Oxidative stress reduces trophoblast FOXO1 and integrin β3 expression that inhibits cell motility

Preeclampsia is a serious pregnancy complication associated with placental oxidative stress and impaired trophoblast migration. The mechanism of defective trophoblast migration remains unknown. Forkhead box 01 (FOX01) is a transcription factor. Integrin beta 3 is involved in cell motility. We hypothesized that FOX01 mediates expression of trophoblast integrin beta 3, which could be impaired by oxidative stress and have implications in preeclampsia. The expressions of FOXO1 and integrin beta 3 were significantly reduced in preeclamptic placentas (n = 15) compared to that of controls (n = 15; p < 0.01). HTR-8/SVneo and JEG-3 trophoblasts were transfected to express wild-type FOX01-WT or constitutively-expressed nuclear mutant form, FOX01-AAA. The FOX01 in HTR-8/SVneo and 3A-Sub-E trophoblasts was silenced by small interfering RNA. AKT-mediated phosphorylation inactivated FOXO1, but FOXO1-AAA was not phosphorylated. The expression of trophoblast integrin beta 3 was significantly elevated by FOXO1 overexpression and inhibited by FOXO1 knockdown. FOXO1 regulates integrin beta 3 at the transcriptional level via binding to the putative FOXO1 response element site between position -1154 to -1139 (TGAGATGTTTTGAAAG) in HTR-8/SVneo trophoblasts. The level of phosphorylated FOXO1 was decreased, and the FOXO1 level was increased in trophoblasts treated with AKT inhibitor MK2206, leading to upregulation of integrin beta 3. The capabilities of trophoblast adhesion and migration were enhanced by FOXO1-overexpression or MK2206, and inhibited by silencing FOXO1 or oxidative stress with H2O2. These results suggest that FOXO1 enhances trophoblast integrin f33 expression, and mediates cell adhesion and migration. By affecting the expression of FOXO1 and cell motility in trophoblasts, oxidative stress plays a role in the development of preeclampsia.