Gαq Mediates Clozapine Effects in Caenorhabditis elegans

ABSTRACTClozapine binds and has significant effects on multiple neurotransmitter receptors, notably including some dopamine receptors. Downstream of these receptors, clozapine affects the balance of Gi− and Gq-dependent second-messenger signaling. We used Caenorhabiditis elegans as a genetic model to study further how clozapine affects both dopamine receptors and downstream Gq mediated signaling. Four of six worm dopamine receptor orthologs, dop-1, dop-2, dop-4, and dop-5 produced resistance to clozapine induced developmental delay when mutated, suggesting that both type I and type II dopamine receptors mediate the behavioral effects of clozapine in C. elegans. Beyond these receptors, reduction of function of one of the G proteins, egl-30 (Gαq), produced greatly increased susceptibility to clozapine. Gαq has multiple known downstream effects. Among these is the control of acetylcholine release, which is in balance with monoamines in the human brain and is another target of clozapine and other antipsychotic drugs. We tested for downstream effects on acetylcholine at the neuromuscular junction upon clozapine treatment but found no evidence for effects of clozapine. In contrast, modulation of Gαq upstream leads to worms that are either more resistant or more susceptible to clozapine, emphasizing the importance of Gαq proteins in mediating effects of clozapine. A genetic screen for suppressors of egl-30 recovered eight mutants. By characterizing the behavioral effects of these mutants, we found that clozapine exerts its function on development by affecting Gαq signaling through control of the pharyngeal pumping rate. A whole-genome sequencing technique was utilized and identified a list of candidate genes for these suppressor mutations. Further characterization of these mutants promises the discovery of novel components participating in Gαq signaling and a better understanding of the mechanisms of action of clozapine.

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Enhanced Healthspan in Caenorhabditis elegans Treated With Extracts From the Traditional Chinese Medicine Plants Cuscuta chinensis Lam. and Eucommia ulmoides Oliv.

Frontiers in Pharmacology ◽

10.3389/fphar.2021.604435 ◽

2021 ◽

Vol 12 ◽

Author(s):

Shimaa M. A. Sayed ◽

Karsten Siems ◽

Christian Schmitz-Linneweber ◽

Walter Luyten ◽

Nadine Saul

Keyword(s):

Caenorhabditis Elegans ◽

Chinese Medicine ◽

Traditional Chinese Medicine ◽

Eucommia Ulmoides ◽

Pumping Rate ◽

C Elegans ◽

Beneficial Effects ◽

Physiological Fitness ◽

Pharyngeal Pumping ◽

Cuscuta Chinensis

To uncover potential anti-aging capacities of Traditional Chinese Medicine (TCM), the nematode Caenorhabditis elegans was used to investigate the effects of Eucommia ulmoides and Cuscuta chinensis extracts, selected by screening seven TCM extracts, on different healthspan parameters. Nematodes exposed to E. ulmoides and C. chinensis extracts, starting at the young adult stage, exhibited prolonged lifespan and increased survival after heat stress as well as upon exposure to the pathogenic bacterium Photorhabdus luminescens, whereby the survival benefits were monitored after stress initiation at different adult stages. However, only C. chinensis had the ability to enhance physical fitness: the swimming behavior and the pharyngeal pumping rate of C. elegans were improved at day 7 and especially at day 12 of adulthood. Finally, monitoring the red fluorescence of aged worms revealed that only C. chinensis extracts caused suppression of intestinal autofluorescence, a known marker of aging. The results underline the different modes of action of the tested plants extracts. E. ulmoides improved specifically the physiological fitness by increasing the survival probability of C. elegans after stress, while C. chinensis seems to be an overall healthspan enhancer, reflected in the suppressed autofluorescence, with beneficial effects on physical as well as physiological fitness. The C. chinensis effects may be hormetic: this is supported by increased gene expression of hsp-16.1 and by trend, also of hsp-12.6.

