Murine prosaposin: expression in the reproductive system of a gene implicated in human genetic diseases

Expression of the prosaposin gene, implicated in human genetic diseases, was studied in the mouse by Northern blot analysis and in situ hybridization. Using a cloned mouse prosaposin cDNA as a probe, we observed high expression of the prosaposin gene in the adult and embryonic nervous and reproductive systems while lower levels of prosaposin mRNA were detected in the heart, kidneys, liver, adrenals and lymphoid organs. Ubiquitous low level of prosaposin mRNA were detected by in situ hybridization in 12.5 days-old embryos. However, high expression was restricted to the hindbrain, the dorsal ganglia and to the genital ridge, the primordium for both male and female gonads. RNA transcription in the testis was detected in Sertoli cells, Leydig cells and peritubular cells but not in germ cells of adult mice. Similar observations were obtained with the atrichosis mutant mouse known to lack normal germ cells, indicating that prosaposin gene expression was not dependent on the presence of germ cells in the testis. Prosaposin was found to be expressed in the mature female gonads at various stages of the corpus luteum development. These results strongly suggest that prosaposin may play an important role in the reproductive system as well as the nervous system.