An unstable variant of GAP43 leads to neurodevelopmental deficiency.

Growth-associated protein 43 (GAP43) is a membrane-associated phosphoprotein predominantly expressed in the nervous systems, and controls axonal growth, branching, and pathfinding. While the association between GAP43 and human neurological disorders have been reported, the underlying mechanisms remain largely unknown. We performed whole exome sequencing on a patient with intellectual disability (ID), neurodevelopmental disorders, short stature, and skeletal abnormalities such as left-right difference in legs and digital deformities, and identified a heterozygous missense variation in the GAP43 gene [NM_001130064.

The p.R66W Variant in Causes Severe Fetopathy Through Variant-Specific Mechanisms.

encodes a small GTPase of the Rho family that plays a critical role in actin cytoskeleton remodeling and intracellular signaling regulation. Pathogenic variants in , all of which reported thus far affect conserved residues within its functional domains, have been linked to neurodevelopmental disorders characterized by diverse phenotypic features, including structural brain anomalies and facial dysmorphism (NEDBAF). Recently, a novel de novo variant (NM_005052.

Analyses of Neurite and Spine Formation by In Utero Electroporation in Mice.

Dendrite morphology and dendritic spines are key features of the neuronal networks in the brain. Abnormalities in these features have been observed in patients with psychiatric disorders and mouse models of these diseases. In utero electroporation is an easy and efficient gene transfer system for developing mouse embryos in the uterus.

Variations associated with neurodevelopmental disorders affect ARF1 function and cortical development.

ADP-ribosylation factors (ARFs) are a family of small GTPases that regulate vesicle trafficking and actin dynamics in cells. Recent genetic analyses have revealed associations between variations in ARF genes and neurodevelopmental disorders, although their pathophysiological significance remains unclear. In this study, we conducted biochemical, cell biological and in vivo analyses of ARF1 variants linked to neurodevelopmental disorders.

Live Imaging of Migrating Neurons and Glial Progenitors Visualized by in Utero Electroporation.

During cortical development, both neurons and glial cells are generated in the germinal zone near the lateral ventricle, migrate in the correct direction, and settle in their appropriate locations. This developmental process can be clearly visualized by introducing fluorescent protein-expression vectors via in utero electroporation. In this chapter, we describe labeling methods for migrating neurons and glial progenitors, as well as methods for slice culture, and time-lapse imaging.

Simple Method for the Preparation of Postsynaptic Density Fraction from Mouse Brain.

Postsynaptic density (PSD) is a morphologically and functionally specialized postsynaptic membrane structure of excitatory synapses. It contains hundreds of proteins such as neurotransmitter receptors, adhesion molecules, cytoskeletal proteins, and signaling enzymes. The study of the molecular architecture of the PSD is one of the most intriguing issues in neuroscience research.

Analyses of Conditional Knockout Mice for , a Gene Responsible for Neurodevelopmental Disorders in Excitatory and Inhibitory Neurons in the Brain.

POGZ (Pogo transposable element derived with ZNF domain) is known to function as a regulator of gene expression. While variations in the gene have been associated with intellectual disabilities and developmental delays in humans, the exact pathophysiological mechanisms remain unclear. To shed light on this, we created two lines of conditional knockout mice for , one specific to excitatory neurons (Emx1-Pogz mice) and the other to inhibitory neurons (Gad2-Pogz mice) in the brain.

Time-Lapse Imaging of Migrating Neurons and Glial Progenitors in Embryonic Mouse Brain Slices.

During the development of the cerebral cortex, neurons and glial cells originate in the ventricular zone lining the ventricle and migrate toward the brain surface. This process is crucial for proper brain function, and its dysregulation can result in neurodevelopmental and psychiatric disorders after birth. In fact, many genes responsible for these diseases have been found to be involved in this process, and therefore, revealing how these mutations affect cellular dynamics is important for understanding the pathogenesis of these diseases.

Expression analysis of type I ARF small GTPases ARF1-3 during mouse brain development.

Background: ARF (ADP-ribosylation factor) GTPases are major regulators of intracellular trafficking, and classified into 3 groups (Type I - III), among which the type I group members, ARF1 and 3, are responsible genes for neurodevelopmental disorders.

Methods: In this study, we analysed the expression of Type I ARFs ARF1-3 during mouse brain development using biochemical and morphological methods.

Results: Western blotting analyses revealed that ARF1-3 are weakly expressed in the mouse brain at embryonic day 13 and gradually increase until postnatal day 30.

Expression Analyses of C-Terminal-Binding Protein 1 (CtBP1) during Mouse Brain Development.

Introduction: C-terminal-binding protein 1 (CtBP1) is a multi-functional protein with well-established roles as a transcriptional co-repressor in the nucleus and a regulator of membrane fission in the cytoplasm. Although CtBP1 gene abnormalities have been reported to cause neurodevelopmental disorders, the physiological role and expression profile of CtBP1 remains to be elucidated.

Methods: In this study, we used biochemical, immunohistochemical, and immunofluorescence methods to analyze the expression of CtBP1 during mouse brain development.

Expression analyses of WAC, a responsible gene for neurodevelopmental disorders, during mouse brain development.

WAC is an adaptor protein involved in gene transcription, protein ubiquitination, and autophagy. Accumulating evidence indicates that WAC gene abnormalities are responsible for neurodevelopmental disorders. In this study, we prepared anti-WAC antibody, and performed biochemical and morphological characterization focusing on mouse brain development.

