Identification of the role of DAB2 and CXCL8 in uterine spiral artery remodeling in early-onset preeclampsia.

Aberrant remodeling of uterine spiral arteries (SPA) is strongly associated with the pathogenesis of early-onset preeclampsia (EOPE). However, the complexities of SPA transformation remain inadequately understood. We conducted a single-cell RNA sequencing analysis of whole placental tissues derived from patients with EOPE and their corresponding controls, identified DAB2 as a key gene of interest and explored the mechanism underlying the communication between Extravillous trophoblast cells (EVTs) and decidual vascular smooth muscle cells (dVSMC) through cell models and a placenta-decidua coculture (PDC) model in vitro. DAB2 enhanced the motility and viability of HTR-8/SVneo cells. After exposure to conditioned medium (CM) from HTR-8/SVneoshNC cells, hVSMCs exhibited a rounded morphology, indicative of dedifferentiation, while CM-HTR-8/SVneoshDAB2 cells displayed a spindle-like morphology. Furthermore, the PDC model demonstrated that CM-HTR-8/SVneoshDAB2 was less conducive to vascular remodeling. Further in-depth mechanistic investigations revealed that C-X-C motif chemokine ligand 8 (CXCL8, also known as IL8) is a pivotal regulator governing the dedifferentiation of dVSMC. DAB2 expression in EVTs is critical for orchestrating the phenotypic transition and motility of dVSMC. These processes may be intricately linked to the CXCL8/PI3K/AKT pathway, underscoring its central role in intricate SPA remodeling.

Histone modifications in embryo implantation and placentation: insights from mouse models.

Embryo implantation and placentation play pivotal roles in pregnancy by facilitating crucial maternal-fetal interactions. These dynamic processes involve significant alterations in gene expression profiles within the endometrium and trophoblast lineages. Epigenetics regulatory mechanisms, such as DNA methylation, histone modification, chromatin remodeling, and microRNA expression, act as regulatory switches to modulate gene activity, and have been implicated in establishing a successful pregnancy. Exploring the alterations in these epigenetic modifications can provide valuable insights for the development of therapeutic strategies targeting complications related to pregnancy. However, our current understanding of these mechanisms during key gestational stages remains incomplete. This review focuses on recent advancements in the study of histone modifications during embryo implantation and placentation, while also highlighting future research directions in this field.

Generating Functional Multicellular Organoids from Human Placenta Villi.

The interaction between trophoblasts, stroma cells, and immune cells at the maternal-fetal interface constitutes the functional units of the placenta, which is crucial for successful pregnancy outcomes. However, the investigation of this intricate interplay is restricted due to the absence of efficient experimental models. To address this challenge, a robust, reliable methodology for generating placenta villi organoids (PVOs) from early, late, or diseased pregnancies using air-liquid surface culture is developed. PVOs contain cytotrophoblasts that can self-renew and differentiate directly, along with stromal elements that retain native immune cells. Analysis of scRNA sequencing and WES data reveals that PVOs faithfully recapitulate the cellular components and genetic alterations of the corresponding source tissue. Additionally, PVOs derived from patients with preeclampsia exhibit specific pathological features such as inflammation, antiangiogenic imbalance, and decreased syncytin expression. The PVO-based propagation of primary placenta villi should enable a deeper investigation of placenta development and exploration of the underlying pathogenesis and therapeutics of placenta-originated diseases.

JAZF1 safeguards human endometrial stromal cells survival and decidualization by repressing the transcription of G0S2.

Decidualization of human endometrial stromal cells (hESCs) is essential for the maintenance of pregnancy, which depends on the fine-tuned regulation of hESCs survival, and its perturbation contributes to pregnancy loss. However, the underlying mechanisms responsible for functional deficits in decidua from recurrent spontaneous abortion (RSA) patients have not been elucidated. Here, we observed that JAZF1 was significantly downregulated in stromal cells from RSA decidua. JAZF1 depletion in hESCs resulted in defective decidualization and cell death through apoptosis. Further experiments uncovered G0S2 as a important driver of hESCs apoptosis and decidualization, whose transcription was repressed by JAZF1 via interaction with G0S2 activator Purß. Moreover, the pattern of low JAZF1, high G0S2 and excessive apoptosis in decidua were consistently observed in RSA patients. Collectively, our findings demonstrate that JAZF1 governs hESCs survival and decidualization by repressing G0S2 transcription via restricting the activity of Purß, and highlight the clinical implications of these mechanisms in the pathology of RSA.

