The locus control region is required for association of the murine beta-globin locus with engaged transcription factories during erythroid maturation.
We have examined the relationship between nuclear localization and transcriptional activity of the endogenous murine beta-globin locus during erythroid differentiation. Murine fetal liver cells were separated into distinct erythroid maturation stages by fluorescence-activated cell sorting, and the nuclear position of the locus was determined at each stage. We find that the beta-globin locus progressively moves away from the nuclear periphery with increasing maturation. Contrary to the prevailing notion that the nuclear periphery is a repressive compartment in mammalian cells, beta(major)-globin expression begins at the nuclear periphery prior to relocalization. However, relocation of the locus to the nuclear interior with maturation is accompanied by an increase in beta(major)-globin transcription. The distribution of nuclear polymerase II (Pol II) foci also changes with erythroid differentiation: Transcription factories decrease in number and contract toward the nuclear interior. Moreover, both efficient relocalization of the beta-globin locus from the periphery and its association with hyperphosphorylated Pol II transcription factories require the locus control region (LCR). These results suggest that the LCR-dependent association of the beta-globin locus with transcriptionally engaged Pol II foci provides the driving force for relocalization of the locus toward the nuclear interior during erythroid maturation.
Ragoczy
Tobias
T
Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington, Washington 98109, USA.
Bender
M A
MA
Telling
Agnes
A
Byron
Rachel
R
Groudine
Mark
M
D000818:Animals; D002454:Cell Differentiation; D002467:Cell Nucleus / Q000235:genetics; D041905:Erythroid Cells / Q000378:metabolism*; D005914:Globins / Q000235:genetics*; D017404:In Situ Hybridization, Fluorescence; D008099:Liver / Q000166:cytology / Q000196:embryology; D019901:Locus Control Region; D051379:Mice; D012319:RNA Polymerase II / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism*
D014157:Transcription Factors; D005914:Globins; D012319:RNA Polymerase II