Kaposi΄s sarcoma-associated herpesvirus ORF36 protein induces chromosome condensation and phosphorylation of histone H3.

Kaposi΄s sarcoma-associated herpesvirus (KSHV) has been known as an agent causing Kaposi΄s sarcoma, primary effusion lymphoma, and multicentric Castleman΄s disease. In the lytic phase of the virus cycle, various viral genes are expressed, which causes host cell dysregulation. Among the lytic genes, viral protein kinase (vPK) encoded by ORF36 is a member of serine/threonine protein kinase (CHPK) family, which is involved in viral gene expression, viral DNA replication and encapsidation, and nuclear egress of virions. Recent studies have shown that the BGLF4 protein of Epstein-Barr virus (EBV), a member of the CHPK family, alters the host cell chromatin structure through phosphorylation of its key regulators. The role of KSHV ORF36 in cellular mitotic events, however, is not yet understood. In the current study, we showed that KSHV ORF36 induced chromosome condensation and phosphorylation of histone H3 on Ser 10, which are known as cellular mitosis markers. These processes have occurred in a kinase activity-dependent manner.