Myelin-forming oligodendrocytes in the central nervous system (CNS) and Schwann cells in the peripheral nervous system (PNS) are essential for structural and functional homeostasis of nervous tissue. Albeit with certain similarities, the regulation of CNS and PNS myelination is executed differently. Recent advances highlight the coordinated regulation of oligodendrocyte myelination by amino-acid sensing and growth factor signaling pathways. In this review, we discuss novel insights into the understanding of differential regulation of oligodendrocyte and Schwann cell biology in CNS and PNS myelination, with particular focus on the roles of growth factor-stimulated RHEB-mTORC1 and GATOR2-mediated amino-acid sensing/signaling pathways. We also discuss recent progress on the metabolic regulation of oligodendrocytes and Schwann cells and the impact of their dysfunction on neuronal function and disease.
Amino Acids ; Myelin Sheath/metabolism* ; Schwann Cells/metabolism* ; Oligodendroglia/metabolism* ; Signal Transduction ; Intercellular Signaling Peptides and Proteins/metabolism*

Nerve regeneration after injury requires proper axon alignment to bridge the lesion site and myelination to achieve functional recovery. Transplanted scaffolds with aligned channels, have been shown to induce axon growth to some extent. However, the penetration of axons into the microchannels remain a challenge, influencing the functional recovery of regenerated nerves. We previously demonstrated that the size of microchannels exerts significant impact on Schwann cells (SCs) migration. Here we demonstrate that migration of SCs promotes, significantly, the dorsal root ganglion (DRG) neurons to extend axons into three-dimensional channels and form aligned fascicular-like axon tracts. Moreover, the migrating SCs attach and wrap around the aligned axons of DRG neurons in the microchannels and initiate myelination. The SCs release growth factors that provide chemotactic signals to the regenerating axons, similar to the response achieved with nerve growth factor (NGF), but with the additional capability of promoting myelination, thereby demonstrating the beneficial effects of including SCs over NGF alone in enhancing axon penetration and myelination in three-dimensional microchannels.
Axons* ; Diagnosis-Related Groups ; Ganglia, Spinal ; Intercellular Signaling Peptides and Proteins ; Myelin Sheath ; Nerve Growth Factor ; Nerve Regeneration ; Neurons ; Schwann Cells*

Oligodendrocytes (OLs) are myelinating glial cells that form myelin sheaths around axons to ensure rapid and focal conduction of action potentials. Here, we found that an axonal outgrowth regulatory molecule, AATYK (apoptosis-associated tyrosine kinase), was up-regulated with OL differentiation and remyelination. We therefore studied its role in OL differentiation. The results showed that AATYK knockdown inhibited OL differentiation and the expression of myelin genes in vitro. Moreover, AATYK-deficiency maintained the proliferation status of OLs but did not affect their survival. Thus, AATYK is essential for the differentiation of OLs.
Animals ; Animals, Newborn ; Apoptosis Regulatory Proteins ; genetics ; metabolism ; Cell Differentiation ; drug effects ; physiology ; Cell Proliferation ; drug effects ; genetics ; Cells, Cultured ; Cuprizone ; toxicity ; Demyelinating Diseases ; chemically induced ; metabolism ; pathology ; Embryo, Mammalian ; Gene Expression Regulation, Developmental ; genetics ; Ki-67 Antigen ; metabolism ; Mice ; Mice, Inbred C57BL ; Myelin Basic Protein ; metabolism ; Myelin Proteolipid Protein ; metabolism ; Myelin Sheath ; drug effects ; metabolism ; Oligodendroglia ; drug effects ; metabolism ; Protein-Tyrosine Kinases ; genetics ; metabolism ; RNA, Small Interfering ; genetics ; metabolism ; Rats ; Rats, Sprague-Dawley

