Insulin and IGF-1 elicit robust transcriptional regulation to modulate autophagy in astrocytes
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ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE213062 | GEO | 2022/10/31
REPOSITORIES: GEO
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Project description:ObjectiveInsulin is a principal metabolic hormone. It regulates a plethora of metabolic pathways in peripheral tissues. The highly homologous insulin-like growth factor 1 (IGF-1), on the other hand, is important for development and growth. Recent studies have shown that insulin and IGF-1 signaling plays fundamental roles in the brain. Loss of insulin or IGF-1 receptors in astrocytes leads to altered glucose handling, mitochondrial metabolism, neurovascular coupling, and behavioral abnormalities in mice. Here, we aim to investigate molecular mechanisms by which insulin and IGF-1 signaling regulates astrocyte functions.MethodsIR-flox and IRKO primary astrocytes were treated with 100 nM insulin or IGF-1 for 6 h, and their transcriptomes were analyzed. Astrocytes with either IR deletion, IGF1R deletion or both were used to examine receptor-dependent transcriptional regulations using qPCR. Additional immunoblotting and confocal imaging studies were performed to functionally validate pathways involved in protein homeostasis.ResultsUsing next-generation RNA sequencing, we show that insulin significantly regulates the expression of over 1,200 genes involved in multiple functional processes in primary astrocytes. Insulin-like growth factor 1 (IGF-1) triggers a similar robust transcriptional regulation in astrocytes. Thus, over 50% of the differentially expressed genes are regulated by both ligands. As expected, these commonly regulated genes are highly enriched in pathways involved in lipid and cholesterol biosynthesis. Additionally, insulin and IGF-1 induce the expression of genes involved in ribosomal biogenesis, while suppressing the expression of genes involved in autophagy, indicating a common role of insulin and IGF-1 on protein homeostasis in astrocytes. Insulin-dependent suppression of autophagy genes, including p62, Ulk1/2, and several Atg genes, is blunted only when both IR and IGF1R are deleted.ConclusionsIn summary, insulin and IGF-1 potently suppress autophagy in astrocytes through transcriptional regulation. Both IR and IGF1R can elicit ligand-dependent transcriptional suppression of autophagy. These results demonstrate an important role of astrocytic insulin/IGF-1 signaling on proteostasis. Impairment of this regulation in insulin resistance and diabetes may contribute to neurological complications related to diabetes.
| S-EPMC9731889 | biostudies-literature
Project description:Insulin and IGF-1 elicit robust transcriptional regulation to modulate autophagy in astrocytes
| PRJNA878847 | ENA
Project description:Exposure to adverse nutritional and metabolic environments during critical periods of development can exert long-lasting effects on health outcomes of an individual and its descendants. Although such metabolic programming has been observed in multiple species and in response to distinct nutritional stressors, conclusive insights into signaling pathways and mechanisms responsible for initiating, mediating and manifesting changes to metabolism and behavior across generations remain scarce. By employing a multigenerational starvation paradigm in C. elegans, we show that starvation-induced changes in DAF-16/FoxO activity, the main downstream target of insulin/IGF-1 receptor signaling, are responsible for metabolic programming phenotypes. Tissue-specific depletion of DAF-16/FoxO during distinct developmental time points further demonstrates that DAF-16/FoxO acts in somatic tissues, but not directly in the germline, to both initiate and manifest metabolic programming. In conclusion, our study deciphers multifaceted and critical roles of highly conserved insulin/IGF-1 receptor signaling in determining health outcomes and behavior across generations.
2023-03-09 | GSE198939 | GEO
Project description:Inhibition of the insulin/insulin-like growth factor signalling pathway increases lifespan and protects against neurodegeneration in model organisms, and has been considered as a potential therapeutic target. This pathway is upstream of mTORC1, a negative regulator of autophagy. Thus, we expected autophagy to be activated by insulin-like growth factor-1 (IGF-1) inhibition, which could account for many of its beneficial effects. Paradoxically, we found that IGF-1 inhibition attenuates autophagosome formation. The reduced amount of autophagosomes present in IGF-1R depleted cells can be, at least in part, explained by a reduced formation of autophagosomal precursors at the plasma membrane. In particular, IGF-1R depletion inhibits mTORC2, which, in turn, reduces the activity of protein kinase C (PKC?/?). This perturbs the actin cytoskeleton dynamics and decreases the rate of clathrin-dependent endocytosis, which impacts autophagosome precursor formation. Finally, with important implications for human diseases, we demonstrate that pharmacological inhibition of the IGF-1R signalling cascade reduces autophagy also in zebrafish and mice models. The novel link we describe here has important consequences for the interpretation of genetic experiments in mammalian systems and for evaluating the potential of targeting the IGF-1R receptor or modulating its signalling through the downstream pathway for therapeutic purposes under clinically relevant conditions, such as neurodegenerative diseases, where autophagy stimulation is considered beneficial.
| S-EPMC3889807 | biostudies-other
Project description:While neurons principally mediate brain function, astrocytes are emerging as cells with important neuromodulatory actions in brain physiology. In addition to homeostatic roles, astrocytes respond to neurotransmitters with calcium transients stimulating the release of gliotransmitters that regulate synaptic and neuronal functions. We investigated astrocyte-neuronal network interactions in vivo by combining two-photon microscopy to monitor astrocyte calcium and electrocorticogram to record neuronal network activity in the somatosensory cortex during sensory stimulation. We found astrocytes respond to sensory stimuli in a stimulus-dependent manner. Sensory stimuli elicit a surge of neuronal network activity in the gamma range (30-50?Hz) followed by a delayed astrocyte activity that dampens the steady-state gamma activity. This sensory-evoked gamma activity increase is enhanced in transgenic mice with impaired astrocyte calcium signaling and is decreased by pharmacogenetic stimulation of astrocytes. Therefore, cortical astrocytes respond to sensory inputs and regulate sensory-evoked neuronal network activity maximizing its dynamic range.
