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There is accumulating evidence of the involvement of biological metal imbalance in the progression of amyloid diseases such as Alzheimer's, Parkinson's and prion diseases. However, the mineral status in patients affected with familial amyloidotic polyneuropathy (FAP) has not been investigated. It is the aim of this study to determine the metal concentrations in the serum and in the transthyretin (TTR) amyloid fibrils of FAP amyloidogenic TTR (ATTR) V30M patients. Multi-elemental analysis of 17 metals by high-resolution inductively coupled plasma mass spectrometry (ICP-MS) revealed a significant decrease of the metals Fe, Cu, Zn, Cs and Ba in the serum of FAP patients (mean age 38.5 ± 8.3 years; duration of disease 4 ± 2.6 years) in comparison with that of healthy individuals (mean age 36.2 ± 9.2 years). On the other hand, these metals, except Cs, were found at high levels in the amyloid fibrils of FAP patients (mean age 55.8 ± 9.2; duration of disease 6.5 ± 1.3 years) compared with other metals. These findings firstly suggest that the mineral status could be a candidate factor, which participates in the wide spectrum of clinical pictures of FAP patients. [ABSTRACT FROM AUTHOR]

Abstract: Transthyretin (TTR) amyloid fibril formation, which is triggered by the dissociation of tetrameric TTR, appears to be the causative factor in familial amyloidotic polyneuropathy and senile systemic amyloidosis. Binding of thyroxine (T4), a native ligand of TTR, stabilizes the tetramer, but the bioavailability of T4 for TTR binding is limited due to the preferential binding of T4 to globulin, the major T4 carrier in plasma. Here, we show that Cr3+ increased the T4-binding capacity of wild-type (WT) and amyloidogenic V30M-TTR. Moreover, we demonstrate that Cr3+ and T4 cooperatively suppressed in vitro fibril formation due to the stabilization of WT-TTR and V30M-TTR. [Copyright &y& Elsevier]

Transthyretin-related amyloidosis is a slowly progressive disorder caused by deposition of insoluble amyloid plaques formed by fibrillization of mutant or defective transthyretin (TTR) monomers that leads to neurodegeneration and organ failure. Thus, any compound exhibiting TTR amyloid formation inhibitory activity or TTR amyloid fibril disrupting activity might be a potential candidate for the development of therapies for these disorders. Our aim in this study was the evaluation of the TTR amyloid fibril disrupting potential of extracts of leaves and immature fruits of two Juglans plants, i.e., Juglans mandshurica var. sachalinensis and Juglans mandshurica var. cordiformis. The TTR amyloid fibril disrupting activity was measured by Thioflavin-T (ThT) assay and PROTEOSTAT® Protein aggregation assay methods. A fifty percent acetone extract of the fruits of Juglans mandshurica var. cordiformis showed strong amyloid fibril disrupting activity, and was further fractionated using different solvents. Ethyl acetate and n-butanol fractions showed significant activity in both assays. Syringic acid was isolated and identified as main compound in both of these fractions; however, it did not show any activity. Furthermore, some of the previously reported compounds from Juglans plants including naphthoquinone derivatives and phenolic compounds were evaluated to identify the potential bioactive compounds. Among them, juglone, a naphthoquinone derivative showed promising activity. However, juglone also showed strong cytotoxicity in HEK293 cells. Thus, future studies should focus on the isolation and identification of naphthoquinone derivatives or other compounds from Juglans plan ts with potent bioactivity and low cytotoxicity. [ABSTRACT FROM AUTHOR]

Amyloid fibril formation is associated with protein misfolding disorders, including neurodegen- erative diseases such as Alzheimer's, Parkinson's, and Huntington's diseases. Familial amyloid polyneuro- pathy (FAP) is a hereditary disease caused by a point mutation of the human plasma protein, transthyretin (TTR), which binds and transports thyroxine (T4). TTR variants contribute to the pathogenesis of amyloi- dosis by forming amyloid fibrils in the extracellular environment. A recent report showed that epigalloca- techin 3-gallate (EGCG), the major polyphenol component of green tea, binds to TFR and suppresses TTR amyloid fibril formation. However, structural analysis of EGCG binding to TTR has not yet been conducted. Here we first investigated the crystal structure of the EGCG-V3OM `FrR complex and found novel binding sites distinct from the thyroxine binding site, suggesting that EGCG has a mode of action different from those of previous chemical compounds that were shown to bind and stabilize the TTR tetramer structure. Furthermore, EGCG induced the oligomerization and monomer suppression in the cellular system of clinically reported TTR variants. Taken together, these findings suggest the possibility that EGCG may be a candidate compound for FAP therapy. [ABSTRACT FROM AUTHOR]

Amyloid fibril formation of mutant transthyretin (TTR) that causes familial amyloid polyneuropathy occurs in the extracellular space. Thus, secretion of TTR variants contributes to the pathogenesis of amyloidosis. However, the molecular mechanisms underlying the endoplasmic reticulum (ER) exit or retention and subsequent degradation of TTR variants remain unclear. Here, we demonstrated that the nonsecreted TTR variants, such as D18G TTR and amyloidogenic TTRs with introduced monomeric mutation (M-TTRs), stably interact with the ER chaperone BiP in mammalian cells. These proteins were co-secreted with the secreted form of BiP in which the KDEL signal was removed, indicating that BiP partially contributes to the ER retention of nonsecreted TTR variants. More interestingly, the degradation efficiency of nonsecreted TTRs was increased when BiP was down-regulated by small interfering RNA. Thus, BiP protects the TTR variants from immediate degradation. Additionally, we showed that the stability of nonsecreted TTR variants is not disturbed in the coat complex Il-deficient conditions, which are enough to inhibit the ER export of secreted TTR variants, including wild-type TTR. Therefore, the post-ER retrieval mechanism might not contribute to the ER-associated degradation of nonsecreted TTR variants. These findings suggest that the affinity to the ER-resident protein BiP regulates the fate of TTR variants in the ER. [ABSTRACT FROM AUTHOR]

Background: Transgenic mice carrying a human mutant transthyretin (TTR) gene are too small for in vivo experiments. It is necessary to have rat TTR protein and its antibody to overcome this problem. Methods: Posttranslational modification of purified TTR was analyzed by means of matrix-assisted laser desorption ionization/time-of-flight mass spectrometry (MALDI/TOF-MS). Production of amyloid fibrils in vitro was confirmed by thioflavin T test and electron microscopy. Amyloidogenicity of rat TTR from rats with or without challenging paraquat was compared in vitro by thioflavin T test. Results: MALDI/TOF-MS for rat TTR revealed three major modified forms—sulfate-conjugated, Cys-conjugated and glutathione-conjugated—in addition to the unconjugated (free) form of TTR. Although rat TTR in buffer of pH 7.0 could not make amyloid fibrils, rat TTR at pH 2.0–3.5 significantly formed amyloid fibrils, as confirmed by the thioflavin T test and electron microscopy. TTR purified from rats administered 4 mg/kg of paraquat formed much more amyloid fibrils than that from normal rats at pH 2.0–3.5 and significant amyloid fibrils were confirmed even at pH 7.0. Conclusions: Rat TTR may be a valuable experimental tool for examination of the amyloidogenicity of senile systemic amyloidosis (SSA) as well as familial amyloidotic polyneuropathy (FAP) both in vitro and in vivo. [Copyright &y& Elsevier]