Project description:Individuals with disruptions in the Autism Susceptibility Candidate 2 (AUTS2) gene frequently exhibit symptoms like intellectual disability, microcephaly, growth retardation, and distinct skeletal and facial differences. The role of AUTS2 in neurodevelopment has been explored using animal models and in vitro embryonic stem cell models. However, the precise molecular mechanisms through which AUTS2 influences neurodevelopment, particularly in humans, are not thoroughly understood. To address this, our study employs a 3D human organoid culture system, in combination with genetic, genomic, cellular, and molecular approaches, to investigate how AUTS2 impacts neurodevelopment through cellular signaling pathways. We used CRISPR/Cas9 technology to create AUTS2-deficient human embryonic stem cells (hESCs), replicating a 190kb genetic deletion observed in a patient. These cells were then differentiated into cerebral organoids. Our single-cell RNA sequencing (scRNA-seq) analysis of these organoids indicates that the absence of AUTS2 results in a significant reduction in neuron-related cells and an increase in choroid plexus (ChP) epithelial cells. Notably, our research reveals that AUTS2 negatively regulates the Wnt/β-catenin signaling pathway, evidenced by the observed overactivation of this pathway in AUTS2-deficient organoids as well as in a luciferase reporter cell line with AUTS2 deletion. Importantly, treating the AUTS2-deficient cerebral organoids with a Wnt inhibitor ameliorated the abnormalities in neuronal differentiation. This study offers new insights into the role of AUTS2 in neurodevelopment and suggests new potential targeted therapies for NDDs.
Project description:Individuals with disruptions in the Autism Susceptibility Candidate 2 (AUTS2) gene frequently exhibit symptoms like intellectual disability, microcephaly, growth retardation, and distinct skeletal and facial differences. The role of AUTS2 in neurodevelopment has been explored using animal models and in vitro embryonic stem cell models. However, the precise molecular mechanisms through which AUTS2 influences neurodevelopment, particularly in humans, are not thoroughly understood. To address this, our study employs a 3D human organoid culture system, in combination with genetic, genomic, cellular, and molecular approaches, to investigate how AUTS2 impacts neurodevelopment through cellular signaling pathways. We used CRISPR/Cas9 technology to create AUTS2-deficient human embryonic stem cells (hESCs), replicating a 190kb genetic deletion observed in a patient. These cells were then differentiated into cerebral organoids. Our single-cell RNA sequencing (scRNA-seq) analysis of these organoids indicates that the absence of AUTS2 results in a significant reduction in neuron-related cells and an increase in choroid plexus (ChP) epithelial cells. Notably, our research reveals that AUTS2 negatively regulates the Wnt/β-catenin signaling pathway, evidenced by the observed overactivation of this pathway in AUTS2-deficient organoids as well as in a luciferase reporter cell line with AUTS2 deletion. Importantly, treating the AUTS2-deficient cerebral organoids with a Wnt inhibitor ameliorated the abnormalities in neuronal differentiation. This study offers new insights into the role of AUTS2 in neurodevelopment and suggests new potential targeted therapies for NDDs.
Project description:On pathological stress, Wnt signaling is reactivated and induces genes associated with cardiac remodeling and fibrosis. We have previously shown that a cell surface receptor Cdon (cell-adhesion associated, oncogene regulated) suppresses Wnt signaling to promote neuronal differentiation however its role in heart is unknown. Here, we demonstrate a critical role of Cdon in cardiac function and remodeling. Cdon is expressed and predominantly localized at intercalated disk in both mouse and human hearts. Cdon-deficient mice develop cardiac dysfunction including reduced ejection fraction and ECG abnormalities. Cdon-/- hearts exhibit increased fibrosis and up-regulation of genes associated with cardiac remodeling and fibrosis. Electrical remodeling was demonstrated by up-regulation and mislocalization of the gap junction protein, Connexin 43 (Cx43) in Cdon-/- hearts. In agreement with altered Cx43 expression, functional analysis both using Cdon-/- cardiomyocytes and shRNA-mediated knockdown in rat cardiomyocytes shows aberrant gap junction activities. Analysis of the underlying mechanism reveals that Cdon-/- hearts exhibit hyperactive Wnt signaling as evident by β-catenin accumulation and Axin2 up-regulation. On the other hand, the treatment of rat cardiomyocytes with a Wnt activator TWS119 reduces Cdon levels and aberrant Cx43 activities, similarly to Cdon-deficient cardiomyocytes, suggesting a negative feedback between Cdon and Wnt signaling. Finally, inhibition of Wnt/β-catenin signaling by XAV939, IWP2 or dickkopf (DKK)1 prevented Cdon depletion-induced up-regulation of collagen 1a and Cx43. Taken together, these results demonstrate that Cdon deficiency causes hyperactive Wnt signaling leading to aberrant intercellular coupling and cardiac fibrosis. Cdon exhibits great potential as a target for the treatment of cardiac fibrosis and cardiomyopathy.
