NR AWNB
AU Sakasegawa,Y.; Doh-ura,K.
TI Aggregation and degradation of cellular prion protein by novobiocin
QU International Conference - Prion 2006: Strategies, advances and trends towards protection of society - 3.10.-6.10.2006, Torino, Italy, Lingotto Conference Centre - Poster sessions CE-45
PT Konferenz-Poster
AB A coumarin antibiotic, novobiocin, is known either as a drug depleting the cellular prion protein (PrPc) from cells or as an inhibitor of the C-terminal chaperone domain of heat shock protein 90 kDa (Hsp90). To elucidate the molecular mechanism of novobiocin-induced depletion of PrPc from cells, we investigated the interaction between PrPc and Hsp90 in vitro and in cultured cells. Incubation of soluble monomeric recombinant prion protein (rPrP) with more than 10 M novobiocin induced its misfolding and aggregation in vitro in a manner irrespective of the involvement of Hsp90. Novobiocin-induced rPrP aggregates were resistant to limited proteolytic digestion and had higher molecular weight in sucrose density gradient centrifugation analysis. When recombinant Hsp90 was added to the mixture of rPrP and novobiocin, it bound to novobiocin-induced rPrP aggregates but not to monomeric rPrP, indicating that in the presence of novobiocin, Hsp90 bound to the PrP aggregates can not depolymerize or unfold/refold the PrP aggregates. Either cell fractionation analysis or indirect immunofluorescent microscopical analysis demonstrated that some portions of PrPc on the membrane was coexist or colocalized with some of membrane-associated Hsp90 in Neuro2a neuroblastoma cells. The findings suggests the followings; novobiocin directly causes misfolding and aggregation of PrPc; novobiocin-induced PrPc aggregates are recognized by cell membrane associated Hsp90. Finally, it might be hypothesized that the PrPc-Hsp90 complex formation triggers the degradation of PrPc via an unidentified Hsp90-related protein degradation pathway, but it remains to be explored.
AD Department of Prion Research, Tohoku University Graduate School of Medicine, Sendai, Japan. E-mail: ysakase@mail.tains.tohoku.ac.jp
SP englisch
PO Italien