ELEVATED LEVELS OF THE ENDOGENOUS RETROVIRUS ERV3 IN HUMAN SEBACEOUS GLANDS

ERV3 (HERV-R) is a complete human endogenous retrovirus located on the long arm of chromosome 7. Long terminal repeat-envelope (env) gene sp liced mRNAs of 9 and 3.5 kb are widely expressed in human tissues and cells, but gag-pol mRNAs have not been found, Furthermore, the env gp7 0 gene contains an open reading frame throughout its length, The highe st expression of ERV3 mRNA detected so far is in placenta and the lowe st in choriocarcinoma cell lines. We have previously shown that the hu man monoblastic cell line U-937 and some normal and neoplastic tissues also express high levels of ERV3 env message by Northern blot analysi s; however, this method does not distinguish between mRNA expression i n different cell types in tissues. In this report, we have studied the ERV3 mRNA expression in specific cell types of human skin by in situ hybridization. We found high levels expression of ERV3 env mRNA in hum an sebaceous glands in normal skin and dermoid cysts of the ovary. In all glands, the expression is maximal in the periphery of the lobule a nd ceases towards the center in the region of characteristic holocrine secretion. Since it is known that the regulation of sebaceous glands is primarily via steroid hormones, particularly androgens, it is possi ble that expression of ERV3 is hormone dependent.