LET-711, the Caenorhabditis elegans NOT1 Ortholog, Is Required for Spindle Positioning and Regulation of Microtubule Length in Embryos

Spindle positioning is essential for the segregation of cell fate determinants during asymmetric division, as well as for proper cellular arrangements during development. In Caenorhabditis elegans embryos, spindle positioning depends on interactions between the astral microtubules and the cell cortex. Here we show that let-711 is required for spindle positioning in the early embryo. Strong loss of let-711 function leads to sterility, whereas partial loss of function results in embryos with defects in the centration and rotation movements that position the first mitotic spindle. let-711 mutant embryos have longer microtubules that are more cold-stable than in wild type, a phenotype opposite to the short microtubule phenotype caused by mutations in the C. elegans XMAP215 homolog ZYG-9. Simultaneous reduction of both ZYG-9 and LET-711 can rescue the centration and rotation defects of both single mutants. let-711 mutant embryos also have larger than wild-type centrosomes at which higher levels of ZYG-9 accumulate compared with wild type. Molecular identification of LET-711 shows it to be an ortholog of NOT1, the core component of the CCR4/NOT complex, which plays roles in the negative regulation of gene expression at transcriptional and post-transcriptional levels in yeast, flies, and mammals. We therefore propose that LET-711 inhibits the expression of ZYG-9 and potentially other centrosome-associated proteins, in order to maintain normal centrosome size and microtubule dynamics during early embryonic divisions.

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Goα Regulates Volatile Anesthetic Action in Caenorhabditis elegans

Genetics ◽

10.1093/genetics/158.2.643 ◽

2001 ◽

Vol 158 (2) ◽

pp. 643-655 ◽

Cited By ~ 1

Author(s):

Bruno van Swinderen ◽

Laura B Metz ◽

Laynie D Shebester ◽

Jane E Mendel ◽

Paul W Sternberg ◽

...

Keyword(s):

Caenorhabditis Elegans ◽

Novel Mutation ◽

Volatile Anesthetic ◽

Loss Of Function ◽

Wild Type ◽

Α Subunit ◽

C Elegans ◽

Missense Mutant ◽

Anesthetic Action ◽

Mutant Phenotypes

Abstract To identify genes controlling volatile anesthetic (VA) action, we have screened through existing Caenorhabditis elegans mutants and found that strains with a reduction in Go signaling are VA resistant. Loss-of-function mutants of the gene goa-1, which codes for the α-subunit of Go, have EC50s for the VA isoflurane of 1.7- to 2.4-fold that of wild type. Strains overexpressing egl-10, which codes for an RGS protein negatively regulating goa-1, are also isoflurane resistant. However, sensitivity to halothane, a structurally distinct VA, is differentially affected by Go pathway mutants. The RGS overexpressing strains, a goa-1 missense mutant found to carry a novel mutation near the GTP-binding domain, and eat-16(rf) mutants, which suppress goa-1(gf) mutations, are all halothane resistant; goa-1(null) mutants have wild-type sensitivities. Double mutant strains carrying mutations in both goa-1 and unc-64, which codes for a neuronal syntaxin previously found to regulate VA sensitivity, show that the syntaxin mutant phenotypes depend in part on goa-1 expression. Pharmacological assays using the cholinesterase inhibitor aldicarb suggest that VAs and GOA-1 similarly downregulate cholinergic neurotransmitter release in C. elegans. Thus, the mechanism of action of VAs in C. elegans is regulated by Goα, and presynaptic Goα-effectors are candidate VA molecular targets.

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Regulators of the Actin Cytoskeleton Mediate Lethality in a Caenorhabditis elegans dhc-1 Mutant

Molecular Biology of the Cell ◽

10.1091/mbc.e09-07-0593 ◽

2010 ◽

Vol 21 (15) ◽

pp. 2707-2720 ◽

Cited By ~ 4

Author(s):

Aleksandra J. Gil-Krzewska ◽

Erica Farber ◽

Edgar A. Buttner ◽

Craig P. Hunter

Keyword(s):

