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Retrotransposon-mediated Fgf5(go-Utr) mutant mice with long pelage hair
Seiya Mizuno1, Saori Iijima, Tomoko Okano
1Laboratory Animal Resource Center, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575, Japan.
Abstract:
We found 6 spontaneous mutant mice with long pelage hair in our ICR breeding colony. The abnormal trait was restricted to long hair in these mice, which we named moja. They were fertile and showed the same growth and behavior as wild-type mice. To investigate the manner of the genetic inheritance of the moja allele, offspring were bred by mating the moja mice; all offspring had long pelage hair. Furthermore, we performed a reciprocal cross between moja mice and wild-type ICR mice with normal hair. All offspring exhibited normal hair suggesting an autosomal recessive inheritance of the trait. The moja/moja hair phenotype was maintained in skin grafted onto nude mice, suggesting that circulating or diffusible humoral factors regulating the hair cycle are not involved in the abnormal trait. The phenotype of moja/moja mice is similar to that of Fgf5-deficient mice. Therefore, we examined the expression of Fgf5 by RT-PCR in moja/moja mice. As expected, no Fgf5 expression was found in moja/moja mouse skin. PCR and DNA sequence analyses were performed to investigate the structure of the Fgf5 gene. We found a deletion of a 9.3-kb region in the Fgf5 gene including exon 3 and its 5' and 3' flanking sequences. Interestingly, the genomic deletion site showed insertion of a 498-bp early transposon element long terminal repeat. Taken together, these results suggest that the long hair mutation of moja/moja mice is caused by disruption of Fgf5 mediated by insertion of a retrotransposon.
Insights
A spontaneous mutation in mice, named moja, causes long pelage hair due to a genetic defect. This autosomal recessive trait results from a deletion in the Fgf5 gene, linked to retrotransposon insertion.
Area of Science:
- Genetics
- Developmental Biology
- Molecular Biology
Background:
- Spontaneous mutations provide valuable insights into gene function.
- The Fgf5 gene is known to play a crucial role in hair growth regulation.
Purpose of the Study:
- To characterize a novel spontaneous mutation in mice exhibiting long pelage hair.
- To elucidate the genetic basis and molecular mechanism underlying the 'moja' hair phenotype.
Main Methods:
- Genetic crosses (intercrosses and reciprocal crosses) to determine inheritance patterns.
- Skin grafting onto nude mice to assess the role of humoral factors.
- RT-PCR and DNA sequencing to analyze Fgf5 gene expression and structure.
Main Results:
- The 'moja' trait is inherited in an autosomal recessive manner.
- The mutation is intrinsic to the skin, independent of circulating factors.
- Moja mice exhibit a complete lack of Fgf5 expression.
- A large deletion within the Fgf5 gene, including exon 3 and flanking regions, was identified.
- The deletion site contained an inserted retrotransposon element.
Conclusions:
- The 'moja' mutation is caused by a disruption of the Fgf5 gene.
- Retrotransposon insertion leading to Fgf5 gene deletion is the molecular mechanism for the long hair phenotype.
- This finding highlights the role of Fgf5 in regulating hair length and the impact of transposon activity in mammalian genetics.
