Secretogranin III (SgIII) is a granin protein involved in secretory granule formation in peptide-hormone-producing endocrine cells. In this study, we analyzed the expression of the LacZ reporter in the SgIII knockout mice produced by gene trapping (SgIII-gtKO) for the purpose of comprehensively clarifying the expression patterns of SgIII at the cell and tissue levels. In the endocrine tissues of SgIII-gtKO mice, LacZ expression was observed in the pituitary gland, adrenal medulla, and pancreatic islets, where SgIII expression has been canonically revealed. LacZ expression was extensively observed in brain regions, especially in the cerebral cortex, hippocampus, hypothalamic nuclei, cerebellum, and spinal cord. In peripheral nervous tissues, LacZ expression was observed in the retina, optic nerve, and trigeminal ganglion. LacZ expression was particularly prominent in astrocytes, in addition to neurons and ependymal cells. In the cerebellum, at least four cell types expressed SgIII under basal conditions. The expression of SgIII in the glioma cell lines C6 and RGC-6 was enhanced by excitatory glutamate treatment. It also became clear that the expression level of SgIII varied among neuron and astrocyte subtypes. These results suggest that SgIII is involved in glial cell function, in addition to neuroendocrine functions, in the nervous system:

分泌粒蛋白 III (SgIII) 是一种粒蛋白，参与产生肽激素的内分泌细胞的分泌颗粒形成。在本研究中，我们分析了基因捕获产生的SgIII敲除小鼠（SgIII-gtKO ）中LacZ报告基因的表达，以全面阐明SgIII在细胞和组织水平上的表达模式。在SgIII-gtKO小鼠的内分泌组织中，在垂体、肾上腺髓质和胰岛中观察到LacZ表达，其中 SgIII 表达已被规范地揭示。紫胶在大脑区域广泛观察到表达，特别是在大脑皮层、海马、下丘脑核、小脑和脊髓。在周围神经组织中，在视网膜、视神经和三叉神经节中观察到LacZ表达。除了神经元和室管膜细胞外，LacZ表达在星形胶质细胞中尤为突出。在小脑中，至少有四种细胞类型在基础条件下表达 SgIII。兴奋性谷氨酸处理增强了胶质瘤细胞系 C6 和 RGC-6 中 SgIII 的表达。还清楚的是，SgIII 的表达水平在神经元和星形胶质细胞亚型之间有所不同。这些结果表明，除了神经内分泌功能外，SgIII 还参与神经系统中的神经胶质细胞功能：