Identification and cloning of a β-cell-specific zinc transporter, ZnT-8, localized into insulin secretory granules
Identification and cloning of a β-cell-specific zinc transporter, ZnT-8, localized into insulin secretory granules
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DOI：
10.2337/diabetes.53.9.2330
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发表时间：
2004-09-01
期刊：
影响因子：
7.7
通讯作者：
Seve, M
中科院分区：
文献类型：
--
作者：
Chimienti, F;Devergnas, S;Seve, M
SLC3OA8是锌转运蛋白(ZNT)家族的一个新成员，它是通过搜索人类基因组和表达序列标签(EST)数据库中所有已知的人类ZNT的氨基酸序列而被鉴定的。该基因编码的蛋白质(369个氨基酸)与其他ZNT蛋白一样，含有6个跨膜区和一个位于跨膜区IV和V之间的富含组氨酸的环。通过对文库和人组织提取液进行RT-PCR实验，我们证明ZNT-8基因只在胰腺中转录，主要在朗格汉斯的胰岛中转录。该基因被克隆并测序，命名为SLC3OA8。共聚焦免疫荧光分析显示，ZNT-8-EGFP(增强型绿色荧光蛋白)融合产物与胰岛素共存于胰岛素分泌途径颗粒中。与单独表达绿色荧光蛋白的细胞相比，稳定表达ZNT-8-EGFP的HeLa细胞暴露于75mumol/L锌可引起细胞内锌的蓄积。这些结果证实ZNT-8是一种胰腺特异的ZNT，在β细胞中表达。由于ZNT-8促进锌从细胞质积累到细胞内小泡中，ZNT-8可能是胰岛素分泌的胰岛β细胞中为胰岛素成熟和/或储存过程提供锌的主要成分。
SLC3OA8, a novel member of the zinc transporter (ZnT) family, was identified by searching the human genomic and expressed sequence tag (EST) databases with the amino acid sequence of all known human ZnT. The protein (369 amino acids) predicted from this gene, ZnT-8, contains six transmembrane domains and a histidine-rich loop between transmembrane domains IV and V, like the other ZnT proteins. We demonstrated by RT-PCR on cDNA libraries and human tissue extracts that the ZnT-8 gene is solely transcribed in the pancreas, mainly in the islets of Langerhans. The gene, named SLC3OA8, was cloned and sequenced. Confocal immunofluorescence analysis revealed that a ZnT-8-EGFP (enhanced green fluorescent protein) fusion product colocalized with insulin in the secretory pathway granules of the insulin-secreting INS-1 cells. Exposure of the ZnT-8-EGFP stably expressing HeLa cells to 75 mumol/l zinc caused an accumulation of zinc in intracellular vesicles compared with cells expressing EGFP alone. These results identified ZnT-8 as a ZnT specific to the pancreas and expressed in beta-cells. Because ZnT-8 facilitates the accumulation of zinc from the cytoplasm into intracellular vesicles, ZnT-8 may be a major component for providing zinc to insulin maturation and/or storage processes in insulin-secreting pancreatic beta-cells.