SPOP inhibits HBV transcription and replication by ubiquitination and degradation of HNF1α.

Hepatitis B virus (HBV) infection remains a significant public health burden worldwide. The persistence of covalently closed circular DNA (cccDNA) within the nucleus of infected hepatocytes is responsible for the failure of antiviral treatments. The ubiquitin proteasome system (UPS) has emerged as a promising antiviral target, as it can regulate HBV replication by promoting critical protein degradation in steps of viral life cycle. Speckle-type POZ protein (SPOP) is a critical adaptor for Cul3-RBX1 E3 ubiquitin ligase complex, but the effect of SPOP on HBV replication is less known. Here, we identified SPOP as a novel host antiviral factor against HBV infection. SPOP overexpression significantly inhibited the transcriptional activity of HBV cccDNA without affecting cccDNA level in HBV-infected HepG2-NTCP and primary human hepatocyte cells. Mechanism studies showed that SPOP interacted with hepatocyte nuclear factor 1α (HNF1α), and induced HNF1α degradation through host UPS pathway. Moreover, the antiviral role of SPOP was also confirmed in vivo. Together, our findings reveal that SPOP is a novel host factor which inhibits HBV transcription and replication by ubiquitination and degradation of HNF1α, providing a potential therapeutic strategy for the treatment of HBV infection.

Biodegradable cotton fiber-based piezoresistive textiles for wearable biomonitoring.

Electronic textiles are fundamentally changing the way we live. However, the inability to effectively recycle them is a considerable burden to the environment. In this study, we developed a cotton fiber-based piezoresistive textile (CF p-textile) for biomonitoring which is biocompatible, biodegradable, and environmentally friendly. These CF p-textiles were fabricated using a scalable dip-coating method to adhere MXene flakes to porous cotton cellulose fibers. The adhesion is made stronger by strong hydrogen bonding between MXene flakes and hierarchically porous cotton cellulose fibers. This cotton-fiber system provides a high sensitivity of 17.73 kPa-1 in a wide pressure range (100 Pa-30 kPa), a 2 Pa subtle pressure detection limit, fast response/recovery time (80/40 ms), and good cycle stability (over 5, 000 cycles). With its compelling sensing performance, the CF p-textile can detect various human biomechanical activities, including pulsation, muscle movement, and swallowing, while still being comfortable to wear. Moreover, the cotton cellulose is decomposed into low-molecular weight cellulose or glucose as a result of the 1,4-glycosidic bond breakage when exposed to acid or during natural degradation, which allows the electronic textile to be biodegradable. This work offers an ecologically-benign, cost-effective and facile approach to fabricating high-performance wearable bioelectronics.

CK1α upregulates the IFNAR1 expression to prompt the anti-HBV effect of type I IFN in hepatoma carcinoma cells.

Casein kinase 1α (CK1α) mediates the phosphorylation and degradation of interferon-α/ß receptor 1 (IFNAR1) in response to viral infection. However, how CK1α regulates hepatitis B virus (HBV) replication and the anti-HBV effects of IFN-α are less reported. Here we show that CK1α can interact with IFNAR1 in hepatoma carcinoma cells and increased the abundance of IFNAR1 by reducing the ubiquitination levels in the presence of HBV. Furthermore, CK1α promotes the IFN-α triggered JAK-STAT signaling pathway and consequently enhances the antiviral effects of IFN-α against HBV replication. Our results collectively provide evidence that CK1α positively regulates the anti-HBV activity of IFN-α in hepatoma carcinoma cells, which would be a promising therapeutic target to improve the effectiveness of IFN-α therapy to cure CHB.

Quantification of intrahepatic cccDNA in HBV associated hepatocellular carcinoma by improved ddPCR method.

The quantification of intrahepatic covalently closed circular DNA (cccDNA) is important for assessing the efficiency of anti-HBV therapy. Exonuclease treatment is essential before real-time quantitative PCR (qPCR) or droplet digital PCR (ddPCR) measurement to improve the specificity of cccDNA quantification. In this research, we compared the limit of detection (LOD) of qPCR and ddPCR and evaluated the digestion efficiency of three exonuclease treatments, PSAD, exonuclease III and T5 exonuclease, when measuring cccDNA in cells or clinical samples by ddPCR. We demonstrated that the LOD of ddCPR was 5.9 copies/reaction, which was much lower than that of qPCR (54.9 copies/reaction), indicating that ddPCR is more sensitive than qPCR. Meanwhile, compared to PSAD or Exo III, UNG and T5 exonuclease treatment combined with ddPCR is more effective in detecting intrahepatic cccDNA in clinical samples. Finally, the median intrahepatic cccDNA was 2.6 copies/104 cells in 26 pairs of HCC samples determined by the improved ddPCR method. Therefore, we developed an optimized ddPCR method, which can be used for the absolute quantification of low levels of intrahepatic cccDNA more precisely.

