Dataset Information

Amylin receptor insensitivity impairs hypothalamic POMC neuron differentiation in the male offspring of maternal high-fat diet-fed mice.

ABSTRACT:

Objective

Amylin was found to regulate glucose and lipid metabolism by acting on the arcuate nucleus of the hypothalamus (ARC). Maternal high-fat diet (HFD) induces sex-specific metabolic diseases mediated by the ARC in offspring. This study was performed to explore 1) the effect of maternal HFD-induced alterations in amylin on the differentiation of hypothalamic neurons and metabolic disorders in male offspring and 2) the specific molecular mechanism underlying the regulation of amylin and its receptor in response to maternal HFD.

Methods

Maternal HFD and gestational hyper-amylin mice models were established to explore the role of hypothalamic amylin and receptor activity-modifying protein 3 (Ramp3) in regulating offspring metabolism. RNA pull-down, mass spectrometry, RNA immunoprecipitation, and RNA decay assays were performed to investigate the mechanism underlying the influence of maternal HFD on Ramp3 deficiency in the fetal hypothalamus.

Results

Male offspring with maternal HFD grew heavier and developed metabolic disorders, whereas female offspring with maternal HFD showed a slight increase in body weight and did not develop metabolic disorders compared to those exposed to maternal normal chow diet (NCD). Male offspring exposed to a maternal HFD had hyperamylinemia from birth until adulthood, which was inconsistent with offspring exposed to maternal NCD. Hyperamylinemia in the maternal HFD-exposed male offspring might be attributed to amylin accumulation following Ramp3 deficiency in the fetal hypothalamus. After Ramp3 knockdown in hypothalamic neural stem cells (htNSCs), amylin was found to fail to promote the differentiation of anorexigenic alpha-melanocyte-stimulating hormone-proopiomelanocortin (?-MSH-POMC) neurons but not orexigenic agouti-related protein-neuropeptide Y (AgRP-Npy) neurons. An investigation of the mechanism involved showed that IGF2BP1 could specifically bind to Ramp3 in htNSCs and maintain its mRNA stability. Downregulation of IGF2BP1 in htNSCs in the HFD group could decrease Ramp3 expression and lead to an impairment of ?-MSH-POMC neuron differentiation.

Conclusions

These findings suggest that gestational exposure to HFD decreases the expression of IGF2BP1 in the hypothalami of male offspring and destabilizes Ramp3 mRNA, which leads to amylin resistance. The subsequent impairment of POMC neuron differentiation induces sex-specific metabolic disorders in adulthood.

SUBMITTER: Li C

PROVIDER: S-EPMC7773963 | biostudies-literature | 2020 Dec

REPOSITORIES: biostudies-literature

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Publications

Amylin receptor insensitivity impairs hypothalamic POMC neuron differentiation in the male offspring of maternal high-fat diet-fed mice.

Li Cheng C Xu Jing-Jing JJ Hu Hong-Tao HT Shi Chao-Yi CY Yu Chuan-Jin CJ Sheng Jian-Zhong JZ Wu Yan-Ting YT Huang He-Feng HF

Molecular metabolism 20201203

<h4>Objective</h4>Amylin was found to regulate glucose and lipid metabolism by acting on the arcuate nucleus of the hypothalamus (ARC). Maternal high-fat diet (HFD) induces sex-specific metabolic diseases mediated by the ARC in offspring. This study was performed to explore 1) the effect of maternal HFD-induced alterations in amylin on the differentiation of hypothalamic neurons and metabolic disorders in male offspring and 2) the specific molecular mechanism underlying the regulation of amylin ...[more]

PMID: 33279727

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Project description:BackgroundEpidemiological and animal studies have reported that prenatal nicotine exposure (PNE) leads to obesity and type-2 diabetes in offspring. Central leptin-melanocortin signaling via hypothalamic arcuate proopiomelanocortin (POMC) neurons is crucial for the regulation of energy and glucose balance. Furthermore, hypothalamic POMC neurons were recently found to mediate the anorectic effects of nicotine through activation of acetylcholine receptors. Here, we hypothesized that PNE impairs leptin-melanocortinergic regulation of energy balance in first-generation offspring by altering expression of long non-coding RNAs (lncRNAs) putatively regulating development and/or function of hypothalamic POMC neurons.MethodsC57BL/6J females were exposed ad libitum to nicotine through drinking water and crossed with C57BL/6J males. Nicotine exposure was sustained during pregnancy and discontinued at parturition. Offspring development was monitored from birth into adulthood. From the age of 8 weeks, central leptin-melanocortin signaling, diabetes, and obesity susceptibility were assessed in male offspring fed a low-fat or high-fat diet for 16 weeks. Nicotine-exposed and non-exposed C57BL/6J females were also crossed with C57BL/6J males expressing the enhanced green fluorescent protein specifically in POMC neurons. Transgenic male offspring were subjected to laser microdissections and RNA sequencing (RNA-seq) analysis of POMC neurons for determination of nicotine-induced gene expression changes and regulatory lncRNA/protein-coding gene interactions.ResultsContrary to expectation based on previous studies, PNE did not impair but rather enhanced leptin-melanocortinergic regulation of energy and glucose balance via POMC neurons in offspring. RNA-seq of laser microdissected POMC neurons revealed only one consistent change, upregulation of Gm15851, a lncRNA of yet unidentified function, in nicotine-exposed offspring. RNA-seq further suggested 82 cis-regulatory lncRNA/protein-coding gene interactions, 19 of which involved coding genes regulating neural development and/or function, and revealed expression of several previously unidentified metabolic, neuroendocrine, and neurodevelopment pathways in POMC neurons.ConclusionsPNE does not result in obesity and type 2 diabetes but instead enhances leptin-melanocortinergic feeding and body weight regulation via POMC neurons in adult offspring. PNE leads to selective upregulation of Gm15851, a lncRNA, in adult offspring POMC neurons. POMC neurons express several lncRNAs and pathways possibly regulating POMC neuronal development and/or function.

