TRPM4 inhibition slows neuritogenesis progression of cortical neurons.

TRPM4 is a non-selective cation channel activated by intracellular Ca2+ but only permeable to monovalent cations, its activation regulates membrane potential and intracellular calcium. This channel participates in the migration and adhesion of non-excitable cells and forms an integral part of the focal adhesion complex. In neurons, TRPM4 expression starts before birth and its function at this stage is not clear, but it may function in processes such as neurite development. Here we investigate the role of TRPM4 in neuritogenesis. We found that neurons at DIV 0 express TRPM4, the inhibition of TRPM4 using 9-Ph reduces neurite number and slows the progression of neurite development, keeping neurons in stage 1. The genetic suppression of TRPM4 using an shRNA at later stages (DIV2) reduces neurite length. Conversely, at DIV 0, TRPM4 inhibition augments the Cch-induced Ca2 + i increase, altering the calcium homeostasis. Together, these results show that TRPM4 participates in progression of neurite development and suggest a critical role of the calcium modulation during this stage of neuronal development.

Sodium Tungstate Promotes Neurite Outgrowth and Confers Neuroprotection in Neuro2a and SH-SY5Y Cells.

Sodium tungstate (Na2WO4) normalizes glucose metabolism in the liver and muscle, activating the Mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK) pathway. Because this pathway controls neuronal survival and differentiation, we investigated the effects of Na2WO4 in mouse Neuro2a and human SH-SY5Y neuroblastoma monolayer cell cultures. Na2WO4 promotes differentiation to cholinergic neurites via an increased G1/G0 cell cycle in response to the synergic activation of the Phosphatidylinositol 3-kinase (PI3K/Akt) and ERK1/2 signaling pathways. In Neuro2a cells, Na2WO4 increases protein synthesis by activating the mechanistic target of rapamycin (mTOR) and S6K kinases and GLUT3-mediated glucose uptake, providing the energy and protein synthesis needed for neurite outgrowth. Furthermore, Na2WO4 increased the expression of myocyte enhancer factor 2D (MEF2D), a member of a family of transcription factors involved in neuronal survival and plasticity, through a post-translational mechanism that increases its half-life. Site-directed mutations of residues involved in the sumoylation of the protein abrogated the positive effects of Na2WO4 on the MEF2D-dependent transcriptional activity. In addition, the neuroprotective effects of Na2WO4 were evaluated in the presence of advanced glycation end products (AGEs). AGEs diminished neurite differentiation owing to a reduction in the G1/G0 cell cycle, concomitant with lower expression of MEF2D and the GLUT3 transporter. These negative effects were corrected in both cell lines after incubation with Na2WO4. These findings support the role of Na2WO4 in neuronal plasticity, albeit further experiments using 3D cultures, and animal models will be needed to validate the therapeutic potential of the compound.

Nuclear Magnetic Resonance Treatment Induces ßNGF Release from Schwann Cells and Enhances the Neurite Growth of Dorsal Root Ganglion Neurons In Vitro.

Peripheral nerve regeneration depends on close interaction between neurons and Schwann cells (SCs). After nerve injury, SCs produce growth factors and cytokines that are crucial for axon re-growth. Previous studies revealed the supernatant of SCs exposed to nuclear magnetic resonance therapy (NMRT) treatment to increase survival and neurite formation of rat dorsal root ganglion (DRG) neurons in vitro. The aim of this study was to identify factors involved in transferring the observed NMRT-induced effects to SCs and consequently to DRG neurons. Conditioned media of NMRT-treated (CM NMRT) and untreated SCs (CM CTRL) were tested by beta-nerve growth factor (ßNGF) ELISA and multiplex cytokine panels to profile secreted factors. The expression of nociceptive transient receptor potential vanilloid 1 (TRPV1) channels was assessed and the intracellular calcium response in DRG neurons to high-potassium solution, capsaicin or adenosine triphosphate was measured mimicking noxious stimuli. NMRT induced the secretion of ßNGF and pro-regenerative-signaling factors. Blocking antibody experiments confirmed ßNGF as the main factor responsible for neurotrophic/neuritogenic effects of CM NMRT. The TRPV1 expression or sensitivity to specific stimuli was not altered, whereas the viability of cultured DRG neurons was increased. Positive effects of CM NMRT supernatant on DRG neurons are primarily mediated by increased ßNGF levels.

