Academic literature on the topic 'Neurodifferentiation'

Background: Alzheimer’s disease (AD) is characterized by a progressive loss of episodic memory associated with amyloid-β peptide aggregation and the abnormal phosphorylation of the tau protein, leading to the loss of cholinergic function. Acetylcholinesterase (AChE) inhibitors are the main class of drugs used in AD therapy. Objective: The aim of the current study was to evaluate the potential of two tacrine-donepezil hybrid molecules (TA8Amino and TAHB3), which are AChE inhibitors, to induce neurodifferentiation and neuritogenesis in SH-SY5Y cells. Methods: The experiments were carried out to characterize neurodifferentiation, cellular changes related to responses to oxidative stress and pathways of cell survival in response to drug treatments. Results: The results indicated that the compounds did not present cytotoxic effects in SH-SY5Y or HepG2 cells. TA8Amino and TAHB3 induced neurodifferentiation and neuritogenesis in SH-SY5Y cells. These cells showed increased levels of intracellular and mitochondrial reactive oxygen species; the induction of oxidative stress was also demonstrated by an increase in SOD1 expression in TA8Amino and TAHB3-treated cells. Cells treated with the compounds showed an increase in PTEN(Ser380/Thr382/383) and AKT(Ser473) expression, suggesting the involvement of the AKT pathway. Conclusion: Our results demonstrated that TA8Amino and TAHB3 present advantages as potential drugs for AD therapy and that they are capable of inducing neurodifferentiation and neuritogenesis.

AbstractUnderstanding the mechanisms behind neurodifferentiation in adults will be an important milestone in our quest to identify treatment strategies for cognitive disorders observed during our natural ageing or disease. It is now clear that the maturation of neural stem cells to neurones, fully integrated into neuronal circuits requires a complete remodelling of cellular metabolism, including switching the cellular energy source. Mitochondria are central for this transition and are increasingly seen as the regulatory hub in defining neural stem cell fate and neurodevelopment. This review explores our current knowledge of metabolism during adult neurodifferentiation.

Recently, the scientific community has started to focus on the neurogenic potential of cannabinoids. The phytocompound cannabidiol (CBD) shows different mechanism of signaling on cannabinoid receptor 1 (CB1), depending on its concentration. In this study, we investigated if CBD may induce in vitro neuronal differentiation after treatment at 5 µM and 10 µM. For this purpose, we decided to use the spinal cord × neuroblastoma hybrid cell line (NSC-34) because of its proliferative and undifferentiated state. The messenger RNAs (mRNAs) expression profiles were tested using high-throughput sequencing technology and Western blot assay was used to determine the number of main proteins in different pathways. Interestingly, the treatment shows different genes associated with neurodifferentiation statistically significant, such as Rbfox3, Tubb3, Pax6 and Eno2. The CB1 signaling pathway is responsible for neuronal differentiation at 10 µM, as suggested by the presence of p-ERK and p-AKT, but not at 5 µM. A new correlation between CBD, neurodifferentiation and retinoic acid receptor-related orphan receptors (RORs) has been observed.

Recently FT-IR analysis has been employed to study changes in molecular signatures during embryonic stem cell differentiation. We were interested to find out whether FT-IR spectroscopy could be applied to analyze changes in human skin mesenchymal stem cell (S-MSC) biochemical profile duringin vitroneurodifferentiation. S-MSCs were propagated in serum-free medium with EGF and FGF-2 during six weeks. Neural progenitor cell line ReNcell CX (Millipore) was used as a reference cell line. Samples were collected each week and analyzed for neural marker nestin, tubulinβIII, GFAP, and CD271 expression. FT-IR analysis was carried out using microplate reader HTS-XT (Bruker, Germany). Despite the immunophenotype similarity, FT-IR spectroscopy revealed distinct profiles for S-MSC culture and ReNcell CX cells. FT-IR spectra analyses showed changes of protein and lipid concentration during neurodifferentiation and different carbohydrate composition in ReNcell CX and S-MSCs. It was possible to discriminate between S-MSC cultures at different time points during neurodifferentiation. The results of this study demonstrate that FT-IR spectroscopy is more sensitive than conventional immunophenotyping analysis and it has a great potential for the monitoring of the stem cell differentiation status.

