%A Ren,Tong %A Cheng,Hua %D 2013 %J Frontiers in Microbiology %C %F %G English %K HTLV-1/-2,tax,human T lymphocytes,Immortalization,transformation %Q %R 10.3389/fmicb.2013.00287 %W %L %M %P %7 %8 2013-September-23 %9 Hypothesis and Theory %+ Dr Hua Cheng,Penn State Hershey Cancer Institute,Hershey,Pennsylvania,United States,hcheng@ihv.umaryland.edu %# %! The activities of the retroviral Tax proteins in T cell transformation %* %< %T Differential transforming activity of the retroviral Tax oncoproteins in human T lymphocytes %U https://www.frontiersin.org/articles/10.3389/fmicb.2013.00287 %V 4 %0 JOURNAL ARTICLE %@ 1664-302X %X Human T cell leukemia virus type 1 and type 2 (HTLV-1 and -2) are two closely related retroviruses. HTLV-1 causes adult T cell leukemia and lymphoma, whereas HTLV-2 infection is not etiologically linked to human disease. The viral genomes of HTLV-1 and -2 encode highly homologous transforming proteins, Tax-1 and Tax-2, respectively. Tax-1 is thought to play a central role in transforming CD4+ T lymphocytes. Expression of Tax-1 is crucial for promoting survival and proliferation of virally infected human T lymphocytes and is necessary for initiating HTLV-1-mediated oncogenesis. In transgenic mice and humanized mouse model, Tax-1 has proven to be leukemogenic. Although Tax-1 is able to efficiently transform rodent fibroblasts and to induce lymphoma in mouse model, it rarely transforms primary human CD4+ T lymphocytes. In contrast, Tax-2 efficiently immortalizes human CD4+ T cells though it exhibits a lower transforming activity in rodent cells as compared to Tax-1. We here discuss our recent observation and views on the differential transforming activity of Tax-1 and Tax-2 in human T cells.