Amyloid beta binding partners in the brain tissue of older adults.

INTRODUCTION: The mechanism linking extracellular amyloid beta (Aβ) with intraneuronal tau tangles, pathological hallmarks of Alzheimer's disease (AD), is not understood; it was tested in the current study through Aβ binding partners. METHODS: Data were from decedents of community-based clinical-pathological studies. Of 52 Aβ binding partners, suggested by non-human studies, levels of 34 together with total Aβ protein were quantified in the dorsolateral prefrontal cortex. Post mortem pathological assessment immunohistochemically quantified Aβ load and tau tangle density. RESULTS: The strongest mediations between Aβ and tau tangles were observed for Ras-related C3 botulinum toxin substrate 1 (RAC1) and sodium/potassium-transporting ATPase subunit alpha-3 (ATP1A3), which collectively mediated 10.1% of the association between Aβ and tau tangles. In contrast, Aβ mediated >70% of the associations of matrix proteins with tau tangles. DISCUSSION: Identification of Aβ binding partners that mediate the association between Aβ and tau tangles may provide new targets for AD treatment. HIGHLIGHTS: RAC1 linked Aβ with tau tangles. ATP1A3 linked Aβ with tau. RAC1 and ATP1A3 collectively mediated 10.1% of the association between Aβ and tau. Aβ mediated >70% of the associations of matrix proteins, such as APOE, with tau.