Expression of the Anti-amyloidogenic Secretase ADAM10 Is Suppressed by Its 5′-Untranslated Region
Expression of the Anti-amyloidogenic Secretase ADAM10 Is Suppressed by Its 5′-Untranslated Region
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DOI：
10.1074/jbc.m110.110742
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发表时间：
2010-05-21
影响因子：
4.8
通讯作者：
Haass, Christian
中科院分区：
文献类型：
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作者：
Lammich, Sven;Buell, Dominik;Haass, Christian
淀粉样前体蛋白由α-分泌酶进行蛋白质分解处理，防止淀粉样β-肽(Aβ)的形成，Aβ是阿尔茨海默病(AD)患者大脑中淀粉样斑块的主要成分。阿尔法分泌酶活性在阿尔茨海默病中降低，在阿尔茨海默病动物模型中，阿尔法分泌酶ADAM10(一种去整合素和金属蛋白酶10)的过度表达可以防止淀粉样蛋白的病理改变。ADAM10有一个444个核苷酸长、富含GC的5‘-非翻译区(5’-UTR)，带有两个上游开放阅读框。由于在许多受翻译调控机制调控的基因的转录产物中发现了类似的5‘-UTRs的性质，我们询问ADAM10的表达是否受其5’-UTRs的翻译调控。我们证明了ADAM10的5‘-UTR抑制了ADAM10的翻译速率。在没有5‘-UTR的情况下，我们观察到HEK293细胞中ADAM10蛋白水平显著增加，而mRNA水平没有变化。此外，在体外转录/翻译实验中，ADAM10的5‘-UTR抑制了荧光素酶报告基因的翻译。在HEK293细胞中连续删除ADAM10 5‘-UTR的前半部分，发现ADAM10蛋白的表达显著增加，表明这部分5’-UTR含有翻译抑制元件。此外，我们在HEK293细胞的条件培养液中检测到α-分泌酶活性增强，从而降低了Aβ水平，该细胞同时表达淀粉样前体蛋白和缺少5‘-UTR-ADAM10缺失结构的5’-UTR-ADAM10。因此，我们提供的证据表明，ADAM10的5‘-UTR可能在ADAM10表达的转录后调节中发挥重要作用，从而产生Aβ。
Proteolytic processing of the amyloid precursor protein by alpha-secretase prevents formation of the amyloid beta-peptide (A beta),which is the main constituent of amyloid plaques in brains of Alzheimer disease (AD) patients. alpha-Secretase activity is decreased in AD, and overexpression of the alpha-secretase ADAM10 (a disintegrin and metalloprotease 10) in an AD animal model prevents amyloid pathology. ADAM10 has a 444-nucleotide-long, very GC-rich 5'-untranslated region (5'-UTR) with two upstream open reading frames. Because similar properties of 5'-UTRs are found in transcripts of many genes, which are regulated by translational control mechanisms, we asked whether ADAM10 expression is translationally controlled by its 5'-UTR. We demonstrate that the 5'-UTR of ADAM10 represses the rate of ADAM10 translation. In the absence of the 5'-UTR, we observed a significant increase of ADAM10 protein levels in HEK293 cells, whereas mRNA levels were not changed. Moreover, the 5'-UTR of ADAM10 inhibits translation of a luciferase reporter in an in vitro transcription/translation assay. Successive deletion of the first half of the ADAM10 5'-UTR revealed a striking increase in ADAM10 protein expression in HEK293 cells, suggesting that this part of the 5'-UTR contains inhibitory elements for translation. Moreover, we detect an enhanced alpha-secretase activity and consequently reduced A beta levels in the conditioned medium of HEK293 cells expressing both amyloid precursor protein and a 5'-UTR-ADAM10 deletion construct lacking the first half of the 5'-UTR. Thus, we provide evidence that the 5'-UTR of ADAM10 may have an important role for post-transcriptional regulation of ADAM10 expression and consequently A beta production.