Synthetic human beta-globin 5'HS2 constructs function as locus control regions only in multicopy transgene concatamers.
Transgenes linked to the beta-globin locus control region (LCR) are transcribed in a copy-dependent manner that is independent of the integration site. It has previously been shown that the LCR 5'HS2 region does not require its NF-E2 dimer binding site for LCR activity. In this paper we analyse synthetic 5'HS2 core constructs containing point mutations in the other factor binding sites 3' of the NF-E2 dimer site. The results show that 5'HS2 core is a partially active LCR that functions in a concatamer of at least two copies but not when present as a single copy in transgenic mice and that no single binding site within 5'HS2 is required for position-independent expression. In addition, the H-BP factor is identical to upstream stimulatory factor (USF) and full enhancement levels by 5'HS2 core in MEL cells require a combination of all the factor binding sites. We suggest that 5'HS2 cores in a concatamer interact with each other to establish an area of open chromatin and that this process may be the basis of LCR function.
Ellis
J
J
Laboratory of Gene Structure and Expression, National Institute for Medical Research, London, UK.
Talbot
D
D
Dillon
N
N
Grosveld
F
F
D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D004247:DNA / Q000235:genetics / Q000302:isolation & purification; D004268:DNA-Binding Proteins / Q000235:genetics; D050981:Erythroid-Specific DNA-Binding Factors; D005333:Fetus; D005809:Genes, Regulator; D005813:Genes, Synthetic; D005914:Globins / Q000235:genetics*; D006801:Humans; D007438:Introns; D008099:Liver / Q000502:physiology; D051379:Mice; D008822:Mice, Transgenic; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D050983:NF-E2 Transcription Factor; D050984:NF-E2 Transcription Factor, p45 Subunit; D015183:Restriction Mapping; D014157:Transcription Factors / Q000235:genetics; D014162:Transfection; D016335:Zinc Fingers / Q000235:genetics
D004268:DNA-Binding Proteins; D050981:Erythroid-Specific DNA-Binding Factors; 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; D004247:DNA