Structural analysis and mapping of DNase I hypersensitivity of HS5 of the beta-globin locus control region.
The beta-globin locus control region (LCR) is a cis regulatory element that is located in the 5' part of the locus and confers high-level erythroid lineage-specific and position-independent expression of the globin genes. The LCR is composed of five DNase I hypersensitive sites (HSs), four of which are formed in erythroid cells. The function of the 5'-most site, HS5, remains unknown. To gain insights into its function, mouse HS5 was cloned and sequenced. Comparison of the HS5 sequences of mouse, human, and galago revealed two extensively conserved regions, designated HS5A and HS5B. DNase I hypersensitivity mapping revealed that two hypersensitive sites are located within the HS5A region (designated HS5A(major) and HS5A(minor)), and two are located within the HS5B region (HS5B(major), HS5B(minor)). The positions of each of these HSs colocalize with either GATA-1 or Ap1/NF-E2 motifs, suggesting that these protein binding sites are implicated in the formation of HS5. Gel retardation assays indicated that the Ap1/NF-E2 motifs identified in murine HS5A and HS5B interact with NF-E2 or similar proteins. Studies of primary murine cells showed that HS5 is formed in all hemopoietic tissues tested (fetal liver, adult thymus, and spleen), indicating that this HS is not erythroid lineage specific. HS5 was detected in murine brain but not in murine kidney or adult liver, suggesting that this site is not ubiquitous. The presence of GATA-1 and NF-E2 motifs (which are common features of the DNase I hypersensitive sites of the LCR) suggests that the HS5 is organized in a manner similar to that of the other HSs. Taken together, our results suggest that HS5 is an inherent component of the beta-globin locus control region.
Li
Q
Q
School of Medicine, University of Washington, Seattle, Washington, 98195, USA.
Zhang
M
M
Duan
Z
Z
Stamatoyannopoulos
G
G
D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D003001:Cloning, Molecular; D017124:Conserved Sequence; D004268:DNA-Binding Proteins / Q000378:metabolism; D003850:Deoxyribonuclease I / Q000737:chemistry*; D050981:Erythroid-Specific DNA-Binding Factors; D050982:GATA1 Transcription Factor; D005701:Galago; D005914:Globins / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D006413:Hematopoietic System / Q000378:metabolism; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D050983:NF-E2 Transcription Factor; D050984:NF-E2 Transcription Factor, p45 Subunit; D020161:Physical Chromosome Mapping; D012045:Regulatory Sequences, Nucleic Acid; D016415:Sequence Alignment; D014157:Transcription Factors / Q000378:metabolism
D004268:DNA-Binding Proteins; D050981:Erythroid-Specific DNA-Binding Factors; D050982:GATA1 Transcription Factor; C494688:GATA1 protein, human; C494689:Gata1 protein, mouse; D050983:NF-E2 Transcription Factor; D050984:NF-E2 Transcription Factor, p45 Subunit; C494692:NFE2 protein, human; C494693:Nfe2 protein, mouse; D014157:Transcription Factors; D005914:Globins; D003850:Deoxyribonuclease I