Presence of Multiple Fucosyltransferases in Rat Sertoli Cells and Spermatogenic Cells

Abstract

Differential expression of fucosyltransferases (FTs) on Sertoli cell and germ cell surfaces and their function as ectoenzymes may be important in the process of spermatogenesis. To determine the glycosidic linkage specificity of FTs present in cultured Sertoli cells and in germ cells, we quantified FT activities by thin-layer chromatography using both high and low molecular weight acceptors in the presence of GDP-[¹⁴C]-L-fucose. Analysis of the acceptor substrate specificity of the FTs indicated that α(1–2), α(1–3), α(1–4)-FTs are expressed as demonstrated by fucose incorporation into phenyl-β-D-galactoside, 2′-fucosyllactose, and lacto-N-fucopentaose-I, respectively. In Sertoli cells, the ratios of the three FTs examined were the same for whole-cell extracts and samples of purified plasma membranes. Higher relative FT activity was observed in plasma membranes from mixed germ cells than in Sertoli cell membranes. Furthermore, α(1–3)-FT and α(l–4)-FT activities were higher in mixed germ cell membranes. Spermatogenic stage specificity of FT expression was assessed in purified populations of germ cells. With calculation on a per-cell basis, all three α-FTs exhibited a quantitative decrease during the transition between pachytene spermatocytes and round spermatids. The decrease in α(1–3)-FT activity was particularly significant. In rat germ cells, all three α-FT activities associated with the cell surface in pachytene spermatocytes and round spermatids were 34–53% and 52–53%, respectively, of the total cell FT activity. These results demonstrate that a family of cell surface FTs is expressed on cells of the seminiferous epithelium and suggest that these enzymes may be involved in testicular cell differentiation during spermatogenesis.