Project Summary
Chemical genetic approaches are powerfully enabling for biological discovery and therapeutics
development. The identification of mutant alleles that enhance or suppress the activity of chemical probes may
not only validate on-target mechanism but also drive deeper understanding of a small molecule’s binding
interactions, molecular mechanism of action, and downstream biological effects. Recent breakthroughs in
genome editing technologies enable the systematic mutation of endogenous proteins at scale and directly in
cells, opening new research paradigms for chemical genetic approaches. Exploiting these new technologies, our
prior work helped pioneer the development of in situ CRISPR-mutational scanning approaches to systematically
profile protein target(s) sequence-function relationships in their native cellular environment. When leveraged with
chemical biology, these mutations in the target can be exploited as discovery tools to study small molecule
mechanism of action and target biology, allowing us to uncover mechanisms of allosteric regulation, cell
signaling, and cancer vulnerabilities. This chemical genomics platform allows us to unlock the serendipitous
discoveries that both chemical probes and cutting-edge genetic screens can afford. To push the boundaries of
chemical genomics, these approaches and their associated tools will need to be innovated, expanded, and tested
in biologically meaningful systems and contexts that address key questions in the field. Hence, this proposal
aims to significantly broaden the scope and utility of in situ CRISPR-mutational scanning in the context of
highlighting its potential to transform many facets of chemical biology: to (1) interrogate drug-target structure-
function in primary cells, (2) integrate massively parallel single-cell multi-omic readouts of mutant phenotypes,
and (3) illuminate the function, mechanisms, and biology of protein disordered regions as well as (4) multi-subunit
protein complexes. We focus our future studies on (1) androgen receptor, a critical cancer gene, where
integrating high-throughput, direct readouts of transcription factor function will be transformative, and (2)
components involved in targeted protein degradation, where holistically interrogating the ubiquitin-proteasome
system at scale is essential for understanding the whole pathway. Across these aims, the biology and
mechanisms of various protein complexes will be deeply explored by leveraging mutant alleles with cell,
molecular, computational, and structural biology. Altogether, accomplishment of these objectives will advance
research paradigms for chemical genomics and will further illuminate fundamental mechanisms of small
molecule action and protein complex function.