Viral hijacking of the nucleolar DNA-damage response machinery: a novel mechanism to regulate host cell biology

Abstract

Recent landmark studies indicate that nucleoli play critical roles in the DNA-damage response (DDR) via interaction of DDR machinery including NBS1 with nucleolar Treacle protein, a key mediator of ribosomal RNA (rRNA) transcription and processing, implicated in Treacher-Collins syndrome. Here, using proteomics, confocal/super-resolution imaging, and infection under BSL-4 containment, we present the first report that this nucleolar DDR pathway is targeted by infectious pathogens. We find that Treacle has antiviral activity, but that matrix protein of Henipaviruses and P3 protein of rabies virus, highly pathogenic viruses of the order Mononegavirales, interact with Treacle and inhibit its function, thereby silencing rRNA biogenesis, consistent with mimicking NBS1-Treacle interaction during a DDR. These data identify a novel mechanism for viral modulation of host cells by appropriating the nucleolar DDR; this appears to have developed independently in different viruses, and represents, to our knowledge, the first direct intra-nucleolar function for proteins of any mononegavirus.