Rapamycin mitigates Valproic Acid-induced teratogenicity in human and animal models by suppressing AP-1-mediated senescence
Ontology highlight
ABSTRACT: Valproic acid (VPA) is an effective and widely used anti-seizure medication but is teratogenic when used during pregnancy, affecting brain and spinal cord development for reasons that remain largely unclear. Here we designed a genetic recombinase-based SOX10 reporter system in human pluripotent stem cells that enables tracking and lineage tracing of Neural Crest cells (NCCs) in a human organoid model of the developing neural tube. We found that VPA induces extensive cellular senescence and promotes mesenchymal differentiation of human NCCs at the expense of neural lineages. We next show that the clinically-approved drug, Rapamycin, inhibits AP1-mediated senescence and restores aberrant NCC differentiation trajectory in human organoids exposed to VPA. Notably, in vivo validation in developing zebrafish highlighted the therapeutic promise of this approach. Collectively our data identifies a novel mechanism for VPA-associated neurodevelopmental teratogenicity and a potential pharmacological preventative strategy. The results exemplify the power of genetically modified human stem cell-derived organoid models for drug discovery and safety testing.
Project description:Valproic acid (VPA) is a potent inducer of neural tube defects (ntd:s) in both human and mouse, but its mechanism of teratogenicity is not know. The mouse embryonic stem cell line R1, may be relevant as an in vitro model of teratogenicity and was evaluated with exposures to VPA,and the two VPA anlogs (S)-2-pentyl-4-pentynoic acid, and 2-ethyl-4-methyl-pentanoic acid to profile the gene expression response. Those profiles may reveal biomarkers of teratogenic exposures in an in vitro system as well as give mechanistic input of the teratogenicity of VPA.
Project description:In the process of evaluating teratogenic properties of xenobiotica, the consumption of laboratory animals is high and costly which makes the development of alternative methods desirable. The pluripotent embryocarcinoma cell line P19, which closely resembles the early stage of an embryo, may be relevant as an in vitro model of teratogenicity. The antiepileptic drug Valproic acid (VPA) is a potent inducer of neural tube defects (ntd:s) in both human and mouse, but its mechanism of teratogenicity is not know. P19 cells were here treated with sodium valproate in a both time and dose dependent matter to profile the gene expression response with Codelink UniSet Mouse 20K I Bioarrays. This profile may reveal biomarkers of ntd:s as well as give mechanistic input of the teratogenicity of VPA.
Project description:Valproic acid (VPA) is a potent inducer of neural tube defects (NTDs), but its mechanism of teratogenicity is not known. To study the transcriptional response of VPA during the susceptible period, i.e. when VPA is likely to exert most of its teratogenic effect, RNA was extracted from 8.25-dpc embryos (6 h post treatment) from control and VPA-treated dams, and subjected to microarray analysis (four arrays). To be more useful for risk assessment, in vitro models, using cells, may bridge biomarkers discovered by gene expression profiling in an animal in vivo model. Since pluripotent embryocarcinoma (EC) cell lines may be relevant models for early embryonic cells, P19 mouse EC cells were treated with or without 1 mM sodium valproate for 24 h and alos subjected to microarray analysis (four arrays).
Project description:Neural tube defects (NTDs) including anencephaly and spina bifida are common major malformations of fetal development resulting from incomplete closure of the neural tube. These conditions lead to either universal death (anencephaly) or life-long severe complications (spina bifida). Despite hundreds of genetic mouse models having neural tube defect phenotypes, the genetics of human NTDs are poorly understood. Furthermore, pharmaceuticals such as antiseizure medications have been found clinically to increase the risk of NTDs when administered during pregnancy. Therefore, a model that recapitulates human neurodevelopment would be of immense benefit to understand the genetics underlying NTDs and identify teratogenic mechanisms. Using our self-organizing single rosette spheroid (SOSRS) brain organoid system, we have developed a high-throughput image analysis pipeline for evaluating SOSRS structure for NTD-like phenotypes. Similar to small molecule inhibition of apical constriction, the antiseizure medication valproic acid (VPA), a known cause of NTDs, increases the apical lumen size and apical cell surface area in a dose-responsive manner. This expansion was mimicked by GSK3b and HDAC inhibitors; however, RNA sequencing suggests VPA does not inhibit GSK3b at these concentrations. Knockout of SHROOM3, a well-known NTD-related gene, also caused expansion of the lumen as well as reduced f-actin polarization. The increased lumen sizes were caused by reduced cell apical constriction suggesting that impingement of this process is a shared mechanism for VPA treatment and SHROOM3-KO, two well-known causes of NTDs. Our system allows the rapid identification of NTD-like phenotypes for both compounds and genetic variants and should prove useful for understanding specific NTD mechanisms and predicting drug teratogenicity.
