Uncoupling Insulin Sensitivity From Longevity: A Sex-Dependent Effect of Hepatic Glucagon Signaling
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ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE302496 | GEO | 2026/01/05
REPOSITORIES: GEO
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Project description:Oscillations between lipid anabolism and catabolism allow for long-term preservation of cellular health amid systemic metabolic fluctuations. As a conserved aging determinant, fasting can improve disease outcomes and extend lifespan. Yet, the relative importance of activating lipid catabolism versus its attenuation in fasting-induced longevity remains unclear. The robust adaptability of the soil-dwelling worms, C. elegans, to variable nutrient availability provides an excellent means to better understand how metabolic transitions alter aging trajectories. Here, we show that, rather than activation, the silencing of lipid catabolism upon nutrient replenishment is essential for lifespan extension through fasting. The fasting-responsive nuclear hormone receptor, NHR-49, is pivotal in activating lipid catabolism through β-oxidation. Unlike traditional ligand-regulated nuclear hormone receptors, NHR-49 employs a unique regulatory mechanism that bypasses ligand binding, instead relying on cofactors to mediate its transcriptional attenuation and turnover during times of nutrient stress. Here, we identify casein kinase 1 alpha 1 (KIN-19) as a central regulator of metabolic plasticity and fasting-induced longevity, which attenuates β-oxidation via primed phosphorylation of NHR-49. Overall, cooperative, ligand-independent silencing of this conserved nuclear hormone receptor promotes longevity associated with fasting.
2025-12-19 | GSE314580 | GEO
Project description:Oscillations between lipid anabolism and catabolism allow for long-term preservation of cellular health amid systemic metabolic fluctuations. As a conserved aging determinant, fasting can improve disease outcomes and extend lifespan. Yet, the relative importance of activating lipid catabolism versus its attenuation in fasting-induced longevity remains unclear. The robust adaptability of the soil-dwelling worms, C. elegans, to variable nutrient availability provides an excellent means to better understand how metabolic transitions alter aging trajectories. Here, we show that, rather than activation, the silencing of lipid catabolism upon nutrient replenishment is essential for lifespan extension through fasting. The fasting-responsive nuclear hormone receptor, NHR-49, is pivotal in activating lipid catabolism through β-oxidation. Unlike traditional ligand-regulated nuclear hormone receptors, NHR-49 employs a unique regulatory mechanism that bypasses ligand binding, instead relying on cofactors to mediate its transcriptional attenuation and turnover during times of nutrient stress. Here, we identify casein kinase 1 alpha 1 (KIN-19) as a central regulator of metabolic plasticity and fasting-induced longevity, which attenuates β-oxidation via primed phosphorylation of NHR-49. Overall, cooperative, ligand-independent silencing of this conserved nuclear hormone receptor promotes longevity associated with fasting.
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Project description:Cholesterol has attracted significant attention as a possible lifespan regulator. It has been reported that serum cholesterol levels have an impact on mortality due to age-related disorders such as cardiovascular disease. Diet is also known to be an important lifespan regulator. Dietary restriction retards the onset of age-related diseases and extends lifespan in various organisms. Although cholesterol and dietary restriction are known to be lifespan regulators, it remains to be established whether cholesterol is involved in dietary restriction-induced longevity. Here, we show that cholesterol deprivation suppresses longevity induced by intermittent fasting, which is one of the dietary restriction regimens that effectively extend lifespan. We also found that cholesterol is required for the fasting-induced upregulation of transcriptional target genes such as the insulin/IGF-1 pathway effector DAF-16 and that cholesterol deprivation suppresses the long lifespan of the insulin/IGF-1 receptor daf-2 mutant. Remarkably, we found that cholesterol plays an important role in the fasting-induced nuclear accumulation of DAF-16. Moreover, knockdown of the cholesterol-binding protein NSBP-1, which has been shown to bind to DAF-16 in a cholesterol-dependent manner and to regulate DAF-16 activity, suppresses both fasting-induced longevity and DAF-16 nuclear accumulation. Furthermore, this suppression was not additive to the cholesterol deprivation-induced suppression, which suggests that NSBP-1 mediates, at least in part, the action of cholesterol to promote fasting-induced longevity and DAF-16 nuclear accumulation. These findings identify a novel role for cholesterol in the regulation of lifespan. Two independent replicates were performed. Total RNA was extracted with TRIzol (Invitrogen). The extracted RNA was purified with PureLink RNA Micro Kit (Invitrogen) and analyzed with Agilent 2100 Bioanalyzer to assess the RNA integrity. The microarray procedures were performed according to Affymetrix protocols. Hybridized arrays were scanned using an Affymetrix GeneChip Scanner.
