Abstract
Multiple sclerosis (MS) is an autoimmune disease characterized by demyelination and neurodegeneration in the brain, spinal cord and optic nerve. Neuronal degeneration and death underlie progressive forms of MS and cognitive dysfunction. Neuronal damage is triggered by numerous harmful factors in the brain that engage diverse signalling cascades in neurons thus therapeutic approaches to protect neurons will need to focus on agents that can target broad biological processes. To target the broad spectrum of signaling events that mediate neurodegeneration in MS we have focused on non-coding small microRNAs (miRNAs). microRNAs are epigenetic regulators of protein expression, targeting messenger RNAs (mRNAs) and inhibiting their translation. Dysregulation of miRNAs has been described in many neurodegenerative diseases including MS. In this study we identified two miRNAs, miR-223-3p and miR-27a-3p, that were upregulated in neurons in the experimental autoimmune encephalomyelitis (EAE) mouse model of CNS inflammation and in active MS lesions. Overexpression of miR-27a-3p or miR-223-3p protected dissociated cortical neurons from degeneration in response to peripheral blood mononuclear cell conditioned media (PBMC-CM). Introduction of miR-223-3p in vivo in mouse retinal ganglion cells (RGCs) protected RGC axons from degeneration in the EAE model. By in silico analysis we found that mRNAs in the glutamate receptor (GluR) pathway are enriched in miR-27a-3p and miR-223-3p targets. Antagonism of the GluR pathway protected neurons from PBMC-CM-dependent degeneration. Our results suggest that miR-223-3p and miR-27a-3p are upregulated in response to inflammation to mediate a compensatory neuroprotective gene expression program that desensitizes neurons to glutamate by downregulating mRNAs involved in GluR signalling.
- Abbreviations
- 3’ untranslated region
- (3’UTR)
- AMPA receptor
- (AMPAR)
- benzyl ether
- (DBE)
- Canadian Council on Animal Care
- (CCAC)
- CellTitre-Glo
- (CTG)
- central nervous system
- (CNS)
- days in vitro
- (DIV)
- days post injection
- (dpi)
- embryonic day
- (E)
- experimental autoimmune encephalomyelitis
- (EAE)
- fetal bovine serum
- (FBS)
- glutamate receptor
- (GluR)
- gonadotropin-releasing hormone
- (GnRH)
- immunolabeling-enabled three dimensional imaging of solvent cleared organs
- (iDISCO)
- knockout
- (KO)
- laser capture microdissection
- (LCM)
- messenger RNA
- (mRNA)
- methanl
- (MeOH)
- microRNA
- (miRNA)
- multiple sclerosis
- (MS)
- Multiwavelength Cell Scoring
- (MWSC)
- NMDA receptor
- (NMDAR)
- optimal cutting temperature
- (OCT)
- optic nerve
- (ON)
- paraformaldehyde
- (PFA)
- peripheral blood mononuclear cell
- (PBMC)
- PBMC conditioned media
- (PBMC-CM)
- poly-l-lysine
- (PLL)
- primary progressive multiple sclerosis,
- (PPMS) polymerase chain reaction (PCR)
- primary progressive multiple sclerosis
- (PPMS)
- Protein ANalysis THrough Evolutionary Relationships
- (PANTHER)
- quantitative RT-PCR
- (RTqPCR)
- relapsing-remitting multiple sclerosis
- (RRMS)
- retinal ganglion cell
- (RGC)
- tetrahydrofuran
- (THF)
- wild type
- (WT)
Footnotes
↵* co-contributing author