Figure 4.

Increased cAMP-induced expression from HIV-1 and CXCR4 promoters is facilitated by PKA. (A) In comparison with untreated samples, forskolin-stimulated cells exhibit up to a ~6-fold upregulation in luciferase expression. This upregulation is completely inhibited by H-89 pretreatment for one hour. H-89 alone slightly diminishes basal luciferase expression. All firefly luciferase readings were normalized to Renilla readings by cotransfecting cells with the pRL-TK Renilla luciferase construct and expressed as fold over untreated samples. (B) qRT-PCR assays revealed that in comparison with untreated samples, forskolin-treated samples showed a ~4.6-fold increase in CXCR4 transcript levels. This was reduced by 50% when samples are pretreated with H-89. Results were normalized to RPLPO expression and expressed in linear scale as fold over untreated samples. Asterisks indicate significance of P < 0.05 using Student’s t–test.