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. 2020 Aug 17;21(16):5911. doi: 10.3390/ijms21165911

Figure 1.

Figure 1

Schematic representation of PI3K/Akt/mTOR, ERK1/2-MAPK, and Wnt/β-catenin pathways. (a) PI3K/Akt/mTOR signaling pathway key elements for oligodendrocyte maturation and myelination. Arrowheads imply positive interactions while bars indicate inhibitory signals. BDNF: brain-derived neurotrophic factor, NGF: nerve growth factor, NT3: neurotrophin 3, (s)Nrg1-III: (soluble) Neuregulin 1 type III, BACE1: β-site amyloid precursor protein cleaving enzyme 1, RTKs: receptors tyrosine kinase, IRS-1: insulin receptor substrate 1, PI3K: phosphoinositide-3 kinase, PIP2: phosphatidylinositol (4,5)-biphosphate, PIP3: phosphatidylinositol (3,4,5)-triphosphate, PTEN: phosphatase and tensin homolog, PDK-1: 3-phosphoinositide-dependent protein kinase 1, Akt: protein kinase B, TSC1/2: tuberous sclerosis complex, Rheb: Ras homolog enriched in brain, mTOR: mammalian target of rapamycin, mLST8: target of rapamycin complex subunit LST8, Raptor: regulatory associated protein of mTOR, Rictor: rapamycin-insensitive companion of mTOR, SIN1: Target of rapamycin complex 2 subunit MAPKAP1, p70S6K: Ribosomal protein S6 kinase beta-1, S6RP: Ribosomal protein S6, SREBPs: Sterol regulatory element-binding proteins. (b) ERK1/2-MAPK signaling pathway crucial elements for oligodendrocyte maturation and myelination. Arrowheads imply positive interactions while bars indicate inhibitory signals. PDGF: platelet-derived growth factor, FGF-2: fibroblast growth factor 2, RTKs: receptors tyrosine kinase, IRS-1: insulin receptor substrate 1, Grb2: growth factor receptor-bound protein 2, Sos: son of sevenless, MEK1/2: mitogen-activated protein kinase, ERK1/2: extracellular signal-regulated kinases 1 and 2, p70S6K: Ribosomal protein S6 kinase beta-1, p90RSK: p90 ribosomal S6 kinase, S6RP: Ribosomal protein S6, MyRF: Myelin regulatory factor. (c) Wnt/β-catenin signaling pathway essential elements for oligodendrocyte maturation and myelination. Arrowheads imply positive interactions. Lrp5/6: Lipoprotein receptor-related proteins 5/6, Dvl: disheveled, GSK3: glycogen synthase kinase 3, CK1: casein kinase 1, APC: adenomatous polyposis coli, βcat: β-catenin, TCF4 (TCF2l7): transcription factor 4.