DISTRIBUTION OF GELSOLIN IN HUMAN TESTIS

Gelsolin, an actin-binding and severing protein present in many mammal ian cells, was characterized in human testis. Although abundant in tes ticular extracts, gelsolin was not detected in purified spermatogenic cells by immunoblot analysis. Immunofluorescence studies of testis sec tions showed that gelsolin has two main localizations: peritubular cel ls and the seminiferous epithelium. In peritubular cells, gelsolin was present together with alpha-SM actin, in agreement with the myoid cel l characteristics of these cells. In a large proportion of the tubules , gelsolin was found mainly, together with actin, in the apical part o f 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 Se rtoli cells. However, in normal testis, a complex pattern of gelsolin labeling was also present, mostly in the apical third of the epitheliu m, around cells or groups of cells, mainly spermatids, and, less frequ ently, in various other localizations from the apical to the basal par t of the seminiferous epithelium. Taken together, these observations s uggest that gelsolin may play different functions in the seminiferous epithelium: (1) regulation of the dynamic alterations of the actin cyt oskeleton in the apical cytoplasm of Sertoli cells, and (2) modificati on of actin filaments assemblies in specific structures at germ cell-S ertoli cell contacts. Thereby, the actin-modulating properties of gels olin are probably involved in reorganization of the seminiferous epith elium related to germ cell differentiation. (C) 1997 Wiley-Liss, Inc.