Objective: To investigate the regulatory effect of phosphatidylinositol-3-kinase/protein kinase B (PI3K/AKT) signaling pathway on the subcellular distribution of negative co-stimulatory molecule B7-H4.
Methods: The HEK293 cells transfected stably with B7-H4, named B7-H4/HEK293, were treated with the PI3K/AKT specific inhibitor LY294002 and/or the nuclear export inhibitor leptomycin B (LMB). The subcellular localization of B7-H4 in B7-H4/HEK293 was observed by immunofluorescence and confocal laser scanning microscopy (CLSM), and the expression levels of B7-H4 in membrane, cytoplasm and nuclear were detected by Western blotting.
Results: CLSM showed that LY294002 effectively induced the nuclear translocation of B7-H4 when compared with vehicle group. When the B7-H4/HEK293 cells were treated with LY294002 and LMB, more B7-H4 was translocated into nuclear. Western blotting demonstrated that after the PI3K/AKT signal pathway was inhibited by LY294002 for 24 hours, the levels of B7-H4 in cell membrane and cytoplasm decreased significantly (P<0.05), while the expression in nuclear increased significantly (P<0.05).
Conclusion: The PI3K/AKT signal pathway might inhibit the nuclear translocation of B7-H4.