Abstract
Gene loci of highly expressed genes provide ideal sites for transgene expression. Casein genes are highly expressed in mammals leading to the synthesis of substantial amounts of casein proteins in milk. We have assessed the α-casein (CSN1S1) gene as a site of transgene expression in transgenic mice and a mammary gland cell line. A transgene encoding an antibody light chain gene (A1L) was inserted into the α-casein gene using sequential homologous and site-specific recombination. Expression of the inserted transgene is directed by the α-casein promoter, is responsive to lactogenic hormone activation, leads to the synthesis of a chimeric α-casein/A1L transgene mRNA and secretion of the recombinant A1L protein into milk. Transgene expression is highly consistent in all transgenic lines, but lower than that of the α-casein gene (4%). Recombinant A1L protein accounted for 0.5% and 1.6% of total milk protein in heterozygous and homozygous transgenic mice, respectively. The absence of the α-casein protein in homozygous A1L transgenic mice leads to a reduction of total milk protein and delayed growth of the pups nursed by these mice. Overall, the data demonstrate that the insertion of a transgene into a highly expressed endogenous gene is insufficient to guarantee its abundant expression. This article is protected by copyright. All rights reserved.
Original language | English |
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Article number | e2300287 |
Number of pages | 11 |
Journal | Biotechnology Journal |
Volume | 19 |
Issue number | 2 |
Early online date | 4 Dec 2023 |
DOIs | |
Publication status | Published - 1 Jan 2024 |
Bibliographical note
Open Access via the Wiley agreementACKNOWLEDGMENTS
This work was supported by grants from the BBSRC (Gene Technologies Underpinning Healthcare: #12599, CASE studentship BB/J012343/1), the Scottish Government (RESAS transition funding to A. Kolb), and the Genomia Trust Fund (protein expression in protein poor milk).
Data Availability Statement
Data available in article supplementary material.Keywords
- cellular engineering
- expression systems
- genomic engineering
- trangenic animals