TY  - JOUR
A1  - Berry, Scott
A1  - Rosa, Stefanie
A1  - Howard, Martin
A1  - Buhler, Marc
A1  - Dean, Caroline
T1  - Disruption of an RNA-binding hinge region abolishes LHP1-mediated epigenetic repression
JF  - Genes & Development
N2  - Epigenetic maintenance of gene repression is essential for development. Polycomb complexes are central to this memory, but many aspects of the underlying mechanism remain unclear. LIKE HETEROCHROMATIN PROTEIN 1 (LHP1) binds Polycomb-deposited H3K27me3 and is required for repression of many Polycomb target genes in Arabidopsis. Here we show that LHP1 binds RNA in vitro through the intrinsically disordered hinge region. By independently perturbing the RNA-binding hinge region and H3K27me3 (trimethylation of histone H3 at Lys27) recognition, we found that both facilitate LHP1 localization and H3K27me3 maintenance. Disruption of the RNAbinding hinge region also prevented formation of subnuclear foci, structures potentially important for epigenetic repression.
KW  - chromatin
KW  - epigenetics
KW  - plant biology
KW  - Polycomb
KW  - RNA
Y1  - 2017
U6  - https://doi.org/10.1101/gad.305227.117
SN  - 0890-9369
SN  - 1549-5477
VL  - 31
SP  - 2115
EP  - 2120
PB  - Cold Spring Harbor Laboratory Press
CY  - Cold Spring Harbor, NY
ER  - 
TY  - JOUR
A1  - Ietswaart, Robert
A1  - Rosa, Stefanie
A1  - Wu, Zhe
A1  - Dean, Caroline
A1  - Howard, Martin
T1  - Cell-Size-Dependent Transcription of FLC and Its Antisense Long Non-coding RNA COOLAIR Explain Cell-to-Cell Expression Variation
JF  - Cell systems
N2  - Single-cell quantification of transcription kinetics and variability promotes a mechanistic understanding of gene regulation. Here, using single-molecule RNA fluorescence in situ hybridization and mathematical modeling, we dissect cellular RNA dynamics for Arabidopsis FLOWERING LOCUS C (FLC). FLC expression quantitatively determines flowering time and is regulated by antisense (COOLAIR) transcription. In cells without observable COOLAIR expression, we quantify FLC transcription initiation, elongation, intron processing, and lariat degradation, as well as mRNA release from the locus and degradation. In these heterogeneously sized cells, FLC mRNA number increases linearly with cell size, resulting in a large cell-to-cell variability in transcript level. This variation is accounted for by cell-sizedependent, Poissonian FLC mRNA production, but not by large transcriptional bursts. In COOLAIRexpressing cells, however, antisense transcription increases with cell size and contributes to FLC transcription decreasing with cell size. Our analysis therefore reveals an unexpected role for antisense transcription in modulating the scaling of transcription with cell size.
Y1  - 2017
U6  - https://doi.org/10.1016/j.cels.2017.05.010
SN  - 2405-4712
SN  - 2405-4720
VL  - 4
SP  - 622
EP  - 635
PB  - Cell Press
CY  - Cambridge
ER  -