A long terminal repeat of the human endogenous retrovirus ERV-9 is locatedin the 5 ' boundary area of the human beta-globin locus control region

Transcription of the human p-like globin genes in erythroid cells is regula ted by the far-upstream locus control region (LCR). In an attempt to define the 5' border of the LCR, we have cloned and sequenced 5 kb of new upstrea m DNA. We found an LTR retrotransposon belonging to the ERV-9 family of hum an endogenous retroviruses in the apparent 5' boundary area of the LCR. Thi s ERV-9 LTR contains an unusual U3 enhancer region composed of 14 tandem re peats with recurrent GATA, CACCC, and CCAAT motifs. This LTR is conserved i n human and gorilla, indicating its evolutionary stability in the genomes o f the higher primates. In both recombinant constructs and the endogenous hu man genome, the LTR enhancer and promoter activate the transcription of cis -linked DNA preferentially in erythroid cells. Our findings suggest the pos sibility that this LTR retrotransposon may serve a relevant host function i n regulating the transcription of the beta-globin LCR. (C) 1998 Academic Pr ess.