Gadd45α as an upstream signaling molecule of p38 MAPK triggers oxidative stress-induced sFlt-1 and sEng upregulation in preeclampsia

Abstract

Preeclampsia (PE) is known to be associated with increased circulating levels of anti-angiogenic factors, such as soluble fms-related tyrosine kinase-1 (sFlt-1) and soluble endoglin (sEng). However, the way that placental oxidative stress results in the elevation of these two factors remains enigmatic. We have observed the overexpression of growth arrest and DNA damage-inducible 45 alpha (Gadd45α) and excessive activation of p38 mitogen-activated protein kinase (MAPK) in preeclamptic placentas compared with normotensive controls, together with increased levels of sFlt-1 and sEng in maternal sera in patients with PE. Moreover, Gadd45α knockdown or p38 inhibition provides protective effects in hypoxia/reoxygenation (H/R)-exposed human umbilical vein endothelial cells (HUVECs) by suppressing oxidative stress, inhibiting apoptosis, and promoting their potential for in vitro angiogenesis. A regulatory signaling pathway in which H/R intervention causes the induction of Gadd45α leading to p38 activation and ultimately an increase in sFlt-1 and sEng secretion in HUVECs has concurrently been established. Our study opens up a promising new avenue of investigation for increasing the understanding of the origin of sFlt-1 and sEng in PE and provides novel therapeutic targets for pregnancy complications arising from placental endothelial dysfunction.

Imbalance between proliferation and apoptosis−related impaired GPR30 expression is involved in preeclampsia

“…The in vitro tube formation assay was as previously described [21,26]. Briefly, Matrigel (BD Biosciences) was thawed at 4°C overnight and then diluted with serum-free medium at a ratio of 1:2; the mixture was distributed into a 96-well plate (65 μl/well) and incubated at 37°C for 2 hrs.…”

“…The hypoxia/reoxygenation (H/R) treatment was performed as previously described [21][22][23][24]. In brief, to decrease the influence of stimulation by serum mitogens, HUVECs were pre-incubated for 12 hrs in low-serum medium which was supplemented with 1% FBS before H/R treatment.…”

“…The HUVEC migration assay was performed as reported previously [21,26]. In brief, 24-well plates were used as the outer chambers and polycarbonate filters (8-μm pores; Transwell chamber; Millipore) were used as the inner chambers.…”

“…Sample collection was carried out as described previously [21]. Placental (maternal side), decidua and umbilical cord tissues were harvested within 1 hr of delivery.…”

“…After treatment, protein samples of HUVECs were analysed using Western blotting techniques, as previously established in our laboratory [21,25]. The primary antibodies used were as follows: …”