p53 controls genomic stability and temporal differentiation of human neural stem cells and affects neural organization in human brain organoids

Ionizing radiation inhibits zebrafish embryo hatching through induction of tissue inhibitors of metalloproteinases (TIMPs) expression

Ionizing radiation (IR) has garnered growing attention because of its biological effects on aquatic organisms and humans. Here, we identify the most impacted organs and uncover the molecular mechanisms causing the changes in the context of vertebrate development using single-cell RNA sequencing. Alterations in cellular composition and biological functions were explored using transcriptomic profiling of zebrafish embryos exposed to 5 Gy. Single-cell RNA sequencing analyses unveiled notable shifts in the proportions of brain/central nervous system and hatching gland clusters. Although IR exposure led to increased expression of hatching enzymes, a significant but mild delay in hatching was observed following 5 Gy IR exposure. Gene Ontology analysis showed an increased expression of tissue inhibitors of metalloproteinases (TIMPs), known as matrix metalloproteinase inhibitors, which was confirmed via whole-mount in situ hybridization. Correlation analysis linked TIMPs to transcription factors cebpb and cebpd, which were significantly correlated post-IR exposure. Although no morphological changes were observed in some organs, including the brain, the study reveals substantial alterations in developing vertebrates. Notably, despite increased hatching enzymes, elevated TIMPs in the hatching gland suggest a regulatory mechanism impacting hatching activity. This research contributes to comprehending the ecological repercussions of IR exposure, emphasizing the importance of safety measures for aquatic ecosystems and overall environmental health.

Mouse cortical organoids reveal key functions of p73 isoforms: TAp73 governs the establishment of the archetypical ventricular-like zones while DNp73 is central in the regulation of neural cell fate

Introduction

Neurogenesis is tightly regulated in space and time, ensuring the correct development and organization of the central nervous system. Critical regulators of brain development and morphogenesis in mice include two members of the p53 family: p53 and p73. However, dissecting the in vivo functions of these factors and their various isoforms in brain development is challenging due to their pleiotropic effects. Understanding their role, particularly in neurogenesis and brain morphogenesis, requires innovative experimental approaches.

Methods

To address these challenges, we developed an efficient and highly reproducible protocol to generate mouse brain organoids from pluripotent stem cells. These organoids contain neural progenitors and neurons that self-organize into rosette-like structures resembling the ventricular zone of the embryonic forebrain. Using this model, we generated organoids from p73-deficient mouse cells to investigate the roles of p73 and its isoforms (TA and DNp73) during brain development.

Results and Discussion

Organoids derived from p73-deficient cells exhibited increased neuronal apoptosis and reduced neural progenitor proliferation, linked to compensatory activation of p53. This closely mirrors previous in vivo observations, confirming that p73 plays a pivotal role in brain development. Further dissection of p73 isoforms function revealed a dual role of p73 in regulating brain morphogenesis, whereby TAp73 controls transcriptional programs essential for the establishment of the neurogenic niche structure, while DNp73 is responsible for the precise and timely regulation of neural cell fate. These findings highlight the distinct roles of p73 isoforms in maintaining the balance of neural progenitor cell biology, providing a new understanding of how p73 regulates brain morphogenesis.

Molecular pathology, developmental changes and synaptic dysfunction in (pre-) symptomatic human C9ORF72-ALS/FTD cerebral organoids

A hexanucleotide repeat expansion (HRE) in C9ORF72 is the most common genetic cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Human brain imaging and experimental studies indicate early changes in brain structure and connectivity in C9-ALS/FTD, even before symptom onset. Because these early disease phenotypes remain incompletely understood, we generated iPSC-derived cerebral organoid models from C9-ALS/FTD patients, presymptomatic C9ORF72-HRE (C9-HRE) carriers, and controls. Our work revealed the presence of all three C9-HRE-related molecular pathologies and developmental stage-dependent size phenotypes in cerebral organoids from C9-ALS/FTD patients. In addition, single-cell RNA sequencing identified changes in cell type abundance and distribution in C9-ALS/FTD organoids, including a reduction in the number of deep layer cortical neurons and the distribution of neural progenitors. Further, molecular and cellular analyses and patch-clamp electrophysiology detected various changes in synapse structure and function. Intriguingly, organoids from all presymptomatic C9-HRE carriers displayed C9-HRE molecular pathology, whereas the extent to which more downstream cellular defects, as found in C9-ALS/FTD models, were detected varied for the different presymptomatic C9-HRE cases. Together, these results unveil early changes in 3D human brain tissue organization and synaptic connectivity in C9-ALS/FTD that likely constitute initial pathologies crucial for understanding disease onset and the design of therapeutic strategies.

