Caenorhabditis elegans Neurotoxicity Testing: Novel Applications in the Adverse Outcome Pathway Framework

Sammi, Shreesh Raj; Jameson, Laura E.; Conrow, Kendra D.; Leung, Maxwell C.K.; Cannon, Jason R.

doi:10.3389/ftox.2022.826488

Cited by 7 publications

(6 citation statements)

References 77 publications

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“…To confirm that the mobility phenotype observed in the fem-1 mutants is due to synaptic defects, we examined the rate of worm paralysis in response to aldicarb and levamisole. Acetylcholine (Ach) is necessary for the transmission of an action potential between neurons, and it exerts its action by binding to nicotinic (nAchR) and muscarinic Ach receptors (Sammi et al, 2022; Spensley et al, 2018). Synaptic acetylcholinesterase (AchE) manages neuromuscular transmission by catabolizing Ach.…”

Section: Resultsmentioning

confidence: 99%

“…1D). However, in the aldicarb assay, a higher percentage of paralyzed worms at a given time indicates a higher general Ach neurotransmission, whereas the levamisole test selectively evaluates nAchR activity (Mahoney et al, 2006; Miller et al, 1996; Sammi et al, 2022). We found that the fem-1 mutants were significantly (p<0.001) more sensitive to aldicarb but not to levamisole (p=0.34) compared to wild-type worms (Fig.…”

Section: Resultsmentioning

confidence: 99%

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A novelde novoFEM1C variant is linked to neurodevelopmental disorder with absent speech, pyramidal signs, and limb ataxia

Dubey

Krygier

Szulc

et al. 2022

Preprint

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Maintaining protein homeostasis (proteostasis) requires the degradation of damaged or unwanted proteins and plays a crucial role in cellular function. The principal proteolytic component of the proteostasis network is the ubiquitin-proteasome system (UPS) which orchestrates protein degradation through ubiquitination of appropriate targets. Ubiquitination is mediated by an enzymatic cascade involving, i.e., E3 ubiquitin ligases, many of which belong to the cullin-RING ligases (CRLs) family. Genetic defects of the UPS are known causes of neurodevelopmental disorders, with >60 entities described so far. Using exome sequencing (ES) to diagnose a pediatric patient with global developmental delay, pyramidal signs, and limb ataxia, we identified a de novo missense variant c.376G>C; p.(Asp126His) in the FEM1C gene, which encodes a CRL substrate receptor. The p.(Asp126His) variant, which alters a conserved amino acid (phyloP100way = 7.9), is located within a highly constrained coding region (CCR=98.6) and is predicted to be pathogenic by the majority (13/19) of in silico tools. To further assess its pathogenicity, we employed Caenorhabditis elegans nematode as a disease model. We found that the mutant vs. wild-type worms had impaired mobility as assessed by track length (p=0.0001), turn counts (p=0.0001), and omega bend counts (p=0.038). Furthermore, mutant worms had histologically normal muscle architecture but were sensitive to an acetylcholinesterase inhibitor - aldicarb which indicates that their locomotion defects result from synaptic defects rather than muscle dysfunction. We conclude that the disease in our patient may be the first reported case of a neurodevelopmental disorder caused by the FEM1C genetic defect.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

A novelde novoFEM1C variant is linked to neurodevelopmental disorder with absent speech, pyramidal signs, and limb ataxia

Dubey

Krygier

Szulc

et al. 2022

Preprint

View full text Add to dashboard Cite

show abstract

“…To confirm that the mobility phenotype observed in the fem-1 mutants is due to synaptic defects, we examined the rate of worm paralysis in response to aldicarb and levamisole. Acetylcholine (Ach) is necessary for the transmission of an action potential between neurons, and it exerts its action by binding to nicotinic (nAchR) and muscarinic Ach receptors ( 32 , 33 ). Synaptic acetylcholinesterase (AchE) manages neuromuscular transmission by catabolizing Ach.…”

Section: Resultsmentioning

confidence: 99%

“…S1D ). However, in the aldicarb assay, a higher percentage of paralyzed worms at a given time indicates a higher general Ach neurotransmission, whereas the levamisole test selectively evaluates nAchR activity ( 33 , 34 , 37 ). We found that the fem-1 mutants were significantly ( P < 0.001) more sensitive to aldicarb but not to levamisole ( P = 0.34) compared to wild-type worms ( Fig.…”

