Title

Maintenance of open chromatin and selective genomic occupancy at the cell cycle-regulated histone H4 promoter during differentiation of HL-60 promyelocytic leukemia cells

GSBS Program

Biochemistry & Molecular Pharmacology

UMMS Affiliation

Graduate School of Biomedical Sciences; Department of Cell Biology

Date

1-31-2003

Document Type

Article

Medical Subject Headings

Acetylation; Cell Cycle; Cell Differentiation; Cell Lineage; Chromatin; Deoxyribonuclease I; Down-Regulation; Gene Expression Regulation; HL-60 Cells; Histones; Humans; Macrophages; Micrococcal Nuclease; Monocytes; Nucleosomes; Promoter Regions (Genetics); Proteins; Regulatory Sequences, Nucleic Acid; Repressor Proteins; Restriction Mapping; Transcription Factors

Disciplines

Life Sciences | Medicine and Health Sciences

Abstract

During the shutdown of proliferation and onset of differentiation of HL-60 promyelocytic leukemia cells, expression of the cell cycle-dependent histone genes is downregulated at the level of transcription. To address the mechanism by which this regulation occurs, we examined the chromatin structure of the histone H4/n (FO108, H4FN) gene locus. Micrococcal nuclease, DNase I, and restriction enzymes show similar cleavage sites and levels of sensitivity at the H4/n locus in both proliferating and differentiated HL-60 cells. In contrast, differentiation-related activation of the cyclin-dependent kinase inhibitor p21(cip1/WAF1) gene is accompanied by increased nuclease hypersensitivity. Chromatin immunoprecipitation assays of the H4/n gene reveal that acetylated histones H3 and H4 are maintained at the same levels in proliferating and postproliferative cells. Thus, the chromatin of the H4/n locus remains in an open state even after transcription ceases. Using ligation-mediated PCR to visualize genomic DNase I footprints at single-nucleotide resolution, we find that protein occupancy at the site II cell cycle element is selectively diminished in differentiated cells while the site I element remains occupied. Decreased occupancy of site II is reflected by loss of the site II binding protein HiNF-P. We conclude that H4 gene transcription during differentiation is downregulated by modulating protein interaction at the site II cell cycle element and that retention of an open chromatin conformation may be associated with site I occupancy.

Rights and Permissions

Citation: Mol Cell Biol. 2003 Feb;23(4):1460-9.

Related Resources

Link to article in PubMed