Abstract
BackgroundNuclear factor kappa B (NF-κB) is a key transcription factor that plays a crucial role in host survival during infection by pathogens. Therefore, it has been a priority of many pathogens to manipulate the cellular NF-κB activity in order to create a favorable environment for their survival inside the host.ResultsWe observed that heterologous expression of the open reading frame 2 (ORF2) protein in human hepatoma cells led to stabilization of the cellular I kappa B alpha (IκBα) pool, with a concomitant reduction in the nuclear localization of the p65 subunit of NF-κB and inhibition of NF-κB activity. Although basal or TPA induced phosphorylation of IκBα was not altered, its ubiquitination was markedly reduced in ORF2 expressing cells. Further analysis revealed that ORF2 protein could directly associate with the F-box protein, beta transducin repeat containing protein (βTRCP) and ORF2 over expression resulted in reduced association of IκBα with the SKP1 and CUL1 components of the SCFβTRCP complex. Chromatin immunoprecipitation (ChIP) assay of the proximal promoter regions of MHC-I heavy chain and IL-8 genes using p65 antibody and LPS stimulated ORF2 expressing cell extract revealed decreased association of p65 with the above regions, indicating that ORF2 inhibited p65 binding at endogenous promoters.ConclusionsIn this report we suggest a mechanism by which ORF2 protein of HEV may inhibit host cell NF-κB activity during the course of a viral infection.
Highlights
Nuclear factor kappa B (NF-κB) is a key transcription factor that plays a crucial role in host survival during infection by pathogens
Heterologous expression of the open reading frame 2 (ORF2) protein inhibits NF-κB activity In order to test whether ORF2 or ORF3 protein of Hepatitis E virus (HEV) inhibit cellular NF-κB activity, a reporter vector with IL-2 receptor promoter region, which contains NF-κB element, cloned upstream of the chloramphenicol acetyl transferase coding sequence
Assay of chloramphenicol acetyl transferase (CAT) activity using these cell extracts revealed that ORF2 protein inhibited the NF-κB Chloramphenicol acetyl transferase (CAT) activity (Figure 1A)
Summary
Nuclear factor kappa B (NF-κB) is a key transcription factor that plays a crucial role in host survival during infection by pathogens. It has been a priority of many pathogens to manipulate the cellular NF-κB activity in order to create a favorable environment for their survival inside the host. As part of the host defense mechanism against invading pathogens, NF-κB activation is required for resistance to a variety of viral, bacterial, and parasitic infections [1] Many viruses such as HIV, exploit this property to their benefit by driving their gene expression through κB response elements located in their promoters [2]. Inhibition of NF-κB activity by these pathogens has been shown to be important for pathogenesis
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