Evaluation of a Synthetic Retinoid, Ellorarxine, in the NSC-34 Cell Model of Motor Neuron Disease.

Amyotrophic lateral sclerosis (ALS) is the most common motor neuron disease worldwide and is characterized by progressive muscle atrophy. There are currently two approved treatments, but they only relieve symptoms briefly and do not cure the disease. The main hindrance to research is the complex cause of ALS, with its pathogenesis not yet fully elucidated. Retinoids (vitamin A derivatives) appear to be essential in neuronal cells and have been implicated in ALS pathogenesis. This study explores 4-[2-(5,5,8,8-tetramethyl-5,6,7,8-tetrahydroquinoxalin-2-yl)ethylnyl]benzoic acid (Ellorarxine, or DC645 or NVG0645), a leading synthetic retinoic acid, discussing its pharmacological mechanisms, neuroprotective properties, and relevance to ALS. The potential therapeutic effect of Ellorarxine was analyzed in vitro using the WT and SOD1G93A NSC-34 cell model of ALS at an administered concentration of 0.3-30 nM. Histological, functional, and biochemical analyses were performed. Elorarxine significantly increased MAP2 expression and neurite length, increased AMPA receptor GluA2 expression and raised intracellular Ca2+ baseline, increased level of excitability, and reduced Ca2+ spike during depolarization in neurites. Ellorarxine also displayed both antioxidant and anti-inflammatory effects. Overall, these results suggest Ellorarxine shows relevance and promise as a novel therapeutic strategy for treatment of ALS.

Transcriptome Profiling of Phenylalanine-Treated Human Neuronal Model: Spotlight on Neurite Impairment and Synaptic Connectivity.

Phenylketonuria (PKU) is the most common inherited disorder of amino acid metabolism, characterized by high levels of phenylalanine (Phe) in the blood and brain, leading to cognitive impairment without treatment. Nevertheless, Phe-mediated brain dysfunction is not fully understood. The objective of this study was to address gene expression alterations due to excessive Phe exposure in the human neuronal model and provide molecular advances in PKU pathophysiology. Hence, we performed NT2/D1 differentiation in culture, and, for the first time, we used Phe-treated NT2-derived neurons (NT2/N) as a novel model for Phe-mediated neuronal impairment. NT2/N were treated with 1.25 mM, 2.5 mM, 5 mM, 10 mM, and 30 mM Phe and subjected to whole-mRNA short-read sequencing. Differentially expressed genes (DEGs) were analyzed and enrichment analysis was performed. Under three different Phe concentrations (2.5 mM, 5 mM, and 10 mM), DEGs pointed to the PREX1, LRP4, CDC42BPG, GPR50, PRMT8, RASGRF2, and CDH6 genes, placing them in the context of PKU for the first time. Enriched processes included dendrite and axon impairment, synaptic transmission, and membrane assembly. In contrast to these groups, the 30 mM Phe treatment group clearly represented the neurotoxicity of Phe, exhibiting enrichment in apoptotic pathways. In conclusion, we established NT2/N as a novel model for Phe-mediated neuronal dysfunction and outlined the Phe-induced gene expression changes resulting in neurite impairment and altered synaptic connectivity.

Dipeptidyl Peptidase (DPP)-4 Inhibitors and Pituitary Adenylate Cyclase-Activating Polypeptide, a DPP-4 Substrate, Extend Neurite Outgrowth of Mouse Dorsal Root Ganglia Neurons: A Promising Approach in Diabetic Polyneuropathy Treatment.

