Testis-specific sulfoglycolipid, seminolipid, is essential for germ cell function in spermatogenesis

Abstract

More than 90% of the glycolipid in mammalian testis consists of a unique sulfated glyceroglycolipid, seminolipid. The sulfation of the molecule is catalyzed by a Golgi membrane-associated sulfotransferase, cerebroside sulfotransferase (CST). Disruption of the Cst gene in mice results in male infertility due to the arrest of spermatogenesis prior to the metaphase of the first meiosis. However, the issue of which side of the cell function-germ cells or Sertoli cells-is deteriorated in this mutant mouse remains unknown. Our findings show that the defect is in the germ cell side, as evidenced by a transplantation analysis, in which wild-type spermatogonia expressing the green fluorescent protein were injected into the seminiferous tubules of CST-null testis. The transplanted GFP-positive cells generated colonies and spermatogenesis proceeded over meiosis in the mutant testis. The findings also clearly show that the seminolipid is expressed on the plasma membranes of spermatogonia, spermatocytes, spermatids, and spermatozoa, as evidenced by the immunostaining of wild-type testes using an anti-sulfogalactolipid antibody, Sulph-1 in comparison with CST-null testes as a negative control, and that seminolipid appears as early as day 8 of age, when Type B spermatogonia emerge.