Human T cell leukemia viruses (HTLVs) are complex human retroviruses of the Deltaretrovirus genus. Four types have been identified thus far, with HTLV-1 and HTLV-2 much more prevalent than HTLV-3 or HTLV-4. HTLV-1 and HTLV-2 possess strictly related genomic structures, but differ significantly in pathogenicity, as HTLV-1 is the causative agent of adult T cell leukemia and of HTLV-associated myelopathy/tropical spastic paraparesis, whereas HTLV-2 is not associated with neoplasia. HTLVs code for a protein named Tax that is responsible for enhancing viral expression and drives cell transformation. Much effort has been invested to dissect the impact of Tax on signal transduction pathways and to identify functional differences between the HTLV Tax proteins that may explain the distinct oncogenic potential of HTLV-1 and HTLV-2. This review summarizes our current knowledge of Tax-1 and Tax-2 with emphasis on their structure, role in activation of the NF-κB (nuclear factor kappa-B) pathway, and interactions with host factors.
Keywords: HTLV, Tax proteins, signal transduction, NF-κB
Citation: Romanelli MG, Diani E, Bergamo E, Casoli C, Ciminale V, Bex F and Bertazzoni U (2013) Highlights on distinctive structural and functional properties of HTLV Tax proteins. Front. Microbiol. 4:271. doi: 10.3389/fmicb.2013.00271
Received: 10 July 2013; Paper pending published: 30 July 2013;
Accepted: 20 August 2013; Published online: 09 September 2013.
Edited by:Akio Adachi, The University of Tokushima Graduate School, Japan
Reviewed by:Jun-ichi Fujisawa, Kansai Medical University, Japan
Copyright © 2013 Romanelli, Diani, Bergamo, Casoli, Ciminale, Bex and Bertazzoni. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
*Correspondence: Maria G. Romanelli, Department of Life and Reproduction Sciences, University of Verona, Strada le Grazie 8, 37134 Verona, Italy e-mail: email@example.com