Amyotrophic Lateral Sclerosis-associated Mutants of SOD1 Modulate miRNA Biogenesis through Aberrant Interactions with Exportin 5

ABSTRACT: Mutations in SOD1 (Superoxide Dismutase 1) gene are associated with amyotrophic lateral sclerosis (ALS), a fatal neurodegenerative disease. By employing ascorbate peroxidase (APEX)-based proximity labeling, coupled with LC-MS/MS analysis, we uncovered 37 and 28 proteins exhibiting higher abundance in the proximity proteomes of SOD1G85R and SOD1G93A, respectively, than that of the wild-type SOD1. Immunoprecipitation followed by western blot analysis confirmed the preferential binding of one of these proteins, exportin 5 (XPO5), toward the two mutants of SOD1 over its wild-type counterpart. In line with the established function of XPO5 in pre-miRNA transport, we observed diminished nucleocytoplasmic transport of pre-miRNAs in cells with ectopic expression of the two SOD1 mutants over those expressing the wild-type counterpart. On the other hand, RT-qPCR results revealed significant elevations in mature miRNA in cells expressing the two SOD1 mutants, which are attributed to diminished inhibitory effect of XPO5 on Dicer-mediated cleavage of pre-miRNA to mature miRNA. Together, our chemoproteomic approach led to the revelation of a novel mechanism through which ALS-associated mutants of SOD1 perturb miRNA biogenesis, i.e., through aberrant binding toward XPO5.

INSTRUMENT(S): Q Exactive

ORGANISM(S): Homo Sapiens (human) Mus Musculus (mouse)

TISSUE(S): Permanent Cell Line Cell

SUBMITTER: Xingyuan Chen  

LAB HEAD: YINSHENG WANG

PROVIDER: PXD035452 | Pride | 2024-01-26

REPOSITORIES: Pride