Dissection of amyloid-β precursor protein-dependent transcriptional transactivation
Dissection of amyloid-β precursor protein-dependent transcriptional transactivation
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DOI：
10.1074/jbc.m402248200
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发表时间：
2004-06-04
影响因子：
4.8
通讯作者：
Südhof, TC
中科院分区：
文献类型：
--
作者：
Cao, XW;Südhof, TC
淀粉样β前体蛋白(APP)与接头蛋白Fe65和组蛋白乙酰转移酶Tip60形成转录活性复合体，但APP和Fe65介导的转录激活机制尚不清楚。APP被类似于Notch的伽马分泌酶切割，其胞内结构域通过与核转录因子相互作用来激活转录。为了测试APP胞内域(AICD)是否具有类似的功能，我们研究了APP和Fe65如何反式激活Tip60的Gal4融合蛋白。与Notch范式一致，我们观察到APP的伽马切割和Fe65的核转位是反式激活所必需的。然而，令人惊讶的是，我们发现AICD的核转位可能是可有可无的，只有膜拴AICD(即连接到跨膜区的AICD)而不是游离的AICD(即可溶性AICD)才是有效的转录反式激活因子。膜拴系的AICD招募Fe65，并介导结合的Fe65的激活，然后结合Fe65与AICD一起通过伽马切割释放用于核转位。我们的数据表明，APP和Notch的转录反式激活可能涉及不同的机制；而Notch胞内域直接在细胞核中发挥作用，而AICD通过激活Fe65间接作用。
Amyloid-beta precursor protein (APP) forms a transcriptionally active complex with the adaptor protein Fe65 and the histone acetyltransferase Tip60, but the mechanism of transcriptional activation that is mediated by APP and Fe65 remains unclear. APP is cleaved by gamma-secretase similar to Notch, whose intracellular domain activates transcription by interacting with nuclear transcription factors. To test whether the APP intracellular domain (AICD) functions analogously, we investigated how APP and Fe65 transactivate a Gal4 fusion protein of Tip60. Consistent with the Notch paradigm, we observe that gamma-cleavage of APP and nuclear translocation of Fe65 are required for transactivation. Surprisingly, however, we find that nuclear translocation of the AICD may be dispensable and that only membrane-tethered AICD (i.e. AICD coupled to a transmembrane region) and not free AICD (i.e. soluble AICD) is a potent transactivator of transcription. Membrane-tethered AICD recruits Fe65 and mediates the activation of bound Fe65 that is then released for nuclear translocation by gamma-cleavage together with the AICD. Our data suggest that transcriptional transactivation by APP and Notch may involve distinct mechanisms; whereas the Notch intracellular domain directly functions in the nucleus, the AICD acts indirectly by activating Fe65.