Related Experiment Video
Updated: Apr 17, 2026
09:35
Development of a Hepatitis B Virus Reporter System to Monitor the Early Stages of the Replication Cycle
Published on: February 1, 2017
14.1K
nc886 noncoding RNA regulates hepatitis B virus replication via PKR-dependent eIF2α phosphorylation.
Zahra Zahid Piracha1, Umar Saeed2,3
1Szechenyi Istvan University, Egyetem Square 1, Gyor, Hungary.
Frontiers in Cellular and Infection Microbiology
|April 16, 2026
Summary
The small noncoding RNA nc886 inhibits protein kinase R (PKR) and suppresses Hepatitis B virus (HBV) replication. Depleting nc886 activates PKR, blocking HBV gene expression and offering a potential therapeutic target for HBV.
Area of Science:
- Hepatology
- Molecular Biology
- Virology
Background:
- Hepatitis B virus (HBV) replication is influenced by host stress and innate immunity.
- The small noncoding RNA nc886 is an endogenous inhibitor of protein kinase R (PKR).
- The precise role of nc886 in HBV biology and its regulatory axis with PKR are not fully understood.
Purpose of the Study:
- To elucidate the function of the nc886-PKR-eIF2α pathway in HBV-replicating hepatoma cells.
- To determine if nc886 depletion inhibits HBV replication through PKR-dependent translational control.
Main Methods:
- Utilized Huh7 cells and HBV-replicating Huh7 cells.
- Performed loss-of-function studies using siRNAs against nc886 and PKR.
- Assessed HBV replication markers (DNA, RNA, antigens) and PKR-eIF2α-ATF4 signaling.
- Modulated PKR and integrated stress response (ISR) pathways pharmacologically.
Main Results:
- nc886 silencing enhanced PKR-dependent eIF2α phosphorylation and ATF4 activation.
- Depletion of nc886 reduced HBV RNA and DNA levels, as well as secreted viral antigens.
- PKR knockdown rescued nc886-mediated inhibition of HBV replication and ISR activation.
- Pharmacological modulation of ISR restored HBV replication in nc886-silenced cells.
Conclusions:
- nc886 negatively regulates PKR-dependent ISR signaling during HBV replication.
- nc886 depletion activates PKR and eIF2α, leading to a translational block of HBV gene expression.
- The nc886-PKR-eIF2α axis is a novel host regulatory mechanism relevant for developing host-directed HBV therapies.
Related Concept Videos
01:25Hepatitis
63
Hepatitis is an inflammatory condition of the liver most commonly caused by hepatotropic viruses (A–E), though non-infectious causes such as alcohol and drugs also exist.Hepatitis AHepatitis A virus (HAV) is a non-enveloped RNA virus of the Picornaviridae family. It is primarily transmitted via the fecal-oral route, typically through ingestion of contaminated food or water. After ingestion, HAV enters the bloodstream through the oropharynx or intestinal epithelium and reaches the liver.
63
01:30Inhibitors of Viral Protein Synthesis
37
Protein synthesis is indispensable for viral replication, as viruses lack the cellular machinery required for this process and must hijack the host's translational apparatus. In response, host cells deploy a critical innate immune defense involving interferons, specialized cytokines that play a central role in inhibiting viral propagation.Upon viral detection, infected cells release interferons that bind to receptors on adjacent uninfected cells, activating the JAK-STAT signaling pathway and...
37
01:29Viruses with RNA Genomes
1.4K
RNA viruses are categorized into positive-strand, negative-strand, or double-stranded groups based on their genomic structure and replication mechanisms. This classification dictates how they exploit host cellular machinery for protein synthesis and replication. Some RNA viruses also utilize reverse transcription as part of their life cycle, further diversifying their replication strategies.Positive-Strand RNA VirusesPositive-strand RNA viruses have genomes that function directly as messenger...
1.4K
02:28Leaky Scanning
5.9K
During most eukaryotic translation processes, the small 40S ribosome subunit scans an mRNA from its 5' end until it encounters the first start AUG codon. The large 60S ribosomal subunit then joins the smaller one to initiate protein synthesis. The location of the translation initiation is largely determined by the nucleotides near the start codon as there may be multiple translation initiation sites present on the mRNA. Marilyn Kozak discovered that the sequence RCCAUGG (where R...
5.9K
00:58Eukaryotic RNA Polymerases
28.5K
RNA Polymerase (RNAP) is conserved in all animals, with bacterial, archaeal, and eukaryotic RNAPs sharing significant sequence, structural, and functional similarities. Among the three eukaryotic RNAPs, RNA Polymerase II is most similar to bacterial RNAP in terms of both structural organization and folding topologies of the enzyme subunits. However, these similarities are not reflected in their mechanism of action.
All three eukaryotic RNAPs require specific transcription factors, of which the...
All three eukaryotic RNAPs require specific transcription factors, of which the...
28.5K
01:47Transcription Initiation
22.3K
Initiation is the first step of transcription in eukaryotes. Prokaryotic RNA Polymerase (RNAP) can bind to the template DNA and start transcribing. On the other hand, transcription in eukaryotes requires additional proteins, called transcription factors, to first bind to the promoter region in the DNA template. This binding helps recruit the specific RNAP that can assemble on the DNA and start transcription.
The promoters and enhancers and their accessory proteins allow tight regulation of...
The promoters and enhancers and their accessory proteins allow tight regulation of...
22.3K