Role of the long non-coding RNA LINC00052 in tumors.

Long intergenic non-protein coding RNA 52 (LINC00052) is a non-coding RNA with >200 nucleotides in length, which exerts important effects on several physiological and pathological processes of the human body. Recent studies have demonstrated that LINC00052 plays key roles in the tumorigenesis, progression and metastasis of multiple types of human cancer, including hepatocellular carcinoma, breast cancer, colorectal cancer, cervical carcinoma and gastric cancer. However, the associations between LINC00052 and these tumors remain unclear. The present review summarizes the biological functions of LINC00052 during the pathogenic process of certain tumors, and discusses its potential therapeutic targets.

A Peptide-Based Magnetic Chemiluminescence Enzyme Immunoassay for Serological Diagnosis of Coronavirus Disease 2019.

BACKGROUND: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a novel ß-coronavirus, causes severe pneumonia and has spread throughout the globe rapidly. The disease associated with SARS-CoV-2 infection is named coronavirus disease 2019 (COVID-19). To date, real-time reverse-transcription polymerase chain reaction (RT-PCR) is the only test able to confirm this infection. However, the accuracy of RT-PCR depends on several factors; variations in these factors might significantly lower the sensitivity of detection. METHODS: In this study, we developed a peptide-based luminescent immunoassay that detected immunoglobulin (Ig)G and IgM. The assay cutoff value was determined by evaluating the sera from healthy and infected patients for pathogens other than SARS-CoV-2. RESULTS: To evaluate assay performance, we detected IgG and IgM in the sera from confirmed patients. The positive rate of IgG and IgM was 71.4% and 57.2%, respectively. CONCLUSIONS: Therefore, combining our immunoassay with real-time RT-PCR might enhance the diagnostic accuracy of COVID-19.

DHX9 interacts with APOBEC3B and attenuates the anti-HBV effect of APOBEC3B.

Hepatitis B virus (HBV) is a partially double-stranded DNA virus that replicates by reverse transcription. We previously demonstrated that the host restriction factor-APOBEC3B (A3B) inhibited HBV replication which was dependent on its deaminase activity during reverse transcription. However, the host factors involved in the process of regulating the anti-HBV function of A3B are less known. In this research, to obtain a comprehensive understanding of the interaction networks of A3B, we conducted coimmunoprecipitation and mass spectrometry to identify A3B-interacting proteins in the presence of HBV. By this approach, we determined that DExD/H-box helicase 9 (DHX9) suppressed the anti-HBV effect of A3B, and this suppression was dependent on their interaction. Although DHX9 did not affect the deamination activity of A3B in vitro assay or the viral DNA editing of A3B in HepG2-NTCP cells that support HBV infection, it inhibited the binding of A3B with pgRNA. These data suggest that DHX9 can interact with A3B and attenuate the anti-HBV efficacy of A3B.Abbreviations: 3D-PCR: differential DNA denaturation PCR; APOBEC3: apolipoprotein B mRNA-editing catalytic polypeptide 3; cccDNA: covalently closed circular DNA; co-IP: coimmunoprecipitation; DDX: DExD-box RNA helicases; HBc: HBV core protein; HBV: hepatitis B virus; HepAD38: HepG2 cell line stably transfected with HBV DNA; HepG2-NTCP: HepG2 cell line stably transfected with Na+/taurocholate cotransporter polypeptide; Huh7: human hepatoma cell line; pgRNA: pregenomic RNA; PPI: protein-protein interactions; RC DNA: relaxed circular DNA.

Hepatitis B virus X protein modulates upregulation of DHX9 to promote viral DNA replication.

