Association of IL-4 and IL-4R Polymorphisms with Litter Size Traits in Pigs.

Watcharapong Naraballobh,Siriwadee Chomdej,Korakot Nganvongpanit,Tawatchai Teltathum,Trisadee Khamlor,Supamit Mekchay,Pantaporn Supakankul,Patcharin Krutmuang,Korawan Sringarm,Guisheng Liu,Worrarak Norseeda

doi:10.3390/ani11041154

Abstract

Simple SummaryThe IL-4 and IL-4R cytokine genes are responsible for immune response in the reproductive system and are related to embryonic implantation and fetal survival during pregnancy in females. However, to date, their effects on litter size traits in pigs have been not elucidated. Therefore, the present study was conducted to verify the porcine IL-4 and IL-4R polymorphisms and assess how they affect litter size traits in commercial pigs. The findings suggested that the porcine IL-4 g.134993898T > C and IL-4R c.1577A > T polymorphisms were associated with the litter size traits. Therefore, the porcine IL-4 and IL-4R genes may be potentially effective genetic markers to improve the litter size traits in pigs.The interleukin-4 (IL-4) and interleukin-4 receptor (IL-4R) are cytokines that are involved in the immune and reproductive systems. This study aimed to verify the polymorphisms in the porcine IL-4 and IL-4R genes and to assess their effects on litter size traits in commercial pigs. Single nucleotide polymorphisms (SNPs) in the porcine IL-4 and IL-4R genes were genotyped by the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. A non-coding SNP of IL-4 g.134993898T > C and a non-synonymous SNP of IL-4R c.1577A > T (amino acid change at position 526, Q526L) were found to be segregating in Landrace sows. The IL-4 g.134993898T > C polymorphism was significantly associated with the number of piglets weaned alive (NWA) trait. The IL-4R c.1577A > T polymorphism was significantly associated with the number born alive (NBA) and NWA traits. Moreover, the accumulation of favorable alleles of these two SNP markers revealed significant associations with the NBA, NWA, and mean weight of piglets at weaning (MWW) traits. These findings indicate that the porcine IL-4 and IL-4R genes may contribute to the reproductive traits of pigs and could be used as candidate genes to improve litter size traits in the pig breeding industry.

Highlights

Litter size traits are among the most important traits for breeding in commercial pig production
Numerous studies have demonstrated the role of different cytokines in the channel of communication established between the trophoblast and maternal endometrium, which contributes to embryo implantation and the pregnancy of pigs [8,40,41]
The results in this study indicate that the porcine IL-4 and interleukin-4 receptor (IL-4R) genes could be expected to be involved in the reproductive processes of pigs, especially with regard to litter size traits

Summary

Introduction

Litter size traits are among the most important traits for breeding in commercial pig production. Increasing litter size is of great economic interest as a means of enhancing the productivity of the pig industry [1,2,3]. Communication between the conceptus and the endometrium is mediated by cytokines and cell surface receptors [6], and it is essential for embryo implantation, placental development, and the effective maintenance of pregnancy [7,8]. Several cytokine genes involved in embryo attachment and implantation that affect the relevant litter size traits have been identified in pigs, e.g., erythropoietin-producing hepatocellular A4 (EphA4) [5], ring finger protein 4 gene (RNF4) [9], leukemia inhibitory factory (LIF) [10], interleukin-6 (IL-6) [11], and osteopontin (OPN) [12].

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