Modulating endogenous regenerative processes may represent a suitable treatment for central nervous system (CNS) injuries, such as stroke or trauma. Neural stem/progenitor cells (NS/PCs), which naturally reside in the subventricular zone (SVZ) of the adult brain, proliferate and differentiate to other cell types, and therefore may compensate the negative consequences of ischemic injury. The fate of NS/PCs in the developing brain is largely influenced by Wingless/Integrated (Wnt) signaling; however, its role in the differentiation of adult NS/PCs under ischemic conditions is still enigmatic. In our previous study, we identified the Wnt/β-catenin signaling pathway as a factor promoting neurogenesis at the expense of gliogenesis in neonatal mice. In this study, we used adult transgenic mice in order to assess the impact of the canonical Wnt pathway modulation (inhibition or hyper-activation) on NS/PCs derived from the SVZ, and combined it with the middle cerebral artery occlusion (MCAO) to disclose the effect of focal cerebral ischemia (FCI). Based on the electrophysiological properties of cultured cells, we first identified three cell types that represented in vitro differentiated NS/PCs - astrocytes, neuron-like cells, and precursor cells. Following FCI, we detected fewer neuron-like cells after Wnt signaling inhibition. Furthermore, the immunohistochemical analysis revealed an overall higher expression of cell-type-specific proteins after FCI, indicating increased proliferation and differentiation rates of NS/PCs in the SVZ. Remarkably, Wnt signaling hyper-activation increased the abundance of proliferating and neuron-like cells, while Wnt pathway inhibition had the opposite effect. Finally, the expression profiling at the single cell level revealed an increased proportion of neural stem cells and neuroblasts after FCI. These observations indicate that Wnt signaling enhances NS/PCs-based regeneration in the adult mouse brain following FCI, and supports neuronal differentiation in the SVZ.

• Keywords
• Wnt signaling, adult neurogenesis, focal cerebral ischemia, gliogenesis, neural stem/progenitor cell, patch-clamp technique, single-cell RNA sequencing, transgenic mouse,
• Publication type
• Journal Article MeSH

Generation of neurons in the embryonic neocortex is a balanced process of proliferation and differentiation of neuronal progenitor cells. Canonical Wnt signalling is crucial for expansion of radial glial cells in the ventricular zone and for differentiation of intermediate progenitors in the subventricular zone. We detected abundant expression of two transcrtiption factors mediating canonical Wnt signalling, Tcf7L1 and Tcf7L2, in the ventricular zone of the embryonic neocortex. Conditional knock-out analysis showed that Tcf7L2, but not Tcf7L1, is the principal Wnt mediator important for maintenance of progenitor cell identity in the ventricular zone. In the absence of Tcf7L2, the Wnt activity is reduced, ventricular zone markers Pax6 and Sox2 are downregulated and the neuroepithelial structure is severed due to the loss of apical adherens junctions. This results in decreased proliferation of radial glial cells, the reduced number of intermediate progenitors in the subventricular zone and hypoplastic forebrain. Our data show that canonical Wnt signalling, which is essential for determining the neuroepithelial character of the neocortical ventricular zone, is mediated by Tcf7L2.

• Keywords
• Neocortex, Neurogenenesis, Tcf7L1, Tcf7L2, Wnt signalling,
• MeSH
• Cell Differentiation genetics   MeSH
• Chloride-Bicarbonate Antiporters MeSH
• Down-Regulation genetics   MeSH
• Embryo, Mammalian MeSH
• Hippocampus cytology   embryology   MeSH
• Mutation genetics   MeSH
• Mice, Transgenic MeSH
• Mice MeSH
• Neocortex cytology   embryology   MeSH
• Neural Stem Cells physiology   MeSH
• Neurogenesis physiology   MeSH
• Neuroglia MeSH
• Neurons physiology   MeSH
• Cell Count MeSH
• Cell Proliferation genetics   MeSH
• Transcription Factor 7-Like 2 Protein genetics   metabolism   MeSH
• T-Box Domain Proteins metabolism   MeSH
• Wnt Proteins metabolism   MeSH
• Retinal Ganglion Cells physiology   MeSH
• Signal Transduction genetics   MeSH
• SOXB1 Transcription Factors metabolism   MeSH
• Animals MeSH
• Check Tag
• Mice MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Chloride-Bicarbonate Antiporters MeSH
• Eomes protein, mouse MeSH Browser
• Transcription Factor 7-Like 2 Protein MeSH
• T-Box Domain Proteins MeSH
• Wnt Proteins MeSH
• Sox2 protein, mouse MeSH Browser
• Tcf7l2 protein, mouse MeSH Browser
• SOXB1 Transcription Factors MeSH