Hypoxia inhibits Moloney murine leukemia virus expression in activated macrophages

Abstract

Hypoxia, a local decrease in oxygen tension, occurring in many pathological processes, modifies macrophage (Mphi) gene expression and function. Here, we provide the first evidence that hypoxia inhibits transgene expression driven by the Moloney murine leukemia virus-long terminal repeats (MoMLV-LTR) in IFN-gamma-activated Mphi. Hypoxia silenced the expression of several MoMLV-LTR-driven genes, including v-myc, enhanced green fluorescence protein, and env, and was effective in different mouse Mphi cell lines and on distinct MoMLV backbone-based viruses. Down-regulation of MoMLV mRNA occurred at the transcriptional level and was associated with decreased retrovirus production, as determined by titration experiments, suggesting that hypoxia may control MoMLV retroviral spread through the suppression of LTR activity. In contrast, genes driven by the CMV or the SV40 promoter were up-regulated or unchanged by hypoxia, indicating a selective inhibitory activity on the MoMLV promoter. It is interesting that hypoxia was ineffective in suppressing MoMLV-LTR-controlled gene expression in T or fibroblast cell lines, suggesting a Mphi lineage-selective action. Finally, we found that MoMLV-mediated gene expression in Mphi was also inhibited by picolinic acid, a tryptophan catabolite with hypoxia-like activity and Mphi-activating properties, suggesting a pathophysiological role of this molecule in viral resistance and its possible use as an antiviral agent.

Monocytes and dendritic cells in a hypoxic environment: Spotlights on chemotaxis and migration

“…To this aim, genetically modified macrophage cell lines and primary monocytes, macrophages and DCs expressing tumor-specific antigens or immunoregulatory cytokines were employed for adoptive immunotherapy of cancer (Nishihara et al, 1995;Lei et al, 2000;Kaplan et al, 1999;Melero et al, 1999;Ringenbach et al, 1998). More recently, macrophage vectors were engineered to express hypoxia-activated therapeutic genes and to produce recombinant viruses carrying the therapeutic gene (Griffiths et al, 2000;Carta et al, 2001;Burke et al, 2002a;Puppo et al, 2007;Pastorino et al, 2001) . This approach combines two levels of gene targeting: the ability of cells to ''home'' to and accumulate in hypoxic areas with the hypoxic activation of therapeutic genes.…”

Role of Cellular Iron and Oxygen in the Regulation of HIV-1 Infection

“…Hypoxia (1% O 2 ) induces lytic replication of EBV [92] and Kaposi sarcoma-associated herpesvirus [93], but suppresses replication of oncolytic parvovirus Minute virus of mice [94], adenovirus [95] or Moloney murine leukemia virus [96]. Primary T cells cultured at 3–6% O 2 maintain an intracellular redox environment similar to the in vivo situation, as opposed to T cells cultured at atmospheric 21% O 2 , in which the intracellular redox state is significantly altered [97].…”

Hypoxia transcriptionally induces macrophage-inflammatory protein-3α/CCL-20 in primary human mononuclear phagocytes through nuclear factor (NF)-κB

“…Fresh medium was added 24 h after infection, and stable transfectants were selected by treatment with 2 g/ml puromycin (Sigma, Milano, Italy) for an additional 5 days. Infectivity was determined by FACS analysis of cells transduced with the LV-shC lentivector expressing control shRNA and EGFP, as detailed [43].…”