There are two sections included in this thesis： One studies the role of MAPK signal transduction in the anti-HIV-1 activity of trichosanthin (TCS). TCS is a type I ribosome-inactivating protein with a molecular weight of 27 kilodaltons. It is purified from the root of a traditional mid-term abortive and anti-choriocarcinoma Chinese herb medicine, with a Chinese name Tian-Hua-Fen. This protein possesses broad-spectrum of biolological and pharmaceutical properties, such as immunosupression, mid-term abortion and antiviral activities, in addition to killing leukemia, lymphoma and other tumor potential. At the end of 1980’s, more researchers were attracted to study TCS after McGrath et al found that the plant protein could inhibit HIV-1 replication. But its anti-HIV-1 mechanism is still uncertain. A specific JNK pathway inhibitor, CEP-11004, was used to pretreat host cells and the influence of this inhibitor on the anti-HIV-1 activity of TCS was assayed. The results showed that CEP-11004 could counteract the anti-virus activity of TCS in C8166 cells. CEP-11004 alone had no effect in HIV-1 replication and TCS alone significantly inhibited this process. When CEP-11004 was used together with TCS, the antiviral action of TCS was much reduced. Two methods were used to assess viral replication. (1) By measuring the HIV-1 reverse transcriptase, TCS on the average reduced viral replication to 52 ± 4%. With CEP-11004 pretreatment, TCS appeared to lose the HIV-1 inhibitory activity with viral replication stood at 101 ± 7%. (2) By measuring HIV-1 p24, TCS reduced viral replication to 68 ± 4%. With CEP-11004 pretreatment, TCS again seemed to lose its anti-HIV-1 activity with HIV-1 replication rose back to 101 ± 4%. Both index indicated that CEP-11004 counteracted the antiviral action of TCS. The result demonstrated that some of the components of cell signal tranduction pathway that could be inhibited by CEP-11004 were related to the anti-HIV-1 activity of TCS. And Western Blot assay showed that TCS potentiated JNK activation in a time- and dose-dependent manner, while 0.4 μM CEP-11004 could effectively suppress JNK phosphorylation. The results suggested that MAPK signal transduction was involved in the anti-HIV-1 activity of TCS. The other part of this thesis is on the study of syncytin, the envelope gene of HERV-W. It is specifically expressed in human placenta and might be involved in syncytiotrophoblast morphogenesis, less expressed in testes. Real-time RT-PCR method was recruited in this study and the results showed that this gene was also expressed in leukemia cell lines. Further research demonstrated that syncytin mRNA was expressed in the peripheral blood cells of leukemia patients (11 out of 15 samples), but was not expressed in the blood cells of 10 healthy donors using as control samples. Syncytin expression level in C8166 cell line was set as 1.0. Then relative syncytin expression levels of all tested cell lines were between 0.5 and 2.0, while that in patients’ samples varied from 0.8 to 21.7 folds. Our results suggested that aberrant expression of this gene might be involved in leukemogenesis.
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