Neural Correlates of Early-Life Urbanization and Their Spatial Relationships with Gene Expression, Neurotransmitter, and Behavioral Domain Atlases

Previous neuroimaging research has established associations between urban exposure during early life and alterations in brain function and structure. However, the molecular mechanisms and behavioral relevance of these associations remain largely unknown. Here, we aimed to address this question using a combined analysis of multimodal data. Initially, we calculated amplitude of low-frequency fluctuations (ALFF) and gray matter volume (GMV) using resting-state functional and structural MRI to investigate their associations with early-life urbanization in a large sample of 511 healthy young adults. Then, we examined the spatial relationships of the identified neural correlates of early-life urbanization with gene expression, neurotransmitter, and behavioral domain atlases. Results showed that higher early-life urbanization scores were correlated with increased ALFF of the right fusiform gyrus and decreased GMV of the left dorsal medial prefrontal cortex and left precuneus. Remarkably, the identified neural correlates of early-life urbanization were spatially correlated with expression of gene categories primarily involving immune system process, signal transduction, and cellular metabolic process. Concurrently, there were significant associations between the neural correlates and specific neurotransmitter systems including dopamine, acetylcholine, and serotonin. Finally, we found that the ALFF correlates were associated with behavioral terms including "perception," "sensory," "cognitive control," and "reasoning." Apart from expanding existing knowledge of early-life urban environmental risk for mental disorders and health in general, our findings may contribute to an emerging framework for integrating social science, neuroscience, genetics, and public policy to respond to the major health challenge of world urbanization.

P53 independent pathogenic mechanisms contribute to BubR1 microcephaly

The mosaic variegated aneuploidy (MVA)-associated gene Budding Uninhibited by Benzimidazole 1B (BUB1B) encodes BUBR1, a core member of the spindle assembly checkpoint complex that ensures kinetochore-spindle attachment for faithful chromosome segregation. BUB1B mutation in humans and its deletion in mice cause microcephaly. In the absence of BubR1 in mice, massive cell death reduces cortical cells during neurogenesis. However, the molecular and cellular mechanisms triggering cell death are unknown. In this study, we performed three-dimensional imaging analysis of mitotic BubR1-deficient neural progenitors in a murine model to show profound chromosomal segregation defects and structural abnormalities. Chromosomal defects and accompanying DNA damage result in P53 activation and apoptotic cell death in BubR1 mutants. To test whether the P53 cell death pathway is responsible for cortical cell loss, we co-deleted Trp53 in BubR1-deficient cortices. Remarkably, we discovered that residual apoptotic cell death remains in double mutants lacking P53, suggesting P53-independent apoptosis. Furthermore, the minimal rescue of cortical size and cortical neuron numbers in double mutant mice suggests the compelling extent of alternative death mechanisms in the absence of P53. This study demonstrates a potential pathogenic mechanism for microcephaly in MVA patients and uncovers the existence of powerful means of eliminating unfit cells even when the P53 death pathway is disabled.

Brain organoids are new tool for drug screening of neurological diseases

At the level of in vitro drug screening, the development of a phenotypic analysis system with high-content screening at the core provides a strong platform to support high-throughput drug screening. There are few systematic reports on brain organoids, as a new three-dimensional in vitro model, in terms of model stability, key phenotypic fingerprint, and drug screening schemes, and particularly regarding the development of screening strategies for massive numbers of traditional Chinese medicine monomers. This paper reviews the development of brain organoids and the advantages of brain organoids over induced neurons or cells in simulated diseases. The paper also highlights the prospects from model stability, induction criteria of brain organoids, and the screening schemes of brain organoids based on the characteristics of brain organoids and the application and development of a high-content screening system.

Generation of a human haploid neural stem cell line for genome-wide genetic screening

BACKGROUND

Haploid embryonic stem cells (haESCs) have been established in many species. Differentiated haploid cell line types in mammals are lacking due to spontaneous diploidization during differentiation that compromises lineage-specific screens.

AIM

To derive human haploid neural stem cells (haNSCs) to carry out lineage-specific screens.

METHODS

Human haNSCs were differentiated from human extended haESCs with the help of Y27632 (ROCK signaling pathway inhibitor) and a series of cytokines to reduce diploidization. Neuronal differentiation of haNSCs was performed to examine their neural differentiation potency. Global gene expression analysis was con-ducted to compare haNSCs with diploid NSCs and haESCs. Fluorescence activated cell sorting was performed to assess the diploidization rate of extended haESCs and haNSCs. Genetic manipulation and screening were utilized to evaluate the significance of human haNSCs as genetic screening tools.

RESULTS

Human haESCs in extended pluripotent culture medium showed more compact and smaller colonies, a higher efficiency in neural differentiation, a higher cell survival ratio and higher stability in haploidy maintenance. These characteristics effectively facilitated the derivation of human haNSCs. These human haNSCs can be generated by differentiation and maintain haploidy and multipotency to neurons and glia in the long term in vitro. After PiggyBac transfection, there were multiple insertion sites in the human haNSCs’ genome, and the insertion sites were evenly spread across all chromosomes. In addition, after the cells were treated with manganese, we were able to generate a list of manganese-induced toxicity genes, demonstrating their utility as genetic screening tools.

CONCLUSION

This is the first report of a generated human haploid somatic cell line with a complete genome, proliferative ability and neural differentiation potential that provides cell resources for recessive inheritance and drug targeted screening.

