scholarly journals Interpreting the pathogenicity of Joubert Syndrome missense variants in Caenorhabditis elegans

2020 ◽  
pp. dmm.046631
Author(s):  
Karen I. Lange ◽  
Sofia Tsiropoulou ◽  
Katarzyna Kucharska ◽  
Oliver E. Blacque
Keyword(s):  
Caenorhabditis Elegans ◽  
Primary Cilia ◽  
Model Organism ◽  
Joubert Syndrome ◽  
Compound Heterozygous ◽  
Inherited Disorders ◽  
Missense Variants ◽  
C Elegans ◽  
Variant Alleles ◽  
And Function

Ciliopathies are inherited disorders caused by defects in motile and non-motile (primary) cilia. Ciliopathy syndromes and associated gene variants are often highly pleiotropic and represent exemplars for interrogating genotype-phenotype correlations. Towards understanding disease mechanisms in the context of ciliopathy mutations, we have employed a leading model organism for cilia and ciliopathy research, Caenorhabditis elegans, together with gene editing, to characterise two missense variants (P74S, G155S) in B9D2/mksr-2 associated with Joubert Syndrome (JBTS). B9D2 functions within the Meckel syndrome (MKS) module at the ciliary base transition zone (TZ) compartment, and regulates the cilium's molecular composition and sensory/signaling functions. Quantitative assays of cilium/TZ structure and function, together with knock-in reporters, confirm both variant alleles are pathogenic in worms. G155S causes a more severe overall phenotype and disrupts endogenous MKSR-2 organisation at the TZ. Recapitulation of the patient biallelic genotype shows that compound heterozygous worms phenocopy worms homozygous for P74S. The P74S and G155S alleles also reveal evidence of a very close functional association between the B9D2-associated B9 complex and TMEM216/MKS-2. Together, these data establish C. elegans as a paradigm for interpreting JBTS mutations, and provide further insight into MKS module organisation.

scholarly journals Interpreting the pathogenicity of Joubert Syndrome missense variants in Caenorhabditis elegans

2020 ◽  
Author(s):  
Karen I. Lange ◽  
Sofia Tsiropoulou ◽  
Katarzyna Kucharska ◽  
Oliver E. Blacque
Keyword(s):  
Caenorhabditis Elegans ◽  
Joubert Syndrome ◽  
Phenotype Correlation ◽  
Inherited Disorders ◽  
Missense Variants ◽  
C Elegans ◽  
Signaling Function ◽  
Variant Alleles ◽  
And Function ◽  
Insight Into

ABSTRACTCiliopathies are inherited disorders caused by cilia defects. Variants in ciliopathy genes are frequently pleiotropic and represent excellent case studies for interrogating genotype-phenotype correlation. We have employed Caenorhabditis elegans and gene editing to characterise two pathogenic biallelic missense variants (P74S, G155S) in B9D2/mksr-2 associated with Joubert Syndrome (JBTS). B9D2 functions within the MKS module at the transition zone (TZ) ciliary subcompartment, and regulates the cilium’s molecular composition and signaling function. Quantitative assays of cilium/TZ structure and function, together with knock-in reporters, confirm both variant alleles are pathogenic. G155S causes a more severe overall phenotype and disrupts endogenous MKSR-2 organisation at the TZ. Recapitulation of the patient biallelic genotype shows that heterozygous worms phenocopy worms homozygous for P74S. This study also reveals a close functional association between the B9 complex and TMEM216/MKS-2. These data establish C. elegans as a paradigm for interpreting JBTS mutations, and provide insight into MKS module organisation.

scholarly journals Functional Redundancy of the B9 Proteins and Nephrocystins in Caenorhabditis elegans Ciliogenesis

2008 ◽  
Vol 19 (5) ◽  
pp. 2154-2168 ◽  
Author(s):  
Corey L. Williams ◽  
Marlene E. Winkelbauer ◽  
Jenny C. Schafer ◽  
Edward J. Michaud ◽  
Bradley K. Yoder
Keyword(s):  
Caenorhabditis Elegans ◽  
Joubert Syndrome ◽  
Cystic Kidney ◽  
Basal Bodies ◽  
The Novel ◽  
C Elegans ◽  
Human Genes ◽  
Cilia Formation ◽  
Strong Candidate ◽  
Candidate Loci