A previous study has indicated that Krüppel-like factor 7 (KLF7), a transcription factor that stimulates Schwann cell (SC) proliferation and axonal regeneration after peripheral nerve injury, is a promising therapeutic transcription factor in nerve injury. We aimed to identify whether inhibition of microRNA-146b (miR-146b) affected SC proliferation, migration, and myelinated axon regeneration following sciatic nerve injury by regulating its direct target KLF7. SCs were transfected with miRNA lentivirus, miRNA inhibitor lentivirus, or KLF7 siRNA lentivirus in vitro. The expression of miR146b and KLF7, as well as SC proliferation and migration, were subsequently evaluated. In vivo, an acellular nerve allograft (ANA) followed by injection of GFP control vector or a lentiviral vector encoding an miR-146b inhibitor was used to assess the repair potential in a model of sciatic nerve gap. miR-146b directly targeted KLF7 by binding to the 3'-UTR, suppressing KLF7. Up-regulation of miR-146b and KLF7 knockdown significantly reduced the proliferation and migration of SCs, whereas silencing miR-146b resulted in increased proliferation and migration. KLF7 protein was localized in SCs in which miR-146b was expressed in vivo. Similarly, 4 weeks after the ANA, anti-miR-146b increased KLF7 and its target gene nerve growth factor cascade, promoting axonal outgrowth. Closer analysis revealed improved nerve conduction and sciatic function index score, and enhanced expression of neurofilaments, P0 (anti-peripheral myelin), and myelinated axon regeneration. Our findings provide new insight into the regulation of KLF7 by miR-146b during peripheral nerve regeneration and suggest a potential therapeutic strategy for peripheral nerve injury.
Animals ; Cell Movement ; genetics ; Cell Proliferation ; genetics ; Disease Models, Animal ; Female ; Ganglia, Spinal ; cytology ; Gene Expression Regulation ; genetics ; physiology ; HEK293 Cells ; Humans ; Kruppel-Like Transcription Factors ; genetics ; metabolism ; Male ; MicroRNAs ; genetics ; metabolism ; Motor Endplate ; genetics ; Myelin P0 Protein ; metabolism ; Nerve Regeneration ; genetics ; physiology ; Nerve Tissue Proteins ; metabolism ; RNA, Small Interfering ; genetics ; metabolism ; Rats ; Rats, Sprague-Dawley ; Rats, Wistar ; Sciatic Neuropathy ; metabolism ; surgery ; therapy

Myelin is a specialized structure of the nervous system that both enhances electrical conductance and insulates neurons from external risk factors. In the central nervous system, polarized oligodendrocytes form myelin by wrapping processes in a spiral pattern around neuronal axons through myelin-related gene regulation. Since these events occur at a distance from the cell body, post-transcriptional control of gene expression has strategic advantage to fine-tune the overall regulation of protein contents in situ. Therefore, many research interests have been focused to identify RNA binding proteins and their regulatory mechanism in myelinating compartments. Fragile X mental retardation protein (FMRP) is one such RNA binding protein, regulating its target expression by translational control. Although the majority of works on FMRP have been performed in neurons, it is also found in the developing or mature glial cells including oligodendrocytes, where its function is not well understood. Here, we will review evidences suggesting abnormal translational regulation of myelin proteins with accompanying white matter problem and neurological deficits in fragile X syndrome, which can have wider mechanistic and pathological implication in many other neurological and psychiatric disorders.
Axons ; Cell Body ; Central Nervous System ; Fragile X Mental Retardation Protein* ; Fragile X Syndrome ; Gene Expression ; Myelin Proteins* ; Myelin Sheath* ; Nervous System ; Neuroglia ; Neurons ; Oligodendroglia ; Risk Factors ; RNA-Binding Proteins ; White Matter

OBJECTIVETo analyze mutation of the PMP22 gene in a pedigree affected with Charcot-Marie-Tooth disease.

METHODSGenomic DNA was extracted from peripheral blood samples of the proband and members from his family, and fetal DNA was extracted from amniotic fluid sample. Multiplex ligation-dependent probe amplification (MLPA) and array-based comparative genomic hybridization (array-CGH) analyses were carried out to determine the copy number of the PMP22 gene. Sanger sequencing was carried out to detect point mutations of the PMP22 gene.

RESULTSA heterozygous duplication of the PMP22 gene was detected in the proband and his father, while no point mutation, insertion or deletion was found in them. No duplication or deletion of the PMP22 gene was found in other family members.

CONCLUSIONBased on clinical symptoms and genetic findings, the heterozygous duplication of the PMP22 gene is probably the cause of the disease in the proband. The fact that the father has carried the same duplication but with no detectable symptom may be due to irregular transmission pattern of the mutation. Genetic counseling for the family should therefore be with caution.

Adult ; Charcot-Marie-Tooth Disease ; genetics ; Comparative Genomic Hybridization ; methods ; DNA Mutational Analysis ; Family Health ; Female ; Gene Dosage ; Gene Duplication ; Genetic Predisposition to Disease ; genetics ; Heterozygote ; Humans ; Male ; Multiplex Polymerase Chain Reaction ; methods ; Myelin Proteins ; genetics ; Pedigree

OBJECTIVETo study the effects of Bushen Yisui Capsule (, BSYSC) on the oligodendrocyte lineage genes (Olig) 1 and Olig2 in C57BL/6 mice with experimental autoimmune encephalomyelitis (EAE) in order to explore the remyelination effect of BSYSC.