Caenorhabditis Elegans ◽

Actin Cytoskeleton ◽

Cytoplasmic Dynein ◽

Loss Of Function ◽

Cellular Functions ◽

Capping Protein ◽

C Elegans ◽

Wide Range ◽

Actin Capping Protein ◽

Associated Proteins

Functional analysis of cytoplasmic dynein in Caenorhabditis elegans has revealed a wide range of cellular functions for this minus-end–directed motor protein. Dynein transports a variety of cargos to diverse cellular locations, and thus cargo selection and destination are likely regulated by accessory proteins. The microtubule-associated proteins LIS-1 and dynein interact, but the nature of this interaction remains poorly understood. Here we show that both LIS-1 and the dynein heavy-chain DHC-1 are required for integrity of the actin cytoskeleton in C. elegans. Although both dhc-1(or195ts) and lis-1 loss-of-function disrupt the actin cytoskeleton and produce embryonic lethality, a double mutant suppresses these defects. A targeted RNA interference screen revealed that knockdown of other actin regulators, including actin-capping protein genes and prefoldin subunit genes, suppresses dhc-1(or195ts)–induced lethality. We propose that release or relocation of the mutant dynein complex mediates this suppression of dhc-1(or195ts)--induced phenotypes. These results reveal an unexpected direct or indirect interaction between the actin cytoskeleton and dynein activity.

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Promoters of the dhs-21 gene encoding dicarbonyl/l-xylulose reductase in Caenorhabditis elegans

Vietnam Journal of Biotechnology ◽

10.15625/1811-4989/15/2/12353 ◽

2018 ◽

Vol 15 (2) ◽

pp. 359-365

Author(s):

Lê Thọ Sơn ◽

Joohong Ahnn ◽

Jeong Hoon Cho ◽

Nguyễn Huy Hoàng

Keyword(s):

Caenorhabditis Elegans ◽

Model Organism ◽

Biological Research ◽

Loss Of Function ◽

Wild Type ◽

C Elegans ◽

Larval Stages ◽

Vital Functions

Dicarbonyl/L-xylulose (DCXR) was identified as a dehydrogenase. This type of enzyme was presented in various forms of lives including bacteria, fungi, plants and animals. Generally, it converts L-xylulose to xylitol in the presence of either cofactor NADH or NADPH in vitro. Previous studies reported the biochemistry properties and crystal structure but largely uncovered biological roles of DCXRs. It was impossible to dissect the functions in mice or human cells that had many DCXR homologs in their genomes. Interestingly, the wild-type Caenorhabditis elegans, a well-known model organism in biological research, has only nuclear genomic dhs-21 that encodes a unique homologous DCXR. Thus Ce.dhs-21 and the host C. elegans were relevant for investigation of the physiologically-vital functions of the DCXR. This research aimed to the expression of dhs-21 in vivo. We defined three promoters , manipulated three relative reporter-constructs that conjugated the dhs-21 gene and Green Flouresent Protein (known as GFP) one. The construct vectors were transferred into wild-type C. elegans N2 and as well as the hermaphroditic loss of function dhs-21(jh129) by microinjection. In the results, we found that the expression pattern of dhs-21 under the only p2-promoter construct was stable and similar to immunogold Electric Microscopy (EM) images. The dhs-21 gene was expressed in both sexes of at all larval stages till the deaths of worms. DHS-21 was expressed in the cytosol of the intestinal, gonad sheath and uterous seam cell (utse).

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Mechanisms of Spindle Positioning: Lessons from Worms and Mammalian Cells

Biomolecules ◽

10.3390/biom9020080 ◽

2019 ◽

Vol 9 (2) ◽

pp. 80 ◽

Cited By ~ 16

Author(s):

Sachin Kotak

Keyword(s):

