Identification of Cis-regulatory Elements of Butyrophilin Gene of the Mammary Gland

Abstract

Butyrophilin subfamily 1 member A1 is a highly expressed gene in  mammary gland of all mammals during lactation. It is found to be the major integral protein in the milk fat globule membrane. Its interactions with other membrane elements and soluble proteins of the mammary  epithelial cells regulate the secretion of milk fat. In order to reveal any shared cis-acting elements, the human butyrophilin subfamily 1member A1 5’-flanking genomic sequence was analyzed and compared with four mammals comprising of a rodent and three primates, viz., Mus musculus, and Pan troglodytes, Pongo obelli, and Macaca mulata, and three other mammary specific human milk genes using publicly available  bioinformatics tools. Prior to a multiple sequence analysis, low complexity
DNA sequences were masked using CENSOR. The multiple sequence  analysis revealed nine highly conserved regions of similarities in the 5’- flanking region of butyrophilin genes across species. Consensus putative transcription factor binding sites were identified using MatInspector and compared with SiteGA results. They were subsequently examined for the expression in the mammary gland as well as for their occurrence in the previously identified region of homology. Finally, CCCTCbinding factor (CTCF) and nuclear receptor subfamily 2 - factor (NR2F) were identified
at a similar distance from the transcription start site in the 5’- flanking region of butyrophilin gene across the species. However, the exact  interaction of these transcription factors with the butyrophilin gene is not known, which needs further investigation.