The Interactive Complex between Cytomegalovirus Kinase vCDK/pUL97 and Host Factors CDK7–Cyclin H Determines Individual Patterns of Transcription in Infected Cells

Abstract

The infection of human cytomegalovirus (HCMV) is strongly determined by the host–cell interaction in a way that the efficiency of HCMV lytic replication is dependent on the regulatory interplay between viral and cellular proteins. In particular, the activities of protein kinases, such as cyclin-dependent kinases (CDKs) and the viral CDK ortholog (vCDK/pUL97), play an important role in both viral reproduction and virus–host interaction. Very recently, we reported on the complexes formed between vCDK/pUL97, human cyclin H, and CDK7. Major hallmarks of this interplay are the interaction between cyclin H and vCDK/pUL97, which is consistently detectable across various conditions and host cell types of infection, the decrease or increase in pUL97 kinase activity resulting from cyclin H knock-down or elevated levels, respectively, and significant trans-stimulation of human CDK7 activity by pUL97 in vitro. Due to the fact that even a ternary complex of vCDK/pUL97–cyclin H–CDK7 can be detected by coimmunoprecipitation and visualized by bioinformatic structural modeling, we postulated a putative impact of the respective kinase activities on the patterns of transcription in HCMV-infected cells. Here, we undertook a first vCDK/pUL97-specific transcriptomic analysis, which combined conditions of fully lytic HCMV replication with those under specific vCDK/pUL97 or CDK7 drug-mediated inhibition or transient cyclin H knockout. The novel results were further strengthened using bioinformatic modeling of the involved multi-protein complexes. Our data underline the importance of these kinase activities for the C-terminal domain (CTD) phosphorylation-driven activation of host RNA polymerase in HCMV-infected cells. The impact of the individual experimental conditions on differentially expressed gene profiles is described in detail and discussed.

‘Getting Better’—Is It a Feasible Strategy of Broad Pan-Antiherpesviral Drug Targeting by Using the Nuclear Egress-Directed Mechanism?

“…Although the experimental proof of a direct binding of host kinases to the herpesviral core NECs has not been successful for some time, the functional studies on NEC regulation strongly substantiated this statement (see numerous reviews: [ 45 , 48 , 50 , 62 , 64 , 126 , 127 , 128 , 129 , 130 , 131 , 132 ]). It became increasingly clear that, although the association of PKC could not be directly linked with functional importance, other host and viral kinases played a very crucial role in the regulatory phosphorylation of NEC proteins [ 125 , 133 , 134 , 135 ] and nuclear lamins [ 50 , 56 , 58 ].…”