The role of EKLF in human beta-globin gene competition.
We have investigated the role of erythroid Kruppel-like factor (EKLF) in expression of the human beta-globin genes in compound EKLF knockout/human beta-locus transgenic mice. EKLF affects only the adult mouse beta-globin genes in homozygous knockout mice; heterozygous mice are unaffected. Here we show that EKLF knockout mice express the human epsilon and gamma-globin genes normally in embryonic red cells. However, fetal liver erythropoiesis, which is marked by a period of gamma- and beta-gene competition in which the genes are alternately transcribed, exhibits an altered ratio of gamma- to beta-gene transcription. EKLF heterozygous fetal livers display a decrease in the number of transcriptionally active beta genes with a reciprocal increase in the number of transcriptionally active gamma genes. beta-Gene transcription is absent in homozygous knockout fetuses with coincident changes in chromatin structure at the beta promoter. There is a further increase in the number of transcriptionally active gamma genes and accompanying gamma gene promoter chromatin alterations. These results indicate that EKLF plays a major role in gamma- and beta-gene competition and suggest that EKLF is important in stabilizing the interaction between the Locus Control Region and the beta-globin gene. In addition, these findings provide further evidence that developmental modulation of globin gene expression within individual cells is accomplished by altering the frequency and/or duration of transcriptional periods of a gene rather than changing the rate of transcription.
Wijgerde
M
M
Medical Genetics Center Department of Cell Biology and Genetics, Erasmus University Rotterdam, The Netherlands.
Gribnau
J
J
Trimborn
T
T
Nuez
B
B
Philipsen
S
S
Grosveld
F
F
Fraser
P
P
D000818:Animals; D002843:Chromatin / Q000648:ultrastructure; D004247:DNA / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics*; D003850:Deoxyribonuclease I / Q000378:metabolism; D004920:Erythropoiesis / Q000235:genetics*; D018507:Gene Expression Regulation, Developmental; D005812:Genes, Switch; D005914:Globins / Q000096:biosynthesis / Q000235:genetics*; D006579:Heterozygote; D006720:Homozygote; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D051741:Kruppel-Like Transcription Factors; D008099:Liver / Q000196:embryology / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D008822:Mice, Transgenic; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000302:isolation & purification; D013997:Time Factors; D014157:Transcription Factors / Q000235:genetics*
D002843:Chromatin; D004268:DNA-Binding Proteins; D051741:Kruppel-Like Transcription Factors; D012333:RNA, Messenger; D014157:Transcription Factors; C080774:erythroid Kruppel-like factor; D005914:Globins; D004247:DNA; D003850:Deoxyribonuclease I