Résumé
PML, also known as TRIM19, belongs to the family of tripartite motif (TRIM) proteins. Like some other TRIM proteins, PML exerts a broad antiviral activity. PML is mainly expressed in the nucleus, where it forms dynamic structures known as PML nuclear bodies that recruit many proteins, such as Sp100 and Daxx. It was reported that HIV-1 infection induces the translocation of PML from the nucleus to the cytoplasm (Turelli et al., 2001). This paper also suggested that PML could interfere with HIV-1 infection but this was later contradicted (Berthoux et al., 2003).
We sought to re-evaluate the implication of PML during HIV-1 infection. We show that infection by HIV-1 but also other retroviruses triggers the formation of PML cytoplasmic bodies, as early as 30min post-infection. PML re-localization was blocked by reverse-transcription inhibitors and was not observed following infection with unrelated viruses, suggesting it is specifically triggered by retroviral reverse-transcription. Furthermore, we show that PML interferes with an early step of retroviral infection since PML knockdown dramatically increases RT efficiency. However, the effect of PML on retroviral infection was found to be indirect and to operate through the stabilization of one of its well-characterized partners, Daxx. In the presence of PML, Daxx inhibits an early step of reverse-transcription thereby interfering with HIV-1 infection. Like PML, Daxx is an interferon-inducible protein that provides intrinsic immunity against various viruses. Our study unravels for the first time its capacity to inhibit an early step of HIV-1 replication.