Section: Resultsmentioning

confidence: 99%

A novel de novo FEM1C variant is linked to neurodevelopmental disorder with absent speech, pyramidal signs and limb ataxia

Dubey

Krygier

Szulc

et al. 2022

Human Molecular Genetics

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The principal component of the protein homeostasis network is the ubiquitin-proteasome system. Ubiquitination is mediated by an enzymatic cascade involving, i.e. E3 ubiquitin ligases, many of which belong to the cullin-RING ligases family. Genetic defects in the ubiquitin-proteasome system components, including cullin-RING ligases, are known causes of neurodevelopmental disorders. Using exome sequencing to diagnose a pediatric patient with developmental delay, pyramidal signs, and limb ataxia, we identified a de novo missense variant c.376G > C; p.(Asp126His) in the FEM1C gene encoding a cullin-RING ligase substrate receptor. This variant alters a conserved amino acid located within a highly constrained coding region and is predicted as pathogenic by most in silico tools. In addition, a de novo FEM1C mutation of the same residue p.(Asp126Val) was associated with an undiagnosed developmental disorder, and the relevant variant (FEM1CAsp126Ala) was found to be functionally compromised in vitro. Our computational analysis showed that FEM1CAsp126His hampers protein substrate binding. To further assess its pathogenicity, we used the nematode Caenorhabditis elegans. We found that the FEM-1Asp133His animals (expressing variant homologous to the FEM1C p.(Asp126Val)) had normal muscle architecture yet impaired mobility. Mutant worms were sensitive to the acetylcholinesterase inhibitor aldicarb but not levamisole (acetylcholine receptor agonist), showing that their disabled locomotion is caused by synaptic abnormalities and not muscle dysfunction. In conclusion, we provide the first evidence from an animal model suggesting that a mutation in the evolutionarily conserved FEM1C Asp126 position causes a neurodevelopmental disorder in humans.

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“…High-throughput chemical screening, genetic screening, and behavioral assays can be easily achieved using this model system (Naranjo-Galindo et al 2022 ). A recent study evaluated the morphological and behavioral endpoints of C. elegans in the context of reported AOP of neurodegenerative disorders and demonstrated the homology of human genes and associated proteins in the cholinergic and dopaminergic signaling system (Sammi et al 2022 ). Also, an EFSA study conducted in 2018 showed that this model organism can be used as an alternative tool for ANT and MoA (Masjosthusmann et al 2018 ).…”

Section: Nams and Neurotoxicity Assessmentmentioning

confidence: 99%

Recent advances and current challenges of new approach methodologies in developmental and adult neurotoxicity testing

Serafini,

Sepehri,

Midali

et al. 2024

Arch Toxicol

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Adult neurotoxicity (ANT) and developmental neurotoxicity (DNT) assessments aim to understand the adverse effects and underlying mechanisms of toxicants on the human nervous system. In recent years, there has been an increasing focus on the so-called new approach methodologies (NAMs). The Organization for Economic Co-operation and Development (OECD), together with European and American regulatory agencies, promote the use of validated alternative test systems, but to date, guidelines for regulatory DNT and ANT assessment rely primarily on classical animal testing. Alternative methods include both non-animal approaches and test systems on non-vertebrates (e.g., nematodes) or non-mammals (e.g., fish). Therefore, this review summarizes the recent advances of NAMs focusing on ANT and DNT and highlights the potential and current critical issues for the full implementation of these methods in the future. The status of the DNT in vitro battery (DNT IVB) is also reviewed as a first step of NAMs for the assessment of neurotoxicity in the regulatory context. Critical issues such as (i) the need for test batteries and method integration (from in silico and in vitro to in vivo alternatives, e.g., zebrafish, C. elegans) requiring interdisciplinarity to manage complexity, (ii) interlaboratory transferability, and (iii) the urgent need for method validation are discussed.

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Caenorhabditis elegans Neurotoxicity Testing: Novel Applications in the Adverse Outcome Pathway Framework

Cited by 7 publications

References 77 publications

A novelde novoFEM1C variant is linked to neurodevelopmental disorder with absent speech, pyramidal signs, and limb ataxia

A novelde novoFEM1C variant is linked to neurodevelopmental disorder with absent speech, pyramidal signs, and limb ataxia

A novel de novo FEM1C variant is linked to neurodevelopmental disorder with absent speech, pyramidal signs and limb ataxia

Recent advances and current challenges of new approach methodologies in developmental and adult neurotoxicity testing

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