Tuyển tập các báo cáo nghiên cứu về hóa học được đăng trên tạp chí sinh học đề tài : Molecular and cellular correlates of the CIITA-mediated inhibition of HTLV-2 Tax-2 transactivator function resulting in loss of viral replication | Orlandi et al. Journal of Translational Medicine 2011 9 106 http content 9 1 106 JOURNAL OF TRANSLATIONAL MEDICINE RESEARCH Open Access Molecular and cellular correlates of the CIITA-mediated inhibition of HTLV-2 Tax-2 transactivator function resulting in loss of viral replication Chiara Orlandi Greta Forlani Giovanna Tosi and Roberto S Accolla Abstract Background MHC class II transactivator CIITA inhibits the function of HTLV-2 Tax-2 viral transactivator and consequently the replication of the virus in infected cells. Moreover overexpression of the nuclear factor NF-YB that cooperates with CIITA for the expression of MHC class II genes results also in inhibition of Tax-2 transactivation. The purpose of this investigation was to assess the cellular and molecular basis of the CIITA-mediated inhibition on Tax-2 and the relative role of NF-YB in this phenomenon. Methods By co-immunoprecipitation of lysates from 293T cells cotransfected with CIITA or fragments of it and Tax-2 it was assessed whether the two factors interact in vivo. A similar approach was used to assess Tax-2-NF-YB interaction. In parallel deletion fragments of CIITA were tested for the inhibition of Tax-2-dependent HTLV-2 LTR-luciferase transactivation. Subcellular localization of CIITA and Tax-2 was investigated by immunofluorescence and confocal microscopy. Results CIITA and Tax-2 interact in vivo through at least two independent regions at the 1-252 N-term and at the 410-1130 C-term respectively. Interestingly only the 1-252 N-term region mediates Tax-2 functional inhibition. CIITA and Tax-2 are localized both in the cytoplasm and in the nucleus when separately expressed. Instead when coexpressed most of Tax-2 colocalize with CIITA in cytoplasm and around the nuclear membrane. The Tax-2 minor remaining nuclear portion also co-localizes with CIITA. Interestingly when CIITA nucleus-cytoplasm shuttling is blocked by leptomycin B treatment most of the Tax-2 molecules are
