Wnt/β-catenin signaling promotes neurogenesis in the diencephalospinal dopaminergic system of embryonic zebrafish

Examining structure-activity relationships of ManNAc analogs used in the metabolic glycoengineering of human neural stem cells

This study defines biochemical mechanisms that contribute to novel neural-regenerative activities we recently demonstrated for thiol-modified ManNAc analogs in human neural stem cells (hNSCs) by comparing our lead drug candidate for brain repair, "TProp," to a "size-matched" N-alkyl control analog, "But." These analogs biosynthetically install non-natural sialic acids into cell surface glycans, altering cell surface receptor activity and adhesive properties of cells. In this study, TProp modulated sialic acid-related biology in hNSCs to promote neuronal differentiation through modulation of cell adhesion molecules (integrins α6, β1, E-cadherin, and PSGL-1) and stem cell markers. By comparison, But elicited minimal change to these endpoints, indicating dependence on the chemical properties of the thiol group of non-natural sialic acids and not the size of this sugar's N-acyl group. Conversely, But elicited distinct intracellular responses including increased nestin expression (~6-fold) and the modulation of several metabolites identified through cell-wide screening. Metabolites up-regulated by But included dopamine and norfenenfrine, suggesting that this analog may be a drug candidate for treating neural damage associated with conditions such as Parkinson's disease. The metabolomics data also provided new insights into the neuroprotective effects of TProp when used to treat brain injury by upregulation of anti-inflammatory metabolites (e.g., α- & γ-linolenic acids) valuable for dampening injury- and treatment-related inflammation. Finally, these analogs modulate compounds that control proline (e.g., 1-pyrroline-2-carboxylate), a master regulator of many cellular activities. Overall, this study presents new mechanisms and pathways to exploit metabolic glycoengineering for neural repair and treatment of neurodegenerative diseases.

In vitro β-catenin attenuation by a mefloquine-loaded core-shell nano emulsion strategy to suppress liver cancer cells

Liver cancer, with its robust metastatic propensity, imposes a substantial global health burden of around 800 000 new cases annually. Mutations in the Wnt/β-catenin pathway genes are common in liver cancer, driving over 80% of cases. Targeting this pathway could potentially lead to better treatments. The aim of the present study was to develop a novel strategy for targeting the Wnt/β-catenin pathway while blocking the growth and division, of liver cancer cells and downregulating gene expression. This was achieved by formulating a repurposed drug (mefloquine)-loaded garlic nano-emulsion (GNE) with gold nanoparticles (GNPs) as a core-shell nano-emulsion (MQ/GNE-GNP). The biocompatible core-shell nano-emulsion (MQ/GNE-GNP) exhibited a size distribution in the range of 50-100 nm, high stability, excellent hydrophilicity, good biosafety, and sustained release. Human liver cancer cells were exposed to MQ/GNE, GNPs, and MQ/GNE-GNP at varying concentrations, and the effects were assessed through analysis of the cytotoxicity, reactive oxygen species, cell death, cell cycle analysis, and gene expression studies. It was found that MQ/GNE-GNP arrested HepG2 cells in the sub G0/G1phase and induced apoptosis. The anticancer efficacy of the core-shell nano-emulsion (MQ/GNE-GNP) resulted in higher cell death in the AO/PI staining studies, demonstrating its greater anticancer efficacy. The administration of MQ/GNE-GNP downregulated the overall expression of nuclear β-catenin, thereby suppressing the Wnt/β-catenin pathway. The protein expression level of Wnt 1 was upregulated, while β-catenin expression was significantly decreased. The core-shell nano-emulsion, incorporating a repurposed drug, could disrupt the β-catenin connections in the Wnt/β-catenin pathway. In conclusion, MQ/GNE-GNP could be a promising core-shell nano emulsion for the effective treatment of liver cancer by targeting the Wnt/β-catenin pathway.

