Rizzi Nicoletta, Denegri Marco, Chiodi Ilaria, Corioni Margherita, Valgardsdottir Rut, Cobianchi Fabio, Riva Silvano, Biamonti Giuseppe
Istituto di Genetica Molecolare, Consiglio Nazionale delle Ricerche, 27100 Pavia, Italy.
Mol Biol Cell. 2004 Feb;15(2):543-51. doi: 10.1091/mbc.e03-07-0487. Epub 2003 Nov 14.
Heat shock triggers the assembly of nuclear stress bodies that contain heat shock factor 1 and a subset of RNA processing factors. These structures are formed on the pericentromeric heterochromatic regions of specific human chromosomes, among which chromosome 9. In this article we show that these heterochromatic domains are characterized by an epigenetic status typical of euchromatic regions. Similarly to transcriptionally competent portions of the genome, stress bodies are, in fact, enriched in acetylated histone H4. Acetylation peaks at 6 h of recovery from heat shock. Moreover, heterochromatin markers, such as HP1 and histone H3 methylated on lysine 9, are excluded from these nuclear districts. In addition, heat shock triggers the transient accumulation of RNA molecules, heterogeneous in size, containing the subclass of satellite III sequences found in the pericentromeric heterochromatin of chromosome 9. This is the first report of a transcriptional activation of a constitutive heterochromatic portion of the genome in response to stress stimuli.
热休克触发了核应激小体的组装，核应激小体包含热休克因子1和一部分RNA加工因子。这些结构在特定人类染色体的着丝粒周围异染色质区域形成，其中包括9号染色体。在本文中，我们表明这些异染色质结构域的特征是具有常染色质区域典型的表观遗传状态。实际上，与基因组中具有转录活性的部分相似，应激小体富含乙酰化组蛋白H4。乙酰化在热休克恢复6小时时达到峰值。此外，异染色质标记物，如HP1和赖氨酸9位甲基化的组蛋白H3，被排除在这些核区域之外。另外，热休克触发了大小各异的RNA分子的瞬时积累，这些RNA分子包含在9号染色体着丝粒周围异染色质中发现的卫星III序列亚类。这是关于基因组组成型异染色质部分在应激刺激下发生转录激活的首次报道。
