Hong Young Gi, Roh Seyun, Paik Donggi, Jeong Sangyun
Department of Molecular Biology, Chonbuk National University, Jeonju 54896, Korea.
Department of Medicine, Division of Infectious Diseases and Immunology, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA.
Mol Cells. 2017 Jan;40(1):73-81. doi: 10.14348/molcells.2017.2294. Epub 2017 Jan 26.
The γ-secretase complex represents an evolutionarily conserved family of transmembrane aspartyl proteases that cleave numerous type-I membrane proteins, including the β-amyloid precursor protein (APP) and the receptor Notch. All known rare mutations in APP and the γ-secretase catalytic component, presenilin, which lead to increased amyloid βpeptide production, are responsible for early-onset familial Alzheimer's disease. β-amyloid protein precursor-like (APPL) is the ortholog of human APP. Here, we created Notch- and APPL-based reporter systems for monitoring of γ-secretase activity. Ectopic expression of the Notch- and APPL-based chimeric reporters in wings results in vein truncation phenotypes. Reporter-mediated vein truncation phenotypes are enhanced by the gain-of-function allele and suppressed by RNAi-mediated knockdown of . Furthermore, we find that apoptosis partly contributes to the vein truncation phenotypes of the APPL-based reporter, but not to the vein truncation phenotypes of the Notch-based reporter. Taken together, these results suggest that both reporter systems provide a powerful genetic tool to identify genes that modulate γ-secretase activity and/or APPL metabolism.
γ-分泌酶复合物代表了一个进化上保守的跨膜天冬氨酸蛋白酶家族，它能切割多种I型膜蛋白，包括β-淀粉样前体蛋白（APP）和Notch受体。APP和γ-分泌酶催化成分早老素中所有已知的罕见突变都会导致淀粉样β肽生成增加，这些突变是早发性家族性阿尔茨海默病的病因。β-淀粉样蛋白前体样蛋白（APPL）是人类APP的直系同源物。在此，我们创建了基于Notch和APPL的报告系统，用于监测γ-分泌酶活性。在翅膀中异位表达基于Notch和APPL的嵌合报告基因会导致翅脉截断表型。功能获得性等位基因会增强报告基因介导的翅脉截断表型，而RNA干扰介导的基因敲低会抑制该表型。此外，我们发现细胞凋亡部分导致了基于APPL的报告基因的翅脉截断表型，但对基于Notch的报告基因的翅脉截断表型没有影响。综上所述，这些结果表明这两种报告系统都提供了一种强大的遗传工具，用于鉴定调节γ-分泌酶活性和/或APPL代谢的基因。
