Project description:Dietary habits and obesity in fathers imprint upon progeny through epigenetic signals carried by sperm RNA. By activating hypothalamic AgRP neurons in mice to mimic obesity's effects, we observed significant alterations in sperm tsRNAs, miRNAs, and rsRNAs. These changes, particularly in tsRNAs, mirror those seen with short-term high-fat diets, suggesting a shared upstream regulatory mechanism involving AgRP neurons that influence metabolic epigenetic inheritance.
Project description:Hypothalamic neurons expressing Agouti-related peptide (AgRP) are critical for initiating food intake, but druggable biochemical pathways that control this response remain elusive. Thus, genetic ablation of insulin or leptin signaling in AgRP neurons is predicted to reduce satiety but fails to do so. FoxO1 is a shared mediator of both pathways, and its inhibition is required to induce satiety. Accordingly, FoxO1 ablation in AgRP neurons of mice results in reduced food intake, leanness, improved glucose homeostasis, and increased sensitivity to insulin and leptin. Expression profiling of flow-sorted FoxO1-deficient AgRP neurons identifies G-protein-coupled receptor Gpr17 as a FoxO1 target whose expression is regulated by nutritional status. Intracerebroventricular injection of Gpr17 agonists induces food intake, whereas Gpr17 antagonist cangrelor curtails it. These effects are absent in Agrp-Foxo1 knockouts, suggesting that pharmacological modulation of this pathway has therapeutic potential to treat obesity. We used microarrays to detail the change of gene expression in AgRP neurons after knocking out FoxO1. AgRP neurons from control and KO mice were collected by FACS. Gene expression was analyzed by microarray.
Project description:Autophagy represents a key regulator of aging and metabolism upon cell autonomous sensing of energy deprivation. We find that fasting in mice activates autophagy in liver paralleled by activation of hypothalamic AgRP neurons. Optogenetic and chemogenetic activation of AgRP neurons induces autophagy, alters phosphorylation of autophagy regulators and promotes ß-oxidation in the liver. AgRP neuron dependent induction of liver autophagy relies on NPY expression in these neurons. AgRP neuron projections in the paraventricular nucleus of the hypothalamus (PVH) and the lateral hypothalamus (LHA) mediate AgRP neuron-dependent control of liver autophagy. Conversely, inhibiting AgRP neurons during energy deprivation abrogates induction of hepatic autophagy and re-wiring of metabolism. Finally, AgRP neuron activation increases circulating corticosterone concentrations, and reduction of hepatic glucocorticoid receptor expression attenuates AgRP neuron-dependent activation of hepatic autophagy. Collectively, our study reveals a fundamental regulatory principle of non-cell autonomous control of liver autophagy in control of metabolic adaptation during nutrient deprivation.
Project description:We have found that acute activation of AgRP-neurons lead to inhibition of insulin-stimulated glucose uptake into BAT. Based on this finding, we asked whether this effect was accompanied by acute changes in gene expression, which could point to the mechanism(s) underlying the impaired insulin sensitivity. In summary, our data suggest that activation of AgRP-neurons actuely reprograms gene expression in BAT towards a myogenic profile. The arcuate nucleus of 4 mice expressing channelrhodopsin 2 in AgRP-neurons through Cre-mediated recombination (ChR2-AgRP) and 4 Cre-negative controls (ChR2-fl/WT, Ctrl), were stimulated with blue laser light for one hour, total RNA from BAT was isolated and subjected to a microarray-based gene expression analysis.
Project description:Hypothalamic neurons expressing Agouti-related peptide (AgRP) are critical for initiating food intake, but druggable biochemical pathways that control this response remain elusive. Thus, genetic ablation of insulin or leptin signaling in AgRP neurons is predicted to reduce satiety but fails to do so. FoxO1 is a shared mediator of both pathways, and its inhibition is required to induce satiety. Accordingly, FoxO1 ablation in AgRP neurons of mice results in reduced food intake, leanness, improved glucose homeostasis, and increased sensitivity to insulin and leptin. Expression profiling of flow-sorted FoxO1-deficient AgRP neurons identifies G-protein-coupled receptor Gpr17 as a FoxO1 target whose expression is regulated by nutritional status. Intracerebroventricular injection of Gpr17 agonists induces food intake, whereas Gpr17 antagonist cangrelor curtails it. These effects are absent in Agrp-Foxo1 knockouts, suggesting that pharmacological modulation of this pathway has therapeutic potential to treat obesity. We used microarrays to detail the change of gene expression in AgRP neurons after knocking out FoxO1.
