Anti-aging Effects of Alu Antisense RNA on Human Fibroblast Senescence Through the MEK-ERK Pathway Mediated by KIF15

Objective:To investigate whether human short interspersed nuclear element antisense RNA(Alu antisense RNA;Alu asRNA)could delay human fibroblast senescence and explore the underlying mechanisms.Methods:We transfected Alu asRNA into senescent human fibroblasts and used cell counting kit-8(CCK-8),reactive oxygen species(ROS),and senescence-associated beta-galactosidase(SA-β-gal)staining methods to analyze the anti-aging effects of Alu asRNA on the fibroblasts.We also used an RNA-sequencing(RNA-seq)method to investigate the Alu asRNA-specific mechanisms of anti-aging.We examined the effects of KIF15 on the anti-aging role induced by Alu asRNA.We also investigated the mechanisms underlying a KIF15-induced proliferation of senescent human fibroblasts.Results:The CCK-8,ROS and SA-β-gal results showed that Alu asRNA could delay fibroblast aging.RNA-seq showed 183 differentially expressed genes(DEGs)in Alu asRNA transfected fibroblasts compared with fibroblasts transfected with the calcium phosphate transfection(CPT)reagent.The KEGG analysis showed that the cell cycle pathway was significantly enriched in the DEGs in fibroblasts transfected with Alu asRNA compared with fibroblasts transfected with the CPT reagent.Notably,Alu asRNA promoted the KIF15 expression and activated the MEK-ERK signaling pathway.Conclusion:Our results suggest that Alu asRNA could promote senescent fibroblast proliferation via activation of the KIF15-mediated MEK-ERK signaling pathway.

The Relationship between Intrahepatic Distribution of Hepatitis B Virus Core Antigen and Serum ALT, HBV DNA Levels and HBeAg Status

Objective The clinical significance of differential distribution of hepatitis B virus(HBV)nucleocapsid antigen in hepatocytes remains unknown.The goal of this study is to determine the relationship between distinct HBV core antigen distribution pattern and alanine transaminase(ALT),liver histological inflammatory activity grades,serum HBeAg status and HBV DNA level.Methods Total of 958 cases with chronic hepatitis B were recruited into this study.Liver function tests,serum HBV DNA level,serological HBV markers and liver immunohistochemistry were examined according to the conventional instructions.Chi Square tests were performed to analyze the differences among these groups.Results It was found that 552(58%)cases were tested positive for HBV core antigen by immunohistochemical staining.Cytoplasmic hepatitis B core antigen(HBcAg)expression correlated with ALT level and serum HBV DNA and liver inflammatory activity scores,however,nuclear HBcAg expression in hepatocytes was associated with normal ALT level,lower liver inflammatory activity score and higher serum HBV DNA level and rate of HBeAg positivity.Both nuclear and cytoplasmic HBcAg expression in hepatocytes associated with a middle ALT level and liver inflammatory activity score,higher rate of serum detectable HBeAg and a higher HBV DNA level.However,undetectable core antigen was related to a lower ALT level and histological inflammatory activity grade,lower positive HBeAg rate and HBV DNA level.Conclusions Undetectable liver HBcAg is associated with HBV clearance,ALT normalization and hepatitis B e antigen(HBeAg)seroconversion,and cytoplasmic HBcAg expression associated with higher hepatic inflammatory activity.However,nuclear HBcAg expression correlates with immune tolerance characterized with normal ALT and lower liver inflammatory activity,higher HBV replication level and higher rate of HBeAg positivity.

Quasispecies of Hepatitis B Virus

Hepatitis B virus(HBV) circulates in blood and replicates in the presence of quasispecies. During HBV replication, HBV DNA polymerase lacks fidelity and proofreading function partly because its exonuclease activity is either absent or deficient. Therefore, HBV genome is mutated with unusually high frequency. And these mutations can affect more than one open reading frame due to overlapping genes. Otherwise, natural substitutions, deletions or insertions involving the Cp/ENⅡ locus in the X gene can significantly alter the extent of viral replication activity. Particular selection pressures such as host immune system and antiviral therapy readily select out escape mutants from this pre-existing quasispecies pool. Antiviral drug resistance in chronic hepatitis B(CHB) can be caused by the viral mutation frequency, the intrinsic mutability of the antiviral target site, the selective pressure exerted by the drug, the magnitude and rate of virus replication, the overall replication fitness of the mutant, the genetic barrier of the compound and the availability of replication space. Potent inhibition of HBV replication could be able to prevent the development of drug resistance because mutagenesis is replication dependent. Viral load may decline to a point where the continued production of quasispecies with the potential to resist new drug treatments no longer occurs, if viral replication can be suppressed for a sufficient length of time.