RESEARCH
The chemical structures of metabolites are repositories of biological information. How this information is encoded, interpreted, and enacted remains an uncharted dimension in human health. As our most structurally complex metabolite, cholesterol acts as a substrate for a repertoire of signaling molecules that coordinate processes in development, neurobiology, and the immune response. Accordingly, dysregulated activity of cholesterol and its metabolites lies at the heart of diseases such as cancer, neurodegeneration, and immune system disorders. Our lab uses a combination of synthetic, biochemical, and genetic tools to define how specific cholesterol metabolites wire and re-wire cellular pathways, with the ultimate goal of translating their structural code into new small molecule therapeutics.
A proteome-wide map of cholesterol metabolite recognition
Proteins have evolved precise binding pockets, surface topologies, and membrane preferences to sense and respond to cholesterol and its metabolites. Yet how cells interpret these binding events is a function not only of affinity, but also of protein expression levels, spatiotemporal distributions, and combinatorial interactions. Uniquely empowered by chemical synthesis, we create precise chemical tools for quantitative, unbiased, live-cell analysis of cholesterol metabolite binding at the proteome-wide level. Our studies have revealed cholesterol metabolite control over a cassette of known and novel regulatory proteins (e.g. the orphan receptor TMEM97) and a quantitative index of targets that underlie cholesterol metabolite-sensitive phenotypes. Using our custom library of chemoproteomics probes, we are: (1) developing new approaches for data-driven analysis and prediction of global cholesterol metabolite binding sites, and (2) pairing our analysis with transcriptional profiling to link target engagement to gene expression in specific cellular contexts. Our studies aim to define the three-dimensional binding interfaces and proteome-wide signaling mechanisms involved in cholesterol metabolite control, providing a direct path to target the interactions that drive disease.
A proteome-wide map of 20(S)-hydroxycholesterol targets in live cell membranes.
Oxysterol-dependent protein colocalization in specialized cell membranes
A cellular portrait of cholesterol-dependent membrane landscapes
The cholesterol content of membranes determines fundamental biophysical properties such as curvature, thickness, permeability, and stiffness. As a result, cells have evolved mechanisms to fine-tune cholesterol composition in different membranes, enabling them to sort and sequester proteins, communicate between organelles, and choreograph vesicular transport processes. This unique mode of regulation drives a spectrum of cellular activities and is strategically hijacked in disease states such as viral infection and tumor metastasis. To understand how cholesterol and its metabolites direct membrane topologies and signaling events, our lab leverages unique chemical tools to visualize and manipulate cellular cholesterol content. We pair these tools with techniques in cellular fluorescence microscopy, membrane biophysics, and quantitative protein biochemistry to define the effects of cholesterol metabolites on dynamic membrane microenvironments. Our ultimate goal is to define therapeutic opportunities in cholesterol-sensitive biophysical events and leverage them to tackle diseases like Alzheimer’s, cancer, and autoimmunity.
Cholesterol metabolites in health & disease networks
Cells exploit information in the structure of cholesterol and its metabolites to control gene expression programs and intercellular communication. To pinpoint precisely where cholesterol metabolites exert their influence, we use a combination of chemical, genetic, and computational technologies that integrate molecular and systems analysis of signaling networks. Specifically, we are elucidating the details of cholesterol metabolite control over signal transduction processes in the oncogenic Hedgehog pathway, where disruption of cholesterol binding and membrane occupancy leads to multiple forms of cancer; in virus infection, where hijacking of membrane cholesterol organizes various stages of infectivity and replication; and in neurological disease, where perturbation of intracellular cholesterol distribution influences phenomena from conductivity to amyloid formation. Together, we aim to identify new mechanisms of molecular control by cholesterol and its metabolites and to repurpose their activities for therapeutic design.
Multiple points of cholesterol regulation in the Hedgehog signaling pathway