The small-molecule flunarizine in spinal muscular atrophy patient fibroblasts impacts on the Gemin components of the SMN complex and RNA-binding proteins relevant to motor neuron diseases

The deficiency of Survival motor neuron (SMN) protein causes the motor neuron disease spinal muscular atrophy (SMA). One of the cellular hallmarks of motor neuron diseases is the reduction in number of nuclear bodies (NBs) positive for the SMN protein. Owing to its ubiquitous expression, the consequences of SMN reduction can be studied in SMA patient fibroblasts. In previous studies, we described the beneficial effects of flunarizine on SMN-positive NBs both in fibroblasts of SMA patients and in spinal motor neurons of an SMA mouse model. Given that nuclear bodies are involved in RNA metabolism, here the goals are to make a proof-of-concept that genes modulated by flunarizine at the RNA levels can be identified and confirmed at the protein levels in SMA patient fibroblasts. Indeed, RNA-Seq analysis reveals that TXNIP is the most reduced by a 4-hr flunarizine treatment of SMA patient fibroblasts. This result is confirmed by RT-qPCR. Moreover, immunoblot analyses also shows a marked reduction of TXNIP at the protein levels in flunarizine-treated SMA fibroblasts. Examination of components of the SMN complex and RNA molecules modulated by flunarizine in immortalized type I SMA patient fibroblasts *** Submitter declares raw files were lost. ***