The amyloid precursor protein of Alzheimer disease is expressed as a 130 kDa polypeptide in various cultured cell types

Abstract

The vascular and parenchymal amyloid deposits in Alzheimer disease (AD), normal aging and Down syndrome are mainly composed of a 4 kDa polypeptide (A4), which derives from a larger precursor protein (APP). There is evidence that APP is a transmembrane glycoprotein present in most tissues, but the characteristics of APP in intact cells are not yet known. In order to investigate this issue, we examined the immunoreactivity of fibroblasts of human and nonhuman cell lines with antisera raised to synthetic peptides corresponding to A4 and to two other domains of the APP. All three antisera recognized a 130 kDa polypeptide (APP-130) in immunoblots from all cell lines. In fibroblasts, an additional polypeptide of 228 kDa (APP-228) was recognized by the antiserum to A4. In immunoblots of two dimensional gels, APP-130 showed a pl of 6.2, while APP-228 failed to focus in the pH range of 4.7 7.0. Sequential extractions of cells with buffer and with Triton X-100 indicate that APP-130 is extractable with nonionic detergents at high ionic strength, whereas 228 kDa APP is a cystolic component. Immunofluorescence staining is consistent with an intracellular perinuclear and plasma membrane localization. It is concluded that APP-130 and APP-228 are two forms of the APP which result from extensive posttranslational modifications of a smaller original gene product. It is likely that APP undergoes similar posttranslational modifications in different cell types.

The Ubiquitin-Proteasome System and Molecular Chaperone Deregulation in Alzheimer’s Disease

“…A possible link between APP and AD emerged in the late 1980s [23][24][25][26]. The evidence for a pivotal genetic role of APP in the progression of AD pathology stemmed from the shared APs with Down's syndrome [27,28].…”

Role of amyloid precursor protein (APP): Study with antisense transfection of human neuroblastoma cells

“…APP,,, features an extra 19-amino acid adjacent to the KPI domain (Kitaguchi et al, 1988). Although APP is expressed in most tissues and is highly conserved among species (Tanzi et al, 1987;Goldgaber et al, 1987;Shivers et al, 1988;Autilio-Gambetti et al, 1988;Yamada et al, 1989), alternatively spliced forms are differentially expressed in distinct cell types (Manning et al, 1988;Tanaka et al, 1989;Kang and Muller-Hill, 1990;Golde et al, 1990).…”

Increased release of an amyloidogenic C‐terminal Alzheimer amyloid precursor protein fragment from stressed PC‐12 cells

“…based on APP,, ,(Ponte et al, 1988) or A4 sequences)] include 1) M ab 22Cll(Kang et al, 1987), 2), 3 ) N-77 (APP 95-1 10)(Autilio-Gambetti et al, 1988), 4) Alz-4 (APP 190-208), 5) Up 98[APP 281-294 (Arai et al, 1990)], 6) Anti-F4:2 (APP 319-334), 7) Anti-KPI [APP 319-334(Palmert et al, 1989)], 8) Up 86 (APP 357-375,Arai et al, 1990), 9) IAF-5 (APP 475-591), 10) Anti-5 (APP 500-648), 11) Antibeta AP1-17(Palmert et al, 1988)], 12) Angela [amyloid(Selkoe et al, 1986)], 13) Corina [amyloid(Selkoe et al, 1986)], 14a) Anti-B1 (A4 1-43), 14b) Yoshiko [A4 1-38,(Joachim et al, 1989)], 15a) anti-Cl [APP 732-751], and 1Sb)…”