Chromosome looping at the human alpha-globin locus is mediated via the major upstream regulatory element (HS -40).
Previous studies in the mouse have shown that high levels of alpha-globin gene expression in late erythropoiesis depend on long-range, physical interactions between remote upstream regulatory elements and the globin promoters. Using quantitative chromosome conformation capture (q3C), we have now analyzed all interactions between 4 such elements lying 10 to 50 kb upstream of the human alpha cluster and their interactions with the alpha-globin promoter. All of these elements interact with the alpha-globin gene in an erythroid-specific manner. These results were confirmed in a mouse model of human alpha globin expression in which the human cluster replaces the mouse cluster in situ (humanized mouse). We have also shown that expression and all of the long-range interactions depend largely on just one of these elements; removal of the previously characterized major regulatory element (called HS -40) results in loss of all the interactions and alpha-globin expression. Reinsertion of this element at an ectopic location restores both expression and the intralocus interactions. In contrast to other more complex systems involving multiple upstream elements and promoters, analysis of the human alpha-globin cluster during erythropoiesis provides a simple and tractable model to understand the mechanisms underlying long-range gene regulation.
Vernimmen
Douglas
D
Medical Research Council (MRC) Molecular Haematology Unit, Weatherall Institute for Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, OX3 9DS United Kingdom.
Marques-Kranc
Fatima
F
Sharpe
Jacqueline A
JA
Sloane-Stanley
Jacqueline A
JA
Wood
William G
WG
Wallace
Helen A C
HA
Smith
Andrew J H
AJ
Higgs
Douglas R
DR
D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D002478:Cells, Cultured; D002877:Chromosomes, Human / Q000235:genetics*; D015342:DNA Probes / Q000235:genetics; D004920:Erythropoiesis / Q000235:genetics; D005260:Female; D053263:Gene Regulatory Networks; D006801:Humans; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D005810:Multigene Family; D011401:Promoter Regions, Genetic; D050436:Regulatory Elements, Transcriptional; D055542:alpha-Globins / Q000235:genetics*
D015342:DNA Probes; D055542:alpha-Globins