Differential Degradation of Amyloid β Genetic Variants Associated with Hereditary Dementia or Stroke by Insulin-degrading Enzyme

Inherited amino acid substitutions at position 21, 22, or 23 of amyloid beta (Abeta) lead to presenile dementia or stroke. Insulin-degrading enzyme (IDE) can hydrolyze Abeta wild type, yet whether IDE is capable of degrading Abeta bearing pathogenic substitutions is not known. We studied the degradation of all of the published Abeta genetic variants by recombinant rat IDE (rIDE). Monomeric Abeta wild type, Flemish (A21G), Italian (E22K), and Iowa (D23N) variants were readily degraded by rIDE with a similar efficiency. However, proteolysis of Abeta Dutch (E22Q) and Arctic (E22G) was significantly lower as compared with Abeta wild type and the rest of the mutant peptides. In the case of Abeta Dutch, inefficient proteolysis was related to a high content of beta structure as assessed by circular dichroism. All of the Abeta variants were cleaved at Glu3-Phe4 and Phe4-Arg5 in addition to the previously described major sites within positions 13-15 and 18-21. SDS-stable Abeta dimers were highly resistant to proteolysis by rIDE regardless of the variant, suggesting that IDE recognizes a conformation that is available for interaction only in monomeric Abeta. These results raise the possibility that upregulation of IDE may promote the clearance of soluble Abeta in hereditary forms of Abeta diseases.Fil: Morelli, Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Físico-Química Biológicas "Prof. Alejandro C. Paladini". Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Química y Físico-Química Biológicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; ArgentinaFil: Llovera, Ramiro Esteban. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Físico-Química Biológicas "Prof. Alejandro C. Paladini". Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Química y Físico-Química Biológicas; ArgentinaFil: Gonzalez, Silvia Adriana. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Biológica. Laboratorio de Virología; ArgentinaFil: Affranchino, Jose Luis. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Biológica. Laboratorio de Virología; ArgentinaFil: Prelli, Frances. University of New York; Estados UnidosFil: Frangione, Blas. University of New York; Estados UnidosFil: Ghiso, Jorge. University of New York; Estados UnidosFil: Castaño, Eduardo Miguel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Físico-Química Biológicas "Prof. Alejandro C. Paladini". Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Química y Físico-Química Biológicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; Argentin

Copper chelation delays the onset of prion disease.

The prion protein (PrP) binds copper and under some conditions copper can facilitate its folding into a more protease resistant form. Hence, copper levels may influence the infectivity of the scrapie form of prion protein (PrP Sc ). To determine the feasibility of copper-targeted therapy for prion disease, we treated mice with a copper chelator, D-(؊)-penicillamine (D-PEN), starting immediately following intraperitoneal scrapie inoculation. D-PEN delayed the onset of prion disease in the mice by about 11 days (p ‫؍‬ 0.002), and reduced copper levels in brain by 29% (p < 0.01) and in blood by 22% (p ‫؍‬ 0.03) compared with control animals. Levels of other metals were not significantly altered in the blood or brain. Modest correlation was observed between incubation period and levels of copper in brain (p ‫؍‬ 0.08) or blood (p ‫؍‬ 0.04), indicating that copper levels are only one of many factors that influence the rate of progression of prion disease. In vitro, copper dose-dependently enhanced the proteinase K resistance of the prion protein, and this effect was counteracted in a dose-dependent manner by co-incubation with D-PEN. Overall, these findings indicate that copper levels can influence the conformational state of PrP, thereby enhancing its infectivity, and this effect can be attenuated by chelatorbased therapy

Immunomodulation Targeting Abnormal Protein Conformation Reduces Pathology in a Mouse Model of Alzheimer's Disease

Many neurodegenerative diseases are characterized by the conformational change of normal self-proteins into amyloidogenic, pathological conformers, which share structural properties such as high β-sheet content and resistance to degradation. The most common is Alzheimer's disease (AD) where the normal soluble amyloid β (sAβ) peptide is converted into highly toxic oligomeric Aβ and fibrillar Aβ that deposits as neuritic plaques and congophilic angiopathy. Currently, there is no highly effective treatment for AD, but immunotherapy is emerging as a potential disease modifying intervention. A major problem with most active and passive immunization approaches for AD is that both the normal sAβ and pathogenic forms are equally targeted with the potential of autoimmune inflammation. In order to avoid this pitfall, we have developed a novel immunomodulatory method that specifically targets the pathological conformations, by immunizing with polymerized British amyloidosis (pABri) related peptide which has no sequence homology to Aβ or other human proteins. We show that the pABri peptide through conformational mimicry induces a humoral immune response not only to the toxic Aβ in APP/PS1 AD transgenic mice but also to paired helical filaments as shown on AD human tissue samples. Treated APP/PS1 mice had a cognitive benefit compared to controls (p<0.0001), associated with a reduction in the amyloid burden (p = 0.0001) and Aβ40/42 levels, as well as reduced Aβ oligomer levels. This type of immunomodulation has the potential to be a universal β-sheet disrupter, which could be useful for the prevention or treatment of a wide range of neurodegenerative diseases

The Defect in µ Heavy Chain Disease Protein GLI

Summary Amino acid sequence studies of µHCD protein GLI reveal the absence of the amino terminal 130 residues. The molecule starts at Ala 131 and contains Cys 140, normally involved in the H-L disulfide bridges. Except for the deletion and presumably an extra H-H disulfide bridge involving Cys 140, the remainder of the µ-chain appears normal.</jats:p