Epigenetics

Higher-order structure in pericentric heterochromatin involves a distinct pattern of histone modification and an RNA component.Maison, C. et al. Nature Genet. 30, 329–334 (2002) | PubMed |

The non-coding Air RNA is required for silencing autosomal imprinted genes.Sleutels, F. et al. Nature 415, 810–813 (2002)

Epigenetic regulation of gene expression is mainly achieved through modulation of chromatin states. Centromeric heterochromatin is essential for centromere function in yeast and mammals and accounts for transcriptional silencing. By selectively blocking hypoacetylation and methylation of histones in the mammalian centromeric region, Maison and colleagues found that these two types of modification can occur independently, on different histones. They also find that the association of an RNA molecule with the methylated histones is required for the accumulation of HP1 protein in this complex, which leads to stabilization of heterochromatin. The second paper, by Sleutels et al., reports that a non-coding RNA molecule is also involved in imprinting. The Air RNA is required for silencing of the Igf2r/Slc22a2/Slc22a3 gene cluster on the paternal chromosome — repression of this cluster correlates with Air RNA expression.

Bioinformatics

Computational detection and location of transcriptional start sites in mammalian genomic DNA.Down, T. A. et al. Genome Res. 12, 458–461 (2002)

The promoters of complex species frequently contain several transcription start sites (TSSs), which are difficult to detect computationally because of the diffuse, complex structure of eukaryotic promoters. Here, Down and Hubbard describe a new bioinformatics program, Eponine, which they use in a novel approach to detect TSSs. They report that a TATA box in combination with (C+G)-rich flanking sequence — and not a TATA box alone — gives the best indication of the presence of a TSS.

Human genetics

A genome-wide linkage screen for relative hand skill in sibling pairs.Francks, C. et al. Am. J. Hum. Genet. 70, 800–805 (2002)

This paper reports the first genome-wide screen for a measure that is related to handedness in humans and the identification of a putative quantitative trait locus (QTL) on chromosome 2p11.2–12 that influences relative hand skill in a sample of 195 dyslexic sibling pairs. However, Francks et al. found that this QTL was not significantly associated with relative hand skill in a second dyslexic sibling sample, indicating that this trait has a complex genetic aetiology.