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P2‐352: Effects of anti‐Aβ oligomer treatment on synaptic density in young Tg2576 mice: A preclinical model for measuring Alzheimer's disease modification
Author(s) -
Perez-Cruz Claudia,
Janson Bodo,
Nolte Marc,
Rustay Nathan,
Hillen Heinz,
Kirchhoff Frank,
Ebert Ulrich
Publication year - 2008
Publication title -
alzheimer's and dementia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.713
H-Index - 118
eISSN - 1552-5279
pISSN - 1552-5260
DOI - 10.1016/j.jalz.2008.05.1430
Subject(s) - dendritic spine , hippocampus , genetically modified mouse , soma , chemistry , basal (medicine) , alzheimer's disease , amyloid (mycology) , hippocampal formation , medicine , endocrinology , biology , pathology , neuroscience , transgene , biochemistry , disease , insulin , gene
(scFvs; these constructs mimic the VL-VH paired structure of physiological Igs) along with a few unusual IgVs generated by cloning errors. Methods: A hydrolysis by the IgVs was monitored by radioassay and mass spectrometry. Mutations (4-6/IgV molecule) were introduced by error prone replication. Specific nucleophilic IgVs displayed on phages were selected by covalent binding to an electrophilic A analog. Results: Screening and phage selection procedures identified rare catalystic IgVs with exceptional hydrolytic activity directed at the His14-Gln15 bond of A . Irrelevant proteins were not hydrolyzed. The activities were sufficient to ensure hydrolysis of 10 A molecules/catalyst molecule over 10 days, corresponding to the approximate half-life of full-length IgG in circulation. The IgVs had unusual structures containing heterodimeric VL segments (IgVL2) or an unpaired, intact VL segment linked to a truncated VH peptide (IgVL). Repair of the aberrant VH segment in an IgVL clone yielded scFv constructs with substantially reduced A hydrolyzing activity. Random mutagenesis of an IgVL2 construct followed by covalent phage selection permitted isolation of clones with 40-fold improved A hydrolyzing activity. An electrophilic hapten reacted irreversibly with the IgVs, suggesting that the A hydrolysis reaction occurs via a nucleophilic catalytic mechanism. Molecular modeling suggested the presence of serine proteaselike catalytic sites in the VL domains. Conclusions: Unlike physiological Igs, the IgVL scaffold supports exceptional A hydrolytic activity and represents a new molecular format suitable for development of catalytic AD immunotherapy.