Small molecule NPT-440-1 inhibits ionic flux through Aß1-42 pores: Implications for Alzheimer's disease therapeutics.

ABSTRACT

Increased levels of soluble amyloid-beta (Aß) oligomers are suspected to underlie Alzheimer's disease (AD) pathophysiology. These oligomers have been shown to form multi-subunit Aß pores in bilayers and induce uncontrolled, neurotoxic, ion flux, particularly calcium ions, across cellular membranes that might underlie cognitive impairment in AD. Small molecule interventions that modulate pore activity could effectively prevent or ameliorate their toxic activity. Here we examined the efficacy of a small molecule, NPT-440-1, on modulating amyloid pore permeability. Co-incubation of B103 rat neuronal cells with NPT-440-1 and Aß1-42 prevented calcium influx. In purified lipid bilayers, we show that a 10-15min preincubation, prior to membrane introduction, was required to prevent conductance. Thioflavin-T and circular dichroism both suggested a reduction in Aß1-42 ß-sheet content during this incubation period. Combined with previous studies on site-specific amino acid substitutions, these results suggest that pharmacological modulation of Aß1-42 could prevent amyloid pore-mediated AD pathogenesis.