all Drosophila genes for which different mRNA isoforms generated by alternative splicing have been described (see Blanchette M, Green RE, Brenner SE, Rio DC: Global analysis of positive and negative pre-mRNA splicing regulators in Drosophila. Genes Dev 2005, 19(11):1306-1314.). Three biological replicates of total RNA isolated after pathway activation or controls (untreated cells for insulin, control dsRNA for wingless) were purified, reverse transcribed into cDNA and labelled with Cy5 or Cy3 fluorochromes and the cDNA was hybridized to the microarray,
Project description:1. evaluation of diagnostic importance of insulin like growth factor binding protein3 in patient with recently diagnosed as Colorectal cancer
2. correlation between the diagnostic efficacy of insulin like growth factor binding protein 3 with routine marker carcinoembryonic antigen.