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  • Open Access

HTLV-1-mediated dysregulation of the Wnt pathways: roles of Tax and HBZ

  • 1,
  • 1Email author,
  • 1,
  • 2 and
  • 1
Retrovirology201411 (Suppl 1) :P91

https://doi.org/10.1186/1742-4690-11-S1-P91

  • Published:

Keywords

  • Wnt5a Expression
  • bZIP Factor
  • Cell Leukemia Virus Type
  • Transactivating Ability
  • Induce Wnt5a Expression

Human T cell leukemia virus type 1 (HTLV-1) is the causative agent of adult T-cell leukemia (ATL). Dysregulations of cellular signaling pathways have been considered to be important strategies for HTLV-1 induced leukemogenesis. In this study, we found that a Wnt pathway-related protein, Dishevelled (Dvl)-associating protein with a high frequency of leucine residues (DAPLE), could be associated with Tax to activate the canonical Wnt signaling. However, in the downstream of the pathway, T-cell factor 1 (TCF1) and lymphoid enhancer-binding factor 1 (LEF1), which are two transcription factors mainly expressed in T-cells, could interact with Tax and suppress its transactivating ability. We further found virus production was greatly inhibited by TCF1/LEF1. Due to the high expression of TCF1/LEF1 in the thymus and their significant downregulation upon T-cell activation, we suspect TCF1/LEF1 may contribute to the HTLV-1 tropism on activated mature T-cells. On the other hand, HTLV-1 bZIP factor (HBZ) markedly suppressed canonical Wnt activation through targeting both TCF1 and LEF1. As a result, the canonical Wnt pathway was not activated in HTLV-1-infected cells, whereas the representative of noncanonical Wnt ligands, Wnt5a, which antagonizes canonical Wnt signaling, was overexpressed in HTLV-1 infected cells. Further experiments revealed HBZ could induce Wnt5a expression through activation of the TGF-β pathway. Importantly, knocking down of Wnt5a in HTLV-1-infected cells repressed cellular proliferation and migration. By suppressing the canonical and enhancing the noncanonical Wnt pathway, HBZ is likely able to generate a favorable environment for HTLV-1 infection and persistence.

Authors’ Affiliations

(1)
Laboratory of Virus Control, Institute for Virus Research, Kyoto University, Kyoto, Japan
(2)
Laboratory of Gene Analysis, Institute for Virus Research, Kyoto University, Kyoto, Japan

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