Enzymes of physiological amyloidogenesis control pathological amyloid toxicity.

Physiological amyloidogenesis drives the formation of functional amyloids involved in various biochemical pathways. We recently showed that the RNA tailing and decay machinery controls the maturation of intracellular amyloid-like aggregates. This raises the question of whether enzymes that participate in the maturation of physiological amyloids are involved in pathological amyloidogenesis implicated in human proteopathies. Using Caenorhabditis elegans and mouse models of pathological amyloids, we show that manipulating the RNA tailing-decay axis alters the toxicity of β-amyloid and α-synuclein involved in Alzheimer's and Parkinson's diseases, respectively. The RNA tailing enzymes TENT4b and TENT2 protect against β-amyloid- and α-synuclein-induced toxicity by facilitating the formation of nontoxic amyloidogenic assemblies. In contrast, the RNA exonuclease Exosc10 potentiates pathological amyloid toxicity. Remarkably, Exosc10 depletion prevents cognitive decline and restores memory in two different mouse models of β-amyloid neurotoxicity. Taken together, these results suggest that pathways of physiological amyloidogenesis participate in pathological amyloid etiology.