PADI6 Regulates Trophoblast Cell Migration-Invasion Through the Hippo/YAP1 Pathway in Hydatidiform Moles

Mechanisms of YAP1-mediated trophoblast ferroptosis in recurrent pregnancy loss

PURPOSE

The purpose of our study is to investigate the function of YAP1 in the trophoblast ferroptosis and maternal-fetal interface communication of RPL.

METHODS

We collected 25 villous tissues and detected the expression of YAP1. Cell counting kit-8 assay, scratch wound-healing assay, and Matrigel invasion assay were performed to observe the proliferation, migration, and invasion of HTR-8/SVneo and JAR cells. Subsequently, measured the levels of reactive oxygen species (ROS), malondialdehyde (MDA), reduced glutathione (GSH), SLC7A11, SOD2, and GPX4. Ultimately, the use of ferroptosis activator (erastin) and inhibitor (Ferrostatin-1, fer-1) further confirmed the regulation by YAP1. In addition, established an in vitro-induced cell model to study the effect of YAP1 on the decidualization process. Finally, animal models were implemented for further confirmation.

RESULTS

We found that YAP1 was downregulated in RPL patients. Overexpression of YAP1 could significantly enhance the proliferation, migration, and invasion of trophoblasts, and inhibit ferroptosis. Knocking down YAP1 exhibited the opposite effect. Rescue experiments have shown that YAP1 could upregulate the expression of SLC7A11 and GPX4, which are key molecules in the classic pathway of ferroptosis. In addition, the decidualization was impaired when hESCs were treated with conditioned medium of YAP1 knockdown trophoblasts. Moreover, we found that Yap1, Slc7a11, and Gpx4 were downregulated in the RPL mice, along with increased MDA and decreased GSH.

CONCLUSION

Downregulation of YAP1 induces ferroptosis, thereby damaging the trophoblast invasion processes, which also disturbs the communication at the maternal-fetal interface. Our study identified YAP1 as a potential key molecule in the pathogenesis of RPL.

PADI6: What we know about the elusive fifth member of the peptidyl arginine deiminase family

Peptidyl arginine deiminase 6 (PADI6) is a maternal factor that is vital for early embryonic development. Deletion and mutations of its encoding gene in female mice or women lead to early embryonic developmental arrest, female infertility, maternal imprinting defects and hyperproliferation of the trophoblast. PADI6 is the fifth and least well-characterized member of the peptidyl arginine deiminases (PADIs), which catalyse the post-translational conversion of arginine to citrulline. It is less conserved than the other PADIs, and currently has no reported catalytic activity. While there are many suggested functions of PADI6 in the early mouse embryo, including in embryonic genome activation, cytoplasmic lattice formation, maternal mRNA and ribosome regulation, and organelle distribution, the molecular mechanisms of its function remain unknown. In this review, we discuss what is known about the function of PADI6 and highlight key outstanding questions that must be answered if we are to understand the crucial role it plays in early embryo development and female fertility. This article is part of the Theo Murphy meeting issue 'The virtues and vices of protein citrullination'.

A novel homozygous variant in PADI6 is associate with human cleavage-stage embryonic arrest

Repeated absence of useable embryos is a difficult problem for infertility patients. Among them, embryonic developmental arrest is more common, but the genetic cause is not known. The embryos of a patient who came to our hospital three times could not develop beyond the four-cell stage. In addition to recording the developmental details of the embryos by daily photo-taking, the PADI6 R132C homozygous variants was further confirmed by whole-exome sequencing. Subsequently, PADI6 R132C was analyzed by bioinformatics methods for conservativeness across species. In addition, the possible impact of the pathogenic mutation on the structure of the protein PADI6 were also assessed. Generally, we identified a homozygous variants [NM_207421.4, c.394C>T(p.R132C] in the middle protein-arginine deiminase domain in PADI6 gene. The homozygous variant is highly conserved across species. Homozygous variant in PADI6 R132C could cause a human cleavage-stage embryonic arrest in female patients. These findings provide further evidence for the important roles of the homozygous PADI6R132C variant in embryonic development. Our findings contribute to a deeper understanding of the molecular genetic basis of female infertility.

