Calmidazolium Chloride and Its Complex with Serum Albumin Prevent Huntingtin Exon1 Aggregation

Abstract

Huntington's disease (HD) is a genetic disorder caused by a CAG expansion mutation in Huntingtin gene leading to polyglutamine (polyQ) expansion in the N-terminus side of Huntingtin (Httex1) protein. Neurodegeneration in HD is linked to aggregates formed by Httex1 bearing an expanded polyQ. Initiation and elongation steps of Httex1 aggregation are potential target steps for the discovery of therapeutic molecules for HD, which is currently untreatable. Here we report Httex1 aggregation inhibition by calmidazolium chloride (CLC) by acting on the initial aggregation event. Because it is hydrophobic, CLC was adsorbed to the vial surface and could not sustain an inhibition effect for a longer duration. The use of bovine serum albumin (BSA) prevented CLC adsorption by forming a BSA-CLC complex. This complex showed improved Httex1 aggregation inhibition by interacting with the aggregation initiator, the NT₁₇ part of Httex1. Furthermore, biocompatible CLC-loaded BSA nanoparticles were made which reduced the polyQ aggregates in HD-150Q cells.

Keywords: Huntington’s disease; adsorption; calmidazolium chloride; polyglutamine aggregation; serum albumin.