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Some Phenotypic Characteristics of Nematode Caenorhabditis elegans Strains with Defective Functions of the Sestrin (cSesn) gene

Biomedical & Pharmacology Journal ◽

10.13005/bpj/1430 ◽

2018 ◽

Vol 11 (2) ◽

pp. 759-767 ◽

Cited By ~ 3

Author(s):

A. O. Zeltukhin ◽

G. V. Ilyinskaya ◽

A. V. Budanov ◽

P. M. Chumakov

Keyword(s):

Caenorhabditis Elegans ◽

Redox Homeostasis ◽

Functional Decline ◽

Extended Period ◽

Locomotory Activity ◽

Pumping Rate ◽

Phenotypic Differences ◽

C Elegans ◽

Age Related ◽

Pharyngeal Pumping

In mammals a small family of genes called Sestrins play important roles in the maintenance of metabolic and redox homeostasis, suggesting that the genes may positively affect the lifespan and counteract the age-related functional decline. The nematode genome contains a single cSesn gene that makes the Caenorhabditis elegans an excellent model for studying functions of the sestrin family. We describe phenotypic differences of worms that have compromised expression of cSesn gene. By comparing three different cSesn-deficient modes with the wild-type C. elegans strain we show that the abrogation of cSesn expression results in an increased body size, an extended period of body growth, a reduces brood size and number of offspring per a single worm, an accelerated decline in muscular functions revealed as a rapid decrease in the pharyngeal pumping rate and in the overall locomotory activity. The results are consistent with the potential roles of cSesn in counteracting the process of aging in C. elegans.

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Pharyngeal timing and particle transport defects in Caenorhabditis elegans feeding mutants

10.1101/2021.09.30.462635 ◽

2021 ◽

Author(s):

Isaac Ravi Brenner ◽

David M. Raizen ◽

Christopher Fang-Yen

Keyword(s):

Particle Transport ◽

High Speed ◽

Muscle Relaxation ◽

Behavioral Deficits ◽

Pumping Rate ◽

C Elegans ◽

Food Particles ◽

Weak Muscle ◽

Pharyngeal Pumping ◽

Contraction And Relaxation

AbstractThe nematode C. elegans uses rhythmic muscle contractions and relaxations called pumps to filter, transport, and crush food particles. A number of feeding mutants have been identified, including those with slow pharyngeal pumping rate, weak muscle contraction, defective muscle relaxation, and defective grinding of bacteria. Many aspects of these pharyngeal behavioral defects and how they affect pharyngeal function are not well understood. For example, the behavioral deficits underlying inefficient particle transport in ‘slippery’ mutants have been unclear. Here we use high speed video microscopy to describe pharyngeal pumping behaviors and particle transport in wild-type animals and in feeding mutants. Different ‘slippery’ mutants exhibit distinct defects including weak isthmus contraction, failure to trap particles in the anterior isthmus, and abnormal timing of contraction and relaxation in pharyngeal compartments. Our results show that multiple deficits in pharyngeal timing or contraction can cause defects in particle transport.

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Catalpol Modulates Lifespan via DAF-16/FOXO and SKN-1/Nrf2 Activation inCaenorhabditis elegans

Evidence-based Complementary and Alternative Medicine ◽

10.1155/2015/524878 ◽

2015 ◽

Vol 2015 ◽

pp. 1-10 ◽

Cited By ~ 18

Author(s):

Hyun Won Seo ◽

Se Myung Cheon ◽

Myon-Hee Lee ◽

Hong Jun Kim ◽

Hoon Jeon ◽

...

