BMP15 regulates FSHR through TGF-β receptor II and SMAD4 signaling in prepubertal ovary of Rongchang pigs

Integrative genomic analysis reveals shared loci for reproduction and production traits in Yorkshire pigs

BACKGROUND

Improving reproductive performance in Yorkshire pigs, a key maternal line in three-way crossbreeding systems, remains challenging due to low heritability and historical selection pressures favoring production traits. Identifying pleiotropic genetic variants that influence both reproduction and production traits is crucial for understanding their genetic interplay and enhancing molecular breeding strategies.

RESULTS

Genome-wide association studies (GWAS) using 2,764 individuals identified 264,660 significant loci associated with reproduction traits and 12,460 loci for production traits, with 73 independent signals, including genes such as SCLT1 and CAPN9. A total of 465,047 independent loci were identified, resulting in a genome-wide significance threshold of 2.15 × 10 - 6 . Genetic correlations analysis between reproduction and production traits across parities revealed varying trends, including a strengthening negative correlation between mean litter weight (MLW) and backfat thickness (BFT) with increasing parity (P1: r g =-0.0376; P2: r g =-0.1371; P3: r g =-0.1475). Given 1062 shared significant loci between MLW and BFT, local genetic correlation was calculated within the corresponding genomic regions, resulting in a weak correlation of 0.014. Transcriptome-wide association studies (TWAS) leveraging data from the PigGTEx project, which includes 9,530 RNA-sequencing samples across 34 tissues, revealed 2,143 significant genes, with 31 linked to total number of piglets born (TNB) and 133 to number of piglets born alive (NBA). These results highlight the importance of these genes in reproductive performance, with SCLT1 being notably significant in reproductive tissues. For MLW, integrating results from multiple analyses revealed CENPE as a strong candidate gene, exhibiting significant association and colocalization. Validation in an independent population (n = 300) showed that incorporating the top 0.2% of significant single nucleotide polymorphisms (SNPs) in the GFBLUP model improved predictive accuracy, increasing from 0.0168 to 0.0242 for MLW.

CONCLUSION

This study provides new insights into the pleiotropic genetic architecture underlying reproduction and production traits in Yorkshire pigs. Genetic correlations, shared loci, and candidate genes inform breeding program design. The increased accuracy of genomic selection using these significant loci highlights their practical utility in improving breeding efficiency. These findings suggest opportunities for refining selection strategies, although further research is warranted to fully realize their potential for enhancing breeding programs.

Smad4 and FoxH1 potentially interact to regulate cyp19a1a promoter in the ovary of ricefield eel (Monopterus albus)

BACKGROUND

Cyp19a1a is a key enzyme in the pathway that converts androgens into estrogen and is regulated by TGF-β signaling. Smad4 and FoxH1 are downstream effectors of TGF-β signaling and may play important roles in ovarian development in M. albus.

METHODS

We investigated the expression pattern of the Smad4 and FoxH1 using qRT‒PCR and immunofluorescence, then tested the changes of smad4 and foxh1 by qRT‒PCR after ovary incubation with FSH in vitro, and analysed the regulation of cyp19a1a transcription by Smad4 and FoxH1 by dual-luciferase reporter assays.

RESULTS

We found that Smad4 encoded a putative protein of 449 amino acids and harbored the three conserved domains typical of this protein family. Smad4 and foxh1 exhibited similar expression patterns during ovarian development and after FSH incubation, with Pearson's coefficients of 0.873 and 0.63-0.81, respectively. Furthermore, Smad4, FoxH1 and Cyp19a1a colocalized in the granulosa cells and theca cells of ovaries during the mid-to-late vitellogenic stage. Smad4 repressed cyp19a1a activity via SBE1 (- 1372/-1364) and SBE2 (- 415/-407) in the cyp19a1a promoter, whereas mutating SBE1 or SBE2 restored cyp19a1a promoter activity. Co-overexpression of Smad4 and FoxH1 significantly reduced cyp19a1a promoter activity.

