Effect of Nitric Oxide in Amyloid Fibril Formation on Transthyretin-Related Amyloidosis

Abstract

Although oxidative stress is said to play an important role in the amyloid formation mechanism in several types of amyloidosis, few details about this role have been described. Amyloid is commonly deposited around the vessels that are the primary site of action of nitric oxide generated from endothelial cells and smooth muscle cells, so nitric oxide may be also implicated in amyloid formation. For this study, we examined the in vitro effect of S-nitrosylation on amyloid formation induced by wild-type transthyretin, a precursor protein of senile systemic amyloidosis, and amyloidogenic transthyretin V30M, a precursor protein of amyloid deposition in familial amyloidotic polyneuropathy. S-Nitrosylation of amyloidogenic transthyretin V30M via the cysteine at position 10 was 2 times more extensive than that of wild-type transthyretin in a nitric oxide-generating solution. Both wild-type transthyretin and amyloidogenic transthyretin V30M formed amyloid fibrils under acidic conditions, and S-nitrosylated transthyretins exhibited higher amyloidogenicity than did unmodified transthyretins. Moreover, S-nitrosylated amyloidogenic transthyretin V30M formed more fibrils than did S-nitrosylated wild-type transthyretin. Structural studies revealed that S-nitrosylation of amyloidogenic transthyretin V30M induced a change in its conformation, as well as instability of the tetramer conformation. These results suggest that the nitric oxide-mediated modification of transthyretin, especially variant transthyretin, may play an important role in amyloid formation in senile systemic amyloidosis and familial amyloidotic polyneuropathy.

Loss of functional albumin triggers acceleration of transthyretin amyloid fibril formation in familial amyloidotic polyneuropathy

“…15,[42][43][44][45] We previously reported evidence of oxidative stress in deposits of amyloid in tissues of patients with FAP. 45 Our more recent in vitro studies also showed that nitric oxide-mediated modification of TTR may have an important role in amyloid formation.…”

“…15,22 Albumin was isolated from serum samples from healthy volunteers by means of ion-exchange chromatography. Albumin-containing bound fatty acids (FA-albumin) was donated by the Chemo-Sero-Therapeutic Research Institute (Kaketsuken, Kumamoto, Japan) and was isolated by using a Sephadex G-25 column (Nihon Waters K.K., Tokyo, Japan).…”

“…TTR amyloid was prepared in 20 mM sodium acetate and 100 mM NaCl at pH 3.0 in an Eppendorf tube by incubation at 371C for 5 days. 15 …”

“…The resultant stationary solutions were incubated at 371C for 5 days in the dark. 15 Albumin inhibits TTR amyloid formation T Kugimiya et al ELISA To quantify TTR amyloid fibrils in vitro, the peroxidase-antiperoxidase method for sandwich ELISA was used. PBS containing 0.05% Tween 20 was used as a buffer for washing and dilution.…”

“…[12][13][14] Our recent in vitro studies showed that nitric oxide-mediated modification of TTR may serve an important function in amyloid formation, which indicates that oxidative stress facilitates amyloid formation. 15 Clinical phenotypes of patients with FAP, including the age at onset of disease and patterns of amyloid deposition, differ even in patients with the same TTR gene mutation. Some ATTR gene carriers never show any clinical manifestations throughout life.…”