| S-EPMC7378834 | biostudies-literature
Project description:Intermittent fasting (IF) is a dietary regimen aimed to restrict energy intake via alternate periods of ad libitum food consumption and fasting, without compromise of nutritional composition intake. Prophylactic IF have been well-established in many animal studies to promote longevity as well as ameliorate the development and manifestation of age-related diseases such as cardiovascular, neurodegenerative as well as metabolic diseases. However, while vast experimental evidences have pointed out that IF is able to exert plethora effects against these diseases, understanding with regards to the underlying mechanisms remain in their infancy. Recently, an emerging area of research in the field of epigenetics have been shown to be a cornerstone in mediating the interaction between environmental factors and genome status. IF is a lifestyle intervention that may serves as potential environmental influences over the epigenome status of individuals. However, there is no current information available that shows that IF can induce epigenetic changes. Here, we show that IF is able to influence the modulation of histone H3 lysine 9 trimethylation (H3K9me3) epigenetic mark in C57/BL6 male mice cerebellum, which in turn helps to control a plethora of transcriptomic changes involved in robust metabolic switching processes commonly observed during IF. Interestingly, both epigenomic and transcriptomic modulation are still observed following a refeeding regimen, which may suggest the possibility of epigenetic maintenance induced by IF at this epigenetic locus. However, we found a loss of H3K9me3 maintenance of transcriptomic changes after abolishment of IF. Collectively, our study helps to characterize a novel mechanism of IF in the epigenetic-transcriptomic axis, which control a myriad of metabolic process changes that provide better understanding of IF-induced effects.
2019-08-19 | GSE135945 | GEO
Project description:Oxygen is vital for the development and survival of mammals. In response to hypoxia, the brain initiates numerous adaptive responses at the organ level as well as at the molecular and cellular levels, including the alteration of gene expression. Astrocytes play critical roles in the proper functioning of the brain; thus the manner in which astrocytes respond to hypoxia is likely important in determining the outcome of brain hypoxia. Here, we used microarray gene expression profiling and data-analysis algorithms to identify and analyze hypoxia-responsive genes in primary human astrocytes. We also compared gene expression patterns in astrocytes with those in human HeLa cells and pulmonary artery endothelial cells (ECs). Remarkably, in astrocytes, five times as many genes were induced as suppressed, whereas in HeLa and pulmonary ECs, as many as or more genes were suppressed than induced. More genes encoding hypoxia-inducible functions, such as glycolytic enzymes and angiogenic growth factors, were strongly induced in astrocytes compared with HeLa cells. Furthermore, gene ontology and computational algorithms revealed that many target genes of the EGF and insulin signaling pathways and the transcriptional regulators Myc, Jun, and p53 were selectively altered by hypoxia in astrocytes. Indeed, Western blot analysis confirmed that two major signal transducers mediating insulin and EGF action, Akt and MEK1/2, were activated by hypoxia in astrocytes. These results provide a global view of the signaling and regulatory network mediating oxygen regulation in human astrocytes.. This SuperSeries is composed of the following subset Series:; GSE3045: Astrocytic response to hypoxia; GSE3051: HeLa response to hypoxia Experiment
2007-10-26 | E-GEOD-4483 | biostudies-arrayexpress
Project description:Starvation-induced changes in somatic Insulin/IGF-1R signaling drive metabolic programming across generations
| PRJNA817543 | ENA
Project description:Despite a high degree of homology, insulin and IGF-1 receptors (IR/IGF1R) mediate distinct cellular and physiological functions. Here, using chimeric and site-mutated receptors, we demonstrate how domain differences between IR and IGF1R contribute the distinct functions of these receptors. Receptors with the intracellular domain of IGF1R show increased activation of Shc and Gab-1 and more potent regulation of genes involved in proliferation, corresponding to its higher mitogenic activity. Conversely, receptors with the intracellular domain of IR display higher IRS-1 phosphorylation, stronger regulation of genes in metabolic pathways and more dramatic glycolytic responses to hormonal stimulation. We generated mouse brown preadipocytes in which both insulin and IGF-1 receptors (IR and IGF1R) had been genetically inactivated using Cre-lox recombination. These IR and IGF1R DKO cells were then reconstituted with wild-type mouse IR, IGF1R, or one of two chimeric receptors: IR/IGF1R with the IR extracellular domain (ECD) fused to the IGF1R transmembrane and intracellular domains (ICD) and IGF1R/IR with the ECD of IGF1R fused to the ICD domains of IR. Three independent clones for each line were used for the study. For expression analysis, we serum-starved the preadipocytes clones overnight and stimulated cells with 100 nM insulin, IGF-1 or vehicle for 6 h, and subjected the cellular RNA to analysis using Affymetrix Mouse Gene 2.0 ST arrays.
2016-07-01 | E-GEOD-81921 | biostudies-arrayexpress
Project description:Analysis of newborn mouse epidermis lacking the expression of Insulin receptor (IR) and Insulin like growth factor 1 receptor (IGF-1R). Results show that IR/IGF-1R signalling control epidermal morphogenesis.
2013-05-18 | GSE47065 | GEO