Activated KRAS reprograms neural progenitor cells to glioma stem cell‑like phenotype

Glioma is the most common primary brain tumor. Glioma stem cells (GSCs) are the origin of gliomagenesis and may develop from normal neural progenitor cells (NPCs). However, how neoplastic transformation occurs in normal NPCs and the role of the Ras/Raf/MAPK pathway in NPC transformation is unclear. The present study generated NPCs from human embryonic stem cells (ESCs) carrying gene alterations in the Ras/Raf/MAPK pathway. The CCK‑8 proliferation, single‑cell clonal expansion, cell migration, RT‑qPCR, immunofluorescence staining, western blotting, transcriptome and Seahorse analyses, and intracranial implantation assay were performed to identify the characterization of transformed NPCs in vitro and in vivo. Brain organoids were used to verify the phenotypes transforming in NPCs. KRAS‑activated NPCs exhibited increased proliferation and migration in vitro. KRAS‑activated NPCs showed atypical morphology and formed aggressive tumors in immunodeficient mice. At the molecular level, KRAS‑activated NPCs displayed neoplasm‑associated metabolic and gene expression profiles. Moreover, activation of KRAS led to substantial cell proliferation and abnormal structure in ESC‑derived brain organoids. The present study showed that activated KRAS transformed normal NPCs to GSC‑like cells and established a simple cellular model to investigate gliomagenesis.

Ethical Implications in Making Use of Human Cerebral Organoids for Investigating Stress-Related Mechanisms and Disorders

The generation of three-dimensional cerebral organoids from human-induced pluripotent stem cells (hPSC) has facilitated the investigation of mechanisms underlying several neuropsychiatric disorders, including stress-related disorders, namely major depressive disorder and post-traumatic stress disorder. Generating hPSC-derived neurons, cerebral organoids, and even assembloids (or multi-organoid complexes) can facilitate research into biomarkers for stress susceptibility or resilience and may even bring about advances in personalized medicine and biomarker research for stress-related psychiatric disorders. Nevertheless, cerebral organoid research does not come without its own set of ethical considerations. With increased complexity and resemblance to in vivo conditions, discussions of increased moral status for these models are ongoing, including questions about sentience, consciousness, moral status, donor protection, and chimeras. There are, however, unique ethical considerations that arise and are worth looking into in the context of research into stress and stress-related disorders using cerebral organoids. This paper provides stress research-specific ethical considerations in the context of cerebral organoid generation and use for research purposes. The use of stress research as a case study here can help inform other practices of in vitro studies using brain models with high ethical considerations.

An entosis-like process induces mitotic disruption in Pals1 microcephaly pathogenesis

Entosis is cell cannibalism utilized by tumor cells to engulf live neighboring cells for pro- or anti-tumorigenic purposes. It is unknown whether this extraordinary cellular event can be pathogenic in other diseases such as microcephaly, a condition characterized by a smaller than normal brain at birth. We find that mice mutant for the human microcephaly-causing gene Pals1, which exhibit diminished cortices due to massive cell death, also exhibit nuclei enveloped by plasma membranes inside of dividing cells. These cell-in-cell (CIC) structures represent a dynamic process accompanied by lengthened mitosis and cytokinesis abnormalities. As shown in tumor cells, ROCK inhibition completely abrogates CIC structures and restores the normal length of mitosis. Moreover, genetic elimination of Trp53 produces a remarkable rescue of cortical size along with substantial reductions of CIC structures and cell death. These results provide a novel pathogenic mechanism by which microcephaly is produced through entotic cell cannibalism.

Generation of human haploid neural stem cells from parthenogenetic embryonic stem cells.. [DOI: 10.21203/rs.3.rs-2332761/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

Recently, haploid embryonic stem cells (haESCs) have been established in many species and widely used in forward and reverse genetic screening. Differentiated haploid cell line types in mammals are lacking due to spontaneous diploidization during differentiation that compromises lineage-specific screens. Human embryonic stem cells are widely used in basic and preclinical research. In this work, we report that human haESCs in extended pluripotent culture medium showed more compact colonies, higher efficiency in neural differentiation, and higher stability in haploidy maintenance, which effectively facilitated the derivation of haNSCs. Human haploid neural stem cells (haNSCs) can be generated by differentiation and maintain haploidy and multipotency to neurons and glia in the long term in vitro. After PiggyBac transfection, there were multiple insertion sites in the haNSC genome and the insertion sites evenly spread across all chromosomes. This is the first human haploid somatic cell line with a complete genome, proliferative ability and neural differentiation potential, which provides cell resources for recessive inheritance and drug targeted screening.

Comprehensive genomic analysis of primary malignant melanoma of the esophagus reveals similar genetic patterns compared with epithelium-associated melanomas

Primary malignant melanoma of the esophagus (PMME) is an exceedingly rare disease with a poor prognosis. The etiology of PMME remains largely unknown and genetic characteristics are yet to be clarified, essential for identifying potential therapeutic targets and defining treatment guidelines. Here, we performed whole-exome sequencing on 47 formalin-fixed paraffin-embedded specimens from 18 patients with PMME, including 23 tumor samples, 6 metastatic lymph nodes, and 18 tumor-adjacent normal tissues. The genomic features of PMME were comprehensively characterized, and comparative genomic analysis was further performed between these specimens and 398 skin cutaneous melanomas (SKCM), 67 non-esophagus mucosal melanomas (NEMM), and 79 uveal melanomas (UVM). In the PMME cohort, recurrently mutated driver genes, such as MUC16, RANBP2, NRAS, TP53, PTPRT, NF1, MUC4, KMT2C, and BRAF, were identified. All RANBP2 mutations were putatively deleterious, and most affected samples had multipoint mutations. Furthermore, RANBP2 showed parallel evolution by multiregional analysis. Whole-genome doubling was an early truncal event that occurred before most driver mutations, except for in TP53. An ultraviolet radiation-related mutational signature, SBS38, was identified as specific to epithelial melanomas and could predict inferior survival outcomes in both PMME and SKCM patients. Comparing the mutational and copy number landscapes between PMME and other subtypes of melanoma revealed that PMME has a similar genomic pattern and biological characteristics to SKCM. In summary, we comprehensively defined the key genomic aberrations and mutational processes driving PMME and suggested for the first time that PMME may share similar genomic patterns with SKCM; therefore, patients with rare melanomas, such as PMME, may benefit from the current treatment used for common cutaneous melanoma.

