The gamma secretase-generated carboxyl-terminal domain of the amyloid precursor protein induces apoptosis via Tip60 in H4 cells.
The gamma secretase-generated carboxyl-terminal domain of the amyloid precursor protein induces apoptosis via Tip60 in H4 cells.
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发表时间：
2002
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通讯作者：
A. Kinoshita;C. Whelan;O. Berezovska;B. Hyman
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作者：
A. Kinoshita;C. Whelan;O. Berezovska;B. Hyman
淀粉样蛋白前体蛋白（APP）是一种在神经元中高度表达的大糖蛋白，在其膜内区域被γ分泌酶裂解，生成淀粉样蛋白- β和游离羧基末端细胞内片段（APP- ct），该片段先前被认为与衔接蛋白Fe65和组蛋白乙酰转移酶Tip60相互作用。一种相同的γ分泌酶活性介导Notch的裂解，释放一个细胞内信号域并易位到细胞核。我们检测了异位表达的58个氨基酸的APP-CT片段（APP-C58）对人H4神经胶质瘤细胞的影响。我们通过共聚焦显微镜和荧光共振能量转移分析证明，APP-C58易位到核中，并与Tip60在核中形成复合物，不依赖于与Fe65的相互作用。APP-C58转染的H4细胞在48-72 h内凋亡，表现为核泡、末端脱氧核苷酸转移酶介导的dUTP镍端标记（TUNEL）染色和caspase抑制剂阻断。当APP-C58通过与一个强膜靶向法尼化结构域融合而阻止其核通路时，细胞凋亡被阻断。与野生型Tip60共转染后，app - c58诱导的细胞凋亡明显增强，而缺乏组蛋白乙酰转移酶活性的突变型Tip60诱导的细胞凋亡减少，提示Tip60介导app - ct诱导的细胞死亡。因此，γ分泌酶切割APP可能通过两种方式促进阿尔茨海默病相关的神经变性：淀粉样蛋白- β的释放和从膜结合的APP中释放生物活性羧基末端结构域。
The amyloid precursor protein (APP), a large glycoprotein highly expressed in neurons, is cleaved in its intramembranous domain by gamma secretase to generate amyloid-beta and a free carboxyl-terminal intracellular fragment (APP-CT), which has previously been suggested to interact with the adapter protein Fe65 and the histone acetyltransferase Tip60. An identical gamma secretase activity mediates cleavage of Notch, releasing an intracellular signaling domain that translocates to the nucleus. We examined the effect of an ectopically expressed 58-amino acid APP-CT fragment (APP-C58) on human H4 neuroglioma cells. We demonstrate by confocal microscopy and fluorescence resonance energy transfer analysis that APP-C58 translocates to the nucleus and forms a complex in the nucleus with the Tip60, independent of interactions with Fe65. APP-C58 transfected H4 cells undergo apoptosis within 48-72 h, marked by nuclear blebbing, terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) staining, and blockade by a caspase inhibitor. When nuclear access of APP-C58 is prevented by fusing with a strong membrane-targeting farnesylation domain, apoptosis is blocked. APP-C58-induced apoptosis was markedly enhanced by co-transfection with wild type Tip60 and decreased by mutant Tip60 lacking histone acetyltransferase activity, suggesting that Tip60 mediates APP-CT-induced cell death. Thus, gamma secretase cleavage of APP may contribute to Alzheimer's disease-related neurodegeneration in two ways: release of amyloid-beta and liberation of a bioactive carboxyl-terminal domain from membrane-bound APP.