Cell Fate ◽

Protein Interactions ◽

Mitotic Spindle ◽

Mammalian Cells ◽

Physical Nature ◽

Cell Cortex ◽

Protein Protein Interactions ◽

Spindle Positioning ◽

Cellular Environment ◽

Associated Proteins

Proper positioning of the mitotic spindle is fundamental for specifying the site for cleavage furrow, and thus regulates the appropriate sizes and accurate distribution of the cell fate determinants in the resulting daughter cells during development and in the stem cells. The past couple of years have witnessed tremendous work accomplished in the area of spindle positioning, and this has led to the emergence of a working model unravelling in-depth mechanistic insight of the underlying process orchestrating spindle positioning. It is evident now that the correct positioning of the mitotic spindle is not only guided by the chemical cues (protein–protein interactions) but also influenced by the physical nature of the cellular environment. In metazoans, the key players that regulate proper spindle positioning are the actin-rich cell cortex and associated proteins, the ternary complex (Gα/GPR-1/2/LIN-5 in Caenorhabditis elegans, Gαi/Pins/Mud in Drosophila and Gαi1-3/LGN/NuMA in humans), minus-end-directed motor protein dynein and the cortical machinery containing myosin. In this review, I will mainly discuss how the abovementioned components precisely and spatiotemporally regulate spindle positioning by sensing the physicochemical environment for execution of flawless mitosis.

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Enhancers of glp-1, a gene required for cell-signaling in Caenorhabditis elegans, define a set of genes required for germline development.

Genetics ◽

10.1093/genetics/141.2.551 ◽

1995 ◽

Vol 141 (2) ◽

pp. 551-569 ◽

Cited By ~ 9

Author(s):

L Qiao ◽

J L Lissemore ◽

P Shu ◽

A Smardon ◽

M B Gelber ◽

...

Keyword(s):

Caenorhabditis Elegans ◽

Cell Signaling ◽

Cell Fate ◽

Gene Families ◽

Loss Of Function ◽

Germline Development ◽

Somatic Development ◽

C Elegans ◽

Functional Relationships ◽

New Genes

Abstract The distal tip cell (DTC) regulates the proliferation or differentiation choice in the Caenorhabditis elegans germline by an inductive mechanism. Cell signaling requires a putative receptor in the germline, encoded b y the glp-1 gene, and a putative signal from the DTC, encoded by the lag-2 gene. Both glp-1 and lag-2 belong to multigene gene families whose members are essential for cell signaling during development of various tissues in insects and vertebrates as well as C. elegans. Relatively little is known about how these pathways regulate cell fate choice. To identify additional genes involved in the glp-1 signaling pathway, we carried out screens for genetic enhancers of glp-1. We recovered mutations in five new genes, named ego (enhancer of glp-1), and two previously identified genes, lag-1 and glp-4, that strongly enhance a weak glp-1 loss-of-function phenotype in the germline. Ego mutations cause multiple phenotypes consistent with the idea that gene activity is required for more than one aspect of germline and, in some cases, somatic development. Based on genetic experiments, glp-1 appears to act upstream of ego-1 and ego-3. We discuss the possible functional relationships among these genes in light of their phenotypes and interactions with glp-1.

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β-Filagenin, a Newly Identified Protein Coassembling with Myosin and Paramyosin in Caenorhabditis elegans

The Journal of Cell Biology ◽

10.1083/jcb.140.2.347 ◽

1998 ◽

Vol 140 (2) ◽

pp. 347-353 ◽

Cited By ~ 13

Author(s):

Feizhou Liu ◽

Christopher C. Bauer ◽

Irving Ortiz ◽

Richard G. Cook ◽

Michael F. Schmid ◽

...

Keyword(s):

Caenorhabditis Elegans ◽

Core Protein ◽

Aromatic Amino Acids ◽

Thick Filament ◽

Wild Type ◽

C Elegans ◽

The Core ◽

Core Proteins ◽

Associated Proteins ◽

The Stability

Muscle thick filaments are stable assemblies of myosin and associated proteins whose dimensions are precisely regulated. The mechanisms underlying the stability and regulation of the assembly are not understood. As an approach to these problems, we have studied the core proteins that, together with paramyosin, form the core structure of the thick filament backbone in the nematode Caenorhabditis elegans. We obtained partial peptide sequences from one of the core proteins, β-filagenin, and then identified a gene that encodes a novel protein of 201–amino acid residues from databases using these sequences. β-Filagenin has a calculated isoelectric point at 10.61 and a high percentage of aromatic amino acids. Secondary structure algorithms predict that it consists of four β-strands but no α-helices. Western blotting using an affinity-purified antibody showed that β-filagenin was associated with the cores. β-Filagenin was localized by immunofluorescence microscopy to the A bands of body–wall muscles, but not the pharynx. β-filagenin assembled with the myosin homologue paramyosin into the tubular cores of wild-type nematodes at a periodicity matching the 72-nm repeats of paramyosin, as revealed by immunoelectron microscopy. In CB1214 mutants where paramyosin is absent, β-filagenin assembled with myosin to form abnormal tubular filaments with a periodicity identical to wild type. These results verify that β-filagenin is a core protein that coassembles with either myosin or paramyosin in C. elegans to form tubular filaments.

