Epitope-specific antibody-induced cleavage of angiotensin-converting enzyme from the cell surface
Epitope-specific antibody-induced cleavage of angiotensin-converting enzyme from the cell surface
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DOI：
10.1042/0264-6021:3620585
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发表时间：
2002-03-15
影响因子：
4.1
通讯作者：
Danilov, SM
中科院分区：
文献类型：
--
作者：
Balyasnikova, IV;Karran, EH;Danilov, SM
血管紧张素转换酶(ACE；CD 143，EC 3.4.15.1)是一种1型完整的膜蛋白，也可以在一种未知的被称为血管紧张素转换酶分泌酶的酶(S)的作用下，以可溶性酶的形式释放到细胞外液(如血浆、精液和脑脊液)中，这一过程被称为“脱落”。利用表达血管紧张素转换酶基因的中国仓鼠卵巢细胞(CHO细胞)和人脐静脉内皮细胞，研究了抗血管紧张素转换酶N端区8个不同表位的单抗对血管紧张素转换酶(ACE)N端区8个不同表位的影响。抗体诱导的血管紧张素转换酶的脱落具有很强的表位特异性：大多数抗体使血管紧张素转换酶的脱落增加20-40%，单抗9B9和3A5分别增加270%和41010，而与单抗3G8的结合使血管紧张素转换酶的脱落减少36%。羟胺酸类金属蛋白酶抑制剂(batimastat，BB-94)抑制单抗诱导的血管紧张素转换酶脱落的效果是基础(结构性)血管紧张素转换酶释放的15倍。用BB-94处理CHO-ACE细胞可以更有效地阻止3，4-二氯异香豆素和碘乙酰胺诱导的抗体依赖性(但不是基础)ACE释放的增加。这些数据表明，与抗体诱导的脱落相比，基础状态下不同的分泌可能是导致ACE释放的原因。对40多种蛋白水解酶抑制剂的进一步实验表明，钙蛋白酶、呋喃和蛋白酶体可能参与了这一过程。
Angiotensin 1-converting enzyme (ACE; CD 143, EC 3.4.15. 1) is a type-1 integral membrane protein that can also be released into extracellular fluids (such as plasma, and seminal and cerebrospinal fluids) as a soluble enzyme following cleavage mediated by an unidentified protease(s), referred to as ACE secretase, in a process known as 'shedding'. The effects of monoclonal antibodies (mAbs) to eight different epitopes on the N-terminal domain of ACE on shedding was investigated using Chinese hamster ovary cells (CHO cells) expressing an ACE transgene and using human umbilical vein endothelial cells. Antibody-induced shedding of ACE was strongly epitope-specific: most of the antibodies increased the shedding by 20-40%, mAbs 9B9 and 3A5 increased the shedding by 270 and 41010 respectively, whereas binding of mAb 3G8 decreased ACE shedding by 36% The ACE released following mAb treatment lacked a hydrophobic transmembrane domain anchor, The antibody-induced shedding was completely inhibited at 4 degreesC and by zinc chelation using 1, 10-phenanthroline, suggesting involvement of a metalloprotease in this process. A hydroxamate-based metalloprotease inhibitor (batimastat, BB-94) was 15 times more efficacious in inhibiting mAb-induced ACE shedding than basal (constitutive) ACE release. Treatment of CHO-ACE cells with BB-94 more effectively prevented elevation in antibody-dependent (but not basal) ACE release induced by 3,4-dichloroisocoumarin and iodoacetamide. These data suggest that different secretases might be responsible for ACE release under basal compared with antibody-induced shedding. Further experiments with more than 40 protease inhibitors suggest that calpains, furin and the proteasome may participate in this process.