Interaction between 14-3-3ß and PrP influences the dimerization of 14-3-3 and fibrillization of PrP106-126.

Proteins of the 14-3-3 family are universal participate in multiple cellular processes. However, their exact role in the pathogenesis of prion diseases remains unclear. In this study, we proposed that human PrP was able to form molecular complex with 14-3-3ß. The domains responsible for the interactions between PrP and 14-3-3ß were mapped at the segments of amino acid (aa) residues 106-126 within PrP and aa 1-38 within 14-3-3ß. Homology modeling revealed that the key aa residues for molecular interaction were D22 and D23 in 14-3-3ß as well as K110 in PrP. Mutations in these aa residues inhibited the interaction between the two proteins in vitro. Our results also showed that recombinant PrP encouraged 14-3-3ß dimer formation, whereas PrP106-126 peptide inhibited it. Recombinant 14-3-3ß disaggregated the mature PrP106-126 fibrils in vitro. Moreover, the PrP-14-3-3 protein complexes were observed in the brain tissues of normal and scrapie agent 263K infected hamsters. Colocalization of PrP and 14-3-3 was seen in the cytoplasm of human neuroblastoma cell line SH-SY5Y, as well as human cervical cancer cell line HeLa transiently expressing full-length human PrP. Our current data suggest the neuroprotection of PrPC and neuron damage caused by PrPSc may be associated with their functions of 14-3-3 dimerization regulation.

Infection of prions and treatment of PrP106-126 alter the endogenous status of protein 14-3-3 and trigger the mitochondrial apoptosis possibly via activating Bax pathway.

The 14-3-3 proteins are a family of highly homologous and ubiquitously expressed isoforms that are involved in a wide variety of physiological processes. 14-3-3 have showed actively molecular interaction with PrP and positive 14-3-3 is frequently observed in the cerebrospinal fluid (CSF) samples of the patients with sporadic Creutzfeldt-Jakob disease (CJD). However, the alterations of 14-3-3 in the brain tissues of patients with prion diseases remain little addressed. To address the possible change of brain 14-3-3 during prion infection, we firstly tested the levels of 14-3-3 in the brain tissues of scrapie agent 263 K infected hamsters. Obviously decreased 14-3-3 were observed in the samples of the infected animals, showing time-dependent reduction in the incubation period, while the amounts of S-nitrosylated 14-3-3 were increased in the brains collected at the late stage. A low level of 14-3-3 was also observed in the scrapie infectious cell line SMB-S15, accompanied with up-regulated Bax and down-regulated Bcl-2. Moreover, we found that treatment of PrP106-126 on the cultured cells decreased the cellular 14-3-3 and caused translocations of cellular Bax to the membrane fractions. Knockdown of cellular 14-3-3 sensitized the cultured cells to the challenge of PrP106-126. These data illustrate that significant down-regulation of brain 14-3-3 levels during prion infection may not only be a scenario of the terminal consequence of interacting with abnormal PrP(Sc) but may also participate in the pathogenesis of neuronal damage.

[The 2A protease of enterovirus 71 cleaves nup62 to inhibit nuclear transport].

To study the impact of the enterovirus 71(EV71) on the nuclear transport mechanism,The pGFP-NLS vector with nuclear location signal(NLS) was constructed, RD cells transfected by the pGFP-NLS vector were inoculated with the EV71 or cotransfected by EV71-2A vector. The results showed that GFP protein with NLS was expressed in the cytoplasm due to the inhibition of nuclear transport. In order to further study the mechanism of the EV71 to prevent nuclear transport,Nup62 was detected by Western blotting after RD cells were infected with EV71 or transfected by EV71-2A vector. The results showed that decreased expression of Nup62 could be detected after infection with EV71 and transfection by EV71-2A vector. This study demonstrates that the cleavage of Nup62 by EV71 2A protease may be the mechanism of nuclear transport inhibition.

[Human enterovirus 71 (EV71) resisted type I interferon induced antiviral effect].

OBJECTIVE: To investigate human enterovirus 71 (EV71) resistance to type I interferon induced antiviral effect. METHODS: After type I interferons (alpha, beta) were incubated with HeLa cells, recombinant type I herpes simple virus (HSV-1) with green fluorescent protein (GFP) was inoculated onto the HeLa cells. HSV-1 proliferation was observed by GFP expression and PCR. After EV71 was inoculated onto HeLa cells incubated with the same quantity of interferon, proliferation of EV71 were detected by RT-PCR of 2A gene. RESULTS: Recombinant HSV-1 GFP expression and viral DNA replication obviously decreased in HeLa cells incubated with type I interferon (alpha, beta). However, EV71 effectively proliferated in the interferon irritated HeLa cell by RT-PCR. CONCLUSION: HeLa cell irritated by type I interferon (alpha, beta) produced antiviral substance that inhibits HSV-1 proliferation. EV71 resisted the antiviral substance induced by type I interferon and could significantly replicate in the HeLa cells.