Structure-activity relationships governing mammalian SWI/SNF chromatin remodeling activity as a function of chromatin state

PROJECT SUMMARY Recent whole-exome sequencing studies in human cancer and neurodevelopmental disorders have unmasked frequent mutations in genes encoding chromatin regulatory proteins. Specifically, genes encoding subunits of the mammalian SWI/SNF ATP-dependent chromatin remodeling complexes (also called mSWI/SNF or BAF complexes) are perturbed in over 20% of malignancies, underscoring their critical roles in the maintenance of timely and appropriate gene expression. The mechanisms by which mSWI/SNF family complexes are targeted on chromatin and the features of the histone landscape that govern their activities remain unknown. Indeed, a systematic evaluation defining the contributions of specific histone landscape features to canonical BAF, PBAF, and non-canonical BAF complex targeting and activity would represent a significant advancement in the field at- large. Here we aim to: (1) Determine the genome-wide targeting of distinct, final-form mSWI/SNF complexes in human cells and the impact of select cancer-associated complex perturbations; (2) Define the in vitro nucleosome remodeling and ATPase activities of endogenously-purified mSWI/SNF subcomplexes, BAF, PBAF, and ncBAF, in wild-type (WT) and mutant states; and (3) Determine the impact of core histone variants and histone tail modifications on mSWI/SNF complex nucleosome binding and activity. Taken together, successful completion of these aims centered at the intersection of biochemistry, epigenetics, and cancer biology, will constitute a highly timely series of advances in the field of chromatin biology, and will contribute important knowledge regarding the mechanism of targeting of mSWI/SNF complexes across a range of both normal and oncogenic states. Given that a major impediment to the development of on-target modulatory agents of mSWI/SNF complexes lies in the lack of biological understanding of complex-specific targeting and functional regulation, the results of this proposal are likely to provide the basis for new approaches toward targeted disruption of mSWI/SNF-chromatin interactions.