A critical role of RUNX1 in governing megakaryocyte-primed hematopoietic stem cell differentiation.

As a transcription factor in the RUNT domain core-binding factor family, RUNX1 is crucial in multiple stages of hematopoiesis, and its mutation can cause familial platelet disorder with a predisposition to acute myeloid leukemia. Previous work has established that RUNX1 is involved in the maturation of megakaryocytes (MKs) and the production of platelets. Recent studies have shown that there exists a subpopulation of hematopoietic stem cells (HSCs) with relatively high expression of von Willebrand factor and CD41 at the apex of the HSC hierarchy, termed MK-HSCs, which can give rise to MKs without going through the traditional differentiation trajectory from HSC via MPP (multipotent progenitors) and MEP (megakaryocyte-erythroid progenitor). Here, by using Runx1F/FMx1-Cre mouse model, we discovered that the MK-HSC to MK direct differentiation can occur within 1 cell division, and RUNX1 is an important regulator in the process. Runx1 knockout results in a drastic decrease in platelet counts and a severe defect in the differentiation from MK-HSCs to MKs. Single cell RNA sequencing (RNAseq) analysis shows that MK-HSCs have a distinct gene expression signature compared with non-MK-HSCs, and Runx1 deletion alters the platelet and MK-related gene expression in MK-HSCs. Furthermore, bulk RNAseq and Cut&Run analyses show that RUNX1 binds to multiple essential MK or platelet developmental genes, such as Spi1, Selp, and Itga2b and regulates their expressions in MK-HSCs. Thus, by modulating the expression of MK-related genes, RUNX1 governs the direct differentiation from MK-HSCs to MKs and platelets.

TNFα/TNFR1 signal induces excessive senescence of decidua stromal cells in recurrent pregnancy loss.

Defects in decidual response are associated with adverse pregnancy outcomes which includes recurrent pregnancy loss (RPL). It is reported that cellular senescence happens during decidualization and pro-senescent decidual response in the luteal phase endometrium is related to RPL. However, the underlying mechanisms of how excessive decidual senescence takes place in RPL decidua cells remain largely unexplored. The senescent phenotype of RPL decidua and tumor necrosis factor receptor 1(TNFR1) expression were analyzed by using our previously published single-cell sequencing dataset of decidua cells from 6 RPL and 5 matched normal decidua, which were further verified by PCR and WB in decidual tissues. Effects of TNFα on the decidual stromal cells (DSCs) senescence and underlying molecular pathways were analyzed using the in vitro decidualization model of human endometrial stromal cells (HESCs). We showed that decidual stroma cells from RPL patients exhibited transcriptomic features of cellular senescence by analysis of single-cell datasets. The TNFα level and TNFR1 expression were increased in RPL decidua tissues. Furthermore, in vitro cell model demonstrated that increased TNFα induced excessive senescence during decidualization and TNFR1/p53/p16 pathway mediates TNFα-induced stromal senescence. In addition, we also found that the expression of IGFBP1 was regulated by TNFα-TNFR1 interaction during decidualization. Taken together, the present findings suggest that the increased secretion of TNFα induced stromal cell excessive senescence in RPL decidua, which is mediated via TNFR1, and thus provide a possible therapeutic target for the treatment of RPL.

In vivo generation of bone marrow from embryonic stem cells in interspecies chimeras.

