Pharmacological Activation of NRF2 by Omaveloxolone Upregulates NRF2-Target Proteins in SMA Type I Human Fibroblasts.

Spinal muscular atrophy (SMA) is caused by loss of SMN protein and is increasingly recognized as a multisystem disorder involving molecular pathology beyond motor neurons. Recently, we identified dysregulated NRF2-KEAP1 signaling in SMA mice. Since NRF2 coordinates transcriptional programs that maintain cellular redox homeostasis and adaptive stress responses, we investigated whether NRF2 signaling is similarly altered in fibroblasts derived from individuals with SMA type I and whether it can be pharmacologically engaged. Compared with control fibroblasts, SMA fibroblasts displayed reduced basal expression of NRF2 target proteins, including NQO1 and xCT (SLC7A11), along with decreased levels of PGC1α. Omaveloxolone (OMAV), a pharmacological NRF2 activator approved for the treatment of Friedreich's ataxia, increased cell viability and upregulated NRF2 target proteins in both control and SMA fibroblasts. Notably, OMAV produced a modest increase in SMN protein abundance and PGC1α levels selectively in SMA cells. Together, these findings support diminished NRF2 pathway activity as a feature of SMA fibroblasts and demonstrate that OMAV activates NRF2 signaling in this human SMA cellular model, consistent with enhanced cytoprotective signaling. These results support further investigation of NRF2 activation, including OMAV, as a potential adjunctive strategy in SMA.