Differential Interactions of the Autonomous Pathway RRM Proteins and Chromatin Regulators in the Silencing of Arabidopsis Targets

Abstract

We have recently shown that two proteins containing RRM-type RNA-binding domains, FCA and FPA, originally identified through their role in flowering time control in Arabidopsis, silence transposons and other repeated sequences in the Arabidopsis genome. In flowering control, FCA and FPA function in the autonomous pathway with conserved chromatin regulators, the histone demethylase FLD and the MSI1-homologue FVE, a conserved WD-repeat protein found in many chromatin complexes. Here, we investigate how the RRM proteins interact genetically with these chromatin regulators at a range of loci in the Arabidopsis genome. We also investigate their interaction with the DNA methylation pathway. In several cases the RRM protein activity at least partially required a chromatin regulator to effect silencing. However, the interactions of the autonomous pathway components differed at each target analysed, most likely determined by certain properties of the target loci and/or other silencing pathways. We speculate that the RNA-binding proteins FCA and FPA function as part of a transcriptome surveillance mechanism linking RNA recognition with chromatin silencing mechanisms.

The WD40-Repeat Proteins NFC101 and NFC102 Regulate Different Aspects of Maize Development through Chromatin Modification

“…nfc101/nfc102 and TEs FVE and MSI5 are required for silencing of some Arabidopsis TEs and genomic repeats (Bäurle and Dean, 2008;Gu et al, 2011). Accordingly, we assessed whether the transcript level of maize TEs was affected in nfc101/nfc102 downregulation lines.…”

“…FVE activity is not limited to flowering regulation. Indeed, FVE is involved in coldinducible gene expression (Kim et al, 2004) and modulates silencing of transposable elements (TEs) and repeats, acting as an effector of the RNA-directed DNA methylation (RdDM) pathway (Bäurle and Dean, 2008;Gu et al, 2011).…”

Establishment of the Winter-Annual Growth Habit viaFRIGIDA-Mediated Histone Methylation atFLOWERING LOCUS CinArabidopsis

“…We have found that FRI does not disrupt the recruitment of FLD (or FLD-containing corepressor complex) to FLC chromatin but may partially disrupt FLD function. Because the AP genes FCA and FPA mainly function through FLD to repress FLC expression Baurle and Dean, 2008), a functional FRI may also disrupt the FLC repression mediated by these two genes. Taken together, our study suggests that FRI may play a dual role in the H3K4 trimethylation of FLC chromatin, namely, enriching an H3K4 methyltransferase complex and compromising H3K4 demethylation at FLC, to upregulate FLC expression and thus establish the winter-annual growth habit.…”

“…Arabidopsis thaliana fld-1, fld-3 , fca-9 (Baurle and Dean, 2008), and FRI-Col (Lee et al, 1994) were described previously. The wdr5b mutant was isolated from the Versailles transformant collection (Samson et al, 2002).…”

“…FLD, a plant homolog of the human Lysine-Specific Demethylase1 (LSD1) that has been found in histone deacetylase (HDAC) corepressor complexes (Shi et al, 2004;Lee et al, 2006), is involved in H3K4 demethylation and histone deacetylation in FLC Jiang et al, 2007;Liu et al, 2007). Both FCA and FPA, encoding putative RNA-Recognition Motif-type RNA binding proteins, largely act through FLD to repress FLC expression Baurle and Dean, 2008). FVE, a retinoblastomaassociated protein, is partly involved in histone deacetylation of FLC chromatin (Ausin et al, 2004).…”