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

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.