scholarly journals Cell cycle– and swelling-induced activation of a Caenorhabditis elegans ClC channel is mediated by CeGLC-7α/β phosphatases

2002 ◽  
Vol 158 (3) ◽  
pp. 435-444 ◽  
Author(s):  
Eric Rutledge ◽  
Jerod Denton ◽  
Kevin Strange
Keyword(s):  
Cell Cycle ◽  
Caenorhabditis Elegans ◽  
Molecular Mechanisms ◽  
Cell Swelling ◽  
Phosphatase Inhibitors ◽  
C Elegans ◽  
Physiological Processes ◽  
Cycle Dependent ◽  
Regulation Of Cell Cycle

ClC voltage-gated anion channels have been identified in bacteria, yeast, plants, and animals. The biophysical and structural properties of ClCs have been studied extensively, but relatively little is known about their precise physiological functions. Furthermore, virtually nothing is known about the signaling pathways and molecular mechanisms that regulate channel activity. The nematode Caenorhabditis elegans provides significant experimental advantages for characterizing ion channel function and regulation. We have shown previously that the ClC Cl− channel homologue CLH-3 is expressed in C. elegans oocytes, and that it is activated during meiotic maturation and by cell swelling. We demonstrate here that depletion of intracellular ATP or removal of Mg2+, experimental maneuvers that inhibit kinase function, constitutively activate CLH-3. Maturation- and swelling-induced channel activation are inhibited by type 1 serine/threonine phosphatase inhibitors. RNA interference studies demonstrated that the type 1 protein phosphatases CeGLC-7α and β, both of which play essential regulatory roles in mitotic and meiotic cell cycle events, mediate CLH-3 activation. We have suggested previously that CLH-3 and mammalian ClC-2 are orthologues that play important roles in heterologous cell–cell interactions, intercellular communication, and regulation of cell cycle–dependent physiological processes. Consistent with this hypothesis, we show that heterologously expressed rat ClC-2 is also activated by serine/threonine dephosphorylation, suggesting that the two channels have common regulatory mechanisms.

scholarly journals PAR-4/LKB1 regulates DNA replication during asynchronous division of the early C. elegans embryo

2014 ◽  
Vol 205 (4) ◽  
pp. 447-455 ◽  
Author(s):  
Laura Benkemoun ◽  
Catherine Descoteaux ◽  
Nicolas T. Chartier ◽  
Lionel Pintard ◽  
Jean-Claude Labbé
Keyword(s):  
Cell Cycle ◽  
Dna Replication ◽  
Cell Cycle Progression ◽  
Molecular Mechanisms ◽  
Control Cell ◽  
Cycle Duration ◽  
Cell Stage ◽  
C Elegans ◽  
Stage Embryo ◽  
Regulation Of Cell Cycle

Regulation of cell cycle duration is critical during development, yet the underlying molecular mechanisms are still poorly understood. The two-cell stage Caenorhabditis elegans embryo divides asynchronously and thus provides a powerful context in which to study regulation of cell cycle timing during development. Using genetic analysis and high-resolution imaging, we found that deoxyribonucleic acid (DNA) replication is asymmetrically regulated in the two-cell stage embryo and that the PAR-4 and PAR-1 polarity proteins dampen DNA replication dynamics specifically in the posterior blastomere, independently of regulators previously implicated in the control of cell cycle timing. Our results demonstrate that accurate control of DNA replication is crucial during C. elegans early embryonic development and further provide a novel mechanism by which PAR proteins control cell cycle progression during asynchronous cell division.

scholarly journals Distinct Developmental Function of Two Caenorhabditis elegans Homologs of the Cohesin Subunit Scc1/Rad21

2003 ◽  
Vol 14 (6) ◽  
pp. 2399-2409 ◽  
Author(s):  
Yoshiko Mito ◽  
Asako Sugimoto ◽  
Masayuki Yamamoto
Keyword(s):  
Cell Cycle ◽  
Caenorhabditis Elegans ◽  
Chromosome Segregation ◽  
Mitotic Chromosome ◽  
Dependent Manner ◽  
C Elegans ◽  
Late Embryogenesis ◽  
A Cell ◽  
Cohesin Subunit ◽  
Cycle Dependent

