HTLV-1 Yin and Yang: Rex and p30 Master Regulators of Viral mRNA Trafficking
Hicham H. Baydoun 1, Marcia Bellon 1, Christophe Nicot 1
1 NULL
*Correspondence: Christophe Nicot, Email not available
Abstract
Human retroviruses are associated with a variety of malignancies including Kaposi’s sarcoma andEpstein-Barr virus-associated lymphoma in HIV infection, T-cell leukemia/lymphoma and a neurologicdisorder in human T-cell lymphotropic virus type 1 (HTLV-1) infection. Both HIV and human T-cell lymphotropicvirus type 1 have evolved a complex genetic organization for optimal use of their limitedgenome and production of all necessary structural and regulatory proteins. Use of alternative splicingis essential for balanced expression of multiple viral regulators from one genomic polycistronic RNA.In addition, nuclear export of incompletely spliced RNA is required for production of structural andenzymatic proteins and virus particles. Decisions controlling these events are largely guarded by viralproteins. In human T-cell lymphotropic virus type 1, Rex and p30 are both nuclear/nucleolar RNA bindingregulatory proteins. Rex interacts with a Rex-responsive element to stimulate nuclear export ofincompletely spliced RNA and increase production of virus particles. In contrast, human T-cell lymphotropicvirus type 1 p30 is involved in the nuclear retention of the tax/rex mRNA leading to inhibitionof virus expression and establishment of viral latency. How these two proteins, with apparentlyopposite functions, orchestrate virus replication and ensure vigilant control of viral gene expressionis discussed.
