Harima, R.; Hara, K.; Tanemura, K.

Flagella and cilia are widely conserved motile structures. Mammalian sperm possess flagella, which confer motility to the sperm and, therefore, are essential for fertilization. Large protein complexes called dynein, including cytoplasmic dynein 2 and axonemal dynein, play a role in the formation of cilia and flagella. The function of each dynein complex subunit in sperm flagellum formation is unclear. One such subunit is TCTEX1D2. Tctex1d2 -/- mice generated in this study showed male infertility because of flagellar dysplasia arising from round spermatids and disruption of the axonemal structure inside the flagella. In contrast, the motile cilia of Tctex1d2 -/- mice were normal. Co-immunoprecipitation studies showed that TCTEX1D2 interacted with the cytoplasmic dynein 2 component proteins WDR34, WDR60, and DYNLT1 in the testes and that the localization of these proteins was abnormal in Tctex1d2 -/- mice. Furthermore, TCTEX1D2 also interacted with WDR63 and WDR78, component proteins of the inner dynein arm, which is axonemal dynein. Overall, we revealed that TCTEX1D2 has two distinct functions in mouse sperm flagellum formation the assembly of cytoplasmic dynein 2 and organization of inner dynein arm which is not the case in cilia formation where TCTEX1D2 functions only as cytoplasmic dynein 2.