Figure 8.

p110γ mediates SDF-1α-induced FoxM1 expression in lung endothelial cells through inactivation of FoxO1. (A) SDF-1α-induced FoxM1 expression in human lung microvascular ECs. Lung ECs were treated with recombinant human SDF-1α (50 ng/ml) for various times and then collected for QRT-PCR analysis. n=3 experiments. *, P < 0.01 (ANOVA). (B) p110γ inhibition abrogated SDF-1α-induced FoxM1 expression in ECs. AS, AS-605240 (10 μM); TGX, TGX-221 (p110β inhibitor, 1 μM). n=3. *, P < 0.01 (t test). (C) Representative images of immunostaining demonstrating p110γ-mediated FoxO1 translocation out of nucleus induced by SDF-1α (SDF) treatment. (D) FoxO1 is a negative regulator of FoxM1 expression. Co-treatment of ECs with inhibitors for p110γ (AS) and FoxO1 (Oi) (5μM) reversed the inhibitory effect of p110γ inhibitor on SDF-1α-induced FoxM1 expression. Inhibition of nuclear export of FoxO1 by psammaphysene (SAM) (5μM) inhibited SDF-1α-induced FoxM1 expression. The inhibitor(s) was/were added to the cells 2h prior to SDF-1α addition and the cells were collected for QRT-PCR analysis of FoxM1 expression at 4h post-SDF-1α treatment. n=3. *, P < 0.01 (t test). (E) SDF-1α expression in mouse lungs following LPS challenge (7.5 mg/kg, i.p.). At times indicated, WT mouse lungs were collected for RNA isolation and QRT-PCR analysis. n=3–5 mice/time point. *, P < 0.01 (t test). (F) Our studies delineated an important role of the GPCR-activated p110γ expressed in ECs in mediating FoxM1-dependent endothelial regeneration and vascular repair and thereby promoting resolution of inflammatory injury.