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Abstract

We demonstrate that the levels of native as well as transfected prion protein (PrP) are lowered in various cell lines exposedto phosphorothioate oligodeoxynucleotides (PS-DNA) and can be rapidly reverted to their normal amounts by removal of PS-DNA.This transient modulation was independent of the glycosylation state of PrP, and in addition, all three PrP glycoforms weresusceptible to PS-DNA treatment. Deletion of the N-terminal domain (amino acids 23–99), but not of the other domains of PrP,abrogated its PS-DNA-mediated down-regulation. PrP versions localized in the mitochondria, cytoplasm, or nucleus were notmodulated by PS-DNA, indicating that PrP surface exposure is required for executing this effect. Proteins that in their nativeforms were not responsive to PS-DNA, such as thymocyte antigen 1 (Thy1), Doppel protein (Dpl), green fluorescent protein (GFP),and cyan fluorescent protein (CFP), became susceptible to PS-DNA-mediated down-regulation following introduction of the Nterminus of PrP into their sequence. These observations demonstrate the essential role of the N-terminal domain for promotingoligonucleotide-mediated reduction of the PrP level and suggest that transient treatment of cultured cells with PS-DNA mayprovide a general method for targeted modulation of the levels of desired surface proteins in a conditional and reversiblemanner.