Oligodendrogenesis and Myelin Formation in the Forebrain Require Platelet-derived Growth Factor Receptor-alpha

PDGF receptor signal mediates the contribution of Nestin-positive cell lineage to subcutaneous fat development

The beiging of white adipose tissue (WAT) is expected to improve systemic metabolic conditions; however, the regulation and developmental origin of this process remain insufficiently understood. In the present study, the implication of platelet-derived growth factor receptor alpha (PDGFRα) was examined in the beiging of inguinal WAT (ingWAT) of neonatal mice. Using in vivo Nestin expressing cell (Nestin⁺) lineage tracing and deletion mouse models, we found that, in the mice with Pdgfra gene inactivation in Nestin⁺ lineage (N-PRα-KO mice), the growth of inguinal WAT (ingWAT) was suppressed during neonatal periods as compared with control wild-type mice. In the ingWAT of N-PRα-KO mice, the beige adipocytes appeared earlier that were accompanied by the increased expressions of both adipogenic and beiging markers compared to control wild-type mice. In the perivascular adipocyte progenitor cell (APC) niche of ingWAT, many PDGFRα⁺ cells of Nestin⁺ lineage were recruited in Pdgfra-preserving control mice, but were largely decreased in N-PRα-KO mice. This PDGFRα⁺ cell depletion was replenished by PDGFRα⁺ cells of non-Nestin⁺ lineage, unexpectedly resulting in an increase of total PDGFRα⁺ cell number in APC niche of N-PRα-KO mice over that of control mice. These represented a potent homeostatic control of PDGFRα⁺ cells between Nestin⁺ and non-Nestin⁺ lineages that was accompanied by the active adipogenesis and beiging as well as small WAT depot. This highly plastic nature of PDGFRα⁺ cells in APC niche may contribute to the WAT remodeling for the therapeutic purpose against metabolic diseases.

Identifying Genes that Affect Differentiation of Human Neural Stem Cells and Myelination of Mature Oligodendrocytes

Human neural stem cells (NSCs) are self-renewing, multipotent cells of the central nervous system (CNS). They are characterized by their ability to differentiate into a range of cells, including oligodendrocytes (OLs), neurons, and astrocytes, depending on exogenous stimuli. An efficient and easy directional differentiation method was developed for obtaining large quantities of high-quality of human OL progenitor cells (OPCs) and OLs from NSCs. RNA sequencing, immunofluorescence staining, flow cytometry, western blot, label-free proteomic sequencing, and qPCR were performed in OL lines differentiated from NSC lines. The changes in the positive rate of typical proteins were analyzed expressed by NSCs, neurons, astrocytes, OPCs, and OLs. We assessed Gene Ontology (GO) enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways of differentially expressed (DE) messenger RNAs (mRNAs) related to the differentiation of NSCs and the maturation of OLs. The percentage of NSCs differentiated into neurons, astrocytes, and OLs was 82.13%, 80.19%, and 90.15%, respectively. We found that nestin, PAX6, Musashi, and vimentin were highly expressed in NSCs; PDGFR-α, A2B5, NG2, OLIG2, SOX10, and NKX2-2 were highly expressed in OPCs; and CNP, GALC, PLP1, and MBP were highly expressed in OLs. RNA sequencing, western blot and qPCR revealed that ERBB4 and SORL1 gradually increased during NSC–OL differentiation. In conclusion, NSCs can differentiate into neurons, astrocytes, and OLs efficiently. PDGFR-α, APC, ID4, PLLP, and other markers were related to NSC differentiation and OL maturation. Moreover, we refined a screening method for ERBB4 and SORL1, which may underlie NSC differentiation and OL maturation.

Graphical Abstract

Potential unreported genes and proteins may regulate differentiation of human neural stem cells into oligodendrocyte lineage. Neural stem cells (NSCs) can differentiate into neurons, astrocytes, and oligodendrocyte (OLs) efficiently. By analyzing the DE mRNAs and proteins of NSCs and OLs lineage, we could identify reported markers and unreported markers of ERBB4 and SORL1 that may underlie regulate NSC differentiation and OL maturation.

miR-124 regulates early isolation-induced social abnormalities via inhibiting myelinogenesis in the medial prefrontal cortex

