Smith R D
Department of Clinical Biochemistry, Addenbrooke's Hospital, Cambridge, U.K.
Cell Biol Int. 1994 Jul;18(7):737-45. doi: 10.1006/cbir.1994.1103.
Like RIE-1 cells, two of the IEC series of rat intestinal epithelial cell lines were found to express functional angiotensin receptors. As in RIE-1 cells, treatment of IEC-6 or IEC-18 cells with angiotensin II (AII) activated phosphatidylinositol-4,5-bisphosphate (PIP2) hydrolysis although (in contrast to RIE-1 cells) the magnitude of AII-induced PIP2 hydrolysis was small and not associated with a mitogenic response in either IEC cell line. In terms of their other functional responses to AII (activation of protein kinase C (PKC) and a small elevation of cyclic AMP), IEC-6 cells are otherwise similar to RIE-1 cells whereas IEC-18 cells exhibit some phenotypic differences to the other two cell types. Thus, whereas IEC-6 and RIE-1 cells each express the AT1 subtype of angiotensin receptor, the higher affinity receptors on IEC-18 cells are 'atypical', being insensitive to both AT1- and AT2-specific angiotensin receptor antagonists. Furthermore, in contrast to its effects in IEC-6 and RIE-1 cells, AII neither activates PKC nor modulates cyclic AMP levels in IEC-18 cells. Whereas IEC-18 cells express the myristoylated alanine-rich C-kinase substrate (MARCKS), immunoreactive MARCKS was not detected in IEC-6 or RIE-1 cells.
与RIE-1细胞一样，在大鼠肠上皮细胞系的IEC系列中，发现有两种细胞系表达功能性血管紧张素受体。与RIE-1细胞一样，用血管紧张素II（AII）处理IEC-6或IEC-18细胞会激活磷脂酰肌醇-4,5-二磷酸（PIP2）水解，不过（与RIE-1细胞不同），AII诱导的PIP2水解程度较小，且在这两种IEC细胞系中均未观察到有丝分裂反应。就它们对AII的其他功能反应（蛋白激酶C（PKC）的激活和环磷酸腺苷（cAMP）的小幅升高）而言，IEC-6细胞与RIE-1细胞相似，而IEC-18细胞与其他两种细胞类型存在一些表型差异。因此，IEC-6和RIE-1细胞均表达血管紧张素受体的AT1亚型，而IEC-18细胞上亲和力较高的受体是“非典型的”，对AT1和AT2特异性血管紧张素受体拮抗剂均不敏感。此外，与它在IEC-6和RIE-1细胞中的作用相反，AII在IEC-18细胞中既不激活PKC也不调节cAMP水平。IEC-18细胞表达肉豆蔻酰化富含丙氨酸的C激酶底物（MARCKS），而在IEC-6或RIE-1细胞中未检测到免疫反应性MARCKS。
