HTLV-1 subverts the innate immune effector gene IRF7 by viral HBZ protein for oncogenesis

Le résumé fourni par la source

Interferon regulatory factors (IRFs) are innate immune transcription factors responsible for inducing the expression of type I interferons (IFN-I), which combat pathogen invasions via initiating the downstream Janus kinase signal transducer and activator of transcription (JAK-STAT) pathway. Among them, IRF7 plays a central role by forming heterodimers with IRF3 to initiate IFN-I production and is therefore frequently targeted by viruses to evade immune detection. Contrary to this common paradigm, we show that IRF7 is activated and upregulated by the retrovirus human T-cell leukemia virus type 1 (HTLV-1), via its oncoprotein HBZ. Moreover, IRF7 is highly expressed in HTLV-1 induced CD4 T-cell malignancy named adult T-cell leukemia/lymphoma (ATLL), and promotes the proliferation of infected cells both in vitro and in vivo. Intriguingly, HBZ is able to interfere with the interaction of IRF7 and IRF3, suppressing IFN-I pathway activation. On the other hand, IRF7 was found to upregulate and activate STAT5B, a transcription factor of the JAK-STAT pathway frequently mutated in hematological malignancies. Together, these findings reveal a mechanism by which HTLV-1 hijacks a critical innate immune effector to sustain persistent infection and drive oncogenesis without activating antiviral IFN-I pathway. In this work, authors show that HTLV-1 subverts the typical antiviral role of the innate immune effector protein IRF7; instead of triggering an IFN-I response, the virus uses IRF7 to promote the growth of infected cells by establishing an oncogenic IRF7-STAT5B axis via HBZ protein.

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