Article

Ikappakappa mediates NF-kappaB activation in human immunodeficiency virus-infected cells.

Department of Immunology, Mayo Clinic, Rochester, Minnesota 55905, USA.
Journal of Virology (Impact Factor: 4.65). 06/1999; 73(5):3893-903.
Source: PubMed

ABSTRACT Human monocytes and macrophages are persistent reservoirs of human immunodeficiency virus (HIV) type-1. Persistent HIV infection of these cells results in increased levels of NF-kappaB in the nucleus secondary to increased IkappaBalpha, IkappaBbeta, and IkappaBepsilon degradation, a mechanism postulated to regulate viral persistence. To characterize the molecular mechanisms regulating HIV-mediated degradation of IkappaB, we have sought to identify the regulatory domains of IkappaBalpha targeted by HIV infection. Using monocytic cells stably expressing different transdominant molecules of IkappaBalpha, we determined that persistent HIV infection of these cells targets the NH2 but not the COOH terminus of IkappaBalpha. Further analysis demonstrated that phosphorylation at S32 and S36 is necessary for HIV-dependent IkappaBalpha degradation and NF-kappaB activation. Of the putative N-terminal IkappaBalpha kinases, we demonstrated that the Ikappakappa complex, but not p90(rsk), is activated by HIV infection and mediates HIV-dependent NF-kappaB activation. Analysis of viral replication in cells that constitutively express IkappaBalpha negative transdominant molecules demonstrated a lack of correlation between virus-induced NF-kappaB (p65/p50) nuclear translocation and degree of viral persistence in human monocytes.

0 Followers
 · 
70 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: Drug resistance remains a great challenge in HIV/AIDS treatment despite the recent advances in novel therapeutics. It may be a good strategy to develop drugs targeting the essential host factors to decrease the risk of drug resistance. Previous studies suggested that so many host kinases play roles in HIV life cycles. More importantly, many kinase genes are drugable targets, therefore, it is vital to figure out host kinases responsible for HIV-1 infection and replication to provide novel therapeutic regimens and to deepen our understanding to HIV-host interaction. In present work, a high throughput RNAi screen with a shRNA library against 474 kinases was applied to HEK293T cells stably expressed a HIV-1 LTR (long terminal repeat)-driven reporter plasmid. Four genes, AK1, EphB2, PRKACB and CDK5R2, were found to specifically suppress the HIV-1 LTR activity following effective knockdown. Furthermore, overexpression of AK1 and PRKACB upregulated the HIV-1 LTR activity. Therefore, AK1 and PRKACB are in positive control of HIV-1 activity. DNA microarray analysis demonstrated that overlapped genes between AK1-silenced and PRKACB-silenced cells were mainly enriched in several amino acid biosynthesis pathways, TGF-β signaling and p53 signaling pathways. These alterations may repress the viral infection by the downregulation of ERK1/2, p38MAPK and NFκB signaling pathways. Collectively, our work uncovers several host kinases involving the HIV-1 infection and may provide potential therapeutic targets for AIDS treatment in future.
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Mononuclear phagocytes including monocytes and macrophages, are important defense components of innate immunity, but can be detrimental in HIV-1 infection by serving as the principal reservoirs of virus in brain and triggering a strong immune response. These viral reservoirs represent a challenge to HIV-1 eradication since they continue producing virus in tissue despite antiretroviral therapy. HIV-1 associated neurocognitive disorders (HAND) involve alterations to the blood-brain barrier and migration of activated HIV-1 infected monocytes to the brain with subsequent induced immune activation response. Our group recently showed that HIV replication in monocyte-derived macrophages (MDM) is associated with increased cystatin B. This cysteine protease inhibitor also inhibits the interferon-induced antiviral response by decreasing levels of tyrosine phosphorylated STAT-1. These recent discoveries reveal novel mechanisms of HIV persistence that could be targeted by new therapeutic approaches to eliminate HIV in macrophage reservoirs. However, cystatin B has been also associated with neuroprotection. Cystatin B is an inhibitor of the cysteine protease cathepsin B, a potent neurotoxin. During HIV-1 infection cystatin B and cathepsin B are upregulated in macrophages, meanwhile there is a reduction in cystatin/cathepsin interactions, leading to increased cathepsin B secretion and activity that induce neuronal apoptosis. Increased intracellular expression of both proteins was recently found in monocytes from Hispanic women with HAND. These findings provide new evidence for the role of cathepsin /cystatin system in the neuropathogenesis induced by HIV-infected macrophages. We summarize recent research on cystatin B and one of its substrates, cathepsin B, in HIV replication in macrophages and neuropathogenesis.
    Current HIV Research 05/2014; DOI:10.2174/1570162X12666140526120249 · 2.14 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Moloney murine leukemia virus (MoMuLV)-ts1-mediated neuronal degeneration in mice is likely due to loss of glial support and release of inflammatory cytokines and neurotoxins from surrounding ts1-infected glial cells including astrocytes. NF-κB is a transcription factor that participates in the transcriptional activation of a variety of immune and inflammatory genes. We investigated whether ts1 activates NF-κB in astrocytes and examined the mechanism(s) responsible for the activation of NF-κB by ts1 infection in vitro. Here we present evidence that ts1 infection of astrocytes in vitro activates NF-κB by enhanced proteolysis of the NF-κB inhibitors, IκBα and IκBβ. In in vitro studies using protease inhibitors, IκBα proteolysis in ts1-infected astrocytes was significantly blocked by a specific calpain inhibitor calpeptin but not by MG-132, a specific proteasome inhibitor, whereas rapid IκBβ proteolysis was blocked by MG-132. Furthermore, treatment with MG-132 increased levels of multi-ubiquitinated IκBβ protein in ts1-infected astrocytes. These results indicate that the calpain proteolysis is a major mechanism of IκBα proteolysis in ts1-infected astrocytes. Additionally, ts1 infection of astrocytes in vitro increased expression of inducible nitric oxide synthase (iNOS), a NF-κB-dependent gene product. Our results suggest that NF-κB activation in ts1-infected astrocytes is mediated by enhanced proteolysis of IκBα and IκBβ through two different proteolytic pathways, the calpain and ubiquitin-proteasome pathways, resulting in increased expression of iNOS, a NF-κB-dependent gene.
    Journal of NeuroVirology 01/2001; 7(5):466-475. DOI:10.1080/135502801753170327 · 3.32 Impact Factor

Full-text (2 Sources)

Download
13 Downloads
Available from
May 19, 2014