Individuals suffering from diabetic polyneuropathy (DPN) experience debilitating symptoms such as pain, paranesthesia, and sensory disturbances, prompting a quest for effective treatments. Dipeptidyl-peptidase (DPP)-4 inhibitors, recognized for their potential in ameliorating DPN, have sparked interest, yet the precise mechanism underlying their neurotrophic impact on the peripheral nerve system (PNS) remains elusive. Our study delves into the neurotrophic effects of DPP-4 inhibitors, including Diprotin A, linagliptin, and sitagliptin, alongside pituitary adenylate cyclase-activating polypeptide (PACAP), Neuropeptide Y (NPY), and Stromal cell-derived factor (SDF)-1a-known DPP-4 substrates with neurotrophic properties. Utilizing primary culture dorsal root ganglia (DRG) neurons, we meticulously evaluated neurite outgrowth in response to these agents. Remarkably, all DPP-4 inhibitors and PACAP demonstrated a significant elongation of neurite length in DRG neurons (PACAP 0.1 µM: 2221 ± 466 µm, control: 1379 ± 420, p < 0.0001), underscoring their potential in nerve regeneration. Conversely, NPY and SDF-1a failed to induce neurite elongation, accentuating the unique neurotrophic properties of DPP-4 inhibition and PACAP. Our findings suggest that the upregulation of PACAP, facilitated by DPP-4 inhibition, plays a pivotal role in promoting neurite elongation within the PNS, presenting a promising avenue for the development of novel DPN therapies with enhanced neurodegenerative capabilities.

Nogo Receptor Antagonist LOTUS Promotes Neurite Outgrowth through Its Interaction with Teneurin-4.

Neurite outgrowth is a crucial process for organizing neuronal circuits in neuronal development and regeneration after injury. Regenerative failure in the adult mammalian central nervous system (CNS) is attributed to axonal growth inhibitors such as the Nogo protein that commonly binds to Nogo receptor-1 (NgR1). We previously reported that lateral olfactory tract usher substance (LOTUS) functions as an endogenous antagonist for NgR1 in forming neuronal circuits in the developing brain and improving axonal regeneration in the adult injured CNS. However, another molecular and cellular function of LOTUS remains unknown. In this study, we found that cultured retinal explant neurons extend their neurites on the LOTUS-coating substrate. This action was also observed in cultured retinal explant neurons derived from Ngr1-deficient mouse embryos, indicating that the promoting action of LOTUS on neurite outgrowth may be mediated by unidentified LOTUS-binding protein(s). We therefore screened the binding partner(s) of LOTUS by using a liquid chromatography-tandem mass spectrometry (LC-MS/MS). LC-MS/MS analysis and pull-down assay showed that LOTUS interacts with Teneurin-4 (Ten-4), a cell adhesion molecule. RNAi knockdown of Ten-4 inhibited neurite outgrowth on the LOTUS substrate in retinoic acid (RA)-treated Neuro2A cells. Furthermore, a soluble form of Ten-4 attenuates the promoting action on neurite outgrowth in cultured retinal explant neurons on the LOTUS substrate. These results suggest that LOTUS promotes neurite outgrowth by interacting with Ten-4. Our findings may provide a new molecular mechanism of LOTUS to contribute to neuronal circuit formation in development and to enhance axonal regeneration after CNS injury.

l-DOPA receptor GPR143 inhibits neurite outgrowth via L-type calcium channels in PC12 cells.

