Comparative analysis of the locus control region of the rabbit β-like globin gene cluster: HS3 increases transient expression of an embryonic ε-globin gene

The rabbit homolog to the locus control region (LCR) of the human β-like globln gene cluster was isolated, and long segments containing the DNase I hypersensitive sites (HS) were sequenced. The order and spacing of HS4, HS3, HS2 and HS1 are conserved between rabbit and human. Alignment of these sequences with their homologs from human, goat, and mouse shows that very long segments of DNA match between species, for over a thousand base pairs on either side of the previously identified functional cores, Indicating that some important functions are found outside the cores. The activity of rabbit HS2 and HS3 was tested by attaching each to a novel reporter gene constructed by inserting the luciferase coding region into the rabbit ε-globln gene. In contrast to previous reports showing no effect of human or mouse HS3 on transient expression, both the rabbit HS2 and HS3 DNA fragments separately increased transient expression from the ε-luciferase hybrid gene and expression from stably Integrated constructs in K562 erythroleukemia cells.