scholarly journals RACK-1 Directs Dynactin-dependent RAB-11 Endosomal Recycling during Mitosis in Caenorhabditis elegans

2009 ◽  
Vol 20 (6) ◽  
pp. 1629-1638 ◽  
Author(s):  
Erkang Ai ◽  
Daniel S. Poole ◽  
Ahna R. Skop
Keyword(s):  
Cell Cycle ◽  
Caenorhabditis Elegans ◽  
Membrane Trafficking ◽  
Animal Cells ◽  
Recycling Endosomes ◽  
C Elegans ◽  
Astral Microtubule ◽  
Endosomal Recycling ◽  
Chromosome Separation ◽  
Dynactin Complex

Membrane trafficking pathways are necessary for the addition and removal of membrane during cytokinesis. In animal cells, recycling endosomes act as a major source of the additional membranes during furrow progression and abscission. However, the mechanisms and factors that regulate recycling endosomes during the cell cycle remain poorly understood. Here, we show that the Caenorhabditis elegans Receptor of Activated C Kinase 1 (RACK-1) is required for cytokinesis, germline membrane organization, and the recruitment of RAB-11–labeled recycling endosomes to the pericentrosomal region and spindle. RACK-1 is also required for proper chromosome separation and astral microtubule length. RACK-1 localizes to the centrosomes, kinetochores, the midbody, and nuclear envelopes during the cell cycle. We found that RACK-1 directly binds to DNC-2, the C. elegans p50/dynamitin subunit of the dynactin complex. Last, RACK-1 may facilitate the sequestration of recycling endosomes by targeting DNC-2 to centrosomes and the spindle. Our findings suggest a mechanism by which RACK-1 directs the dynactin-dependent redistribution of recycling endosomes during the cell cycle, thus ensuring proper membrane trafficking events during cytokinesis.

scholarly journals Regulation of Membrane Trafficking by a Novel Cdc42-related Protein in Caenorhabditis elegans Epithelial Cells

2005 ◽  
Vol 16 (4) ◽  
pp. 1629-1639 ◽  
Author(s):  
S. Jenna ◽  
M.-E. Caruso ◽  
A. Emadali ◽  
D. T. Nguyên ◽  
M. Dominguez ◽  
...  
Keyword(s):  
Caenorhabditis Elegans ◽  
Epithelial Cells ◽  
Membrane Trafficking ◽  
Rho Gtpases ◽  
Related Protein ◽  
Recycling Endosomes ◽  
C Elegans ◽  
Apical Trafficking ◽  
Golgi Network

Rho GTPases are mainly known for their implication in cytoskeleton remodeling. They have also been recently shown to regulate various aspects of membrane trafficking. Here, we report the identification and the characterization of a novel Caenorhabditis elegans Cdc42-related protein, CRP-1, that shows atypical enzymatic characteristics in vitro. Expression in mouse fibroblasts revealed that, in contrast with CDC-42, CRP-1 was unable to reorganize the actin cytoskeleton and mainly localized to trans-Golgi network and recycling endosomes. This subcellular localization, as well as its expression profile restricted to a subset of epithelial-like cells in C. elegans, suggested a potential function for this protein in polarized membrane trafficking. Consistent with this hypothesis, alteration of CRP-1 expression affected the apical trafficking of CHE-14 in vulval and rectal epithelial cells and sphingolipids (C6-NBD-ceramide) uptake and/or trafficking in intestinal cells. However, it did not affect basolateral trafficking of myotactin in the pharynx and the targeting of IFB-2 and AJM-1, two cytosolic apical markers of intestine epithelial cells. Hence, our data demonstrate a function for CRP-1 in the regulation of membrane trafficking in a subset of cells with epithelial characteristics.

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.

scholarly journals Intracellular organelles mediate cytoplasmic pulling force for centrosome centration in the Caenorhabditis elegans early embryo

2010 ◽  
Vol 108 (1) ◽  
pp. 137-142 ◽  
Author(s):  
Kenji Kimura ◽  
Akatsuki Kimura
Keyword(s):  
Caenorhabditis Elegans ◽  
Mammalian Cells ◽  
Cytoplasmic Dynein ◽  
Early Embryo ◽  
Organelle Transport ◽  
Animal Cells ◽  
C Elegans ◽  
Cell Functions ◽  
Intracellular Organelles ◽  
Pulling Force