Generation of bone marrow (BM) from embryonic stem cells (ESCs) promises to accelerate the development of future cell therapies for life-threatening disorders. However, such approach is limited by technical challenges to produce a mixture of functional BM progenitor cells able to replace all hematopoietic cell lineages. Herein, we used blastocyst complementation to simultaneously produce BM cell lineages from mouse ESCs in a rat. Based on fluorescence-activated cell sorting analysis and single-cell RNA sequencing, mouse ESCs differentiated into multiple hematopoietic and stromal cell types that were indistinguishable from normal mouse BM cells based on gene expression signatures and cell surface markers. Receptor-ligand interactions identified Cxcl12-Cxcr4, Lama2-Itga6, App-Itga6, Comp-Cd47, Col1a1-Cd44, and App-Il18rap as major signaling pathways between hematopoietic progenitors and stromal cells. Multiple hematopoietic progenitors, including hematopoietic stem cells (HSCs) in mouse-rat chimeras derived more efficiently from mouse ESCs, whereas chondrocytes predominantly derived from rat cells. In the dorsal aorta and fetal liver of mouse-rat chimeras, mouse HSCs emerged and expanded faster compared to endogenous rat cells. Sequential BM transplantation of ESC-derived cells from mouse-rat chimeras rescued lethally irradiated syngeneic mice and demonstrated long-term reconstitution potential of donor HSCs. Altogether, a fully functional BM was generated from mouse ESCs using rat embryos as 'bioreactors'.

Role of ATP-dependent chromatin remodelers in hematopoietic stem and progenitor cell maintenance.

PURPOSE OF REVIEW: ATP-dependent chromatin remodeling factors utilize energy from ATP hydrolysis to modulate DNA-histone structures and regulate gene transcription. They are essential during hematopoiesis and for hematopoietic stem and progenitor cell (HSPC) function. This review discusses the recently unveiled roles of these chromatin remodelers in HSPC regulation, with an emphasis on the mechanism of chromodomain helicase DNA-binding (CHD) family members. RECENT FINDINGS: Recent studies of ATP-dependent chromatin remodelers have revealed that individual CHD family members engage in distinct mechanisms in regulating HSPC cell fate. For example, CHD8 is required for HSPC survival by restricting both P53 transcriptional activity and protein stability in steady state hematopoiesis while the related CHD7 physically interacts with RUNX family transcription factor 1 (RUNX1) and suppresses RUNX1-induced expansion of HSPCs during blood development. Moreover, other CHD subfamily members such as CHD1/CHD2 and CHD3/CHD4, as well as the switch/sucrose non-fermentable, imitation SWI, and SWI2/SNF2 related (SWR) families of chromatin modulators, have also been found important for HSPC maintenance by distinct mechanisms. SUMMARY: The expanding knowledge of ATP-dependent chromatin remodelers in hematopoiesis illustrates their respective critical roles in HSPC maintenance including the regulation of HSPC differentiation, survival, and self-renewal. Further studies are warranted to elucidate how different chromatin remodeling complexes are integrated in various HSPC cell fate decisions during steady-state and stress hematopoiesis.

Autism-associated chromatin remodeler CHD8 regulates erythroblast cytokinesis and fine-tunes the balance of Rho GTPase signaling.

CHD8 is an ATP-dependent chromatin-remodeling factor whose monoallelic mutation defines a subtype of autism spectrum disorders (ASDs). Previous work found that CHD8 is required for the maintenance of hematopoiesis by integrating ATM-P53-mediated survival of hematopoietic stem/progenitor cells (HSPCs). Here, by using Chd8F/FMx1-Cre combined with a Trp53F/F mouse model that suppresses apoptosis of Chd8-/- HSPCs, we identify CHD8 as an essential regulator of erythroid differentiation. Chd8-/-P53-/- mice exhibited severe anemia conforming to congenital dyserythropoietic anemia (CDA) phenotypes. Loss of CHD8 leads to drastically decreased numbers of orthochromatic erythroblasts and increased binucleated and multinucleated basophilic erythroblasts with a cytokinesis failure in erythroblasts. CHD8 binds directly to the gene bodies of multiple Rho GTPase signaling genes in erythroblasts, and loss of CHD8 results in their dysregulated expression, leading to decreased RhoA and increased Rac1 and Cdc42 activities. Our study shows that autism-associated CHD8 is essential for erythroblast cytokinesis.

The chromatin remodeler CHD8 governs hematopoietic stem/progenitor survival by regulating ATM-mediated P53 protein stability.

