casein-kinase-ii and Papillomavirus-Infections

Bromodomain-containing protein 4 (Brd4) is a cellular chromatin-binding factor and transcriptional regulator that recruits sequence-specific transcription factors and chromatin modulators to control target gene transcription. Papillomaviruses (PVs) have evolved to hijack Brd4's activity in order to create a facilitating environment for the viral life cycle. Brd4, in association with the major viral regulatory protein E2, is involved in multiple steps of the PV life cycle including replication initiation, viral gene transcription, and viral genome segregation and maintenance. Phosphorylation of Brd4, regulated by casein kinase II (CK2) and protein phosphatase 2A (PP2A), is critical for viral gene transcription as well as E1- and E2-dependent origin replication. Thus, pharmacological agents regulating Brd4 phosphorylation and inhibitors blocking phospho-Brd4 functions are promising candidates for therapeutic intervention in treating human papillomavirus (HPV) infections as well as associated disease.

Topics: Carcinogenesis; Casein Kinase II; Cell Cycle Proteins; DNA-Binding Proteins; Gene Expression Regulation; Host-Pathogen Interactions; Humans; Keratinocytes; Nuclear Proteins; Oncogene Proteins, Viral; Papillomaviridae; Papillomavirus Infections; Phosphorylation; Protein Phosphatase 2; Signal Transduction; Skin Neoplasms; Transcription Factors; Transcription, Genetic; Virus Replication

Inhibition of human papillomavirus (HPV) replication is a promising therapeutic approach for intervening with HPV-related pathologies. Primary targets for interference are two viral proteins, E1 and E2, which are required for HPV replication. Both E1 and E2 are phosphoproteins; thus, the protein kinases that phosphorylate them might represent secondary targets to achieve inhibition of HPV replication. In the present study, we show that CX4945, an ATP-competitive small molecule inhibitor of casein kinase 2 (CK2) catalytic activity, suppresses replication of different HPV types, including novel HPV5NLuc, HPV11NLuc and HPV18NLuc marker genomes, but enhances the replication of HPV16 and HPV31. We further corroborate our findings using short interfering RNA (siRNA)-mediated knockdown of CK2 α and α' subunits in U2OS and CIN612 cells; we show that while both subunits are expressed in these cell lines, CK2α is required for HPV replication, but CK2α' is not. Furthermore, we demonstrate that CK2α acts in a kinase activity-dependent manner and regulates the stability and nuclear retention of endogenous E1 proteins of HPV11 and HPV18. This unique feature of CK2α makes it an attractive target for developing antiviral agents.

Topics: Bone Neoplasms; Casein Kinase II; Humans; Osteosarcoma; Papillomaviridae; Papillomavirus Infections; Phosphoproteins; Phosphorylation; Tumor Cells, Cultured; Viral Proteins

The bovine papillomavirus E1 helicase is essential for viral replication. In dividing cells, DNA replication maintains, but does not increase, the viral genome copy number. Replication is limited by low E1 expression and an E1 nucleocytoplasmic shuttling mechanism. Shuttling is controlled in part by phosphorylation of E1 by cellular kinases. Here we investigate conserved sites for phosphorylation by kinase CK2 within the E1 nuclear localization signal. When these CK2 sites are mutated to either alanine or aspartic acid, no change in replication phenotype is observed, and there is no effect on the subcellular distribution of E1, which remains primarily nuclear. This demonstrates that phosphorylation of E1 by CK2 at these sites is not a factor in regulating viral DNA replication in dividing cells.

Topics: Amino Acid Sequence; Animals; Bovine papillomavirus 1; Casein Kinase II; Cattle; Cattle Diseases; Cell Nucleus; DNA-Binding Proteins; Molecular Sequence Data; Nuclear Localization Signals; Papillomavirus Infections; Phosphorylation; Protein Transport; Viral Proteins

Infection by human papillomavirus type 16 (HPV-16) is the cause of 50% or more of cervical cancers in women. The E7 oncoprotein of HPV-16 has long been known as a potent immortalizing and transforming agent. We used different servers like PseAAC, MHC_binding, MHC_II_binding and Expasy for the present computational prediction. The results for T cell epitopes showed that B1501, A0203, A0201, A0202, A6801 and DRB0405 alleles had lower IC50 than other alleles. We also predicted several peptides with the best binding affinities for alleles of the most frequent MHC class I and II alleles of the various ethnic groups living in the different region of Iran. Two peptides (26-35) and (44-52) were predicted as B-cell epitopes. According to this analysis 1 N-glycosylation site, 2 PKC sites, 4 CK2 sites and 3 disulfide sites were predicted. Our computational study predicted that B cell epitope 1 was Casein kinase II phosphorylated (site No. 31) and glycosylated (site No. 29). Putative MHC-I epitopes 3 and 5 and MHC-II epitopes 19, 21 and 26 were predicted to be casein kinase II phosphorylated. MHC-II epitopes 19 and 21 was predicted to be glycosylated. T cell epitopes 1, 13, 16 and 24 were demonstrated to be kinase C phosphorylated. The result of this analysis for Iranian HPV-16 E7 also indicated that 21.43%, 18.37% and 60.20% of the protein were in the α-helix, extended strand and random coil respectively.

Topics: Alleles; B-Lymphocytes; Casein Kinase II; Computational Biology; Epitopes; Ethnicity; Female; Glycosylation; Humans; Image Processing, Computer-Assisted; Inhibitory Concentration 50; Iran; Major Histocompatibility Complex; Papillomavirus E7 Proteins; Papillomavirus Infections; Peptides; Phosphorylation; Protein Binding; Protein Kinase C; Protein Structure, Secondary; T-Lymphocytes; Uterine Cervical Neoplasms