title: Tax-1 and Tax-2 similarities and differences: focus on post-translational modifications and NF-κB activation.
abstract: Although human T cell leukemia virus type 1 and 2 (HTLV-1 and HTLV-2) share similar genetic organization, they have major differences in their pathogenesis and disease manifestation. HTLV-1 is capable of transforming T lymphocytes in infected patients resulting in adult T cell leukemia/lymphoma whereas HTLV-2 is not clearly associated with lymphoproliferative diseases. Numerous studies have provided accumulating evidence on the involvement of the viral transactivators Tax-1 versus Tax-2 in T cell transformation. Tax-1 is a potent transcriptional activator of both viral and cellular genes. Tax-1 post-translational modifications and specifically ubiquitylation and SUMOylation have been implicated in nuclear factor-kappaB (NF-κB) activation and may contribute to its transformation capacity. Although Tax-2 has similar protein structure compared to Tax-1, the two proteins display differences both in their protein-protein interaction and activation of signal transduction pathways. Recent studies on Tax-2 have suggested ubiquitylation and SUMOylation independent mechanisms of NF-κB activation. In this present review, structural and functional differences between Tax-1 and Tax-2 will be summarized. Specifically, we will address their subcellular localization, nuclear trafficking and their effect on cellular regulatory proteins. A special attention will be given to Tax-1/Tax-2 post-translational modification such as ubiquitylation, SUMOylation, phosphorylation, acetylation, NF-κB activation, and protein-protein interactions involved in oncogenecity both in vivo and in vitro.
authors: Department of Internal Medicine, Faculty of Medicine, American University of Beirut Beirut, Lebanon.
authors: Margret
authors: M
authors: Shirinian
authors: Youmna
authors: Y
authors: Kfoury
authors: Zeina
authors: Z
authors: Dassouki
authors: Hiba
authors: H
authors: El-Hajj
authors: Ali
authors: A
authors: Bazarbachi
keywords: HTLV-1; HTLV-2; NF-κB; Tax-1; Tax-2
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