Isolation of the bovine CYP19 promoter 1.2 and identification of genetic variants

Variants in the CYP19A1 gene can affect in vitro embryo production traits in cattle

PURPOSE

This study aimed to associate DNA variants in promoter and exon flanking regions of the CYP19A1 gene with in vitro embryo production traits in cattle. The role of transcription factor binding sites created or lost due to DNA sequence variation and their possible effect on gene expression was also evaluated.

METHODS

We collected date from Gyr dairy oocyte donor cows (Bos taurus indicus) at a commercial in vitro embryo production farm and analyzed the genotype-phenotype association with in vitro production traits. Using Sanger sequencing and web-based software, we assessed important CYP19A1 gene regions in oocyte donor cows and analyzed the effects of variants on the transcription factor binding sites.

RESULTS

Two SNP mutations significantly associated with oocyte production, oocyte viability, embryo development, and pregnancies were found (T > C in the untranslated exon 1 flanking region ([GenBank: AJ250379.1]: rs718446508 T > C), and a T > C in the 5'-upstream region (1.1 promoter) ([GenBank: AC_000167.1]: rs41651668 T > C). Six new transcription factor binding sites were created. A binding site for transcription factors associated with the development of the placenta and embryo implantation was eliminated due to variations in the DNA sequence identified.

CONCLUSIONS

The CYP19A1 gene contributes to genetic variation of in vitro embryo production traits in cattle. The complexity of the physiological phenomena related to estrogen pathways and their influence on reproduction in cattle allow indication of the mutations evaluated here as possible genetic markers for embryo production traits, which should be validated in the next steps of marker-assisted selection.

Expression of the aromatase cytochrome P450 encoding gene in cattle and sheep

During this report the tissue-specific expression and promoter usage of the aromatase cytochrome P450 encoding gene, Cyp19, are compared between cattle and sheep. In addition, data will be presented on the identification of cis-acting regulatory sequences located in the bovine placenta-specific promoter 1.1. In cattle and sheep Cyp19 is mainly expressed in the foetal placental layer and ovarian granulosa cells but also in other organs as brain or testis. Differently spliced transcripts of Cyp19 which include an invariable coding region but a variable 5'-untranslated region could be detected in tissues of both species. However, in contrast to ovary and brain which express homologous transcript variants, different transcripts are present in placentae suggesting that also different placenta-specific promoter regions are active in cattle and sheep. The analysis of the chromatin structure of the main placental promoter 1.1 in different bovine tissues revealed that hypomethylation and the occurrence of DNaseI hypersensitive sites (HS) within this region are associated with promoter activity. Active regulatory elements were identified in reporter gene studies in JEG-3 choriocarcinoma cells. The co-localisation of an E-box element within one of the placenta-specific HS suggests that this element is important for Cyp19 expression in the bovine placenta.