A crucial role for the ubiquitously expressed transcription factor Sp1 at early stages of hematopoietic specification.
Mammalian development is regulated by the interplay of tissue-specific and ubiquitously expressed transcription factors, such as Sp1. Sp1 knockout mice die in utero with multiple phenotypic aberrations, but the underlying molecular mechanism of this differentiation failure has been elusive. Here, we have used conditional knockout mice as well as the differentiation of mouse ES cells as a model with which to address this issue. To this end, we examined differentiation potential, global gene expression patterns and Sp1 target regions in Sp1 wild-type and Sp1-deficient cells representing different stages of hematopoiesis. Sp1(-/-) cells progress through most embryonic stages of blood cell development but cannot complete terminal differentiation. This failure to fully differentiate is not seen when Sp1 is knocked out at later developmental stages. For most Sp1 target and non-target genes, gene expression is unaffected by Sp1 inactivation. However, Cdx genes and multiple Hox genes are stage-specific targets of Sp1 and are downregulated at an early stage. As a consequence, expression of genes involved in hematopoietic specification is progressively deregulated. Our work demonstrates that the early absence of active Sp1 sets a cascade in motion that culminates in a failure of terminal hematopoietic differentiation and emphasizes the role of ubiquitously expressed transcription factors for tissue-specific gene regulation. In addition, our global side-by-side analysis of the response of the transcriptional network to perturbation sheds a new light on the regulatory hierarchy of hematopoietic specification.
School of Cancer Sciences, Institute of Biomedical Research, College of Medical and Dental Sciences, University of Birmingham, Birmingham B15 2TT, UK.
Jane
J
Gilmour
School of Cancer Sciences, Institute of Biomedical Research, College of Medical and Dental Sciences, University of Birmingham, Birmingham B15 2TT, UK Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK.
Salam A
SA
Assi
Department of Cell Biology, Erasmus MC, Rotterdam 3015 CN, The Netherlands.
Ulrike
U
Jaegle
Department of Cell Biology, Erasmus MC, Rotterdam 3015 CN, The Netherlands.
Divine
D
Kulu
Department of Cell Biology, Erasmus MC, Rotterdam 3015 CN, The Netherlands.
Harmen
H
van de Werken
Section of Experimental Haematology, Leeds Institute of Molecular Medicine, University of Leeds, Leeds LS9 7TS, UK.
Deborah
D
Clarke
Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK.
David R
DR
Westhead
Department of Cell Biology, Erasmus MC, Rotterdam 3015 CN, The Netherlands j.philipsen@erasmusmc.nl c.bonifer@bham.ac.uk.
Sjaak
S
Philipsen
School of Cancer Sciences, Institute of Biomedical Research, College of Medical and Dental Sciences, University of Birmingham, Birmingham B15 2TT, UK j.philipsen@erasmusmc.nl c.bonifer@bham.ac.uk.
Constanze
C
Bonifer
D000818:Animals; D001854:Bone Marrow Cells / Q000166:cytology; D002454:Cell Differentiation; D019070:Cell Lineage; D053595:Embryonic Stem Cells / Q000166:cytology; D020869:Gene Expression Profiling; D018507:Gene Expression Regulation, Developmental; D053263:Gene Regulatory Networks; D006410:Hematopoiesis; D006412:Hematopoietic Stem Cells / Q000166:cytology*; D008264:Macrophages / Q000166:cytology; D051379:Mice; D018345:Mice, Knockout; D020411:Oligonucleotide Array Sequence Analysis; D010641:Phenotype; D011485:Protein Binding; D016329:Sp1 Transcription Factor / Q000502:physiology*; D013234:Stem Cells / Q000166:cytology
D016329:Sp1 Transcription Factor
Hematopoiesis; Mouse; Sp1 transcription factor; Transcriptional network