RNAi and heterochromatin in plants and fission yeast / Robert Martienssen.

• Contents: Heterochromatin is composed of transposable elements (TEs) and related repeats -- heterochromatic gene silencing and TE-mediated silencing are related and may be important in large genomes -- tiling microarrays can be used to examine heterochromatic transcripts as well as DNA and histone modification -- small interfering RNA (siRNA) corresponds to transposons and repeats -- in plants TE siRNA depend on DNA methyltransferase MET1 and the SWI/SNF ATPase DDM1 which silence TEs via DNA and histone H3 lysine-9 (H3K9) methylation -- in fission yeast and plants centromeric repeats are transcribed on one strand but rapidly turned over by RNA interference (RNAi) -- RNAi of centromeric transcripts is required for transcriptional silencing of reporter genes -- RNA polymerase II, the Argonaute (RITS) and RNA dependent RNA polymerase (RDRC) complexes are associated with heterochromatin and required for silencing -- H3K9me2 depends on RNAi and on the Rik1-Clr4 complex -- Clr4 is the histone H3K9 dimethyltransferase -- Rik1 resembles both DNA and RNA binding proteins and is required for RNAi along with Clr4 -- LTR retrotransposon silencing depends on histone deacetylation and silences pericentromeric repeats in Arabidopsis in addition to RNAi.

Subject headings

Epigenesis, Genetic.  (MeSH)

Heterochromatin.  (MeSH)

Plants.  (MeSH)

RNA Interference.  (MeSH)

Schizosaccharomyces.  (MeSH)