CHARACTERIZATION OF ANGIOTENSIN-II RECEPTOR SUBTYPES IN PANCREATIC ACINAR AR42J CELLS
CHARACTERIZATION OF ANGIOTENSIN-II RECEPTOR SUBTYPES IN PANCREATIC ACINAR AR42J CELLS
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DOI：
10.1016/0196-9781(95)00044-k
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发表时间：
1995-01-01
期刊：
影响因子：
3
通讯作者：
TALLANT, EA
中科院分区：
文献类型：
--
作者：
CHAPPELL, MC;JACOBSEN, DW;TALLANT, EA
AR42J 腺泡细胞系被认为是评估外分泌胰腺血管紧张素系统功能的潜在细胞模型。结合研究表明，AR42J 细胞表达高亲和力血管紧张素 II 结合位点（K-d = 0.73 +/- 0.06 nM；B-max = 292 +/- 15 fmol/mg 蛋白，n = 3）。竞争研究表明，这些细胞与完整的胰腺类似，主要表达 AT(2) 受体亚型。 AT(2) 选择性拮抗剂 CGP 42112A、PD 123177 和 PD 123319 竞争大部分血管紧张素 II 结合。然而，10-15% 的血管紧张素 II 结合位点被 AT(1) 选择性拮抗剂 DuP 753（氯沙坦）竞争。用[I-125]血管紧张素II对这些结合位点进行亲和标记，然后在还原条件下进行SDS凝胶电泳，结果显示包含分子量为108,000 Da的单条带。与未标记的血管紧张素 II 或 AT(2) 拮抗剂（而非 AT(1) 拮抗剂）竞争会消除 108,000 Da 条带。在完整细胞中，使用 Fura-2 作为 Ca2+ 指示剂，血管紧张素 II 导致细胞内钙 (Ca2+) 快速增加。用 AT(1) 拮抗剂 DuP 753 预处理细胞可完全抑制血管紧张素 II 诱导的 Ca2+ 升高；然而，AT(2) 拮抗剂 CGP 42112A 和 PD 123177 无法有效阻止 Ca2+ 增加。这些结果证明该胰腺腺泡细胞系表达 AT(2) 和 AT(1) 血管紧张素 II 受体亚型。 AT(1) 受体与 Ca2+ 的动员相结合，这是其他组织中 AT(?)1 受体所共有的特征。
The AR42J acinar cell line was characterized as a potential cellular model to assess the functional aspects of an exocrine pancreatic angiotensin system. Binding studies revealed that the AR42J cells express high affinity angiotensin II binding sites (K-d = 0.73 +/- 0.06 nM; B-max = 292 +/- 15 fmol/mg protein, n = 3). Competition studies established that these cells, similar to the intact pancreas, express predominantly the AT(2) receptor subtype. The AT(2)-selective antagonists CGP 42112A, PD 123177, and PD 123319 competed for the majority of angiotensin II binding. However, 10-15% of the angiotensin II binding sites were competed for by the AT(1)-selective antagonist DuP 753 (Losartan). Affinity labeling of these binding sites with [I-125]angiotensin II followed by SDS gel electrophoresis under reducing conditions revealed a single band comprising a molecular mass of 108,000 Da. Competition with unlabeled angiotensin II or the AT(2) antagonist, but not the AT(1) antagonist, abolished the 108,000-Da band. In intact cells, angiotensin II caused a rapid increase in intracellular calcium (Ca2+) using Fura-2 as a Ca2+ indicator. Pretreatment of the cells with the AT(1) antagonist DuP 753 completely inhibited the angiotensin II-induced rise in Ca2+; however, the AT(2) antagonists CGP 42112A and PD 123177 were ineffective in blocking the Ca2+ increase. These results demonstrate that this pancreatic acinar cell line expresses both AT(2) and AT(1) angiotensin II receptor subtypes. The AT(1) receptor is coupled to the mobilization of Ca2+-a characteristic shared by AT(?)1 receptors in other tissues.