Wnt/β-catenin Signaling in Central Nervous System Regeneration

The Wnt/β-catenin signaling pathway plays a pivotal role in the development, maintenance, and repair of the central nervous system (CNS). This chapter explores the diverse functions of Wnt/β-catenin signaling, from its critical involvement in embryonic CNS development to its reparative and plasticity-inducing roles in response to CNS injury. We discuss how Wnt/β-catenin signaling influences various CNS cell types-astrocytes, microglia, neurons, and oligodendrocytes-each contributing to repair and plasticity after injury. The chapter also addresses the pathway's involvement in CNS disorders such as Alzheimer's and Parkinson's diseases, psychiatric disorders, and traumatic brain injury (TBI), highlighting potential Wnt-based therapeutic approaches. Lastly, zebrafish are presented as a promising model organism for studying CNS regeneration and neurodegenerative diseases, offering insights into future research and therapeutic development.

Curcumin triggers the Wnt/β-catenin pathway and shields neurons from injury caused by intermittent hypoxia

The objective of this study was to explore the molecular basis through which Curcumin (Cur) mitigates neuronal damage caused by obstructive sleep apnea (OSA). HT22 was used to simulate intermittent hypoxia (IH) injury and explore the effect of Cur on these cells. We evaluated the cell viability, cytotoxicity, apoptosis, proliferation, and Wnt/β-catenin (WβC) pathway. IWR-1 was used to block the pathway and investigate the protective mechanism of Cur. We constructed an in vivo model of IH to validate the results of the cellular experiments. IH accelerated apoptosis and cytotoxicity, suppressed proliferation, and decreased the activity of the WβC pathway. Cur can significantly improve cell viability, reduce apoptosis rate and cell toxicity, promote cell proliferation, and up-regulate the WβC. After blocking the WβC pathway, the proliferative effect of Cur was observably weakened. In vivo, IH caused hippocampal damage and inhibited WβC pathway activity in mice, which was ameliorated by Cur treatment. This implies that Cur could be a novel treatment option for neurological impairment brought on by OSA.

Multi-Omics Approach Reveals Genes and Pathways Affected in Miller-Dieker Syndrome

Miller-Dieker syndrome (MDS) is a rare neurogenetic disorder resulting from a heterozygous deletion of 26 genes in the MDS locus on human chromosome 17. MDS patients often die in utero and only 10% of those who are born reach 10 years of age. Current treatments mostly prevent complications and control seizures. A detailed understanding of the pathogenesis of MDS through gene expression studies would be useful in developing precise medical approaches toward MDS. To better understand MDS at the molecular level, we performed RNA sequencing on RNA and mass spectrometry on total protein isolated from BJ (non-MDS) cells and GM06097 (MDS) cells, which were derived from a healthy individual and an MDS patient, respectively. Differentially expressed genes (DEGs) at the RNA and protein levels involved genes associated with phenotypic features reported in MDS patients (CACNG4, ADD2, SPTAN1, SHANK2), signaling pathways (GABBR2, CAMK2B, TRAM-1), and nervous system development (CAMK2B, BEX1, ARSA). Functional assays validated enhanced calcium signaling, downregulated protein translation, and cell migration defects in MDS. Interestingly, overexpression of methyltransferase-like protein 16 (METTL16), a protein encoded in the MDS locus, restored defects in protein translation, phosphor states of mTOR (mammalian target of rapamycin) pathway regulators, and cell migration in MDS cells. Although DNA- and RNA-modifying enzymes were among the DEGs and the intracellular SAM/SAH ratio was eightfold lower in MDS cells, global nucleoside modifications remained unchanged. Thus, this study identified specific genes and pathways responsible for the gene expression changes, which could lead to better therapeutics for MDS patients.

