COL25A1 triggers and promotes Alzheimer's disease-like pathology in vivo

Collagen XXV alpha 1 (COL25A1) is a collagenous type II transmembrane protein purified from senile plaques of Alzheimer's disease (AD) brains. COL25A1 alleles have been associated with increased risk for AD in a Swedish population. COL25A1 is specifically expressed in neurons and binds to aggregated A beta in vitro. However, its contribution to the pathogenesis of AD and in vivo function are unknown. Here, we report that over-expression of COL25A1 in transgenic mice increases p35/p25 and beta-site APP-cleaving enzyme 1 (BACE1) levels, facilitates intracellular aggregation and extracellular matrix deposits of A beta, and causes synaptophysin loss and astrocyte activation. COL25A1 mice displayed reduced anxiety-like behavior in elevated plus maze and open field tests and significantly slower swimming speed in Morris water maze. In stable cell lines, motifs in noncollagenous domains of COL25A1 were important for the induction of BACE1 expression. These findings demonstrate that COL25A1 leads to AD-like pathology in vivo. Modulation of COL25A1 function may represent an alternative therapeutic intervention for AD.