p53 positively regulates the proliferation of hepatic progenitor cells promoted by laminin-521

Hepatic progenitor cells (HPCs) hold tremendous potential for liver regeneration, but their well-known limitation of proliferation hampers their broader use. There is evidence that laminin is required for the proliferation of HPCs, but the laminin isoform that plays the dominant role and the key intracellular downstream targets that mediate the regulation of HPC proliferation have yet to be determined. Here we showed that p53 expression increased gradually and reached maximal levels around 8 days when laminin α4, α5, β2, β1, and γ1 subunit levels also reached a maximum during HPC activation and expansion. Laminin-521 (LN-521) promoted greater proliferation of HPCs than do laminin, matrigel or other laminin isoforms. Inactivation of p53 by PFT-α or Ad-p53^V143A inhibited the promotion of proliferation by LN-521. Further complementary MRI and bioluminescence imaging analysis showed that p53 inactivation decreased the proliferation of transplanted HPCs in vivo. p53 was activated by LN-521 through the Integrin α6β1/FAK-Src-Paxillin/Akt axis. Activated p53 was involved in the nuclear translocation of CDK4 and inactivation of Rb by inducing p27^Kip1. Taken together, this study identifies LN-521 as an ideal candidate substrate for HPC culture and uncovers an unexpected positive role for p53 in regulating proliferation of HPCs, which makes it a potential target for HPC-based regenerative medicine.

Transcription-associated DNA DSBs activate p53 during hiPSC-based neurogenesis

Neurons are overproduced during cerebral cortical development. Neural progenitor cells (NPCs) divide rapidly and incur frequent DNA double-strand breaks (DSBs) throughout cortical neurogenesis. Although half of the neurons born during neurodevelopment die, many neurons with inaccurate DNA repair survive leading to brain somatic mosaicism. Recurrent DNA DSBs during neurodevelopment are associated with both gene expression level and gene length. We used imaging flow cytometry and a genome-wide DNA DSB capture approach to quantify and map DNA DSBs during human induced pluripotent stem cell (hiPSC)-based neurogenesis. Reduced p53 signaling was brought about by knockdown (p53KD); p53KD led to elevated DNA DSB burden in neurons that was associated with gene expression level but not gene length in neural progenitor cells (NPCs). Furthermore, DNA DSBs incurred from transcriptional, but not replicative, stress lead to p53 activation in neurotypical NPCs. In p53KD NPCs, DNA DSBs accumulate at transcription start sites of genes that are associated with neurological and psychiatric disorders. These findings add to a growing understanding of how neuronal genome dynamics are engaged by high transcriptional or replicative burden during neurodevelopment.

An atlas of endogenous DNA double-strand breaks arising during human neural cell fate determination

Endogenous DNA double-strand breaks (DSBs) occurring in neural cells have been implicated in the pathogenesis of neurodevelopmental disorders (NDDs). Currently, a genomic map of endogenous DSBs arising during human neurogenesis is missing. Here, we applied in-suspension Breaks Labeling In Situ and Sequencing (sBLISS), RNA-Seq, and Hi-C to chart the genomic landscape of DSBs and relate it to gene expression and genome architecture in 2D cultures of human neuroepithelial stem cells (NES), neural progenitor cells (NPC), and post-mitotic neural cells (NEU). Endogenous DSBs were enriched at the promoter and along the gene body of transcriptionally active genes, at the borders of topologically associating domains (TADs), and around chromatin loop anchors. NDD risk genes harbored significantly more DSBs in comparison to other protein-coding genes, especially in NEU cells. We provide sBLISS, RNA-Seq, and Hi-C datasets for each differentiation stage, and all the scripts needed to reproduce our analyses. Our datasets and tools represent a unique resource that can be harnessed to investigate the role of genome fragility in the pathogenesis of NDDs.

