Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, United States; Medical Scientist Training Program, University of Texas Southwestern Medical Center, Dallas, United States
Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, United States; Harold C Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, Dallas, United States; Hamon Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center, Dallas, United States; Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, United States
NORAD is a conserved long noncoding RNA (lncRNA) that is required for genome stability in mammals. NORAD acts as a negative regulator of PUMILIO (PUM) proteins in the cytoplasm, and we previously showed that loss of NORAD or PUM hyperactivity results in genome instability and premature aging in mice (Kopp et al., 2019). Recently, however, it was reported that NORAD regulates genome stability through an interaction with the RNA binding protein RBMX in the nucleus. Here, we addressed the contributions of NORAD:PUM and NORAD:RBMX interactions to genome maintenance by this lncRNA in human cells. Extensive RNA FISH and fractionation experiments established that NORAD localizes predominantly to the cytoplasm with or without DNA damage. Moreover, genetic rescue experiments demonstrated that PUM binding is required for maintenance of genomic stability by NORAD whereas binding of RBMX is dispensable for this function. These data provide an important foundation for further mechanistic dissection of the NORAD-PUMILIO axis in genome maintenance.
