Background and Aims The Berlin Fat Mouse Inbred (BFMI) line carries natural mutations that can help understanding
genetic mechanisms causing obesity. The jObes1 locus on chromosome 3 in BFMI explains
~40% of the variance of body weight. The expression of the candidate gene Bbs7 is
reduced in brain, adipose tissue and liver. The goal was to identify potential regulatory
DNA variants.
Material and Methods To investigate the genetic effect on expression, we compared the effect of 16 DNA
sequence variants between BFMI and C57BL/6N (B6N) in the promoter region and a 1578
bp deletion in intron 8 of Bbs7. Various sequences of the Bbs7 promoter of BFMI and
B6N were cloned into dual-luciferase reporter plasmids. Plasmids were transfected
into HEK cells in which the luciferase expression served as readout.
To evaluate the role of the deletion in intron 8, CRISPR/Cas9 mice were generated
and crossed with mice carrying BFMI or B6N alleles. Complementation tests were performed
on the offspring.
Results All plasmids containing the SNP rs29947545 in the 5‘ UTR of the Bbs7 promoter significantly
reduced the expression of Bbs7 in HEK cells (0.35≤Fold Change ≤ 0.51, p≤0.042).
Complementation tests showed that CRISPR/Cas9 modified B6N mice partially complement
(13.1 - 15.1%) the jObes1 allele which was accompanied by a trend towards a reduced
Bbs7 expression in these mice.
Conclusion Both, a 5’ UTR-SNP and a deletion in intron 8 of Bbs7, contribute to the phenotype
of the BFMI mice most likely by reducing Bbs7 expression.
15. Versorgungsforschung | Gesundheitsökonomie | Qualitätssicherung