Role of the PADI family in inflammatory autoimmune diseases and cancers: A systematic review

The peptidyl arginine deiminase (PADI) family is a calcium ion-dependent group of isozymes with sequence similarity that catalyze the citrullination of proteins. Histones can serve as the target substrate of PADI family isozymes, and therefore, the PADI family is involved in NETosis and the secretion of inflammatory cytokines. Thus, the PADI family is associated with the development of inflammatory autoimmune diseases and cancer, reproductive development, and other related diseases. In this review, we systematically discuss the role of the PADI family in the pathogenesis of various diseases based on studies from the past decade to provide a reference for future research.

PAD4-dependent citrullination of nuclear translocation of GSK3β promotes colorectal cancer progression via the degradation of nuclear CDKN1A

Peptidylarginine deiminase 4 (PAD4), a Ca²⁺-dependent enzyme, catalyzes the conversion of arginine to citrulline and has been strongly associated with many malignant tumors. However, the molecular mechanisms of PAD4 in the development and progression of colorectal cancer (CRC) remain unclearly defined. In our study, PAD4 expression was increased in CRC tissues and cells, and was closely related to tumor size, lymph node metastasis. Moreover, the transcription factor KLF9 directly bound to PADI4 gene promoter, leading to overexpression of PAD4 in CRC cells, which augmented cell growth and migration. We revealed that PAD4 interacted with and citrullinated glycogen synthase kinase-3β (GSK3β) in CRC cells, and GSK3β Arg-344 was the dominating PAD4-citrullination site. Furthermore, IgL2 and catalytic domains of PAD4 directly bound to the kinase domain of GSK3β in CRC cells. Mechanistically, PAD4 promoted the transport of GSK3β from the cytoplasm to the nucleus, thereby increasing the ubiquitin-dependent proteasome degradation of nuclear cyclin-dependent kinase inhibitor 1 (CDKN1A). Our study is the first to reveal the details of a critical PAD4/GSK3β/CDKN1A signaling axis for CRC progression, and provides evidence that PAD4 is a potential diagnosis biomarker and therapeutic target in CRC.

Molecular regulation of trophoblast stem cell self-renewal and giant cell differentiation by the Hippo components YAP and LATS1

Background

Trophoblast stem cells (TSCs), the precursors of trophoblast cells of placenta, possess the potential to differentiate into various trophoblastic subtypes in vitro. Establishment of extraembryonic trophoblastic lineage is preceded by the “outside versus inside” positional information in preimplantation embryos, critically synchronized by the Hippo components. Abundant expression of Hippo effector YAP in TSCs and differentiated cells with paucity of information on Hippo regulation of TSC proliferation/differentiation led us test the hypothesis that Hippo dynamics is one of the regulators of  TSC proliferation/differentiation.

Methods

Blastocyst-derived murine TSCs were used. Dynamics of Hippo components were analyzed using immunofluorescence, western blotting, immunoprecipitation, qRT-PCR. Interaction studies were performed using full-length and deletion constructs. BrdU incorporation assay, flow cytometry-based polyploidy analysis and confocal microscopy were used to decipher the underlying mechanism.

Results

YAP translocates to the nucleus in TSCs and utilizes its WW₂ domain to interact with the PPQY motif of the stemness factor, CDX2. YAP limits TSC proliferation with associated effect on CDX2 target CyclinD1. Trophoblast giant cells (TGC) differentiation is associated with cytoplasmic retention of YAP, heightened pYAP^Ser127, decrease in the level of the core Hippo component, LATS1, which thereby impedes LATS1-LIMK2 association. Decreased LATS1-LIMK2 complex formation in TGCs was associated with elevated pLIMK2^Thr505 as well as its target pCOFILIN^Ser3. Precocious overexpression of LATS1 during trophoblast differentiation decreased TGC marker, Prl2c2, diminished pLIMK2^Thr505 and inactive COFILIN (pCOFILIN^Ser3) while COFILIN-phosphatase, CHRONOPHIN remained unchanged. LATS1 overexpression inhibited trophoblast endoreduplication with smaller-sized TGC-nuclei, lower ploidy level and disintegrated actin filaments. Inhibition of LIMK2 activity recapitulated the effects of LATS1 overexpression in trophoblast cells.

Conclusion

These results unveil a multilayered regulation of trophoblast self-renewal and differentiation by the Hippo components.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-022-02844-w.