1. M-Sec promotes the accumulation of intracellular HTLV-1 Gag puncta and the incorporation of Env into viral particles.
- Author
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Hiyoshi, Masateru, Eltalkhawy, Youssef M., Abdelnaser, Randa A., Ono, Akira, Monde, Kazuaki, Maeda, Yosuke, Mahmoud, Reem M., Takahashi, Naofumi, Hatayama, Yasuyoshi, Ryo, Akihide, Nozuma, Satoshi, Takashima, Hiroshi, Kubota, Ryuji, and Suzu, Shinya
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HTLV-I , *VIRAL envelope proteins , *GAG proteins , *CYTOSKELETAL proteins , *VIRAL proteins - Abstract
We have demonstrated that the cellular protein M-Sec promotes the transmission of human T-cell leukemia virus type 1 (HTLV-1) in vitro and in vivo. Here, we show how HTLV-1 utilizes M-Sec for its efficient transmission. HTLV-1-infected CD4+ T cells expressed M-Sec at a higher level than uninfected CD4+ T cells. The ex vivo culture of the infected cells upregulated the expression of M-Sec, the level of which was sustained for a long time. The viral structural protein Gag is distributed in a punctate pattern in cells. M-Sec promoted the accumulation of large intracellular Gag puncta. This accumulation was dependent on phosphatidylinositol 4,5-bisphosphate (PIP2), since it was lost upon the removal of PIP2 binding motifs in M-Sec or the depletion of cellular PIP2. The viral envelope protein Env co-localized with the large Gag puncta induced by M-Sec. Furthermore, viral particles produced by M-Sec-expressing cells contained a higher amount of Env. Given that M-Sec alters the cellular distribution of PIP2, these results suggest that M-Sec promotes the formation of infectious viral particles through PIP2. Since the expression of M-Sec is mediated by HTLV-1 Tax protein, M-Sec appears to function in a positive feedback loop that ensures efficient HTLV-1 transmission. Author summary: Human T-cell leukemia virus type 1 (HTLV-1) causes an aggressive blood cancer known as ATL and a neurodegenerative condition known as HAM/TSP. HTLV-1 infects CD4+ T lymphocytes, and induces or upregulates the expression of a wide array of cellular proteins, including M-Sec. Our previous in vitro and in vivo studies have demonstrated that M-Sec mediates an efficient cell-to-cell transmission of HTLV-1. In this study, we discovered that M-Sec can also facilitate virus spread by promoting the formation of infectious viral particles. Mechanistically, our data suggest that through redistribution of phosphatidylinositol 4,5-bisphosphate, M-Sec promotes accumulation of a viral structural protein Gag and an envelope protein Env to large intracellular compartments, and facilitates the incorporation of Env into progeny viral particles. Thus, the current study reveals that M-Sec and its downstream effectors are key host components that govern both the virion infectivity and cell-to-cell transmission and thereby potentially serve as targets of anti-HTLV-1 strategies. [ABSTRACT FROM AUTHOR]
- Published
- 2025
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