Cohesin, which mediates sister chromatid cohesion, is composed of four subunits, named Scc1/Rad21, Scc3, Smc1, and Smc3 in yeast. Caenorhabditis elegans has a single homolog for each of Scc3, Smc1, and Smc3, but as many as four for Scc1/Rad21 (COH-1, SCC-1/COH-2, COH-3, and REC-8). Except for REC-8 required for meiosis, function of these C. elegans proteins remains largely unknown. Herein, we examined their possible involvement in mitosis and development. Embryos depleted of the homolog of either Scc3, or Smc1, or Smc3 by RNA interference revealed a defect in mitotic chromosome segregation but not in chromosome condensation and cytokinesis. Depletion of SCC-1/COH-2 caused similar phenotypes. SCC-1/COH-2 was present in cells destined to divide. It localized to chromosomes in a cell cycle-dependent manner. Worms depleted of COH-1 arrested at either the late embryonic or the larval stage, with no indication of mitotic dysfunction. COH-1 associated chromosomes throughout the cell cycle in all somatic cells undergoing late embryogenesis or larval development. Thus, SCC-1/COH-2 and the homologs of Scc3, Smc1, and Smc3 facilitate mitotic chromosome segregation during the development, presumably by forming a cohesin complex, whereas COH-1 seems to play a role important for development but unrelated to mitosis.

scholarly journals Caenorhabditis elegans as an in vivo Model to Assess Amphetamine Tolerance

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.

scholarly journals Oscillatory Ca2+ Signaling in the Isolated Caenorhabditis elegans Intestine

2005 ◽  
Vol 126 (4) ◽  
pp. 379-392 ◽  
Author(s):  
Maria V. Espelt ◽  
Ana Y. Estevez ◽  
Xiaoyan Yin ◽  
Kevin Strange
Keyword(s):  
Caenorhabditis Elegans ◽  
Intestinal Epithelium ◽  
Oscillation Frequency ◽  
Gene Networks ◽  
Molecular Mechanisms ◽  
Apical Cell ◽  
Intestinal Cell ◽  
C Elegans ◽  
Contrast Gain ◽  
Behavioral Rhythm

Defecation in the nematode Caenorhabditis elegans is a readily observable ultradian behavioral rhythm that occurs once every 45–50 s and is mediated in part by posterior body wall muscle contraction (pBoc). pBoc is not regulated by neural input but instead is likely controlled by rhythmic Ca2+ oscillations in the intestinal epithelium. We developed an isolated nematode intestine preparation that allows combined physiological, genetic, and molecular characterization of oscillatory Ca2+ signaling. Isolated intestines loaded with fluo-4 AM exhibit spontaneous rhythmic Ca2+ oscillations with a period of ∼50 s. Oscillations were only detected in the apical cell pole of the intestinal epithelium and occur as a posterior-to-anterior moving intercellular Ca2+ wave. Loss-of-function mutations in the inositol-1,4,5-trisphosphate (IP3) receptor ITR-1 reduce pBoc and Ca2+ oscillation frequency and intercellular Ca2+ wave velocity. In contrast, gain-of-function mutations in the IP3 binding and regulatory domains of ITR-1 have no effect on pBoc or Ca2+ oscillation frequency but dramatically increase the speed of the intercellular Ca2+ wave. Systemic RNA interference (RNAi) screening of the six C. elegans phospholipase C (PLC)–encoding genes demonstrated that pBoc and Ca2+ oscillations require the combined function of PLC-γ and PLC-β homologues. Disruption of PLC-γ and PLC-β activity by mutation or RNAi induced arrhythmia in pBoc and intestinal Ca2+ oscillations. The function of the two enzymes is additive. Epistasis analysis suggests that PLC-γ functions primarily to generate IP3 that controls ITR-1 activity. In contrast, IP3 generated by PLC-β appears to play little or no direct role in ITR-1 regulation. PLC-β may function instead to control PIP2 levels and/or G protein signaling events. Our findings provide new insights into intestinal cell Ca2+ signaling mechanisms and establish C. elegans as a powerful model system for defining the gene networks and molecular mechanisms that underlie the generation and regulation of Ca2+ oscillations and intercellular Ca2+ waves in nonexcitable cells.

