Proteins associated with the messenger ribonucleoprotein particle for the estrogen-regulated apolipoprotein II mRNA

Hepatitis B virus polymerase suppresses translation of pregenomic RNA via a mechanism involving its interaction with 5' stem-loop structure

The pregenomic RNA (pgRNA) of hepadnaviruses serves a dual role: as mRNA for the core (C) and polymerase (P) synthesis and as an RNA template for viral genome replication. A question arises as to how these two roles are regulated. We hypothesized that the P protein could suppress translation of the pgRNA via its interaction with 5' stem-loop structure (epsilon or encapsidation signal). Consistent with the hypothesis, we observed up-regulation of the C protein level in the absence of the P protein expression in a physiological context. Importantly, translational suppression depended on the 5' epsilon sequence. Furthermore, the impact of the P protein on ongoing translation of the C ORF was directly demonstrated by polysome distribution analysis. We conclude that the P protein suppresses translation of the pgRNA via a mechanism involving its interaction with the 5' epsilon sequence, a finding that implicates the coordinated switch from translation to genome replication.

Intrahepatic induction of alpha/beta interferon eliminates viral RNA-containing capsids in hepatitis B virus transgenic mice

We have previously shown that hepatitis B virus (HBV) replication is abolished in the liver of HBV transgenic mice by stimuli that induce alpha/beta interferon (IFN-alpha/beta) in the liver. The present study was done to identify the step(s) in HBV replication that is affected by this cytokine in transgenic mice treated with the IFN-alpha/beta inducer polyinosinic-polycytidylic acid [poly(I-C)]. Here we show that the pool of cytoplasmic HBV pregenomic RNA (pgRNA)-containing capsids is reduced 10-fold within 9 h after poly(I-C) administration, while there is no change in the abundance of HBV mRNA or in the translational status of cytoplasmic HBV transcripts. In addition, we show that the pool of HBV DNA-containing capsids is not reduced to the same degree until at least 15 h posttreatment, and we show that virus export is not accelerated and the half-life of virions in the serum is unchanged. These results indicate that IFN-alpha/beta triggers intracellular events that either inhibit the assembly of pgRNA-containing capsids or accelerate their degradation, and that maturation and secretion of virus is responsible for clearance of HBV capsids and their cargo of replicative intermediates from the cytoplasm of the hepatocyte.

RNase H/oligonucleotide-directed mRNA purification (ROMP) of apoll mRNA

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