Project description:Human pluripotent stem cells can be rapidly converted into functional neurons by ectopic expression of proneural transcription factors. Here we show that directly reprogrammed neurons, despite their rapid maturation kinetics, can model teratogenic mechanisms that specifically affect early neurodevelopment. We delineated distinct phases of in vitro maturation during reprogramming of human neurons and assessed the cellular phenotypes of valproic acid (VPA), a teratogenic drug. VPA exposure caused chronic impairment of dendritic morphology and functional properties of developing neurons, but not those of mature neurons. These pathogenic effects were associated with VPA-mediated inhibition of the histone deacetylase (HDAC) and glycogen synthase kinase-3 (GSK-3) pathways, which caused transcriptional downregulation of many genes, including MARCKSL1, an actin-stabilizing protein essential for dendritic morphogenesis and synapse maturation during early neurodevelopment. Our findings identify a developmentally restricted pathogenic mechanism of VPA and establish the use of reprogrammed neurons as an effective platform for modeling teratogenic pathways.
Project description:In order to more thoroughly investigate the mechanism of arsenate-induced NTDs we designed experiment in which highly sensitive Folr2 nullizygous mice were treated i.p. with teratogenic dose of sodium arsenate just at the beginning of the neural tube formation process. This specific knockout mouse and arsenic exposure conditions were chosen as they warranted high incidence of exencephaly in exposed embryos. We investigated the gene expression changes induced by arsenic in the anterior part of neural tube in order to discover patterns that might shed light on the mechanism of arsenic’s teratogenicity. Keywords: toxic response
Project description:The aim of this study was the development of an alternative testing method based on human embryonic stem cells for prenatal developmental toxicity with particular emphasis on early neural development. To this purpose, we designed an in vitro protocol based on the generation of neural rosettes, representing the in vitro counterpart of the developing neural plate and neural tube, and we challenged this complex cell model with retinoic acid (RA), a well-known teratogenic agent. The cells were exposed to different concentrations of RA during the process of rosettes formation. Morphological and molecular parameters were evaluated in treated as compared with untreated cells to detect both cytotoxicity and specific neural toxicity. Transcriptomic analysis was performed with microarray Affymetrix platform and validated by quantitative real-time PCR for genes relevant to early neural development such as HoxA1, HoxA3, HoxB1, HoxB4, FoxA2, FoxC1, Otx2, and Pax7. The results obtained demonstrated that neural rosette forming cells respond to RA with clear concentration-dependent morphological, and gene expression changes remarkably similar to those induced in vivo, in the developing neural tube, by RA exposure. This strict correspondence indicates that the neural rosette protocol described is capable of detecting specific teratogenic mechanisms causing perturbations of early neural development and therefore represents a promising alternative test for human prenatal developmental toxicity.
Project description:The human cerebral cortex possess distinct structural and functional features that are not found in the lower species traditionally used to model brain development and disease. Accordingly, considerable attention has been placed on the development of methods to direct pluripotency stem cells to form human brain-like structures termed organoids. However, many organoid differentiation protocols are inefficient and display marked variability in their ability to recapitulate the three-dimensional architecture and course of neurogenesis in the developing human brain. Here, we report optimized organoid culture methods that efficiently and reliably produce cortical and basal ganglia structures similar to those in the human fetal brain in vivo. Neurons within the organoids are functional and exhibit network-like activities. We further demonstrate the utility of the organoid system for modeling the teratogenic effects of Zika virus on the developing brain and identifying new candidate receptors and therapeutic compounds that can mitigate its desructive actions.
Project description:The human cerebral cortex possess distinct structural and functional features that are not found in the lower species traditionally used to model brain development and disease. Accordingly, considerable attention has been placed on the development of methods to direct pluripotency stem cells to form human brain-like structures termed organoids. However, many organoid differentiation protocols are inefficient and display marked variability in their ability to recapitulate the three-dimensional architecture and course of neurogenesis in the developing human brain. Here, we report optimized organoid culture methods that efficiently and reliably produce cortical and basal ganglia structures similar to those in the human fetal brain in vivo. Neurons within the organoids are functional and exhibit network-like activities. We further demonstrate the utility of the organoid system for modeling the teratogenic effects of Zika virus on the developing brain and identifying new candidate receptors and therapeutic compounds that can mitigate its desructive actions.
Project description:Neural crest cells (NCCs) are vertebrate stem cells that give rise to various cell types throughout the developing body in early life. Here, we utilized single-cell transcriptomic analyses to delineate NCC-derivatives along the posterior developing vertebrate, zebrafish, during the late embryonic to early larval stage, a period when NCCs are actively differentiating into distinct cellular lineages. We identified several major NCC/NCC-derived cell-types including mesenchyme, neural crest, neural, neuronal, glial, and pigment, from which we resolved over three dozen cellular subtypes. We dissected gene expression signatures of pigment progenitors delineating into chromatophore lineages, mesenchyme subtypes, and enteric NCCs transforming into enteric neurons. Global analysis of NCC derivatives revealed they were demarcated by combinatorial hox gene codes, with distinct profiles within neuronal cells. From these analyses, we present a comprehensive cell-type atlas that can be utilized as a valuable resource for further mechanistic and evolutionary investigations of NCC differentiation.