The Chd8 gene encodes a member of the chromodomain helicase DNA-binding (CHD) family of SNF2H-like adenosine triphosphate (ATP)-dependent chromatin remodeler, the mutations of which define a subtype of autism spectrum disorders. Increasing evidence from recent studies indicates that ATP-dependent chromatin-remodeling genes are involved in the control of crucial gene-expression programs in hematopoietic stem/progenitor cell (HSPC) regulation. In this study, we identified CHD8 as a specific and essential regulator of normal hematopoiesis. Loss of Chd8 leads to severe anemia, pancytopenia, bone marrow failure, and engraftment failure related to a drastic depletion of HSPCs. CHD8 forms a complex with ATM and its deficiency increases chromatin accessibility and drives genomic instability in HSPCs causing an activation of ATM kinase that further stabilizes P53 protein by phosphorylation and leads to increased HSPC apoptosis. Deletion of P53 rescues the apoptotic defects of HSPCs and restores overall hematopoiesis in Chd8-/- mice. Our findings demonstrate that chromatin organization by CHD8 is uniquely necessary for the maintenance of hematopoiesis by integrating the ATM-P53-mediated survival of HSPCs.

Adaptive responses to mTOR gene targeting in hematopoietic stem cells reveal a proliferative mechanism evasive to mTOR inhibition.

The mechanistic target of rapamycin (mTOR) is a central regulator of cell growth and an attractive anticancer target that integrates diverse signals to control cell proliferation. Previous studies using mTOR inhibitors have shown that mTOR targeting suppresses gene expression and cell proliferation. To date, however, mTOR-targeted therapies in cancer have seen limited efficacy, and one key issue is related to the development of evasive resistance. In this manuscript, through the use of a gene targeting mouse model, we have found that inducible deletion of mTOR in hematopoietic stem cells (HSCs) results in a loss of quiescence and increased proliferation. Adaptive to the mTOR loss, mTOR-/- HSCs increase chromatin accessibility and activate global gene expression, contrary to the effects of short-term inhibition by mTOR inhibitors. Mechanistically, such genomic changes are due to a rewiring and adaptive activation of the ERK/MNK/eIF4E signaling pathway that enhances the protein translation of RNA polymerase II, which in turn leads to increased c-Myc gene expression, allowing the HSCs to thrive despite the loss of a functional mTOR pathway. This adaptive mechanism can also be utilized by leukemia cells undergoing long-term mTOR inhibitor treatment to confer resistance to mTOR drug targeting. The resistance can be counteracted by MNK, CDK9, or c-Myc inhibition. These results provide insights into the physiological role of mTOR in mammalian stem cell regulation and implicate a mechanism of evasive resistance in the context of mTOR targeting.

Generation of Elf5-Cre knockin mouse strain for trophoblast-specific gene manipulation.

Placental development is a complex and highly controlled process during which trophoblast stem cells differentiate to various trophoblast subtypes. The early embryonic death of systemic gene knockout models hampers the investigation of these genes that might play important roles during placentation. A trophoblast specific Cre mouse model would be of great help for dissecting out the potential roles of these genes during placental development. For this purpose, we generate a transgenic mouse with the Cre recombinase inserted into the endogenous locus of Elf5 gene that is expressed specifically in placental trophoblast cells. To analyze the specificity and efficiency of Cre recombinase activity in Elf5-Cre mice, we mated Elf5-Cre mice with Rosa26mT/mG reporter mice, and found that Elf5-Cre transgene is expressed specifically in the trophoectoderm as early as embryonic day 4.5 (E4.5). By E12.5, the activity of Elf5-Cre transgene was detected exclusively in all derivatives of trophoblast lineages, including spongiotrophoblast, giant cells, and labyrinth trophoblasts. In addition, Elf5-Cre transgene was also active during spermatogenesis, from spermatids to mature sperms, which is consistent with the endogenous Elf5 expression in testis. Collectively, our results provide a unique tool to delete specific genes selectively and efficiently in trophoblast lineage during placentation.

Dual roles of TRF1 in tethering telomeres to the nuclear envelope and protecting them from fusion during meiosis.

