Intracellular localization of human ZBP1: Differential regulation by the Z-DNA binding domain, Zα, in splice variants

Department of Chemistry, Sungkyunkwan University, Sŏul, Seoul, South Korea
Biochemical and Biophysical Research Communications (Impact Factor: 2.28). 10/2006; 348(1):145-52. DOI: 10.1016/j.bbrc.2006.07.061
Source: PubMed

ABSTRACT We investigated the subcellular distribution of human ZBP1, which harbors the N-terminal Z-DNA binding domains, Zalpha and Zbeta. ZBP1 was distributed primarily in the cytoplasm and occasionally as nuclear foci in interferon (IFN)-treated primary hepatocellular carcinoma cells, and in several other transfected cell types. In leptomycin B (LMB)-treated cells, endogenous ZBP1 efficiently accumulated in nuclear foci, which overlapped PML oncogenic domains (PODs) or nuclear bodies (NBs). In transfection assays, the unique C-terminal region of ZBP1 was necessary for its typical cytoplasmic localization. Interestingly, the Zalpha-deleted form displayed an increased association with PODs compared to wild-type and, unlike wild-type, perfectly accumulated in PODs in LMB-treated cells, implying that the presence of Zalpha domain also facilitates the cytoplasmic localization. Our results demonstrate that ZBP1 is localized primarily in the cytoplasm but also associated with nuclear PODs in IFN or LMB-treated cells. Given that about half of ZBP1 mRNA lacks exon 2 encoding the Zalpha domain, our data also suggest that the localization of ZBP1 may be differentially regulated by the Z-DNA binding domain, Zalpha, in splice variants.


Available from: Thanh Pham, Jun 03, 2015
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: DNA-dependent activator of interferon regulatory factor (DAI) acts as a cytosolic B-form DNA sensor that induces type I interferons. However, DAI is not required for DNA sensing in certain cell types due to redundancy of the DNA sensing system. Here, we investigated the effect of DAI on herpes simplex virus type-1 (HSV-1) infection in HepG2 hepatocellular carcinoma cells. DAI transcription was induced after interferon-γ treatment or HSV-1 infection. HSV-1 replication was enhanced by DAI-knockdown, and ectopic DAI expression repressed viral replication in a manner requiring the Zβ and D3 domains, but not the Zα domain. This activity of DAI was more prominent at low multiplicity of infection (MOI) and correlated with the reduced expression of viral immediate-early genes. Consistently, DAI repressed the activation of ICP0 promoter in reporter gene assays. DAI-knockdown did not affect the B-DNA-mediated interferon-β transcription and IRF3 activation, and overexpression of DAI and RIP1 did not enhance NF-κB activation by B-DNA treatment, demonstrating that DAI is not essential for the B-DNA-mediated interferon production in HepG2 cells. DAI colocalized with ICP0 in a subset of nuclear and cytoplasmic foci in infected cells and interacted with ICP0 in co-immunoprecipitation assays. The anti-HSV-1 effect of DAI was not observed in ICP0-deleted mutant virus infection at high MOI in HepG2 cells and mouse embryonic fibroblasts. Degradation of IFI16 and PML by ICP0 was enhanced in infection of DAI-knockdown cells. Collectively, these results demonstrate that DAI can suppress HSV-1 growth independent of DNA sensing through mechanisms involving suppression of viral genomes and regulation of ICP0.
    Journal of Virology 01/2013; 87(6). DOI:10.1128/JVI.02860-12 · 4.65 Impact Factor
  • Source
    Journal of Biomolecular NMR 08/2014; 60(2-3). DOI:10.1007/s10858-014-9858-7 · 3.31 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Vaccination reduces morbidity and mortality from pneumonia but its effect on the tissue-level response to infection is still poorly understood. We evaluated pneumonia disease progression, acute phase response and lung gene expression profiles in mice inoculated intranasally with virulent gram-positive Streptococcus pneumoniae serotype (ST) 3, with and without prior immunization with pneumococcal polysaccharide ST 3 (PPS3), or co-immunization with PPS3 and with a low dose of lipopolysaccharide (LPS). Pneumonia severity was assessed in the acute phase, 5, 12, 24 and 48 h post-inoculation (p.i.) and the resolution phase of 7 days p.i. Primary PPS3 specific antibody production was upregulated and IgM binding to pneumococci increased in PPS3-immunized mice. Immunizations with PPS3 or PPS3 + LPS decreased bacterial recovery the lung and blood at 24 and 48 h and increased survival. Microarray analysis of whole lung RNA revealed significant changes in the acute phase protein serum amyloid A (SAA) between noninfected and infected mice, which were attenuated by immunization. SAA transcripts were higher in the liver and lungs of infected controls, and SAA protein was elevated in serum, but decreased in PPS3-immunized mice. Thus, during a virulent pneumonia infection, prior immunization with PPS3 in an IgM-dependent manner as well as co-immunization with PPS3 + LPS attenuated pneumonia severity and promoted resolution of infection, concomitant with significant regulation of cytokine gene expression in the lungs, and acute phase proteins in the lungs, liver and serum.
    Clinical and vaccine Immunology: CVI 02/2013; DOI:10.1128/CVI.00593-12 · 2.37 Impact Factor