HTLV-2 tax immortalizes human CD4+ memory T lymphocytes by oncogenic activation and dysregulation of autophagy

Tong Ren, Wen Dong, Yoshinori Takahashi, Di Xiang, Yunsheng Yuan, Xin Liu, Thomas P. Loughran, Shao Cong Sun, Hong Gang Wang, Hua Cheng

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35 Scopus citations


Human T cell leukemia virus type 1 and type 2 (HTLV-1 and -2) are two closely related retroviruses with the former causing adult T cell leukemia. HTLV-2 infection is prevalent among intravenous drug users, and the viral genome encodes the viral transactivator Tax, which is highly homologous to the transforming protein Tax from HTLV-1. However, the link between HTLV-2 infection and leukemia has not been established. In the present study, we evaluated the activity of HTLV-2 Tax in promoting aberrant proliferation of human CD4 T lymphocytes. Tax2 efficiently immortalized CD4+ memory T lymphocytes with a CD3/TCRαβ/CD4/CD25/CD45RO/CD69 immunophenotype, promoted constitutive activation of PI3K/Akt, IκB kinase/NF-κB, mitogen-activated protein kinase, and STAT3, and it also increased the level of Mcl-1. Disruption of these oncogenic pathways led to growth retardation and apoptotic cell death of the Tax2-established T cell lines. We further found that Tax2 induced autophagy by interacting with the autophagy molecule complex containing Beclin1 and PI3K class III to form the LC3+ autophagosome. Tax2-mediated autophagy promoted survival and proliferation of the immortalized T cells. The present study demonstrated the oncogenic properties of Tax2 in human T cells and also implicated Tax2 in serving as a molecular tool to generate distinct T cell subtype lines.

Original languageEnglish (US)
Pages (from-to)34683-34693
Number of pages11
JournalJournal of Biological Chemistry
Issue number41
StatePublished - Oct 5 2012

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Molecular Biology
  • Cell Biology


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