Telomeres integrity is indispensable for chromosomal stability by preventing chromosome erosion and end-to-end fusions. During meiosis, telomeres attach to the inner nuclear envelope and cluster into a highly crowded microenvironment at the bouquet stage, which requires specific mechanisms to protect the telomeres from fusion. Here, we demonstrate that germ cell-specific knockout of a shelterin complex subunit, Trf1, results in arrest of spermatocytes at two different stages. The obliterated telomere-nuclear envelope attachment in Trf1-deficient spermatocytes impairs homologue synapsis and recombination, resulting in a pachytene-like arrest, while the meiotic division arrest might stem from chromosome end-to-end fusion due to the failure of recruiting meiosis specific telomere associated proteins. Further investigations uncovered that TRF1 could directly interact with Speedy A, and Speedy A might work as a scaffold protein to further recruit Cdk2, thus protecting telomeres from fusion at this stage. Together, our results reveal a novel mechanism of TRF1, Speedy A, and Cdk2 in protecting telomere from fusion in a highly crowded microenvironment during meiosis.

Distinct TERB1 Domains Regulate Different Protein Interactions in Meiotic Telomere Movement.

Meiotic telomeres attach to the nuclear envelope (NE) and drive the chromosome movement required for the pairing of homologous chromosomes. The meiosis-specific telomere proteins TERB1, TERB2, and MAJIN are required to regulate these events, but their assembly processes are largely unknown. Here, we developed a germ-cell-specific knockout mouse of the canonical telomere-binding protein TRF1 and revealed an essential role for TRF1 in directing the assembly of TERB1-TERB2-MAJIN. Further, we identified a TERB2 binding (T2B) domain in TERB1 that is dispensable for the TRF1-TERB1 interaction but is essential for the subsequent TERB1-TERB2 interaction and therefore for telomere attachment to the NE. Meanwhile, cohesin recruitment at telomeres, which is required for efficient telomere movement, is mediated by the MYB-like domain of TERB1, but not by TERB2-MAJIN. Our results reveal distinct protein interactions through various domains of TERB1, which enable the sequential assembly of the meiotic telomere complex for their movements.

MASTL is essential for anaphase entry of proliferating primordial germ cells and establishment of female germ cells in mice.

In mammals, primordial germ cells (PGCs) are the embryonic cell population that serve as germ cell precursors in both females and males. During mouse embryonic development, the majority of PGCs are arrested at the G2 phase when they migrate into the hindgut at 7.75-8.75 dpc (days post coitum). It is after 9.5 dpc that the PGCs undergo proliferation with a doubling time of 12.6 h. The molecular mechanisms underlying PGC proliferation are however not well studied. In this work. Here we studied how MASTL (microtubule-associated serine/threonine kinase-like)/Greatwall kinase regulates the rapid proliferation of PGCs. We generated a mouse model where we specifically deleted Mastl in PGCs and found a significant loss of PGCs before the onset of meiosis in female PGCs. We further revealed that the deletion of Mastl in PGCs did not prevent mitotic entry, but led to a failure of the cells to proceed beyond metaphase-like stage, indicating that MASTL-mediated molecular events are indispensable for anaphase entry in PGCs. These mitotic defects further led to the death of Mastl-null PGCs by 12.5 dpc. Moreover, the defect in mitotic progression observed in the Mastl-null PGCs was rescued by simultaneous deletion of Ppp2r1a (α subunit of PP2A). Thus, our results demonstrate that MASTL, PP2A, and therefore regulated phosphatase activity have a fundamental role in establishing female germ cell population in gonads by controlling PGC proliferation during embryogenesis.

Speedy A-Cdk2 binding mediates initial telomere-nuclear envelope attachment during meiotic prophase I independent of Cdk2 activation.

