Liu L, Moesner P, Kovach N L, Bailey R, Hamilton A D, Sebti S M, Harlan J M
Division of Hematology, University of Washington, Seattle, Washington 98195, USA.
J Biol Chem. 1999 Nov 19;274(47):33334-40. doi: 10.1074/jbc.274.47.33334.
Integrin-dependent leukocyte adhesion is modulated by alterations in receptor affinity or by post-receptor events. Pretreatment of Jurkat T-cells with the 3-hydroxymethylglutaryl-coenzyme A reductase inhibitor, lovastatin, markedly reduced (IC(50) approximately 1-2 microM) alpha(4)beta(1)-dependent adhesion to fibronectin (FN) stimulated by phorbol 12-myristate 13-acetate (PMA) which modulates post-receptor events. In contrast, lovastatin did not inhibit Jurkat cell adhesion to FN induced by the beta(1) integrin-activating monoclonal antibody (mAb) 8A2, which directly modulates beta(1) integrin affinity. Similarly, pretreatment of U937 cells with lovastatin inhibited PMA-stimulated, but not mAb 8A2-stimulated, alpha(6)beta(1)-dependent leukocyte adhesion to laminin. The inhibition of lovastatin on PMA-stimulated leukocyte adhesion was not mediated by mitogen-activated protein kinase or phosphatidylinositol 3-kinase pathway. The inhibitory effect of lovastatin on PMA-stimulated leukocyte adhesion was reversed by co-incubation with geranylgeraniol, but not with farnesol, with concurrent reversal of the inhibition of protein prenylation as shown by protein RhoA geranylgeranylation. The selective inhibition of protein geranylgeranylation by the specific protein geranylgeranyltransferase-I inhibitor, GGTI-298, blocked PMA-stimulated leukocyte adhesion but not mAb 8A2-induced leukocyte adhesion. The protein farnesyltransferase inhibitor, FTI-277, had no effect on leukocyte adhesion induced by either stimulus. These results demonstrate that protein geranylgeranylation, but not farnesylation, is required for integrin-dependent post-receptor events in leukocyte adhesion.
整合素依赖性白细胞黏附可通过受体亲和力的改变或受体后事件进行调节。用3-羟基-3-甲基戊二酰辅酶A还原酶抑制剂洛伐他汀预处理Jurkat T细胞，可显著降低（IC50约为1 - 2 microM）佛波醇12-肉豆蔻酸酯13-乙酸酯（PMA）刺激的α4β1依赖性对纤连蛋白（FN）的黏附，PMA可调节受体后事件。相比之下，洛伐他汀不抑制β1整合素激活单克隆抗体（mAb）8A2诱导的Jurkat细胞对FN的黏附，该抗体直接调节β1整合素亲和力。同样，用洛伐他汀预处理U937细胞可抑制PMA刺激的，但不抑制mAb 8A2刺激的α6β1依赖性白细胞对层粘连蛋白的黏附。洛伐他汀对PMA刺激的白细胞黏附的抑制作用不是由丝裂原活化蛋白激酶或磷脂酰肌醇3-激酶途径介导的。洛伐他汀对PMA刺激的白细胞黏附的抑制作用可通过与香叶基香叶醇共同孵育而逆转，但与法尼基醇共同孵育则不能，同时如蛋白RhoA香叶基香叶酰化所示，蛋白异戊二烯化的抑制也得到逆转。特异性蛋白香叶基香叶基转移酶-I抑制剂GGTI-298对蛋白香叶基香叶酰化的选择性抑制可阻断PMA刺激的白细胞黏附，但不阻断mAb 8A2诱导的白细胞黏附。蛋白法尼基转移酶抑制剂FTI-277对两种刺激诱导的白细胞黏附均无影响。这些结果表明，在白细胞黏附的整合素依赖性受体后事件中，需要蛋白香叶基香叶酰化而非法尼基化。
