| Autor: |
Pan TC; Institute of Biochemistry and Molecular Biology, College of Medicine , National Taiwan University , Taipei 10051 , Taiwan., Lo CW; Institute of Biochemistry and Molecular Biology, College of Medicine , National Taiwan University , Taipei 10051 , Taiwan., Chong WM; Institute of Atomic and Molecular Sciences , Academia Sinica , Taipei 10617 , Taiwan., Tsai CN; Institute of Biochemistry and Molecular Biology, College of Medicine , National Taiwan University , Taipei 10051 , Taiwan., Lee KY; Institute of Biochemistry and Molecular Biology, College of Medicine , National Taiwan University , Taipei 10051 , Taiwan., Chen PY; Institute of Biochemistry and Molecular Biology, College of Medicine , National Taiwan University , Taipei 10051 , Taiwan., Liao JC; Institute of Atomic and Molecular Sciences , Academia Sinica , Taipei 10617 , Taiwan., Yu MJ; Institute of Biochemistry and Molecular Biology, College of Medicine , National Taiwan University , Taipei 10051 , Taiwan. |
| Abstrakt: |
Protein phosphorylation is a reversible post-translational modification that regulates many biological processes in almost all living forms. In the case of the hepatitis C virus (HCV), the nonstructural protein 5A (NS5A) is believed to transit between hypo- and hyper-phosphorylated forms that interact with host proteins to execute different functions; however, little was known about the proteins that bind either form of NS5A. Here, we generated two high-quality antibodies specific to serine 235 nonphosphorylated hypo- vs serine 235 phosphorylated (pS235) hyper-phosphorylated form of NS5A and for the first time segregated these two forms of NS5A plus their interacting proteins for dimethyl-labeling based proteomics. We identified 629 proteins, of which 238 were quantified in three replicates. Bioinformatics showed 46 proteins that preferentially bind hypo-phosphorylated NS5A are involved in antiviral response and another 46 proteins that bind pS235 hyper-phosphorylated NS5A are involved in liver cancer progression. We further identified a DNA-dependent kinase (DNA-PK) that binds hypo-phosphorylated NS5A. Inhibition of DNA-PK with an inhibitor or via gene-specific knockdown significantly reduced S232 phosphorylation and NS5A hyper-phosphorylation. Because S232 phosphorylation initiates sequential S232/S235/S238 phosphorylation leading to NS5A hyper-phosphorylation, we identified a new protein kinase that regulates a delicate balance of NS5A between hypo- and hyper-phosphorylation states, respectively, involved in host antiviral responses and liver cancer progression. |
