SATB1 binds an intronic MAR sequence in human PI3kgamma in vitro.

In our previous study, an intronic MAR sequence in human PI3Kgamma gene (PIMAR) was identified using bioinformatics and biochemical methods. We used MatInspector software to identify potential binding sites for MAR-binding proteins in PIMAR. In this study, a tissue-specific MAR-binding protein (SATB1) was used to characterize the potential binding sites. Southwestern blot analysis indicates that recombinant SATB1 directly binds PIMAR sequence in vitro. Reporter gene assay showed that overexpression of SATB1 downregulates the luciferase reporter linked with reversed PIMAR by approximately threefold in the NIH-3T3 cell line. These results indicate that SATB1 may play antagonistic roles in PI3Kgamma transcriptional regulation.