Association of P-selectin Gene SNPs and Haplotypes with Abortion Risk in Cattle

Abstract

Selectin plays a crucial role in the form of a key molecular mediators for feto-maternal communication during pregnancy. Particularly, P-selectin is an adhesion molecule expressed predominantly on activated endothelial cells and platelets is also widely recognized for its role in leukocyte recruitment during inflammation, its importance in maintaining gestational homeostasis, promoting immune cell trafficking, and ensuring successful placental vascular development in ruminants such as cattle. The polymorphism in selectin genes could lead to abortion through changes in initial adhesion between conceptus and mother and/or by altering the later influx of inflammatory cells into the placenta. Therefore, this study was conducted on 141 Karan Fries (Bos taurus x Bos indicus) cows maintained at ICAR-National Dairy Research Institute, Karnal to find out the association between P- selectin gene polymorphisms with susceptibility to abortion. A total of five SNPs viz., rs42312260 (exon 5), rs137027551 (exon 6), rs211448260 (exon 6), rs378218397 (exon 8), rs211179622 (3' UTR) were genotyped by PCR-RFLP using the restriction enzymes BstBI, Hpy188I, SmaI, NdeI and PstI, respectively. Alignment with reference protein sequence revealed that rs42312260, rs211448260 and rs378218397 were of non-synonymous type leading to amino acid substitutions from Glutamic acid to alanine, arginine to glutamine and valine to methionine, respectively. The logistic regression analysis was carried out to find out the effect of genotypes of each SNPs on the incidence of abortion in Karan Fries cows. The SNPs rs378218397 and rs137027551 were found to be significantly associated with abortion. The GA genotype animals for rs378218397 had 2.045 fold higher odds of abortion than GG genotype animals. But no AA genotype was found in this study which suggests that AA homozygous fetus might have died during pregnancy. The genotypes of SNP rs137027551 gene had significant association with the risk of abortion. For SNP rs137027551, there was a linear increase in probability of abortion from AA to AG to GG. The AG and GG genotypes had 3.33 and 5.18 times greater risk of abortion than AA genotype animals, respectively. The SNP rs211448260, rs137027551 and rs42312260 were in linkage disequilibrium (LD) and formed a haplotype block. The case control association study showed that among the eight Selectin haplotypes constructed, GGC haplotype occurred at a higher frequency in abortion cases, whereas the GAA haplotype occurred at a lower frequency. These results suggest that the GGC haplotype may be associated with increased susceptibility to abortion, while the GAA haplotype may be associated with reduced susceptibility to abortion in Karan Fries cows. These genetic variants and associated haplotypes may serve as potential genetic markers for susceptibility to abortion after validation in larger populations.