Sirt3 in POMC neurons controls energy balance in a sex- and diet-dependent manner.
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ABSTRACT:
SUBMITTER: Quinones M
PROVIDER: S-EPMC8005845 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:BackgroundOrphanin FQ (aka nociceptin; N/OFQ) binds to its nociceptin opioid peptide (NOP) receptor expressed in proopiomelanocortin (POMC) neurons within the arcuate nucleus (ARC), a critical anorexigenic component of the hypothalamic energy balance circuitry. It inhibits POMC neurons by modifying neuronal excitability both pre- and postsynaptically. We tested the hypothesis that N/OFQ inhibits neurotransmission at synapses involving steroidogenic factor (SF)-1 neurons in the ventromedial nucleus (VMN) and ARC POMC neurons in a sex- and diet-dependent fashion.MethodsElectrophysiological recordings were done in intact male and in cycling and ovariectomized female NR5A1-Cre and eGFP-POMC mice. Energy homeostasis was assessed in wildtype animals following intra-ARC injections of N/OFQ or its saline vehicle.ResultsN/OFQ (1??M) decreased light-evoked excitatory postsynaptic current (leEPSC) amplitude more so in males than in diestrus or proestrus females, which was further accentuated in high-fat diet (HFD)-fed males. N/OFQ elicited a more robust outward current and increase in conductance in males than in diestrus, proestrus, and estrus females. These pleiotropic actions of N/OFQ were abrogated by the NOP receptor antagonist BAN ORL-24 (10??M). In ovariectomized female eGFP-POMC mice, 17?-estradiol (E2; 100?nM) attenuated the N/OFQ-induced postsynaptic response. SF-1 neurons from NR5A1-Cre mice also displayed a robust N/OFQ-induced outward current and increase in conductance that was sexually differentiated and suppressed by E2. Finally, intra-ARC injections of N/OFQ increased energy intake and decreased energy expenditure, which was further potentiated by exposure to HFD and diminished by estradiol benzoate (20??g/kg; s.c.).ConclusionThese findings show that males are more responsive to the pleiotropic actions of N/OFQ at anorexigenic VMN SF-1/ARC POMC synapses, and this responsiveness can be further enhanced under conditions of diet-induced obesity/insulin resistance.
| S-EPMC6373052 | biostudies-literature
Project description:Protein tyrosine phosphatase 1B (PTP1B) and SH2 domain-containing protein tyrosine phosphatase-2 (SHP2) have been shown in mice to regulate metabolism via the central nervous system, but the specific neurons mediating these effects are unknown. Here, we have shown that proopiomelanocortin (POMC) neuron-specific deficiency in PTP1B or SHP2 in mice results in reciprocal effects on weight gain, adiposity, and energy balance induced by high-fat diet. Mice with POMC neuron-specific deletion of the gene encoding PTP1B (referred to herein as POMC-Ptp1b-/- mice) had reduced adiposity, improved leptin sensitivity, and increased energy expenditure compared with wild-type mice, whereas mice with POMC neuron-specific deletion of the gene encoding SHP2 (referred to herein as POMC-Shp2-/- mice) had elevated adiposity, decreased leptin sensitivity, and reduced energy expenditure. POMC-Ptp1b-/- mice showed substantially improved glucose homeostasis on a high-fat diet, and hyperinsulinemic-euglycemic clamp studies revealed that insulin sensitivity in these mice was improved on a standard chow diet in the absence of any weight difference. In contrast, POMC-Shp2-/- mice displayed impaired glucose tolerance only secondary to their increased weight gain. Interestingly, hypothalamic Pomc mRNA and alpha-melanocyte-stimulating hormone (alphaMSH) peptide levels were markedly reduced in POMC-Shp2-/- mice. These studies implicate PTP1B and SHP2 as important components of POMC neuron regulation of energy balance and point to what we believe to be a novel role for SHP2 in the normal function of the melanocortin system.