Meckel-Gruber syndrome (MKS), nephronophthisis (NPHP), and Joubert syndrome (JBTS) are a group of heterogeneous cystic kidney disorders with partially overlapping loci. Many of the proteins associated with these diseases interact and localize to cilia and/or basal bodies. One of these proteins is MKS1, which is disrupted in some MKS patients and contains a B9 motif of unknown function that is found in two other mammalian proteins, B9D2 and B9D1. Caenorhabditis elegans also has three B9 proteins: XBX-7 (MKS1), TZA-1 (B9D2), and TZA-2 (B9D1). Herein, we report that the C. elegans B9 proteins form a complex that localizes to the base of cilia. Mutations in the B9 genes do not overtly affect cilia formation unless they are in combination with a mutation in nph-1 or nph-4, the homologues of human genes (NPHP1 and NPHP4, respectively) that are mutated in some NPHP patients. Our data indicate that the B9 proteins function redundantly with the nephrocystins to regulate the formation and/or maintenance of cilia and dendrites in the amphid and phasmid ciliated sensory neurons. Together, these data suggest that the human homologues of the novel B9 genes B9D2 and B9D1 will be strong candidate loci for pathologies in human MKS, NPHP, and JBTS.

Behavioral Effects of Volatile Anesthetics in Caenorhabditis elegans

1996 ◽  
Vol 85 (4) ◽  
pp. 901-912 ◽  
Author(s):  
Michael C. Crowder ◽  
Laynie D. Shebester ◽  
Tim Schedl
Keyword(s):  
Nervous System ◽  
Caenorhabditis Elegans ◽  
Time Course ◽  
Model Organism ◽  
Volatile Anesthetic ◽  
Volatile Anesthetics ◽  
Effective Concentration ◽  
Forward Genetics ◽  
C Elegans ◽  
Median Effective Concentration

Background The nematode Caenorhabditis elegans offers many advantages as a model organism for studying volatile anesthetic actions. It has a simple, well-understood nervous system; it allows the researcher to do forward genetics; and its genome will soon be completely sequenced. C. elegans is immobilized by volatile anesthetics only at high concentrations and with an unusually slow time course. Here other behavioral dysfunctions are considered as anesthetic endpoints in C. elegans. Methods The potency of halothane for disrupting eight different behaviors was determined by logistic regression of concentration and response data. Other volatile anesthetics were also tested for some behaviors. Established protocols were used for behavioral endpoints that, except for pharyngeal pumping, were set as complete disruption of the behavior. Time courses were measured for rapid behaviors. Recovery from exposure to 1 or 4 vol% halothane was determined for mating, chemotaxis, and gross movement. All experiments were performed at 20 to 22 degrees C. Results The median effective concentration values for halothane inhibition of mating (0.30 vol%-0.21 mM), chemotaxis (0.34 vol%-0.24 mM), and coordinated movement (0.32 vol% - 0.23 mM) were similar to the human minimum alveolar concentration (MAC; 0.21 mM). In contrast, halothane produced immobility with a median effective concentration of 3.65 vol% (2.6 mM). Other behaviors had intermediate sensitivities. Halothane's effects reached steady-state in 10 min for all behaviors tested except immobility, which required 2 h. Recovery was complete after exposure to 1 vol% halothane but was significantly reduced after exposure to immobilizing concentrations. Conclusions Volatile anesthetics selectively disrupt C. elegans behavior. The potency, time course, and recovery characteristics of halothane's effects on three behaviors are similar to its anesthetic properties in vertebrates. The affected nervous system molecules may express structural motifs similar to those on vertebrate anesthetic targets.

scholarly journals Stochastic left–right neuronal asymmetry in Caenorhabditis elegans

2016 ◽  
Vol 371 (1710) ◽  
pp. 20150407 ◽  
Author(s):  
Amel Alqadah ◽  
Yi-Wen Hsieh ◽  
Rui Xiong ◽  
Chiou-Fen Chuang
Keyword(s):  
Caenorhabditis Elegans ◽  
Molecular Mechanisms ◽  
Neurological Diseases ◽  
Calcium Signalling ◽  
Model Organism ◽  
Brain Asymmetry ◽  
C Elegans ◽  
Left And Right ◽  
Left Right Asymmetry ◽  
Neuronal Asymmetry