The gene product of ocular albinism 1 (OA1)/G-protein-coupled receptor (GPR)143 is a receptor for L-3,4-dihydroxyphenylanine (l-DOPA), the most effective agent for Parkinson's disease. When overexpressed, human wild-type GPR143, but not its mutants, inhibits neurite outgrowth in PC12 cells. We investigated the downstream signaling pathway for GPR143-induced inhibition of neurite outgrowth. Nifedipine restored GPR143-induced neurite outgrowth inhibition to the level of control transfectant but did not affect outgrowth in GPR143-knockdown cells. Cilnidipine and flunarizine also suppressed the GPR143-induced inhibition, but their effects at higher concentrations still occurred even in GPR143-knockdown cells. These results suggest that GPR143 regulates neurite outgrowth via L-type calcium channel(s).

Olanzapine attenuates amyloid-ß-induced microglia-mediated progressive neurite lesions.

The accumulation of amyloid-ß (Aß) in the brain is the first pathological mechanism to initiate Alzheimer's disease (AD) pathogenesis. However, the precise role of Aß in the disease progression remains unclear. Through decades of research, prolonged inflammation has emerged as an important core pathology in AD. Previously, a study has demonstrated the neurotoxic effect of Aß-induced neuroinflammation in neuron-glia co-culture at 72 h. Here, we hypothesise that initial stage Aß may trigger microglial inflammation, synergistically contributing to the progression of neurite lesions relevant to AD progression. In the present study, we aimed to determine whether olanzapine, an antipsychotic drug possessing anti-inflammatory properties, can ameliorate Aß-induced progressive neurite lesions. Our study reports that Aß induces neurite lesions with or without inflammatory microglial cells in vitro. More intriguingly, the present study revealed that Aß exacerbates neurite lesions in synergy with microglia. Moreover, the time course study revealed that Aß promotes microglia-mediated neurite lesions by eliciting the secretion of pro-inflammatory cytokines. Furthermore, our study shows that olanzapine at lower doses prevents Aß-induced microglia-mediated progressive neurite lesions. The increase in pro-inflammatory cytokines induced by Aß is attenuated by olanzapine administration, associated with a reduction in microglial inflammation. Finally, this study reports that microglial senescence induced by Aß was rescued by olanzapine. Thus, our study provides the first evidence that 1 µM to 5 µM of olanzapine can effectively prevent Aß-induced microglia-mediated progressive neurite lesions by modulating microglial inflammation. These observations reinforce the potential of targeting microglial remodelling to slow disease progression in AD.

Particulate matter constituents trigger the formation of extracellular amyloid ß and Tau -containing plaques and neurite shortening in vitro.

Air pollution is an environmental factor associated with an increased risk of neurodegenerative diseases, such as Alzheimer's and Parkinson's, characterized by decreased cognitive abilities and memory. The limited models of sporadic Alzheimer's disease fail to replicate all pathological hallmarks of the disease, making it challenging to uncover potential environmental causes. Environmentally driven models of Alzheimer's disease are thus timely and necessary. We used live-cell confocal fluorescent imaging combined with high-resolution stimulated emission depletion (STED) microscopy to follow the response of retinoic acid-differentiated human neuroblastoma SH-SY5Y cells to nanomaterial exposure. Here, we report that exposure of the cells to some particulate matter constituents reproduces a neurodegenerative phenotype, including extracellular amyloid beta-containing plaques and decreased neurite length. Consistent with the existing in vivo research, we observed detrimental effects, specifically a substantial reduction in neurite length and formation of amyloid beta plaques, after exposure to iron oxide and diesel exhaust particles. Conversely, after exposure to engineered cerium oxide nanoparticles, the lengths of neurites were maintained, and almost no extracellular amyloid beta plaques were formed. Although the exact mechanism behind this effect remains to be explained, the retinoic acid differentiated SH-SY5Y cell in vitro model could serve as an alternative, environmentally driven model of neurodegenerative diseases, including Alzheimer's disease.

PACAP glycosides promote cell outgrowth in vitro and reduce infarct size after stroke in a preclinical model.

