Snf2 proteins are a large family of proteins present across all eukaryotes that have many roles in remodelling chromatin to regulate gene expression. Analysis of cancer tumour sequencing datasets has shown that several Snf2 proteins are included in the top 200 tumour suppressor genes, particularly SMARCA4, the Snf2 ATPase subunit of the human SWI/SNF complex. Most mutations in Snf2 proteins found in tumours are missense mutations; however, the mode of action through which these mutations may cause disease remains uncertain. Here, an analysis of sequencing data was performed to uncover particular sites which are both functionally important for enzyme activity and frequently mutated in cancer. Mutations were generated in recombinant Snf2 proteins and shown to affect the biochemical activity of proteins and alter their structure to be inactive. A point mutation was generated in SMARCA4 in mouse embryonic stem cells. This mutation did not affect cell viability but reduced chromatin accessibility in a manner similar to SMARCA4 inhibitors. Additionally, a heterozygous mutant affected chromatin accessibility similarly to a homozygous mutant, providing evidence for SMARCA4 missense mutations having dominant-negative phenotypes.
|Date of Award||2022|
|Supervisor||Tom Owen-Hughes (Supervisor)|