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Molecular and Cellular Biology, July 2008, p. 4386-4393, Vol. 28, No. 13
0270-7306/08/$08.00+0 doi:10.1128/MCB.00071-08
Copyright © 2008, American Society for Microbiology. All Rights Reserved.
A T-to-G Transversion at Nucleotide –567 Upstream of HBG2 in a GATA-1 Binding Motif Is Associated with Elevated Hemoglobin F
Zhiyi Chen,1,
Hong-Yuan Luo,1,
Raveen K. Basran,1
Tien-Huei Hsu,1
Daniel W. H. Mang,1
Lalana Nuntakarn,1
Cathy G. Rosenfield,3
George P. Patrinos,4
Ross C. Hardison,5
Martin H. Steinberg,1,2 and
David H. K. Chui1,2*
Center of Excellence in Sickle Cell Disease, Division of Hematology/Oncology, Department of Medicine,1 Department of Pathology and Laboratory Medicine, Boston University School of Medicine, Boston, Massachusetts 02118,2 Department of Pediatrics, Tufts Medical Center, Boston, Massachusetts 02111,3 MGC-Department of Cell Biology and Genetics, Erasmus MC, Faculty of Medicine and Health Sciences, Rotterdam, The Netherlands,4 Center for Comparative Genomics and Bioinformatics, Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 168025
Received 14 January 2008/ Returned for modification 10 February 2008/ Accepted 5 April 2008
Increased fetal hemoglobin (Hb F; 
2
2) production in adults can ameliorate the clinical severity of sickle cell disease and β-thalassemia major. Thus, understanding the regulation of -globin gene expression and its silencing in adults has potential therapeutic implications. We studied a father and son in an Iranian-American family who had elevated Hb F levels and found a novel T-to-G transversion at nucleotide (nt) –567 of the HBG2 promoter. This mutation alters a GATA-1 binding motif to a GAGA sequence located within a previously identified silencing element. DNA-protein binding assays showed that the GATA motif of interest is capable of binding GATA-1 transcription factor in vitro and in vivo. Truncation analyses of the HBG2 promoter linked to a luciferase reporter gene revealed a negative regulatory activity present between nt –675 and –526. In addition, the T-to-G mutation at the GATA motif increased the promoter activity by two- to threefold in transiently transfected erythroid cell lines. The binding motif is uniquely conserved in simian primates with a fetal pattern of -globin gene expression. These results suggest that the GATA motif under study has a functional role in silencing -globin gene expression in adults. The T-to-G mutation in this motif disrupts GATA-1 binding and the associated repressor complex, abolishing its silencing effect and resulting in the up-regulation of -globin gene expression in adults.
* Corresponding author. Mailing address: Evans 248, Department of Medicine, Boston University School of Medicine, 88 East Newton Street, Boston, MA 02118. Phone: (617) 414-1018. Fax: (617) 414-1021. E-mail: david.chui{at}bmc.org
Published ahead of print on 28 April 2008.
Z.C. and H.-Y.L. contributed equally to this work.
Molecular and Cellular Biology, July 2008, p. 4386-4393, Vol. 28, No. 13
0270-7306/08/$08.00+0 doi:10.1128/MCB.00071-08
Copyright © 2008, American Society for Microbiology. All Rights Reserved.
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