Pituitary Adenylate Cyclase Activating Polypeptide (PACAP) is a pleiotropic peptide known to promote many beneficial processes following neural damage and cell death after stroke. Despite PACAP's known neurotrophic and anti-inflammatory properties, it has not realized its translational potential due to a poor pharmacokinetic profile (non-linear PK/PD), and limited Blood-Brain Barrier Penetration (BBB) permeability. We have previously shown that glycosylation of PACAP increases stability and enhances BBB penetration. In addition, our prior studies showed reduced neuronal cell death and neuroinflammation in models of Parkinson's disease and Traumatic Brain Injury (TBI). In this study we show that a PACAP(1-27) glucoside retains the known neurotrophic activity of native PACAP(1-27)in vitro and a 5-day daily treatment regimen (100 nM) leads to neurite-like extensions in PC12 cells. In addition, we show that intraperitoneal injection of a PACAP(1-27) lactoside (10 mg/kg) with improved BBB-penetration, given 1-hour after reperfusion in a Transient Middle Cerebral Artery Occlusion (tMCAO) mouse model, reduces the infarct size after the ischemic injury in males significantly by âˆ¼ 36 %, and the data suggest a dose-dependency. In conclusion, our data support further development of PACAP glycopeptides as promising novel drug candidates for the treatment of stroke, an area with an urgent clinical need.

Neurite outgrowth promotion in PC12 cells by 24(R)-ethyllophenol from Morus alba.

We examined the mechanism by which 24(R)-ethyllophenol (MAB28) isolated from the branches of Morus alba caused neurite outgrowth in rat pheochromocytoma cells (PC12). MAB28 significantly promoted neurite outgrowth to a similar degree as the positive control, nerve growth factor (NGF). After incubation with MAB28 in PC12 cells, phosphorylation of extracellular signal-regulated kinase, p38 mitogen-activated protein kinase, and cyclic AMP response element-binding protein was detected, but the time course of phosphorylation was different from that induced by NGF. The expression of chloride intracellular channel protein 3 (CLIC3) was significantly decreased by MAB28. 5-Nitro-2-(3-phenylpropylamino)-benzoic acid (NPPB), an outward rectifying chloride channel inhibitor, significantly promoted neurite outgrowth in PC12 cells. These data suggested that MAB28 could induce neurite outgrowth by downregulating CLIC3 expression.

Asporin and CD109, expressed in the injured neonatal spinal cord, attenuate axonal re-growth in vitro.

Axonal regeneration is restricted in adults and causes irreversible motor dysfunction following spinal cord injury (SCI). In contrast, neonates have prominent regenerative potential and can restore their neural function. Although the distinct cellular responses in neonates have been studied, how they contribute to neural recovery remains unclear. To assess whether the secreted molecules in neonatal SCI can enhance neural regeneration, we re-analyzed the previously performed single-nucleus RNA-seq (snRNA-seq) and focused on Asporin and Cd109, the highly expressed genes in the injured neonatal spinal cord. In the present study, we showed that both these molecules were expressed in the injured spinal cords of adults and neonates. We treated the cortical neurons with recombinant Asporin or CD109 to observe their direct effects on neurons in vitro. We demonstrated that these molecules enhance neurite outgrowth in neurons. However, these molecules did not enhance re-growth of severed axons. Our results suggest that Asporin and CD109 influence neurites at the lesion site, rather than promoting axon regeneration, to restore neural function in neonates after SCI.

sFlt-1 impairs neurite growth and neuronal differentiation in SH-SY5Y cells and human neurons.

