Faulty oxygen sensing disrupts angiomotin function in trophoblast cell migration and predisposes to preeclampsia

Abstract

Temporal and spatial expression of AMOT in the developing human placenta. We first characterized the spatial and temporal expression patterns of AMOT in the human placenta during early gestation. Expressed as 2 isoforms, the 80-kDa product (AMOT 80) has been implicated in endothelial cell migration, whereas the 130-kDa product (AMOT 130) is involved in changes in endothelial cell shape due to its distinguishing N-terminal extension that promotes its association with the F-actin cytoskeleton (24, 25). Protein analysis revealed that both AMOT 130 and 80 isoforms are expressed in the human placenta as early as 5 weeks of gestation, and their expression significantly increased after 10 weeks (Figure 1A), a critical time point when changes in oxygen tension and TGF-β signaling are known to occur (10, 26). Quantitative PCR analysis revealed that AMOT mRNA expression is higher in placentae from 10 to 15 weeks of gestation, compared with placentae from 5 to 9 weeks of gestation (Figure 1B). These analyses were performed on whole placenta samples, thus encompassing a heterogenous mixture of trophoblasts. Analysis of AMOT expression in distinct trophoblast subpopulations isolated through laser capture microdissection (LCM) (27) demonstrated AMOT expression in syncytiotrophoblasts (STs) and CTs and proximal (PC) and distal column (DC) trophoblasts (Figure 1C). However, with advancing gestation, AMOT expression only increased in the ST/ CT layer, where trophoblast cells are undergoing active fusion, and more importantly in the DC, where migratory and invasive EVTs reside (Figure 1C). This was corroborated by immunohistochemical analysis of AMOT in first-trimester placentae sections, which revealed (a) a striking localization of AMOT to the cell boundaries of EVTs comprising the anchoring column, particularly restricted to the intermediate and distal regions of the EVT column and absent in the proximal region; and (b) AMOT localization to the underlying, proliferative CTs, as well as in the overlying, multinucleated ST layer with advancing gestation (Figure 1D). During placenta development, critical cellular events, including trophoblast migration, rely on tightly regulated changes in oxygen tension. Hence, we examined the effect of low oxygen on AMOT expression levels. Exposure of trophoblast-derived JEG3 cells to 3% oxygen significantly decreased AMOT 130 and 80 protein levels compared with normoxic 21% oxygen (Figure 1E). TGF-β regulates AMOT expression, subcellular localization, and interaction with PAR6. During the early events of trophoblast differentiation, low oxygen tension via HIF-1α has been demonstrated to upregulate levels of TGF-β3 (10). Further, we have shown a TGF-β-dependent regulation of polarity protein PAR6 in guiding trophoblast cell migration (28). Considering that AMOT is a scaffolding protein implicated in cell polarity, we next investigated if there was a TGF-β-dependent regulation of AMOT utilizing JEG3 cells. Treatment of JEG3 cells with 10 ng/ml TGF-β1/3 ligand for 24 hours resulted in a significant

Role of A Novel Angiogenesis FKBPL-CD44 Pathway in Preeclampsia Risk Stratification and Mesenchymal Stem Cell Treatment

“…In addition to demonstrating the early biomarker potential of FKBPL and CD44, we also demonstrated the key roles for these novel proteins in trophoblast and endothelial cell function using in vitro models of SUAs remodeling important for placental development and healthy pregnancy. The importance of inappropriate response to low oxygen sensing by trophoblast cells has been previously linked with preeclampsia ( 50 ). Our results demonstrate hypoxia-mediated downregulation of FKBPL expression, as well as associated functional changes including migration, tubule formation, and clonogenic potential—all key features in placental development.…”

Low oxygen enhances trophoblast column growth by potentiating differentiation of the extravillous lineage and promoting LOX activity

“…These later observations are in line with the association of low levels of oxygen within the intervillous space and anchoring column formation and interstitial EVT infiltration into decidual mucosa in early pregnancy. However, the relationship between relative placental hypoxia and inadequate placentation in aberrant pregnancy conditions such as preeclampsia (Farrell et al, 2019) suggests that the impact of oxygen on trophoblast biology may differ according to stage of development.…”

Increased placental mitochondrial fusion in gestational diabetes mellitus: an adaptive mechanism to optimize feto-placental metabolic homeostasis?

“…IF staining was performed as previously described 16. IF intensity and colocalization were quantified using ImageJ and Volocity software version 6.3, respectively, as reported 24…”