[Tissue-specific expression of human endogenous retrovirus mRNA and its regulation by cytokines in vitro]

To investigate biological roles of human endogenous retroviruses (ERVs), the author examined the viral mRNA expression in the normal systemic organs in vivo and its regulation by cytokines in cultured cells. The following evidence suggesting biological activities of a human ERV, ERV3, was obtained. First, the ERV3 mRNA was demonstrated at different levels in organs, and at consistently high levels in adrenal glands from all individuals and in all adrenocortical adenomas examined, by Northern hybridization. In situ hybridization revealed that the ERV3 expression was localized in all three layers of the adrenal cortex, but not in the medulla. These results suggest that the ERV3 expression may relate to the cellular differentiation and/or steroid production of adrenocortical cells. Second, the amount of ERV3 mRNA in cultured endothelial cells from human umbilical vein was significantly increased with any of TNF-alpha, IL-1 beta or IL-1 alpha stimulation but decreased with IFN-gamma treatment, by a quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) with competitive PCR. The collective evidence suggests that the ERV3 expression may be upregulated at the inflammatory sites of vessels in vivo, and that the ERV3 expression may, therefore, play certain pathogenic roles in diseases, including collagen and vascular diseases in man.