Chromatin remodeling by SWI/SNF results in nucleosome mobilization to preferential positions in the rat osteocalcin gene promoter.
Changes in local chromatin structure accompany transcriptional activation of eukaryotic genes. In vivo these changes in chromatin organization can be catalyzed by ATP-dependent chromatin-remodeling complexes, such as SWI/SNF. These complexes alter the tight wrapping of DNA in the nucleosomes and can facilitate the mobilization of the histone octamer to adjacent DNA segments, leaving promoter regulatory elements exposed for transcription factor binding. To gain understanding of how the activity of SWI/SNF complexes may be modulated by the different DNA sequences within a natural promoter, we have reconstituted nucleosomes containing promoter segments of the transcriptionally active cell type-specific osteocalcin (OC) gene and determined how they affect the directional movements of the nucleosomes. Our results indicate that SWI/SNF complexes induce octamer sliding to preferential positions in the OC promoter, leading to a nucleosomal organization that resembles that described in intact cells expressing the OC gene. Our studies demonstrate that the position of the histone octamer is primarily determined by sequences within the OC promoter that include or exclude nucleosomes. We propose that these sequences are critical components of the regulatory mechanisms that mediate expression of this tissue-specific gene.
Gutiérrez
José
J
Departamento de Bioquimica y Biologia Molecular, Facultad de Ciencias Biologicas, Universidad de Concepcion, Barrio Universitario s/n, Casilla 160-C, Concepcion 4079100, Chile.
Paredes
Roberto
R
Departamento de Bioquimica y Biologia Molecular, Facultad de Ciencias Biologicas, Universidad de Concepcion, Barrio Universitario s/n, Casilla 160-C, Concepcion 4079100, Chile.
Cruzat
Fernando
F
Departamento de Bioquimica y Biologia Molecular, Facultad de Ciencias Biologicas, Universidad de Concepcion, Barrio Universitario s/n, Casilla 160-C, Concepcion 4079100, Chile.
Hill
David A
DA
Department of Cell Biology, University of Massachusetts Medical School, Worcester, Massachusetts 01655.
van Wijnen
Andre J
AJ
Department of Cell Biology, University of Massachusetts Medical School, Worcester, Massachusetts 01655.
Lian
Jane B
JB
Department of Cell Biology, University of Massachusetts Medical School, Worcester, Massachusetts 01655.
Stein
Gary S
GS
Department of Cell Biology, University of Massachusetts Medical School, Worcester, Massachusetts 01655.
Stein
Janet L
JL
Department of Cell Biology, University of Massachusetts Medical School, Worcester, Massachusetts 01655.
Imbalzano
Anthony N
AN
Department of Cell Biology, University of Massachusetts Medical School, Worcester, Massachusetts 01655.
Montecino
Martin
M
Departamento de Bioquimica y Biologia Molecular, Facultad de Ciencias Biologicas, Universidad de Concepcion, Barrio Universitario s/n, Casilla 160-C, Concepcion 4079100, Chile. Electronic address: mmonteci@udec.cl.
D000818:Animals; D045744:Cell Line, Tumor; D042002:Chromatin Assembly and Disassembly / Q000502:physiology*; D002868:Chromosomal Proteins, Non-Histone / Q000737:chemistry* / Q000502:physiology; D005786:Gene Expression Regulation / Q000235:genetics; D009707:Nucleosomes / Q000235:genetics / Q000378:metabolism*; D015675:Osteocalcin / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism*; D011401:Promoter Regions, Genetic / Q000502:physiology*; D051381:Rats; D014157:Transcription Factors / Q000737:chemistry* / Q000502:physiology
D002868:Chromosomal Proteins, Non-Histone; D009707:Nucleosomes; C445179:SWI-SNF-B chromatin-remodeling complex; D014157:Transcription Factors; D015675:Osteocalcin