Up-regulation and down-regulation of genes expressed in cocultures of rat Sertoli cells and germ cells.

To better understand the molecular interactions between somatic and germ cells in the mammalian testis, we have begun to analyze with mRNA differential display changes in gene expression induced by coculturing rat Sertoli cells and germ cells. We have identified 10 cDNAs that are either down-regulated or up-regulated in cocultures of germ cells and Sertoli cells. Three genes expressed in Sertoli cells and three genes expressed in germ cells were down-regulated in Sertoli cell-germ cell cocultures, whereas four genes were up-regulated in the cocultures. Northern blot analysis was used to establish the expression pattern of the mRNAs encoded by the cDNAs and to define the sizes of the differentially expressed mRNAs. Sequence analysis of the cDNAs and computer searches against the GenBank and EMBL DNA databases were used to relate the ten cDNAs to known genes. Of the three Sertoli cell cDNAs, one appeared identical to transferin, while the other two shared regions of similarity to an endoplasmic reticulum stress protein and to a pro-alpha 2 XI collagen, respectively. The three germ cell cDNAs shared sequences with fibronectin, with a basic fibroblast growth factor receptor and with an IgG gamma 2b, respectively. The four cDNAs that were up-regulated in the Sertoli-germ cell cocultures showed similarity to an isoform of casein kinase 1 delta, to an epidermal growth factor, to a statin-related protein, and to an integral membrane glycoprotein. These data demonstrate that a number of specific genes are up- and down-regulated when germ cells and Sertoli cells are cocultured, and suggest these genes are important in cell to cell communication during spermatogenesis.