Functional interaction of the human cytomegalovirus IE2 protein with histone deacetylase 2 in infected human fibroblasts

Abstract

In human cytomegalovirus (HCMV)-infected cells, the 86 kDa immediate-early (IE) 2 protein plays a key role in transactivating downstream viral genes. Recently, IE2 has been shown to interact with histone deacetylase 1 (HDAC1) and HDAC3. HDAC1 recruited by IE2 was required for IE2-mediated autorepression of the major IE (MIE) promoter, whereas IE2-HDAC3 interaction was suggested to relieve the repressive effect of HDAC3 on viral early promoters. However, whether IE2 indeed inhibits HDAC's deacetylation activity on viral promoters and interacts with other HDACs remains unclear. Here, we provide evidence that IE2 functionally interacts with HDAC2 and negates its repressive effect on the viral polymerase promoter. IE2 interacted with HDAC2 in both virus-infected cells and in vitro, and required the conserved C-terminal half for HDAC2 binding. The subcellular localization of HDAC2 was changed in virus-infected cells, showing colocalization with IE2 in viral transcription and replication sites. The overall HDAC2 protein levels and its deacetylation activity slightly increased during the late stages of infection and the IE2-associated deacetylation activity was still sensitive to an HDAC inhibitor, trichostatin A. In transfection assays, however, histone acetylation of the viral polymerase promoter was suppressed by HDAC2, and this was relieved by IE2 binding. Therefore, our data demonstrate that IE2 functionally interacts with HDAC2 and modulates its deacetylation activity on the viral polymerase promoter. Our results also support the idea that interactions of IE2 with several HDACs to modulate the host epigenetic regulation on viral MIE and early promoters are important events in the process of productive infection.

Human Cytomegalovirus pUL97 Regulates the Viral Major Immediate Early Promoter by Phosphorylation-Mediated Disruption of Histone Deacetylase 1 Binding

“…Park et al (36) have reported that total HDAC2 deacetylase activity decreases early during HCMV infection. We were interested in determining the impact of pUL97 kinase activity on deacetylase activity in the presence and absence of infection.…”

“…DAXX interacts with HDAC1, and together they repress transcription (33). Also, the HCMV pUL123 (IE1) protein inhibits histone deacetylation (34) and, along with pUL122 (IE2), has been shown to affect the repressive actions of HDAC1, 2, and 3 (34)(35)(36)(37). Other HCMV proteins interact with HDACs or HDACcontaining complexes, including pUL29/28, which associates with the nucleosome remodeling and deacetylase complex, NuRD, influencing both viral (25) and cellular gene expression (38).…”

Human Cytomegalovirus Early Protein pUL21a Promotes Efficient Viral DNA Synthesis and the Late Accumulation of Immediate-Early Transcripts

“…Late promoters remain largely associated with repressive chromatin marks and only begin to become acetylated starting at 24 hpi (6,16). Binding of IE2-86 to HDACs 1, 2, and 3 and multiple histone methyltransferases (HMTs) during the late stages of infection may activate transcription from late promoters (37,40,46). However, it is also possible that IE2-86 transactivates late promoters through its interactions with many other viral and cellular partners or that the late-accumulating IE2-86 is responsible for one of the many other functions attributed to this protein (65).…”

Viral epigenomes in human tumorigenesis

“…It is suggested that viral proteins target HDACs and may modulate viral and cellular gene expression (Reeves et al, 2006;SoderbergNaucier, 2006;Park et al, 2007c;Mehta et al, 2009).…”