Transthyretin oligomers induce calcium influx via voltage-gated calcium channels.
The deposition of transthyretin (TTR) amyloid in the PNS is a major pathological feature of familial amyloidotic polyneuropathy. The aim of the present study was to examine whether TTR could disrupt cytoplasmic Ca(2+) homeostasis and to determine the role of TTR aggregation in this process. The aggregation of amyloidogenic TTR was examined by solution turbidity, dynamic light scattering and atomic force microscopy. A nucleation-dependent polymerization process was observed in which TTR formed low molecular weight aggregates (oligomers < 100 nm in diameter) before the appearance of mature fibrils. TTR rapidly induced an increase in the concentration of intracellular Ca(2+) ([Ca(2+)](i)) when applied to SH-SY5Y human neuroblastoma cells. The greatest effect on [Ca(2+)](i) was induced by a preparation that contained the highest concentration of TTR oligomers. The TTR-induced increase in [Ca(2+)](i) was due to an influx of extracellular Ca(2+), mainly via L- and N-type voltage-gated calcium channels (VGCCs). These results suggest that increasing [Ca(2+)](i) via VGCCs may be an important early event which contributes to TTR-induced cytotoxicity, and that TTR oligomers, rather than mature fibrils, may be the major cytotoxic form of TTR.
Hou
Xu
X
Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria 3800, Australia.
Parkington
Helena C
HC
Coleman
Harold A
HA
Mechler
Adam
A
Martin
Lisandra L
LL
Aguilar
Marie-Isabel
MI
Small
David H
DH
D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D015220:Calcium Channels / Q000502:physiology*; D045744:Cell Line, Tumor; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D004791:Enzyme Inhibitors / Q000494:pharmacology; D045604:Extracellular Fluid / Q000187:drug effects / Q000378:metabolism; D016257:Fura-2 / Q000378:metabolism; D006801:Humans; D018625:Microscopy, Atomic Force / Q000379:methods; D009154:Mutation / Q000502:physiology; D009447:Neuroblastoma / Q000473:pathology; D011228:Prealbumin / Q000737:chemistry* / Q000502:physiology*; D020836:Protein Structure, Quaternary / Q000502:physiology; D019284:Thapsigargin / Q000494:pharmacology; D013997:Time Factors; D014162:Transfection / Q000379:methods
D002121:Calcium Channel Blockers; D015220:Calcium Channels; D004791:Enzyme Inhibitors; D011228:Prealbumin; D019284:Thapsigargin; D002118:Calcium; D016257:Fura-2