The effects of dietary restriction and aging on amyloid precursor protein and presenilin-1 mRNA and protein expression in rat brain Aleksandra N. Mladenovic Djordjevic, Milka Perovic, Kosara Smiljanic, Smilja Todorovic, Vesna Tesic, Sabera Ruzdijic and Selma Kanazir The objective of this study was to examine the effects of aging and long-term dietary restriction (DR) on the level of amyloid precursor protein (APP) and presenilin-1 (PS-1), proteins that are critically involved in Alzheimer’s disease. Changes in mRNA and protein expression were assessed by real-time PCR and western blot analysis during aging and long-term DR in the cortex and hippocampus of 6-, 12-, 18-, and 24-month-old rats. Prominent regional changes in expression were observed in response to aging and DR. Although the hippocampus displayed significant alterations in APP mRNA and protein expression and no significant changes in PS-1 expression, an opposite pattern was observed in the cortex. DR counteracted the age-related changes in APP mRNA expression in both structures of old animals. The observed DR-induced increase in mRNA levels in the hippocampus was accompanied by an increase in the level of full-length protein APP. These results indicate that although both structures are very sensitive to aging, a specific spatial pattern of changes in APP and PS-1 occurs during aging. Furthermore, these findings provide evidence that DR can affect APP and PS-1 expression in a manner consistent with its proposed ‘antiaging’ effect. NeuroReport 25:398–403  c 2014 Wolters Kluwer Health | Lippincott Williams & Wilkins. NeuroReport 2014, 25:398–403 Keywords: aging, amyloid precursor protein, cortex, dietary restriction, hippocampus, presenilin-1, rat Department of Neurobiology, Institute for Biological Research ‘Sinisa Stankovic’, University of Belgrade, Belgrade, Serbia Correspondence to Aleksandra N. Mladenovic Djordjevic, PhD, Department of Neurobiology, Institute for Biological Research ‘Sinisa Stankovic’, University of Belgrade, Bulevar Despota Stefana 142, 11000 Belgrade, Serbia Tel: + 381 11 2078337; fax: + 381 11 2761433; e-mail: anamikos@ibiss.bg.ac.rs Received 18 October 2013 accepted 18 November 2013 Introduction Increasing age is an established risk factor for many neurodegenerative disorders including Alzheimer’s dis- ease (AD). Mutations in genes that encode for amyloid precursor protein (APP) and presenilin-1 (PS-1) are linked to familial AD [1]. However, PS and APP proteins have many physiological functions (reviewed in Turner et al. [2]) and are also involved in the etiology of the much more common late-onset form of AD [3]. Full-length APP is a membrane-anchored protein that is rapidly metabolized through two mutually exclusive pathways, where series of cleavages by secretase result in the production of several peptides, including Ab (reviewed in Turner et al. [2]). APP and its fragments have important functions in neuroprotection, axonal transport, cholesterol metabolism, synaptic plasticity, learning, and memory (reviewed in Turner et al. [2]). Both APP and PS-1 display parallel quantitative changes throughout life, and the expression of PS-1 is spatially synchronized with the appearance of APP [4]. The unstable PS-1 holoprotein has a very short half-life and undergoes constitutive endoproteolysis into N-terminal and C-terminal fragments that form stable 1 : 1 heterodimers, the presumed biologically active form of PS-1. Together with several other proteins, PS-1 exhibits g-secretase activity toward different substrates, including APP (reviewed in Selkoe and Wolfe [5]). The role of PS-1 extends beyond its proteolytic activity. Namely, the presenilins have been shown to be involved in several biological processes, including neuro- genesis, synapse formation, and apoptosis [6]. A reduction in food intake, referred to as dietary restriction (DR), was shown to extend lifespan in many species and to delay the onset of several age-related diseases, such as neurodegenerative disorders (reviewed in Masoro [7]). One of the proposed mechanisms through which DR exerts its effects is alterations in gene expression [8]. Aging per se significantly changes the expression of genes involved in amyloid processing [9,10]. Alterations in APP gene transcription have been suggested to underlie the accumulation of Ab [11]. Subjecting mice to a DR regimen was observed to influence Ab generation and amyloid plaque deposition [12,13] even in older animals (13–14-month-old rats) [14]. An overlap in gene expression between normal aging and AD [15,16] could have important implications for further research given that changes that occur during normal aging increase the susceptibility to AD. In the present study, we examined the age-related changes in APP and 398 Gene expression, PCR, gene array, in situ hybridization histochemistry, mRNA 0959-4965  c 2014 Wolters Kluwer Health | Lippincott Williams & Wilkins DOI: 10.1097/WNR.0000000000000107 Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.