Patients with autism spectrum disorder (ASD) typically experience substantial social isolation, which may cause secondary adverse effects on their brain development. miR-124 is the most abundant miRNA in the human brain, acting as a pivotal molecule regulating neuronal fate determination. Alterations of miR-124 maturation or expression are observed in various neurodevelopmental, neuropsychiatric, and neurodegenerative disorders. In the present study, we analyzed a panel of brain-enriched microRNAs in serums from 2 to 6 year old boys diagnosed with ASD. The hsa-miR-124 level was found significantly elevated in ASD boys than in age and sex-matched healthy controls. In an isolation-reared weanling mouse model, we evidenced elevated mmu-miR-124 level in the serum and the medial prefrontal cortex (mPFC). These mice displayed significant sociability deficits, as well as myelin abnormality in the mPFC, which was partially rescued by expressing the miR-124 sponge in the bilateral mPFC, ubiquitously or specifically in oligodendroglia. In cultured mouse oligodendrocyte precursor cells, introducing a synthetic mmu-miR-124 inhibited the differentiation process through suppressing expression of nuclear receptor subfamily 4 group A member 1 (Nr4a1). Overexpressing Nr4a1 in the bilateral mPFC also corrected the social behavioral deficits and myelin impairments in the isolation-reared mice. This study revealed an unanticipated role of the miR-124/Nr4a1 signaling in regulating early social experience-dependent mPFC myelination, which may serve as a potential therapy target for social neglect or social isolation-related neuropsychiatric disorders.

Integrated bioinformatics analysis identifies the effects of Sema3A/NRP1 signaling in oligodendrocytes after spinal cord injury in rats

Objective

To investigate the effect of Sema3A/NRP1 signaling in oligodendrocytes (OLs) after spinal cord injury.

Methods

Three analysis strategies, namely differential expression gene analysis, Gene Ontology (GO) enrichment, and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis, were applied. The protein-protein interaction (PPI) network was constructed using the STRING website to explore the correlation between Sema3A/NRP1 and oligodendrocytes. Then, the T10 spinal cord segment of rats was injured by the Allen method to establish a spinal cord injury (SCI) model. Real-time quantitative PCR, Western blotting, Nissl staining and immunofluorescence staining were used to detect the effect of Sema3A/NRP1 signaling on oligodendrocytes in vivo.

Results

After the SCI model was established, significantly fewer oligodendrocytes were observed. At the same time, R software was used to analyze the expression of related genes, and NRP1 expression was increased. PCR also demonstrated similar results, and NRP1 ligand Sema3A was also upregulated. KEGG and GO functional enrichment analysis indicated that the SCI model was mainly related to cytokine interaction, cell proliferation, differentiation and maturation. Interestingly, we found that NRP1 was involved in semaphorin-plexin signaling pathway neuronal projection guidance and axon guidance, mediating cell growth and migration. Moreover, Sema3A/NRP1 signaling was closely associated with platelet-derived growth factor receptor α (PDGFRα) in the PPI network. When Sema3A/NRP1 signaling was specifically blocked at early stages, PDGFRα expression was effectively inhibited, and the expression of OLs was promoted. Furthermore, inhibition of Sema3A/NRP1 signaling increased the Basso-Beattie-Bresnahan (BBB) score of lower limb motor function in SCI rats and promoted the survival of motor neurons in the ventral horn of the injured spinal cord.

Conclusion

Our data suggest that Sema3A/NRP1 signaling may regulate the development of OPCs and OLs after SCI, thereby affecting functional recovery.

Life-long oligodendrocyte development and plasticity

Oligodendrocyte precursor cells (OPCs) originate in localized germinal zones in the embryonic neural tube, then migrate and proliferate to populate the entire central nervous system, both white and gray matter. They divide and generate myelinating oligodendrocytes (OLs) throughout postnatal and adult life. OPCs express NG2 and platelet-derived growth factor receptor alpha subunit (PDGFRα), two functionally important cell surface proteins, which are also widely used as markers for OPCs. The proliferation of OPCs, their terminal differentiation into OLs, survival of new OLs, and myelin synthesis are orchestrated by signals in the local microenvironment. We discuss advances in our mechanistic understanding of paracrine effects, including those mediated through PDGFRα and neuronal activity-dependent signals such as those mediated through AMPA receptors in OL survival and myelination. Finally, we review recent studies supporting the role of new OL production and “adaptive myelination” in specific behaviours and cognitive processes contributing to learning and long-term memory formation. Our article is not intended to be comprehensive but reflects the authors’ past and present interests.

Sphingosine-1-Phosphate Receptor Modulators and Oligodendroglial Cells: Beyond Immunomodulation

Multiple sclerosis (MS) is an autoimmune inflammatory disease characterized by demyelination, axonal loss, and synaptic impairment in the central nervous system (CNS). The available therapies aim to reduce the severity of the pathology during the early inflammatory stages, but they are not effective in the chronic stage of the disease. In this phase, failure in endogenous remyelination is associated with the impairment of oligodendrocytes progenitor cells (OPCs) to migrate and differentiate into mature myelinating oligodendrocytes. Therefore, stimulating differentiation of OPCs into myelinating oligodendrocytes has become one of the main goals of new therapeutic approaches for MS. Different disease-modifying therapies targeting sphingosine-1-phosphate receptors (S1PRs) have been approved or are being developed to treat MS. Besides their immunomodulatory effects, growing evidence suggests that targeting S1PRs modulates mechanisms beyond immunomodulation, such as remyelination. In this context, this review focuses on the current understanding of S1PR modulators and their direct effect on OPCs and oligodendrocytes.