Hepatitis B virus (HBV) infection is a major cause of acute and chronic liver diseases. During the HBV life cycle, HBV hijacks various host factors to assist viral replication. In this research, we find that the HBV regulatory protein X (HBx) can induce the upregulation of DExH-box RNA helicase 9 (DHX9) expression by repressing proteasome-dependent degradation mediated by MDM2. Furthermore, we demonstrate that DHX9 contributes to viral DNA replication in dependence on its helicase activity and nuclear localization. In addition, the promotion of viral DNA replication by DHX9 is dependent on its interaction with Nup98. Our findings reveal that HBx-mediated DHX9 upregulation is essential for HBV DNA replication.

Cyclin E2-CDK2 mediates SAMHD1 phosphorylation to abrogate its restriction of HBV replication in hepatoma cells.

SAMHD1 inhibits Hepatitis B virus (HBV) replication by reducing the intracellular dNTP levels. However, how SAMHD1 phosphorylation is regulated to abrogate its restriction of HBV replication in hepatoma cells is poorly understood. Here, we show that HBV replication and SAMHD1 phosphorylation levels are significantly reduced by knocking down cyclin-dependent kinase (CDK) 2 expression or in the presence of a CDK2 inhibitor. SAMHD1 binds to CDK2 in hepatocarcinoma cells, and this interaction does not require the HBV core protein. Furthermore, cyclin E2 participates in regulating viral replication through the CDK2/SAMHD1 phosphorylation pathway in an HBV infection system. Collectively, our results provide evidence that CDK2 has a greater role in regulating SAMHD1 phosphorylation and HBV replication than CDK1 or CDK6.

APOBEC3B edits HBV DNA and inhibits HBV replication during reverse transcription.

Hepatitis B virus is a partially double-stranded DNA virus that replicates by reverse transcription, which occurs within viral core particles in the cytoplasm. The cytidine deaminase APOBEC3B is a cellular restriction factor for HBV. Recently, it was reported that APOBEC3B can edit HBV cccDNA in the nucleus, causing its degradation. However, whether and how it can edit HBV core-associated DNAs during reverse transcription is unclear. Our studies to address this question revealed the following: First, silencing endogenous APOBEC3B in an HBV infection system lead to upregulation of HBV replication. Second, APOBEC3B can inhibit replication of HBV isolates from genotypes (gt) A, B, C, and D as determined by employing transfection of plasmids expressing isolates from four different HBV genotypes. For HBV inhibition, APOBEC3B-mediated inhibition of replication primarily depends on the C-terminal active site of APOBEC3B. In addition, employing the HBV RNaseH-deficient D702A mutant and a polymerase-deficient YMHA mutant, we demonstrated that APOBEC3B can edit both the HBV minus- and plus-strand DNAs, but not the pregenomic RNA in core particles. Furthermore, we found by co-immunoprecipitation assays that APOBEC3B can interact with HBV core protein in an RNA-dependent manner. Our results provide evidence that APOBEC3B can interact with HBV core protein and edit HBV DNAs during reverse transcription. These data suggest that APOBEC3B exerts multifaceted antiviral effects against HBV.

Association of Hepatitis B Virus Covalently Closed Circular DNA and Human APOBEC3B in Hepatitis B Virus-Related Hepatocellular Carcinoma.

Chronic Hepatitis B Virus (HBV) infections can progresses to liver cirrhosis and hepatocellular carcinoma (HCC). The HBV covalently-closed circular DNA cccDNA is a key to HBV persistence, and its degradation can be induced by the cellular deaminase APOBEC3. This study aimed to measure the distribution of intrahepatic cccDNA levels and evaluate the association between levels of cccDNA and APOBEC3 in HCC patients. Among 49 HCC patients, 35 matched cancerous and contiguous noncancerous liver tissues had detectable cccDNA, and the median intrahepatic cccDNA in the cancerous tissues (CT) was significantly lower than in the contiguous noncancerous tissues (CNCT) (p = 0.0033). RCA (rolling circle amplification), followed by 3D-PCR identified positive amplification in 27 matched HCC patients. Sequence analysis indicated G to A mutations accumulated to higher levels in CT samples compared to CNCT samples, and the dinucleotide context showed preferred editing in the GpA context. Among 7 APOBEC3 genes, APOBEC3B was the only one up-regulated in cancerous tissues both at the transcriptional and protein levels (p < 0.05). This implies APOBEC3B may contribute to cccDNA editing and subsequent degradation in cancerous tissues.