scholarly journals The Actin-Binding Protein UNC-115/abLIM Controls Formation of Lamellipodia and Filopodia and Neuronal Morphogenesis in Caenorhabditis elegans

2005 ◽  
Vol 25 (12) ◽  
pp. 5158-5170 ◽  
Author(s):  
Yieyie Yang ◽  
Erik A. Lundquist
Keyword(s):  
Caenorhabditis Elegans ◽  
Molecular Mechanisms ◽  
Binding Protein ◽  
Phosphorylation Site ◽  
Serine Phosphorylation ◽  
Actin Binding ◽  
Axon Pathfinding ◽  
Neuronal Morphogenesis ◽  
Actin Binding Protein ◽  
C Elegans

ABSTRACT The roles of actin-binding proteins in development and morphogenesis are not well understood. The actin-binding protein UNC-115 has been implicated in cytoskeletal signaling downstream of Rac in Caenorhabditis elegans axon pathfinding, but the cellular role of UNC-115 in this process remains undefined. Here we report that UNC-115 overactivity in C. elegans neurons promotes the formation of neurites and lamellipodial and filopodial extensions similar to those induced by activated Rac and normally found in C. elegans growth cones. We show that UNC-115 activity in neuronal morphogenesis is enhanced by two molecular mechanisms: when ectopically driven to the plasma membrane by the myristoylation sequence of c-Src, and by mutation of a putative serine phosphorylation site in the actin-binding domain of UNC-115. In support of the hypothesis that UNC-115 modulates actin cytoskeletal organization, we show that UNC-115 activity in serum-starved NIH 3T3 fibroblasts results in the formation of lamellipodia and filopodia. We conclude that UNC-115 is a novel regulator of the formation of lamellipodia and filopodia in neurons, possibly in the growth cone during axon pathfinding.

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 Transcriptional signature of prion-induced neurotoxicity in a Drosophila model of transmissible mammalian prion disease

2020 ◽  
Vol 477 (4) ◽  
pp. 833-852
Author(s):  
Alana M. Thackray ◽  
Brian Lam ◽  
Anisa Shahira Binti Ab Razak ◽  
Giles Yeo ◽  
Raymond Bujdoso
Keyword(s):  
Cell Cycle ◽  
Plasma Membrane ◽  
Prion Disease ◽  
Molecular Mechanisms ◽  
Control Strategies ◽  
Prion Diseases ◽  
Transcriptional Signature ◽  
Natural Hosts ◽  
Regulation Of Cell Cycle ◽  
Transgenic Drosophila

Prion diseases are fatal transmissible neurodegenerative conditions of humans and animals that arise through neurotoxicity induced by PrP misfolding. The cellular and molecular mechanisms of prion-induced neurotoxicity remain undefined. Understanding these processes will underpin therapeutic and control strategies for human and animal prion diseases, respectively. Prion diseases are difficult to study in their natural hosts and require the use of tractable animal models. Here we used RNA-Seq-based transcriptome analysis of prion-exposed Drosophila to probe the mechanism of prion-induced neurotoxicity. Adult Drosophila transgenic for pan neuronal expression of ovine PrP targeted to the plasma membrane exhibit a neurotoxic phenotype evidenced by decreased locomotor activity after exposure to ovine prions at the larval stage. Pathway analysis and quantitative PCR of genes differentially expressed in prion-infected Drosophila revealed up-regulation of cell cycle activity and DNA damage response, followed by down-regulation of eIF2 and mTOR signalling. Mitochondrial dysfunction was identified as the principal toxicity pathway in prion-exposed PrP transgenic Drosophila. The transcriptomic changes we observed were specific to PrP targeted to the plasma membrane since these prion-induced gene expression changes were not evident in similarly treated Drosophila transgenic for cytosolic pan neuronal PrP expression, or in non-transgenic control flies. Collectively, our data indicate that aberrant cell cycle activity, repression of protein synthesis and altered mitochondrial function are key events involved in prion-induced neurotoxicity, and correlate with those identified in mammalian hosts undergoing prion disease. These studies highlight the use of PrP transgenic Drosophila as a genetically well-defined tractable host to study mammalian prion biology.