Project description:Substantial evidence indicated that maternal malnutrition could increase the susceptibility to obesity, insulin resistance, and type 2 diabetes in adulthood. It is increasingly apparent that the brain, especially the hypothalamus, plays a critical role in glucose homeostasis. However, little information is known about the mechanisms linking maternal protein restriction combined with post-weaning high-fat (HF) feeding with altered expression of brain neurotransmitters, and investigations into the epigenetic modifications of hypothalamus in offspring have not been fully elucidated. Our objective was to explore the effects of maternal protein restriction combined with post-weaning HF feeding on glucose metabolism and hypothalamic POMC methylation in male offspring mice. C57/BL6 mice were fed on either low-protein (LP) or normal chow (NC) diet throughout gestation and lactation. Then, the male offspring were randomly weaned to either NC or high-fat (HF) diet until 32 weeks of age. Gene expressions and DNA methylation of hypothalamic proopiomelanocortin (POMC) and melanocortin receptor 4 (MC4R) were determined in male offspring. The results showed that birth weights and body weights at weaning were both significantly lower in male offspring mice of the dams fed with a LP diet. Maternal protein restriction combined with post-weaning high-fat feeding, predisposes higher body weight, persistent glucose intolerance (from weaning to 32 weeks of age), hyperinsulinemia, and hyperleptinemia in male offspring mice. POMC and MC4R expressions were significantly increased in offspring mice fed with maternal LP and postnatal high-fat diet (P < 0.05). Furthermore, maternal protein restriction combined with post-weaning high-fat feeding induced hypomethylation of POMC promoter in the hypothalamus (P < 0.05) and POMC-specific methylation (%) was negatively correlated with the glucose response to a glucose load in male offspring mice (r = -0.42, P = 0.039). In conclusion, maternal LP diet combined with post-weaning high-fat feeding predisposed the male offspring to impaired glucose metabolism and hypothalamic POMC hypomethylation. These findings can advance our thinking about hypothalamic POMC gene methylation between maternal LP diet combined with post-weaning high-fat feeding and metabolic health in offspring.

Project description:ObjectiveProopiomelanocortin (POMC) neurons release potent anorexigenic neuropeptides, which suppress food intake and enhance energy expenditure via melanocortin receptors. Although the importance of central melanocortin in physiological regulation is well established, the underlying genetic mechanisms that define the functional identity of melanocortin neurons and maintain hypothalamic Pomc expression remain to be fully determined. In this study, we investigate the functional significance of Six3, a transcriptional regulator notably expressed in embryonic and adult mouse POMC neurons, in the regulation of hypothalamic Pomc expression and downstream physiological consequences.MethodsWe first evaluated the expression of Six3 in the developing and adult hypothalamus by double fluorescence in situ hybridization. Next, we assessed POMC immunoreactivity in mutant mice selectively lacking Six3 from Pomc-expressing neurons and quantified Pomc mRNA levels in a tamoxifen-inducible Six3 knockout mouse model activated at embryonic E9.5 days. We also determined glucose and insulin sensitivity, daily food intake, body composition and body weight in adult male and female mice lacking Six3 specifically from POMC neurons. Lastly, we assessed the physiological consequences of ablating Six3 from POMC neurons in adult mice.ResultsSix3 and Pomc were co-expressed in mouse hypothalamic neurons during development and adulthood. Mouse embryos deficient in Six3 showed reduced Pomc expression in the developing hypothalamus. Targeted deletion of Six3 specifically from POMC neurons resulted in decreased hypothalamic Pomc expression, increased daily food intake, enhanced glucose sensitivity and mild obesity in male but not in female mice. Finally, conditional removal of Six3 from POMC neurons in adult mice led to a reduction in hypothalamic POMC immunoreactivity with no significant effects in body weight or food intake.ConclusionsAltogether, our results demonstrate that Six3 plays an essential role in the early establishment of POMC neuron identity and the maintenance of physiological levels of hypothalamic Pomc expression. In addition, our study demonstrates that the functional significance of Six3 expression in POMC neurons is sexually dimorphic and age-dependent.

Dataset Information

Amylin receptor insensitivity impairs hypothalamic POMC neuron differentiation in the male offspring of maternal high-fat diet-fed mice.

Objective

Methods

Results

Conclusions

Publications

Amylin receptor insensitivity impairs hypothalamic POMC neuron differentiation in the male offspring of maternal high-fat diet-fed mice.

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