Crosstalk between NGF and micro-RNA219-5p in controlling oligodendrocytes differentiation

Introduction: The intricate signaling between neurotrophins and cytokines governs myelin repair and supports the role of NGF as a key regulator of oligodendrocytes (OL) wellbeing and myelinization. This regulatory homeostatic process could play a significant role in white matter disorders, such as Multiple Sclerosis (MS). The current view is that NGF promotes myelination in the peripheral nervous system, while inhibiting it in the CNS. In agreement with an inhibitory role of NGF on myelination by OLs, we have demonstrated that miR-219-5p, a key positive regulator of oligodendrogenesis, is up-regulated in a mouse model of postnatal NGF neutralization (AD11 Tg mice). We characterized the interplay between NGF and miR-219-5p in OLs derived from adult neural stem cells (aNSCs), in order to understand the cellular and molecular mechanisms underlying OL differentiation and MBP production. This might provide information for the development of novel therapeutic targets for remyelination. Aims: The specific aims are the following: 1) Understanding how NGF signaling regulates miR-219-5p to promote oligodendrogenesis in WT and AD11-derived OL precursor cells (OPCs); 2) characterizing the role of proNGF/NGF imbalance on miR-219-5p modulation; 3) modulating miR-219-5p expression in order to promote OLs differentiation and myelination. Methods: OPC cultures have been established from adult neural stem cells (aNSCs) derived from WT and AD11 Tg mice dentate gyrus in order to: i) characterize the expression of NGF receptors (p75, TrkA, Sort) during the different stages of oligodendrogenesis, by Immunofluorescence and qReal-Time PCR experiments; ii) modulate miR-219-5p expression by Lentiviral delivery of miR-219-5p or of anti-miR-219-5p; iii) modulate miR-219-5p expression by NGF or anti-NGF administration. Results: Our data shows that AD11 aNSCs express higher levels of miR-219-5p compared to WT and give rise to more O4-positive OL, when differentiated in culture. In addition to that, NGF treatment of AD11 aNSCs down-regulates miR-219-5p expression and inhibits OL differentiation; conversely, anti-NGF administration to WT aNSCs down-regulates miR-219-5p and reproduces the AD11 OLs phenotype. Conclusions: Our data demonstrates that NGF controls oligodendrogenesis by modulating miR219-5p levels. We are currently characterizing the molecular pathways underlying this modulation, in an attempt to identify new therapeutic targets for remyelination.