title: Identification of Differentially Expressed Genes Associated with Litter Size in Berkshire Pig Placenta.
abstract: Improvement in litter size has become of great interest in the pig industry because fecundity is directly related to sow reproductive life. Improved reproduction has thus been achieved by elucidating the molecular functions of genes associated with fecundity. In the present study, we identified differentially expressed genes (DEGs) via transcriptomic analysis using RNA-sequencing (RNA-Seq) in Berkshire pig placentas from larger (LLG, mean litter size >12) and smaller (SLG, mean litter size < 6.5) litter size groups. In total 588 DEGs were identified (p < 0.05, > 1.5-fold change), of which 98 were upregulated, while 490 were downregulated in the LLG compared with the SLG. Gene Ontology (GO) enrichment was also performed. We concluded that 129 of the 588 DEGs were closely related to litter size according to reproduction related genes selected based on previous reports, as 110 genes were downregulated and 19 upregulated in the LLG compared with the SLG. RT-qPCR utilizing specific primers targeting the early growth response 2 (EGR2), pheromaxein c subunit (PHEROC) and endothelial lipase (LIPG) genes showed high accordance with RNA-Seq results. Furthermore, we investigated the upstream regulators of these three genes in the placenta. We found that WNT9B, a Wnt signaling pathway molecule, and IL-6, known inducers of EGR2 and LIPG, respectively, were significantly increased in LLG compared with SLG. We believe that the induction of IL-6 and LIPG may play an important role in increasing nutrition supply through the placenta from the sow to the piglet during gestation. These results provide novel molecular insights into pig reproduction.
authors.affiliation: Swine Science and Technology Center, Gyeongnam National University of Science & Technology, Jinju, South Korea.
authors.forename: Seul Gi
authors.initials: SG
authors.lastname: Kwon
authors.affiliation: Swine Science and Technology Center, Gyeongnam National University of Science & Technology, Jinju, South Korea.
authors.forename: Jung Hye
authors.initials: JH
authors.lastname: Hwang
authors.affiliation: Swine Science and Technology Center, Gyeongnam National University of Science & Technology, Jinju, South Korea.
authors.forename: Da Hye
authors.initials: DH
authors.lastname: Park
authors.affiliation: Swine Science and Technology Center, Gyeongnam National University of Science & Technology, Jinju, South Korea.
authors.forename: Tae Wan
authors.initials: TW
authors.lastname: Kim
authors.affiliation: Swine Science and Technology Center, Gyeongnam National University of Science & Technology, Jinju, South Korea.
authors.forename: Deok Gyeong
authors.initials: DG
authors.lastname: Kang
authors.affiliation: Swine Science and Technology Center, Gyeongnam National University of Science & Technology, Jinju, South Korea.
authors.forename: Kyung Hee
authors.initials: KH
authors.lastname: Kang
authors.affiliation: Department of Animal Resource Technology, Gyeongnam National University of Science & Technology, Jinju, South Korea.
authors.forename: Il-Suk
authors.initials: IS
authors.lastname: Kim
authors.affiliation: Dasan Pig Breeding Co., Namwon, South Korea.
authors.forename: Hwa Chun
authors.initials: HC
authors.lastname: Park
authors.affiliation: Department of Animal Biotechnology, Chonbuk National University, Jeonju, South Korea.
authors.forename: Chong-Sam
authors.initials: CS
authors.lastname: Na
authors.affiliation: Swine Science and Technology Center, Gyeongnam National University of Science & Technology, Jinju, South Korea.
authors.forename: Jeongim
authors.initials: J
authors.lastname: Ha
authors.affiliation: Swine Science and Technology Center, Gyeongnam National University of Science & Technology, Jinju, South Korea.
authors.forename: Chul Wook
authors.initials: CW
authors.lastname: Kim
mesh_terms: D000818:Animals; D005260:Female; D020869:Gene Expression Profiling / Q000379:methods; D063990:Gene Ontology; D008098:Litter Size / Q000235:genetics*; D010920:Placenta / Q000378:metabolism*; D011247:Pregnancy; D012098:Reproduction / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017423:Sequence Analysis, RNA; D013552:Swine / Q000235:genetics*; D059467:Transcriptome