Xenogenic Neural Stem Cell-Derived Extracellular Nanovesicles Modulate Human Mesenchymal Stem Cell Fate and Reconstruct Metabolomic Structure

Extracellular nanovesicles, particularly exosomes, can deliver their diverse bioactive biomolecular content, including miRNAs, proteins, and lipids, thus providing a context for investigating the capability of exosomes to induce stem cells toward lineage-specific cells and tissue regeneration. In this study, it is demonstrated that rat subventricular zone neural stem cell-derived exosomes (rSVZ-NSCExo) can control neural-lineage specification of human mesenchymal stem cells (hMSCs). Microarray analysis shows that the miRNA content of rSVZ-NSCExo is a faithful representation of rSVZ tissue. Through immunocytochemistry, gene expression, and multi-omics analyses, the capability to use rSVZ-NSCExo to induce hMSCs into a neuroglial or neural stem cell phenotype and genotype in a temporal and dose-dependent manner via multiple signaling pathways is demonstrated. The current study presents a new and innovative strategy to modulate hMSCs fate by harnessing the molecular content of exosomes, thus suggesting future opportunities for rSVZ-NSCExo in nerve tissue regeneration.

Putative Roles of SETBP1 Dosage on the SET Oncogene to Affect Brain Development

Mutations in SET BINDING PROTEIN 1 (SETBP1) cause two different clinically distinguishable diseases called Schinzel–Giedion syndrome (SGS) or SETBP1 deficiency syndrome (SDD). Both disorders are disorders of protein dosage, where SGS is caused by decreased rate of protein breakdown due to mutations in a proteosome targeting domain, and SDD is caused by heterozygous loss-of-function mutations leading to haploinsufficiency. While phenotypes of affected individuals support a role for SETBP1 in brain development, little is known about the mechanisms that might underlie this. The binding partner which gave SETBP1 its name is SET and there is extensive literature on this important oncogene in non-neural tissues. Here we describe different molecular complexes in which SET is involved as well as the role of these complexes in brain development. Based on this information, we postulate how SETBP1 protein dosage might influence these SET-containing molecular pathways and affect brain development. We examine the roles of SET and SETBP1 in acetylation inhibition, phosphatase activity, DNA repair, and cell cycle control. This work provides testable hypotheses for how altered SETBP1 protein dosage affects brain development.

Tracing the origins of glioblastoma by investigating the role of gliogenic and related neurogenic genes/signaling pathways in GBM development: a systematic review

Background

Glioblastoma is one of the most aggressive tumors. The etiology and the factors determining its onset are not yet entirely known. This study investigates the origins of GBM, and for this purpose, it focuses primarily on developmental gliogenic processes. It also focuses on the impact of the related neurogenic developmental processes in glioblastoma oncogenesis. It also addresses why glial cells are at more risk of tumor development compared to neurons.

Methods

Databases including PubMed, MEDLINE, and Google Scholar were searched for published articles without any date restrictions, involving glioblastoma, gliogenesis, neurogenesis, stemness, neural stem cells, gliogenic signaling and pathways, neurogenic signaling and pathways, and astrocytogenic genes.

Results

The origin of GBM is dependent on dysregulation in multiple genes and pathways that accumulatively converge the cells towards oncogenesis. There are multiple layers of steps in glioblastoma oncogenesis including the failure of cell fate-specific genes to keep the cells differentiated in their specific cell types such as p300, BMP, HOPX, and NRSF/REST. There are genes and signaling pathways that are involved in differentiation and also contribute to GBM such as FGFR3, JAK-STAT, and hey1. The genes that contribute to differentiation processes but also contribute to stemness in GBM include notch, Sox9, Sox4, c-myc gene overrides p300, and then GFAP, leading to upregulation of nestin, SHH, NF-κB, and others. GBM mutations pathologically impact the cell circuitry such as the interaction between Sox2 and JAK-STAT pathway, resulting in GBM development and progression.

Conclusion

Glioblastoma originates when the gene expression of key gliogenic genes and signaling pathways become dysregulated. This study identifies key gliogenic genes having the ability to control oncogenesis in glioblastoma cells, including p300, BMP, PAX6, HOPX, NRSF/REST, LIF, and TGF beta. It also identifies key neurogenic genes having the ability to control oncogenesis including PAX6, neurogenins including Ngn1, NeuroD1, NeuroD4, Numb, NKX6-1 Ebf, Myt1, and ASCL1. This study also postulates how aging contributes to the onset of glioblastoma by dysregulating the gene expression of NF-κB, REST/NRSF, ERK, AKT, EGFR, and others.

Generation of Human iPSC-Derived Astrocytes with a mature star-shaped phenotype for CNS modeling

The generation of astrocytes from human induced pluripotent stem cells has been hampered by either prolonged differentiation—spanning over two months—or by shorter protocols that generate immature astrocytes, devoid of salient mature astrocytic traits pivotal for central nervous system (CNS) modeling. We directed stable hiPSC-derived neuroepithelial stem cells to human iPSC-derived Astrocytes (hiAstrocytes) with a high percentage of star-shaped cells by orchestrating an astrocytic-tuned culturing environment in 28 days. We employed RT-qPCR and ICC to validate the astrocytic commitment of the neuroepithelial stem cells. To evaluate the inflammatory phenotype, we challenged the hiAstrocytes with the pro-inflammatory cytokine IL-1β (interleukin 1 beta) and quantitatively assessed the secretion profile of astrocyte-associated cytokines and the expression of intercellular adhesion molecule 1 (ICAM-1). Finally, we quantitatively assessed the capacity of hiAstrocytes to synthesize and export the antioxidant glutathione. In under 28 days, the generated cells express canonical and mature astrocytic markers, denoted by the expression of GFAP, AQP4 and ALDH1L1. In addition, the notion of a mature phenotype is reinforced by the expression of both astrocytic glutamate transporters EAAT1 and EAAT2. Thus, hiAstrocytes have a mature phenotype that encompasses traits critical in CNS modeling, including glutathione synthesis and secretion, upregulation of ICAM-1 and a cytokine secretion profile on a par with human fetal astrocytes. This protocol generates a multifaceted astrocytic model suitable for in vitro CNS disease modeling and personalized medicine.

