microRNAs dysregulated in multiple sclerosis affect the differentiation of CG-4 cells, an oligodendrocyte progenitor cell line

Remyelination in multiple sclerosis (MS) is from the start of the disease imperfect, and strongly decreases with its progression, mainly due to the harm on oligodendrocyte progenitor cells (OPCs), causing neurodegeneration and resulting in irreversible neurological deficits. Therapeutic strategies promoting remyelination are still very preliminary and lack within the current treatment panel of MS. In a previous study we have identified 21 microRNAs dysregulated mostly in the CSF of relapsing and/or remitting MS patients. Here, we observed that among these, the majority of 13 transfected microRNA mimics decreased the differentiation of an OPC cell line called CG-4. Herein we support by RNA sequencing and independent RT-qPCR analyses that miR-33-3p, miR-34c-5p, miR-124-5p, and miR-145-5p impede OPC differentiation as evidenced by the downregulation of premyelinating oligodendrocyte (OL) (Tcf7l2, Cnp [except for miR-145-5p]) and mature OL (Plp1, Mbp, Mobp) markers, whereas only miR-214-3p promotes OPC differentiation. We further propose a comprehensive exploration of their change in cell fate through Gene Ontology enrichment analysis. We finally confirm by RT-qPCR analysis the downregulation of several predicted mRNA targets for each microRNA that possibly support their effect on OPC differentiation by very distinctive mechanisms, of which some are still unexplored in OPC/OL physiology. We hereby open new perspectives in the research on OPC differentiation and the pathophysiology of demyelination/remyelination, and possibly even in the research on new remyelinating therapeutic strategies in the scope of MS. Overall design: We aimed to investigate the effect of several microRNAs on the differentiation of oligodendrocyte progenitor cells (OPCs). Therefore CG-4 cells (an OPC cell line) were transfected with each microRNA mimic separately and were then cultured in differentiation medium for 48h We performed RNA-sequencing on the transfected cells (5 different microRNAs) and controls (proliferation vehicle control, differentiation vehicle control, differentiation microRNA negative control) We compared each microRNA condition to each control regarding differentially expressed genes and Gene Ontology enrichment analysis