Pancreatic β-cells in the Islets of Langerhans are key to maintaining glucose homeostasis, by secreting the peptide hormone insulin. Insulin is packaged within vesicles named insulin secretory granules (ISGs), that have recently been considered to have intrinsic structures and proteins that regulate insulin granule maturation, trafficking, and secretion. Previously, studies have identified a handful of novel ISG-associated proteins using different separation techniques. Here, this study combines an optimized ISG isolation technique and mass spectrometry-based proteomics, with an unbiased protein correlation profiling and targeted machine learning approach to uncover 211 ISG-associated proteins with confidence. Four of these proteins: Syntaxin-7, Synaptophysin, Synaptotagmin-13 and Scamp3 have not been previously ISG-associated. Through colocalization analysis of confocal imaging we validate the association of these proteins to the ISG in MIN6 and human β-cells. We further validate the role for one (Scamp3) in regulating insulin content and secretion from β-cells for the first time. Scamp3 knock-down INS-1 cells show a reduction in insulin content and dysfunctional insulin secretion. These data provide the basis for future investigation of Scamp3 in β-cell biology and the regulation of insulin secretion.

中文翻译：

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对 MIN6 细胞的胰岛素颗粒进行优化的蛋白质组学分析，确定了 Scamp3，这是一种胰岛素分泌和含量的新型调节因子。


朗格汉斯岛的胰腺 β 细胞通过分泌肽激素胰岛素来维持葡萄糖稳态。胰岛素包装在称为胰岛素分泌颗粒 （ISG） 的囊泡中，最近被认为具有调节胰岛素颗粒成熟、运输和分泌的内在结构和蛋白质。以前，研究使用不同的分离技术鉴定了一些新型 ISG 相关蛋白。在这里，这项研究将优化的 ISG 分离技术和基于质谱的蛋白质组学，与无偏倚的蛋白质相关性分析和靶向机器学习方法相结合，以自信地发现 211 种 ISG 相关蛋白质。其中四种蛋白：Syntaxin-7、Synaptophysin、Synaptotagmin-13 和 Scamp3 以前没有与 ISG 相关。通过共聚焦成像的共定位分析，我们验证了这些蛋白质与 MIN6 和人 β 细胞中 ISG 的结合。我们进一步验证了 one （Scamp3） 在调节胰岛素含量和 β 细胞分泌中的作用。Scamp3 敲低 INS-1 细胞显示胰岛素含量降低和胰岛素分泌功能障碍。这些数据为未来研究 Scamp3 在β细胞生物学和胰岛素分泌调节方面提供了基础。