成熟POMC神经元中能量稳态相关microRNA的鉴定

Overweight and obesity are pathological conditions characterized by an excessive fat accumulation. Within the central nervous system, the arcuate hypothalamic nucleus plays one of the crucial roles in energy metabolism control while proopiomelanocortin (POMC) neurons represent a primary sensory system in this region. Hormonal and nutritional inputs to these neurons are further transmitted to various hypothalamic and extra-hypothalamic regions. The objective of this project is to reveal specific microRNAs related to energy homeostasis and their targets in these neurons. MicroRNAs fine-tune gene expression by inhibiting the translation and/or stability of mRNAs. Previously, we have discovered that the loss of microRNAs in the arcuate nucleus can induce PI3K-Akt-mTOR-mediated Hyperphagic obesity. In this study, using our original in vivo microRNA delivery reductionist approach and an unbiased in vitro microRNA screening, we will identify specific microRNAs implicated in PI3K-AKT-mTOR pathway-mediated metabolic regulation. Moreover, we plan to detect RISC-associated microRNAs and mRNAs in POMC neurons in normal, high fat diet, and calorie restricted conditions. Further, functional studies on POMC neurons will be combined with target verification to explore the mechanism underlying the obesity phenotype. Beyond deciphering the roles of the microRNA pathway in physiological and pathophysiological processes, these studies are of immense relevance for basic and clinical metabolic disease research, as well as for development of novel therapeutic strategies to treat metabolic diseases.

能量稳态系统的渐进性代谢疾病会导致超重和肥胖。中枢神经系统，尤其下丘脑在能量稳态中发挥着重要作用。本项目旨在研究能量稳态相关microRNA及靶点在阿黑皮素原(POMC)神经元中的作用。MicroRNA是一种能够抑制基因转录物的翻译或稳定性的非编码RNA。本课题组前期的研究证实，下丘脑弓状核microRNA的缺失能够诱导PI3K-AKT-mTOR介导的肥胖。POMC神经元是弓状核内的一级感受系统。POMC神经元能够对激素和营养信号做出反应，并且调控效应器的功能。我们将通过体内实验和体外实验筛选和鉴定microRNA。值得注意的是，我们计划检测正常状态和代谢压力下POMC神经元中RISC相关的microRNA和mRNA。将POMC神经元的功能研究和microRNA的靶点及通路验证结合，本研究为探索肥胖表型的分子机制提供可能，也有助于开发新的代谢性疾病治疗手段。

能量稳态由下丘脑弓状核 (ARH) 内的各种神经元控制，其中许多神经元在发育上起源于表达阿片黑皮质素原(Pomc)的谱系。Pomc神经元中phosphatidylinositol-3-kinase (PI3K)-Akt-mammalian target of rapamycin (mTOR)通路的年龄依赖性过度激活导致其超极化导致肥胖。在这项工作中，我们已将miR-29家族鉴定为PI3K-Akt-mTOR通路的重要调节因子。然后，我们在老年或年轻的成年小鼠中使用miR-29a-3p模拟物递送或Cre依赖性的敲除策略，证明了这种miRNA在源自Pomc谱系的成熟神经元中的表达可以防止肥胖、食欲过盛和胰岛素抵抗。此外，在PI3K-Akt通路中，我们确定了miR-29a-3p的直接靶标Nras，它仅在CRISPR-Cas9靶向敲除miR-29a-3p的神经元中被上调。此外，相同神经元中Nras的共缺失减弱了miR-29家族缺失诱导的肥胖。这项工作显著扩展了我们对下丘脑中 miRNA 参与稳态调节的研究。