The Arabidopsis hnRNP-Q Protein LIF2 and the PRC1 Subunit LHP1 Function in Concert to Regulate the Transcription of Stress-Responsive Genes

Abstract

LHP1-INTERACTING FACTOR2 (LIF2), a heterogeneous nuclear ribonucleoprotein involved in cell fate and stress responses, interacts with LIKE HETEROCHROMATIN PROTEIN1 (LHP1), a Polycomb Repressive Complex1 subunit. To investigate LIF2-LHP1 functional interplay, we mapped their genome-wide distributions in wild-type,, and backgrounds, under standard and stress conditions. Interestingly, LHP1-targeted regions form local clusters, suggesting an underlying functional organization of the plant genome. Regions targeted by both LIF2 and LHP1 were enriched in stress-responsive genes, the H2A.Z histone variant, and antagonistic histone marks. We identified specific motifs within the targeted regions, including a G-box-like motif, a GAGA motif, and a-box. LIF2 and LHP1 can operate both antagonistically and synergistically. In response to methyl jasmonate treatment, LIF2 was rapidly recruited to chromatin, where it mediated transcriptional gene activation. Thus, LIF2 and LHP1 participate in transcriptional switches in stress-response pathways.

Genome‐wide occupancy of histone H3K27 methyltransferases CURLY LEAF and SWINGER in Arabidopsis seedlings

“…These observations present us questions that warrant future investigation, such as the locus‐specific recruitment of CLF/SWN and their functional interplay in depositing H3K27me3. In terms of locus‐specific recruitment of PcG proteins, this and other recent studies have identified DNA motifs that are enriched in PcG binding sites (Figure g) (Deng et al., ; Molitor et al., ; Xiao et al., ; Zhou et al., ). Future studies are needed to decipher their roles in mediating the genomic targeting of PcG proteins.…”

“…The Telo ‐box motif has been shown very recently to be recognized by the telomere‐repeat factors (TRBs) which then recruit CLF/SWN through direct physical interaction with CLF/SWN (Zhou et al., ). Of note, the two motifs were also previously identified in the genomic binding regions of other PcG proteins, FIE and LHP1 (Deng et al., ; Molitor et al., ; Xiao et al., ; Zhou, Hartwig, James, Schneeberger, & Turck, ).…”

“…In terms of locus-specific recruitment of PcG proteins, this and other recent studies have identified DNA motifs that are enriched in PcG binding sites (Figure 2g) (Deng et al, 2013;Molitor et al, 2016;Xiao et al, 2017;Zhou et al, 2018). Future studies are needed to decipher their roles in mediating the genomic targeting of PcG proteins.…”

Functional characterization of LIKE HETEROCHROMATIN PROTEIN 1 in the moss Physcomitrella patens: its conserved protein interactions in land plants

“…To further investigate conserved mechanisms of LHP1/TFL2 regulation, we looked into additional proteins that could interact with and modulate activity of PpLHP1 in vivo . For this, we referred to recent studies that reported the characterization of an LHP1‐interacting factor, LIF2 a ribonucleoprotein Q (hnRNP‐Q) in Arabidopsis thaliana (Latrasse et al ., ; Molitor et al ., ). LIF2 interacts with LHP1/TFL2 in vitro and in vivo in the nucleus (Latrasse et al ., ).…”

“…LIF2 interacts with LHP1/TFL2 in vitro and in vivo in the nucleus (Latrasse et al ., ). Together these proteins are known to function synergistically to regulate developmental programs and environment signaling pathways by acting as transcriptional switches on common stress‐responsive genes (Molitor et al ., ).…”