Ganglioside deficiency in hypothalamic POMC neurons promotes body weight gain
Ganglioside deficiency in hypothalamic POMC neurons promotes body weight gain
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DOI：
10.1038/s41366-019-0388-y
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发表时间：
2020-02-01
影响因子：
4.9
通讯作者：
Nordstroem, V
中科院分区：
文献类型：
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作者：
Dieterle, V;Herzer, S.;Nordstroem, V
背景葡萄糖神经酰胺合酶（GCS;基因：UDP-葡萄糖：神经酰胺葡萄糖基转移酶（Ugcg））衍生的神经节苷脂包含质膜中调节跨膜受体活性的一类特定脂质。下丘脑弓状核（Arc）神经元中GCS缺失导致显著肥胖。然而，尚未研究神经节苷脂耗竭如何影响单个Arc神经元亚群。目前的研究探讨GCS缺失的影响，特别是在apoxigenic pro-opiomelanocortin（POMC）神经元。此外，我们研究胰岛素受体（IR）信号和磷脂酰肌醇-（3，4，5）-三磷酸（PIP 3）结合ATP依赖性K+（K-ATP）通道的GCS缺陷POMC神经元。材料和方法我们产生了POMC神经元中神经节苷脂缺乏的Ugcgf/f-Pomc-Cre小鼠。此外，CRISPR（成簇调节间隔短回文重复序列）/Cas9技术用于抑制培养的小鼠POMC神经元中的GCS依赖性神经节苷脂生物合成，产生Ugcg（Delta）-mHypoA-POMC细胞，其用于进一步详细研究机制方面。邻近连接试验（PLA）显示了神经节苷脂、IR和K-ATP通道亚单位磺酰脲受体-1（SUR-1）以及细胞内IR底物2（IRS-2）磷酸化和PIP 3之间的相互作用。结果喂食饲料的Ugcgf/f-Pomc-Cre小鼠表现出中等但显著的体重增加，并且在禁食到再喂食的过渡期间，它们未能表现出促氧化神经肽表达的增加。IR、IRS-2、p85和总体胰岛素诱发的IR和IRS-2磷酸化在神经节苷脂耗尽的Ugcg（Delta）-mHypoA-POMC神经元中升高。PLA表明，在神经节苷脂缺乏的POMC神经元中，在体外和体内，PIP 3和SUR-1之间发生了更多的胰岛素诱发的复合物形成。结论POMC神经元GCS缺失促进体重增加。神经节苷脂是在禁食到再进食过渡期间适当适应Arc中的促氧化神经肽表达所必需的。此外，神经节苷脂可能通过抑制PIP 3与K-ATP通道亚基SUR-1的结合来调节K-ATP通道活性。在神经节苷脂缺乏的神经元中增加的PIP 3/SUR-1相互作用反过来可能导致电沉默。这项工作强调了下丘脑弧POMC神经元中的神经节苷脂是体重的重要调节剂。
Background Glucosylceramide synthase (GCS; gene: UDP-glucose:ceramide glucosyltransferase (Ugcg))-derived gangliosides comprise a specific class of lipids in the plasma membrane that modulate the activity of transmembrane receptors. GCS deletion in hypothalamic arcuate nucleus (Arc) neurons leads to prominent obesity. However, it has not yet been studied how ganglioside depletion affects individual Arc neuronal subpopulations. The current study investigates the effects of GCS deletion specifically in anorexigenic pro-opiomelanocortin (POMC) neurons. Additionally, we investigate insulin receptor (IR) signaling and phosphatidylinositol-(3,4,5)-trisphosphate (PIP3) binding to ATP-dependent K+ (K-ATP) channels of GCS-deficient POMC neurons. Materials and methods We generated Ugcgf/f-Pomc-Cre mice with ganglioside deficiency in POMC neurons. Moreover, the CRISPR (clustered regulatory interspaced short palindromic repeats)/Cas9 technology was used to inhibit GCS-dependent ganglioside biosynthesis in cultured mouse POMC neurons, yielding Ugcg(Delta)-mHypoA-POMC cells that were used to study mechanistic aspects in further detail. Proximity ligation assays (PLAs) visualized interactions between gangliosides, IR, and K-ATP channel subunit sulfonylurea receptor-1 (SUR-1), as well as intracellular IR substrate 2 (IRS-2) phosphorylation and PIP3. Results Chow-fed Ugcgf/f-Pomc-Cre mice showed a moderate but significant increase in body weight gain and they failed to display an increase of anorexigenic neuropeptide expression during the fasting-to-re-feeding transition. IR, IRS-2, p85, and overall insulin-evoked IR and IRS-2 phosphorylation were elevated in ganglioside-depleted Ugcg(Delta)-mHypoA-POMC neurons. A PLA demonstrated that more insulin-evoked complex formation occurred between PIP3 and SUR-1 in ganglioside-deficient POMC neurons in vitro and in vivo. Conclusion Our work suggests that GCS deletion in POMC neurons promotes body weight gain. Gangliosides are required for an appropriate adaptation of anorexigenic neuropeptide expression in the Arc during the fasting-to-re-feeding transition. Moreover, gangliosides might modulate K-ATP channel activity by restraining PIP3 binding to the K-ATP channel subunit SUR-1. Increased PIP3/SUR-1 interactions in ganglioside-deficient neurons could in turn potentially lead to electrical silencing. This work highlights that gangliosides in POMC neurons of the hypothalamic Arc are important regulators of body weight.