Project Summary Gene regulation is fundamental for every aspect of human function and errors in this process are key drivers for many diseases, including cancer. Proper gene expression requires a large number of proteins to assemble and function in a highly coordinated manner, but how this is achieved is still not understood. Recent studies revealed that some transcriptional regulators form dynamic high local concentration assemblies termed transcriptional condensates or hubs. These condensates are driven by weak multivalent interactions, which have biophysical properties and regulatory mechanisms distinct from the long-studied ‘lock and key’-type of high-affinity interactions. As such, the discovery of transcriptional condensates offers a new molecular principle to explain how transcription is organized. However, it remains unclear how exactly transcriptional condensates from, how they are regulated and dysregulated, and how they impact gene control during development and in diseases. This is largely due to the lack of experimental strategies to precisely control condensate formation and its properties for functional and mechanistic interrogations. This project uniquely addresses these major gaps by leveraging naturally occurring disease mutations. We discovered a series of oncogenic mutations in a chromatin regulator that promote aberrant formation of transcriptional condensates. These ‘acquired’ condensates strongly correlated with oncogenic gene activation and tumorigenesis, providing one of the first examples linking aberrant condensate formation to human disease. Using these mutations as the stepping-stone, this project aims to develop a more in-depth and broad understanding of transcriptional condensates and establish their dysregulation as a new pathognenic mechanism. Specifically, we will ask three major questions: (1) How do transcriptional condensates form at the molecule level? (2) What are the regulatory functions enabled by transcriptional condensates? (3) Can transcriptional condensates be therapeutically targeted? We will integrate cutting-edge approaches in structural biology, single-molecule imaging, gene regulation, epigenetics, cancer biology, and high-throughput drug discovery to address these questions. Successful completion of this project would offer definitive evidence and mechanistic insights needed to establish a new model of gene control. It also has the potential to transform how we think about and target gene dysregulation in diseases. The ideal experimental system we discovered and extensive expertise of my lab put us in a unique position to embark on this highly ambitious but urgently needed research program.

Project Narrative Gene regulation is fundamental for every aspect of human function, and errors in this process are key drivers for many diseases ranging from developmental disorders to cancer. This project aims to provide a better understanding of gene regulation by elucidating the functions and mechanisms of a newly recognized form of transcriptional assembly. Successful completion of this project would establish a new model of gene control and have the potential to transform how we target gene dysregulation in cancer and other diseases.