Studies on the betacellulin receptor in pancreatic AR42J cells
Studies on the betacellulin receptor in pancreatic AR42J cells
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DOI：
10.1007/s001250050959
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发表时间：
1998-06-01
期刊：
影响因子：
8.2
通讯作者：
Kojima, I
中科院分区：
文献类型：
--
作者：
Ishiyama, N;Kanzaki, M;Kojima, I
β细胞素是表皮生长因子家族的成员，并将胰腺AR 42 J细胞转化为胰岛素产生细胞。进行本研究以鉴定AR 42J细胞中β细胞素的受体。AR 42 J细胞表达两类放射性碘标记β细胞素的结合位点，Kd值为4.6 × 10（-11）mol/l和3.0 × 10（-10）mol/l。未标记的β细胞素以剂量依赖性方式抑制[I-125] β细胞素的结合，但表皮生长因子的有效性比β细胞素低50倍。亲和交联显示分子量约为180 KDa的[I-125] β纤维素结合蛋白。当该蛋白质与抗表皮生长因子受体ErbB-1、ErbB-2、ErbB-3或ErbB-4的抗体免疫沉淀时，它仅被抗ErbB-1抗体免疫沉淀。当[I-125] β细胞素标记的蛋白质与四种ErbB抗体的组合免疫沉淀，然后未沉淀的蛋白质与抗磷酸酪氨酸抗体免疫沉淀时，观察到190 KDa的蛋白质。Betacellulin诱导ErbB-1、ErbB-2和ErbB-4的酪氨酸磷酸化。最后，虽然100 pmol/l β细胞素在激活素A存在下将所有AR 42 J转化为胰岛素产生细胞，但10 nmol/l表皮生长因子仅诱导约30%的细胞分化。较高浓度的表皮生长因子效果较差。Neu分化因子在表皮生长因子存在或不存在下均无效。这些结果表明，β细胞素结合ErbB-1和可能的另一种蛋白质的分子量为190 KDa。后者β细胞素结合蛋白可能参与β细胞素的分化诱导活性。
Betacellulin is a member of the epidermal growth factor family and converts pancreatic AR42J cells into insulin-producing cells. This study was conducted to characterise the receptor for betacellulin in AR42J cells. AR42J cells expressed two classes of binding sites for radioactive iodine labelled betacellulin, with Kd values of 4.6 x 10(-11) mol/l and 3.0 x 10(-10) mol/l. The binding of [I-125]betacellulin was inhibited by unlabelled betacellulin in a dose-dependent manner, but epidermal growth factor was 50 fold less effective than betacellulin. Affinity cross-linking showed a [I-125]betacellulin-binding protein with a molecular weight of approximately 180 KDa. When this protein was immunoprecipitated with antibody against epidermal growth factor receptors ErbB-1, ErbB-2, ErbB-3 or ErbB-4, it was immunoprecipitated only by the anti-ErbB-1 antibody. When the [I-125]betacellulin-labelled proteins were immunoprecipitated with a combination of the four ErbB antibodies, and the unprecipitated proteins were then immunoprecipitated with anti-phosphotyrosine antibody, a 190 KDa protein was observed. Betacellulin induced the tyrosine phosphorylation of ErbB-1, ErbB-2 and ErbB-4. Finally, while 100 pmol/l betacellulin converted all of the AR42J into insulin-producing cells in the presence of activin A, 10 nmol/l epidermal growth factor induced differentiation in only about 30% of the cells. Higher concentrations of epidermal growth factor were less effective. Neu differentiation factor in the presence or absence of epidermal growth factor was ineffective. These results indicate that betacellulin binds to ErbB-1 and possibly another protein with a molecular weight of 190 KDa. The latter betacellulin-binding protein may be involved in the differentiation-inducing activity of betacellulin.