Transcription-regulating long non-coding RNAs (lncRNAs) have the potential to control the site-specific expression of thousands of target genes. Previously, we showed that Evf2, the first described ultraconserved lncRNA, increases the association of transcriptional activators (DLX homeodomain proteins) with key DNA enhancers but represses gene expression. In this report, mass spectrometry shows that the Evf2-DLX1 ribonucleoprotein (RNP) contains the SWI/SNFrelated chromatin remodelers Brahma-related gene 1 (BRG1, SMARCA4) and Brahma-associated factor (BAF170, SMARCC2) in the developing mouse forebrain. Evf2 RNA colocalizes with BRG1 in nuclear clouds and increases BRG1 association with key DNA regulatory enhancers in the developing forebrain. While BRG1 directly interacts with DLX1 and Evf2 through distinct binding sites, Evf2 directly inhibits BRG1 ATPase and chromatin remodeling activities. In vitro studies show that both RNA-BRG1 binding and RNA inhibition of BRG1 ATPase/remodeling activity are promiscuous, suggesting that context is a crucial factor in RNAdependent chromatin remodeling inhibition. Together, these experiments support a model in which RNAs convert an active enhancer to a repressed enhancer by directly inhibiting chromatin remodeling activity, and address the apparent paradox of RNAmediated stabilization of transcriptional activators at enhancers with a repressive outcome. The importance of BRG1/RNA and BRG1/homeodomain interactions in neurodevelopmental disorders is underscored by the finding that mutations in Coffin-Siris syndrome, a human intellectual disability disorder, localize to the BRG1 RNAbinding and DLX1-binding domains.
Gene regulation requires selective targeting of DNA regulatory enhancers over megabase distances. Here we show that Evf2, a cloud-forming Dlx5/6 ultraconserved enhancer (UCE) lncRNA, simultaneously localizes to activated (Umad1, 1.6 Mb distant) and repressed (Akr1b8, 27 Mb distant) chr6 target genes, precisely regulating UCE-gene distances and cohesin binding in mouse embryonic forebrain GABAergic interneurons (INs). Transgene expression of Evf2 activates Lsm8 (12 Mb distant) but fails to repress Akr1b8, supporting trans activation and long-range cis repression. Through both short-range (Dlx6 antisense) and long-range (Akr1b8) repression, the Evf2-5'UCE links homeodomain and mevalonate pathway-regulated enhancers to IN diversity. The Evf2-3' end is required for long-range activation but dispensable for RNA cloud localization, functionally dividing the RNA into 3'-activator and 5'UCE repressor and targeting regions. Together, these results support that Evf2 selectively regulates UCE interactions with multi-megabase distant genes through complex effects on chromosome topology, linking lncRNA-dependent topological and transcriptional control with interneuron diversity and seizure susceptibility.
The Evf2 long non-coding RNA directs Dlx5/6 ultraconserved enhancer(UCE)-intrachromosomal interactions, regulating genes across a 27Mb region on chr6 in mouse developing forebrain. Here, we show that Evf2 long-range gene repression occurs through multi-step mechanisms involving the transcription factor Sox2. Evf2 directly interacts with Sox2, antagonizing Sox2 activation of Dlx5/6UCE, and recruits Sox2 to the Dlx5/6eii shadow enhancer and key Dlx5/6UCE interaction sites. Sox2 directly interacts with Dlx1 and Smarca4, as part of the Evf2 ribonucleoprotein complex, forming spherical subnuclear domains (protein pools, PPs). Evf2 targets Sox2 PPs to one long-range repressed target gene (Rbm28), at the expense of another (Akr1b8).Evf2 and Sox2 shift Dlx5/6UCE interactions towards Rbm28, linking Evf2/Sox2 co-regulated topological control and gene repression. We propose a model that distinguishes Evf2 gene repression mechanisms at Rbm28 (Dlx5/6UCE position) and Akr1b8 (limited Sox2 availability). Genome-wide control of RNPs (Sox2, Dlx and Smarca4) shows that co-recruitment influences Sox2 DNA binding. Together, these data suggest that Evf2 organizes a Sox2 PP subnuclear domain, and through Sox2-RNP sequestration and recruitment, regulates chr6 long-range UCE targeting and activity with genome-wide consequences.
Precise regulation of gene expression networks requires the selective targeting of DNA enhancers. The Evf2 long non-coding RNA regulates Dlx5/6 ultraconserved enhancer(UCE) interactions with long-range target genes, controlling gene expression over a 27Mb region in mouse developing forebrain. Here, we show that Evf2 long range gene repression occurs through multi-step mechanisms involving the transcription factor Sox2, a component of the Evf2 ribonucleoprotein complex (RNP). Evf2 directly interacts with Sox2, antagonizing Sox2-dependent Dlx5/6UCE activation. Evf2 regulates Sox2 binding at key sites, including the Dlx5/6eii shadow enhancer and Dlx5/6UCE interaction sites. Evf2 differentially targets RNP-associated Sox2 protein pools (PPs), redirecting Sox2-PPs to one repressed gene at the expense of the other. Co-regulation of Dlx5/6UCEintrachromosomal interactions by Evf2 and Sox2 reveals a role for Sox2 in chromosome topology. We propose that RNA organizes RNPs in a subnuclear domain, regulating both long-range UCE targeting and activity through Sox2-RNP sequestration and recruitment.
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