The present study proposes a clarification on the molecular mechanism by which ganglioside GM1 promotes neurodifferentiation, demonstrating in vitro that neurotrophic functions are exerted by an interaction between the oligosaccharide portion (OligoGM1) and an extracellular domain of TrkA receptor. Similarly to the entire molecule, the oligosaccharide portion of ganglioside GM1, rather than ceramide, is responsible for neurodifferentiation by augmenting neurite elongation and by increasing the expression of neurofilament proteins in mouse neuroblastoma cell line Neuro2a (N2a). Conversely, the single components of OligoGM1 (asialo-OligoGM1, OligoGM2, OligoGM3, sialic acid or galactose) are not able to induce a neuro-like morphology. The neurodifferentiative effect is exerted instead by fucosyl-OligoGM1. Contrarily to GM1, exogenous OligoGM1 never integrates in the plasma membrane composition and does not belong to the intracellular metabolism: the unique interaction with N2a is characterized by a weak non-covalent association to the plasma membrane that suggests the existence of an OligoGM1-stimulated target on the cell surface. In fact, the neurotrophic properties of GM1 oligosaccharide are exerted by activating TrkA receptor and the following cascade leading to neurodifferentiation event. The second part of this study elucidates the interaction between GM1 and TrkA, revealing a direct association of OligoGM1 to an extracellular domain of the receptor. Photolabeling experiments, performed employing nitrogen azide radiolabeled GM1 derivatives, show a direct association of the oligosaccharide chain to TrkA. Moreover, a bioinformatics study reveals that OligoGM1 fits perfectly in a pocket of the TrkA-NGF complex, stabilizing and favoring their intermolecular interactions as revealed by the increase in energy associated to the new complex TrkA-NGF-OligoGM1. A precise molecular recognition process between OligoGM1 and a specific extracellular domain of the TrkA receptor is supposed. According to the weak association of OligoGM1 to the cell surface, no covalent bounds between OligoGM1 and TrkA-NGF complex were found. For the first time the molecular mechanism by which GM1 exerts its neurodifferentiative potential was identified, finding out a direct interaction between the oligosaccharide portion and an extracellular domain of TrkA receptor responsible for enhancing the signal transduction related to the neurodifferentiation pathway.

