Cellular secretion and cytotoxicity of transthyretin mutant proteins underlie late-onset amyloidosis and neurodegeneration.

Cellular secretion and cytotoxicity of transthyretin mutant proteins underlie late-onset amyloidosis and neurodegeneration. Cell Mol Life Sci. 2019 Nov 14;: Authors: Ibrahim RB, Yeh SY, Lin KP, Ricardo F, Yu TY, Chan CC, Tsai JW, Liu YT Abstract Transthyretin amyloidosis (ATTR) is a progressive life-threatening disease characterized by the deposition of transthyretin (TTR) amyloid fibrils. Several pathogenic variants have been shown to destabilize TTR tetramers, leading to aggregation of misfolded TTR fibrils. However, factors that underlie the differential age of disease onset amongst amyloidogenic TTR variants remain elusive. Here, we examined the biological properties of various TTR mutations and found that the cellular secretory pattern of the wild-type (WT) TTR was similar to those of the late-onset mutant (Ala97Ser, p. Ala117Ser), stable mutant (Thr119Met, p. Thr139Met), early-onset mutant (Val30Met, p. Val50Met), but not in the unstable mutant (Asp18Gly, p. Asp38Gly). Cytotoxicity assays revealed their toxicities in the order of Val30Met > Ala97Ser > WT > Thr119Met in neuroblastoma cells. Surprisingly, while early-onset amyloidogenic TTR monomers (M-TTRs) are retained by the endoplasmic reticulum quality control (ERQC), late-onset amyloidogenic M-TTRs can be secreted extracellularly. Treatment of thapsigargin (Tg) to activate the unfolded protein response (UPR) alleviates Ala97Ser M-TTR secretion. Interest...
Source: Cellular and Molecular Life Sciences : CMLS - Category: Cytology Authors: Tags: Cell Mol Life Sci Source Type: research