2’,3’-Cyclic Nucleotide 3’-Phosphodiesterases Inhibit Hepatitis B Virus Replication

Hui Ma,Qin Wang,Lai Wei,Lin Zhu,Xing-Wang Xie,Xue-Yan Wang,Xiao-Ben Pan,Wen-Li Guan,Jin-Chao Han,Xing-Liang Zhao,Wenyu Lin

doi:10.1371/journal.pone.0080769

Abstract

2’,3’-cyclic nucleotide 3’-phosphodiesterase (CNP) is a member of the interferon-stimulated genes, which includes isoforms CNP1 and CNP2. CNP1 is locally expressed in the myelin sheath but CNP2 is additionally expressed at low levels outside the nervous system. CNPs regulate multiple cellular functions and suppress protein production by association with polyadenylation of mRNA. Polyadenylation of Hepatitis B virus (HBV) RNAs is crucial for HBV replication. Whether CNPs interact with polyadenylation signal of HBV RNAs and interfere HBV replication is unknown. In this study, we evaluated expressions of CNP isoforms in hepatoma cell lines and their effects on HBV replication. We found that CNP2 is moderately expressed and gently responded to interferon treatment in HepG2, but not in Huh7 cells. The CNP1 and CNP2 potently inhibited HBV production by blocking viral proteins synthesis and reducing viral RNAs, respectively. In chronic hepatitis B patients, CNP was expressed in most of HBV-infected hepatocytes of liver specimens. Knockdown of CNP expression moderately improved viral production in the HepG2.2.15 cells treated with IFN-α. In conclusion, CNP might be a mediator of interferon-induced response against HBV.

Highlights

The 2’, 3’-cyclic nucleotide 3’-phosphodiesterase (CNP) belongs to the 2H phosphoesterase superfamily, which is characterized by the presence of two conserved HxT/Sx motifs (x denoting a hydrophobic residue) in the active site [1]
Since CNP1 mRNA can not be differentiated from the CNP2 mRNA by PCR, we amplified the total CNP by reverse primers (Table 1) recognizing a shared region by both CNP1 and CNP2
Interferons restrict the replication of Hepatitis B virus (HBV) by inducing the expression of interferon-stimulated genes (ISGs) that can result in the resolution of the chronic HBV infection [30,31,32,33,34,35,36]

Summary

Introduction

The 2’, 3’-cyclic nucleotide 3’-phosphodiesterase (CNP) belongs to the 2H phosphoesterase superfamily, which is characterized by the presence of two conserved HxT/Sx motifs (x denoting a hydrophobic residue) in the active site [1]. CNP contains an N-terminal domain that is distantly related to the Ploop containing nucleoside triphosphate hydrolases. The Nterminal domain is involved in CNP dimerization and direct interaction with the calcium sensor calmodulin [2,3]. The Cterminus is a phosphodiesterase domain, which catalyzes the formation of 2’-nucleotide products from 2’,3’-cyclic substrates [4,5]. The activity of phosphodiesterase plays a key role in tRNA splicing in yeast. The substrate for CNP and its role in the life of mammals is unknown [8]

Methods

Results

Conclusion