CONCLUSIONS

This study provides new insights into the potential functions of transcription factors Smad4 and FoxH1 in ovarian development and the transcriptional regulation mechanism of cyp19a1a in M. albus, which will reveal Smad4/FoxH1-mediated TGF-β signaling in reproduction and the regulation of the cyp19a1a. Aromatase, encoded by cyp19a1a, is involved in ovarian development and plays an important role in the quality of eggs, as well the sex ratio, of the teleost fish, M. albus. The research on the transcriptional regulation of cyp19a1a has contributed to the understanding of its role in ovarian development. In previous study, it was shown that FoxH1 inhibits cyp19a1a transcription. In the present study, Smad4 was confirmed as a cyp19a1a transcriptional repressor and Smad4 may also coordinate with FoxH1 to repress cyp19a1a transcription. At present, we provide a new perspective for the transcriptional regulation of cyp19a1a by transcription factors Smad4 and FoxH1 in teleost fish ovary. In the future, the regulatory networks of Smad4 and FoxH1 will be further studied and the gene editing technology will be applied to screen specific regulatory factors of cyp191a1a gene, so as to alter the female cycle and modulate the sex ratio of the eggs production.

miR-6881-3p contributes to diminished ovarian reserve by regulating granulosa cell apoptosis by targeting SMAD4

BACKGROUND

In our previous investigation, we revealed a significant increase in the expression of microRNA-6881-3p (miR-6881-3p) in follicular fluid granulosa cells (GCs) from women with diminished ovarian reserve (DOR) compared to those with normal ovarian reserve (NOR). However, the role of miR-6881-3p in the development of DOR remains poorly understood.

OBJECTIVE

This study aimed to elucidate the involvement of miR-6881-3p in the regulation of granulosa cells (GCs) function and the pathogenesis of DOR.

MATERIALS AND METHODS

Initially, we assessed the expression levels of miR-6881-3p in GCs obtained from human follicular fluid in both NOR and DOR cases and explored the correlation between miR-6881-3p expression and clinical outcomes in assisted reproduction technology (ART). Bioinformatic predictions and dual-luciferase reporter assays were employed to identify the target gene of miR-6881-3p. Manipulation of miR-6881-3p expression was achieved through the transfection of KGN cells with miR-6881-3p mimics, inhibitor, and miRNA negative control (NC). Following transfection, we assessed granulosa cell apoptosis and cell cycle progression via flow cytometry and quantified target gene expression through quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot (WB) analysis. Finally, we examined the correlation between target gene expression levels in GCs from NOR and DOR patients and their association with ART outcomes.

RESULTS

Our findings revealed elevated miR-6881-3p levels in GCs from DOR patients, which negatively correlated with ovarian reserve function and ART outcomes. We identified a direct binding interaction between miR-6881-3p and the 3'-untranslated region of the SMAD4. Transfection with miR-6881-3p mimics induced apoptosis in KGN cell. Furthermore, miR-6881-3p expression negatively correlated with both mRNA and protein levels of the SMAD4. The mRNA and protein levels of SMAD4 were notably reduced in GCs from DOR patients, and SMAD4 mRNA expression positively correlated with ART outcomes. In addition, the mRNA levels of FSHR, CYP11A1 were notably reduced after transfection with miR-6881-3p mimics in KGN cell, while LHCGR notably increased. The mRNA and protein levels of FSHR, CYP11A1 were notably reduced in GCs from DOR patients, while LHCGR notably increased.

CONCLUSION

This study underscores the role of miR-6881-3p in directly targeting SMAD4 mRNA, subsequently diminishing granulosa cell viability and promoting apoptosis, and may affect steroid hormone regulation and gonadotropin signal reception in GCs. These findings contribute to our understanding of the pathogenesis of DOR.

Characterization analysis of Rongchang pig population based on the Zhongxin-1 Porcine Breeding Array PLUS

OBJECTIVE

To carry out a comprehensive production planning of the existing Rongchang pig population from both environmental and genetic aspects, and to establish a closed population with stable genetic diversity and strict pathogen control, it is necessary to fully understand the genetic background of the population.

METHODS

We genotyped 54 specific pathogen free (SPF) Rongchang pigs using the Zhongxin-1 Porcine Breeding Array PLUS, calculated their genetic diversity parameters and constructed their families. In addition, we also counted the runs of homozygosity (ROH) of each individual and calculated the value of inbreeding coefficient based on ROH for each individual.

RESULTS

Firstly, the results of genetic diversity analysis showed that the effective population size (Ne) of this population was 3.2, proportion of polymorphic markers (PN) was 0.515, desired heterozygosity (He) and observed heterozygosity (Ho) were 0.315 and 0.335. Ho was higher than He, indicating that the heterozygosity of all the selected loci was high. Secondly, combining the results of genomic relatedness analysis and cluster analysis, it was found that the existing Rongchang pig population could be divided into four families. Finally, we also counted the ROH of each individual and calculated the inbreeding coefficient value accordingly, whose mean value was 0.09.

CONCLUSION

Due to the limitation of population size and other factors, the genetic diversity of this Rongchang pig population is low. The results of this study can provide basic data to support the development of Rongchang pig breeding program, the establishment of SPF Rongchang pig closed herd and its experimental utilization.