Viral oncogenesis and genomic instability: the centr(osom)al connection.

Currently, more than 10% of human cancers are associated with viral infection. Studies on oncoviruses led to the development of clinical intervention strategies and elucidated fundamental cellular events altered upon cell transformation. Cancer cells exhibit several hallmarks including genomic instability, defined as a high frequency of mutations including gain or loss of chromosomes. The centrosome is an organelle that governs mitotic chromosome segregation and that functions as a signaling platform downstream of the DNA damage response. Here, we review the current literature to highlight how oncoviruses induce genomic instability via the deregulation of the centrosome. Viral interference with the centrosome duplication cycle, leading to centrosome amplification, is illustrated, with a special emphasis on mechanisms shared by several viral families. In addition, we discuss how oncoviruses could alter the signaling functions of the centrosome, and we comment on the bibliographic gaps that could be addressed by future research.

[Viral oncogenesis and genomic instability: the centr(osom)al connection]. / Oncogenèse virale et instabilité génomique : la connexion centr(osom)ale.

Currently, more than 10% of human cancers are associated with viral infection. Studies on oncoviruses led to the development of clinical intervention strategies and elucidated fundamental cellular events altered upon cell transformation. Cancer cells exhibit several hallmarks including genomic instability, defined as a high frequency of mutations including gain or loss of chromosomes. The centrosome is an organelle that governs mitotic chromosome segregation and that functions as a signaling platform downstream of the DNA damage response. Here, we review the current literature to highlight how oncoviruses induce genomic instability via the deregulation of the centrosome. Viral interference with the centrosome duplication cycle, leading to centrosome amplification, is illustrated, with a special emphasis on mechanisms shared by several viral families. In addition, we discuss how oncoviruses could alter the signaling functions of the centrosome, and we comment on the bibliographic gaps that could be addressed by future research.

SQSTM-1/p62 potentiates HTLV-1 Tax-mediated NF-κB activation through its ubiquitin binding function.

The NF-κB pathway is constitutively activated in adult T cell leukemia, an aggressive malignancy caused by Human T Leukemia Virus type 1 (HTLV-1). The viral oncoprotein Tax triggers this constitutive activation by interacting with the ubiquitin-rich IKK complex. We previously demonstrated that Optineurin and TAX1BP1, two members of the ubiquitin-binding, Sequestosome-1 (SQSTM-1/p62)-like selective autophagy receptor family, are involved in Tax-mediated NF-κB signaling. Here, using a proximity-dependent biotinylation approach (BioID), we identify p62 as a new candidate partner of Tax and confirm the interaction in infected T cells. We then demonstrate that p62 knock-out in MEF cells as well as p62 knock-down in HEK293T cells significantly reduces Tax-mediated NF-κB activity. We further show that although p62 knock-down does not alter NF-κB activation in Jurkat T cells nor in infected T cells, p62 does potentiate Tax-mediated NF-κB activity upon over-expression in Jurkat T cells. We next show that p62 associates with the Tax/IKK signalosome in cells, and identify the 170-206 domain of p62 as sufficient for the direct, ubiquitin-independent interaction with Tax. However, we observe that this domain is dispensable for modulating Tax activity in cells, and functional analysis of p62 mutants indicates that p62 could potentiate Tax activity in cells by facilitating the association of ubiquitin chains with the Tax/IKK signalosome. Altogether, our results identify p62 as a new ubiquitin-dependent modulator of Tax activity on NF-κB, further highlighting the importance of ubiquitin in the signaling activity of the viral Tax oncoprotein.