DNA Double-Strand Breaks as Pathogenic Lesions in Neurological Disorders

The damage and repair of DNA is a continuous process required to maintain genomic integrity. DNA double-strand breaks (DSBs) are the most lethal type of DNA damage and require timely repair by dedicated machinery. DSB repair is uniquely important to nondividing, post-mitotic cells of the central nervous system (CNS). These long-lived cells must rely on the intact genome for a lifetime while maintaining high metabolic activity. When these mechanisms fail, the loss of certain neuronal populations upset delicate neural networks required for higher cognition and disrupt vital motor functions. Mammalian cells engage with several different strategies to recognize and repair chromosomal DSBs based on the cellular context and cell cycle phase, including homologous recombination (HR)/homology-directed repair (HDR), microhomology-mediated end-joining (MMEJ), and the classic non-homologous end-joining (NHEJ). In addition to these repair pathways, a growing body of evidence has emphasized the importance of DNA damage response (DDR) signaling, and the involvement of heterogeneous nuclear ribonucleoprotein (hnRNP) family proteins in the repair of neuronal DSBs, many of which are linked to age-associated neurological disorders. In this review, we describe contemporary research characterizing the mechanistic roles of these non-canonical proteins in neuronal DSB repair, as well as their contributions to the etiopathogenesis of selected common neurological diseases.

The neurodevelopmental disorders associated gene Rnf113a regulates survival and differentiation properties of neural stem cells

RNF113A (Ring Finger Protein 113A) is genetically associated with autism spectrum disorders and X-linked trichothiodystrophy (TTD) syndrome. Loss-of-function mutations in human RNF113A are causally linked to TTD, which is characterized by abnormal development of central nervous system (CNS) and mental retardation. How loss of RNF113A activity affects brain development is not known. Here we identify Rnf113a1 as a critical regulator of cell death and neurogenesis during mouse brain development. Rnf113a1 gene exhibits widespread expression in the embryonic CNS. Knockdown studies in embryonic cortical neural stem/progenitor cells (NSCs) and the mouse cortex suggest that Rnf113a1 controls survival, proliferation and differentiation properties of progenitor cells. Importantly, Rnf113a1 deficiency triggers cell apoptosis via a combined action on essential regulators of cell survival, including p53, Nupr1 and Rad51. Collectively, these observations establish Rnf113a1 as a regulatory factor in CNS development and provide insights for its role in neurodevelopmental defects associated with TTD and autism.

The Relationship between p53-Positive Neurons and Dark Neurons in the Hippocampus of Rats after Surgical Interventions on the Nasal Septum

The study evaluates the dependence of p53 protein expression on the appearance of dark neurons (DNs) in the hippocampus in rats during experimental modeling of septoplasty. Septoplasty simulation was carried out on 15 sexually mature male Wistar rats. We studied histological sections of the hippocampus stained with Nissl toluidine blue and antibodies to the p53 protein. In the CA1 subfield, the number of p53-positive neurons significantly increased on the 2nd, 4th (p < 0.001) and 6th days (p < 0.05). In the dynamics, the peak of the growth of p53 protein expression in the cytoplasm of CA1 and CA2 neurons fell on the 2-4th day after the operation, and on the 6th day the number of these neurons decreased (p < 0.001). In the cytoplasm of CA3 neurons in all periods after surgery, an increase in the expression of the p53 protein as compared to the control group was noted. In the CA1 pyramidal layer, the number of DNs decreased on the 6th day (p < 0.001). In CA2, after 2 days, a minimum of DNs as compared with the 4th day (p < 0.001) was noted. In CA3, on the 4th day, there was a peak in DNs as compared with the rest of the days (p < 0.001). A positive strong association was found in all periods of assessment and in all subfields of the hippocampus between an increase in the number of dark and p53-positive neurons. The appearance of dark and p53-positive neurons in the hippocampal formation in rats after simulating septoplasty are typical responses of nervous tissue to stress. It is obvious that the expression of the p53 protein is associated with the basophilia of the cytoplasm of neurons, their morpho-functional state. Presumably, the p53 protein can trigger not only the activation of damaged neurons in the hippocampus but also play a neuroprotective role. Upcoming studies should determine the role of the p53 protein in the further fate of damaged neurons in the pyramidal layer and differentiate the mechanisms of its expression.

