The Novel Dominant Mutation Dspd Leads to a Severe Spermiogenesis Defect in Mice1

Authors:
  • MIMasahito Irie
    Masahito Irie
  • TOTomohisa Okutsu
    Tomohisa Okutsu
  • KIKimiko Inoue
    Kimiko Inoue
  • NONarumi Ogonuki
    Narumi Ogonuki
  • HMHiromi Miki
    Hiromi Miki
  • MYMinesuke Yokoyama
    Minesuke Yokoyama
  • RMRika Migishima
    Rika Migishima
  • KMKaori Muguruma
    Kaori Muguruma
  • HFHisako Fujimura
    Hisako Fujimura
  • AOAtsuo Ogura
    Atsuo Ogura
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Abstract
Spermiogenesis is a complex process that is regulated by a plethora of genes and interactions between germ and somatic cells. Here we report a novel mutant mouse strain that carries a transgene insertional/translocational mutation and exhibits dominant male sterility. We named the mutation dominant spermiogenesis defect (Dspd). In the testes of Dspd mutant mice, spermatids detached from the seminiferous epithelium at different steps of the differentiation process before the completion of spermiogenesis. Microinsemination using spermatids collected from the mutant testes resulted in the birth of normal offspring. These observations indicate that the major cause of Dspd infertility is (are) a defect(s) in the Sertoli cell-spermatid interaction or communication in the seminiferous tubules. Fluorescent in situ hybridization (FISH) analysis revealed a translocation between chromosomes 7F and 14C at the transgene insertion site. The deletion of a genomic region of chromosome 7F greater than 1 megabase and containing at least six genes (Cttn, Fadd, Fgf3, Fgf4, Fgf15, and Ccnd1) was associated with the translocation. Cttn encodes the actin-binding protein cortactin. Immunohistochemical analysis revealed localization of cortactin beside elongated spermatids in wild-type testes; abnormality of cortactin localization was found in mutant testes. These data suggest an important role of cortactin in Sertoli cell-spermatid interactions and in the Dspd phenotype.

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