SRG3/mBAF155 stabilizes the SWI/SNF-like BAF complex by blocking CHFR mediated ubiquitination and degradation of its major components.

The murine SWI/SNF-like BAF complex is an ATP-dependent chromatin remodeling complex that functions as a transcriptional regulator in cell proliferation, differentiation and development. The SWI/SNF-like BAF complex consists of several components including core subunits such as BRG1, BAF155/SRG3, BAF47/SNF5/INI1, and BAF170. We have previously shown that the interaction between SRG3/mBAF155 and other components of the complex stabilizes them by attenuating their proteasomal degradation. However, it has not been known how the major components of the SWI/SNF-like BAF complex such as BRG1, SNF5, and BAF60a are targeted for the ubiquitination and degradation, and how SRG3/mBAF155 protects them from the degradation process. Here we report that CHFR interacts with BRG1, SNF5, and BAF60a of the SWI/SNF-like BAF complex and ubiquitinates them to target for degradation through a proteasome-mediated pathway, and that SRG3/mBAF155 stabilizes these components by blocking their interaction with CHFR.