Cell Isolation and Transplantation Center, Department of Surgery, Geneva University Hospitals and University of Geneva, 1211 Geneva 4, Switzerland.
Endocrinology. 2011 Dec;152(12):4601-9. doi: 10.1210/en.2011-1286. Epub 2011 Oct 11.
The aim of this study was to assess the expression of different types of cadherins in human islets and their role in human β-cell apoptosis. Expression of E-, N-, and P-cadherins was studied by immunofluorescence on pancreas sections and islet cells, and by Western blotting on protein extracts of isolated islets and islet cells. The effects of specific cadherins on cell adhesion and apoptosis were studied using chimeric proteins containing functional E-, N-, or P-cadherin ectodomains fused to Fc fragment of Ig (E-cad/Fc, N-cad/Fc, and P-cad/Fc) and immobilized on glass substrate. β-Cells were identified by immunofluorescence for insulin and apoptotic cells by terminal deoxynucleotide transferase-mediated 2'-deoxyuridine, 5'-triphosphate nick-end labeling. By immunofluorescence, we showed that E- and N-, and not P-, cadherins were expressed at the surface of islet cells. By triple staining, we showed that E-cadherin was expressed at similar extent in β- and α-cells, whereas N-cadherin was preferentially expressed in β-cells. These results were confirmed by Western blot analysis using protein extracts from fluorescence-activated cell sorting-sorted β- and non-β-cells. Adhesion tests showed that the affinity of islet cells for E-cad/Fc and N-cad/Fc and not for P-cad/Fc was increased compared with control. By terminal deoxynucleotide transferase-mediated 2'-deoxyuridine, 5'-triphosphate nick-end labeling, we showed that the percentage of apoptotic cells was lower in aggregated β-cells compared with single β-cells and that attachment to E-cad/Fc and N-cad/Fc and not to P-cad/Fc decreased apoptosis of single β-cells compared with control. Our results show that at least E- and N-cadherins are expressed at the surface of human β-cells and that these adhesion molecules are involved in the maintenance of β-cell viability.
本研究旨在评估不同类型钙黏蛋白在人胰岛中的表达及其在人β细胞凋亡中的作用。通过免疫荧光法在胰腺切片和胰岛细胞上研究 E、N 和 P 钙黏蛋白的表达,并通过Western 印迹法在分离的胰岛和胰岛细胞的蛋白质提取物上研究。使用含有功能性 E、N 或 P 钙黏蛋白外显子融合到 IgG Fc 片段的嵌合蛋白(E-cad/Fc、N-cad/Fc 和 P-cad/Fc),并将其固定在玻璃基质上,研究特定钙黏蛋白对细胞黏附和凋亡的影响。通过胰岛素免疫荧光鉴定β细胞,通过末端脱氧核苷酸转移酶介导的 2'-脱氧尿苷、5'-三磷酸末端标记鉴定凋亡细胞。通过免疫荧光,我们显示 E 和 N 钙黏蛋白,但不是 P 钙黏蛋白,在胰岛细胞表面表达。通过三重染色,我们显示 E-钙黏蛋白在β和α细胞中的表达程度相似,而 N-钙黏蛋白在β细胞中优先表达。这些结果通过使用荧光激活细胞分选分离的β和非β细胞的蛋白质提取物进行 Western blot 分析得到证实。黏附试验表明,与对照相比,胰岛细胞对 E-cad/Fc 和 N-cad/Fc 的亲和力增加,但对 P-cad/Fc 的亲和力没有增加。通过末端脱氧核苷酸转移酶介导的 2'-脱氧尿苷、5'-三磷酸末端标记,我们显示与单个β细胞相比,聚集的β细胞中的凋亡细胞百分比较低,并且与 E-cad/Fc 和 N-cad/Fc 而不是 P-cad/Fc 的附着降低了单个β细胞的凋亡与对照相比。我们的结果表明,至少 E 和 N 钙黏蛋白在人β细胞表面表达,并且这些黏附分子参与维持β细胞活力。