Il ganglioside GM1 è un glicosfingolipide mono-sialilato presente nello strato esterno della membrana plasmatica cellulare ed è particolarmente abbondante nei neuroni. Numerosi studi in vitro e in vivo evidenziano il ruolo del GM1 non solo come componente strutturale ma anche come regolatore di diversi processi cellulari. Infatti, l'arricchimento di GM1 nei microdomini di membrana promuove il differenziamento e la protezione neuronale. Inoltre il contenuto di GM1 è essenziale per la sopravvivenza e il mantenimento dei neuroni. Nonostante vi siano numerose evidenze sugli effetti neuronotrofici mediati dal GM1, la conoscenza del meccanismo d'azione sottostante è scarsa. Recentemente, la catena oligosaccaridica del GM1 (oligoGM1) è stata identificata come responsabile delle proprietà neuritogeniche del ganglioside GM1 nelle cellule di neuroblastoma. Gli effetti mediati dall’oligoGM1 dipendono dal suo legame con il recettore specifico dell’ NGF, il TrkA, determinando così l'attivazione della via TrkA-MAPK. In questo contesto, il mio lavoro di dottorato mirava a confermare il ruolo dell’oligoGM1, come componente bioattiva dell’intero ganglioside GM1, capace di stimolare i processi di differenziaziamento e maturazione dei neuroni granulari cerebellari di topo. Come prima cosa, abbiamo eseguito analisi morfologiche in time -course sui neuroni primari coltivati in presenza o in assenza dei gangliosidi GM1 o GD1a (il quale rappresenta il diretto precursore catabolico del GM1), somministrati esogenamente. Abbiamo osservato che entrambi i gangliosidi aumentavano l’aggregazione e l'arborizzazione dei neuroni. Dopo successiva somministrazione dei rispettivi oligosaccaridi, abbiamo osservato che solo l’oligoGM1 favoriva la migrazione dei neuroni, mentre l’oligoGD1a non induceva nessun effetto discriminante rispetto alle cellule controllo. Questo risultato suggerisce l'importanza della specifica struttura saccaridica del GM1 nella mediazione degli effetti neuronotrofici del ganglioside. Quindi abbiamo caratterizzato biochimicamente l'effetto mediato dall’oligoGM1 nei neuroni e abbiamo osservato un più elevato tasso di fosforilazione delle proteine FAK e Src, le quali rappresentano i regolatori intracellulari chiave della motilità neuronale. Inoltre, in presenza dell’ oligoGM1 i neuroni granulari cerebellari mostravano un aumento del livello di marcatori neuronali specifici (ad es. β3-Tubulina, Tau, Neuroglicano C, Sinapsina), suggerendo uno stadio di maturazione più avanzato rispetto ai controlli. Inoltre, abbiamo scoperto che l'oligoGM1 accelera l'espressione del pattern di gangliosidi tipico dei neuroni maturi che è caratterizzato da alti livelli di gangliosidi complessi (cioè GM1, GD1a, GD1b e GT1b) e basso livello del ganglioside più semplice GM3. Per studiare il meccanismo d'azione dell'oligoGM1, abbiamo usato il suo derivato marcato con il trizio e abbiamo scoperto che l'oligoGM1 interagisce con la superficie cellulare senza entrare nelle cellule. Questa scoperta suggerisce la presenza di un bersaglio biologico sulla membrana plasmatica neuronale. È interessante notare che abbiamo riscontrato una precoce attivazione della via di segnalazione del TrkA associata alle MAP chinasi in seguito alla somministrazione dell’oligoGM1 nelle culture neuronali. Questo risultato suggerisce che questo evento rappresenti un punto di partenza degli effetti dell’ oligoGM1 nei neuroni. I nostri dati rivelano che gli effetti del ganglioside GM1 sul differenziamento e la maturazione neuronale sono mediati dalla sua porzione di oligosaccaride. Infatti, l’oligoGM1 interagisce con la superficie cellulare, innescando così l'attivazione di processi biochimici intracellulari che sono responsabili della migrazione neuronale, dell'emissione dei dendriti e della crescita degli assoni. Nel complesso, i nostri risultati sottolineano l'importanza dell’ oligoGM1 come un nuovo e promettente fattore neurotrofico.
The GM1 ganglioside is a mono-sialylated glycosphingolipid present in the outer layer of the cell plasma membrane and abundant in neurons. Numerous in vitro and in vivo studies highlight the role of GM1 not only as a structural component but also as a functional regulator. Indeed, GM1 enrichment in membrane microdomains promotes neuronal differentiation and protection, and the GM1 content is essential for neuronal survival and maintenance. Despite many lines of evidence on the GM1-mediated neuronotrophic effects, our knowledge on the underlying mechanism of action is scant. Recently, the oligosaccharide chain of GM1 (oligoGM1) has been identified as responsible for the neuritogenic properties of the GM1 ganglioside in neuroblastoma cells. The oligoGM1-mediated effects depend on its binding to the NGF specific receptor TrkA, thus resulting in the TrkA-MAPK pathway activation. In this context, my PhD work aimed to confirm the role of the oligoGM1, as the bioactive portion of the entire GM1 ganglioside, capable of enhancing the differentiation and maturation processes of mouse cerebellar granule neurons. First, we performed time course morphological analyses on mouse primary neurons plated in the presence or absence of exogenously administered gangliosides GM1 or GD1a (direct GM1 catabolic precursor). We found that both gangliosides increased neuron clustering and arborization, however only oligoGM1 and not oligoGD1a induced the same effects in prompting neuron migration. This result suggests the importance of the specific GM1 saccharide structure in mediating neuronotrophic effects. Then we characterized biochemically the oligoGM1-mediated effect in mouse primary neurons, and we observed a higher phosphorylation rate of FAK and Src proteins which are the intracellular key regulators of neuronal motility. Moreover, in the presence of oligoGM1 cerebellar granule neurons showed increased level of specific neuronal markers (e.g., β3-Tubulin, Tau, Neuroglycan C, Synapsin), suggesting an advanced stage of maturation compared to controls. In addition, we found that the oligoGM1 accelerates the expression of the typical ganglioside pattern of mature neurons which is characterized by high levels of complex gangliosides (i.e., GM1, GD1a, GD1b, and GT1b) and low level of the simplest one, the GM3 ganglioside. To study the mechanism of action of the oligoGM1, we used its tritium labeled derivative and we found that the oligoGM1 interacts with the cell surface without entering the cells. This finding suggests the presence of a biological target at the neuronal plasma membrane. Interestingly, we observed the TrkA-MAP kinase pathway activation as an early event underlying oligoGM1 effects in neurons. Our data reveal that the effects of GM1 ganglioside on neuronal differentiation and maturation are mediated by its oligosaccharide portion. Indeed, oligoGM1 interacts with the cell surface, thus triggering the activation of intracellular biochemical pathways that are responsible for neuronal migration, dendrites emission and axon growth. Overall, our results point out the importance of oligoGM1 as a new promising neurotrophic player.

