SummaryThe regulation of the proliferation and polarity of neural progenitors is crucial for the development of the brain cortex. Animal studies have implicated glycogen synthase kinase 3 (GSK3) as a pivotal regulator of both proliferation and polarity, yet the functional relevance of its signaling for the unique features of human corticogenesis remains to be elucidated. We harnessed human cortical brain organoids to probe the longitudinal impact of GSK3 inhibition through multiple developmental stages. Chronic GSK3 inhibition increased the proliferation of neural progenitors and caused massive derangement of cortical tissue architecture. Single-cell transcriptome profiling revealed a direct impact on early neurogenesis and uncovered a selective role of GSK3 in the regulation of glutamatergic lineages and outer radial glia output. Our dissection of the GSK3-dependent transcriptional network in human corticogenesis underscores the robustness of the programs determining neuronal identity independent of tissue architecture.
Amyloid precursor protein (APP) is implicated in neural development as well as in the pathology of Alzheimer's disease (AD); however, its biological function still remains unclear. It has been reported that APP stimulates the proliferation and neuronal differentiation of neural stem cells (NSCs), while other studies suggest an important effect enhancing gliogenesis in NSCs. As expected, APP protein/mRNA is detected in hNS1 cells, a model cell line of human NSCs, both under proliferation and throughout the differentiation period. To investigate the potential function that APP plays in cell fate specification and differentiation of hNS1 cells, we transiently increased human APP levels in these cells and analyzed its cell intrinsic effects. Our data indicate that increased levels of APP induce early cell cycle exit and instructively direct hNS1 cell fate towards a glial phenotype, while decreasing neuronal differentiation. Since elevated APP levels also enhanced APP intracellular domain (AICD)-immunoreactivity, these effects could be, in part, mediated by the APP/AICD system. The AICD domain can play a potential role in signal transduction by its molecular interaction with different target genes such as GSK3B, whose expression was also increased in APP-overexpressing cells that, in turn, may contribute to promoting gliogenesis and inhibiting neurogenesis in NSCs. These data suggest an important action of APP in modulating hNSCs differentiation (probably in an AICD-GSK-3β-dependent manner) and may thus be important for the future development of stem cell therapy strategies for the diseased mammalian brain.
The amyloid -β peptide (Aβ) is the main component of the amyloid plaques in Alzheimer's disease (AD). It has been widely demonstrated that Aβ is toxic to neurons and is associated with AD pathology. However, Aβ also appears to have an important biological function both in the adult brain and throughout embryonic development of the nervous system, acting as a trophic factor at low concentrations.It is known that Neural Stem Cells (NSCs) are capable of self-renewal and differentiate into functional glial and neuronal cells. Therefore, human NSCs may be a hope for future therapeutic application in neurodegenerative diseases such as AD. The effects of Aβ peptides on NSCs are still not well understood and remain controversial.In this chapter we outline the materials and methods used for the culture and differentiation of hNS1 cells, a cell line of human NSCs. We describe the preparation of different forms (monomeric, oligomeric and fibrillary) of Aβ peptide and subsequent cell treatment, followed by the analysis of the effects on toxicity, cell proliferation and cell fate specification of hNS1 cells.
The regulation of proliferation and polarity of neural progenitors is crucial for the development of the brain cortex, with modes and timings of cell division intimately related to the stereotypical acquisition of layerspecific neuronal identities. Animal studies have implicated glycogen synthase kinase 3 (GSK3) as a pivotal regulator of both proliferation and polarity, yet the functional relevance of its signaling for the unique features of human corticogenesis remain to be elucidated. Here we harness human cortical brain organoids to probe the longitudinal impact of GSK3 inhibition through multiple developmental stages. Our results indicate that chronic GSK3 inhibition increases the proliferation of neural progenitors and causes massive derangement of cortical tissue architecture. Surprisingly, single cell transcriptome profiling revealed only a discrete impact on early neurogenesis and uncovered a pivotal role of GSK3 in the regulation of NEUROD1/2 lineages and outer radial glia (oRG) output, without compromising direct neurogenic trajectories. Through this first single cell-level dissection of the GSK3 regulatory network in human corticogenesis, our work underscores the robustness of transcriptional programs in determining neuronal identity independent of tissue architecture. IntroductionNeurogenesis is initiated by the formation of a neuroepithelium, composed by neural stem cells (NSCs) organized in apico-basal orientation that divide symmetrically leading to a rapid expansion of the NSC pool (Taverna et al., 2014;Temple, 2003). The polarization of the neuroepithelium precedes the differentiation of NSCs into radial glia cells (RGCs), and triggers the elongation of cytoplasmic processes that form a migratory scaffold for newborn neurons (Betizeau et al., 2013). Such polarization is in turn necessary for the acquisition of the key properties that define tissue organization (Johansson et al., 2010).Glycogen synthase kinase 3 alfa and beta (GSK3 and ) are serine/threonine kinases encoded by 2 different genes, which function as integrating hubs for multiple proliferation and differentiation signals due to their central role in the receptor tyrosine kinase, Wnt and sonic hedgehog signaling pathways McCubrey et al., 2016). GSK3 is involved in neurodevelopment through the phosphorylation of a broad set of substrates, including transcription factors essential for brain development, such as CREB (Grimes and Jope, 2001a), neurogenin2 (Ma et al., 2008) β-catenin (Aberle et al., 1997 and multiple microtubule-associated proteins (Fumoto et al., 2008;Zhou et al., 2004). Studies in animal models have provided a wealth of evidence linking GSK3 activity to the regulation of early and late neurogenesis in a stage-wise fashion. Its activity is required to maintain the overall polarity of the radial glia scaffold (Yokota et al., 2010). Genetic ablation of both GSK3 or GSK3 in radial glial cells (RGCs) results in a massive increase in neural progenitor proliferation with marked suppression of intermediate progenitor cells (...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.