Human GM-CSF induces HIV-1 LTR by multiple signalling pathways

Area of Science:

• Virology
• Immunology
• Molecular Biology

Background:

• Human immunodeficiency virus type-1 (HIV-1) gene expression is influenced by various cytokines and growth factors.
• The specific impact of granulocyte-macrophage colony-stimulating factor (GM-CSF) on HIV-1 long terminal repeat (LTR)-mediated transcription remains uncharacterized.

Purpose of the Study:

• To investigate the effect of GM-CSF on HIV-1 LTR-mediated transcription.
• To identify the regulatory elements and signaling pathways involved in GM-CSF-induced HIV-1 LTR activation.

Main Methods:

• Transient transfection assays using HIV-1 LTR reporter constructs in cells expressing human GM-CSF receptors.
• Mutational analysis of HIV-1 LTR reporter constructs and GM-CSF receptor (GM-CSFR) cytoplasmic domains.
• Pharmacological inhibition and activation of specific signaling pathways (PI3-K, MAPK).

Main Results:

• GM-CSF strongly activated HIV-1 LTR-mediated transcription.
• NF-kappaB and Sp1 binding sites within the HIV-1 LTR were identified as crucial positive regulatory elements.
• Specific regions and tyrosine residues in the GM-CSFR beta subunit were essential for LTR activation.
• The PI3-K pathway partially contributed, while the MAPK pathway was not essential, suggesting involvement of other signaling pathways.

Conclusions:

• GM-CSF upregulates HIV-1 LTR-driven transcription.
• Activation involves modulation of NF-kappaB and Sp1 transcription factors.
• Multiple signaling pathways, including but not limited to PI3-K, mediate GM-CSF's effect on HIV-1 transcription.