Unleashing the Power of Induced Pluripotent stem Cells in in vitro Modelling of Lesch-Nyhan Disease

Lesch-Nyhan disease (LND) is a monogenic rare neurodevelopmental disorder caused by a deficiency in hypoxanthine-guanine phosphoribosyltransferase (HPRT), the key enzyme of the purines salvage pathway. Beyond its well-documented metabolic consequences, HPRT deficiency leads to a distinctive neurobehavioral syndrome characterized by motor disabilities, cognitive deficits, and self-injurious behavior. Although various cell and animal models have been developed to investigate LND pathology, none have adequately elucidated the underlying mechanisms of its neurological alterations. Recent advances in human pluripotent stem cell research and in vitro differentiation techniques have ushered in a new era in rare neurodevelopmental disorders research. Pluripotent stem cells, with their ability to propagate indefinitely and to differentiate into virtually any cell type, offer a valuable alternative for modeling rare diseases, allowing for the detection of pathological events from the earliest stages of neuronal network development. Furthermore, the generation of patient-derived induced pluripotent stem cells using reprogramming technology provides an opportunity to develop a disease-relevant model within the context of a patient-specific genome. In this review, we examine current stem cell-based models of LND and assess their potential as optimal models for exploring key pathological molecular events during neurogenesis and for the discovering novel treatment options. We also address the limitations, challenges, and future prospects for improving the use of iPSCs in LND research.

Effect of High Glucose on Embryological Development of Zebrafish, Brachyodanio, Rerio through Wnt Pathway

Gestational diabetes mellitus (GDM) is a worldwide pregnancy complication. Gestational diabetes can significantly impact fetus development. However, the effects of high glucose on embryological development post-fertilization are yet to be researched. Danio rerio embryos are a great model for studying embryonic development. In this study, the effects on embryological (morphological and genetic) development were examined in the presence of a high-glucose environment that mimics the developing fetus in pregnant women with GDM. Fertilized zebrafish embryos were treated with normal media and high glucose for 5 days from 3 h post-fertilization (hpf) to 96 hpf, respectively, as control and experimental groups. Morphological changes are recorded with microscope images. Hatch rate and heart rate are compared between groups at set time points. RNA-Seq is performed to examine the gene changes in the experimental group. Glucose delayed the zebrafish embryo development by slowing the hatch rate by about 24 h. The brain, heart, and tail started showing smaller morphology in the glucose group compared to the control group at 24 hpf. Heart rate was faster in the glucose group compared to the control group on days 2 and 3 with a statistically significant difference. Among the zebrafish whole genome, the significantly changed genes were 556 upregulated genes and 1118 downregulated genes, respectively, in the high-glucose group. The metabolic and Wnt pathways are altered under high-glucose conditions. These conditions contribute to significant physiological differences that may provide insight into the functionality of post-embryological development.

Targeting WNT signalling pathways as new therapeutic strategies for osteoarthritis

Osteoarthritis (OA) is a highly prevalent chronic joint disease and the leading cause of disability. Currently, no drugs are available to control joint damage or ease the associated pain. The wingless-type (WNT) signalling pathway is vital in OA progression. Excessive activation of the WNT signalling pathway is pertinent to OA progression and severity. Therefore, agonists and antagonists of the WNT pathway are considered potential drug candidates for OA treatment. For example, SM04690, a novel small molecule inhibitor of WNT signalling, has demonstrated its potential in a recent phase III clinical trial as a disease-modifying osteoarthritis drug (DMOAD). Therefore, targeting the WNT signalling pathway may be a distinctive approach to developing particular agents helpful in treating OA. This review aims to update the most recent progress in OA drug development by targeting the WNT pathway. In this, we introduce WNT pathways and their crosstalk with other signalling pathways in OA development and highlight the role of the WNT signalling pathway as a key regulator in OA development. Several articles have reviewed the Wnt pathway from different aspects. This candid review provides an introduction to WNT pathways and their crosstalk with other signalling pathways in OA development, highlighting the role of the WNT signalling pathway as a key regulator in OA development with the latest research. Particularly, we emphasise the state-of-the-art in targeting the WNT pathway as a promising therapeutic approach for OA and challenges in their development and the nanocarrier-based delivery of WNT modulators for treating OA.

