BRAT1 Links Integrator and Defective RNA Processing with Neurodegeneration

Mutations in BRAT1, encoding BRCA1-associated ATM activator 1, have been associated with neurodevelopmental and neurodegenerative disorders characterized by heterogeneous phenotypes with varying levels of clinical severity. However, the underlying molecular mechanisms of disease pathology remain poorly understood. Here, we show that BRAT1 is a functional component of the RNA processing protein complex, Integrator. BRAT1 interacts with the INTS9/INTS11 heterodimer, the core Integrator cleavage complex that processes the 3’ ends of various non-coding RNAs and pre-mRNAs, and we find that Integrator integrity and function are disrupted by BRAT1 deletion. In particular, defects in BRAT1 impede proper 3’ end processing of UsnRNAs, snoRNAs, and replication-dependent histone mRNAs, and alter expression of protein-coding genes. Importantly, defects in Integrator integrity and function are also evident in patient-derived cells from BRAT1 related neurological disease. Collectively, these data identify BRAT1 as a functional component of Integrator and link defects in this critical endonuclease complex with hereditary neurodegenerative disease.