Histological Analysis of a Mouse Model of the 22q11.2 Microdeletion Syndrome.

22q11.2 deletion syndrome (22q11.2DS) is associated with a high risk of developing various psychiatric and developmental disorders, including schizophrenia and early-onset Parkinson's disease.

Septin-mediated RhoA activation engages the exocyst complex to recruit the cilium transition zone.

Septins are filamentous GTPases that play important but poorly characterized roles in ciliogenesis. Here, we show that SEPTIN9 regulates RhoA signaling at the base of cilia by binding and activating the RhoA guanine nucleotide exchange factor, ARHGEF18. GTP-RhoA is known to activate the membrane targeting exocyst complex, and suppression of SEPTIN9 causes disruption of ciliogenesis and mislocalization of an exocyst subunit, SEC8.

MED13L and its disease-associated variants influence the dendritic development of cerebral cortical neurons in the mammalian brain.

The mediator complex comprises multiple subcellular subunits that collectively function as a molecular interface between RNA polymerase II and gene-specific transcription factors. Recently, genetic variants to one subunit of the complex, known as MED13L (mediator complex subunit 13 like), have been implicated in syndromic intellectual disability and distinct facial features, frequently accompanied by congenital heart defects. We investigated the impact of five disease-associated MED13L variants on the subcellular localization and biochemical stability of MED13L protein in vitro and in vivo.

Expression Analyses of Rich2/Arhgap44, a Rho Family GTPase-Activating Protein, during Mouse Brain Development.

Rho family small GTPases, such as Rho, Rac, and Cdc42, play essential roles during brain development, by regulating cellular signaling and actin cytoskeletal reorganization. Rich2/Arhgap44, a Rac- and Cdc42-specific GTPase-activating protein, has been reported to be a key regulator for dendritic spine morphology and synaptic function. Given the essential roles of Rac and Cdc42 in brain development, Rich2 is supposed to take part in brain development.

Pathophysiological Mechanism of Neurodevelopmental Disorders-Overview.

Technological advancements in next-generation DNA sequencing have enabled elucidation of many genetic causes of neurodevelopmental disorders (NDDs) over the last two decades [...

Erratic and blood vessel-guided migration of astrocyte progenitors in the cerebral cortex.

Astrocytes are one of the most abundant cell types in the mammalian brain. They play essential roles in synapse formation, maturation, and elimination. However, how astrocytes migrate into the gray matter to accomplish these processes is poorly understood.

Deficiency of , a gene related to intellectual disability, causes impaired neuronal development and a mild behavioural phenotype.

is a gene associated with intellectual disability, which was originally identified as being involved in the maintenance of kinetochore-microtubule attachment. To explore the neuronal defects caused by deficiency, we established mice that lack . Mice that are homozygous knockout for were slightly smaller than wild-type mice and died soon after birth on pure C57BL/6J background.

Expression Analyses of Polo-Like Kinase 4, a Gene Product Responsible for Autosomal Recessive Microcephaly and Seckel Syndrome, during Mouse Brain Development.

Polo-like kinase 4 (Plk4) is a ser/thr kinase, which plays a central role in centriole duplication during the cell cycle. PLK4 gene abnormalities are responsible for autosomal recessive chorioretinopathy-microcephaly syndrome and Seckel syndrome. In this study, we performed expression analyses of Plk4 by focusing on mouse brain development.

Variant-specific changes in RAC3 function disrupt corticogenesis in neurodevelopmental phenotypes.

Variants in RAC3, encoding a small GTPase RAC3 which is critical for the regulation of actin cytoskeleton and intracellular signal transduction, are associated with a rare neurodevelopmental disorder with structural brain anomalies and facial dysmorphism. We investigated a cohort of 10 unrelated participants presenting with global psychomotor delay, hypotonia, behavioural disturbances, stereotyped movements, dysmorphic features, seizures and musculoskeletal abnormalities. MRI of brain revealed a complex pattern of variable brain malformations, including callosal abnormalities, white matter thinning, grey matter heterotopia, polymicrogyria/dysgyria, brainstem anomalies and cerebellar dysplasia.

Gain-of-function p.F28S variant in disrupts neuronal differentiation, migration and axonogenesis during cortical development, leading to neurodevelopmental disorder.

Background: encodes a Rho family small GTPase that regulates the behaviour and organisation of actin cytoskeleton and intracellular signal transduction. Variants in can cause a phenotypically heterogeneous neurodevelopmental disorder with structural brain anomalies and dysmorphic facies. The pathomechanism of this recently discovered genetic disorder remains unclear.

Expression Analyses of Cep152, a Responsible Gene Product for Autosomal Recessive Primary Microcephaly, during Mouse Brain Development.

Centrosomal protein 152 (Cep152) regulates centriole duplication as a molecular scaffold during the cell cycle. Its gene abnormalities are responsible for autosomal recessive primary microcephaly 9 and Seckel syndrome. In this study, we prepared an antibody against mouse Cep152, anti-Cep152, and performed expression analyses focusing on mouse brain development.

Impaired Function of PLEKHG2, a Rho-Guanine Nucleotide-Exchange Factor, Disrupts Corticogenesis in Neurodevelopmental Phenotypes.

Homozygosity of the p.Arg204Trp variation in the Pleckstrin homology and RhoGEF domain containing G2 () gene, which encodes a Rho family-specific guanine nucleotide-exchange factor, is responsible for microcephaly with intellectual disability. However, the role of PLEKHG2 during neurodevelopment remains unknown.