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Centrosome Aurora A gradient ensures single polarity axis in C. elegans embryos

Biochemical Society Transactions ◽

10.1042/bst20200298 ◽

2020 ◽

Vol 48 (3) ◽

pp. 1243-1253 ◽

Cited By ~ 1

Author(s):

Sukriti Kapoor ◽

Sachin Kotak

Keyword(s):

Symmetry Breaking ◽

Cell Fate ◽

Cell Cortex ◽

Axis Formation ◽

Aurora A Kinase ◽

Aurora A ◽

C Elegans ◽

Cell Embryo ◽

Polarity Establishment

Cellular asymmetries are vital for generating cell fate diversity during development and in stem cells. In the newly fertilized Caenorhabditis elegans embryo, centrosomes are responsible for polarity establishment, i.e. anterior–posterior body axis formation. The signal for polarity originates from the centrosomes and is transmitted to the cell cortex, where it disassembles the actomyosin network. This event leads to symmetry breaking and the establishment of distinct domains of evolutionarily conserved PAR proteins. However, the identity of an essential component that localizes to the centrosomes and promotes symmetry breaking was unknown. Recent work has uncovered that the loss of Aurora A kinase (AIR-1 in C. elegans and hereafter referred to as Aurora A) in the one-cell embryo disrupts stereotypical actomyosin-based cortical flows that occur at the time of polarity establishment. This misregulation of actomyosin flow dynamics results in the occurrence of two polarity axes. Notably, the role of Aurora A in ensuring a single polarity axis is independent of its well-established function in centrosome maturation. The mechanism by which Aurora A directs symmetry breaking is likely through direct regulation of Rho-dependent contractility. In this mini-review, we will discuss the unconventional role of Aurora A kinase in polarity establishment in C. elegans embryos and propose a refined model of centrosome-dependent symmetry breaking.

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The Effect of Mianserin on Lifespan of Caenorhabditis elegans is Abolished by Glucose

Current Aging Science ◽

10.2174/1874609813999210104203614 ◽

2021 ◽

Vol 13 ◽

Author(s):

Abdullah Almotayri ◽

Jency Thomas ◽

Mihiri Munasinghe ◽

Markandeya Jois

Keyword(s):

Caenorhabditis Elegans ◽

Scaffolding Protein ◽

Lifespan Extension ◽

Wild Type ◽

E Coli ◽

C Elegans ◽

Risk Of Death ◽

Increased Risk ◽

Antidepressant Use ◽

Extension Effect

Background: The antidepressant mianserin has been shown to extend the lifespan of Caenorhabditis elegans (C. elegans), a well-established model organism used in aging research. The extension of lifespan in C. elegans was shown to be dependent on increased expression of the scaffolding protein (ANK3/unc-44). In contrast, antidepressant use in humans is associated with an increased risk of death. The C. elegans in the laboratory are fed Escherichia coli (E. coli), a diet high in protein and low in carbohydrate, whereas a typical human diet is high in carbohydrates. We hypothesized that dietary carbohydrates might mitigate the lifespan-extension effect of mianserin. Objective: To investigate the effect of glucose added to the diet of C. elegans on the lifespan-extension effect of mianserin. Methods: Wild-type Bristol N2 and ANK3/unc-44 inactivating mutants were cultured on agar plates containing nematode growth medium and fed E. coli. Treatment groups included (C) control, (M50) 50 μM mianserin, (G) 73 mM glucose, and (M50G) 50 μM mianserin and 73 mM glucose. Lifespan was determined by monitoring the worms until they died. Statistical analysis was performed using the Kaplan-Meier version of the log-rank test. Results: Mianserin treatment resulted in a 12% increase in lifespan (P<0.05) of wild-type Bristol N2 worms but reduced lifespan by 6% in ANK3/unc-44 mutants, consistent with previous research. The addition of glucose to the diet reduced the lifespan of both strains of worms and abolished the lifespan-extension by mianserin. Conclusion: The addition of glucose to the diet of C. elegans abolishes the lifespan-extension effects of mianserin.

