The spinal muscular atrophy (SMA) protein, survival motor neuron (SMN), functions in the biogenesis of small nuclear ribonucleoproteins (snRNPs). SMN has also been implicated in tissue-specific functions; however, it remains unclear which of these is important for the etiology of SMA. . Smn null mutants display larval lethality and show significant locomotion defects as well as reductions in minor-class spliceosomal snRNAs. Despite these reductions, we found no appreciable defects in the splicing of mRNAs containing minor-class introns. Transgenic expression of low levels of either wild-type or an SMA patient-derived form of SMN rescued the larval lethality and locomotor defects; however, snRNA levels were not restored. Thus, the snRNP biogenesis function of SMN is not a major contributor to the phenotype of . Smn null mutants. These findings have major implications for SMA etiology because they show that SMN@s role in snRNP biogenesis can be uncoupled from the organismal viability and locomotor defects.
Praveen, K., Wen, Y., & Matera, A. G. (2012). A Drosophila Model of Spinal Muscular Atrophy Uncouples snRNP Biogenesis Functions of Survival Motor Neuron from Locomotion and Viability Defects. Cell Reports, 1(6), 624–631. https://doi.org/10.1016/j.celrep.2012.05.014