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Project description:We assessed the change in hepatic transciptional pattern after treatment with SGLT-2 inhibitors canagliflozin in a mice model of diet-induced obesity. Pharmacologic inhibition of the renal sodium/glucose cotransporter-2 induces glycosuria and reduces glycemia. Given that SGLT2 inhibitors (SGLT2i) reduce mortality and CV risk in T2D, improved understanding of molecular mechanisms mediating these metabolic effects is required. Treatment of obese but nondiabetic mice with the SGLT2i canagliflozin (CANA) reduces adiposity, improves glucose tolerance despite reduced plasma insulin, increases plasma ketones, and improves plasma lipid profiles. We utilized an integrated transcriptomic-metabolomics approach to demonstrate that CANA modulates key nutrient-sensing pathways, with activation of AMPK and inhibition of mTOR, independent of insulin or glucagon sensitivity or signaling. Moreover, CANA induces transcriptional reprogramming to activate catabolic pathways, increase fatty acid oxidation, reduce hepatic steatosis and diacylglycerol content, and increase hepatic and plasma levels of FGF21. Taken together, these data demonstrate that SGLT-2 inhibition triggers a fasting-like transcriptional and metabolic paradigm.
2020-04-16 | GSE148702 | GEO
Project description:Dietary restriction (DR) is the most effective and reproducible intervention to extend lifespan in divergent species1. In mammals, two regimens of DR, intermittent fasting (IF) and caloric restriction (CR), have proven to extend lifespan and reduce the incidence of age-related disorders2. An important characteristic of IF is that it can increase lifespan, even when there is little or no overall decrease in calorie intake2. The molecular mechanisms underlying IF-induced longevity, however, remain largely unknown. Here we establish an IF regimen that effectively extends the lifespan of Caenorhabditis elegans, and show that a nutrient-related signalling molecule, the low molecular weight GTPase Cel-Rheb, has a dual role in lifespan regulation; Cel-Rheb is required for the IF-induced longevity, whereas inhibition of Cel-Rheb mimics the CR effects. We also show that Cel-Rheb exerts its effects in part via the insulin/IGF-like signalling effector DAF-16 in IF, and that Cel-Rheb is required for fasting-induced nuclear translocation of DAF-16. We find that HSP-12.6, a DAF-16 target, functions to mediate the IF-induced longevity. Furthermore, our analyses demonstrate that most of fasting-induced upregulated genes require Cel-Rheb function for their induction, and that Cel-Rheb/Cel-TOR signalling is required for the fasting-induced downregulation of an insulin-like peptide, INS-7. These findings identify the essential role of signalling via Cel-Rheb in IF-induced longevity and gene expression changes, and suggest a molecular link between the IF-induced longevity and the insulin/IGF-like signalling pathway.
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2017-05-01 | GSE51046 | GEO
Project description:Diabetic kidney disease (DKD) is the leading cause of end-stage kidney disease (ESKD), and few treatment options are available today to prevent the progressive loss of renal function. Tubular abnormalities may precede glomerular pathology early and indicate the functional progression of DKD, however, pathological mechanisms that initiate tubular abnormalities are poorly understood. Here, we found that glucagon receptor (Gcgr) is specifically and highly expressed in proximal tubular cells (PTEC) of kidney. Glucagon injection exacerbated lipid accumulation, glycogen content, inflammation, fibrosis, and renal injury, along with morphology changes on proximal tubules, podocytes, glomerular basement membrane (GBM), and mitochondria in the early phase of DKD mice. Whereas, the specific knockdown or knockout of Gcgr in PTEC of kidney almost completely halted the development of DKD. In contrary to the effect of short-term glucagon stimulation on fatty acid oxidation, long-term glucagon exposure led to glucagon reversal in PTEC, which is characterized by reduced energy production and promoted lipogenesis, and this effect was through the Gcgr-PKA-Creb-mTOR pathway. Accordingly, anti-GCGR antibody treatment greatly blocked the pathogenesis of DKD induced by both type 2 and type 1 diabetes. Thus, our results revealed a novel role of glucagon/GCGR signaling in PTEC lipogenesis and DKD, and Gcgr would be a promising therapeutic drug target for the treatment of DKD.
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