Involvement of the miR-363-5p/P2RX4 Axis in Regulating Schwann Cell Phenotype after Nerve Injury

Eun-Jung Sohn,Hwan-Tae Park,Yun-Kyeong Nam

doi:10.3390/ijms222111601

Eun-Jung Sohn, Hwan-Tae Park + Show 1 more

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https://doi.org/10.3390/ijms222111601

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Abstract

Although microRNAs (miRNAs or miRs) have been studied in the peripheral nervous system, their function in Schwann cells remains elusive. In this study, we performed a microRNA array analysis of cyclic adenosine monophosphate (cAMP)-induced differentiated primary Schwann cells. KEGG pathway enrichment analysis of the target genes showed that upregulated miRNAs (mR212-5p, miR335, miR20b-5p, miR146b-3p, and miR363-5p) were related to the calcium signaling pathway, regulation of actin cytoskeleton, retrograde endocannabinoid signaling, and central carbon metabolism in cancer. Several key factors, such as purinergic receptors (P2X), guanine nucleotide-binding protein G(olf) subunit alpha (GNAL), P2RX5, P2RX3, platelet-derived growth factor receptor alpha (PDGFRA), and inositol 1,4,5-trisphosphate receptor type 2 (ITPR2; calcium signaling pathway) are potential targets of miRNAs regulating cAMP. Our analysis revealed that miRNAs were differentially expressed in cAMP-treated Schwann cells; miRNA363-5p was upregulated and directly targeted the P2X purinoceptor 4 (P2RX4)-UTR, reducing the luciferase activity of P2RX4. The expression of miRNA363-5p was inhibited and the expression of P2RX4 was upregulated in sciatic nerve injury. In contrast, miRNA363-5p expression was upregulated and P2RX4 expression was downregulated during postnatal development. Of note, a P2RX4 antagonist counteracted myelin degradation after nerve injury and increased pERK and c-Jun expression. Interestingly, a P2RX4 antagonist increased the levels of miRNA363-5p. This study suggests that a double-negative feedback loop between miRNA363-5p and P2RX4 contributes to the dedifferentiation and migration of Schwann cells after nerve injury.

Highlights

Schwann cells, major glial cells of the peripheral nervous system (PNS), undergo biochemical and morphological alterations after nerve injury, following which the distal stump of the peripheral nerve sheds myelin-derived fragments and undergoes axonal degeneration, known as Wallerian degeneration
The miRNA array analysis revealed that 47 miRNAs, including miRNA20b-5p, miRNA146b-3p, miRNA 363-5p, and miRNA335, were significantly upregulated (>2-fold) in cyclic adenosine monophosphate (cAMP)-treated Schwann cells compared with the untreated control (Figure 1A, Supplementary Table S1)
Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment and gene ontology (GO) term analyses of the targets showed that the upregulated miRNAs were related to the calcium signaling pathway, regulation of the actin cytoskeleton, cell migration, response to ATP, and endocytosis, suggesting that they contribute to the phenotypic modulation of Schwann cells

Summary

Introduction

Major glial cells of the peripheral nervous system (PNS), undergo biochemical and morphological alterations after nerve injury, following which the distal stump of the peripheral nerve sheds myelin-derived fragments and undergoes axonal degeneration, known as Wallerian degeneration. During this stage, macrophages migrate to the injured site, and Schwann cells terminate transcription factor activity in the myelination program to express myelin protein zero (MPZ), myelin basic protein (MBP), and. Purinergic receptors (P2X) are ligand-gated ion channels that respond to ATP binding, enabling ions (K+ , Na+ , and Ca2+ ) to cross the cell membrane [2].

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