| S-EPMC2827947 | biostudies-literature
Project description:Hypothalamic glucose sensing enables an organism to match energy expenditure and food intake to circulating levels of glucose, the main energy source of the brain. Here, we established that tanycytes of the arcuate nucleus of the hypothalamus, specialized glia that line the wall of the third ventricle, convert brain glucose supplies into lactate that they transmit through monocarboxylate transporters to arcuate proopiomelanocortin neurons, which integrate this signal to drive their activity and to adapt the metabolic response to meet physiological demands. Furthermore, this transmission required the formation of extensive connexin-43 gap junction-mediated metabolic networks by arcuate tanycytes. Selective suppression of either tanycytic monocarboxylate transporters or gap junctions resulted in altered feeding behavior and energy metabolism. Tanycytic intercellular communication and lactate production are thus integral to the mechanism by which hypothalamic neurons that regulate energy and glucose homeostasis efficiently perceive alterations in systemic glucose levels as a function of the physiological state of the organism.
| S-EPMC8439611 | biostudies-literature
Project description:The molecular mechanisms underlying neuronal leptin and insulin resistance in obesity and diabetes remain unclear. Here we show that induction of the unfolded protein response transcription factor spliced X-box binding protein 1 (Xbp1s) in pro-opiomelanocortin (Pomc) neurons alone is sufficient to protect against diet-induced obesity as well as improve leptin and insulin sensitivity, even in the presence of strong activators of ER stress. We also demonstrate that constitutive expression of Xbp1s in Pomc neurons contributes to improved hepatic insulin sensitivity and suppression of endogenous glucose production. Notably, elevated Xbp1s levels in Pomc neurons also resulted in activation of the Xbp1s axis in the liver via a cell-nonautonomous mechanism. Together our results identify critical molecular mechanisms linking ER stress in arcuate Pomc neurons to acute leptin and insulin resistance as well as liver metabolism in diet-induced obesity and diabetes.
| S-EPMC4186248 | biostudies-literature
Project description:Leptin plays a pivotal role in regulation of energy balance. Via unknown central pathways, leptin also affects peripheral glucose homeostasis and locomotor activity. We hypothesized that, specifically, pro-opiomelanocortin (POMC) neurons mediate those actions. To examine this possibility, we applied Cre-Lox technology to express leptin receptors (ObRb) exclusively in POMC neurons of the morbidly obese, profoundly diabetic, and severely hypoactive leptin receptor-deficient Lepr(db/db) mice. Here, we show that expression of ObRb only in POMC neurons leads to a marked decrease in energy intake and a modest reduction in body weight in Lepr(db/db) mice. Remarkably, blood glucose levels are entirely normalized. This normalization occurs independently of changes in food intake and body weight. In addition, physical activity is greatly increased despite profound obesity. Our results suggest that leptin signaling exclusively in POMC neurons is sufficient to stimulate locomotion and prevent diabetes in the severely hypoactive and hyperglycemic obese Lepr(db/db) mice.
| S-EPMC2730605 | biostudies-other
Project description:Glycolysis-derived lactate was identified as substrate for histone lactylation, which has been regarded as a significant role in transcriptional regulation in many tissues. However, the role of histone lactylation in the metabolic center, the hypothalamus, is still unknown. Here, we show that hypothalamic pro-opiomelanocortin (POMC) neuron-specific deletion of family with sequence similarity 172, member A (Fam172a) can increase histone lactylation and protect mice against diet-induced obesity (DIO) and related metabolic disorders. Conversely, overexpression of Fam172a in POMC neurons led to an obesity-like phenotype. Using RNA-seq and CUT&Tag chromatin profiling analyses, we find that knockdown of Fam172a activates the glycolytic process and increases peptidylglycine α-amidating monooxygenase (PAM), which affects the synthesis of α-MSH, via H4K12la (histone lactylation). In addition, pharmacological inhibition of lactate production clearly abrogates the anti-obesity effect of PFKO (POMC-Cre, Fam172aloxP/loxP, POMC neurons Fam172a knockout). These findings highlight the importance of Fam172a and lactate in the development of obesity.
