| Research Abstract |
Familial amyloidotic polyneuropathy is an autosomal dominant disorder characterized by peripheral and sutonomic polyneuropathy. This disease was caused by the mutation in the transthyretin (ttr) gene, leading to systemic amyloidosis Amyloidogenic processes include dissociation of ttr tetramers into monomers, modification of monomers, aggregation of monomers, formation of amyloid fibrils, and attachment of serum amyloid P component (SAP) to amyloid fibrils. To elucidate the factors involved in these steps and to devise a new way of treatment, we tried to develop a casette exchnageable mouse using Cre-mutant lox system which was developed by ourselves. We made a vector for homologous recombination in ES cells, consisting of DT-A, 2.6 kb of homologous region of ttr, lox71, PGK-neo, loxP, poly A, lox2272, and 7.9kb homologous region of ttr. We produce chimeric mice that are now mating with female mice. To analyze the effects of intestinal flora, we transferred intestinal flora from SPF mic
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e as well as conventional mice housed in two different facilities 1 and 2 to transgenic mice. We found that amyloid was deposited in alimentary tract of transgenic mice transferred from conventional 2, but not from SPF and conventional 1, and that in conventional 2 condition symbiotes were decreased accompanied by an increase of weak pathogens while keeping. These suggest that intestinal flora can affect the amyloid deposition in alimentary tract. On the other hand, it is proposed that disulfide bond between cystein residues at position 10 in ttr molecule is prerequisite for aggregation of monomer. To test this possibility, we produce transgenic mice by introducing mutant ttr gene containing serine and methionine residues at position 10 and 30, respectively. Surprisingly, we could not observe amyloid deposition in these transgenic mice, although amyloid deposition was observed in transgenic mice carrying a mutant ttr gene carrying methionine at position 30. These results suggest that cystein residue at position 10 will be important for monomers to aggregate each other. We also tested whether CPHPC developed by Pepys et al. can remove SAP from serum and amyloid fibrils. We found that SAP was effectively removed from serum and amyloid deposits using transgenic mice carrying human SAP gene Less
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