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The NALCN Channel Regulator UNC-80 Functions in a Subset of Interneurons To Regulate Caenorhabditis elegans Reversal Behavior

G3 Genes|Genome|Genetics ◽

10.1534/g3.119.400692 ◽

2019 ◽

Vol 10 (1) ◽

pp. 199-210 ◽

Cited By ~ 1

Author(s):

Chuanman Zhou ◽

Jintao Luo ◽

Xiaohui He ◽

Qian Zhou ◽

Yunxia He ◽

...

Keyword(s):

Plant Hormone ◽

Neuronal Excitability ◽

Resting Membrane Potential ◽

Loss Of Function ◽

Wild Type ◽

C Elegans ◽

Link Type ◽

Complex Functions ◽

And Function ◽

Multiple Loss

NALCN (Na+leak channel, non-selective) is a conserved, voltage-insensitive cation channel that regulates resting membrane potential and neuronal excitability. UNC79 and UNC80 are key regulators of the channel function. However, the behavioral effects of the channel complex are not entirely clear and the neurons in which the channel functions remain to be identified. In a forward genetic screen for C. elegans mutants with defective avoidance response to the plant hormone methyl salicylate (MeSa), we isolated multiple loss-of-function mutations in unc-80 and unc-79. C. elegans NALCN mutants exhibited similarly defective MeSa avoidance. Interestingly, NALCN, unc-80 and unc-79 mutants all showed wild type-like responses to other attractive or repelling odorants, suggesting that NALCN does not broadly affect odor detection or related forward and reversal behaviors. To understand in which neurons the channel functions, we determined the identities of a subset of unc-80-expressing neurons. We found that unc-79 and unc-80 are expressed and function in overlapping neurons, which verified previous assumptions. Neuron-specific transgene rescue and knockdown experiments suggest that the command interneurons AVA and AVE and the anterior guidepost neuron AVG can play a sufficient role in mediating unc-80 regulation of the MeSa avoidance. Though primarily based on genetic analyses, our results further imply that MeSa might activate NALCN by direct or indirect actions. Altogether, we provide an initial look into the key neurons in which the NALCN channel complex functions and identify a novel function of the channel in regulating C. elegans reversal behavior through command interneurons.

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Sperm Competition in the Absence of Fertilization in Caenorhabditis elegans

Genetics ◽

10.1093/genetics/152.1.201 ◽

1999 ◽

Vol 152 (1) ◽

pp. 201-208 ◽

Cited By ~ 2

Author(s):

Andrew Singson ◽

Katherine L Hill ◽

Steven W L’Hernault

Keyword(s):

Caenorhabditis Elegans ◽

Sperm Competition ◽

Sperm Function ◽

Sperm Precedence ◽

Wild Type ◽

Nematode Caenorhabditis Elegans ◽

C Elegans ◽

Normal Sperm ◽

Self Fertilization ◽

Competition Assays

Abstract Hermaphrodite self-fertilization is the primary mode of reproduction in the nematode Caenorhabditis elegans. However, when a hermaphrodite is crossed with a male, nearly all of the oocytes are fertilized by male-derived sperm. This sperm precedence during reproduction is due to the competitive superiority of male-derived sperm and results in a functional suppression of hermaphrodite self-fertility. In this study, mutant males that inseminate fertilization-defective sperm were used to reveal that sperm competition within a hermaphrodite does not require successful fertilization. However, sperm competition does require normal sperm motility. Additionally, sperm competition is not an absolute process because oocytes not fertilized by male-derived sperm can sometimes be fertilized by hermaphrodite-derived sperm. These results indicate that outcrossed progeny result from a wild-type cross because male-derived sperm are competitively superior and hermaphrodite-derived sperm become unavailable to oocytes. The sperm competition assays described in this study will be useful in further classifying the large number of currently identified mutations that alter sperm function and development in C. elegans.

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