Keyword(s):

Stress Tolerance ◽

Antioxidant Enzyme Activities ◽

Related Factors ◽

Pumping Rate ◽

Resistance Proteins ◽

C Elegans ◽

Normal Culture Condition ◽

Nrf2 Activation ◽

Pharyngeal Pumping ◽

Effective Component

Catalpol is an effective component of rehmannia root and known to possess various pharmacological properties. The present study was aimed at investigating the potential effects of catalpol on the lifespan and stress tolerance usingC. elegansmodel system. Herein, catalpol showed potent lifespan extension of wild-type nematode under normal culture condition. In addition, survival rate of catalpol-fed nematodes was significantly elevated compared to untreated control under heat and oxidative stress but not under hyperosmolality conditions. We also found that elevated antioxidant enzyme activities and expressions of stress resistance proteins were attributed to catalpol-mediated increased stress tolerance of nematode. We further investigated whether catalpol’s longevity effect is related to aging-related factors including reproduction, food intake, and growth. Interestingly, catalpol exposure could attenuate pharyngeal pumping rate, indicating that catalpol may induce dietary restriction of nematode. Moreover, locomotory ability of aged nematode was significantly improved by catalpol treatment, while lipofuscin levels were attenuated, suggesting that catalpol may affect age-associated changes of nematode. Our mechanistic studies revealed thatmek-1, daf-2, age-1, daf-16, andskn-1are involved in catalpol-mediated longevity. These results indicate that catalpol extends lifespan and increases stress tolerance ofC. elegansvia DAF-16/FOXO and SKN-1/Nrf activation dependent on insulin/IGF signaling and JNK signaling.

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Functional Characterization of the Adenylyl Cyclase Genesgs-1by Analysis of a Mutational Spectrum inCaenorhabditis elegans

Genetics ◽

10.1093/genetics/161.1.133 ◽

2002 ◽

Vol 161 (1) ◽

pp. 133-142 ◽

Cited By ~ 4

Author(s):

Celine Moorman ◽

Ronald H A Plasterk

Keyword(s):

Life Span ◽

Adenylyl Cyclase ◽

Neuronal Degeneration ◽

Functional Characterization ◽

Adenylyl Cyclases ◽

Loss Of Function ◽

C Elegans ◽

Larval Stages ◽

Pharyngeal Pumping

AbstractThe sgs-1 (suppressor of activated Gαs) gene encodes one of the four adenylyl cyclases in the nematode C. elegans and is most similar to mammalian adenylyl cyclase type IX. We isolated a complete loss-of-function mutation in sgs-1 and found it to result in animals with retarded development that arrest in variable larval stages. sgs-1 mutant animals exhibit lethargic movement and pharyngeal pumping and (while not reaching adulthood) have a mean life span that is >50% extended compared to wild type. An extensive set of reduction-of-function mutations in sgs-1 was isolated in a screen for suppressors of a neuronal degeneration phenotype induced by the expression of a constitutively active version of the heterotrimeric Gαs subunit of C. elegans. Although most of these mutations change conserved residues within the catalytic domains of sgs-1, mutations in the less-conserved transmembrane domains are also found. The sgs-1 reduction-of-function mutants are viable and have reduced locomotion rates, but do not show defects in pharyngeal pumping or life span.

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Caenorhabditis elegans as an in vivo Model to Assess Amphetamine Tolerance

Brain Behavior and Evolution ◽

10.1159/000514858 ◽

2021 ◽

pp. 1-9

Author(s):

Dayana Torres Valladares ◽

Sirisha Kudumala ◽

Murad Hossain ◽

Lucia Carvelli

Keyword(s):

