Characterization of cholesterol metabolism in Sertoli cells and spermatogenesis

The Sertoli cell, which is the supporting cell of spermatogenesis, has an important role in the endocrine and paracrine control of spermatogenesis. Functionally, it provides the cells of the seminiferous epithelium with nutrition, conveys mature spermatids to the lumen of seminiferous tubules, secretes androgen-binding protein and interacts with endocrine Leydig cells. In addition, the levels of cholesterol, as well as its intermediates, vary greatly between nongonadal tissues and the male reproductive system. Throughout spermatogenesis, a dynamic and constant alteration in the membrane lipid composition of Sertoli cells occurs. In several mammalian species, testis meiosis-activating sterol and desmosterol, as well as other cholesterol precursors, accumulate in the testes and spermatozoa. In addition, certain cholesterogenic genes exhibit stage-specific expression patterns during spermatogenesis, including the cytochrome P450 enzyme lanosterol 14α-demethylase. Inconsistency in the patterns of gene expression during spermatogenesis indicates a cell-type specific and complex temporary modulation of lipids and cholesterol, which also implicates the dynamic interactions between Sertoli cells and germ cells. Furthermore, in the female reproductive tract and during epididymal transit, which is a prerequisite for valid fertilization, the modulation of cholesterol occurring in spermatozoal membranes further indicates the functional importance of sterol compounds in spermatogenesis. However, the exact role of cholesterol metabolism in Sertoli cells in sperm production is unknown. The present review article describes the progress made in the research regarding the characteristics of the Sertoli cell, particularly the regulation of its cholesterol metabolism during spermatogenesis.