Molecular Biology

Activation from Within

+ See all authors and affiliations

Science  15 Jan 2010:
Vol. 327, Issue 5963, pp. 251
DOI: 10.1126/science.327.5963.251-e

The protein complexes that wrap DNA come in two flavors: core histones and variant histones. Although the H2A histone variant MacroH2A1 is known for its role in repressing transcription in the context of X chromosome inactivation, Gamble et al. describe an activating effect of this factor on autosomal gene expression. They have used chromatin immunioprecipitation and genomic tiling arrays (ChIP-chip) to map the distribution of MacroH2A1 in human primary fibroblasts and a breast cancer cell. MacroH2A1 associates with large chromatin domains (greater than 500 kb) with boundaries near transcription start sites; when MacroH2A1 sits within a transcribed region, repression is often the result, but some genes, such as those involved in responding to serum starvation, are instead protected from silencing.

Genes Dev. 24, 21 (2010).

Navigate This Article