Gq. Yang et al., CLONING OF 5'-REGULATORY ELEMENT OF BOVINE BETA-LACTOGLOBULIN GENE AND ITS UTILIZATION IN GENERATION OF MAMMARY BIOREACTORS, SCIENCE IN CHINA SERIES C-LIFE SCIENCES, 39(6), 1996, pp. 662-669
To obtain a regulatory element for generating mammary bioreactors, a D
NA fragment derived from bovine beta-lactoglobulin (BLG) gene was clon
ed, which consisted of a 650-bp 5' flanking sequence, exon I, intron I
and exon II. A 661-bp region of the cloned fragment, consisting Of th
e 650-bp 5' flanking sequence and a non-coding sequence of 11 bp downs
tream of the transcription initiation site, was used as a regulatory e
lement to combine with human growth hormone (hGH) gene to generate a b
ovine BLG/hGH fusion construct, which was then introduced into culture
d primary mammary epithelial cells of goat for transient expression of
hGH gene. It was demonstrated that the hGH gene was able to express f
ollowing hormone induction and the expressed product was able to be se
creted into the medium. The bovine BLG/hGH fusion construct was also u
sed to generate transgenic mice by microinjection. Subsequently, five
transgenic mice were generated. The hGH in milk by one transgenic fema
le mouse was 420 mu g/mL, while the content of hGH in serum was 0.051
mu g/mL only. This indicated that the cloned regulatory element in thi
s experiment could make the expression of target gene occur almost spe
cifically in mammary gland and the expressed product could be secreted
with milk.