Doppel-induced cytotoxicity in human neuronal SH-SY5Y cells is antagonized by the prion protein

• Published in: Acta biochimica et biophysica Sinica 2009-01, Vol.41 (1), p.42-53
• Main Authors: Li, Ping, Dong, Chenfang, Lei, Yanjun, Shan, Bing, Xiao, Xinli, Jiang, Huiying, Wang, Xin, Gao, Chen, Shi, Qi, Xu, Kun, Tian, Chan, Han, Jun, Dong, Xiaoping
• Format: Article
• Language: English
• Subjects: Apoptosis; Base Sequence; Blotting, Western; Cell Line, Tumor; Cell Survival; DNA Primers; Escherichia coli; Escherichia coli - genetics; GPI-Linked Proteins; Humans; Neurons - cytology; Neurons - enzymology; Nitric Oxide Synthase - metabolism; Polymerase Chain Reaction; Prions - physiology
• ISSN: 1672-9145; 1745-7270
• DOI: 10.1093/abbs/gmn005

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 full-length 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 (PrPΔ32-121) with similar secondary structure as Dpl induced Dpl-like cytotoxicity on SH-SY5Y 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.