scholarly journals Impaired OTUD7A-dependent Ankyrin regulation mediates neuronal dysfunction in mouse and human models of the 15q13.3 microdeletion syndrome

2022 ◽  
Author(s):  
Brianna K Unda ◽  
Leon Chalil ◽  
Sehyoun Yoon ◽  
Savannah Kilpatrick ◽  
Sansi Xing ◽  
...  
Keyword(s):  
Copy Number Variations ◽  
Cytoskeletal Proteins ◽  
Network Activity ◽  
Neuronal Dysfunction ◽  
Structured Illumination Microscopy ◽  
Microdeletion Syndrome ◽  
Developmental Defects ◽  
Risk Genes ◽  
Ankyrin G ◽  
Disease Mechanisms

Copy number variations (CNV) are associated with psychiatric and neurodevelopmental disorders (NDDs), and most, including the recurrent 15q13.3 microdeletion disorder, have unknown disease mechanisms. We used a heterozygous 15q13.3 microdeletion mouse model and patient iPSC-derived neurons to reveal developmental defects in neuronal maturation and network activity. To identify the underlying molecular dysfunction, we developed a neuron-specific proximity-labeling proteomics (BioID2) pipeline, combined with patient mutations, to target the 15q13.3 CNV genetic driver OTUD7A. OTUD7A is an emerging independent NDD risk gene with no known function in the brain, but has putative deubiquitinase (DUB) function. The OTUD7A protein-protein interaction (PPI) network revealed interactions with synaptic, axonal, and cytoskeletal proteins and was enriched for known ASD and epilepsy risk genes. The interactions between OTUD7A and the NDD risk genes Ankyrin-G (Ank3) and Ankyrin-B (Ank2) were disrupted by an epilepsy-associated OTUD7A L233F variant. Further investigation of Ankyrin-G in mouse and human 15q13.3 microdeletion and OTUD7AL233F/L233F models revealed protein instability, increased polyubiquitination, and decreased levels in the axon initial segment (AIS), while structured illumination microscopy identified reduced Ankyrin-G nanodomains in dendritic spines. Functional analysis of human 15q13.3 microdeletion and OTUD7AL233F/L233F models revealed shared and distinct impairments to axonal growth and intrinsic excitability. Importantly, restoring OTUD7A or Ankyrin-G expression in 15q13.3 microdeletion neurons led to a reversal of abnormalities. These data reveal a critical OTUD7A-Ankyrin pathway in neuronal development, which is impaired in the 15q13.3 microdeletion syndrome, leading to neuronal dysfunction. Further, our study highlights the utility of targeting CNV genes using cell-type specific proteomics to identify shared and unexplored disease mechanisms across NDDs.

scholarly journals Identification and validation of novel candidate risk genes in endocytic vesicular trafficking associated with esophageal atresia and tracheoesophageal fistulas

2021 ◽  
Author(s):  
Guojie Zhong ◽  
Priyanka Ahimaz ◽  
Nicole A. Edwards ◽  
Jacob J. Hagen ◽  
Christophe Faure ◽  
...  
Keyword(s):  
Genetic Variants ◽  
Congenital Anomalies ◽  
De Novo ◽  
Simulation Analysis ◽  
Loss Of Function ◽  
Developmental Defects ◽  
Risk Genes ◽  
Significant Burden ◽  
Background Mutation Rate ◽  
Complex Cases

Esophageal atresias/tracheoesophageal fistulas (EA/TEF) are rare congenital anomalies caused by aberrant development of the foregut. Previous studies indicate that rare or de novo genetic variants significantly contribute to EA/TEF risk, and most individuals with EA/TEF do not have pathogenic genetic variants in established risk genes. To identify novel genetic contributions to EA/TEF, we performed whole genome sequencing of 185 trios (probands and parents) with EA/TEF, including 59 isolated and 126 complex cases with additional congenital anomalies and/or neurodevelopmental disorders. There was a significant burden of protein altering de novo coding variants in complex cases (p=3.3e-4), especially in genes that are intolerant of loss of function variants in the population. We performed simulation analysis of pathway enrichment based on background mutation rate and identified a number of pathways related to endocytosis and intracellular trafficking that as a group have a significant burden of protein altering de novo variants. We assessed 18 variants for disease causality using CRISPR-Cas9 mutagenesis in Xenopus and confirmed 13 with tracheoesophageal phenotypes. Our results implicate disruption of endosome-mediated epithelial remodeling as a potential mechanism of foregut developmental defects. This research may have implications for the mechanisms of other rare congenital anomalies.

scholarly journals A Case With 4 de Novo Copy Number Variations With Clinical Features That Overlap 1q43q44 Microdeletion and 3q29 Microduplication Syndromes

