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Published on: July 22, 2025
Mutation of murine Sox4 untranslated regions results in partially penetrant perinatal lethality
Walter Guy Wiles1, Zhongming Mou2, Yang Du3
1Winship Cancer Institute, Emory University School of Medicine, Atlanta, GA, U.S.A.
Background:
Sox4 is an essential gene, and genetic deletion results in embryonic lethality. In an effort to develop mice with tissue-specific deletion, we bred conditional knockout mice bearing LoxP recombination sites flanking the Sox4 gene, with the LoxP sites located in the Sox4 5'UTR and 3'UTR.
Results:
The number of mice homozygous for this LoxP-flanked conditional knockout allele was far below the expected number, suggesting embryonic lethality with reduced penetrance. From over 200 animals bred, only 11% were homozygous Sox4(flox/flox) mice, compared to the expected Mendelian ratio of 25% (p<0.001). Moreover, there was a significant reduction in the number of female Sox4(flox/flox) mice (26%) relative to male Sox4(flox/flox) mice (p=0.0371). Reduced Sox4 expression in homozygous embryos was confirmed by in-situ hybridization and Quantitative real-time polymerase chain reaction (QPCR).
Conclusion:
LoxP sites in the 5' and 3' UTR of both alleles of Sox4 resulted in reduced, but variable expression of Sox4 message.
Insights
Conditional knockout mice with LoxP sites flanking the Sox4 gene showed reduced penetrance, leading to embryonic lethality. Sox4 gene expression was variable in homozygous mice.
Area of Science:
- Developmental biology
- Genetics
- Molecular biology
Background:
- Sox4 is a crucial gene, with complete genetic deletion causing embryonic lethality.
- Conditional knockout mice were generated to study tissue-specific Sox4 deletion.
- LoxP recombination sites were strategically placed in the 5'UTR and 3'UTR of the Sox4 gene.
Purpose of the Study:
- To investigate the effects of flanking the Sox4 gene with LoxP sites.
- To develop a conditional knockout mouse model for Sox4.
- To assess the viability and gene expression in mice with modified Sox4 alleles.
Main Methods:
- Breeding of conditional knockout mice with LoxP sites flanking the Sox4 gene.
- Genotyping to determine the Mendelian ratio of homozygous Sox4(flox/flox) mice.
- In-situ hybridization and Quantitative real-time polymerase chain reaction (QPCR) to assess Sox4 expression.
Main Results:
- Significantly fewer homozygous Sox4(flox/flox) mice were observed than expected (11% vs. 25%, p<0.001), indicating reduced penetrance and embryonic lethality.
- A notable reduction in female Sox4(flox/flox) mice compared to males was observed (p=0.0371).
- Reduced Sox4 expression in homozygous embryos was confirmed through in-situ hybridization and QPCR.
Conclusions:
- Placing LoxP sites in the 5' and 3' UTR of Sox4 alleles resulted in reduced, but variable, Sox4 message expression.
- The genetic manipulation led to embryonic lethality with incomplete penetrance.
- The study highlights the critical role of Sox4 during embryonic development.
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