This research will be done primarily in Serbia at the Institute for Biological Research University of Belgrade (LMIC site) in collaboration with Selma Kanazir with the companion grant being R37AG023084, 9/15/2004 to 8/31/2014. We propose to extend aim 4 of the companion grant to study the effects of caloric dietary restriction (DR) on brain and systemic clearance of Alzheimer's disease (AD) neurotoxin amyloid ?-peptide (A?) and on cognitive functions using a transgenic model of AD-like cerebral ?-amyloidosis. The proposed research will significantly enhance the neuroscience research capacity at the LMIC site which is a major biomedical research institution in Serbia and the capabilities of both the LMIC collaborator and the next generation of Serbian researchers to study brain disorders. The LMIC site has experience in DR models. DR reduces A? pathology and improves behavior in mice with AD-like cerebral pathology, but the molecular and cellular mechanisms of this improvement remain elusive. The major goal of this proposal is to determine the effects of DR on (i) brain and systemic A? clearance mediated by the sterol response element binding protein 2 (SREBP2)/low density lipoprotein receptor related protein 1 (LRP1) and (ii) cognitive functions. LRP1-mediated A? clearance in the cerebrovascular system, blood and liver is the major mechanism for removal of A? toxin. SREBP2, a key gene regulating cholesterol metabolism, is a major transcriptional suppressor of LRP1. DR or 24 h fasting downregulates SREBP2 in the liver and brain and increases LRP1 expression as shown by Kanazir's pilot data. Our central hypothesis is that DR downregulates SREBP2 in brain vasculature and liver which in turn increases LRP1 activity promoting brain and systemic A? clearance thereby improving cognitive functions. We will study APPsw/0 mice on normal diet or DR (aim 1) and with forced SREBP2 expression induced by myocardin gene transfer to brain blood vessels (aim 2). APPsw/0 mice have been transferred to Belgrade in Nov 2010 to allow Kanazir to start her own colony. This is the first transgenic colony established at the Belgrade University. Members of the Kanazir group are versed with the proposed methods to be performed at the LMIC site and will continue to be trained by Zlokovic's group in new state-of-the art methods as needed. Prior to the FIRCA proposal, Zlokovic visited Kanazir and members of her team in Belgrade during January and June 2010, and Kanazir spent 4 months in Zlokovic's former lab in Rochester from Aug 4 to Dec 7, 2010. Kanazir provided creative and important scientific input to the research plan of the FIRCA. This proposal will contribute to building much needed research capacity at the University of Belgrade by enabling the LMIC site to expand research in brain disorders, to introduce new technological approaches, and develop existing research facilities. It will enable short exchange visits of junior researchers between Belgrade and Los Angeles and help improve the productivity and build enthusiasm among young Serbian researchers. We expect the proposal will establish a long-standing collaboration between the Zlokovic group and the LMIC site/PI's group.