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Induction of activator protein 1 (AP-1) in macrophages by human immunodeficiency virus type-1 NEF is a cell-type-specific response that requires both hck and MAPK signaling events

Lookup NU author(s): Professor Derek Mann


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Human immunodeficiency virus type 1 (HIV-1) Nef is important for viral infectivity and pathogenicity. HIV-1 infection is associated with inappropriate activation and defects in the function of monocytes/macrophages. We have studied the effects of HIV-1 Nef in the murine (RAW264.7) and human (THP-1) monocyte-macrophage cell lines. Investigation of the activator protein-1 (AP-1) transcription factor showed that Nef expression induced both its DNA binding and transcriptional activities. Increased AP-1 DNA binding activity in RAW264.7 cells was associated with raised levels of c-Fos expression and induction of mRNA for the AP-1 responsive tissue inhibitor of metalloproteinases-1 (TIMP-1) gene. Mutagenesis and kinase inhibition studies were employed to determine signaling pathways used by Nef to induce AP-1. Data from these studies indicated that induction of AP-1 by Nef is likely to be mediated through the MAPK (ERK1 and 2) signaling pathway and requires the proline-rich PxxP motif of Nef, suggesting the involvement of upstream protein kinases belonging to the Src family. Effects of Nef on AP-1 induction were cell lineage-specific, being stimulatory in macrophages, inhibitory in T cells and without effect in HeLa cells. These latter two observations led us to test the possibility that cell-specific interactions of Nef with Src family proteins may modulate AP-1 activity. To this end we demonstrated that a dominant-negative Hck mutant caused inhibition of Nef-mediated AP-1 DNA binding activity in RAW cells. In conclusion, induction of AP-1 by Nef is a specific feature of human and murine macrophage cell lines that requires signal transduction events involving Hck and MAPKs.

Publication metadata

Author(s): Mann DA; Biggs TE; Cooke SJ; Barton CH; Harris MP; Saksela K

Publication type: Article

Publication status: Published

Journal: Journal of Molecular Biology

Year: 1999

Volume: 290

Issue: 1

Pages: 21-35

Print publication date: 02/07/1999

ISSN (print): 0022-2836

Publisher: Academic Press


DOI: 10.1006/jmbi.1999.2849


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