Secretion of a recombinant protein without a signal peptide by the exocrine glands of transgenic rabbits

Abstract

Transgenic rabbits carrying mammary gland specific gene constructs are extensively used for excreting recombinant proteins into the milk. Here, we report refined phenotyping of previously generated Venus transposon-carrying transgenic rabbits with particular emphasis on the secretion of the reporter protein by exocrine glands, such as mammary, salivary, tear and seminal glands. The Sleeping Beauty (SB) transposon transgenic construct contains the Venus fluorophore cDNA, but without a signal peptide for the secretory pathway, driven by the ubiquitous CAGGS (CAG) promoter. Despite the absence of a signal peptide, the fluorophore protein was readily detected in milk, tear, saliva and seminal fluids. The expression pattern was verified by Western blot analysis. Mammary gland epithelial cells of SB-CAG-Venus transgenic lactating does also showed Venus-specific expression by tissue histology and fluorescence microscopy. In summary, the SB-CAG-Venus transgenic rabbits secrete the recombinant protein by different glands. This finding has relevance not only for the understanding of the biological function of exocrine glands, but also for the design of constructs for expression of recombinant proteins in dairy animals.

Long-term health and germline transmission in transgenic cattle following transposon-mediated gene transfer

“…This report also demonstrates that transgenic cattle can act as potential bioreactors for the secretion of exogenous proteins in milk [ 39 – 41 ], as we identified the production of YFP in milk from SNU-SB-1 (Additional file 3 : Figure S2). Further, SNU-F1–1 was fed the YFP-containing milk from SNU-SB-1 for 7 months until weaning.…”

Electroporation-based Easi-CRISPR yields biallelic insertions of EGFP-HiBiT cassette in immortalized chicken oviduct epithelial cells

“…It was produced in the milk of transgenic goats ( Kling, 2009 ). Later, mammal breast gland bioreactors were generated from rabbit ( Kerekes et al, 2017 ), mice ( Zeng et al, 2017 ), goat ( Carneiro et al, 2018 ), and pig ( Lee et al, 2020 ). However, various difficulties such as long timelines for reproduction and generation interval, complex biochemical composition of milk proteins, and difficult purification of recombinant proteins are associated with these bioreactors.…”