Hey, DNA, get over here

Active genes sidle up to Cajal bodies with help from actin, Dundr et al. report. The study is the first to show directed movement of mammalian genes that are being transcribed.

Interphase chromosomes jiggle, but they usually remain within so-called territories. Particular DNA segments, however, can travel substantial distances. One situation that might involve DNA movement is the liaison between active genes and Cajal bodies, which harbor small nuclear RNAs (snRNAs) for splicing. Cajal bodies often show up near working genes for snRNA and histone proteins, although researchers didn't know whether Cajal bodies form near these genes or whether the partners move toward each other.

To find out, Dundr et al. inserted into HeLa cells an artificial chromosome carrying 16 copies of an snRNA gene. The team tracked...