miR-23a-3p increases endometrial receptivity via CUL3 during embryo implantation

A receptive endometrium is required in a successful embryo implantation. The ubiquitination-induced β-catenin degradation is related to the implantation failure.This study aimed to elucidate whether miR-23a-3p regulates endometrial receptivity via the modulation of β-catenin ubiquitination.The expressions of miR-23a-3p and CUL3 were detected in endometrial epithelial cells (EECs) isolated from pregnant mice and in hormone-induced EEC-like Ishikawa cells. The ubiquitination experiment was performed to explore the effect of CUL3 and miR-23a-3p on β-catenin ubiquitination level. The trophoblast attachment was detected by co-culturing JAR (choriocarcinoma cell line) spheroids with Ishikawa cell monolayers. miR-23a-3p was upregulated while CUL3 was downregulated in EECs at day 4 after pregnancy compared with day 1, as well as in hormone-induced Ishikawa cells. miR-23a-3p positively regulated the protein level of β-catenin without affecting the mRNA level. The ubiquitination and degradation of β-catenin was suppressed by miR-23a-3p, while it was promoted by CUL3. Immunoprecipitation confirmed the binding between CUL3 and β-catenin. Luciferase reporter assay confirmed the target relationship between miR-23a-3p and CUL3. The ubiquitination of β-catenin was modulated by the miR-23a-3p/CUL3 pathway. The overexpression of miR-23a-3p promoted JAR spheroid attachments in Ishikawa cells. miR-23a-3p is beneficial for the endometrial receptivity and embryo implantation, whose mechanism is partly through the modulation of CUL3/β-catenin.

Molecular underpinning of intracellular pH regulation on TMEM16F

TMEM16F, a dual functional phospholipid scramblase and ion channel, is important in blood coagulation, skeleton development, HIV infection and cell fusion. Despite the advances in understanding its structure and activation mechanism, how TMEM16F is regulated by intracellular factors remains largely elusive. Here we report that TMEM16F lipid scrambling and ion channel activities are strongly influenced by intracellular pH (pHi). We find that low pHi attenuates whereas high pHi potentiates TMEM16F activation. Our biophysical characterizations pinpoint that the pHi regulatory effects on TMEM16F stem from protonation and deprotonation of the Ca2+ binding sites, which in turn reduces and enhances Ca2+ binding affinity, respectively. We further demonstrate that intracellular alkalization of 0.5 pHi can significantly promote TMEM16F activities in a choriocarcinoma cell line. Our findings thus uncover a regulatory mechanism of TMEM16F by pHi and shine light on understanding the pathophysiological roles of TMEM16F in diseases with dysregulated pHi including cancer.

Eutherian-Specific Gene TRIML2 Attenuates Inflammation in the Evolution of Placentation

Evolution of highly invasive placentation in the stem lineage of eutherians and subsequent extension of pregnancy set eutherians apart from other mammals, that is, marsupials with short-lived placentas, and oviparous monotremes. Recent studies suggest that eutherian implantation evolved from marsupial attachment reaction, an inflammatory process induced by the direct contact of fetal placenta with maternal endometrium after the breakdown of the shell coat, and shortly before the onset of parturition. Unique to eutherians, a dramatic downregulation of inflammation after implantation prevents the onset of premature parturition, and is critical for the maintenance of gestation. This downregulation likely involved evolutionary changes on maternal as well as fetal/placental side. Tripartite-motif family-like2 (TRIML2) only exists in eutherian genomes and shows preferential expression in preimplantation embryos, and trophoblast-derived structures, such as chorion and placental disc. Comparative genomic evidence supports that TRIML2 originated from a gene duplication event in the stem lineage of Eutheria that also gave rise to eutherian TRIML1. Compared with TRIML1, TRIML2 lost the catalytic RING domain of E3 ligase. However, only TRIML2 is induced in human choriocarcinoma cell line JEG3 with poly(I:C) treatment to simulate inflammation during viral infection. Its knockdown increases the production of proinflammatory cytokines and reduces trophoblast survival during poly(I:C) stimulation, while its overexpression reduces proinflammatory cytokine production, supporting TRIML2’s role as a regulatory inhibitor of the inflammatory pathways in trophoblasts. TRIML2’s potential virus-interacting PRY/SPRY domain shows significant signature of selection, suggesting its contribution to the evolution of eutherian-specific inflammation regulation during placentation.

HIF-1α Activation Reduces Expression of the microRNA hsa-miR-603 Host Gene KIAA1217 and Increases Expression of the Target CCND1 Gene in BeWo b30 Cells

The model of the placental barrier based on the human choriocarcinoma cell line BeWo b30 allows studying the effect of hypoxia on trophoblast cells. The effect of the oxyquinoline derivative inhibiting HIF-prolyl hydroxylases was studied on this model. Inhibition of these enzymes leads to an increase in the HIF-1α subunit in the cytoplasm, mimicking the cell response to hypoxia. Incubation of the cells with the drug at a concentration of 10 uM for 24 h did not affect the paracellular transport, but reduced the transport of glucose through the cell barrier. The transcriptome analysis after the exposure with oxyquinoline derivative revealed a decreased expression of the KIAA1217 gene and its intronic gene MIR603, which encodes microRNA hsa-miR-603. The expression of the target gene of this miRNA, CCND1 encoding cyclin D1, after oxyquinoline derivative exposition increased significantly, which may indicate a potential microRNA-mRNA regulatory mechanism in the response of trophoblast cells to hypoxia. BeWo b30, placenta, hypoxia, oxyquinoline, barrier, microRNA, cyclin The study was performed with the equipment of the «Postgenomic and Metabolomic Methods of Study in Molecular Biology» Common Use Center (BioClinicum Scientific and Technical Center). The study was supported by the Ministry of Education and Science of the Russian Federation in the framework of the Federal Targeted Program for Research and Development in Priority Areas of Advancement of the Russian Scientific and Technological Complex for 2014-2020 (Project no. RFMEFI58817X0007).