Expression and localization of total Akt1 and phosphorylated Akt1 in the rat seminiferous epithelium.

Akt1 is a survival factor that is believed to play a role in the transcriptional modulation of a subset of genes associated with cell growth, proliferation, and apoptosis. We have explored in detail the expression of total Akt1 and phosphorylated Akt1 in the developing and adult rat testis. Throughout testis postnatal development, the expression of total Akt1 protein exhibited a mainly cytoplasmic localization within both the germ cells and the supporting Sertoli cells. In contrast, phosphorylated Akt1 staining demonstrated a mainly nuclear localization within germ cells. In the developmental sequence of germ cells, phosphorylated Akt1 stained the nuclei of spermatogonia, spermatocytes, and round spermatids. During spermiogenesis, phosphorylated Akt1 staining decreased in the nucleus and became localized to a bright spot at the base of the nucleus in elongate spermatids. Of interest, total Akt1 was found to localize to the perinuclear region of germ cells and the supranuclear region of Sertoli cells, depending on fixation. Further analysis demonstrated this staining to be associated with the Golgi complex in both germ and Sertoli cells.