|GU, T - Huazhong Agricultural University
|ZHU, MJ - Huazhong Agricultural University
|SCHROYEN, M - Iowa State University
|QU, L - Iowa State University
|NETTLETON, D - Iowa State University
|ZHAO, SH - Huazhong Agricultural University
|TUGGLE, C - Iowa State University
Submitted to: BMC Genomics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/17/2014
Publication Date: 2/24/2014
Citation: Gu, T., Zhu, M., Schroyen, M., Qu, L., Nettleton, D., Kuhar, D.J., Lunney, J.K., Zhao, S., Tuggle, C. 2014. Endometrial gene expression profiling in pregnant Meishan and Yorkshire breeds at peri-implantation to characterize the prolific nature of pigs. Biomed Central (BMC) Genomics. 15:156.
Interpretive Summary: Selecting pigs for better production traits, e.g., for larger litter size, is a major factor for improving profitability. Previous studies revealed considerable influence of the maternal uterine endometrium, and the closely related trait early embryo mortality, in determining litter size. In this manuscript we probed gene expression and associated gene regulation networks in the sow's uterine endometrium. We compared tissues from two breeds, the prolific Chinese Meishan with the Yorkshire, breeds for which studies had affirmed very different rates of embryo survival. We characterized the earliest stages of embryo development, the peri-implantation stage in uterine endometrial tissues. We predicted that this gene expression profile would be correlated with the prolific nature of pigs. We used the porcine Affymetrix GeneChip to assay the gene expression profiles in the uterine endometrium tissues obtained from Meishan (high embryo survival) and Yorkshire (low embryo survival) gilts at day 12 of gestation. Statistical analysis predicted a total of 2,656 transcripts as differentially expressed between Meishan and Yorkshire pig samples. Gene functions were involved in important biological processes such as blood vessel development, transcription regulation, tight junction, and inflammatory response. Overall our results revealed unique endometrial gene expression profiles in two breeds differing in embryonic survival. They identified candidate genes that may provide new clues to understand the prolific nature of pigs and important reproductive pathways.
Technical Abstract: Background: The prolificacy trait of pigs (larger litter size) is a major factor affecting the profitability in the pig industry. Previous studies revealed that the function of the maternal uterine endometrium, which has been shown to be closely related to early embryo mortality, has considerable influence in determining litter size. However, the gene expression and regulation networks in the endometrium underlying prolificacy remain poorly understood. Results: We characterized the peri-implantation stage endometrial gene expression profile that is potentially associated with the prolific nature of pigs by comparing two breeds (Meishan and Yorkshire) with very different rates of embryo survival. We employed the porcine Affymetrix GeneChip to assay the transcriptomic profiles of genes expressed in the uterine endometrium tissues obtained from Meishan (high embryo survival) and Yorkshire (low embryo survival) gilts (n=4 for each breed) at day 12 of gestation (M12 and Y12, respectively). More than 15,293 probesets (transcripts) were identified as "present" in at least two arrays. A mixed model-based statistical analysis predicted a total of 2,656 (q<0.1) transcripts as differentially expressed between Meishan and Yorkshire pigs. Eighteen differentially expressed genes of interest were validated by quantitative real-time PCR. Gene ontology (GO) annotation revealed that the known functions of the differentially expressed genes were involved in a series of important biological processes such as blood vessel development, transcription regulation, tight junction, and inflammatory response. Conclusions: The results revealed unique endometrial gene expression profiles in two breeds differing in embryonic survival and identified candidate genes that are related to known physiological pathways related to sow prolificacy. Our findings therefore provide new clues to understand the prolific nature of pigs and reproductive pathways differing between these two breeds at the critical peri-implantation stage of pregnancy.