GLI-2 modulates retroviral gene expression.

Area of Science:

• Molecular Biology
• Virology
• Genetics

Background:

• GLI proteins are transcription factors involved in development across various species.
• Their role in regulating naturally occurring promoters, particularly in viruses, is not well understood.
• GLI-2 (also known as Tax helper protein, THP) interacts with TG-rich elements in viral enhancers.

Purpose of the Study:

• To investigate the regulatory role of GLI-2/THP on viral promoters, specifically HTLV-1 and HIV.
• To elucidate the mechanism by which GLI-2/THP modulates gene expression and viral replication.
• To identify the specific protein domains involved in GLI-2/THP's regulatory functions.

Main Methods:

• Assessed the effect of GLI-2/THP on HTLV-1, HTLV-2, and HIV-1/-2 promoter activity.
• Measured the impact of GLI-2/THP on HIV-1 replication.
• Utilized site-directed mutagenesis to examine the role of the first zinc finger in GLI-2/THP's function.

Main Results:

• GLI-2/THP suppresses gene expression from the HTLV-1 promoter but not HTLV-2.
• GLI-2/THP activates gene expression from HIV-1 and HIV-2 promoters and stimulates HIV-1 replication.
• The first zinc finger of GLI-2/THP is essential for both gene expression activation/suppression and viral replication, despite not being required for DNA binding.

Conclusions:

• GLI-2/THP exhibits dual regulatory roles (activation and suppression) on different viral promoters.
• The first zinc finger of GLI-2/THP is a critical domain mediating these diverse regulatory functions.
• These findings suggest a significant role for GLI-2 in retroviral gene regulation and provide insights into GLI protein mechanisms.