Yang Jichun, Robert Claudia E, Burkhardt Brant R, Young Robert A, Wu Jianmei, Gao Zhiyong, Wolf Bryan A
Department of Pathology and Laboratory Medicine, The Children's Hospital of Philadelphia, Philadelphia, PA 19104-4399, USA.
Diabetes. 2005 Nov;54(11):3217-28. doi: 10.2337/diabetes.54.11.3217.
Pancreatic-derived factor (PANDER) is an islet-specific cytokine present in both pancreatic alpha- and beta-cells, which, in vitro, induces beta-cell apoptosis of primary islet and cell lines. In this study, we investigated whether PANDER is secreted by pancreatic alpha- and beta-cells and whether PANDER secretion is regulated by glucose and other insulin secretagogues. In mouse-derived insulin-secreting beta-TC3 cells, PANDER secretion in the presence of stimulatory concentrations of glucose was 2.8 +/- 0.4-fold higher (P < 0.05) than without glucose. Insulin secretion was similarly increased by glucose in the same cells. The total concentration of secreted PANDER in the medium was approximately 6-10 ng/ml (0.3-0.5 nmol/l) after a 24-h culture with glucose. L-Glucose failed to stimulate PANDER secretion in beta-TC3 cells. KCl stimulated PANDER secretion 2.1 +/- 0.1-fold compared with control without glucose. An L-type Ca2+ channel inhibitor, nifedipine, completely blocked both glucose- or KCl-induced insulin and PANDER secretion. In rat-derived INS-1 cells, glucose (20 mmol/l) stimulated PANDER secretion 4.4 +/- 0.9-fold, while leucine plus glutamine stimulated 4.4 +/- 0.7-fold compared with control without glucose. In mouse islets overexpressing PANDER, glucose (20 mmol/l) stimulated PANDER secretion 3.2 +/- 0.5-fold (P < 0.05) compared with basal (3 mmol/l glucose). PANDER was also secreted by alpha-TC3 cells but was not stimulated by glucose. Mutations of cysteine 229 or of cysteines 91 and 229 to serine, which may form one disulfide bond, and truncation of the COOH-terminus or NH2-terminus of PANDER all resulted in failure of PANDER secretion, even though these mutant or truncated PANDERs were highly expressed within the cells. In conclusion, we found that 1) PANDER is secreted from both pancreatic alpha- and beta-cells, 2) glucose stimulates PANDER secretion dose dependently in beta-cell lines and primary islets but not in alpha-cells, 3) PANDER is likely cosecreted with insulin via the same regulatory mechanisms, and 4) structure and conformation is vital for PANDER secretion.
胰腺衍生因子（PANDER）是一种在胰岛α细胞和β细胞中均存在的胰岛特异性细胞因子，在体外可诱导原代胰岛和细胞系的β细胞凋亡。在本研究中，我们调查了PANDER是否由胰腺α细胞和β细胞分泌，以及PANDER的分泌是否受葡萄糖和其他胰岛素促分泌剂的调节。在小鼠来源的胰岛素分泌β-TC3细胞中，在刺激浓度的葡萄糖存在下，PANDER的分泌比无葡萄糖时高2.8±0.4倍（P<0.05）。相同细胞中胰岛素分泌也因葡萄糖而类似地增加。用葡萄糖培养24小时后，培养基中分泌的PANDER总浓度约为6 - 10 ng/ml（0.3 - 0.5 nmol/l）。L-葡萄糖未能刺激β-TC3细胞中PANDER的分泌。与无葡萄糖的对照相比，KCl刺激PANDER分泌2.1±0.1倍。L型Ca2+通道抑制剂硝苯地平完全阻断了葡萄糖或KCl诱导的胰岛素和PANDER分泌。在大鼠来源的INS-1细胞中，葡萄糖（20 mmol/l）刺激PANDER分泌4.4±0.9倍，而亮氨酸加谷氨酰胺与无葡萄糖的对照相比刺激4.4±0.7倍。在过表达PANDER的小鼠胰岛中，与基础状态（3 mmol/l葡萄糖）相比，葡萄糖（20 mmol/l）刺激PANDER分泌3.2±0.5倍（P<0.05）。α-TC3细胞也分泌PANDER，但不受葡萄糖刺激。半胱氨酸229或半胱氨酸91和229突变为丝氨酸（可能形成一个二硫键）以及PANDER的COOH末端或NH2末端截短均导致PANDER分泌失败，尽管这些突变或截短的PANDER在细胞内高度表达。总之，我们发现：1）PANDER由胰腺α细胞和β细胞分泌；2）葡萄糖在β细胞系和原代胰岛中剂量依赖性地刺激PANDER分泌，但在α细胞中不刺激；3）PANDER可能通过相同的调节机制与胰岛素共分泌；4）结构和构象对PANDER分泌至关重要。
