Doppel-induced cytotoxicity in human neuronal SH-SY5Y cells is antagonized by the prion protein.
Doppel (Dpl) is a prion (PrP)-like protein due to the structural and biochemical similarities; however, the natural functions of Dpl and PrP remain unclear. In this study, a 531-bp human PRND gene sequence encoding Dpl protein was amplified from human peripheral blood leucocytes. Full-length and various truncated human Dpl and PrP proteins were expressed and purified from Escherichia coli. Supplement of the full-length Dpl onto human neuroblastoma cell SH-SY5Y induced remarkable cytotoxicity, and the region responsible for its cytotoxicity was mapped at the middle segment of Dpl [amino acids (aa) 81-122]. Interestingly, Dpl-induced cytotoxicity was antagonized by the presence of fulllength wild-type PrP. Analysis on fragments of PrP mutants showed that the N-terminal fragment (aa 23- 90) of PrP was responsible for the protective activity. A truncated PrP (PrPdelta32-121) with similar secondary structure as Dpl induced Dpl-like cytotoxicity on SHSY5Y cells. Furthermore, binding of copper ion could enhance the antagonizing effect of PrP on Dpl-induced cytotoxicity. Apoptosis assays revealed that cytotoxicity induced by Dpl occurred through an apoptotic mechanism. These results suggested that the function of Dpl is antagonistic to PrP rather than synergistic.
Li
Ping
P
State Key Laboratory for Infectious Disease Prevention and Control, National Institute for Viral Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China.
Dong
Chenfang
C
Lei
Yanjun
Y
Shan
Bing
B
Xiao
Xinli
X
Jiang
Huiying
H
Wang
Xin
X
Gao
Chen
C
Shi
Qi
Q
Xu
Kun
K
Tian
Chan
C
Han
Jun
J
Dong
Xiaoping
X
D017209:Apoptosis; D001483:Base Sequence; D015153:Blotting, Western; D045744:Cell Line, Tumor; D002470:Cell Survival; D017931:DNA Primers; D004926:Escherichia coli / Q000235:genetics; D058851:GPI-Linked Proteins; D006801:Humans; D009474:Neurons / Q000166:cytology* / Q000201:enzymology; D019001:Nitric Oxide Synthase / Q000378:metabolism; D016133:Polymerase Chain Reaction; D011328:Prions / Q000502:physiology*
D017931:DNA Primers; D058851:GPI-Linked Proteins; C501125:PRND protein, human; D011328:Prions; D019001:Nitric Oxide Synthase