Direct and selective elimination of specific prions and amyloids by 4,5-dianilinophthalimide and analogs

Abstract

Mechanisms to safely eliminate amyloids and preamyloid oligomers associated with many devastating diseases are urgently needed. Biophysical principles dictate that small molecules are unlikely to perturb large intermolecular protein-protein interfaces, let alone extraordinarily stable amyloid interfaces. Yet 4,5-dianilinophthalimide (DAPH-1) reverses A␤42 amyloidogenesis and neurotoxicity, which is associated with Alzheimer's disease. Here, we show that DAPH-1 and select derivatives are ineffective against several amyloidogenic proteins, including tau, ␣-synuclein, Ure2, and PrP, but antagonize the yeast prion protein, Sup35, in vitro and in vivo. This allowed us to exploit several powerful new tools created for studying the conformational transitions of Sup35 and decipher the mechanisms by which DAPH-1 and related compounds antagonize the prion state. During fibrillization, inhibitory DAPHs alter the folding of Sup35's amyloidogenic core, preventing amyloidogenic oligomerization and specific recognition events that nucleate prion assembly. Select DAPHs also are capable of attacking preformed amyloids. They remodel Sup35 prion-specific intermolecular interfaces to create morphologically altered aggregates with diminished infectivity and self-templating activity. Our studies provide mechanistic insights and reinvigorate hopes for small-molecule therapies that specifically disrupt intermolecular amyloid contacts.

Aromatic Small Molecules Remodel Toxic Soluble Oligomers of Amyloid β through Three Independent Pathways

“…prevent all possible intermolecular interactions. Studies of small molecule inhibitors of protein aggregation also support our findings because many such antagonists promote alternative, unstructured aggregates rather than preventing condensation of protein monomers (30,44,45).…”

“…Several previous reports suggest that aromatic small molecules can alter the aggregation pathway of freshly disaggregated A␤, yet many such experiments were conducted over long times or at high concentrations where A␤ matures structurally even in the absence of small molecules (30,38,44,45). Thus, we evaluated if the small molecules investigated in this work would rapidly accelerate aggregation of freshly disaggregated A␤ over a time interval (4 h) in which A␤ otherwise fails to aggregate when not agitated (12).…”

Prion-like disorders: blurring the divide between transmissibility and infectivity

“…Although several small-molecule antagonists of amyloidogenesis have been described (Crowe et al, 2009; Gestwicki et al, 2004;Wang et al, 2008), there are many issues surrounding delivery of the small molecules to the appropriate site, including their passage across the blood-brain barrier (Brunden et al, 2009). Furthermore, the conformational diversity of amyloid strains severely complicates the development of potential smallmolecule therapies.…”

Prion proteostasis

“…During this process, prion recognition elements within the N-terminal prion domain termed the 'Head' and 'Tail' are proposed to make homotypic intermolecular contacts. Thus, fibers are held together by an alternating sequence of 'Head-to-Head' and 'Tailto-Tail' interactions, which are separated by a central core comprised of intramolecular contacts [39][40][41] (Fig. 1A).…”

“…Unfortunately, in contrast to Sup35 and Rnq1, 37,51 little is known about the factors that associate with Ure2 prions in vivo. Within the framework of the 'Head-to-Head' and 'Tail-to-Tail' model of Sup35 prion structure [39][40][41] (Fig. 2A), Hsp104 need only break the 'Head-to-Head' or 'Tail-to-Tail' intermolecular contact to fragment prions.…”