Multifaceted roles of YEATS domain-containing proteins and novel links to neurological diseases

The so-called Yaf9, ENL, AF9, Taf14, and Sas5 (YEATS) domain-containing proteins, hereafter referred to as YD proteins, take control over the transcription by multiple steps of regulation either involving epigenetic remodelling of chromatin or guiding the processivity of RNA polymerase II to facilitate elongation-coupled mRNA 3' processing. Interestingly, an increasing amount of evidence suggest a wider repertoire of YD protein's functions spanning from non-coding RNA regulation, RNA-binding proteins networking, post-translational regulation of a few signalling transduction proteins and the spindle pole formation. However, such a large set of non-canonical roles is still poorly characterized. Notably, four paralogous of human YEATS domain family members, namely eleven-nineteen-leukaemia (ENL), ALL1-fused gene from chromosome 9 protein (AF9), YEATS2 and glioma amplified sequence 41 (GAS41), have a strong link to cancer yet new findings also highlight a potential novel role in neurological diseases. Here, in an attempt to more comprehensively understand the complexity of four YD proteins and to gain more insight into the novel functions they may accomplish in the neurons, we summarized the YD protein's networks, systematically searched and reviewed the YD genetic variants associated with neurodevelopmental disorders and finally interrogated the model organism Drosophila melanogaster.

TP53 promotes lineage commitment of human embryonic stem cells through ciliogenesis and sonic hedgehog signaling

Aneuploidy, defective differentiation, and inactivation of the tumor suppressor TP53 all occur frequently during tumorigenesis. Here, we probe the potential links among these cancer traits by inactivating TP53 in human embryonic stem cells (hESCs). TP53-/- hESCs exhibit increased proliferation rates, mitotic errors, and low-grade structural aneuploidy; produce poorly differentiated immature teratomas in mice; and fail to differentiate into neural progenitor cells (NPCs) in vitro. Genome-wide CRISPR screen reveals requirements of ciliogenesis and sonic hedgehog (Shh) pathways for hESC differentiation into NPCs. TP53 deletion causes abnormal ciliogenesis in neural rosettes. In addition to restraining cell proliferation through CDKN1A, TP53 activates the transcription of BBS9, which encodes a ciliogenesis regulator required for proper Shh signaling and NPC formation. This developmentally regulated transcriptional program of TP53 promotes ciliogenesis, restrains Shh signaling, and commits hESCs to neural lineages.

Anti-Oxidative, Anti-Inflammatory and Anti-Apoptotic Effects of Flavonols: Targeting Nrf2, NF-κB and p53 Pathways in Neurodegeneration

Neurodegenerative diseases are one of the leading causes of disability and death worldwide. Intracellular transduction pathways that end in the activation of specific transcription factors are highly implicated in the onset and progression of pathological changes related to neurodegeneration, of which those related to oxidative stress (OS) and neuroinflammation are particularly important. Here, we provide a brief overview of the key concepts related to OS- and neuroinflammation-mediated neuropathological changes in neurodegeneration, together with the role of transcription factors nuclear factor erythroid 2-related factor 2 (Nrf2) and nuclear factor-κB (NF-κB). This review is focused on the transcription factor p53 that coordinates the cellular response to diverse genotoxic stimuli, determining neuronal death or survival. As current pharmacological options in the treatment of neurodegenerative disease are only symptomatic, many research efforts are aimed at uncovering efficient disease-modifying agents. Natural polyphenolic compounds demonstrate powerful anti-oxidative, anti-inflammatory and anti-apoptotic effects, partially acting as modulators of signaling pathways. Herein, we review the current understanding of the therapeutic potential and limitations of flavonols in neuroprotection, with emphasis on their anti-oxidative, anti-inflammatory and anti-apoptotic effects along the Nrf2, NF-κB and p53 pathways. A better understanding of cellular and molecular mechanisms of their action may pave the way toward new treatments.

Role of JNK and p53 in Implementation of Functions of Various Types of Regeneration-Competent Cells of the Nervous Tissue

We studied the participation of JNK and p53 in the realization of the growth potential of different types of progenitors of the subventricular zone of mouse brain and secretion of neurotrophins by glial cells. The stimulating role of these signaling molecules in mitotic activity and specialization of multipotent neural stem cells was shown. It was found that JNK and p53 do not participate in the regulation of committed neuronal progenitor cells (clonogenic PSA-NCAM⁺ cells). A dependence of neurotrophic growth factors in individual populations of neuroglia on activity of these protein kinase and transcription factor was revealed. The role of JNK and p53 in astrocytes consists in stimulation of their secretion, and in microglial cells, on the contrary, in its inhibition. The secretory neurotrophic function of oligodendrogliocytes is not associated with JNK and p53 activity.

Applications of brain organoids in neurodevelopment and neurological diseases

A brain organoid is a self-organizing three-dimensional tissue derived from human embryonic stem cells or pluripotent stem cells and is able to simulate the architecture and functionality of the human brain. Brain organoid generation methods are abundant and continue to improve, and now, an in vivo vascularized brain organoid has been encouragingly reported. The combination of brain organoids with immune-staining and single-cell sequencing technology facilitates our understanding of brain organoids, including the structural organization and the diversity of cell types. Recent publications have reported that brain organoids can mimic the dynamic spatiotemporal process of early brain development, model various human brain disorders, and serve as an effective preclinical platform to test and guide personalized treatment. In this review, we introduce the current state of brain organoid differentiation strategies, summarize current progress and applications in the medical domain, and discuss the challenges and prospects of this promising technology.

