Stress-induced transcription of satellite III repeats

Abstract

Exposure of mammalian cells to stress induces the activation of heat shock transcription factor 1 (HSF1) and the subsequent transcription of heat shock genes. Activation of the heat shock response also correlates with a rapid relocalization of HSF1 within a few nuclear structures termed nuclear stress granules. These stress-induced structures, which form primarily on the 9q12 region in humans through direct binding of HSF1 to satellite III repeats, do not colocalize with transcription sites of known hsp genes. In this paper, we show that nuclear stress granules correspond to RNA polymerase II transcription factories where satellite III repeats are transcribed into large and stable RNAs that remain associated with the 9q12 region, even throughout mitosis. This work not only reveals the existence of a new major heat-induced transcript in human cells that may play a role in chromatin structure, but also provides evidence for a transcriptional activity within a locus considered so far as heterochromatic and silent.

Transcription of highly repetitive tandemly organized DNA in amphibians and birds: A historical overview and modern concepts

“…A new period began when several groups independently demonstrated transcription of the satellite DNA under stress conditions. 71,72 These examples removed any questions regarding satellite DNA complete transcriptional inactivity.…”

Pericentric and centromeric transcription: a perfect balance required

“…The first indication of the functional importance of satellite transcripts was the discovery that transcription of certain pericentric satellites was induced under cellular stress in human cells (Jolly et al 2004;Rizzi et al 2004). Stress can be induced in cells by exposing them to any condition outside of their optimal growth range; this includes subjecting cells to high temperature (heat shock), heavy metals, hazardous chemicals, ultraviolet radiation, and hyperosmotic or oxidative conditions (Valgardsdottir et al 2008).…”

“…Stress can be induced in cells by exposing them to any condition outside of their optimal growth range; this includes subjecting cells to high temperature (heat shock), heavy metals, hazardous chemicals, ultraviolet radiation, and hyperosmotic or oxidative conditions (Valgardsdottir et al 2008). After human cells are exposed to high temperatures, heat shock factor 1 protein (HSF1) is upregulated and associates with distinct nuclear structures, termed nuclear stress bodies (nSBs), that accumulate on the pericentric regions of chromosomes (Jolly et al 2004). The nSBs recruit RNAPII and the pericentric satellite III is then highly transcribed.…”

Eukaryotic regulatory RNAs: an answer to the ‘genome complexity’ conundrum

“…These Sat III transcripts are transcribed predominantly from the pericentromeric regions of chromosome 9 (9q12 region), and the expression is strongly induced upon heat shock (Jolly et al 2004;Rizzi et al 2004). The Sat III transcripts are transcribed by RNA pol II, are polyadenylated, and vary in size (Jolly and Lakhotia 2006).…”