Cloning, transcription and chromosomal localization of the porcine whey acidic protein gene and its expression in HC11 cell line

The whey acidic protein (WAP) is the major whey protein of rodent, rabbit a nd camel. Recently, it was identified in the milk of swine (Simpson et al., 1998. J. Mol. Endocrinol. 20, 27-35). In this paper, the cloning of the pi g WAP cDNA and of bacterial artificial chromosome (BAC) construct containin g the entire porcine WAP gene is reported. The comparison of the coding seq uence of the pig WAP gene to rodent or lagomorph WAP sequence already publi shed demonstrated that only exon sequences are partially conserved. The por cine WAP gene was localized on the subtelomeric region of the chromosome 18 . The estimation of the expression of the swine WAP gene in the mammary gla nd from lactating animals revealed a high level of expression. In order to compare the expression level of the porcine WAP gene from the large genomic fragment which contained 70 kb downstream and 50 kb upstream the pig WAP g ene or the smaller one (1 kb downstream and 2.4 kb upstream), these two gen omic fragments were transfected in HC11 cell line. The BAC construct was ex pressed 15 times higher than the plasmid when reported to the integrated co py number. This report suggests that the HC11 cell line is a useful tool to identify the regulatory sequences of milk protein genes. (C) 2001 Elsevier Science B.V. All rights reserved.