In Alzheimer disease (AD), amyloid β peptide (Aβ) accumulates in plaques in the brain. Receptor for advanced glycation end products (RAGE) mediates Aβ-induced perturbations in cerebral vessels, neurons, and microglia in AD. Here, we identified a high-affinity RAGE-specific inhibitor (FPS-ZM1) that blocked Aβ binding to the V domain of RAGE and inhibited Aβ40-and Aβ42-induced cellular stress in RAGE-expressing cells in vitro and in the mouse brain in vivo. FPS-ZM1 was nontoxic to mice and readily crossed the blood-brain barrier (BBB). In aged APP sw/0 mice overexpressing human Aβ-precursor protein, a transgenic mouse model of AD with established Aβ pathology, FPS-ZM1 inhibited RAGE-mediated influx of circulating Aβ40 and Aβ42 into the brain. In brain, FPS-ZM1 bound exclusively to RAGE, which inhibited β-secretase activity and Aβ production and suppressed microglia activation and the neuroinflammatory response. Blockade of RAGE actions at the BBB and in the brain reduced Aβ40 and Aβ42 levels in brain markedly and normalized cognitive performance and cerebral blood flow responses in aged APP sw/0 mice. Our data suggest that FPS-ZM1 is a potent multimodal RAGE blocker that effectively controls progression of Aβ-mediated brain disorder and that it may have the potential to be a disease-modifying agent for AD.

Low-density lipoprotein receptor-related protein-1 (LRP) on brain capillaries clears amyloid β-peptide (Aβ) from brain. Here, we show that soluble circulating LRP (sLRP) provides key endogenous peripheral 'sink' activity for Aβ in humans. Recombinant LRP cluster IV (LRP-IV) bound Aβ in plasma in mice and in Alzheimer's disease-affected humans with compromised sLRPmediated Aβ binding, and reduced Aβ-related pathology and dysfunction in a mouse model of Alzheimer mice, suggesting LRP-IV can effectively replace native sLRP and clear Aβ.LRP binds the Alzheimer's disease neurotoxin, Aβ, at the abluminal side of the blood-brain barrier (BBB), which initiates Aβ clearance from brain to blood via transcytosis across the BBB1 -4. In the liver, LRP mediates systemic clearance of Aβ5. β-secretase cleaves the Nterminus extracellular domain of LRP6, which releases soluble LRP (sLRP). sLRP normally circulates in plasma 7 .Two major binding domains of LRP, cluster II and cluster IV 8 , bind Aβ in vitro with high affinity: i.e., Aβ40 > Aβ42 (ref. 2). We hypothesized that LRP recombinant cluster IV (LRP-IV) retains its high-affinity binding for Aβ in vivo, and that this binding alters Aβ transport at the BBB, which is dominated by the cell-surface LRP1 -4 and the receptor for advanced glycation end-products (RAGE) 9 , resulting in Aβ efflux from the brain. We also hypothesized

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The G-protein coupled receptor (GPCR)-kinase interacting proteins 1 and 2 (GIT1 and GIT2) are scaffold proteins with ADP-ribosylating factor GTPase activity. GIT1 and GIT2 control numerous cellular functions and are highly expressed in neurons, endothelial cells and vascular smooth muscle cells (VSMC). GIT1 promotes dendritic spine formation, growth and motility in cultured neurons, but its role in brain in vivo is unknown. By using global GIT1 knockout mice (GIT1 KO), we show that deletion of GIT1 results in markedly reduced dendritic length and spine density in the hippocampus by 36.7 % (p < 0.0106*) and 35.1% (p< 0.0028*) respectively compared to WT controls. This correlated with their poor adaptation to new environments as shown by impaired performance on tasks dependent on learning. We also studied the effect of GIT1 gene deletion on brain microcirculation. In contrast to findings in systemic circulation, GIT1 KO mice had an intact blood-brain barrier and normal regional cerebral blood flow as determined with radiotracers. Thus, our data suggest that GIT1 plays an important role in brain in vivo by regulating spine density involved in synaptic plasticity that is required for processes involved in learning. KeywordsG-protein coupled receptor kinase interacting protein 1, GIT1; spine formation; cytoskeleton dynamics; brain morphology; blood brain barrier; BBB