Pre-eclampsia (PE) is a hypertensive disorder of pregnancy which is associated with increased risk of neurodevelopmental disorders in exposed offspring. The pathophysiological mechanisms mediating this relationship are currently unknown, and one potential candidate is the anti-angiogenic factor soluble Fms-like tyrosine kinase 1 (sFlt-1), which is highly elevated in PE. While sFlt-1 can impair angiogenesis via inhibition of VEGFA signalling, it is unclear whether it can directly affect neuronal development independently of its effects on the vasculature. To test this hypothesis, the current study differentiated the human neural progenitor cell (NPC) line ReNcell® VM into a mixed culture of mature neurons and glia, and exposed them to sFlt-1 during development. Outcomes measured were neurite growth, cytotoxicity, mRNA expression of nestin, MBP, GFAP, and ßIII-tubulin, and neurosphere differentiation. sFlt-1 induced a significant reduction in neurite growth and this effect was timing- and dose-dependent up to 100 ng/ml, with no effect on cytotoxicity. sFlt-1 (100 ng/ml) also reduced ßIII-tubulin mRNA and neuronal differentiation of neurospheres. Undifferentiated NPCs and mature neurons/glia expressed VEGFA and VEGFR-2, required for endogenous autocrine and paracrine VEGFA signalling, while sFlt-1 treatment prevented the neurogenic effects of exogenous VEGFA. Overall, these data provide the first experimental evidence for a direct effect of sFlt-1 on neurite growth and neuronal differentiation in human neurons through inhibition of VEGFA signalling, clarifying our understanding of the potential role of sFlt-1 as a mechanism by which PE can affect neuronal development.

Neuritogenic glycosaminoglycan hydrogels promote functional recovery after severe traumatic brain injury.

Objective.Severe traumatic brain injury (sTBI) induced neuronal loss and brain atrophy contribute significantly to long-term disabilities. Brain extracellular matrix (ECM) associated chondroitin sulfate (CS) glycosaminoglycans promote neural stem cell (NSC) maintenance, and CS hydrogel implants have demonstrated the ability to enhance neuroprotection, in preclinical sTBI studies. However, the ability of neuritogenic chimeric peptide (CP) functionalized CS hydrogels in promoting functional recovery, after controlled cortical impact (CCI) and suction ablation (SA) induced sTBI, has not been previously demonstrated. We hypothesized that neuritogenic (CS)CP hydrogels will promote neuritogenesis of human NSCs, and accelerate brain tissue repair and functional recovery in sTBI rats.Approach.We synthesized chondroitin 4-Osulfate (CS-A)CP, and 4,6-O-sulfate (CS-E)CP hydrogels, using strain promoted azide-alkyne cycloaddition (SPAAC), to promote cell adhesion and neuritogenesis of human NSCs,in vitro; and assessed the ability of (CS-A)CP hydrogels in promoting tissue and functional repair, in a novel CCI-SA sTBI model,in vivo. Main results.Results indicated that (CS-E)CP hydrogels significantly enhanced human NSC aggregation and migration via focal adhesion kinase complexes, when compared to NSCs in (CS-A)CP hydrogels,in vitro. In contrast, NSCs encapsulated in (CS-A)CP hydrogels differentiated into neurons bearing longer neurites and showed greater spontaneous activity, when compared to those in (CS-E)CP hydrogels. The intracavitary implantation of (CS-A)CP hydrogels, acutely after CCI-SA-sTBI, prevented neuronal and axonal loss, as determined by immunohistochemical analyses. (CS-A)CP hydrogel implanted animals also demonstrated the significantly accelerated recovery of 'reach-to-grasp' function when compared to sTBI controls, over a period of 5-weeks.Significance.These findings demonstrate the neuritogenic and neuroprotective attributes of (CS)CP 'click' hydrogels, and open new avenues for the development of multifunctional glycomaterials that are functionalized with biorthogonal handles for sTBI repair.

Promotion of neurite outgrowth by 3,5,7,3',4'-pentamethoxyflavone is mediated through ERK signaling pathway in Neuro2a cells.

