Journal of Dairy Research


Special Issue

Functional study of the equine β-casein and κ-casein gene promoters


Tina Lenasi a1, Nadja Kokalj-Vokac a2, Mojca Narat a1, Antonella Baldi a3 and Peter Dovc a1c1
a1 University of Ljubljana, Biotechnical faculty, Department of Animal Science, Groblje 3, SI-1230 Domzale, Slovenia
a2 Teaching Hospital Maribor, Ljubljanska 5, Maribor, SI-2000, Slovenia
a3 University of Milan, Veterinary Faculty, Institute of Animal Nutrition, Via Trentacoste 2, I-20134 Milan, Italy

Article author query
lenasi t   [PubMed][Google Scholar] 
kokalj-vokac n   [PubMed][Google Scholar] 
narat m   [PubMed][Google Scholar] 
baldi a   [PubMed][Google Scholar] 
dovc p   [PubMed][Google Scholar] 

Abstract

Casein genes are expressed in a tissue-specific and highly coordinated manner. The main goals of casein gene promoter studies are to unravel cis- and trans-acting factors involved in the complex signalling pathway controlling milk production, and to explore the possibility of using these promoters for tissue-specific production of heterologous proteins in the mammary gland. Here we present a comparative study of the equine β-casein and κ-casein gene proximal promoters. In order to confirm the assumption that in the horse, as in other mammalian species, casein genes are organized in a cluster located on a single chromosome, we performed in situ hybridization of pro-metaphase chromosomes with two BAC clones containing different equine casein genes. Sequence analysis of the β-casein and κ-casein gene proximal promoters revealed binding sites for activators (STAT5, GRE, NF1, MAF) and repressors (YY1, PMF), characteristic for casein genes. The alignments of casein gene promoters revealed the highest sequence identity in the proximal promoter region between the equine and human β-casein gene promoters. We directly compared the activity of equine β-casein and κ-casein gene promoters in vitro using bovine mammary gland cell line BME-UV1. In this system, the κ-casein gene proximal promoter activated the reporter gene expression more efficiently than the β-casein gene promoter of approximately the same length. The 810 bp of β-casein promoter activated the reporter gene expression more efficiently than the long fragment (1920 bp) and the 1206 bp fragment of the same promoter, which included also 396 bp of 5′ UTR.

(Published Online July 14 2005)


Key Words: Equine casein genes; FISH; BME-UV1 cells; ECA3; reporter gene; EMSA; proximal promoter region.

Correspondence:
c1 e-mail: peter.dovc@bfro.uni-lj.si