The metalloprotease inhibitor TIMP-3 regulates amyloid precursor protein and apolipoprotein E receptor proteolysis
The metalloprotease inhibitor TIMP-3 regulates amyloid precursor protein and apolipoprotein E receptor proteolysis
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DOI：
10.1523/jneurosci.3135-07.2007
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发表时间：
2007-10-03
影响因子：
5.3
通讯作者：
Rebeck, G. William
中科院分区：
文献类型：
--
作者：
Hoe, Hyang-Sook;Cooper, Matthew J.;Rebeck, G. William
细胞胆固醇水平改变淀粉样前体蛋白（APP）的加工，以产生A β。肝X受体（LXRs）的激活，一种调节胆固醇稳态的细胞机制，已被发现在体外和体内改变A β水平。为了鉴定LXR调控的基因，我们用LXR激动剂（TO-901317）处理人神经母细胞瘤细胞，并通过微阵列检测基因表达。正如预期的那样，TO-901317上调了几个胆固醇代谢基因，但它也降低了金属蛋白酶抑制剂TIMP-3的表达。我们使用实时PCR和通过测量胶质细胞、SY5Y细胞和COS 7细胞中的TIMP-3蛋白证实了这一发现。TIMP-3是金属蛋白酶抑制剂家族的成员，并且阻断A去整合素和金属蛋白酶-10（ADAM-10）和ADAM-17（两种APP α-分泌酶）。我们发现TIMP-3抑制APP和载脂蛋白E（apoE）受体ApoER 2的α-分泌酶裂解。TIMP-3降低ADAM-10、APP和ApoER 2的表面水平。这些变化伴随着APP β-C-末端片段和A β产生的增加。这些数据表明，TIMP-3优先路由APP和ApoER 2远离细胞表面和α-分泌酶裂解，并鼓励内吞作用和β-分泌酶裂解。在体内，TO-901317降低了脑TIMP-3水平。TIMP-3蛋白水平在人类阿尔茨海默病（AD）脑和APP转基因小鼠中增加，表明AD中TIMP-3水平增加可能导致A β水平升高。
Cellular cholesterol levels alter the processing of the amyloid precursor protein ( APP) to produce A beta. Activation of liver X receptors ( LXRs), one cellular mechanism to regulate cholesterol homeostasis, has been found to alter A beta levels in vitro and in vivo. To identify genes regulated by LXR, we treated human neuroblastoma cells with an LXR agonist ( TO-901317) and examined gene expression by microarray. As expected, TO-901317 upregulated several cholesterol metabolism genes, but it also decreased expression of a metalloprotease inhibitor, TIMP-3. We confirmed this finding using real-time PCR and by measuring TIMP-3 protein in glia, SY5Y cells, and COS7 cells. TIMP-3 is a member of a family of metalloproteinase inhibitors and blocks A disintegrin and metalloproteinase-10 ( ADAM-10) and ADAM-17, two APP alpha-secretases. We found that TIMP-3 inhibited alpha-secretase cleavage of APP and an apolipoprotein E ( apoE) receptor, ApoER2. TIMP-3 decreased surface levels of ADAM-10, APP, and ApoER2. These changes were accompanied by increased APP beta-C-terminal fragment and A beta production. These data suggest that TIMP-3 preferentially routes APP and ApoER2 away from the cell surface and alpha-secretase cleavage and encourages endocytosis and beta-secretase cleavage. In vivo, TO-901317 decreased brain TIMP-3 levels. TIMP-3 protein levels were increased in human Alzheimer's disease ( AD) brain and in APP transgenic mice, suggesting that increased levels of TIMP-3 in AD may contribute to higher levels of A beta.