Telomere attachment to the nuclear envelope (NE) is a prerequisite for chromosome movement during meiotic prophase I that is required for pairing of homologous chromosomes, synapsis, and homologous recombination. Here we show that Speedy A, a noncanonical activator of cyclin-dependent kinases (Cdks), is specifically localized to telomeres in prophase I male and female germ cells in mice, and plays an essential role in the telomere-NE attachment. Deletion of Spdya in mice disrupts telomere-NE attachment, and this impairs homologous pairing and synapsis and leads to zygotene arrest in male and female germ cells. In addition, we have identified a telomere localization domain on Speedy A covering the distal N terminus and the Cdk2-binding Ringo domain, and this domain is essential for the localization of Speedy A to telomeres. Furthermore, we found that the binding of Cdk2 to Speedy A is indispensable for Cdk2's localization on telomeres, suggesting that Speedy A and Cdk2 might be the initial components that are recruited to the NE for forming the meiotic telomere complex. However, Speedy A-Cdk2-mediated telomere-NE attachment is independent of Cdk2 activation. Our results thus indicate that Speedy A and Cdk2 might mediate the initial telomere-NE attachment for the efficient assembly of the telomere complex that is essential for meiotic prophase I progression.

FoxM1 Directs STAT3 Expression Essential for Human Endometrial Stromal Decidualization.

Human endometrium decidualization, which involves endometrial stromal proliferation and differentiation, is a prerequisite for embryo implantation, thus successful pregnancy. The Forkhead Box M1 (FoxM1), previously known as HNF-3, HFH-11, MPP2, Win, and Trident, is a transcriptional factor that plays crucial roles in cell proliferation and cell cycle progression. However, the molecular mechanism of FoxM1 during human endometrial decidualization remains unexplored. In this study, we first found FoxM1 is dynamically expressed in human endometrium during menstrual cycle. Employing a human endometrial stromal cell (HESC) line, we then demonstrated that FoxM1 inhibition downregulates cyclin B1 expression, delaying G2/M phase transition during HESC proliferation. Additionally, loss of FoxM1 expression blocks the differentiation of HESCs in response to estrogen, progesterone, and dbcAMP. Applying chromatin immunoprecipitation (ChIP) technique and luciferase assay, we further approved that FoxM1 can transcriptionally active signal transducer and activator of transcription 3 (STAT3), ensuring normal HESC differentiation. Besides enriching our knowledge on molecular basis underlying stromal decidualization, these findings help to shed light on the potential molecular causes for the endometrial disorders in humans.

NEDD8-mediated neddylation is required for human endometrial stromal proliferation and decidualization.

