Human Cytomegalovirus Protein pp71 Displaces the Chromatin-Associated Factor ATRX from Nuclear Domain 10 at Early Stages of Infection

Abstract

The human cytomegalovirus (HCMV) tegument protein pp71, encoded by gene UL82, stimulates viral immediate-early (IE) transcription. pp71 interacts with the cellular protein hDaxx at nuclear domain 10 (ND10) sites, resulting in the reversal of hDaxx-mediated repression of viral transcription. We demonstrate that pp71 displaces an hDaxx-binding protein, ATRX, from ND10 prior to any detectable effects on hDaxx itself and that this event contributes to the role of pp71 in alleviating repression. Introduction of pp71 into cells by transfection, infection with a pp71-expressing herpes simplex virus type 1 vector, or by generation of transformed cell lines promoted the rapid relocation of ATRX from ND10 to the nucleoplasm without alteration of hDaxx levels or localization. A pp71 mutant protein unable to interact with hDaxx did not affect the intranuclear distribution of ATRX. Infection with HCMV at a high multiplicity of infection resulted in rapid displacement of ATRX from ND10, the effect being observed maximally by 2 h after adsorption, whereas infection with the UL82-null HCMV mutant ADsubUL82 did not affect ATRX localization even at 7 h postinfection. Cell lines depleted of ATRX by transduction with shRNA-expressing lentiviruses supported increased IE gene expression and virus replication after infection with ADsubUL82, demonstrating that ATRX has a role in repressing IE transcription. The results show that ATRX, in addition to hDaxx, is a component of cellular intrinsic defenses that limit HCMV IE transcription and that displacement of ATRX from ND10 by pp71 is important for the efficient initiation of viral gene expression.

PML isoforms I and II participate in PML-dependent restriction of HSV-1 replication

“…There is increasing evidence that several ND10 components contribute to intrinsic cellular resistance to a variety of herpesvirus infections (Cantrell and Bresnahan, 2006;Everett et al, 2008a;Kyratsous and Silverstein, 2009;Ling et al, 2008;Lukashchuk et al, 2008;Lukashchuk et al, 2010;Negorev et al, 2006;Preston and Nicholl, 2006;Saffert and Kalejta, 2006;Tavalai et al, 2006;Tavalai et al, 2008;Woodhall et al, 2006). We have shown that depletion of PML increases the replication efficiency of ICP0-null mutant HSV-1 (Everett et al, 2008a;Everett et al, 2006;Everett et al, 2008b), a finding that implicates PML in a repression mechanism that targets HSV-1 genomes and which is inactivated by ICP0 during the course of a wild-type virus infection.…”

Nucleosome-depleted chromatin gaps recruit assembly factors for the H3.3 histone variant

“…The homologous ATRX remodeler contains an ADD (ATRX-DNMT3-DNMT3L) domain that can bind DNA or histone tails (16)(17)(18). Indeed, ATRX is recruited to the genomes of DNA viruses as they enter the nucleus, suggesting that it may directly bind exposed DNA (19). A recent study has shown that the mammalian Hira chaperone may also directly bind exposed DNA at chromatin gaps (20).…”

Herpes simplex viral-vector design for efficient transduction of nonneuronal cells without cytotoxicity

“…However, it is well-known that pp71 degrades a chromatin-remodeling factor, hDaxx, followed by disruption of the hDaxx-ATRX complex (36,37) and members of the retinoblastoma tumor-suppressor family of proteins (38). The disruption of the hDaxx-ATRX complex can cause genomic instability (39) whereas the loss of retinoblastoma family proteins dysregulates normal cell-cycle progression (40,41).…”