Eleven Crucial Pesticides Appear to Regulate Key Genes That Link MPTP Mechanism to Cause Parkinson's Disease through the Selective Degeneration of Dopamine Neurons

Pesticides kill neurons, but the mechanism leading to selective dopaminergic loss in Parkinson's disease (PD) is unknown. Understanding the pesticide's effect on dopaminergic neurons (DA) can help to screen and treat PD. The critical uptake of pesticides by the membrane receptors at DA is hypothesized to activate a signaling cascade and accelerate degeneration. Using MPTP as a reference, we demonstrate the mechanisms of eleven crucial pesticides through molecular docking, protein networks, regulatory pathways, and prioritization of key pesticide-regulating proteins. Participants were recruited and grouped into control and PD based on clinical characteristics as well as pesticide traces in their blood plasma. Then, qPCR was used to measure pesticide-associated gene expression in peripheral blood mononuclear cells between groups. As a result of molecular docking, all eleven pesticides and the MPTP showed high binding efficiency against 274 membrane receptor proteins of DA. Further, the protein interaction networks showed activation of multiple signaling cascades through these receptors. Subsequent analysis revealed 31 biological pathways shared by all 11pesticides and MPTP that were overrepresented by 46 crucial proteins. Among these, CTNNB1, NDUFS6, and CAV1 were prioritized to show a significant change in gene expression in pesticide-exposed PD which guides toward therapy.

Regulatory role of apelin receptor signaling in migration and differentiation of mouse embryonic stem cell-derived mesoderm cells and mesenchymal stem/stromal cells

Mesoderm-derived cells, including bone, muscle, and mesenchymal stem/stromal cells (MSCs), constitute various parts of vertebrate body. Cell therapy with mesoderm specification in vitro may be a promising treatment for diseases affecting organs of mesodermal origin. Repair and regeneration of damaged organs with in vitro generation of mesoderm-derived tissues and MSCs hold a great potential for regenerative therapy. Therefore, understanding the signaling pathways involving mesoderm and mesoderm-derived cellular differentiation is important. Previous findings indicated the importance of Apelin receptor (Aplnr) signaling, during embryonic development, in gastrulation, cell migration, and differentiation. Nevertheless, regulatory role of Aplnr pathway in differentiation of mesoderm and mesoderm-derived MSCs remains unclear. In the current study, we tried to elucidate the role of Aplnr signaling during mesoderm cell migration and differentiation from mouse embryonic stem cells (mESCs). By activating and suppressing Aplnr signaling pathway via peptide, small molecule, and genetic modifications including siRNA- and shRNA-mediated knockdown and CRISPR-Cas9-mediated knockout (KO), we revealed that Aplnr signaling not only induces migration of cells during germ layer formation but also enhances mesoderm differentiation through FGF/MAPK pathway. Antibody array and LC/MS protein profiling data demonstrated that Apelin-13 treatment enhanced cell cycle, EGFR, FGF, Wnt, and Integrin signaling pathway proteins. Furthermore, Aplelin-13 treatment improved MSC characteristics, with mesenchymal phenotype and high expression of MSC markers, and silencing Aplnr signaling components resulted in significantly reduced expression of MSC markers. Also, Aplnr signaling activity enhanced proliferation and survival of the cells during MSC derivation from mesoderm.

Behavioral changes and transcriptomic effects at embryonic and post-embryonic stages reveal the toxic effects of 2,2',4,4'-tetrabromodiphenyl ether on neurodevelopment in zebrafish (Danio rerio)

Polybrominated biphenyl ethers (PBDEs) are new persistent pollutants that are widely exist in the environment and have many toxic effects. However, their toxicity mechanisms on neurodevelopment are still unclear. In this study, zebrafish embryos were exposed to 2, 2', 4, 4'-tetrabromodiphenyl ether (BDE-47) (control, 10, 50 and 100 μg/L) at 2 h postfertilization (hpf) - 7 dpf. Locomotion analysis indicated that BDE-47 increased spontaneous coiling activity in zebrafish embryos under high-intensity light stimuli and decreased locomotor in zebrafish larvae. RNA-Seq analysis revealed that most of the up-regulated pathways were related to the metabolism of cells and tissues, while the down-regulated pathways were related to neurodevelopment. Consistent with the locomotion and KEGG results, BDE-47 affected the expression of genes for central nervous system (gfap, mbpa, bdnf & pomcb), early neurogenesis (neurog1 & elavl3), and axonal development (tuba1a, tuba1b, tuba1c, syn2a, gap43 & shha). Furthermore, BDE-47 interfered with gene expression of the Wnt signaling pathway, especially during embryonic stages, suggesting that the mechanisms of BDE-47 toxicity to zebrafish at various stages of neurodevelopment may be different. In summary, early neurodevelopment effects and metabolic disturbances may have contributed to the abnormal neurobehavioral changes induced by BDE-47 in zebrafish embryos/larvae, suggesting the neurodevelopmental toxicity of BDE-47.