STUDY QUESTION: Does NEDD8-mediated neddylation regulate human endometrial stromal proliferation and decidualization? SUMMARY ANSWER: Neddylation inhibition by a selective NEDD8-activating enzyme inhibitor, MLN4924, significantly impairs human endometrial stromal cell (HESC) proliferation and decidualization and facilitates cell senescence, via p21 accumulation. WHAT IS KNOWN ALREADY: Neddylation regulates cell proliferation and tissue remodeling during embryogenesis and tumorigenesis, while human endometrial stroma undergoes sequential proliferation, differentiation, as well as dynamic tissue remodeling during each menstrual cycle. STUDY DESIGN, SIZE, DURATION: We first analyzed the expression of NEDD8 in human endometrial tissues from 50 subjects, and then explored the consequence of neddylation inhibition by MLN4924 on HESCs proliferation, decidualization and cellular senescence. PARTICIPANTS/MATERIALS, SETTING, METHODS: We collected 50 dated human endometrial tissues from early proliferative stage to late secretory phase of the menstrual cycle and analyzed the NEDD8 expression and cellular location in human endometrium by employing quantitative real-time PCR (qRT-PCR) and immunohistochemistry staining. Similar approaches were also used to explore the mRNA and protein expression of NEDD8 in an immortalized human endometrial stromal cell line (HESC) during proliferation and decidualization (N = 6). An MTS assay was performed to evaluate the effects of neddylation inhibition by MLN4924 on HESC proliferation. Flow cytometry and BrdU incorporation assay were conducted to determine the HESC cell cycle progression in response to MLN4924 exposure during proliferation. We also analyzed F-actin distribution by phalloidin staining and decidual marker gene expression by qRT-PCR to accesses the consequence of neddylation inhibition on HESC decidualization. Immunoblotting analysis of cullin1 and p21, and SA-ß-Galactosidase staining were performed to reveal the potential molecular basis for the impaired HESC proliferation, decidualization and cellular senescence. The siRNA technique was applied to knockdown p21 expression to test whether a clearance of p21 accumulation would correct the HESC defects from neddylation inhibition. MAIN RESULTS AND THE ROLE OF CHANCE: We demonstrated that NEDD8 is ubiquitously expressed in human endometrium including luminal epithelium, glandular epithelium and the stromal cells during the menstrual cycle, as well as in the HESCs during proliferation and differentiation in culture. Employing multiple molecular, cellular and pharmacological approaches, we further observed that neddylation inhibition by MLN4924 significantly attenuates HESC proliferation (P-value < 0.05), impairs decidual transformation (P-value < 0.05), and facilitates cellular senescence. These abnormal HESC activities upon MLN4924 exposure were accompanied with reduced cullin1 neddylation and an aberrant accumulation of p21. While a clearance of p21 accumulation by siRNA knockdown could partially restore HESC proliferation and cellular viability, it failed to correct the decidualization defects. LIMITATIONS, REASONS FOR CAUTION: Since NEDD8 was also intensely expressed in the endometrial epithelium, it is interesting to further study its potential role in stroma-epithelial interactions through isolating and culturing epithelial cells. p21 siRNA knockdown experiments revealed that there are differential molecular machineries, other than p21, that are subject to neddylation regulation during HESC proliferation compared with differentiation. This alternative mechanism warrants further investigation in future. WIDER IMPLICATIONS OF THE FINDINGS: Our findings add novel evidence showing, for what we believe the first time, that NEDD8-mediated neddylation is required for normal human endometrial functions, which raises the possibility of approaching the neddylation system for diagnosis and treatment of infertility in women. STUDY FUNDING/COMPETING INTERESTS: This work was supported in parts by the National Basic Research Program of China (2011CB944400 to H.W.) and the National Natural Science Foundation (81130009, 81330017 to H.W., 81170575 to S.Q. and 31471106 to S.Z.). The author declares that there is no conflict of interest.

Molecular determinants of uterine receptivity.

Uterine receptivity is defined as a limited period when the uterine environment is conducive to blastocyst acceptance and implantation. Any disturbance of this early pregnancy event will compromise pregnancy success. In this review, we first briefly summarize uterine morphological coordination for the attainment of receptivity, then focus on elucidating the molecular complexity in establishing uterine receptivity and hence embryo implantation. A better understanding of the molecular basis governing uterine receptivity will help to improve the outcome of natural pregnancy and pregnancy conceived via assisted reproductive techniques.

Integral proteomic analysis of blastocysts reveals key molecular machinery governing embryonic diapause and reactivation for implantation in mice.

Among nearly 100 mammalian species, implantation can be suspended at blastocyst stage for a certain time and reactivated under favorable conditions, a phenomenon known as embryonic diapause. Until now, the underlying molecular mechanism governing embryonic diapause and reactivation for implantation remained largely unknown. Here we conducted the first integral proteomic analysis of blastocysts from diapause to reactivation by using a physiologically relevant mouse delayed implantation model. More than 6000 dormant and reactivated blastocysts were used for the proteomic analysis. A total of 2255 proteins were detected. Various cellular and molecular processes, including protein translation, aerobic glycolysis, pentose phosphate pathway, purine nucleotide biosynthesis, glutathione metabolism, and chromatin organization were identified as differentially regulated. In particular, we demonstrated a remarkable activation of mitochondria in blastocysts upon reactivation from dormancy, highlighting their essential physiological significance. Moreover, the activities of the endosome-lysosome system were prominently enhanced in the mural trophectoderm of reactivated blastocysts, accompanied by active phagocytosis at the fetal-maternal interface, suggesting a critical role in promoting trophoblast invasion. Collectively, we provided an integral proteomic view upon the regulatory network of blastocyst reactivation from diapause, which will help to better interpret the nature of embryonic diapause and reactivation in wild animals and to identify molecular indicators for selecting blastocysts with high implantation competency.