Increased p53 signaling impairs neural differentiation in HUWE1-promoted intellectual disabilities

Essential E3 ubiquitin ligase HUWE1 (HECT, UBA, and WWE domain containing 1) regulates key factors, such as p53. Although mutations in HUWE1 cause heterogenous neurodevelopmental X-linked intellectual disabilities (XLIDs), the disease mechanisms common to these syndromes remain unknown. In this work, we identify p53 signaling as the central process altered in HUWE1-promoted XLID syndromes. By focusing on Juberg-Marsidi syndrome (JMS), one of the severest XLIDs, we show that increased p53 signaling results from p53 accumulation caused by HUWE1 p.G4310R destabilization. This further alters cell-cycle progression and proliferation in JMS cells. Modeling of JMS neurodevelopment reveals majorly impaired neural differentiation accompanied by increased p53 signaling. The neural differentiation defects can be successfully rescued by reducing p53 levels and restoring the expression of p53 target genes, in particular CDKN1A/p21. In summary, our findings suggest that increased p53 signaling underlies HUWE1-promoted syndromes and impairs XLID JMS neural differentiation.

Broadly Active Antiviral Compounds Disturb Zika Virus Progeny Release Rescuing Virus-Induced Toxicity in Brain Organoids

RNA viruses have gained plenty of attention during recent outbreaks of Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), Zika virus (ZIKV), and Ebola virus. ZIKV is a vector borne Flavivirus that is spread by mosquitoes and it mainly infects neuronal progenitor cells. One hallmark of congenital ZIKV disease is a reduced brain size in fetuses, leading to severe neurological defects. The World Health Organization (WHO) is urging the development of new antiviral treatments against ZIKV, as there are no efficient countermeasures against ZIKV disease. Previously, we presented a new class of host-targeting antivirals active against a number of pathogenic RNA viruses, such as SARS-CoV-2. Here, we show the transfer of the image-based phenotypic antiviral assay to ZIKV-infected brain cells, followed by mechanism-of-action studies and a proof-of-concept study in a three-dimensional (3D) organoid model. The novel antiviral compounds showed a therapeutic window against ZIKV in several cell models and rescued ZIKV-induced neurotoxicity in brain organoids. The compound’s mechanism-of-action was pinpointed to late steps in the virus life cycle, impairing the formation of new virus particles. Collectively, in this study, we expand the antiviral activity of new small molecule inhibitors to a new virus class of Flaviviruses, but also uncover compounds’ mechanism of action, which are important for the further development of antivirals.

p53 coordinates glucose and choline metabolism during the mesendoderm differentiation of human embryonic stem cells

Metabolism plays crucial roles in the fate decision of human embryonic stem cells (hESCs). Here, we show that the depletion of p53 in hESCs enhances glycolysis and reduces oxidative phosphorylation, and delays mesendoderm differentiation of hESCs. More intriguingly, the disruption of p53 in hESCs leads to dramatic upregulation of phosphatidylcholine and decrease of total choline in both pluripotent and differentiated state of hESCs, suggesting abnormal choline metabolism in the absence of p53. Collectively, our study reveals the indispensable role of p53 in orchestrating both glucose and lipid metabolism to maintain proper hESC identity.

A Glance of p53 Functions in Brain Development, Neural Stem Cells, and Brain Cancer

p53 is one of the most intensively studied tumor suppressors. It transcriptionally regulates a broad range of genes to modulate a series of cellular events, including DNA damage repair, cell cycle arrest, senescence, apoptosis, ferroptosis, autophagy, and metabolic remodeling, which are fundamental for both development and cancer. This review discusses the role of p53 in brain development, neural stem cell regulation and the mechanisms of inactivating p53 in gliomas. p53 null or p53 mutant mice show female biased exencephaly, potentially due to X chromosome inactivation failure and/or hormone-related gene expression. Oxidative cellular status, increased PI3K/Akt signaling, elevated ID1, and metabolism are all implicated in p53-loss induced neurogenesis. However, p53 has also been shown to promote neuronal differentiation. In addition, p53 mutations are frequently identified in brain tumors, especially glioblastomas. Mechanisms underlying p53 inactivation in brain tumor cells include disruption of p53 protein stability, gene expression and transactivation potential as well as p53 gene loss or mutation. Loss of p53 function and gain-of-function of mutant p53 are both implicated in brain development and tumor genesis. Further understanding of the role of p53 in the brain may provide therapeutic insights for brain developmental syndromes and cancer.

Stem Cells of the Aging Brain

The adult central nervous system (CNS) contains resident stem cells within specific niches that maintain a self-renewal and proliferative capacity to generate new neurons, astrocytes, and oligodendrocytes throughout adulthood. Physiological aging is associated with a progressive loss of function and a decline in the self-renewal and regenerative capacities of CNS stem cells. Also, the biggest risk factor for neurodegenerative diseases is age, and current in vivo and in vitro models of neurodegenerative diseases rarely consider this. Therefore, combining both aging research and appropriate interrogation of animal disease models towards the understanding of the disease and age-related stem cell failure is imperative to the discovery of new therapies. This review article will highlight the main intrinsic and extrinsic regulators of neural stem cell (NSC) aging and discuss how these factors impact normal homeostatic functions within the adult brain. We will consider established in vivo animal and in vitro human disease model systems, and then discuss the current and future trajectories of novel senotherapeutics that target aging NSCs to ameliorate brain disease.