The response of the hypothalamus to leptin and a high-fat diet in mice
Ontology highlight
ABSTRACT: Energy homeostasis is regulated by the hypothalamus but fails when animals are fed a high-fat diet (HFD), and leptin insensitivity and obesity develops. We have used a microarray-based transcriptomics approach to identify novel genes regulated by HFD and leptin in the hypothalamus using mouse global arrays.
Project description:Genome wide association studies (GWAS) in obesity have identified a large number of noncoding loci located near genes expressed in the central nervous system. However, due to the difficulties in isolating and characterizing specific neuronal subpopulations, very few obesity-associated SNPs have been functionally characterized. Leptin responsive neurons in the hypothalamus are essential in controlling energy homeostasis and body weight. Here, we show that by combining FACS-sorting of leptin-responsive hypothalamic neuron nuclei with genomic approaches (RNA-seq, ChIP-seq, ATAC-seq), we can provide a comprehensive map of leptin-response specific regulatory elements, several of which overlap obesity-associated GWAS variants. Further demonstrating the robustness of our leptin-response neuron regulome, we functionally characterize a novel enhancer near Socs3, a leptin response-associated transcription factor. Combined, our results provide a comprehensive map of active genomic regions in leptin-responsive neurons and present a blueprint for functionally characterizing obesity-associated SNPs in the hypothalamus.
Project description:Central leptin action is sufficient to restore euglycemia in type 1 diabetes via an insulin-independent manner. To examine the mechanism in the hypothalamus at the transcription level, numerous genes that showed expression changes to STZ-induced type 1 diabetes and were reversed by central leptin action were identified.
Project description:To further identify the mostly influenced signal pathways under Kdm6 inhibitor treatment, the microarray analysis was performed to screen the gene expression profile in the hypothalamus of DIO mice. The DIO mice were administrated with vehicle or 30 mg/kg GSK-J4 i.p. for 4 days. Totally, 205 genes were up regulated over 2 fold and 845 genes were down regulated over 2 fold.
Project description:Leptin binding to the leptin receptor (LepR) causes rapid signaling to the nucleus. We investigated the early (2 hr) transcriptional response to acute leptin injectio (intracerebroventricular) in the preoptic area/hypothalamus/pituitary of juvenile Xenopus laevis frogs. Frogs were given i.c.v. injections of 0.6% saline or recombinant X. laevis leptin (rxLeptin; 20 ng/g BW) and 2 hrs later killed and the preoptic area/hypothalamus/pituitary dissected.
Project description:Leptin-responsive genes in the pathway of a leptin signal from the hypothalamus to the liver has not been detected. We used microarray to detailed the expression of gene in liver in the status of leptin deficiency, and leptin administration. As leptin deficient status, we use Lepmkyo/Lepmkyo rats or Lepob/Lepob mice and their wild type littermates.
Project description:The relationship between loss of hypothalamic function and onset of diabetes mellitus remains elusive. Therefore, we generated a targeted oxidative-stress murine model utilizing conditional knockout of selenocysteine-tRNA (Trsp) using rat insulin promoter-driven-Cre (RIP-Cre). These Trsp-knockout (TrspRIPKO) mice exhibit deletion of Trsp in both hypothalamic cells and pancreatic β-cells leading to increased hypothalamic oxidative stress and severe insulin resistance. Leptin signals were suppressed and numbers of proopiomelanocortin-positive neurons in the hypothalamus were decreased. In contrast, a Trsp-knockout mouse (TrspIns1KO) expressing Cre specifically in pancreatic β-cells, but not in the hypothalamus, did not display insulin and leptin resistance, demonstrating a critical role of the hypothalamus in the onset of diabetes mellitus. Nrf2 (NF-E2-related-factor-2) regulates antioxidant gene expression. Gene-driven increase in Nrf2 signaling suppressed hypothalamic oxidative stress and improved insulin and leptin resistance in TrspRIPKO mice. Thus, Nrf2 harbors the potential to prevent the onset of diabetic mellitus by reducing hypothalamic oxidative damage.
Project description:The relationship between loss of hypothalamic function and onset of diabetes mellitus remains elusive. Therefore, we generated a targeted oxidative-stress murine model utilizing conditional knockout of selenocysteine-tRNA (Trsp) using rat insulin promoter-driven-Cre (RIP-Cre). These Trsp-knockout (TrspRIPKO) mice exhibit deletion of Trsp in both hypothalamic cells and pancreatic β-cells leading to increased hypothalamic oxidative stress and severe insulin resistance. Leptin signals were suppressed and numbers of proopiomelanocortin-positive neurons in the hypothalamus were decreased. In contrast, a Trsp-knockout mouse (TrspIns1KO) expressing Cre specifically in pancreatic β-cells, but not in the hypothalamus, did not display insulin and leptin resistance, demonstrating a critical role of the hypothalamus in the onset of diabetes mellitus. Nrf2 (NF-E2-related-factor-2) regulates antioxidant gene expression. Gene-driven increase in Nrf2 signaling suppressed hypothalamic oxidative stress and improved insulin and leptin resistance in TrspRIPKO mice. Thus, Nrf2 harbors the potential to prevent the onset of diabetic mellitus by reducing hypothalamic oxidative damage.
Project description:The neurons of the melanocortin system regulate feeding and energy homeostasis through a combination of electrical and endocrine mechanisms. However, the molecular basis for this functional heterogeneity are poorly understood. Here, a voltage-gated potassium (K+) channel named KCNB1 (alias Kv2.1), formed stable complexes with the leptin receptor (LepR) in proopiomelanocortin (POMC) expressing neurons of the Arcuate nucleus of the hypothalamus (ARCPOMC). Mice lacking functional KCNB1 channels (NULL mice), exhibited constitutive depolarization of ARCPOMC neurons along with aberrant POMC production. In NULL neurons, canonical LepR-STAT3 signaling--which underlies POMC production--was impaired, whereas non-canonical insulin receptor substrate PI3K/Akt/FOXO1 and ERK signaling were significantly upregulated. Accordingly, the NULL animals were insensitive to anorexic stimuli induced by leptin administration and produced less adipose tissue and circulating leptin than WT animals. Taken together, these findings unveil an exquisite mechanism of metabolic regulation whereby synergistic control of neuronal excitability and endocrine function is achieved through the partnership between a K+ channel and a hormone receptor. As aberrant KCNB1 channels cause developmental and epileptic encephalopathies, these results further establish a K+ channel as a causative link between epileptic and metabolic disorders.