Abstract
The serine protease inhibitor alpha1-antitrypsin (A1AT) may possess protective functions of impaired organs in a manner independent of its protease inhibitor activity. A1AT expression has been shown to fluctuate in patients with pregnancy-induced hypertension, which suggests that A1AT may play a role in the syncytialization of villous trophoblasts. A1AT expression was knocked down in primary trophoblasts. RNA was extracted from these cells and subjected to RNA-sequencing analysis to determine the levels of expression of markers of syncytialization and inflammation. In addition, A1AT protein was localized in trophoblastic cells in placental tissues. Knockdown of A1AT upregulated the expression of FOSL1 and markers of syncytialization, as well as cell fusion, whereas overexpression of A1AT had the opposite effects. FOSL1 overexpression stimulated syncytialization, similar to the effects of A1AT knock down. Inhibitors of p38MAPK and JNK reduce the expression of inflammatory factors, whereas a p38MAPK inhibitor suppressed FOSL1 expression. Collectively, these findings indicated A1AT may negatively regulate inflammatory responses by controlling the activation of p38MAPK and JNK, and that p38MAPK mediates trophoblast syncytialization by altering FOSL1 expression. Therefore, a dysfunction in A1AT could be responsible for abnormal placental formation and pregnancy-associated disorders.
Highlights
Immunostaining of placental tissues with antibody to Alpha-1 antitrypsin (A1AT) showed that A1AT was localized to cytotrophoblasts and syncytiotrophoblasts (Figure 1a), and western blotting showed that isolated trophoblasts express several molecular weights of A1AT, presumably glycosylated and cleaved forms (Figure 1b)
A total of 1334 differentially expressed genes (DEGs) were detected (Figure 1c), with gene ontology (GO) biological process analysis showing that many of the upregulated DEGs were associated with the inflammatory response (Figure 1d)
To determine whether JNK and p38MAPK mediated the A1AT-induced expression of inflammatory cytokines, BeWo cells with knocked down A1AT were treated with inhibitors of JNK (SP600125) and p38MAPK (SB203580)
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. During the process of syncytialization, cytotrophoblasts fuse to form multinucleate syncytiotrophoblasts, which are characterized by morphological and functional differentiation In both primary human trophoblasts and the trophoblast-derived choriocarcinoma cell line BeWo, intracellular cyclic AMP (cAMP) mediates the production of human chorionic gonadotropin (hCG) and progesterone [12,13], and upregulates fusogenic syncytins through the transcription factors, glial cell missing 1 (GCM1), and ovo like transcriptional repressor 1 (OVOL1) [14–16]. Pathological conditions such as preeclampsia may be caused by insufficient invasion and syncytialization of trophoblasts [17,18]. We explored the role of A1AT on the expression of inflammatory cytokines and syncytialization markers in human trophoblast cells using RNA-sequencing (RNA-seq) analysis
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