Work in the last decade from many labs has underlined the critical importance of RNA-mediated cellular
pathways, and clear connections of specific RNAs to human health. RNAs are increasingly viewed both as
appealing therapeutic targets, and as therapeutic agents themselves. We hypothesize that obtaining a
deeper and broader understanding about how ligands interact with the many RNA species of the cell will
provide important new insights into RNA networks and functions, provide new understanding of how current
drugs cause cellular toxicity, and lend novel insights into improving RNA therapies. We are convinced that the
analysis of RNA interactions transcriptome-wide is essential to future biomedicine. Unfortunately, methods for
assessing RNA interactions directly in the cell lag well behind those for protein and proteome analysis.
Recent work from this laboratory has established numerous new molecular tools for analysis of
biologically and clinically relevant RNAs. We developed the first high-yield reaction strategy for functionalizing
RNA 2'-OH groups, establishing broad utility of acylimidazole reagents. We designed the cell-permeable and
broadly used structure-mapping reagents NAI and NAI-N3 - now commercially available - and applying them
with RNA Seq, we mapped folded structures of 16000 mRNAs in mammalian cells. We developed rapid and
simple chemical approaches for functionalizing RNA with fluorescent labels, biotin, hydrophobic groups,
crosslinkers, and caging groups. Further, we designed strategies for labeling RNA either broadly or at specific
sites. Unlike recent enzymatic approaches for RNA labeling, our methods require no engineered structure or
sequence, and thus can be employed rapidly and easily with native RNAs of any origin or length.
The proposed project will consolidate our RNA work into a broad program that will develop a new set of
RNA-reactive reagents and methods, and will apply them to provide specific, quantitative information about
ligand interactions with the transcriptome. We will develop first-in-class methods for functionalizing native
RNAs at specific sites, and novel strategies for controlling RNAs with red light. Combining our reactive acyl
tools and methods with next-gen sequencing, we will pinpoint and quantify ligand binding sites in the whole
transcriptome. These methodologies, together termed Reactivity-Based RNA Profiling (RBRP), will be
applied to analyzing off-target RNA binding by known small-molecule drugs with clinically limiting toxicity, to
profiling RNA interactions of endogenous secondary metabolites, and to the analysis of how modified bases
in next-generation mRNA vaccines and therapeutics affect their structures and interactions in the cell. This
work is significant because it seeks answers to system-wide clinically-relevant questions regarding RNA
interactions. Further, it develops the 2'-OH group as a nearly universal handle for manipulation, conjugation,
and study of RNAs, introducing enabling molecular technologies that will broadly benefit researchers in the
fields of RNA biology and contribute to improving future RNA therapies.