Project description:Agouti-related peptide (AgRP)- and proopiomelanocortin (POMC)-expressing neurons reciprocally regulate food intake. Here, we combined non-interacting recombinases to simultaneously express functionally opposing chemogenetic receptors in AgRP and POMC neurons allowing to compare metabolic responses in mice with simultaneous activation of AgRP and inhibition of POMC neurons with isolated activation of AgRP neurons or isolated inhibition of POMC neurons. These experiments revealed that food intake is regulated by the additive effect of AgRP-neuron activation and POMC-neuron inhibition, while systemic insulin sensitivity and gluconeogenesis are differentially modulated by isolated versus simultaneous regulation of AgRP and POMC neurons. We identified a neurocircuit engaging Npy1R-expressing neurons in the paraventricular nucleus of the hypothalamus (PVH), where activated AgRP- and inhibited POMC neurons synergize to promote food consumption and activate neurons in the nucleus tractus solitarii (NTS). We then performed single-nuclei RNA sequencing to define the molecular nature of Fos+ cells in the posterior NTS/AP area that respond to simultaneous chemogenetic intervention over AgRP and POMC neurons and identified TH+ neurons as candidates for receiving neuronal inputs initiated by the simultaneous and coordinated interplay between AgRP and POMC neurocircuits and relayed to the NTS area by the silenced glutamatergic Npy1R neurons.
Project description:miRNA-33a/b provides a critical link between the regulation of cholesterol and fatty acid biosynthesis by SREBPs, and cholesterol efflux, high-density lipoprotein (HDL) biogenesis and fatty acid oxidation pathways. Notably, pharmacological inhibition of miR-33 elevates hepatic ABCA1 expression, thereby increasing circulating HDL-C and attenuating the progression of atherosclerosis, highlighting the therapeutic potential of miR-33 inhibitors for the treatment of cardiovascular disease. However, work with genetic models of miR-33 deficiency has clearly demonstrated that global loss of miR-33 promotes the development of obesity and metabolic dysfunction. We sought to determine if miR-33 is directly involved in regulating the activity of the AgRP and POMC neurons that promote signals of hunger and satiety, respectively. We have generated AgRP conditional KO mouse to analyze the effect of removing miR-33 in these neurons. After miR-33 removal, mice were fed a HFD and then the expression of different markers related to activiation or inhibition of AgRP neurons was analyzed by scRNAseq.
Project description:The arcuate nucleus of the hypothalamus (ARH) is one key structure controlling energy homeostasis. While it has been shown that the biogenic amines dopamine and serotonin modulate food intake controlling NPY/AgRP and/or POMC neurons in the ARH, the neural substrates that mediate the effect of noradrenaline (NA) on energy homeostasis remain elusive. By electrophysiological recordings and cell type-specific transcriptomics we show that the main neuronal populations in the ARH, NPY/AgRP and POMC neurons express a combination of excitatory and inhibitory adrenergic receptors (ARs). Surprisingly, NA had a clear differential effect on these neurons. Activation of NPY/AgRP neurons is mediated by _1A - and _- ARs, while POMC neurons are inhibited via _2A ARs. Collectively, our data indicate an orexigenic influence of NA on the ARH circuitry that controls energy balance
Project description:Knock out of Dnmt3a in AgRP neurons leads to a sedentary, adiposity-prone adult phenotype associated with widespread changes in DNA methylation and gene expression.
Project description:Here, we revealed that optogenetic activation of AgRP neurons alters liver transcriptome associated with autophagy, glucose metabolism, lipid metabolism and ß-oxidation.