Modeling Movement Disorders via Generation of hiPSC-Derived Motor Neurons

Generation of motor neurons (MNs) from human-induced pluripotent stem cells (hiPSCs) overcomes the limited access to human brain tissues and provides an unprecedent approach for modeling MN-related diseases. In this review, we discuss the recent progression in understanding the regulatory mechanisms of MN differentiation and their applications in the generation of MNs from hiPSCs, with a particular focus on two approaches: induction by small molecules and induction by lentiviral delivery of transcription factors. At each induction stage, different culture media and supplements, typical growth conditions and cellular morphology, and specific markers for validation of cell identity and quality control are specifically discussed. Both approaches can generate functional MNs. Currently, the major challenges in modeling neurological diseases using iPSC-derived neurons are: obtaining neurons with high purity and yield; long-term neuron culture to reach full maturation; and how to culture neurons more physiologically to maximize relevance to in vivo conditions.

Hypoplasia of dopaminergic neurons by hypoxia-induced neurotoxicity is associated with disrupted swimming development of larval zebrafish

Hypoxic injury to the developing brain increases the risk of permanent behavioral deficits, but the precise mechanisms of hypoxic injury to the developing nervous system are poorly understood. In this study, we characterized the effects of developmental hypoxia (1% pO₂ from 24 to 48 h post-fertilization, hpf) on diencephalic dopaminergic (DA) neurons in larval zebrafish and the consequences on the development of swimming behavior. Hypoxia reduced the number of diencephalic DA neurons at 48 hpf. Returning zebrafish larvae to normoxia after the hypoxia (i.e., hypoxia-recovery, HR) induced reactive oxygen species (ROS) accumulation. Real-time qPCR results showed that HR caused upregulation of proapoptotic genes, including p53 and caspase3, suggesting the potential for ROS-induced cell death. With HR, we also found an increase in TUNEL-positive DA neurons, a persistent reduction in the number of diencephalic DA neurons, and disrupted swimming development and behavior. Interestingly, post-hypoxia (HR) with the antioxidant N-acetylcysteine partially restored the number of DA neurons and spontaneous swimming behavior, demonstrating potential recovery from hypoxic injury. The present study provides new insights for understanding the mechanisms responsible for motor disability due to developmental hypoxic injury.

Probiotics Enhance Bone Growth and Rescue BMP Inhibition: New Transgenic Zebrafish Lines to Study Bone Health

Zebrafish larvae, especially gene-specific mutants and transgenic lines, are increasingly used to study vertebrate skeletal development and human pathologies such as osteoporosis, osteopetrosis and osteoarthritis. Probiotics have been recognized in recent years as a prophylactic treatment for various bone health issues in humans. Here, we present two new zebrafish transgenic lines containing the coding sequences for fluorescent proteins inserted into the endogenous genes for sp7 and col10a1a with larvae displaying fluorescence in developing osteoblasts and the bone extracellular matrix (mineralized or non-mineralized), respectively. Furthermore, we use these transgenic lines to show that exposure to two different probiotics, Bacillus subtilis and Lactococcus lactis, leads to an increase in osteoblast formation and bone matrix growth and mineralization. Gene expression analysis revealed the effect of the probiotics, particularly Bacillus subtilis, in modulating several skeletal development genes, such as runx2, sp7, spp1 and col10a1a, further supporting their ability to improve bone health. Bacillus subtilis was the more potent probiotic able to significantly reverse the inhibition of bone matrix formation when larvae were exposed to a BMP inhibitor (LDN212854).