Hypersensitive site 5 of the human β locus control region functions as a chromatin insulator

Abstract

The human β locus control region (LCR) consists of five DNAse I hypersensitive sites (HS), four of which are erythroid specific and one, the further upstream located 5'HS5, is constitutive. To characterize the function of 5'HS5 we analyzed globin gene expression of various constructs containing HS3 as an enhancer, HS5, and the β gene as a reporter. Expression was analyzed in stably transfected MEL cells. We found that the enhancing effect of hypersensitive site 3 is blocked when the HS5 is interposed between HS3 and the β globin gene. These data suggest that the human 5'HS5 has the properties of a chromatin insulator.