Caenorhabditis Elegans ◽

Molecular Mechanisms ◽

Drugs Of Abuse ◽

Genetic Model ◽

In Vivo Model ◽

C Elegans ◽

Hyperactivity Disorder ◽

In Vitro Data

Amphetamine is a potent psychostimulant also used to treat attention deficit/hyperactivity disorder and narcolepsy. In vivo and in vitro data have demonstrated that amphetamine increases the amount of extra synaptic dopamine by both inhibiting reuptake and promoting efflux of dopamine through the dopamine transporter. Previous studies have shown that chronic use of amphetamine causes tolerance to the drug. Thus, since the molecular mechanisms underlying tolerance to amphetamine are still unknown, an animal model to identify the neurochemical mechanisms associated with drug tolerance is greatly needed. Here we took advantage of a unique behavior caused by amphetamine in <i>Caenorhabditis elegans</i> to investigate whether this simple, but powerful, genetic model develops tolerance following repeated exposure to amphetamine. We found that at least 3 treatments with 0.5 mM amphetamine were necessary to see a reduction in the amphetamine-induced behavior and, thus, to promote tolerance. Moreover, we found that, after intervals of 60/90 minutes between treatments, animals were more likely to exhibit tolerance than animals that underwent 10-minute intervals between treatments. Taken together, our results show that <i>C. elegans</i> is a suitable system to study tolerance to drugs of abuse such as amphetamines.

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Neuropeptide signalling shapes feeding and reproductive behaviours in male C. elegans

10.1101/2021.11.29.470485 ◽

2021 ◽

Author(s):

Matthew J Gadenne ◽

Iris Hardege ◽

Djordji Suleski ◽

Paris Jaggers ◽

Isabel Beets ◽

...

Keyword(s):

Synaptic Connectivity ◽

Male Mating ◽

Sexually Dimorphic ◽

C Elegans ◽

Mating Efficiency ◽

Sexually Dimorphic Expression ◽

Pharyngeal Pumping ◽

Insight Into ◽

Feeding Behaviours ◽

Dimorphic Expression

Sexual dimorphism occurs where different sexes of the same species display differences in characteristics not limited to reproduction. For the nematode Caenorhabditis elegans, in which the complete neuroanatomy has been solved for both hermaphrodites and males, sexually dimorphic features have been observed both in terms of the number of neurons and in synaptic connectivity. In addition, male behaviours, such as food-leaving to prioritise searching for mates, have been attributed to neuropeptides released from sex-shared or sex-specific neurons. In this study, we show that the lury-1 neuropeptide gene shows a sexually dimorphic expression pattern; being expressed in pharyngeal neurons in both sexes but displaying additional expression in tail neurons only in the male. We also show that lury-1 mutant animals show sex differences in feeding behaviours, with pharyngeal pumping elevated in hermaphrodites but reduced in males. LURY-1 also modulates male mating efficiency, influencing motor events during contact with a hermaphrodite. Our findings indicate sex-specific roles of this peptide in feeding and reproduction in C. elegans, providing further insight into neuromodulatory control of sexually dimorphic behaviours.

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Alzheimer’s disease-relevant tau modifications selectively impact neurodegeneration and mitophagy in a novel C. elegans single-copy transgenic model

10.1101/2020.02.12.946004 ◽

2020 ◽

Cited By ~ 1

Author(s):

Sanjib Guha ◽

Sarah Fischer ◽

Gail VW Johnson ◽

Keith Nehrke

Keyword(s):

Alzheimer’S Disease ◽

Alzheimer's Disease ◽

Genetic Model ◽

Neurodegenerative Disorder ◽

Model Organism ◽

Single Copy ◽

Mitochondrial Stress ◽

C Elegans ◽

Touch Receptor Neurons ◽

New Perspective

ABSTRACTBackgroundA defining pathological hallmark of the progressive neurodegenerative disorder Alzheimer’s disease (AD) is the accumulation of misfolded tau with abnormal post-translational modifications (PTMs). These include phosphorylation at Threonine 231 (T231) and acetylation at Lysine 274 (K274) and at Lysine 281 (K281). Although tau is recognized to play a central role in pathogenesis of AD, the precise mechanisms by which these abnormal PTMs contribute to the neural toxicity of tau is unclear.MethodsHuman 0N4R tau (wild type) was expressed in touch receptor neurons of the genetic model organism C. elegans through single-copy gene insertion. Defined mutations were then introduced into the single-copy tau transgene through CRISPR-Cas9 genome editing. These mutations included T231E and T231A, to mimic phosphorylation and phospho-ablation of a commonly observed pathological epitope, respectively, and K274/281Q, to mimic disease-associated lysine acetylation. Stereotypical touch response assays were used to assess behavioral defects in the transgenic strains as a function of age, and genetically-encoded fluorescent biosensors were used to measure the morphological dynamics and turnover of touch neuron mitochondria.ResultsUnlike existing tau overexpression models, C. elegans single-copy expression of tau did not elicit overt pathological phenotypes at baseline. However, strains expressing disease associated PTM-mimetics (T231E and K274/281Q) exhibited reduced touch sensation and morphological abnormalities that increased with age. In addition, the PTM-mimetic mutants lacked the ability to engage mitophagy in response to mitochondrial stress.ConclusionsLimiting the expression of tau results in a genetic model where pathological modifications and age result in evolving phenotypes, which may more closely resemble the normal progression of AD. The finding that disease-associated PTMs suppress compensatory responses to mitochondrial stress provides a new perspective into the pathogenic mechanisms underlying AD.

