The development of male contraceptives is highly desirable, as worldwide there is a large unmet need for alternative methods for family planning. Therefore, it is important to identify and investigate ways, by which male fertility can be regulated. Oral administration of the alkylated imino sugars N-butyldeoxynojirimycin (NB-DNJ) and N-butyldeoxygalactonojirimycin (NB-DGJ) causes reversible infertility in male mice. The mice are infertile because they produce morphologically abnormal spermatozoa that are mostly without acrosomes, and have reduced motility. To understand the chain of events underlying this phenomenon, the long-term objectives are the following: (1) Identify the biochemical processes that are modulated, directly, or indirectly, by alkylated imino sugars that cause male mice to be infertile; (2) Correlate these biochemical changes with the cell biological peculiarities seen in testes from mice after administration of alkylated imino sugars. ? ? The proposed research has three components. (1) Significance of known drug targets. Investigated will be whether male infertility is caused by inhibition of one of the known targets of NB-DNJ and NB-DGJ, which are the ceramide-speciflc glucosyltransferase and a non-lysosomal glucosylceramidase. These enzymes are involved in the metabolism of a glycosphingolipid, glucosylceramide. Assessed will be the effects of NB-DNJ on the level of testicular glucosylceramide, as well as its cellular and subcellular distribution, and the localization of the enzyme that is the primary drug target. (2) Novel drug targets. Since the alkylated imino sugars are ceramide-mimics, it is essential to establish whether these compounds also affect the metabolism of glycolipids other than glucosylceramide. This may lead to the identification of additional drug targets. (3) Consequences of altered glycosphingolipid metabolism for male germ cell development. The following aspects of the biochemistry and cell biology of spermatids will be studied: crosstalk between sphingolipid and phospholipid metabolism, the lipid and protein composition of sphingolipid/cholesterol-enriched microdomains, trafficking and turnover of acrosomal proteins, and ultrastructure. To develop reagents for the investigation of acrosome development, a proteomic analysis of this organelle will be performed. ? ?
