PCNA Confers the Conversion of Hepatitis B Virus Relaxed Circular DNA to Covalently Closed Circular DNA by Its DNA Binding Domain / 中国生物化学与分子生物学报

Chronic hepatitis B virus (HBV) infection is a primary cause for liver cancer. And the main challenge of curing hepatitis B is the elimination of the stable covalently closed circular DNA (cccDNA) of the viral genome. The formation of HBV cccDNA requires the filling of single-stranded region and the ligation of nicks in relaxed circular DNA (rcDNA) strands. Previously, our group reported that proliferating cell nuclear antigen (PCNA) was involved in the formation of HBV cccDNA. However, the underlying mechanism of the conversion of HBV rcDNA to cccDNA is poorly understood. In the present study, we aim to explore the mechanism by which PCNA contributes to the conversion of HBV rcDNA to cccDNA. Our data showed that PCNA was involved in the process of HBV rcDNA repair. The knockout of PCNA by the CRISPR/Cas9 system remarkably blocked the conversion of HBV rcDNA to cccDNA, while the ectopic expression of PCNA could effectively rescue the event (P<0. 001). Knockout of PCNA significantly slowed down the conversion kinetics of HBV rcDNA to cccDNA (P<0. 01). Mechanically, the DNA binding domain of PCNA was required for the process of HBV rcDNA repair to cccDNA (P<0. 01). Thus, we conclude that PCNA confers the conversion of HBV rcDNA to cccDNA by its DNA binding domain. Clinically, PCNA might serve as a novel target for antiviral therapy.

Advances on anti-neoplastic STAT3 inhibitors / 药学学报

Signal transducer and activator of transcription 3 (STAT3) is a kind of signal transduction protein involved in cell proliferation, differentiation, apoptosis and other important physiological processes in response to a large number of cytokines and growth factors in cells. It has been shown that constitutive activation of STAT3 is closely associated with oncogenesis and tumorigenesis. Inhibition of aberrant STAT3 signaling has been one of promising strategies for the development of anti-neoplastic therapeutics. The review summarizes the latest progress of STAT3 inhibitors in recent years from the perspective of targeting N-terminal domain, DNA binding domain, SH2 domain and C-terminal transactivation domain of STAT3.

Research Progress of the Relationship between the Expression of TAR DNA-binding Domain Protein 43 and Brain Injury / 法医学杂志

TAR DNA-binding domain protein 43 （TDP-43） is a highly conserved and widely expressed nuclear protein. Nowadays, the expression of TDP-43 can be found in most neurodegenerative diseases such as Alzheimer's disease, which makes it become a neurodegenerative disease associated marker protein. From the current research status at homeland and abroad, and around the relationship between the expression of TDP-43 and brain injury, this article emphatically probes into the specific expression and function of TDP-43 in acute and chronic brain injury based on the knowledge of its biological characteristics, which aims to explore the feasibility for determining the cause of death and the injury and disability situations by TDP-43 in forensic pathology.

Assessing protein stability of the dimeric DNA-binding domain of E2 human papillomavirus 18 with molecular dynamics

The objective of this study is to understand the structural flexibility and curvature of the E2 protein of human papillomavirus type 18 using molecular dynamics (6 ns). E2 is required for viral DNA replication and its disruption could be an anti-viral strategy. E2 is a dimer, with each monomer folding into a stable open-faced â-sandwich. We calculated the mobility of the E2 dimer and found that it was asymmetric. These different mobilities of E2 monomers suggest that drugs or vaccines could be targeted to the interface between the two monomers.

Interferon consensus sequence binding protein: Not essential for interferon alpha-mediated antiviral response to vesicular-stomatitis virus infection in HL-60 cells

BACKGROUND: The role of the interferon consensus sequence binding protein (ICSBP), a member of interferon regulatory factor family, in protecting against a vesicular stomatitis virus (VSV) infection has not been firmly elucidated. Thus, it was investigated utilizing the human promyelocytic leukemia HL-60 cells which do not express ICSBP. METHODS: HL-60 cells were stably transfected with plasmid containing cDNA for either ICSBP or DNA binding domain (DBD) and tested for their VSV-susceptibilities. The susceptibility of each transfectant group to a VSV infection was determined by a plaque assay at 1 h, 24 h, and 48 h post-infection in the presence (500 IU/ml) or absence of interferon alpha(IFN alpha). RESULTS: In the absence of IFN alpha, the three groups showed similar sensitivities to a VSV infection. However, when pre-treated with IFN, the viral titers in both the ICSBP and control clones steadily decreased over 48 h of incubation, indicating the existence of IFN alpha-mediated protection against VSV infection. The IFN alpha-treated ICSBP clones appeared to be more resistant to infection compared with the control clones, although the difference was not great . On the contrary, the viral titers in the IFN alpha-treated DBD clones increased at 24 h then decreased by 48 h. CONCLUSION: The expression of truncated ICSBP (DBD) does not appear to underlie the impaired protection against a VSV infection in the DBD clones, since even the control clones lacking ICSBP were protected from a VSV infection. This suggests that ICSBP does not play a critical role in the IFN alpha-mediated anti-VSV response of HL-60 cells, although it appears to confer some resistance to a VSV infection.