METHODSThe mice were randomly divided into normal control (NC), EAE model (EAE-M), prednisone acetate (PA, 6 mg/kg), BSYSC high-dose (3.02 g/kg) and BSYSC low-dose (1.51 g/kg) groups. The mice were induced by immunization with myelin oligodendrocyte glycoprotein (MOG) 35-55. The neurological function scores were assessed once daily. The pathological changes in mice brains were observed with hematoxylin-eosin (HE) staining and transmission electron microscope (TEM). The protein expressions of myelin basic protein (MBP), Olig1 and Olig2 in brains were measured by immunohistochemistry. The mRNA expressions of Olig1 and Olig 2 was also determined by quantitative real-time polymerase chain reaction.

RESULTSCompared with the EAE-M mice, (1) the neurological function scores were significantly decreased in BSYSC-treated mice on days 22 to 40 (P<0.01); (2) the inflammatory cells and demyelination in brains were reduced in BSYSC-treated EAE mice; (3) the protein expression of MBP was markedly increased in BSYSC-treated groups on day 18 and 40 respectively (P<0.05 or P<0.01); (4) the protein expression of Olig1 was increased in BSYSC (3.02 g/kg)-treated EAE mice on day 40 (P<0.01). Protein and mRNA expression of Olig2 was increased in BSYSC-treated EAE mice on day 18 and 40 (P<0.01).

CONCLUSIONThe effects of BSYSC on reducing demyelination and promoting remyelination might be associated with the increase of Olig1 and Olig2.

Animals ; Basic Helix-Loop-Helix Transcription Factors ; genetics ; metabolism ; Brain ; drug effects ; pathology ; ultrastructure ; Bromodeoxyuridine ; metabolism ; Capsules ; Drugs, Chinese Herbal ; pharmacology ; therapeutic use ; Encephalomyelitis, Autoimmune, Experimental ; drug therapy ; genetics ; pathology ; physiopathology ; Female ; Fluorescent Antibody Technique ; Mice, Inbred C57BL ; Myelin-Oligodendrocyte Glycoprotein ; metabolism ; Nerve Tissue Proteins ; genetics ; metabolism ; Oligodendrocyte Transcription Factor 2 ; RNA, Messenger ; genetics ; metabolism

OBJECTIVE: DNA methylation has been shown to be a potential biomarker for early cancer detection. The aim of this study was to evaluate DNA methylation profiles according to liquid-based Pap (LBP) test results and to assess their diagnostic value in a Korean population. METHODS: A total of 205 patients with various Papanicolaou test results were enrolled to this study (negative, 26; atypical squamous cells of undetermined significance, 39; low grade squamous intraepithelial lesion, 44; high grade squamous intraepithelial lesion (HSIL), 48; and cancer, 48). DNA methylation analysis of four genes, ADCYAP1, PAX1, MAL, and CADM1, was performed on residual cervical cells from LBP samples using a quantitative bisulfite pyrosequencing method. To evaluate the diagnostic performance of the four methylated genes for cancer detection, receiver operating characteristic (ROC) curves were drawn. Sensitivities and specificities were also tested at cutoffs determined from the ROC curves. RESULTS: Cervical cancer cells showed dramatically increased methylation levels for the four genes analyzed. ADCYAP1 and PAX1 also trended toward elevated methylation levels in HSIL samples, although the levels were much lower than those in cancer cells. The sensitivities of methylated ADCYAP1, PAX1, MAL, and CADM1 for the detection of cancer were 79.2%, 75.0%, 70.8%, and 52.1%, and the specificities were 92.0%, 94.0%, 94.7%, and 94.0%, respectively. Methylated ADCYAP1 and PAX1 demonstrated relatively better discriminatory ability than did methylated MAL and CADM1 (area under the curves 0.911 and 0.916 vs. 0.854 and 0.756, respectively). CONCLUSION: DNA methylation status, especially in the ADCYAP1 and PAX1 genes, showed relatively good specificity, ranging from 90% to 94%. The possible additive and complementary roles of DNA methylation testing with respect to conventional cervical cancer screening programs will need to be validated in prospective population-based studies.
Alphapapillomavirus/genetics ; *Atypical Squamous Cells of the Cervix/pathology/virology ; Cell Adhesion Molecules/genetics ; *DNA Methylation ; Female ; Genotype ; Humans ; Immunoglobulins/genetics ; Myelin and Lymphocyte-Associated Proteolipid Proteins/genetics ; Paired Box Transcription Factors/genetics ; Papanicolaou Test ; Pituitary Adenylate Cyclase-Activating Polypeptide/genetics ; ROC Curve ; Squamous Intraepithelial Lesions of the Cervix/*genetics/pathology/virology ; Uterine Cervical Neoplasms/*genetics/pathology/virology ; Vaginal Smears