2018 ◽  
Vol 5 ◽  
pp. 2329048X1879820
Author(s):  
Miriam Kessi ◽  
Jing Peng ◽  
Lifen Yang ◽  
Haolin Duan ◽  
Yulin Tang ◽  
...  
Keyword(s):  
Intellectual Disability ◽  
Corpus Callosum ◽  
Copy Number ◽  
De Novo ◽  
Copy Number Variations ◽  
Language Delay ◽  
Global Developmental Delay ◽  
Recurrent Infections ◽  
Dental Anomalies ◽  
Microdeletion Syndrome

1q43q44 microdeletion syndrome is characterized by intellectual disability/global developmental delay, epilepsy, dysmorphic facies, stereotypic movement, language delay, recurrent infections, dental anomalies, and hand and foot anomalies. Microcephaly and corpus callosum dysplasia are present in some cases depending on gene content. 3q29 microduplication syndrome is characterized by intellectual disability, language delay, microcephaly, and dental anomalies. We report the first case with 4 de novo copy number variations with clinical features which overlap 1q43q44 microdeletion and 3q29 microduplication syndromes. Our case presented with global developmental delay, epilepsy, recurrent infections, stereotypic movements, speech delay, microcephaly, facial dysmorphism, bilateral clinodactyly, and small puffy feet with metatarsus varus; however, she had no corpus callosum dysplasia. Our case highlights the role of multiple copy number variations in the occurrence of a certain phenotype. Moreover, it supports the theory that the loss of HNRNPU gene function cannot explain the occurrence of microcephaly and abnormalities of the corpus callosum in 1q43q44 microdeletion syndrome.

scholarly journals Nodes of Ranvier and axon initial segments are ankyrin G–dependent domains that assemble by distinct mechanisms

2007 ◽  
Vol 177 (5) ◽  
pp. 857-870 ◽  
Author(s):  
Yulia Dzhashiashvili ◽  
Yanqing Zhang ◽  
Jolanta Galinska ◽  
Isabel Lam ◽  
Martin Grumet ◽  
...  
Keyword(s):  
Schwann Cells ◽  
Sodium Channels ◽  
Cytoskeletal Proteins ◽  
Action Potential Generation ◽  
Potential Generation ◽  
Nodes Of Ranvier ◽  
Ankyrin G ◽  
Sites Of Action ◽  
Axon Initial Segments ◽  
Inside Out

Axon initial segments (AISs) and nodes of Ranvier are sites of action potential generation and propagation, respectively. Both domains are enriched in sodium channels complexed with adhesion molecules (neurofascin [NF] 186 and NrCAM) and cytoskeletal proteins (ankyrin G and βIV spectrin). We show that the AIS and peripheral nervous system (PNS) nodes both require ankyrin G but assemble by distinct mechanisms. The AIS is intrinsically specified; it forms independent of NF186, which is targeted to this site via intracellular interactions that require ankyrin G. In contrast, NF186 is targeted to the node, and independently cleared from the internode, by interactions of its ectodomain with myelinating Schwann cells. NF186 is critical for and initiates PNS node assembly by recruiting ankyrin G, which is required for the localization of sodium channels and the entire nodal complex. Thus, initial segments assemble from the inside out driven by the intrinsic accumulation of ankyrin G, whereas PNS nodes assemble from the outside in, specified by Schwann cells, which direct the NF186-dependent recruitment of ankyrin G.

scholarly journals 16p11.2 deletion is associated with hyperactivation of human iPSC-derived dopaminergic neuron networks and is rescued by RHOA inhibition in vitro

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Maria Sundberg ◽  
Hannah Pinson ◽  
Richard S. Smith ◽  
Kellen D. Winden ◽  
Pooja Venugopal ◽  
...  
Keyword(s):  
Pluripotent Stem Cells ◽  
Wide Spectrum ◽  
Copy Number Variations ◽  
Network Activity ◽  
Neuron Networks ◽  
Soma Size ◽  
Marker Expression ◽  
Induced Pluripotent ◽  
Human Ipsc

AbstractReciprocal copy number variations (CNVs) of 16p11.2 are associated with a wide spectrum of neuropsychiatric and neurodevelopmental disorders. Here, we use human induced pluripotent stem cells (iPSCs)-derived dopaminergic (DA) neurons carrying CNVs of 16p11.2 duplication (16pdup) and 16p11.2 deletion (16pdel), engineered using CRISPR-Cas9. We show that 16pdel iPSC-derived DA neurons have increased soma size and synaptic marker expression compared to isogenic control lines, while 16pdup iPSC-derived DA neurons show deficits in neuronal differentiation and reduced synaptic marker expression. The 16pdel iPSC-derived DA neurons have impaired neurophysiological properties. The 16pdel iPSC-derived DA neuronal networks are hyperactive and have increased bursting in culture compared to controls. We also show that the expression of RHOA is increased in the 16pdel iPSC-derived DA neurons and that treatment with a specific RHOA-inhibitor, Rhosin, rescues the network activity of the 16pdel iPSC-derived DA neurons. Our data suggest that 16p11.2 deletion-associated iPSC-derived DA neuron hyperactivation can be rescued by RHOA inhibition.