The centrosome is generally maintained at the center of the cell. In animal cells, centrosome centration is powered by the pulling force of microtubules, which is dependent on cytoplasmic dynein. However, it is unclear how dynein brings the centrosome to the cell center, i.e., which structure inside the cell functions as a substrate to anchor dynein. Here, we provide evidence that a population of dynein, which is located on intracellular organelles and is responsible for organelle transport toward the centrosome, generates the force required for centrosome centration in Caenorhabditis elegans embryos. By using the database of full-genome RNAi in C. elegans, we identified dyrb-1, a dynein light chain subunit, as a potential subunit involved in dynein anchoring for centrosome centration. DYRB-1 is required for organelle movement toward the minus end of the microtubules. The temporal correlation between centrosome centration and the net movement of organelle transport was found to be significant. Centrosome centration was impaired when Rab7 and RILP, which mediate the association between organelles and dynein in mammalian cells, were knocked down. These results indicate that minus end-directed transport of intracellular organelles along the microtubules is required for centrosome centration in C. elegans embryos. On the basis of this finding, we propose a model in which the reaction forces of organelle transport generated along microtubules act as a driving force that pulls the centrosomes toward the cell center. This is the first model, to our knowledge, providing a mechanical basis for cytoplasmic pulling force for centrosome centration.

scholarly journals Suspended Animation Extends Survival Limits of Caenorhabditis elegans and Saccharomyces cerevisiae at Low Temperature

2010 ◽  
Vol 21 (13) ◽  
pp. 2161-2171 ◽  
Author(s):  
Kin Chan ◽  
Jesse P. Goldmark ◽  
Mark B. Roth
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Cycle ◽  
Cell Division ◽  
Caenorhabditis Elegans ◽  
Cell Division Cycle ◽  
Wild Type ◽  
Suspended Animation ◽  
C Elegans ◽  
High Viability ◽  
Cold Sensitive

The orderly progression through the cell division cycle is of paramount importance to all organisms, as improper progression through the cycle could result in defects with grave consequences. Previously, our lab has shown that model eukaryotes such as Saccharomyces cerevisiae, Caenorhabditis elegans, and Danio rerio all retain high viability after prolonged arrest in a state of anoxia-induced suspended animation, implying that in such a state, progression through the cell division cycle is reversibly arrested in an orderly manner. Here, we show that S. cerevisiae (both wild-type and several cold-sensitive strains) and C. elegans embryos exhibit a dramatic decrease in viability that is associated with dysregulation of the cell cycle when exposed to low temperatures. Further, we find that when the yeast or worms are first transitioned into a state of anoxia-induced suspended animation before cold exposure, the associated cold-induced viability defects are largely abrogated. We present evidence that by imposing an anoxia-induced reversible arrest of the cell cycle, the cells are prevented from engaging in aberrant cell cycle events in the cold, thus allowing the organisms to avoid the lethality that would have occurred in a cold, oxygenated environment.

scholarly journals A deletion polymorphism in the Caenorhabditis elegans RIG-I homolog disables viral RNA dicing and antiviral immunity

eLife ◽  
2013 ◽  
Vol 2 ◽  
Author(s):  
Alyson Ashe ◽  
Tony Bélicard ◽  
Jérémie Le Pen ◽  
Peter Sarkies ◽  
Lise Frézal ◽  
...  
Keyword(s):  
Caenorhabditis Elegans ◽  
Genome Wide Association Study ◽  
Rna Virus ◽  
Rnai Pathway ◽  
Animal Cells ◽  
C Elegans ◽  
Base Pair Deletion ◽  
A Genome ◽  
Positive Strand Rna ◽  
Viral Recognition

RNA interference defends against viral infection in plant and animal cells. The nematode Caenorhabditis elegans and its natural pathogen, the positive-strand RNA virus Orsay, have recently emerged as a new animal model of host-virus interaction. Using a genome-wide association study in C. elegans wild populations and quantitative trait locus mapping, we identify a 159 base-pair deletion in the conserved drh-1 gene (encoding a RIG-I-like helicase) as a major determinant of viral sensitivity. We show that DRH-1 is required for the initiation of an antiviral RNAi pathway and the generation of virus-derived siRNAs (viRNAs). In mammals, RIG-I-domain containing proteins trigger an interferon-based innate immunity pathway in response to RNA virus infection. Our work in C. elegans demonstrates that the RIG-I domain has an ancient role in viral recognition. We propose that RIG-I acts as modular viral recognition factor that couples viral recognition to different effector pathways including RNAi and interferon responses.

The Caenorhabditis elegans gene ncc-1 encodes a cdc2-related kinase required for M phase in meiotic and mitotic cell divisions, but not for S phase

Development ◽  
1999 ◽  
Vol 126 (10) ◽  
pp. 2227-2239 ◽  
Author(s):  
M. Boxem ◽  
D.G. Srinivasan ◽  
S. van den Heuvel
Keyword(s):  
Cell Cycle ◽  
Caenorhabditis Elegans ◽  
Cell Cycle Progression ◽  
Mitotic Cell ◽  
S Phase ◽  
C Elegans ◽  
Nuclear Envelope Breakdown ◽  
Cell Divisions ◽  
M Phase ◽  
Single Transition

