Dynamic reorganization of chromatin structure and selective DNA demethylation prior to stable enhancer complex formation during differentiation of primary hematopoietic cells in vitro.
In order to gain insights in the true molecular mechanisms involved in cell fate decisions, it is important to study the molecular details of gene activation where such decisions occur, which is at the level of the chromatin structure of individual genes. In the study presented here we addressed this issue and examined the dynamic development of an active chromatin structure at the chicken lysozyme locus during the differentiation of primary myeloid cells from transgenic mouse bone marrow. Using in vivo footprinting we found that stable enhancer complex assembly and high-level gene expression are late events in cell differentiation. However, even before the onset of gene expression and stable transcription factor binding, specific chromatin alterations are observed. This includes changes in DNA topology and the selective demethylation of CpG dinucleotides located in the cores of critical transcription factor binding sites, but not in flanking DNA. These results firmly support the idea that epigenetic programs guiding blood cell differentiation are engraved into the chromatin of lineage-specific genes and that such chromatin changes are implemented before cell lineage specification.
Tagoh
Hiromi
H
Molecular Medicine Unit, University of Leeds, St James's University Hospital, United Kingdom.
Melnik
Svitlana
S
Lefevre
Pascal
P
Chong
Suyinn
S
Riggs
Arthur D
AD
Bonifer
Constanze
C
D000818:Animals; D001483:Base Sequence; D002454:Cell Differentiation; D002645:Chickens; D002843:Chromatin / Q000378:metabolism*; D018899:CpG Islands; D019175:DNA Methylation; D004274:DNA, Recombinant / Q000235:genetics; D004742:Enhancer Elements, Genetic; D018507:Gene Expression Regulation, Developmental; D006410:Hematopoiesis; D006412:Hematopoietic Stem Cells / Q000166:cytology* / Q000378:metabolism*; D051379:Mice; D008822:Mice, Transgenic; D009113:Muramidase / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D015533:Transcriptional Activation
D002843:Chromatin; D004274:DNA, Recombinant; D014157:Transcription Factors; D009113:Muramidase