WNK1 mediates amphiregulin-induced MMP9 expression and cell invasion in human extravillous trophoblast cells

The invasion of human extravillous trophoblast (EVT) cells is a critical event required for a successful pregnancy. Amphiregulin, a ligand of the epidermal growth factor receptor (EGFR), has been shown to stimulate cell invasion in an immortalized human EVT cell line, HTR-8/SVneo. The with-no-lysine kinase 1 (WNK1) is involved in regulating cell invasion. It is known that WNK1 is expressed in the human placenta, but its role in human EVT cells remains unknown. In the present study, we show that AREG treatment phosphorylated WNK1 at Thr60 in both HTR-8/SVneo and primary human EVT cells. The stimulatory effect of AREG on WNK1 phosphorylation was mediated by the activation of PI3K/AKT, but not the ERK1/2 signaling pathway. AREG upregulated matrix metalloproteinase 9 (MMP9) but not MMP2. In addition, cell invasiveness was increased in response to the treatment of AREG. Using the siRNA-mediated knockdown approach, our results showed that the knockdown of WNK1 attenuated the AREG-induced upregulation of MMP9 expression and cell invasion. Moreover, the expression of WNK1 was downregulated in the placentas with preeclampsia, a disease resulting from insufficiency of EVT cell invasion during pregnancy. This study discovers the physiological function of WNK1 in human EVT cells and provides important insights into the regulation of MMP9 and cell invasion in human EVT cells.