Expression of antisense of insulin-like growth factor-2 receptor RNA non-coding (AIRN) during early gestation in cattle

Abstract

The insulin-like growth factor type 2 receptor (IGF2R) regulates fetal growth by removing IGF2 from circulation. In mice, expression of the Igf2r gene is only imprinted after implantation and is associated with expression of the antisense non-coding (nc)RNA, Airn. The objectives of this study were, first, to determine if bovine AIRN was expressed during developmentally important stages of gestation, and second, to determine if expression of bAIRN was affected by method of embryo production. Control reactions confirmed that sequence verified bAIRN PCR amplicons resulted from RNA within the sample and not from genomic DNA contamination. IGF2R mRNA was expressed in all fetal liver samples at Days 35–55 and 70 of gestation as well as in 8 of 9 Day 15 conceptuses, 10 of 10 Day 18 conceptuses, and in all day 7 blastocyst pools. bAIRN was expressed in all samples of fetal liver at Days 35–55 and 70 of gestation. The proportion of conceptuses that expressed bAIRN increased from 1 of 9 at Day 15 of gestation to 8 of 10 at Day 18 of gestation. No bAIRN was expressed in any blastocyst pools. The relative level of bAIRN was greater (P<0.05) in fetal liver from embryos produced in vivo compared to that from embryos produced in vitro. In summary bAIRN was not expressed in blastocyst-stage embryos, was expressed in an increasing proportion of embryos around the time of maternal recognition of pregnancy and was expressed following implantation. Furthermore, relative levels of bAIRN in bovine fetal liver can be altered by method of embryo production.