Supattapone S, Wille H, Uyechi L, Safar J, Tremblay P, Szoka F C, Cohen F E, Prusiner S B, Scott M R
Institute for Neurodegenerative Diseases, University of California at San Francisco, San Francisco, California 94143, USA.
J Virol. 2001 Apr;75(7):3453-61. doi: 10.1128/JVI.75.7.3453-3461.2001.
Branched polyamines, including polyamidoamine and polypropyleneimine (PPI) dendrimers, are able to purge PrP(Sc), the disease-causing isoform of the prion protein, from scrapie-infected neuroblastoma (ScN2a) cells in culture (S. Supattapone, H.-O. B. Nguyen, F. E. Cohen, S. B. Prusiner, and M. R. Scott, Proc. Natl. Acad. Sci. USA 96:14529-14534, 1999). We now demonstrate that exposure of ScN2a cells to 3 microg of PPI generation 4.0/ml for 4 weeks not only reduced PrP(Sc) to a level undetectable by Western blot but also eradicated prion infectivity as determined by a bioassay in mice. Exposure of purified RML prions to branched polyamines in vitro disaggregated the prion rods, reduced the beta-sheet content of PrP 27-30, and rendered PrP 27-30 susceptible to proteolysis. The susceptibility of PrP(Sc) to proteolytic digestion induced by branched polyamines in vitro was strain dependent. Notably, PrP(Sc) from bovine spongiform encephalopathy-infected brain was susceptible to PPI-mediated denaturation in vitro, whereas PrP(Sc) from natural sheep scrapie-infected brain was resistant. Fluorescein-labeled PPI accumulated specifically in lysosomes, suggesting that branched polyamines act within this acidic compartment to mediate PrP(Sc) clearance. Branched polyamines are the first class of compounds shown to cure prion infection in living cells and may prove useful as therapeutic, disinfecting, and strain-typing reagents for prion diseases.
包括聚酰胺胺和聚丙烯亚胺（PPI）树枝状大分子在内的支链多胺，能够在培养物中从感染羊瘙痒病的神经母细胞瘤（ScN2a）细胞中清除朊病毒蛋白的致病异构体PrP(Sc)（S. Supattapone、H.-O. B. Nguyen、F. E. Cohen、S. B. Prusiner和M. R. Scott，《美国国家科学院院刊》96:14529 - 14534，1999年）。我们现在证明，将ScN2a细胞暴露于浓度为3微克/毫升的第4代PPI中4周，不仅能将PrP(Sc)降低至Western印迹检测不到的水平，还能如通过小鼠生物测定所确定的那样根除朊病毒感染性。体外将纯化的RML朊病毒暴露于支链多胺会使朊病毒杆解体，降低PrP 27 - 30的β-折叠含量，并使PrP 27 - 30易于被蛋白酶水解。支链多胺在体外诱导的PrP(Sc)对蛋白酶消化的敏感性具有毒株依赖性。值得注意的是，来自感染牛海绵状脑病的大脑的PrP(Sc)在体外易受PPI介导的变性影响，而来自自然感染羊瘙痒病的大脑的PrP(Sc)则具有抗性。荧光素标记的PPI特异性地积聚在溶酶体中，这表明支链多胺在这个酸性区室中发挥作用以介导PrP(Sc)的清除。支链多胺是第一类被证明能治愈活细胞中朊病毒感染的化合物，可能被证明可作为朊病毒疾病的治疗、消毒和毒株分型试剂。
