γ-secretase is a macromolecular complex that catalyzes intramembranous hydrolysis of over 100 membrane-bound substrates. The complex is composed of presenilin (PS1 or PS2), anterior pharynx defect-1(APH-1), nicastrin (NCT) and PEN-2 and early-onset, autosomal dominant forms of AD are caused by inheritance of mutations of PS. No mutations in genes encoding NCT, or PEN-2 have been identified to date that cause AD. In this regard, a large genetic meta-analysis of 4 cohorts consisting of more than 600 000 individuals identified a common missense variant, rs117618017 in the APH1B gene that results in a T27I mutation, as a novel genome-wide significant locus. In order to confirm the findings that rs117618017 is associated with risk of AD, we performed a genetic screen from deep whole genome sequencing of the large NIMH family-based AD dataset. In parallel, we sought to uncover potential molecular mechanism(s) by which APH-1B T27I might be associated with AD by generating stable HEK293 cell lines wherein endogenous APH-1A and APH-1B expression was silenced and into which either wild type APH-1B or the APH-1B T27I variant was stably expressed. We then tested the impact of expressing either wild type APH-1B or the APH-1B T27I variant on γ-secretase processing of human APP, the murine Notch derivative mNΔE, and human neuregulin-1 (NRG-1). We now report that we fail to confirm the association of rs1047552 with AD in our cohort and that cells expressing the APH-1B T27I variant show no discernable impact on the γ-secretase processing of established substrates compared with cells expressing wild-type APH-1B.

中文翻译：

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APH1B T27I变体在阿尔茨海默氏病中的作用的阴性证据。

γ-分泌酶是一种大分子复合物，可催化100多种膜结合底物的膜内水解。该复合物由早老素（PS1或PS2），咽前部缺损1（APH-1），尼卡斯特林（NCT）和PEN-2组成，AD的早期，常染色体显性形式是由PS突变的遗传引起的。迄今为止，尚未发现编码NCT或PEN-2的基因突变引起AD。在这方面，对由超过60万个人组成的4个队列进行的大规模遗传荟萃分析，确定了APH1B基因中一个常见的错义变体rs117618017，该基因会导致T27I突变，是一个全基因组范围内的重要新基因座。为了确认rs117618017与AD风险相关的发现，我们从大型的基于NIMH家族的AD数据集的深层全基因组测序中进行了遗传筛选。同时，我们试图通过产生稳定的HEK293细胞系来揭示APH-1B T27I与AD相关的潜在分子机制，其中内源性APH-1A和APH-1B表达被沉默，而野生型APH- 1B或APH-1B T27I变体被稳定表达。然后，我们测试了表达野生型APH-1B或APH-1B T27I变体对人APP，鼠Notch衍生物mNΔE和人神经调节蛋白1（NRG-1）的γ-分泌酶加工的影响。我们现在报告，我们未能证实队列中rs1047552与AD的关联，并且与表达野生型APH-1B的细胞相比，表达APH-1B T27I变体的细胞对已建立的底物的γ-分泌酶处理没有明显的影响。我们试图通过产生稳定的HEK293细胞系来揭示APH-1B T27I可能与AD相关的潜在分子机制，其中内源性APH-1A和APH-1B表达被沉默，而野生型APH-1B或APH-1B T27I变体稳定表达。然后，我们测试了表达野生型APH-1B或APH-1B T27I变体对人APP，鼠Notch衍生物mNΔE和人神经调节蛋白1（NRG-1）的γ-分泌酶加工的影响。我们现在报告，我们未能证实队列中rs1047552与AD的关联，并且与表达野生型APH-1B的细胞相比，表达APH-1B T27I变体的细胞对已建立的底物的γ-分泌酶处理没有明显的影响。我们试图通过产生稳定的HEK293细胞系来揭示APH-1B T27I可能与AD相关的潜在分子机制，其中内源性APH-1A和APH-1B表达被沉默，而野生型APH-1B或APH-1B T27I变体稳定表达。然后，我们测试了表达野生型APH-1B或APH-1B T27I变体对人APP，鼠Notch衍生物mNΔE和人神经调节蛋白1（NRG-1）的γ-分泌酶加工的影响。我们现在报告，我们未能证实我们的队列中rs1047552与AD的关联，并且与表达野生型APH-1B的细胞相比，表达APH-1B T27I变体的细胞对已建立的底物的γ-分泌酶处理没有明显的影响。