Design, Optimization, and Study of Small Molecules That Target Tau Pre-mRNA and Affect Splicing

Approximately
95% of human genes are alternatively spliced, and
aberrant splicing events can cause disease. One pre-mRNA that is alternatively
spliced and linked to neurodegenerative diseases is tau (microtubule-associated
protein tau), which can cause frontotemporal dementia and parkinsonism
linked to chromosome 17 (FTDP-17) and can contribute to Alzheimer’s
disease. Here, we describe the design of structure-specific lead small
molecules that directly target tau pre-mRNA from sequence. This was
followed by hit expansion and analogue synthesis to further improve
upon these initial lead molecules. The emergent compounds were assessed
for functional activity in a battery of assays, including binding
assays and an assay that mimics molecular recognition of tau pre-mRNA
by a U1 small nuclear ribonucleoprotein (snRNP) splicing factor. Compounds
that emerged from these studies had enhanced potency and selectivity
for the target RNA relative to the initial hits, while also having
significantly improved drug-like properties. The compounds are shown
to directly target tau pre-mRNA in cells, via chemical cross-linking
and isolation by pull-down target profiling, and to rescue disease-relevant
splicing of tau pre-mRNA in a variety of cellular systems, including
primary neurons. More broadly, this study shows that lead, structure-specific
compounds can be designed from sequence and then further optimized
for their physicochemical properties while at the same time enhancing
their activity.