scholarly journals Meiosis-Specific Cohesin Complexes Display Distinct and Essential Roles in Mitotic ESC Chromosomes

2021 ◽  
Author(s):  
Eui-Hwan Choi ◽  
Young Eun Koh ◽  
Seobin Yoon ◽  
Yoonsoo Hahn ◽  
Keun P Kim
Keyword(s):  
Embryonic Stem ◽  
Dependent Manner ◽  
Structured Illumination ◽  
Loss Of Function ◽  
Structured Illumination Microscopy ◽  
Developmental Defects ◽  
Chromatid Cohesion ◽  
Functional Analyses ◽  
Stalled Replication Forks ◽  
Mitosis And Meiosis

Cohesin is a chromosome-associated SMC-kleisin complex that mediates sister chromatid cohesion, recombination, and most chromosomal processes during mitosis and meiosis. Through high-resolution 3D-structured illumination microscopy and functional analyses, we report multiple biological processes associated with the meiosis-specific cohesin components, REC8 and STAG3, and the distinct loss of function of meiotic cohesin during the cell cycle of embryonic stem cells (ESCs). First, we show that REC8 is translocated into the nucleus in a STAG3-dependent manner. REC8/STAG3-containing cohesin regulates chromosome topological properties and specifically maintains centromeric cohesion. Second, REC8 and mitotic cohesin RAD21 are located at adjacent sites but predominantly at nonoverlapping sites on ESC chromosomes, implying that REC8 can function independent of RAD21 in ESCs. Third, knockdown of REC8-cohesin not only leads to higher rates of premature centromere separation and stalled replication forks, which can cause proliferation and developmental defects, but also enhances compaction of the chromosome structure by hyperloading of retinoblastoma protein-condensin complexes from prophase onward. We propose that the delicate balance between mitotic and meiotic cohesins may regulate ESC-specific chromosomal organization and mitotic program.

Fooling Mother Nature: Epigenetics and Novel Treatments for Psychiatric Disorders

CNS Spectrums ◽  
2010 ◽  
Vol 15 (6) ◽  
pp. 358-366 ◽  
Author(s):  
Stephen M. Stahl
Keyword(s):  
Psychiatric Disorders ◽  
Genetic Disease ◽  
Gene Products ◽  
Risk Genes ◽  
Mother Nature ◽  
Novel Treatments ◽  
Brain Circuits ◽  
Disease Mechanisms ◽  
Normal Gene ◽  
Altered Gene

Modern formulations of psychiatric disorders hypothesize that mother nature goes awry, causing both genetic and epigenetic disease actions. Genetic disease actions are the consequences of naturally inherited risk genes that have an altered sequence of DNA. This altered DNA sequence theoretically leads to the production of altered gene products in neurons, causing inefficient information processing in various brain circuits, and biasing those circuits towards developing symptoms of a mental illness. Epigenetic disease actions are theorized either to activate risk genes to make an altered gene product or to activate normal genes to make normal gene products but at the wrong time. Epigenetic disease mechanisms theoretically turn normal genes into risk genes by causing normal genes to be expressed in neurons when these genes should be silenced or by causing normal genes to be silenced when they should be expressed.

Molecular genetics and biology of dementia

2013 ◽  
Author(s):  
Denise Harold ◽  
Julie Williams
Keyword(s):  
Association Studies ◽  
Genetic Research ◽  
Genome Wide Association ◽  
Genetic Mutations ◽  
Genome Wide Association Studies ◽  
Risk Genes ◽  
The Past ◽  
Disease Mechanisms ◽  
Genome Wide ◽  
Made In

Considerable progress has been made in our understanding of the genetics and molecular biology of dementia. In this chapter we focus predominantly on the most common form of dementia, Alzheimer’s disease (AD), but also discuss vascular dementia and frontotemporal dementia. Genetic mutations have been identified that cause Mendelian subtypes of each disorder, and in recent years genome-wide association studies have greatly aided the identification of risk genes for more common forms of disease. For example, 9 susceptibility genes have been identified in AD in the past 3 years as a result of genome-wide association studies, the first robust risk loci to be identified since APOE in 1993. This progress in genetic research is having a dramatic effect on our understanding of disease pathogenesis, by refining previous ideas and defining new primary disease mechanisms.

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