Promoter-Specific Expression of the Imprinted IGF2 Gene in Cattle (Bos taurus)1

Abstract

The domestic cattle (Bos taurus) has been a good animal model for embryo biotechnologies, such as in vitro fertilization and nuclear transfer. However, animals produced from these technologies often suffer from large-calf syndrome, suggesting fetal growth disregulation. The product of the insulin-like growth factor 2 (IGF2) gene is one of the most important fetal mitogens known to date. A detailed analysis of age-, tissue-, and allele-specific expression of IGF2 has not been performed in the bovine mainly because the majority of the bovine sequence has been unavailable. In the present study, we obtained virtually the entire sequence of the bovine IGF2 cDNA, identified expressed single-nucleotide polymorphisms (SNPs) in both exons 3 and 10, and determined the age-, tissue-, and promoter-specific expression of bovine IGF2 in fetal, calf, and adult tissues. We found that, similar to the human and mouse, bovine IGF2 is subjected to extensive transcriptional regulation through multiple promoters, alternative splicing and polyadenylation, as well as genetic imprinting. However, major differences were found in the regulation of the bovine IGF2 in nearly all aspects of age-, tissue-, promoter-, and allele-specific expression of IGF2, and the promoter-specific loss of imprinting from every other species studied, including cattle's close relatives, the sheep and the pig. The data presented here are of important reference value to cattle produced from embryo biotechnologies.

An association of C/T polymorphism in exon 2 of the bovine insulin-like growth factor 2 gene with meat production traits in Polish Holstein-Friesian cattle

“…In the liver of a male foetus from 2-month gestation the paternal allele was primarily expressed, as shown by both cDNA sequencing and PCR-RFLP. Therefore, in agreement with the previously reported data (Curchoe et al, 2005), our results showed that in bovine liver the paternal allele-specific expression of the IGF2 gene occurred only in early stages of development, i.e. in foetuses up to two months of gestation.…”

“…Total RNA was isolated from livers of heterozygous CT bulls, reverse transcribed to cDNA, and PCR amplified using primers matching exon 2, with the polymorphic g.292C>T site. These primers allowed the identification of liver-specific IGF2 mRNA, transcribed from IGF2 promoter 1 (bovine IGF2 gene has four alternative promoters -P1, P2, P3, and P4; Curchoe et al, 2005). Previously, while studying the IGF2 gene expression in different organs/tissues of adult, 15-months-old HF bulls by real-time PCR we found a relatively high content of IGF2 mRNA in kidney, liver and testis, but only trace amounts in bovine muscles (longissimus dorsi and semitendinosus) (Lisowski and Zwierzchowski, unpublished).…”

“…In cattle, the preferential paternal expression of the IGF2 gene was reported first by Dindot et al (2004). Curchoe et al (2005) showed a promoter-specific loss of imprinting of the IGF2 gene in cattle after birth. The imprinting of growth factor genes may influence the foetal growth and growth after birth.…”

Genetic polymorphisms of the IGF-II gene intron 8 coding region and its association with growth and carcass traits in yak

“…Preferential paternal expression of the IGF-II gene was first reported by Dindot et al (2004). In addition, Curchoe et al (2005) showed a promoter-specific loss of imprinting of the IGF-II gene in cattle after birth.…”

“…Curchoe et al (2005) identified an SNP in exon 3 and an SNP after the stop codon of exon 10, and an indel in IGF-II of Bos taurus was reported by Flisikowski et al (2006). A C/T transition (RFLP-BsrI) at position 292 was first reported by Goodall and Schmutz (2003).…”