[Show abstract][Hide abstract] ABSTRACT: APOBEC3G (A3G), a member of the recently discovered family of human cytidine deaminases, is expressed in peripheral blood
lymphocytes and has been shown to be active against HIV-1 and other retroviruses. To gain new insights into the transcriptional
regulation of this restriction factor, we cloned and characterized the promoter region of A3G. Transcriptional start sites
were identified by 5′-rapid amplification of cDNA ends analysis. Luciferase reporter assays demonstrated that a 1025 bp A3G
promoter sequence (from −959 to +66 relative to the major transcriptional start site) displayed constitutive promoter activity.
In T cells, the A3G promoter was not inducible by mitogenic stimulation, interferon treatment or expression of HIV-1 proteins.
Using a series of 5′ deletion promoter constructs in luciferase reporter assays, we identified a 180 bp region that was sufficient
for full promoter activity. Transcriptional activity of this A3G core promoter was dependent on a GC-box (located at position
−87/−78 relative to the major transcriptional start site) and was abolished after mutation of this DNA element. Electrophoretic
mobility shift assays and chromatin immunoprecipitation assays demonstrated that the identified GC-box represented a binding
site for the ubiquitous transcription factors specificity protein (Sp) 1 and Sp3.
Full-text · Article · Feb 2007 · Nucleic Acids Research