Function-Specific Intracellular Signaling Pathways Downstream of Heparin-Binding EGF-Like Growth Factor Utilized by Human Trophoblasts1

Abstract

Heparin-binding EGF-like growth factor (HBEGF) is expressed by trophoblast cells throughout gestation. First-trimester cytotrophoblast cells are protected from hypoxia-induced apoptosis because of the accumulation of HBEGF through a posttranscriptional autocrine mechanism. Exogenous application of HBEGF is cytoprotective in a hypoxia/reoxygenation (H/R) injury model and initiates trophoblast extravillous differentiation to an invasive phenotype. The downstream signaling pathways induced by HBEGF that mediate these various cellular activities were identified using two human first-trimester cytotrophoblast cell lines, HTR-8/SVneo and SW.71, with similar results. Recombinant HBEGF (1 nM) induced transient phosphorylation of MAPK3/1 (ERK), MAPK14 (p38), and AKT within 15 min and JNK after 1-2 h. To determine which downstream pathways regulate the various functions of HBEGF, cells were treated with specific inhibitors of the ERK upstream regulator MEK (U0126), the AKT upstream regulator phosphoinositide-3 (PI3)-kinase (LY294002), MAPK14 (SB203580), and JNK (SP600125), as well as with inactive structural analogues. Only SB203580 specifically prevented HBEGF-mediated rescue during H/R, while each inhibitor attenuated HBEGF-stimulated cell migration. Accumulation of HBEGF at reduced oxygen was blocked only by a combination of U0126, SB203580, and SP600125. We conclude that HBEGF advances trophoblast extravillous differentiation through coordinate activation of PI3 kinase, ERK, MAPK14, and JNK, while only MAPK14 is required for its antiapoptotic activity. Additionally, hypoxia induces an autocrine increase in HBEGF protein levels through MAPK14, JNK or ERK. These experiments reveal a complexity of the intracellular signaling circuitry that regulates trophoblast functions critical for implantation and placentation.

Progesterone-induced blocking factor differentially regulates trophoblast and tumor invasion by altering matrix metalloproteinase activity

“…The membraneanchored pro-HB-EGF is cleaved by metalloproteinases in order to release the soluble form of HB-EGF [54]. HB-EGF provokes differentiation of trophoblast cells to an invasive phenotype through coordinate activation of PI-3K/Akt, ERK, MAPK14, and JNK pathways [55]. By downregulating HB-EGF in the trophoblast, PIBF might control physiologic trophoblast invasion.…”

Stress responses at the endometrial–placental interface regulate labyrinthine placental differentiation from trophoblast stem cells

“…Thus, MAPK8/9 mediates stem cell survival and differentiation responses. MAPK8/9 is activated in mouse and human placental cells in vivo and in vitro and plays a role in adhesion, invasion, survival, and apoptosis (Zhong et al 2004, Cindrova-Davies et al 2007, Kang et al 2007, Lucchi & Moore 2007, Yang et al 2008b, Abell et al 2009, Jessmon et al 2010, Zhu et al 2010. Unlike AMPK, SAPK has no role in mediating loss of potency factors in cultured mouse TSC (Abell et al 2009) or ESC (Xu & Davis 2010).…”

HER1 Signaling Mediates Extravillous Trophoblast Differentiation in Humans1

“…However, as only inhibition of the PIK3 pathway had any effect of HBEGFmediated JAR cell, migration we conclude that HBEGFmediated JAR cell migration is mediated by HER1 tyr1068 phosphorylation and sustained downstream activation of the PIK3 and AKT1 signaling pathways. Recently it has also been shown that in HTR8 SVneo and SW.71 trophoblast cell lines, HBEGF-mediated cell migration is mediated by PIK3, MAPK14, ERK, and JNK pathways but with no apparent cross talk between pathways [42]. However, no direct assessment of either MAP2K1 or PIK3 activation was made in this study, and the earliest time point studied was 15 min [42].…”