Left–right asymmetry in the nervous system is observed across species. Defects in left–right cerebral asymmetry are linked to several neurological diseases, but the molecular mechanisms underlying brain asymmetry in vertebrates are still not very well understood. The Caenorhabditis elegans left and right amphid wing ‘C’ (AWC) olfactory neurons communicate through intercellular calcium signalling in a transient embryonic gap junction neural network to specify two asymmetric subtypes, AWC OFF (default) and AWC ON (induced), in a stochastic manner. Here, we highlight the molecular mechanisms that establish and maintain stochastic AWC asymmetry. As the components of the AWC asymmetry pathway are highly conserved, insights from the model organism C. elegans may provide a window onto how brain asymmetry develops in humans. This article is part of the themed issue ‘Provocative questions in left–right asymmetry’.

scholarly journals An Evolutionarily Conserved Pathway Essential for Orsay Virus Infection of Caenorhabditis elegans

mBio ◽  
2017 ◽  
Vol 8 (5) ◽  
Author(s):  
Hongbing Jiang ◽  
Kevin Chen ◽  
Luis E. Sandoval ◽  
Christian Leung ◽  
David Wang
Keyword(s):  
Caenorhabditis Elegans ◽  
Virus Infection ◽  
Tyrosine Kinase ◽  
Model Organism ◽  
Wiskott Aldrich Syndrome ◽  
C Elegans ◽  
Evolutionarily Conserved ◽  
Conserved Genes ◽  
Orsay Virus ◽  
Syndrome Protein

ABSTRACT Many fundamental biological discoveries have been made in Caenorhabditis elegans. The discovery of Orsay virus has enabled studies of host-virus interactions in this model organism. To identify host factors critical for Orsay virus infection, we designed a forward genetic screen that utilizes a virally induced green fluorescent protein (GFP) reporter. Following chemical mutagenesis, two Viro (virus induced reporter off) mutants that failed to express GFP were mapped to sid-3, a nonreceptor tyrosine kinase, and B0280.13 (renamed viro-2), an ortholog of human Wiskott-Aldrich syndrome protein (WASP). Both mutants yielded Orsay virus RNA levels comparable to that of the residual input virus, suggesting that they are not permissive for Orsay virus replication. In addition, we demonstrated that both genes affect an early prereplication stage of Orsay virus infection. Furthermore, it is known that the human ortholog of SID-3, activated CDC42-associated kinase (ACK1/TNK2), is capable of phosphorylating human WASP, suggesting that VIRO-2 may be a substrate for SID-3 in C. elegans. A targeted RNA interference (RNAi) knockdown screen further identified the C. elegans gene nck-1, which has a human ortholog that interacts with TNK2 and WASP, as required for Orsay virus infection. Thus, genetic screening in C. elegans identified critical roles in virus infection for evolutionarily conserved genes in a known human pathway. IMPORTANCE Orsay virus is the only known virus capable of naturally infecting the model organism Caenorhabditis elegans, which shares many evolutionarily conserved genes with humans. We exploited the robust genetic tractability of C. elegans to identify three host genes, sid-3, viro-2, and nck-1, which are essential for Orsay virus infection. Mutant animals that lack these three genes are highly defective in viral replication. Strikingly, the human orthologs of these three genes, activated CDC42-associated kinase (TNK2), Wiskott-Aldrich syndrome protein (WASP), and noncatalytic region of tyrosine kinase adaptor protein 1 (NCK1) are part of a known signaling pathway in mammals. These results suggest that TNK2, WASP, and NCK1 may play important roles in mammalian virus infection. IMPORTANCE Orsay virus is the only known virus capable of naturally infecting the model organism Caenorhabditis elegans, which shares many evolutionarily conserved genes with humans. We exploited the robust genetic tractability of C. elegans to identify three host genes, sid-3, viro-2, and nck-1, which are essential for Orsay virus infection. Mutant animals that lack these three genes are highly defective in viral replication. Strikingly, the human orthologs of these three genes, activated CDC42-associated kinase (TNK2), Wiskott-Aldrich syndrome protein (WASP), and noncatalytic region of tyrosine kinase adaptor protein 1 (NCK1) are part of a known signaling pathway in mammals. These results suggest that TNK2, WASP, and NCK1 may play important roles in mammalian virus infection.

