Normal spermatogenesis in Fank1 (fibronectin type 3 and ankyrin repeat domains 1) mutant mice

BACKGROUND: The fibronectin type 3 and ankyrin repeat domains 1 gene, Fank1, is an ancient, evolutionarily conserved gene present in vertebrates. Short-hairpin RNA (shRNA)-based knockdown transgenic mice have oligospermia caused by an increase in apoptotic germ cells. In this study, we investigated the in vivo function of Fank1. METHODS: In this study, we generated Fank1-knockout mice using the CRISPR/Cas9 system. We then investigated the phenotype and in vivo function of Fank1. Testes and epididymis tissues were analyzed by histological and immunofluorescence staining. Apoptotic cells were analyzed in terminal deoxynucleotidyl transferase dUTP nick end-labeling assays. Fertility and sperm counts were also evaluated. The GTEx database were used to assess gene expression quantitative trait loci and mRNA expression of candidate genes and genes neighboring single nucleotide polymorphisms was analyzed by quantitative RT-PCR. RESULTS: In contrast to the Fank1-knockdown model, no significant changes in epididymal sperm content and the number of apoptotic cells were observed in Fank1−/− homozygotes. In addition, a different pattern of Dusp1, Klk1b21 and Klk1b27 mRNA expression was detected in Fank1-knockout testis. These results reveal differences in the molecular changes between Fank1-knockdown mice and Fank1-knockout mice and provide a basic resource for population genetics studies.