CONICET | Buscador de Institutos y Recursos Humanos

Germ cells from male rodents require membrane sphingolipids (SL) with very-long-chain polyunsaturated fatty acids (VLCPUFA), in non-hydroxylated (n-V) and 2-hydroxylated (h-V) versions, for normal spermatogenesis. We are showing that spermatogenic cells isolated from seminiferous tubules of adult rats, in culture, are able to synthesize ceramides (Cer), sphingomyelins (SM), and glucosylceramides (GlcCer), including species with VLCPUFA. By using [3H]16:0 as precursor, such an ability is shown here to be maximal in pachytene spermatocytes (PtS) and to decrease with differentiation to round spermatids (RS). As measured by RT-qPCR, the mRNA levels of the SL synthases CerS3 and GlcCerS were higher in PtS than in RS, those of SMS1 were similar, while those of SMS2 were higher in RS than in PtS. Next, we evaluated the effect on SL biosynthesis and gene expression of supplementing the cultures with testosterone (Tes), with Sertoli cell-conditioned medium (SCM), and with both together. In the presence of Tes, the synthesis of Cer from [3H]16:0 was not affected in PtS and RS, while that of SM was increased significantly in RS. In the presence of SCM, the labeling of Cer was stimulated in PtS and RS, whereas in RS that of SM increased and that of GlcCer decreased. Supplementation with SCM plus Tes increased the incorporation of [3H]16:0 into n-V species of SM, and the transcript levels of SMS2, in PtS. In RS, this combination increased the formation of n-V species of [3H]Cer, and the transcript levels of Elovl4 and CerS3, enzymes responsible, respectively, for the synthesis of n-V and of Cer species containing n-V. Our results indicate that the de novo biosynthesis of SL in spermatogenic cells during the course of differentiation is coordinately regulated by Tes and by soluble factor(s) released from Sertoli cells. Supported by SGCyT UNS-PGI-UNS [24/B272 to GMO and 24/B218 to MIA], FONCyT , [PICT2017-2535 to GMO].