Stress-induced activation of heterochromatic transcription.
Constitutive heterochromatin comprising the centromeric and telomeric parts of chromosomes includes DNA marked by high levels of methylation associated with histones modified by repressive marks. These epigenetic modifications silence transcription and ensure stable inheritance of this inert state. Although environmental cues can alter epigenetic marks and lead to modulation of the transcription of genes located in euchromatic parts of the chromosomes, there is no evidence that external stimuli can globally destabilize silencing of constitutive heterochromatin. We have found that heterochromatin-associated silencing in Arabidopsis plants subjected to a particular temperature regime is released in a genome-wide manner. This occurs without alteration of repressive epigenetic modifications and does not involve common epigenetic mechanisms. Such induced release of silencing is mostly transient, and rapid restoration of the silent state occurs without the involvement of factors known to be required for silencing initiation. Thus, our results reveal new regulatory aspects of transcriptional repression in constitutive heterochromatin and open up possibilities to identify the molecular mechanisms involved.
Department of Plant Biology, University of Geneva, Geneva, Switzerland.
Mireille
M
Tittel-Elmer
Etienne
E
Bucher
Larissa
L
Broger
Olivier
O
Mathieu
Jerzy
J
Paszkowski
Isabelle
I
Vaillant
D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development; D003080:Cold Temperature; D020869:Gene Expression Profiling; D005966:Glucuronidase / Q000235:genetics / Q000378:metabolism; D006570:Heterochromatin / Q000235:genetics*; D006657:Histones / Q000378:metabolism; D008239:Lysine / Q000378:metabolism; D008745:Methylation / Q000187:drug effects; D020411:Oligonucleotide Array Sequence Analysis; D030821:Plants, Genetically Modified; D020133:Reverse Transcriptase Polymerase Chain Reaction; D036226:Seedlings / Q000235:genetics / Q000254:growth & development; D012965:Sodium Chloride / Q000494:pharmacology; D013312:Stress, Physiological; D013696:Temperature; D013997:Time Factors; D014158:Transcription, Genetic / Q000235:genetics*; D015533:Transcriptional Activation / Q000187:drug effects
D006570:Heterochromatin; D006657:Histones; D012965:Sodium Chloride; D005966:Glucuronidase; D008239:Lysine