Uterine Notch2 facilitates pregnancy recognition and corpus luteum maintenance via upregulating decidual Prl8a2

Axl deficiency promotes preeclampsia and vascular malformations in mice

Preeclampsia (PE) is a significant complication of pregnancy, occurring in approximately 10% of pregnancies. However, the underlying mechanisms of this condition remain unclear. Placentation and tumorigenesis both share many characteristics, but PE is the result of insufficient placentation, in contrast to the overaggression of tumorigenesis. AXL is a biomarker and therapeutic target for multiple metastatic cancers. We hypothesized that its downregulation could play a crucial role in the development of PE. In our study, we demonstrated that pregnant Axl -/- mice exhibited typical PE symptoms, such as hypertension, proteinuria, and inadequate trophoblast invasion and spiral artery remodeling. Cross-mating and embryo transplantation experiments confirmed that these phenotypes were caused by the decidua. RNA sequencing results revealed the abnormal expression of several transcripts in the decidua, including Corin, which encodes a cardiac protease responsible for activating atrial natriuretic peptide (ANP). ANP is a cardiac hormone that regulates sodium homeostasis and blood pressure. Chromatin immunoprecipitation-qPCR analysis indicated that the decreased CORIN in Axl -/- decidua was due to reduced signal transducer and activator of transcription 3 (STAT3) binding. Treatment with ANP successfully alleviated the PE symptoms. Furthermore, we observed that in PE decidua, the level of AXL was significantly lower compared to normal pregnancies. These findings suggest that the dysregulation of decidua-derived AXL-CORIN-ANP signaling disrupts maternal-fetal crosstalk and contributes to the development of PE.

Ovarian expression of MerTK and its ligand Pros1 in non-pregnant estrus and pregnant mice

AIM

The interaction of MerTK, which negatively regulates immune responses, with its ligand Pros1 contributes to the resolution of apoptosis and inflammation, participating in the healing process of tissues. The levels of MerTK and Pros1, intensely expressed in macrophages (Mϕs), are affected by sex hormones. The expression levels of these proteins in Mϕs, which have a role in corpus luteum (CL) development or regression and folliculogenesis, were investigated in this study since their expressions have not been evaluated in pregnant mouse ovaries.

METHOD

We analyzed mouse ovaries from non-pregnant mice at estrus and gestation days 5, 8, and 15 (each n:10). We used qPCR to evaluate Mertk and Pros1 mRNA levels and assessed their protein expression and localization using immunohistochemistry and double immunofluorescence staining for co-localization.

RESULTS

Mertk and Pros1 mRNA and protein levels significantly increased in GD15. MerTK and Pros1 protein levels in mouse CL on GD15 were significantly higher than all other groups. MerTK and Pros1 positive Mϕs were observed in CL of GD15 by double immunofluorescence. MerTK protein levels were increased in granulosa cells GD15 of primary and growing follicles.

CONCLUSION

Our study revealed for the first time that the expression of MerTK and Pros1 was significantly increased in CL at GD15 in mice. These results suggest that increased levels of MerTK andPros1 may enhance their interaction as receptor-ligand binding partners in CL potentially contributing to the balance of apoptosis and inflammation.

GWAS of Reproductive Traits in Large White Pigs on Chip and Imputed Whole-Genome Sequencing Data

Total number born (TNB), number of stillborn (NSB), and gestation length (GL) are economically important traits in pig production, and disentangling the molecular mechanisms associated with traits can provide valuable insights into their genetic structure. Genotype imputation can be used as a practical tool to improve the marker density of single-nucleotide polymorphism (SNP) chips based on sequence data, thereby dramatically improving the power of genome-wide association studies (GWAS). In this study, we applied Beagle software to impute the 50 K chip data to the whole-genome sequencing (WGS) data with average imputation accuracy (R2) of 0.876. The target pigs, 2655 Large White pigs introduced from Canadian and French lines, were genotyped by a GeneSeek Porcine 50K chip. The 30 Large White reference pigs were the key ancestral individuals sequenced by whole-genome resequencing. To avoid population stratification, we identified genetic variants associated with reproductive traits by performing within-population GWAS and cross-population meta-analyses with data before and after imputation. Finally, several genes were detected and regarded as potential candidate genes for each of the traits: for the TNB trait: NOTCH2, KLF3, PLXDC2, NDUFV1, TLR10, CDC14A, EPC2, ORC4, ACVR2A, and GSC; for the NSB trait: NUB1, TGFBR3, ZDHHC14, FGF14, BAIAP2L1, EVI5, TAF1B, and BCAR3; for the GL trait: PPP2R2B, AMBP, MALRD1, HOXA11, and BICC1. In conclusion, expanding the size of the reference population and finding an optimal imputation strategy to ensure that more loci are obtained for GWAS under high imputation accuracy will contribute to the identification of causal mutations in pig breeding.

BMP/SMAD1/5 Signaling in the Endometrial Epithelium Is Essential for Receptivity and Early Pregnancy

The biological processes that control endometrial receptivity and embryo implantation are critical for the successful outcome of pregnancy. The endometrium is the complex inner lining of the uterine wall that is under the cyclical control of estrogen and progesterone and is a site of intimate contact between mother and blastocyst. The bone morphogenetic signaling (BMP) pathway is a highly conserved signaling pathway that controls key cellular processes throughout pregnancy and exerts intracellular effects via the SMAD1/5 transcription factors. To delineate the endometrial compartment-specific roles of BMP signaling, we generated mice with epithelial-specific conditional deletion of SMAD1/5 using Lactoferrin-icre (Smad1flox/flox;Smad5flox/flox;Lactoferrin-cre, "Smad1/5 cKO"). Histological analysis of the reproductive tracts showed that Smad1/5 cKO mice were developmentally normal and displayed no defects in glandular morphology. In fertility analyses, single SMAD1 or SMAD5 deletion had no effect on fertility; however, double-conditional deletion of SMAD1 and SMAD5 resulted in severe subfertility. Timed mating analyses revealed endometrial receptivity defects in the Smad1/5 cKO mice beginning at 3.5 days post coitum (dpc) that perturbed embryo implantation at 4.5 dpc, as demonstrated by the detection of unattached blastocysts in the uterus, decreased COX2 expression, and FOXO1 cytoplasmic mislocalization. We also found that defects that arose during peri-implantation adversely affected embryonic and decidual development at 5.5 and 6.5 dpc. Thus, uterine epithelial BMP/SMAD1/5 signaling is essential during early pregnancy and SMAD1/5 epithelial-specific deletion has detrimental effects on stromal cell decidualization and pregnancy development.