The Mechanism Of Tat Degradation Promoted By Triptolide

Human immunodeficiency virus(HIV-1)is the primary retroviral agent responsible for AIDS.One of its identified gene products,Tat protein,plays a pivotal role in HIV-1 transcription,which functions as "on and off" switch in HIV-1 latency and activation.Focusing on regulation of Tat is important for elucidating principle of HIV-1 gene transcriptional elongation and developing new drug target for AIDS therapy.Triptolide(TPL)is a famous Chinese herbal medicine component,which can be served as a drug in treating self-immune disease,cancer and other diseases.Its effect on HIV-1 was reported recently,thus in this assay,we want to reveal the mechanism behind Tat degradation promoted by TPL,which serve as a drug model to explore a potential drug target and a new thought in HIV-1 therapy.Based on our cell model for studying HIV-1 transcription,compared with other active ingredients extracted from tripterygium,TPL has a better effect on inhibition in HIV-1 transcription in a time and dose dependent manner,suggesting that the mechanism behind the inhibition is that TPL could induce Tat degradation specifically,which is neither through blocking CycTl protection for Tat,nor affecting transcription or translation,but in an ubiquitin proteasome pathway.Results show that 1234 proteins,including 12 E3 ubiquitin ligase,by performing affinity purification,mass spectra,SILAC(stable isotopic labeling by amino acids in cell culture).Most noteworthy is that CUL4B is involved in Tat degradation under natural condition while not TPL treatment,and TPL doesn't induce Tat degradation in mono-site ubiquitination.