scholarly journals Neuroligin dependence of social behaviour in Caenorhabditis elegans provides a model to investigate an autism-associated gene

2020 ◽  
Author(s):  
Helena Rawsthorne ◽  
Fernando Calahorro ◽  
Emily Feist ◽  
Lindy Holden-Dye ◽  
Vincent O’Connor ◽  
...  
Keyword(s):  
Caenorhabditis Elegans ◽  
Genetic Variants ◽  
Social Behaviour ◽  
Animal Studies ◽  
Model Organism ◽  
Autism Spectrum ◽  
C Elegans ◽  
Important Regulator ◽  
Human Mutation ◽  
The Impact

Abstract Autism spectrum disorder (ASD) is characterized by a triad of behavioural impairments including social behaviour. Neuroligin, a trans-synaptic adhesion molecule, has emerged as a penetrant genetic determinant of behavioural traits that signature the neuroatypical behaviours of autism. However, the function of neuroligin in social circuitry and the impact of genetic variation to this gene is not fully understood. Indeed, in animal studies designed to model autism, there remains controversy regarding the role of neuroligin dysfunction in the expression of disrupted social behaviours. The model organism, Caenorhabditis elegans, offers an informative experimental platform to investigate the impact of genetic variants on social behaviour. In a number of paradigms, it has been shown that inter-organismal communication by chemical cues regulates C. elegans social behaviour. We utilize this social behaviour to investigate the effect of autism-associated genetic variants within the social domain of the research domain criteria. We have identified neuroligin as an important regulator of social behaviour and segregate the importance of this gene to the recognition and/or processing of social cues. We also use CRISPR/Cas9 to edit an R-C mutation that mimics a highly penetrant human mutation associated with autism. C. elegans carrying this mutation phenocopy the behavioural dysfunction of a C. elegans neuroligin null mutant, thus confirming its significance in the regulation of animal social biology. This highlights that quantitative behaviour and precision genetic intervention can be used to manipulate discrete social circuits of the worm to provide further insight into complex social behaviour.

scholarly journals Caenorhabditis elegans as a Model Organism to Evaluate the Antioxidant Effects of Phytochemicals

Molecules ◽  
2020 ◽  
Vol 25 (14) ◽  
pp. 3194
Author(s):  
Begoña Ayuda-Durán ◽  
Susana González-Manzano ◽  
Ana M. González-Paramás ◽  
Celestino Santos-Buelga
Keyword(s):  
Oxidative Stress ◽  
Caenorhabditis Elegans ◽  
Model Organism ◽  
Lipid Peroxides ◽  
Biological Research ◽  
Loss Of Function ◽  
Fluorescent Reporters ◽  
C Elegans ◽  
High Degree

The nematode Caenorhabditis elegans was introduced as a model organism in biological research by Sydney Brenner in the 1970s. Since then, it has been increasingly used for investigating processes such as ageing, oxidative stress, neurodegeneration, or inflammation, for which there is a high degree of homology between C. elegans and human pathways, so that the worm offers promising possibilities to study mechanisms of action and effects of phytochemicals of foods and plants. In this paper, the genes and pathways regulating oxidative stress in C. elegans are discussed, as well as the methodological approaches used for their evaluation in the worm. In particular, the following aspects are reviewed: the use of stress assays, determination of chemical and biochemical markers (e.g., ROS, carbonylated proteins, lipid peroxides or altered DNA), influence on gene expression and the employment of mutant worm strains, either carrying loss-of-function mutations or fluorescent reporters, such as the GFP.

scholarly journals Caenorhabditis elegans as an Emerging Model for Virus-Host Interactions

2017 ◽  
Vol 91 (23) ◽  
Author(s):  
Don B. Gammon
Keyword(s):  
Caenorhabditis Elegans ◽  
Virus Infection ◽  
Fungal Pathogens ◽  
Model Organism ◽  
Artificial Infection ◽  
Viral Pathogen ◽  
Content Type ◽  
Host Interactions ◽  
C Elegans ◽  
Infection Models

