| Abstract: | Gelsolin, an actin-binding and severing protein present in many mammalian cells, was characterized in human testis. Although abundant in testicular extracts, gelsolin was not detected in purified spermatogenic cells by immunoblot analysis. Immunofluorescence studies of testis sections showed that gelsolin has two main localizations: peritubular cells and the seminiferous epithelium. In peritubular cells, gelsolin was present together with α-SM actin, in agreement with the myoid cell characteristics of these cells. In a large proportion of the tubules, gelsolin was found mainly, together with actin, in the apical part of the seminiferous epithelium. This localization of gelsolin also was observed in seminiferous tubules with a partial or complete absence of germinal cells, which evokes a presence of gelsolin at the apex of Sertoli cells. However, in normal testis, a complex pattern of gelsolin labeling was also present, mostly in the apical third of the epithelium, around cells or groups of cells, mainly spermatids, and, less frequently, in various other localizations from the apical to the basal part of the seminiferous epithelium. Taken together, these observations suggest that gelsolin may play different functions in the seminiferous epithelium: (1) regulation of the dynamic alterations of the actin cytoskeleton in the apical cytoplasm of Sertoli cells, and (2) modification of actin filaments assemblies in specific structures at germ cell-Sertoli cell contacts. Thereby, the actin-modulating properties of gelsolin are probably involved in reorganization of the seminiferous epithelium related to germ cell differentiation. Mol. Reprod. Dev. 48:63–70, 1997. © 1997 Wiley-Liss, Inc. |
