Multiple Roles of Cellular Export Machinery in Htlv-1 Rex Functioning

摘要

Rex protein is a post-transcriptional regulator that is required for the expression of unspliced and incompletely spliced viral mRNAs that encode Gag and Env proteins. Rex binds directly Rex response element (RxRE) in human T cell leukemia virus type 1 (HTLV-1) RNAs and then undergoes multimerization on the RNA, which is necessary to export viral RNAs. Human CRMl, which is cellular machinery to export proteins from the nucleus to the cytoplasm, has been found to bind to Rex directly. Therefore, Rex executes its function by bridging viral RNAs and the cellular export machinery.In the first half of this review article we describe additional roles of CRMl in Rex functioning, such as involvement in Rex multimerization on RNA. In the latter half, we report that rat CRMl export little viral RNA because it has poor ability to induce the Rex multimerization. Our results suggest that the poor ability of rat CRMl as a cofactor of Rex may be responsible for the poor replication of HTLV-1 in rats. Such results provide a clue to means of improving presently incomplete rat models of HTLV-1 -related diseases.