2024-11-06 | GSE280695 | GEO
Project description:Glycolysis-derived lactate was identified as substrate for histone lactylation, which has been regarded as a significant role in transcriptional regulation in many tissues. However, the role of histone lactylation in the metabolic center, the hypothalamus, is still unknown. Here, we show that hypothalamic pro-opiomelanocortin (POMC) neuron-specific deletion of family with sequence similarity 172, member A (Fam172a) can increase histone lactylation and protect mice against diet-induced obesity (DIO) and related metabolic disorders. Conversely, overexpression of Fam172a in POMC neurons led to an obesity-like phenotype. Using RNA-seq and CUT&Tag chromatin profiling analyses, we find that knockdown of Fam172a activates the glycolytic process and increases peptidylglycine α-amidating monooxygenase (PAM), which affects the synthesis of α-MSH, via H4K12la (histone lactylation). In addition, pharmacological inhibition of lactate production clearly abrogates the anti-obesity effect of PFKO (POMC-Cre, Fam172aloxP/loxP, POMC neurons Fam172a knockout). These findings highlight the importance of Fam172a and lactate in the development of obesity.
2024-11-06 | GSE280694 | GEO
Project description:ObjectivesInsulin signaling in the brain has been implicated in the control of satiety, glucose homeostasis and energy balance. However, insulin signaling is dispensable in energy homeostasis controlling AgRP or POMC neurons and it is unclear which other neurons regulate these effects. Here we describe an ancient insulin/NPY neuronal network that governs energy homeostasis across phyla.MethodsTo address the role of insulin action specifically in NPY neurons, we generated a variety of models by selectively removing insulin signaling in NPY neurons in flies and mice and testing the consequences on energy homeostasis.ResultsBy specifically targeting the insulin receptor in both fly and mouse NPY expressing neurons, we found NPY-specific insulin signaling controls food intake and energy expenditure, and lack of insulin signaling in NPY neurons leads to increased energy stores and an obese phenotype. Additionally, the lack of insulin signaling in NPY neurons leads to a dysregulation of GH/IGF-1 axis and to altered insulin sensitivity.ConclusionsTaken together, these results suggest that insulin actions in NPY neurons is critical for maintaining energy balance and an impairment of this pathway may be causally linked to the development of metabolic diseases.
| S-EPMC5444095 | biostudies-literature
Project description:With the steady rise in the prevalence of obesity and its associated diseases, research aimed at understanding the mechanisms that regulate and control whole body energy homeostasis has gained new interest. Leptin and insulin, two anorectic hormones, have key roles in the regulation of body weight and energy homeostasis, as highlighted by the fact that several obese patients develop resistance to these hormones. Within the brain, the hypothalamic proopiomelanocortin and agouti-related protein neurons have been identified as major targets of leptin and insulin action. Many studies have attempted to discern the individual contributions of various components of the principal pathways that mediate the central effects of leptin and insulin. The aim of this review is to discuss the latest findings that might shed light on, and lead to a better understanding of, energy balance and glucose homeostasis. In addition, recently discovered targets and mechanisms that mediate hormonal action in the brain are highlighted.
| S-EPMC3512417 | biostudies-other
Project description:We have recently demonstrated that specific overexpression of DEP-domain containing mTOR-interacting protein (DEPTOR) in the mediobasal hypothalamus (MBH) protects mice against high-fat diet-induced obesity, revealing DEPTOR as a significant contributor to energy balance regulation. On the basis of evidence that DEPTOR is expressed in the proopiomelanocortin (POMC) neurons of the MBH, the present study aimed to investigate whether these neurons mediate the metabolic effects of DEPTOR. Here, we report that specific DEPTOR overexpression in POMC neurons does not recapitulate any of the phenotypes observed when the protein was overexpressed in the MBH. Unlike the previous model, mice overexpressing DEPTOR only in POMC neurons 1) did not show differences in feeding behavior, 2) did not exhibit changes in locomotion activity and oxygen consumption, 3) did not show an improvement in systemic glucose metabolism, and 4) were not resistant to high-fat diet-induced obesity. These results support the idea that other neuronal populations are responsible for these phenotypes. Nonetheless, we observed a mild elevation in fasting blood glucose, insulin resistance, and alterations in liver glucose and lipid homeostasis in mice overexpressing DEPTOR in POMC neurons. Taken together, these results show that DEPTOR overexpression in POMC neurons does not affect energy balance regulation but could modulate metabolism through a brain-liver connection.
| S-EPMC4935503 | biostudies-literature