The FASEB Journal • Research Communication The Psen1-L166P-knock-in mutation leads to amyloid deposition in human wild-type amyloid precursor protein YAC transgenic mice Ruben Vidal,* ,†,1 Neeraja Sammeta,* ,† Holly J. Garringer,* ,† Kumar Sambamurti, ‡ Leticia Miravalle,* ,† Bruce T. Lamb, § and Bernardino Ghetti* ,† *Department of Pathology and Laboratory Medicine and † Indiana Alzheimer Disease Center, Indiana University School of Medicine, Indianapolis, Indiana, USA; ‡ Department of Neuroscience, Medical University of South Carolina, Charleston, South Carolina, USA; and § Department of Neurosciences, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, Ohio, USA ABSTRACT Genetically engineered mice have been generated to model cerebral -amyloidosis, one of the hallmarks of Alzheimer disease (AD) pathology, based on the overexpression of a mutated cDNA of the amyloid- precursor protein (APP) or by knock-in of the murine App gene alone or with presenilin1 muta- tions. Here we describe the generation and initial characterization of a new mouse line based on the presence of 2 copies of the human genomic region encoding the wild-type APP and the L166P presenilin 1 mutation. At 6 mo of age, double-mutant mice de- velop amyloid pathology, with signs of neuritic dystro- phy, intracellular A accumulation, and glial inflamma- tion, an increase in APP C-terminal fragments, and an 8 times increase in A42 levels with a 40% decrease in A40 levels, leading to a significant increase (14 times) of A42/A40 ratios, with minimal effects on preseni- lin or the Notch1 pathway in the brain. We conclude that in mice, neither mutations in APP nor overexpres- sion of an APP isoform are a prerequisite for A pathology. This model will allow the study of AD pathogenesis and testing of therapeutic strategies in a more relevant environment without experimental artifacts due to the overexpression of a single-mutant APP isoform using exogenous promoters.—Vidal, R., Sammeta, N., Garringer, H. J., Sambamurti, K., Mi- ravalle, L., Lamb B. T., Ghetti, B. The Psen1-L166P- knock-in mutation leads to amyloid deposition in human wild-type amyloid precursor protein YAC trans- genic mice. FASEB J. 26, 2899 –2910 (2012). www.fasebj. org Key Words: presenilin  APP processing  animal model A hallmark of Alzheimer disease (AD) pathology is the accumulation in brain parenchyma and in vessel walls of the insoluble 4-kDa amyloid- (A) peptide and the intracellular accumulation of neurofibrillary tangles (NFTs) composed of tau paired helical fila- ments (PHFs) (1). A is a 40/42-43-aa peptide gen- erated by the successive proteolysis of the amyloid- precursor protein (APP) by the -site APP-cleaving enzyme 1 (BACE1) and the -secretase complex, whereas cleavage by -secretase (ADAM, a disintegrin and metalloproteinase) and -secretase prevents A generation (1–3). After - or -cleavage, the carboxyl- terminal fragments (CTFs) of APP known as CTF and CTF, respectively, remain membrane associated and are further cleaved by -secretase. The -secretase complex is a heterotetrameric aspartyl membrane- bound protease complex comprising 4 interacting mol- ecules: presenilin (PSEN or PS), nicastrin, anterior pharynx defective 1 (APH1), and PS enhancer 2 (Pen2) (1, 4, 5). In addition to APP, this complex interacts with a number of different substrates, including Notch, thus participating in a wide range of cellular functions (1, 6). More than 30 mutations in APP and 200 in the presenilin genes have been found to cause early- onset familial AD (FAD; http://www.molgen.ua. ac.be/ADMutations). The identification of genetic de- fects in APP, PSEN1, and PSEN2 has allowed a better understanding of the molecular mechanisms involved in the processing of APP and the generation of A peptides, as well as the development of animal models. Murine models based on gene targeting or transgenic expression of mutant forms of APP, PSEN1, and PSEN2 have proven valuable for the study of different 1 Correspondence: Department of Pathology and Labora- tory Medicine, Indiana University School of Medicine, 635 Barnhill Dr. MSB A136, Indianapolis, IN 46202, USA. E-mail: rvidal@iupui.edu doi: 10.1096/fj.12-205542 Abbreviations: A, amyloid-;APP, amyloid- precursor protein; Ab, antibody; AD, Alzheimer disease; APH1, anterior pharynx defective 1; BACE1, -site APP-cleaving enzyme 1; CAA, cerebral amyloid angiopathy; CTF, carboxyl-terminal fragment; ES, embryonic stem; FAD, familial Alzheimer dis- ease; FSH, follicle-stimulating hormone; GFAP, glial fibrillary acidic protein; LH, luteinizing hormone; NFT, neurofibrillary tangle; NICD, Notch intracellular domain; NTF, N-terminal fragment; Pen2, PS enhancer 2; PHF, paired helical filament; PS, presenilin; PSEN, presenilin; Th-S, thioflavin S; WT, wild-type; YAC, yeast artificial chromosome 2899 0892-6638/12/0026-2899 © FASEB