Stress granules containing HSF1 (red) produce satellite III transcripts (green).
These inactive DNA stretches are binding sites for HSF1, a transcription factor that activates individual heat shock genes and accumulates in nuclear granules after heat shock. These granules were, like HSF1, expected to activate heat shock genes. So their recent localization to heterochromatic satellite III regions, which do not contain the major heat shock genes, was surprising. Jolly now shows that the stress granules activate transcription even in these repeat sequences.
The stress granules on satellite III repeats were found to contain RNA polymerase II and acetylated histones, which together produced large transcripts in response to heat shock. Heat stress has...
