Methylation of the rat seminal vesicle secretory protein IV gene. Extensive demethylation occurs in several male sex accessory glands.

Seminal vesicle secretory protein IV (SVS IV) is perhaps the most abundant protein made by the epithelial cells of the rat seminal vesicle. In this report, we have asked whether the methylation of its gene correlates with its tissue-specific pattern of expression. Using methylation-sensitive restriction endonucleases HpaII and AvaI, we could examine seven potential methylation sites in or near the gene. All seven sites were largely unmethylated in the seminal vesicle, while in most nonexpressing organs, all sites were heavily modified. The correlation of demethylation with expression was broken by finding that both ventral prostate and coagulating gland (anterior prostate) DNA showed the same demethylation pattern seen for the seminal vesicle. SVS IV protein has not been reported in either of these two organs, and we could not detect mature SVS IV message in prostate RNA or SVS IV transcription by in vitro incubation of prostate nuclei. We conclude that demethylation of the SVS IV gene accompanies the differentiation of several androgen-dependent sex accessory glands but confirm that demethylation per se is not a sufficient signal to bring about gene transcription.