It has been already demonstrated that the oligosaccharide chain (OligoGM1) of the ganglioside GM1, β-Gal-(1-3)-β-GalNAc-(1-4)-[α-Neu5Ac-(2-3)]-β-Gal-(1-4)-β-Glc-(1-1)-Ceramide, promotes neurodifferentiation in the Neuro2a murine neuroblastoma cells, used as a model, by directly interacting with the NGF specific receptor TrkA, leading to the activation of ERK1/2 downstream pathway. In this context, my PhD work aimed to investigate which other biochemical pathways, in addition to TrkA-MAPK cascade activation, are prompted by OligoGM1, with an emphasis on Ca2+ modulating factors. A proteomic analysis (nLC-ESi-MS-MS) performed on Neuro2a cells treated with 50 µM OligoGM1 for 24 hours led to the identification and quantification of 324 proteins exclusively expressed by OligoGM1-treated cells. Interestingly, some of these proteins are involved in the regulation of Ca2+ homeostasis and in Ca2+-dependent differentiative pathways. In order to evaluate if OligoGM1 administration was able to modulate Ca2+ flow, we performed calcium-imaging experiments on Neuro2a cells using the Ca2+-sensitive Fluo-4 probe. Starting from 5 minutes upon OligoGM1 administration to undifferentiated Neuro2a, a significant increase in Ca2+ influx occurs. At the same time an increased activation of TrkA membrane receptor was observed and, importantly, the addition of a specific TrkA inhibitor abolished the OligoGM1 mediated increase of the cytosolic Ca2+, suggesting that the opening of the cell Ca2+ channels following OligoGM1 administration depends on the activation of TrkA receptor. To unveil which cellular pathway activated by OligoGM1 could lead to the increase of intracellular Ca2+, time-course immunoblotting analyses were performed. The data revealed that following TrkA activation, OligoGM1 induced the activation of phospholipase PLCγ1 which converts phosphatidylinositol 4,5-bisphosphate (PIP2) to diacyglycerol (DAG) and inositol 1,4,5-trisphosphate (IP3), the second messengers that propagate cellular signalling via Ca2+ mobilization. Moreover, we observed a hyperphosphorylation of the DAG substrate, protein kinase C (PKC), which is a priming event that enables its catalytic activation in response to lipid second messengers, and we found its enrichment in lipid rafts, events that consolidate its activation. When calcium-imaging experiments where performed in the presence of xestospongin C, a potent inhibitor of IP3 receptors on endoplasmic reticulum, a reduction of about 50% of Ca2+ influx was observed, suggesting that the Ca2+ flows moved by the OligoGM1 come not only from intracellular storages, but probably also from the extracellular environment. Accordingly, in the presence of both extracellular (EGTA) and intracellular (BAPTA-AM) Ca2+ chelators the neuritogenic effect induced by OligoGM1 was abolished. The work described in this thesis confirms that the effects of GM1 ganglioside on neuronal differentiation are mediated by its oligosaccharide portion. In particular, here I highlight that the oligosaccharide, initiating a signalling cascade on the cell surface, is responsible alone for the balancing of the intracellular Ca2+ levels that underlie neurite sprouting, which have historically been attributed to the whole GM1 ganglioside and its role as lipid inserted into the plasma membrane. In this way, these data give additional information on the molecular characterization of the mechanisms by which GM1 exerts its neuronal functions.

碩士
國立臺灣大學
臨床牙醫學研究所
100
Aim：Both Stem cells from human exfoliated deciduous teeth (SHED) and Stem cells from apical papilla (SCAP) are multipotent stem cells. After neural induction, these two kinds of cells could be differentiated into neuron like cells. We hypothesized that SHED and SCAP have the same neurodifferentiation potentials. The purpose of this study is to compare the differences of neurodifferentiation potentials of SHED and SCAP. Materials and Methods：We cultivated SHED and SCAP in neural induction medium for 0 day, 1 day ,3 days, 7 days , 14 days and 21 days and analyzed cell morphology, cell proliferation, gene expression patterns(RT-PCR) and immunofluorescence before and after differentiation. Results：After 3 days cultivation in neural induction medium, the morphology of SHED and SCAP were changed to neuron like cells. We found that cell proliferation of SHED and SCAP were reduced. After 7 days cultivation in neural induction medium, gene expression patterns (RT-PCR) and Immunofluorescence analysis of the expression Neurofilament demonstrated that both SHED and SCAP were successfully differentiate into neuron cells. However, the Neurofilament gene expression of inducted SCAP was much upregulated then that of inducted SHED. This result indicated that the neurodifferentiation potential of SCAP is higher than that of SHED. Conclusion ：Although both SHED and SCAP have potentials for neurodifferentiation but neurodifferentiation potential of SCAP is much better than that of SHED. We can expect that by using SCAP for neurogenesis would get better results.