The Transcriptionally Active Amyloid Precursor Protein (APP) Intracellular Domain Is Preferentially Produced from the 695 Isoform of APP in a β-Secretase-dependent Pathway
The Transcriptionally Active Amyloid Precursor Protein (APP) Intracellular Domain Is Preferentially Produced from the 695 Isoform of APP in a β-Secretase-dependent Pathway
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DOI：
10.1074/jbc.m110.141390
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发表时间：
2010-12-31
影响因子：
4.8
通讯作者：
Turner, Anthony J.
中科院分区：
文献类型：
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作者：
Belyaev, Nikolai D.;Kellett, Katherine A. B.;Turner, Anthony J.
β 和 γ 分泌酶对淀粉样前体蛋白 (APP) 进行淀粉样变加工，产生多种生物活性产物，包括淀粉样蛋白 -β (Aβ) 和 APP 胞内结构域 (AICD)。 AICD 调节多个神经元基因的转录，尤其是 A β 降解酶脑啡肽酶 (NEP)。 APP 存在多种选择性剪接异构体：APP(695)、APP(751) 和 APP(770)。我们检查了每种亚型是否有助于 AICD 的生成，从而上调 NEP 的表达。使用稳定表达每种 APP 亚型的 SH-SY5Y 神经元细胞，我们观察到只有 APP(695) 上调核 AICD 水平（9 倍）和 NEP 表达（6 倍）。 β-或γ-分泌酶抑制剂可以消除NEP表达的增加，但α-分泌酶抑制剂则不能。与 APP(751) 或 APP(770) 细胞相比，这与 APP(695) 细胞中 A beta(1-40) 和 A beta(1-42) 的显着增加相关。在 Neuro2a 细胞中观察到类似的现象，但在 HEK293 细胞中未观察到。与野生型APP(695)细胞相比，表达瑞典APP(695)突变体的SH-SY5Y细胞也显示Aβ水平和NEP表达增加。染色质免疫沉淀显示 AICD 与 APP(695)、Neuro2a 和 APP(Swe) 细胞中的 NEP 启动子相关，但与 APP(751) 和 APP(770) 细胞中的 NEP 启动子无关，其中 AICD 被组蛋白脱乙酰酶 1 (HDAC1) 取代。用 β 分泌酶抑制剂而非 α 分泌酶抑制剂处理 APP(695) 细胞后，NEP 启动子的 AICD 占据被 HDAC1 取代。在胆固醇耗尽的 APP(695) 细胞中，增加的 AICD 和 NEP 水平显着降低。总之，Aβ 和功能性 AICD 似乎是通过 APP(695) 上的 β 分泌酶作用优先合成的。
Amyloidogenic processing of the amyloid precursor protein (APP) by beta- and gamma-secretases generates several biologically active products, including amyloid-beta (A beta) and the APP intracellular domain (AICD). AICD regulates transcription of several neuronal genes, especially the A beta-degrading enzyme, neprilysin (NEP). APP exists in several alternatively spliced isoforms, APP(695), APP(751), and APP(770). We have examined whether each isoform can contribute to AICD generation and hence up-regulation of NEP expression. Using SH-SY5Y neuronal cells stably expressing each of the APP isoforms, we observed that only APP(695) up-regulated nuclear AICD levels (9-fold) and NEP expression (6-fold). Increased NEP expression was abolished by a beta- or gamma-secretase inhibitor but not an alpha-secretase inhibitor. This correlated with a marked increase in both A beta(1-40) and A beta(1-42) in APP(695) cells as compared with APP(751) or APP(770) cells. Similar phenomena were observed in Neuro2a but not HEK293 cells. SH-SY5Y cells expressing the Swedish mutant of APP(695) also showed an increase in A beta levels and NEP expression as compared with wild-type APP(695) cells. Chromatin immunoprecipitation revealed that AICD was associated with the NEP promoter in APP(695), Neuro2a, and APP(Swe) cells but not APP(751) nor APP(770) cells where AICD was replaced by histone deacetylase 1 (HDAC1). AICD occupancy of the NEP promoter was replaced by HDAC1 after treatment of the APP(695) cells with a beta- but not an alpha-secretase inhibitor. The increased AICD and NEP levels were significantly reduced in cholesterol-depleted APP(695) cells. In conclusion, A beta and functional AICD appear to be preferentially synthesized through beta-secretase action on APP(695).