Intracellular Localization of the Microtubule-Associated Motor Proteins Kinesin and Cytoplasmic Dynein in Rat Sertoli Cells

Abstract

The expression of cytoplasmic dynein and kinesin in rat Sertoli cells was examined using immunohistochemistry with light and electron microscopies, and the existence of such bi-directional motors in the cells was confirmed. Cytoplasmic dynein was localized in the ectoplasmic specializations (ESs), mitochondria, and endoplasmic reticula. Among microtubules, an intense reaction of dynein was also detected, while, the reaction of kinesin changed in intensity in a stage-dependent manner. The most distinct reaction of kinesin in Sertoli cells was detected at stages VII-VIII, while a weak reaction was observed at stages IX-XIV. No positive reaction was detected at stages I-VI. The intracellular localization of kinesin was detected in the ES (stage X) and endoplasmic reticulum, but a defined reaction was not observed among microtubules. These results suggested that an active bi-directional organelle transport is performed in rat Sertoli cells, and the system may relate to the elongation and release of spermatids, and to the migration of membranous organelles such as mitochondria and endoplasmic reticula. In addition, the sliding movement of microtubules may be carried out mainly by cytoplasmic dynein.