Placental HIF-1α, HIF-2α, membrane and soluble VEGF receptor-1 proteins are not increased in normotensive pregnancies complicated by late-onset intrauterine growth restriction

Abstract

Inadequate trophoblast invasion and spiral artery remodeling leading to poor placental perfusion are believed to underlie the pregnancy pathologies preeclampsia (PE) and intrauterine growth restriction (IUGR). The main objective of this study was to investigate hypoxia-inducible transcription factor-alpha (HIF-alpha) and downstream genes (VEGF receptor-1) Flt-1 and soluble fms-like tyrosine kinase 1 (sFlt-1) proteins in IUGR placentas. Placentas from normal pregnant (NP; n = 18), PE (n = 18), and IUGR (n = 10) patients were investigated. Normotensive patients with IUGR delivered babies at >or= 37 wk of gestation with birth weights of <10% and asymmetrical growth. HIF-1 alpha, -2 alpha, Flt-1, and sFlt-1 protein, and mRNA were assessed by Western and Northern blot analyses, respectively. The results are expressed as ratios of the densitometric values for each pair of pathologic and normal placentas, a ratio of 1.0 indicating no difference. Comparable to our earlier studies, the PE/NP ratios for HIF-1 alpha, -2 alpha, and Flt proteins were significantly increased by 50-100% (all P < 0.01 vs. 1.0). Unexpectedly, the IUGR/NP ratios for HIF-1 alpha and -2 alpha proteins were 1.03 +/- 0.07 and 0.96 +/- 0.16, respectively, and for Flt and sFlt were 1.14 +/- 0.15 and 0.95 +/- 0.12, respectively (all P = not significant vs. 1.0). Northern blot analysis revealed comparable levels of HIF-alpha mRNA in abnormal and normal placentas. In contrast to PE, HIF-alpha proteins and regulated genes are not increased in placentas from normotensive pregnant women delivering small, asymmetrically grown babies >or= 37 wk of gestation. The absence of an increase in HIF-alpha protein is not due to insufficient HIF-alpha mRNA for protein synthesis. Thus, the placentas from women with PE and late IUGR are fundamentally different at the molecular level.

Reduced placental prolyl hydroxylase 3 mRNA expression in pregnancies affected by fetal growth restriction

“…According to the literature, HIF-1a and -2a mRNA expression is not altered in FGR-affected pregnancies, 30 although an increase in protein levels, especially for HIF-2a, has been observed as a result of post-translational modifications. 31 In contrast, in preeclampsia, both HIF-1a and HIF-2a are overexpressed.…”

Placental development during early pregnancy in sheep: cell proliferation, global methylation, and angiogenesis in the fetal placenta

“…It has clearly been demonstrated using the knockout and other models that HIF activity is necessary for placental development, since HIF1A is involved in the regulation of placental morphogenesis, cell migration, angiogenesis, erythropoiesis, and cell metabolism, and is critical for adaptive responses to hypoxia (Cowden Dahl et al 2005, Fryer & Simon 2006. In fact, HIF1A expression is altered in preeclampsia and IUGR placentas (Rajakumar et al 2007, Zamudio et al 2007. Therefore, HIF1A may be used as a marker of compromised pregnancies.…”

Increased Myeloperoxidase in the Placenta and Circulation of Women With Preeclampsia

“…Total proteins from placental tissues were extracted by homogenizing by sonication (Ultrasonic Processor, Tekmar, microprobe setting 70 for 30 seconds) in 4 volumes of 1ϫ Laemmli buffer (50 mmol/L of Tris HCl [pH 6.8], 2% SDS, and 10% glycerol) containing 5 mmol/L of dithiothreitol, 0.5 mmol/L of PMSF, 1 mmol/L of sodium vanadate, and 1.0 L/mL of a protease inhibitor mixture. 23 Protein was determined by the BioRad protein assay. Samples were diluted into sample diluting buffer (20 mmol/L of phosphate buffer [pH 7.4] containing 2 mg/mL of BSA, 0.1% Tween 20, and 0.2% sodium azide) for the MPO ELISA, and MPO levels were as described below.…”