Project description:Variants in the AUTS2 gene are associated with a broad spectrum of neurological conditions characterized by intellectual disability, microcephaly, and congenital brain malformations. Here, we use a human cerebral organoid model to investigate the pathophysiology of a heterozygous de novo missense AUTS2 variant identified in a patient with multiple neurological impairments including primary microcephaly and profound intellectual disability. Proband cerebral organoids exhibit reduced growth, deficits in neural progenitor cell (NPC) proliferation and disrupted NPC polarity within ventricular zone-like regions compared to control cerebral organoids. We used CRISPR-Cas9-mediated gene editing to correct this variant and demonstrate rescue of impaired organoid growth and NPC proliferative deficits. Single-cell RNA sequencing revealed a marked reduction of G1/S transition gene expression and alterations in WNT-β-catenin signalling within proband NPCs, uncovering a novel role for AUTS2 in NPCs during human cortical development. Collectively, these results underscore the value of cerebral organoids to investigate molecular mechanisms underlying AUTS2 syndrome.
Project description:The development of three-dimensional culture methods has allowed for the study of developing cortical morphology in human cells. This provides a new tool to study the neurodevelopmental consequences of disease-associated mutations. Here, we study the effects of isogenic DISC1 mutation in cerebral organoids. DISC1 has been implicated in psychiatric disease based on genetic studies, including its interruption by a balanced translocation that increases the risk of major mental illness. Isogenic wild-type and DISC1-disrupted human-induced pluripotent stem cells were used to generate cerebral organoids, which were then examined for morphology and gene expression. We show that DISC1-mutant cerebral organoids display disorganized structural morphology and impaired proliferation, which is phenocopied by WNT agonism and rescued by WNT antagonism. Furthermore, there are many shared changes in gene expression with DISC1 disruption and WNT agonism, including in neural progenitor and cell fate markers, regulators of neuronal migration, and interneuron markers. These shared gene expression changes suggest mechanisms for the observed morphologic dysregulation with DISC1 disruption and points to new avenues for future studies. The shared changes in three-dimensional cerebral organoid morphology and gene expression with DISC1 interruption and WNT agonism further strengthens the link between DISC1 mutation, abnormalities in WNT signaling, and neuropsychiatric disease.
Project description:Fine control of Wnt signaling is essential for various cellular and developmental decision-making processes. However, deregulation of Wnt signaling leads to pathological consequences, one of which is cancer. Here, we identify a function of PAF, a component of translesion DNA synthesis, in modulating Wnt signaling. PAF is specifically overexpressed in colon cancer cells and intestinal stem cells and is required for colon cancer cell proliferation. In Xenopus laevis, ventrovegetal expression of PAF hyperactivates Wnt signaling, developing a secondary axis with ?-catenin target gene upregulation. Upon Wnt signaling activation, PAF dissociates from PCNA and binds directly to ?-catenin. Then, PAF recruits EZH2 to the ?-catenin transcriptional complex and specifically enhances Wnt target gene transactivation, independently of EZH2's methyltransferase activity. In mice, conditional expression of PAF induces intestinal neoplasia via Wnt signaling hyperactivation. Our studies reveal an unexpected role of PAF in regulating Wnt signaling and propose a regulatory mechanism of Wnt signaling during tumorigenesis.
Project description:A patient with the PSEN1 E280A mutation and homozygous for APOE3 Christchurch (APOE3Ch) displayed extreme resistance to Alzheimer's disease (AD) cognitive decline and tauopathy, despite having a high amyloid burden. To further investigate the differences in biological processes attributed to APOE3Ch, we generated induced pluripotent stem (iPS) cell-derived cerebral organoids from this resistant case and a non-protected control, using CRISPR/Cas9 gene editing to modulate APOE3Ch expression. In the APOE3Ch cerebral organoids, we observed a protective pattern from early tau phosphorylation. ScRNA sequencing revealed regulation of Cadherin and Wnt signaling pathways by APOE3Ch, with immunostaining indicating elevated β-catenin protein levels. Further in vitro reporter assays unexpectedly demonstrated that ApoE3Ch functions as a Wnt3a signaling enhancer. This work uncovered a neomorphic molecular mechanism of protection of ApoE3 Christchurch, which may serve as the foundation for the future development of protected case-inspired therapeutics targeting AD and tauopathies.
Project description:Disease-related AUTS2 disruption causes an imbalance of neuronal/glial lineage specification through the WNT/β-catenin pathway (RNA-Seq).