Differential gene expression detected by suppression subtractive hybridization in the ethylene glycol monomethyl ether-induced testicular lesion.

The solvent ethylene glycol monomethyl ether (EGME) produces the same testicular lesions in rodents and human testis cultures, whose onset is characterized by apoptosis of pachytene spermatocytes. To identify gene changes early in the lesion and determine the possible involvement of cells other than the spermatocytes, we employed a suppression subtractive hybridization technique using whole testes from mice treated 8 h previously with 500 mg/kg EGME to generate two subtracted mouse testis cDNA libraries enriched for gene populations either up-regulated or down-regulated by EGME. A total of 70 clones were screened, and 6 of them were shown by Northern blotting to be differentially expressed in the EGME lesion. The three clones with increased expression after EGME treatment were identical to t-complex testis expressed gene 1 (tctex1), a gene encoding ribosomal protein S25, and a heretofore uncharacterized mouse testis expressed sequence tag. Three other genes suppressed by EGME were tctex2, alpha-2,6-sialyltransferase gene, and another uncharacterized mouse testis expressed sequence tag. Predicted peptide sequences of these clones contain multiple motifs for phosphorylation, glycosylation, and myristoylation. In situ hybridization with the antisense RNA probes further supported the expression changes of these six clones and localized the changes in multiple germ cell stages as well as other cell types (Sertoli, interstitial and peritubular cells). These data at the gene expression level are the first to demonstrate the early involvement in this lesion of cell types other than the dying spermatocytes.