Dihydromyricetin Alleviates H9C2 Cell Apoptosis and Autophagy by Regulating CircHIPK3 Expression and PI3K/AKT/mTOR Pathway.

OBJECTIVE: To investigate the effect and potential mechanism of dihydromyricetin (Dmy) on H9C2 cell proliferation, apoptosis, and autophagy. METHODS: H9C2 cells were randomly divided into 7 groups, namely control, model, EV (empty pCDH-CMV-MCS-EF1-CopGFP-T2A-Puro vector), IV (circHIPK3 interference), Dmy (50 µ mol/L), Dmy+IV, and Dmy+EV groups. Cell proliferation and apoptosis were detected by cell counting kit-8 assay and flow cytometry, respectivley. Western blot was used to evaluate the levels of light chain 3 II/I (LC3II/I), phospho-phosphoinositide 3-kinase (p-PI3K), protein kinase B (p-AKT), and phospho-mammalian target of rapamycin (p-mTOR). The level of circHIPK3 was determined using reverse transcriptase polymerase chain reaction. Electron microscopy was used to observe autophagosomes in H9C2 cells. RESULTS: Compared to H9C2 cells, the expression of circHIPK in H9C2 hypoxia model cells increased significantly (P<0.05). Compared to the control group, the cell apoptosis and autophagosomes increased, cell proliferation rate decreased significantly, and the expression of LC3 II/I significantly increased (all P<0.05). Compared to the model group, the rate of apoptosis and autophagosomes in IV, Dmy, and Dmy+IV group decreased, the cell proliferation rate increased, and the expression of LC3 II/I decreased significantly (all P<0.05). Compared to the control group, the expressions of p-PI3K, p-AKT, and p-mTOR in the model group significantly reduced (P<0.05), whereas after treatment with Dmy and sh-circHIPK3, the above situation was reversed (P<0.05). CONCLUSION: Dmy plays a protective role in H9C2 cells by inhibiting circHIPK expression and cell apoptosis and autophagy, and the mechanism may be related to PI3K/AKT/mTOR pathway.

Successful establishment and evaluation of a new animal model for studying the hepatitis B virus YVDD mutant.

The treatment of infection with lamivudine-resistant mutants of hepatitis B virus (HBV) with mutations in the YMDD motif has become a crucial issue in the clinic. In this work, the plasmids pcDNA3.1 (+)-HBV/C-YVDD and pcDNA3.1 (+)-HBV/C-YMDD were constructed and injected into BALB/c mice using a hydrodynamics-based procedure to investigate viral replication and expression of HBV lamivudine-resistant YVDD mutants in vivo. Compared with the YMDD group, HBsAg levels were higher in sera of mice in the YVDD group, but HBeAg levels were lower on day 1 after injection. Levels of HBcAg in hepatocytes were higher in the YVDD group on day 1, whereas the HBsAg levels were lower. The levels of HBV mRNA in the liver were higher in mice in the YVDD group on day 1 after injection. The results showed that injection with these plasmids resulted in efficient initiation of replication of HBV in mice and also suggested that the combined mutations in YVDD mutants could affect the replication process.

Differential inhibition of lamivudine-resistant hepatitis B virus by allele-specific RNAi.

Drug-resistant hepatitis B virus (HBV) is a serious problem affecting antiviral therapy. In this study, two long-term eukaryotic cell lines with full-length HBV were constructed and contained either lamivudine-resistant mutants (HBV-YIDD) or wild-type virus (HBV-wt). High levels of intracellular viral DNA replication were observed continuously after transfecting the plasmids into HepG2 cells, and HBV surface antigen (HBsAg) and HBV e antigen (HBeAg) were secreted into the cell culture supernatant. A series of experiments showed differential inhibition of HBV gene expression and replication by four specific siRNAs, according to the principles of allele-specific RNAi technology. The results showed that the designed siRNAs with a mismatch in the sixteenth nucleotide of the guide strands could effectively discriminate the HBV-YIDD mutants from the wild-type alleles, thus providing a new insight into the development of antiviral therapy with differing or complementary patterns characteristic of lamivudine-resistant HBV.