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Serotonin and dopamine modulate aging in response to food perception and availability

10.1101/2021.03.23.436516 ◽

2021 ◽

Author(s):

Hillary A. Miller ◽

Shijiao Huang ◽

Megan L. Schaller ◽

Elizabeth S. Dean ◽

Angela M. Tuckowski ◽

...

Keyword(s):

Dopamine Receptors ◽

Signaling Pathway ◽

Dopamine Receptor ◽

Dietary Restriction ◽

Mammalian Cells ◽

Serotonin Receptor ◽

Enteric Neuron ◽

C Elegans ◽

Food Perception ◽

A Cell

AbstractAn organism’s ability to perceive and respond to changes in its environment is crucial for its health and survival. Here we reveal how the most well-studied longevity intervention, dietary restriction (DR), acts in-part through a cell non-autonomous signaling pathway that is inhibited by the perception of attractive smells. Using an intestinal reporter for a key gene induced by DR but suppressed by attractive smells, we identify three compounds that block food perception in C. elegans, thereby increasing longevity as DR mimetics. These compounds clearly implicate serotonin and dopamine in limiting lifespan in response to food perception. We further identify an enteric neuron in this pathway that signals through the serotonin receptor 5-HT1A/ser-4 and dopamine receptor DRD2/dop-3. Aspects of this pathway are conserved in D. melanogaster and mammalian cells. Thus, blocking food perception through antagonism of serotonin or dopamine receptors is a plausible approach to mimic the benefits of dietary restriction.

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Multiple Aspects of PIP2 Involvement in C. elegans Gametogenesis

International Journal of Molecular Sciences ◽

10.3390/ijms19092679 ◽

2018 ◽

Vol 19 (9) ◽

pp. 2679 ◽

Cited By ~ 1

Author(s):

Livia Ulicna ◽

Jana Rohozkova ◽

Pavel Hozak

Keyword(s):

Mammalian Cells ◽

Chromosome Structure ◽

Type I ◽

Nuclear Speckles ◽

C Elegans ◽

Meiotic Progression ◽

Prophase I ◽

Binding Partners ◽

Ubiquitin Proteasome ◽

Proteasome Pathway

One of the most studied phosphoinositides is phosphatidylinositol 4,5-bisphosphate (PIP2), which localizes to the plasma membrane, nuclear speckles, small foci in the nucleoplasm, and to the nucleolus in mammalian cells. Here, we show that PIP2 also localizes to the nucleus in prophase I, during the gametogenesis of C. elegans hermaphrodite. The depletion of PIP2 by type I PIP kinase (PPK-1) kinase RNA interference results in an altered chromosome structure and leads to various defects during meiotic progression. We observed a decreased brood size and aneuploidy in progeny, defects in synapsis, and crossover formation. The altered chromosome structure is reflected in the increased transcription activity of a tightly regulated process in prophase I. To elucidate the involvement of PIP2 in the processes during the C. elegans development, we identified the PIP2-binding partners, leucine-rich repeat (LRR-1) protein and proteasome subunit beta 4 (PBS-4), pointing to its involvement in the ubiquitin–proteasome pathway.

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