An embryonic-specific repressor element located 3' to the Agamma-globin gene influences transcription of the human beta-globin locus in transgenic mice

TY - JOUR

T1 - An embryonic-specific repressor element located 3' to the Agamma-globin gene influences transcription of the human beta-globin locus in transgenic mice

AU - Katsantoni, Eleni Z

AU - de Krom, Mariken

AU - Kong-a-San, John

AU - Imam, A M Ali

AU - Grosveld, Frank

AU - Anagnou, Nicholas P

AU - Strouboulis, John

PY - 2004/2

Y1 - 2004/2

N2 - OBJECTIVE: Persistent expression of the human fetal gamma-globin genes in the adult stage is often associated with naturally occurring deletions in the human beta-globin locus. The mapping of the 5' breakpoints of these deletions within the Agamma- to delta-globin intergenic region has suggested that regulatory elements involved in the silencing of the gamma-globin genes in the adult may be present. We previously identified two elements in this region, termed Enh and F, located 3' to the Agamma-globin gene acting as silencers in transient transfection assays. Here, we tested directly the in vivo significance of these elements in the developmental regulation of the human beta-like globin genes. MATERIALS AND METHODS. We selectively deleted both Enh and F elements in the context of a 185-kb human beta-globin locus PAC (P1 phage artificial chromosome) and tested the effects of this deletion on the expression of the human P-like globin genes in transgenic mice.RESULTS: The Enh/F deletion resulted in an increase in epsilon- and gamma-globin mRNA levels in the embryonic yolk sac stage of erythropoiesis, which appears to be due to an increase in the rate of transcription rather than to an increase in the number of cells transcribing the human globin locus. However, the human developmental switching from fetal gamma-globin to adult beta-globin gene expression in transgenic mice was not affected by this deletion.CONCLUSION: These results identify Enh and F as locus-wide regulatory elements capable of down-regulating transcription of the human beta-globin locus in an embryonic-specific manner.

AB - OBJECTIVE: Persistent expression of the human fetal gamma-globin genes in the adult stage is often associated with naturally occurring deletions in the human beta-globin locus. The mapping of the 5' breakpoints of these deletions within the Agamma- to delta-globin intergenic region has suggested that regulatory elements involved in the silencing of the gamma-globin genes in the adult may be present. We previously identified two elements in this region, termed Enh and F, located 3' to the Agamma-globin gene acting as silencers in transient transfection assays. Here, we tested directly the in vivo significance of these elements in the developmental regulation of the human beta-like globin genes. MATERIALS AND METHODS. We selectively deleted both Enh and F elements in the context of a 185-kb human beta-globin locus PAC (P1 phage artificial chromosome) and tested the effects of this deletion on the expression of the human P-like globin genes in transgenic mice.RESULTS: The Enh/F deletion resulted in an increase in epsilon- and gamma-globin mRNA levels in the embryonic yolk sac stage of erythropoiesis, which appears to be due to an increase in the rate of transcription rather than to an increase in the number of cells transcribing the human globin locus. However, the human developmental switching from fetal gamma-globin to adult beta-globin gene expression in transgenic mice was not affected by this deletion.CONCLUSION: These results identify Enh and F as locus-wide regulatory elements capable of down-regulating transcription of the human beta-globin locus in an embryonic-specific manner.

KW - Animals

KW - Chromosome Mapping

KW - Embryo, Mammalian/metabolism

KW - Escherichia coli/genetics

KW - Gene Deletion

KW - Gene Expression Regulation, Developmental

KW - Globins/genetics

KW - Humans

KW - In Situ Hybridization

KW - Mice

KW - Mice, Transgenic

KW - Recombination, Genetic

KW - Repressor Proteins/physiology

U2 - 10.1016/j.exphem.2003.11.001

DO - 10.1016/j.exphem.2003.11.001

M3 - Article

C2 - 15102485

SN - 0301-472X

VL - 32

SP - 224

EP - 233

JO - Experimental Hematology

JF - Experimental Hematology

IS - 2

ER -