In this study, the effects of 3,5,7,3',4'-pentamethoxyflavone (KP1), a major bioactive ingredient isolated from the Kaempferia parviflora rhizomes, on a neurite outgrowth in Neuro2a cells and its mechanism have been investigated. KP1 increased concentration-dependently the percentage of neurite-bearing cells. KP1 showed a remarkable capability to elicit neurite outgrowth in Neuro2a cells, as evidenced by morphological alterations and immunostaining using anti-class III ß-tubulin and anti-NeuN antibodies. KP1 also displayed a higher neurogenic activity than retinoic acid (RA), a promoter of neurite outgrowth in Neuro2a cells. KP1 treatment caused significant elevation in phosphorylation of extracellular signal-regulated kinase (ERK), p38 mitogen-activated protein kinase (p38 MAPK) and glycogen synthase kinase-3ß (GSK-3ß). However, KP1-triggered neurite outgrowth was markedly inhibited by treatment with the ERK inhibitor U0126, whereas p38 MAPK inhibitor SB203580 and GSK-3ß inhibitor SB216763 did not influence KP1-induced neurite outgrowth. These results demonstrate that KP1 elicits neurite outgrowth and triggers cell differentiation of Neuro2a cells through ERK signal pathway.

Circulating miR-30e-3p induces disruption of neurite development in SH-SY5Y cells by targeting ABI1, a novel biomarker for schizophrenia.

Schizophrenia (SCZ) represents a set of enduring mental illnesses whose underlying etiology remains elusive, posing a significant challenge to public health. Previous studies have shown that the neurodevelopmental process involving small molecules such as miRNA and mRNA is one of the etiological hypotheses of SCZ. We identified and verified that miR-30e-3p and ABI1 can be used as biomarkers in peripheral blood transcriptome sequencing data of patients with SCZ, and confirmed the regulatory relationship between them. To further explore their involvement, we employed retinoic acid (RA)-treated SH-SY5Y differentiated cells as a model system. Our findings indicate that in RA-induced SH-SY5Y cells, ABI1 expression is up-regulated, while miR-30e-3p expression is down-regulated. Functionally, both miR-30e-3p down-regulation and ABI1 up-regulation promote apoptosis and inhibit the proliferation of SH-SY5Y cells. Subsequently, the immunofluorescence assay detected the expression location and abundance of the neuron-specific protein ß-tubulinIII. The expression levels of neuronal marker genes MAPT, TUBB3 and SYP were detected by RT-qPCR. We observed that these changes of miR-30e-3p and ABI1 inhibit the neurite growth of SH-SY5Y cells. Rescue experiments further support that ABI1 silencing can correct miR-30e-3p down-regulation-induced SH-SY5Y neurodevelopmental defects. Collectively, our results establish that miR-30e-3p's regulation of neurite development in SH-SY5Y cells is mediated through ABI1, highlighting a potential mechanism in SCZ pathogenesis.

Nicotinamide Adenine Dinucleotide Precursor Supplementation Modulates Neurite Complexity and Survival in Motor Neurons from Amyotrophic Lateral Sclerosis Models.

Aims: Increasing nicotinamide adenine dinucleotide (NAD+) availability has been proposed as a therapeutic approach to prevent neurodegeneration in amyotrophic lateral sclerosis (ALS). Accordingly, NAD+ precursor supplementation appears to exert neuroprotective effects in ALS patients and mouse models. The mechanisms mediating neuroprotection remain uncertain but could involve changes in multiple cell types. We investigated a potential direct effect of the NAD+ precursor nicotinamide mononucleotide (NMN) on the health of cultured induced pluripotent stem cell (iPSC)-derived human motor neurons and in motor neurons isolated from two ALS mouse models, that is, mice overexpressing wild-type transactive response DNA binding protein-43 (TDP-43) or the ALS-linked human superoxide dismutase 1 with the G93A mutation (hSOD1G93A). Results: NMN treatment increased the complexity of neuronal processes in motor neurons isolated from both mouse models and in iPSC-derived human motor neurons. In addition, NMN prevented neuronal death induced by trophic factor deprivation. In mouse and human motor neurons expressing ALS-linked mutant superoxide dismutase 1, NMN induced an increase in glutathione levels, but this effect was not observed in nontransgenic or TDP-43 overexpressing motor neurons. In contrast, NMN treatment normalized the TDP-43 cytoplasmic mislocalization induced by its overexpression. Innovation: NMN can directly act on motor neurons to increase the growth and complexity of neuronal processes and prevent the death induced by trophic factor deprivation. Conclusion: Our results support a direct beneficial effect of NAD+ precursor supplementation on the maintenance of the neuritic arbor in motor neurons. Importantly, this was observed in motor neurons isolated from two different ALS models, with and without involvement of TDP-43 pathology, supporting its therapeutic potential in sporadic and familial ALS. Antioxid. Redox Signal. 41, 573-589.

