Amy Crawford
New York University
Characterization of Immune Gene Priming LncRNA UMLILO and its Interaction with WDR5
The molecular mechanisms underlying trained immunity are poorly understood, but increasing evidence implicates long non-coding RNAs (lncRNAs) in its regulation. The Upstream Master LncRNA of the Inflammatory chemokine LOcus (UMLILO) regulates epigenetic priming of chemokine genes through interactions with the WD repeat-containing protein 5 (WDR5)-Mixed Lineage Leukemia 1 (MLL1) complex. Exposure of monocytes stimulates increased transcription of UMLILO, which acts in cis to recruit the MLL1/WDR5 complex to nearby chemokine gene promoters, where the methylation complex marks the genes for robust transcription in response to future stimuli. Interestingly, replacing UMLILO with another WDR5–interacting lncRNA HOXA transcript at the distal tip (HOTTIP) rescues UMLILO's function in cells.
In this work, we have investigated the structural mechanism by which WDR5 brings these components together using bioinformatics, chemical probing experiments, and in vitro binding assays. Our work reveals that UMLILO adopts a secondary structure conserved across divergent species, that WDR5 binds with nanomolar affinity to UMLILO and interacts with multiple hairpins, and that WDR5 binds each hairpin with nanomolar affinity. Our next goals are to characterize the structure of the lncRNA HOTTIP and similarly identify WDR5 binding sites in our work towards building a synthetic, chimeric lncRNA capable of recruiting the WDR5/MLL1 complex. Overall, this work provides insight into how UMLILIO interacts with WDR5 to exert transcriptional control and serves the overall goal of enhancing our understanding of how lncRNAs regulate gene expression in cells.
The molecular mechanisms underlying trained immunity are poorly understood, but increasing evidence implicates long non-coding RNAs (lncRNAs) in its regulation. The Upstream Master LncRNA of the Inflammatory chemokine LOcus (UMLILO) regulates epigenetic priming of chemokine genes through interactions with the WD repeat-containing protein 5 (WDR5)-Mixed Lineage Leukemia 1 (MLL1) complex. Exposure of monocytes stimulates increased transcription of UMLILO, which acts in cis to recruit the MLL1/WDR5 complex to nearby chemokine gene promoters, where the methylation complex marks the genes for robust transcription in response to future stimuli. Interestingly, replacing UMLILO with another WDR5–interacting lncRNA HOXA transcript at the distal tip (HOTTIP) rescues UMLILO's function in cells.
In this work, we have investigated the structural mechanism by which WDR5 brings these components together using bioinformatics, chemical probing experiments, and in vitro binding assays. Our work reveals that UMLILO adopts a secondary structure conserved across divergent species, that WDR5 binds with nanomolar affinity to UMLILO and interacts with multiple hairpins, and that WDR5 binds each hairpin with nanomolar affinity. Our next goals are to characterize the structure of the lncRNA HOTTIP and similarly identify WDR5 binding sites in our work towards building a synthetic, chimeric lncRNA capable of recruiting the WDR5/MLL1 complex. Overall, this work provides insight into how UMLILIO interacts with WDR5 to exert transcriptional control and serves the overall goal of enhancing our understanding of how lncRNAs regulate gene expression in cells.