scholarly journals Gcn5-mediated acetylation at MBF-regulated promoters induces the G1/S transcriptional wave

2019 ◽  
Vol 47 (16) ◽  
pp. 8439-8451 ◽  
Author(s):  
Alberto González-Medina ◽  
Elena Hidalgo ◽  
José Ayté
Keyword(s):  
Cell Cycle ◽  
Molecular Mechanisms ◽  
Histone H3 ◽  
Dependent Manner ◽  
Saga Complex ◽  
Lysine Residues ◽  
Physical Barriers ◽  
A Cell ◽  
Cycle Dependent ◽  
Regulated Promoters

Abstract In fission yeast, MBF-dependent transcription is inactivated at the end of S phase through a negative feedback loop that involves the co-repressors, Yox1 and Nrm1. Although this repression system is well known, the molecular mechanisms involved in MBF activation remain largely unknown. Compacted chromatin constitutes a barrier to activators accessing promoters. Here, we show that chromatin regulation plays a key role in activating MBF-dependent transcription. Gcn5, a part of the SAGA complex, binds to MBF-regulated promoters through the MBF co-activator Rep2 in a cell cycle-dependent manner and in a reverse correlation to the binding of the MBF co-repressors, Nrm1 or Yox1. We propose that the co-repressors function as physical barriers to SAGA recruitment onto MBF promoters. We also show that Gcn5 acetylates specific lysine residues on histone H3 in a cell cycle-regulated manner. Furthermore, either in a gcn5 mutant or in a strain in which histone H3 is kept in an unacetylated form, MBF-dependent transcription is downregulated. In summary, Gcn5 is required for the full activation and correct timing of MBF-regulated gene transcription.

scholarly journals Inducible Systemic RNA Silencing in Caenorhabditis elegans

2003 ◽  
Vol 14 (7) ◽  
pp. 2972-2983 ◽  
Author(s):  
Lisa Timmons ◽  
Hiroaki Tabara ◽  
Craig C. Mello ◽  
Andrew Z. Fire
Keyword(s):  
Rna Interference ◽  
Caenorhabditis Elegans ◽  
Rna Silencing ◽  
Molecular Mechanisms ◽  
Normal Animal ◽  
Cell Types ◽  
Animal Cells ◽  
Tissue Specific ◽  
C Elegans ◽  
Systemic Rna

Introduction of double-stranded RNA (dsRNA) can elicit a gene-specific RNA interference response in a variety of organisms and cell types. In many cases, this response has a systemic character in that silencing of gene expression is observed in cells distal from the site of dsRNA delivery. The molecular mechanisms underlying the mobile nature of RNA silencing are unknown. For example, although cellular entry of dsRNA is possible, cellular exit of dsRNA from normal animal cells has not been directly observed. We provide evidence that transgenic strains of Caenorhabditis elegans transcribing dsRNA from a tissue-specific promoter do not exhibit comprehensive systemic RNA interference phenotypes. In these same animals, modifications of environmental conditions can result in more robust systemic RNA silencing. Additionally, we find that genetic mutations can influence the systemic character of RNA silencing in C. elegans and can separate mechanisms underlying systemic RNA silencing into tissue-specific components. These data suggest that trafficking of RNA silencing signals in C. elegans is regulated by specific physiological and genetic factors.

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