PURPOSE: Charcot-Marie-Tooth disease (CMT) is a peripheral neuropathy mainly divided into CMT type 1 (CMT1) and CMT2 according to the phenotype and genotype. Although molecular pathologies for each genetic causative have not been revealed in CMT2, the correlation between cell death and accumulation of misfolded proteins in the endoplasmic reticulum (ER) of Schwann cells is well documented in CMT1. Establishment of in vitro models of ER stress-mediated Schwann cell death might be useful in developing drug-screening systems for the treatment of CMT1. MATERIALS AND METHODS: To develop high-throughput screening (HTS) systems for CMT1, we generated cell models using transient expression of mutant proteins and chemical induction. RESULTS: Overexpression of wild type and mutant peripheral myelin protein 22 (PMP22) induced ER stress. Similar results were obtained from mutant myelin protein zero (MPZ) proteins. Protein localization revealed that expressed mutant PMP22 and MPZ proteins accumulated in the ER of Schwann cells. Overexpression of wild type and L16P mutant PMP22 also reduced cell viability, implying protein accumulation-mediated ER stress causes cell death. To develop more stable screening systems, we mimicked the ER stress-mediated cell death in Schwann cells using ER stress inducing chemicals. Thapsigargin treatment caused cell death via ER stress in a dose dependent manner, which was measured by expression of ER stress markers. CONCLUSION: We have developed genetically and chemically induced ER stress models using Schwann cells. Application of these models to HTS systems might facilitate the elucidation of molecular pathology and development of therapeutic options for CMT1.
Cell Death ; Cell Survival ; Charcot-Marie-Tooth Disease* ; Endoplasmic Reticulum ; Endoplasmic Reticulum Stress ; Genotype ; Mass Screening* ; Mutant Proteins ; Myelin P0 Protein ; Myelin Sheath ; Pathology, Molecular ; Peripheral Nervous System Diseases ; Phenotype ; Schwann Cells ; Thapsigargin

OBJECTIVETo study the effects of Jisuikang (Chinese characters) on Nogo-NgR gene expression, and to explore the protective effects and mechanism of Jisuikang (Chinese characters) on spinal cord injury in rats.

METHODSOne hundred eighty female rats were randomly assigned to 6 groups(30 rats per group). Sham group: T10 lamina was resected only and spinal cord was untreated. Model group: spine cord injury (SCI) was created with a modified impinger of Allen's by impacting on the T10 spinal cord. Prednisolone group: Prednisolone (0.06 g/kg) was given by intragastric administration at a time interval of 24 hours after operation. The Jisuikang (Chinese characters) high, moderate and low dose groups: Jisuikang (Chinese characters) was supplied with different dose (50 g/kg, 25 g/kg, 12.5 g/kg) by intragastric administration in rats after operation,for the first time at 30 min after surgery. Animals were killed 3, 7, 14 days after surgery. The expression levels of Nogo-A and NgR were observed by Western Blot and Real-time PCR.

RESULTSThe expression of Nogo-A and NgR was at the basic level at all time points in sham group. Compared with model group, the protein expression levels of Nogo-A and NgR in sham, prednisolone, Jisuikang (Chinese characters) moderate dose groups were statistically significant at all time points (P < 0.05). No difference was found in Jisuikang (Chinese characters) high and low dose groups (P > 0.05). Three days after surgery, the mRNA levels of Nogo-A and NgR in treatment group were significantly lower than that in model group (P < 0.01); 7 days after surgery,Nogo-A and NgR mRNA expression were dramatically upregulated and peaked; 14 days after operation, the expression was decreased, but still significantly higher than that in other treatment groups (P < 0.01). Prednisolone and Jisuikang (Chinese characters) moderate dose groups showed the most significant effects among all groups,but there was no statistically significant difference between two groups (P > 0.05).

CONCLUSIONThe decoction Jisuikang (Chinese characters) can promote the nerve cell regeneration by regulating Nogo-A and NgR gene expression, activating Nogo- NgR signaling pathways after acute spinal cord injury.

Animals ; Female ; GPI-Linked Proteins ; analysis ; genetics ; physiology ; Medicine, Chinese Traditional ; Myelin Proteins ; analysis ; genetics ; physiology ; Nerve Regeneration ; drug effects ; Nogo Proteins ; Nogo Receptor 1 ; Rats ; Rats, Sprague-Dawley ; Receptors, Cell Surface ; analysis ; genetics ; physiology ; Signal Transduction ; drug effects ; Spinal Cord Injuries ; drug therapy ; metabolism