Department of Clinical Sciences, Islet Pathophysiology, Lund University Diabetes Centre, Jan Waldenströms gata 35, , Malmö, Sweden.
Diabetologia. 2013 Feb;56(2):340-9. doi: 10.1007/s00125-012-2758-z. Epub 2012 Nov 15.
AIMS/HYPOTHESIS: Voltage-gated calcium channels of the L-type have been shown to be essential for rodent pancreatic beta cell function, but data about their presence and regulation in humans are incomplete. We therefore sought to elucidate which L-type channel isoform is functionally important and its association with inherited diabetes-related phenotypes.
Beta cells of human islets from cadaver donors were enriched using FACS to study the expression of the genes encoding voltage-gated calcium channel (Cav)1.2 and Cav1.3 by absolute quantitative PCR in whole human and rat islets, as well as in clonal cells. Single-cell exocytosis was monitored as increases in cell capacitance after treatment with small interfering (si)RNA against CACNA1D (which encodes Cav1.3). Three single nucleotide polymorphisms (SNPs) were genotyped in 8,987 non-diabetic and 2,830 type 2 diabetic individuals from Finland and Sweden and analysed for associations with type 2 diabetes and insulin phenotypes.
In FACS-enriched human beta cells, CACNA1D mRNA expression exceeded that of CACNA1C (which encodes Cav1.2) by approximately 60-fold and was decreased in islets from type 2 diabetes patients. The latter coincided with diminished secretion of insulin in vitro. CACNA1D siRNA reduced glucose-stimulated insulin release in INS-1 832/13 cells and exocytosis in human beta cells. Phenotype/genotype associations of three SNPs in the CACNA1D gene revealed an association between the C allele of the SNP rs312480 and reduced mRNA expression, as well as decreased insulin secretion in vivo, whereas both rs312486/G and rs9841978/G were associated with type 2 diabetes.
CONCLUSION/INTERPRETATION: We conclude that the L-type calcium channel Cav1.3 is important in human glucose-induced insulin secretion, and common variants in CACNA1D might contribute to type 2 diabetes.
目的/假设：已证实 L 型电压门控钙通道对于啮齿动物胰腺β细胞功能至关重要，但有关其在人类中的存在和调节的数据并不完整。因此，我们试图阐明哪种 L 型通道同工型在功能上很重要，以及它与遗传性糖尿病相关表型的关联。
使用 FACS 从尸体供者的胰岛中富集β细胞，以通过绝对定量 PCR 研究编码电压门控钙通道 (Cav)1.2 和 Cav1.3 的基因在整个人和大鼠胰岛以及克隆细胞中的表达。使用针对 CACNA1D（编码 Cav1.3）的小干扰 (si)RNA 处理后，监测单细胞胞吐作用作为细胞电容增加。在芬兰和瑞典的 8987 名非糖尿病和 2830 名 2 型糖尿病个体中对 3 个单核苷酸多态性 (SNP) 进行基因分型，并分析其与 2 型糖尿病和胰岛素表型的关联。
在 FACS 富集的人类β细胞中，CACNA1D mRNA 表达超过 CACNA1C（编码 Cav1.2）约 60 倍，并且在 2 型糖尿病患者的胰岛中减少。后者与体外胰岛素分泌减少相吻合。CACNA1D siRNA 减少 INS-1 832/13 细胞中的葡萄糖刺激的胰岛素释放和人β细胞中的胞吐作用。CACNA1D 基因中三个 SNP 的表型/基因型关联显示，SNP rs312480 的 C 等位基因与 mRNA 表达减少以及体内胰岛素分泌减少相关，而 rs312486/G 和 rs9841978/G 均与 2 型糖尿病相关。
结论/解释：我们得出结论，L 型钙通道 Cav1.3 在人类葡萄糖诱导的胰岛素分泌中很重要，CACNA1D 中的常见变异可能导致 2 型糖尿病。