ABSTRACT Since 1999, Caenorhabditis elegans has been extensively used to study microbe-host interactions due to its simple culture, genetic tractability, and susceptibility to numerous bacterial and fungal pathogens. In contrast, virus studies have been hampered by a lack of convenient virus infection models in nematodes. The recent discovery of a natural viral pathogen of C. elegans and development of diverse artificial infection models are providing new opportunities to explore virus-host interplay in this powerful model organism.

scholarly journals Hydrogen Peroxide-Mediated Killing of Caenorhabditis elegans by Streptococcus pyogenes

2002 ◽  
Vol 70 (9) ◽  
pp. 5202-5207 ◽  
Author(s):  
W. T. M. Jansen ◽  
M. Bolm ◽  
R. Balling ◽  
G. S. Chhatwal ◽  
R. Schnabel
Keyword(s):  
Hydrogen Peroxide ◽  
Caenorhabditis Elegans ◽  
Streptococcus Pyogenes ◽  
Wide Spectrum ◽  
Model Organism ◽  
Common Mechanism ◽  
Gram Positive ◽  
C Elegans ◽  
Gram Positive Bacteria ◽  
Serovar Typhimurium

ABSTRACT Caenorhabditis elegans is currently introduced as a new, facile, and cheap model organism to study the pathogenesis of gram-negative bacteria such as Pseudomonas aeruginosa and Salmonella enterica serovar Typhimurium. The mechanisms of killing involve either diffusible exotoxins or infection-like processes. Recently, it was shown that also some gram-positive bacteria kill C. elegans, although the precise mechanisms of killing remained open. We examined C. elegans as a pathogenesis model for the gram-positive bacterium Streptococcus pyogenes, a major human pathogen capable of causing a wide spectrum of diseases. We demonstrate that S. pyogenes kills C. elegans, both on solid and in liquid medium. Unlike P. aeruginosa and S. enterica serovar Typhimurium, the killing by S. pyogenes is solely mediated by hydrogen peroxide. Killing required live streptococci; the killing capacity depends on the amount of hydrogen peroxide produced, and killing can be inhibited by catalase. Major exotoxins of S. pyogenes are not involved in the killing process as confirmed by using specific toxin inhibitors and knockout mutants. Moreover, no accumulation of S. pyogenes in C. elegans is observed, which excludes the involvement of infection-like processes. Preliminary results show that S. pneumoniae can also kill C. elegans by hydrogen peroxide production. Hydrogen peroxide-mediated killing might represent a common mechanism by which gram-positive, catalase-negative pathogens kill C. elegans.

scholarly journals The Caenorhabditis elegans muscle-affecting gene unc-87 encodes a novel thin filament-associated protein.

1994 ◽  
Vol 127 (1) ◽  
pp. 79-93 ◽  
Author(s):  
S Goetinck ◽  
R H Waterston
Keyword(s):  
Caenorhabditis Elegans ◽  
Gene Product ◽  
Thin Filament ◽  
Genomic Sequence ◽  
Muscle Protein ◽  
Thin Filaments ◽  
C Elegans ◽  
Neuronal Protein ◽  
And Function ◽  
Filament Protein

Mutations in the unc-87 gene of Caenorhabditis elegans affect the structure and function of bodywall muscle, resulting in variable paralysis. We cloned the unc-87 gene by taking advantage of a transposon-induced allele of unc-87 and the correspondence of the genetic and physical maps in C. elegans. A genomic clone was isolated that alleviates the mutant phenotype when introduced into unc-87 mutants. Sequence analysis of a corresponding cDNA clone predicts a 357-amino acid, 40-kD protein that is similar to portions of the vertebrate smooth muscle proteins calponin and SM22 alpha, the Drosophila muscle protein mp20, the deduced product of the C. elegans cDNA cm7g3, and the rat neuronal protein np25. Analysis of the genomic sequence and of various transcripts represented in a cDNA library suggest that unc-87 mRNAs are subject to alternative splicing. Immunohistochemistry of wildtype and mutant animals with antibodies to an unc-87 fusion protein indicates that the gene product is localized to the I-band of bodywall muscle. Studies of the UNC-87 protein in other muscle mutants suggest that the unc-87 gene product associates with thin filaments, in a manner that does not depend on the presence of the thin filament protein tropomyosin.

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