The collagen type I alpha 1 chain gene is an alternative safe harbor locus in the porcine genome

• Published in: Journal of Integrative Agriculture 2023-01, Vol.22 (1), p.202-213
• Main Authors: XIANG, Guang-ming, ZHANG, Xiu-ling, XU, Chang-jiang, FAN, Zi-yao, XU, Kui, WANG, Nan, WANG, Yue, CHE, Jing-jing, XU, Song-song, MU, Yu-lian, LI, Kui, LIU, Zhi-guo
• Format: Article
• Language: English
• Subjects: COL1A1 gene; CRISPR/Cas9; knock-in; pig; safe harbor
• ISSN: 2095-3119; 2352-3425
• DOI: 10.1016/j.jia.2022.08.105

Efficient and stable expression of foreign genes in cells and transgenic animals is important for gain-of-function studies and the establishment of bioreactors. Safe harbor loci in the animal genome enable consistent overexpression of foreign genes, without side effects. However, relatively few safe harbor loci are available in pigs, a fact which has impeded the development of multi-transgenic pig research. We report a strategy for efficient transgene knock-in in the endogenous collagen type I alpha 1 chain (COL1A1) gene using the clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 9 (CRISPR/Cas9) system. After the knock-in of a 2A peptide-green fluorescence protein (2A-GFP) transgene in the last codon of COL1A1 in multiple porcine cells, including porcine kidney epithelial (PK15), porcine embryonic fibroblast (PEF) and porcine intestinal epithelial (IPI-2I) cells, quantitative PCR (qPCR), Western blotting, RNA-seq and CCK8 assay were performed to assess the safety of COL1A1 locus. The qPCR results showed that the GFP knock-in had no effect (P=0.29, P=0.66 and P=0.20 for PK15, PEF and IPI-2I cells, respectively) on the mRNA expression of COL1A1 gene. Similarly, no significant differences (P=0.64, P=0.48 and P=0.80 for PK15, PEF and IPI-2I cells, respectively) were found between the GFP knock-in and wild type cells by Western blotting. RNA-seq results revealed that the transcriptome of GFP knock-in PEF cells had a significant positive correlation (P