Choline supplementation mitigates effects of bilirubin in cerebellar granule neurons in vitro.

BACKGROUND: Premature infants may suffer from high levels of bilirubin that could lead to neurotoxicity. Bilirubin has been shown to decrease L1-mediated ERK1/2 signaling, L1 phosphorylation, and L1 tyrosine 1176 dephosphorylation. Furthermore, bilirubin redistributes L1 into lipid rafts (LR) and decreases L1-mediated neurite outgrowth. We demonstrate that choline supplementation improves L1 function and signaling in the presence of bilirubin. METHODS: Cerebellar granule neurons (CGN) were cultured with and without supplemental choline, and the effects on L1 signaling and function were measured in the presence of bilirubin. L1 activation of ERK1/2, L1 phosphorylation and dephosphorylation were measured. L1 distribution in LR was quantified and neurite outgrowth of CGN was determined. RESULTS: Forty µM choline significantly reduced the effect of bilirubin on L1 activation of ERK1/2 by 220% (p = 0.04), and increased L1 triggered changes in tyrosine phosphorylation /dephosphorylation of L1 by 34% (p = 0.026) and 35% (p = 0.02) respectively. Choline ameliorated the redistribution of L1 in lipid rafts by 38% (p = 0.02) and increased L1-mediated mean neurite length by 11% (p = 0.04). CONCLUSION: Choline pretreatment of CGN significantly reduced the disruption of L1 function by bilirubin. The supplementation of pregnant women and preterm infants with choline may increase infant resilience to the effects of bilirubin. IMPACT: This article establishes choline as an intervention for the neurotoxic effects of bilirubin on lipid rafts. This article provides clear evidence toward establishing one intervention for bilirubin neurotoxicity, where little is understood. This article paves the way for future investigation into the mechanism of the ameliorative effect of choline on bilirubin neurotoxicity.

A small-molecule PI3Kα activator for cardioprotection and neuroregeneration.

Harnessing the potential beneficial effects of kinase signalling through the generation of direct kinase activators remains an underexplored area of drug development1-5. This also applies to the PI3K signalling pathway, which has been extensively targeted by inhibitors for conditions with PI3K overactivation, such as cancer and immune dysregulation. Here we report the discovery of UCL-TRO-1938 (referred to as 1938 hereon), a small-molecule activator of the PI3Kα isoform, a crucial effector of growth factor signalling. 1938 allosterically activates PI3Kα through a distinct mechanism by enhancing multiple steps of the PI3Kα catalytic cycle and causes both local and global conformational changes in the PI3Kα structure. This compound is selective for PI3Kα over other PI3K isoforms and multiple protein and lipid kinases. It transiently activates PI3K signalling in all rodent and human cells tested, resulting in cellular responses such as proliferation and neurite outgrowth. In rodent models, acute treatment with 1938 provides cardioprotection from ischaemia-reperfusion injury and, after local administration, enhances nerve regeneration following nerve crush. This study identifies a chemical tool to directly probe the PI3Kα signalling pathway and a new approach to modulate PI3K activity, widening the therapeutic potential of targeting these enzymes through short-term activation for tissue protection and regeneration. Our findings illustrate the potential of activating kinases for therapeutic benefit, a currently largely untapped area of drug development.