Prion-Protein-Specific Aptamer Reduces PrPSc Formation

Abstract

The critical initial event in the pathophysiology of transmissible spongiform encephalopathies (TSEs) appears to be the conversion of the cellular prion protein (PrP C ) into the abnormal isoform PrP Sc . This isoform forms high-molecular-weight protease K (PK) resistant aggregates that accumulate in the central nervous system of affected individuals. We have selected nuclease-resistant 2'-amino-2'-deoxypyrimidine-modified RNA aptamers which recognize a peptide comprising amino acid residues 90 ± 129 of the human prion protein with high specificity. This domain of prion proteins is thought to be functionally important for the conversion of PrP C into its pathogenic isoform PrP Sc and is highly homologous among prion proteins of various species including mouse, hamster, and man. Consequently, aptamer DP7 binds to the full-length human, mouse, and hamster prion protein. At low concentrations in the growth medium of persistently prion-infected neuroblastoma cells, aptamer DP7 significantly reduced the relative proportion of de novo synthesized PK-resistant PrP Sc within only 16 h. These findings may open the door towards a rational development of a new class of drugs for the therapy or prophylaxis of prion diseases.

Detection of prion epitopes on PrPc and PrPsc of transmissible spongiform encephalopathies using specific monoclonal antibodies to PrP

“…Those anti-PrP not recognizing PrP sc plaques were raised from PrP knockout mice immunized with the peptide-carrier conjugated with EDC linker; this conjugate has the potential to form different conformational structures. The results suggest that the region of PrP93-112 does undergo conformational change in PrP sc conversion and that is in agreement with the findings of Peretz et al 15 However, the different reaction profiles of our anti-PrP suggests that residues PrP93-102 are exposed in PrP c but buried upon conversion to the PrP sc form, whereas PrP103-107 residues are partially buried in PrP sc but only the PrP107-115 epitope remains exposed on both 30 showed that a specific synthetic nucleic acid binder RNA aptamer that recognizes PrP90-129 residues also has an inhibitory effect on PrP sc formation, whereas several other studies, including a recent study by Féraudet et al, 34 have shown that binding of some anti-PrP antibodies to cell-surface PrP c could inhibit PrP sc formation and that one such anti-PrP recognizes the epitope PrP97-102. Taken together, these results indicate that the epitopes in this region may also be involved in binding of PrP c to PrP sc .…”

Anti-bovine Prion protein RNA aptamer containing tandem GGA repeat interacts both with recombinant bovine prion protein and its β isoform with high affinity

“…The capacity of these adenine sequences to bind to bPrPs was investigated. The have described G-quadruplex forming RNA aptamers for PrP, 10,11 but sequences are different from described here.…”

“…Aptamers are artificial nucleotides derived from systematic evolution of ligands by exponential enrichment (SELEX), 6,7 which bind a wide range of targets with a high affinity and specificity, as is seen with antibodies. 8,9 Using this method, many aptamers specific to PrP [10][11][12][13][14][15][16][17][18][19][20] and PrP Sc , 12,13 have been isolated.…”

A Novel, Modification-Dependent ATP-Binding Aptamer Selected from an RNA Library Incorporating a Cationic Functionality

“…In vitro selection is a combinatorial technique that generates receptors, ligands, and catalysts from nucleic acid libraries containing as many as 10 14 -10 16 different molecules and is a powerful method to explore the sequence space of biopolymers in search of functional domains. Some effort has been devoted to developing in vitro selection processes that use modified monomer triphosphates as substrates for polymerases (27)(28)(29)(30)(31)(32)(33)(34)(35)(36), and several in vitro selection experiments have been undertaken to select for catalysts or aptamers whose functions depend on the presence of modified nucleotides (37)(38)(39)(40)(41)(42)(43)(44)(45)(46)(47)(48), with notable success (39,40,(43)(44)(45)(46)(47). On the other hand, modified building blocks have not proven to always be critical in obtaining superior receptors or catalysts (40,42,48,49).…”