Development of secretome-based therapy by motor neuron modulation of miRNA-124 in ALS mouse models

Abstract

Amyotrophic Lateral Sclerosis (ALS) is a fatal disease characterized by the degeneration of upper (cortical) and lower (spinal cord, SC) motor neurons (MNs) and aberrancy of glial cells. Results from our group point to a close connection between increased levels of miRNA-124 and the acquisition of pathological characteristics in MNs, astrocytes and microglia in ALS. Our main aim was to validate if the downregulation of the elevated levels of miR-124 in hSOD1G93A (mSOD1) MNs toward normal levels was preventive over neurodegeneration, astrocyte aberrancies and microglia activation in the mSOD1 mice at the early onset of the disease (10-12 weeks). Two ALS models were used: the NSC-34 MN-like cell line expressing mSOD1 (transgenic, TG) or not (wild-type, WT); and the SC organotypic cultures (OCs) from WT and TG mice. Pathological differences between TG and WT SCOCs were investigated. Relatively to the MN models, we used the modulation with pre-miR-124 (only in WT) and that of anti-miR-124 (only in the TG). The isolated secretomes were incubated in WT and TG SCOCs to assess harmful and/or neuroprotective properties. In TG SCOCs we observed: (i) increased necrotic cell death; (ii) disturbed inflammatory-associated miRNAs (increase in miR-21/miR-146a); (iii) and dysregulated neuronal and glial genes (increased CX3CR1, IL-1β, IL-10, SYP, DRP1, GLT-1 and downregulation of iNOS, HMGB1, Dlg4, CX3CL1 and GFAP). WT-MN secretome counteracted pathological markers in TG SCOCs. In contrast, TG MN secretome induced deleterious effects in WT SCOCs. Secretome from miR-124-enriched WT MNs incubated in WT SCOCs led to a profile of miRNAs and protein-coding genes similar to that caused by the TG MN secretome. On the contrary, the secretome from TG MNs depleted in miR-124 restored a deactivated profile in TG SCOCs. Our data reveals MN upregulation of miR-124 as a key player in ALS pathological processes.