Department of Diabetes and Clinical Nutrition, Graduate School of Medicine, Kyoto University, Kyoto.
Department of Medicine and Biosystemic Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
J Diabetes Investig. 2012 Feb 20;3(1):52-61. doi: 10.1111/j.2040-1124.2011.00138.x.
Aims/Introduction: Insulinoma-associated protein 2 (IA-2) regulates insulin secretion and the number of dense core vesicles (DCV). However, the mechanism of regulation of DCV number by IA-2 is unknown. We examined the effect of sorting nexin 19 (SNX19), an IA-2 interacting protein, on insulin secretion and the number of dense core vesicles (DCV).
Stable SNX19 knockdown (SNX19KD) MIN6, a mouse pancreatic β-cell line, and stable SNX19-reintroduced SNX19KD MIN6 were established. Quantification of DCV, and lysosomes was carried out using electron micrographs. The half-life of DCV was detected by pulse-chase experiment.
Insulin secretion and content were decreased in stable SNX19KD MIN6 cells compared with those in control MIN6 cells. Electron micrographs showed that DCV number in SNX19KD cells was decreased by approximately 75% and that DCV size was decreased by approximately 40% compared with those in control cells, respectively. Furthermore, when SNX19 was reintroduced in SNX19KD cells, insulin content, insulin secretion and DCV number were increased. The half-life of DCV was decreased in SNX19KD cells, but was increased in SNX19KD cells in which SNX19 was reintroduced. The number of lysosomes and the activity of lysosome enzyme cathepsin D were increased by approximately threefold in SNX19KD cells compared with those in control cells. In contrast, they were decreased to approximately half to one-third in SNX19-reintroduced SNX19KD cells.
SNX19 regulates the number of DCV and insulin content by stabilizing DCV in β-cells. (J Diabetes Invest, doi: 10.1111/j.2040-1124.2011.00138.x, 2012).
目的/引言：胰岛素瘤相关蛋白 2（IA-2）调节胰岛素分泌和致密核心囊泡（DCV）的数量。然而，IA-2 调节 DCV 数量的机制尚不清楚。我们研究了 IA-2 相互作用蛋白分选连接蛋白 19（SNX19）对胰岛素分泌和致密核心囊泡（DCV）数量的影响。
建立了稳定的 SNX19 敲低（SNX19KD）MIN6，一种小鼠胰腺β细胞系，和稳定的 SNX19 再引入 SNX19KD MIN6。使用电子显微镜定量 DCV 和溶酶体。通过脉冲追踪实验检测 DCV 的半衰期。
与对照 MIN6 细胞相比，稳定的 SNX19KD MIN6 细胞中的胰岛素分泌和含量降低。电子显微镜显示，SNX19KD 细胞中的 DCV 数量减少了约 75%，DCV 大小减少了约 40%，与对照细胞相比。此外，当 SNX19 在 SNX19KD 细胞中重新引入时，胰岛素含量、胰岛素分泌和 DCV 数量增加。SNX19KD 细胞中 DCV 的半衰期缩短，但在重新引入 SNX19 的 SNX19KD 细胞中增加。SNX19KD 细胞中的溶酶体数量和溶酶体酶组织蛋白酶 D 的活性增加了约三倍，与对照细胞相比。相比之下，它们在重新引入 SNX19 的 SNX19KD 细胞中减少到大约一半到三分之一。
SNX19 通过稳定β细胞中的 DCV 来调节 DCV 的数量和胰岛素含量。（糖尿病研究杂志，doi：10.1111/j.2040-1124.2011.00138.x，2012）。
