Analysis of the newly discovered control of HSV-1 replication by the PP2A B-type subunit PR130

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Many chemotherapeutic agents induce DNA replication stress, leading to the activation of checkpoint kinases. These control the cell cycle and genomic integrity. The applicant Krämer demonstrated that the phosphatase-2A (PP2A) B-subunit PR130/PPP2R3A controls the activation of checkpoint kinases and thus the fate of stressed cells. DNA replication stress, DNA damage, and activation of checkpoint kinases are also consequences of viral infections. Since it is unknown whether the PP2A-PR130 complex affects virus-induced checkpoint kinase activation and viral replication, we (applicants Krämer and Henke) have developed and successfully worked on a research project. Prof. Henke has been doing research on the characterization of virus-host cell interactions for more than 20 years. Our cooperation has been based on this for many years. We have entered new scientific territory on PR130. Herpes simplex virus type 1 (HSV-1) replicates its DNA genome in the nucleus. Our data show for the first time that PR130 suppresses HSV-1 replication and that PR130 regulates phosphorylation and stability of checkpoint kinases in this context. We aim to clarify the extent to which PR130 and its effects on checkpoint kinases modulate cell cycle changes and DNA repair mechanisms that are induced by HSV-1. For this, we aim to use cell systems relevant to infection events and the CRISPR-Cas9 method. In addition, we see that infection with HSV-1 reduces the expression of PR130. We want to investigate whether this is a novel mechanism that promotes viral replication. Using proteomics analyses, we would additionally like to determine which cellular and viral proteins are dephosphorylated and controlled in their stability by the PP2A-PR130 complex and how these processes determine viral replication. We will also investigate how clinically applicable modern checkpoint kinase inhibitors affect viral replication dependent on PR130. Based on further, also unpublished data, we additionally want to analyze an influence of the PP2A B-subunit B56β on HSV-1 replication. To date, no publications exist on whether PR130 and B56β influence HSV-1 replication and spread. Therefore, our analyses will significantly extend the existing data. The clinical relevance of the planned research project stems from the fact that HSV-1 is prevalent worldwide. The WHO estimates that in 2016, approximately 3.7 billion people under the age of 50 had HSV-1 infection, with a global prevalence of 66.6% and an increasing development of resistance to applied anti-viral drugs. Therefore, our planned project based on host cell targeted therapy has a potentially high socio-economic and socio-political value.