HYPOMETHYLATION OF DNA DERIVED FROM PURIFIED HUMAN ERYTHROID-CELLS CORRELATES WITH GENE ACTIVITY OF THE BETA-GLOBIN CLUSTER

  • 1 January 1985
    • journal article
    • research article
    • Vol. 66  (5) , 1202-1207
Abstract
Analysis of methylation at the .beta.-globin gene cluster was carried out on DNA derived from nucleated RBCs (orthochromatic normoblasts) isolated from peripheral blood of patients with .beta.-thalassemia major or other congenital hemolytic anemia after splenectomy. A procedure to separate these normoblasts from the other nucleated cells of the peripheral blood was developed, providing us with a convenient source of DNA for investigating parameters related to human erythroid differentiation. Blood samples were obtained from six adult patients who express their .gamma.-globin genes at different levels. Inverse correlation between methylation and gene activity was consistently observed for five of the either sites analyzed. A site 3'' to the .beta. gene was always unmethylated, two sites flanking the .epsilon. gene were always found to be methylated, and two sites 5 to the two .gamma. genes, G.gamma. and A.gamma., were hypomethylated in correlation with .gamma. gene activity of the individual patients. A site 5'' to the .delta. gene was unmethylated in normoblasts as well as in WBC. No apparent relation between hypomethylation and gene activity was observed for two additional sites. The results suggest that methylation at specific chromosomal locations participate in genetic regulation of the .beta.-like globin genes in hymans.