Rat testis motor proteins associated with spermatid translocation (dynein)and spermatid flagella (kinesin-II)

In this study, we report sites in the seminiferous epithelium of the rat te stis that are immunoreactive with antibodies to the intermediate chain of c ytoplasmic dynein and kinesin II. The study was done to determine whether o r not microtubule-dependent motor proteins are present in Sertoli cell regi ons involved with spermatid translocation. Sections and epithelial fr;fragm ents of perfusion-fixed rat testis were probed with an antibody (clone 74.1 ) to the intermediate chain of cytoplasmic dynein (IC74) and to kinesin-ll. Labeling with the antibody to cytoplasmic dynein was dramatically evident in Sertoli cell regions surrounding apical crypts containing attached sperm atids and known to contain unique intercellular attachment plaques. The ant ibody to kinesin II reacted only with spermatid tails. The levels of cytopl asmic dynein visible on immunoblots of supernatants collected from spermati d/junction complexes treated with an actin-severing enzyme (gelsolin) were greater than those of controls, indicating that at least some of the dynein may have been associated with Sertoli cell junction plaques attached to sp ermatids. Results are consistent with the conclusion that an isoform of cyt oplasmic dynein may be responsible for the apical translocation of elongate spermatids that occurs before sperm release. Also, this is the first repor t of kinesin-ll in mammalian spermatid tails.