We have identified six protein kinases that belong to the family of cdc2-related kinases in Caenorhabditis elegans. Results from RNA interference experiments indicate that at least one of these kinases is required for cell-cycle progression during meiosis and mitosis. This kinase, encoded by the ncc-1 gene, is closely related to human Cdk1/Cdc2, Cdk2 and Cdk3 and yeast CDC28/cdc2(+). We addressed whether ncc-1 acts to promote passage through a single transition or multiple transitions in the cell cycle, analogous to Cdks in vertebrates or yeasts, respectively. We isolated five recessive ncc-1 mutations in a genetic screen for mutants that resemble larval arrested ncc-1(RNAi) animals. Our results indicate that maternal ncc-1 product is sufficient for embryogenesis, and that zygotic expression is required for cell divisions during larval development. Cells that form the postembryonic lineages in wild-type animals do not enter mitosis in ncc-1 mutants, as indicated by lack of chromosome condensation and nuclear envelope breakdown. However, progression through G1 and S phase appears unaffected, as revealed by expression of ribonucleotide reductase, incorporation of BrdU and DNA quantitation. Our results indicate that C. elegans uses multiple Cdks to regulate cell-cycle transitions and that ncc-1 is the C. elegans ortholog of Cdk1/Cdc2 in other metazoans, required for M phase in meiotic as well as mitotic cell cycles.

Three genes of the MAP kinase cascade, mek-2, mpk-1/sur-1 and let-60 ras, are required for meiotic cell cycle progression in Caenorhabditis elegans

Development ◽  
1995 ◽  
Vol 121 (8) ◽  
pp. 2525-2535 ◽  
Author(s):  
D.L. Church ◽  
K.L. Guan ◽  
E.J. Lambie
Keyword(s):  
Cell Cycle ◽  
Caenorhabditis Elegans ◽  
Map Kinase ◽  
Germ Cells ◽  
Cell Cycle Progression ◽  
Extended Period ◽  
Meiotic Cell ◽  
Cycle Progression ◽  
C Elegans ◽  
Genetic Mosaic

In the germline of Caenorhabditis elegans hermaphrodites, meiotic cell cycle progression occurs in spatially restricted regions. Immediately after leaving the distal mitotic region, germ cells enter meiosis and thereafter remain in the pachytene stage of first meiotic prophase for an extended period. At the dorsoventral gonadal flexure, germ cells exit pachytene and subsequently become arrested in diakinesis. We have found that exit from pachytene is dependent on the function of three members of the MAP kinase signaling cascade. One of these genes, mek-2, is a newly identified C. elegans MEK (MAP kinase kinase). The other two genes, mpk-1/sur-1 (MAP kinase) and let-60 ras, were previously identified based on their roles in vulval induction and are shown here to act in combination with mek-2 to permit exit from pachytene. Through genetic mosaic analysis, we demonstrate that the expression of mpk-1/sur-1 is required within the germline to permit exit from pachytene.

scholarly journals The atypical Rho GTPase RhoU interacts with intersectin-2 to regulate endosomal recycling pathways

2020 ◽  
Vol 133 (16) ◽  
pp. jcs234104
Author(s):  
Olga Gubar ◽  
Pauline Croisé ◽  
Sergii Kropyvko ◽  
Tetyana Gryaznova ◽  
Petra Tóth ◽  
...  
Keyword(s):  
Membrane Trafficking ◽  
Rho Gtpases ◽  
Rho Gtpase ◽  
Vesicular Trafficking ◽  
Recycling Endosomes ◽  
Vesicle Recycling ◽  
Binding Partners ◽  
Endosomal Recycling ◽  
Early Endosomes ◽  
And Migration

ABSTRACTRho GTPases play a key role in various membrane trafficking processes. RhoU is an atypical small Rho GTPase related to Rac/Cdc42, which possesses unique N- and C-terminal domains that regulate its function and its subcellular localization. RhoU localizes at the plasma membrane, on endosomes and in cell adhesion structures where it governs cell signaling, differentiation and migration. However, despite its endomembrane localization, RhoU function in vesicular trafficking has been unexplored. Here, we identified intersectins (ITSNs) as new binding partners for RhoU and showed that the second PxxP motif at the N terminus of RhoU mediated interactions with the SH3 domains of ITSNs. To evaluate the function of RhoU and ITSNs in vesicular trafficking, we used fluorescent transferrin as a cargo for uptake experiments. We showed that silencing of either RhoU or ITSN2, but not ITSN1, increased transferrin accumulation in early endosomes, resulting from a defect in fast vesicle recycling. Concomitantly, RhoU and ITSN2 colocalized to a subset of Rab4-positive vesicles, suggesting that a RhoU–ITSN2 interaction may occur on fast recycling endosomes to regulate the fate of vesicular cargos.

scholarly journals Live-Cell Imaging in Caenorhabditis elegans Reveals the Distinct Roles of Dynamin Self-Assembly and Guanosine Triphosphate Hydrolysis in the Removal of Apoptotic Cells

2010 ◽  
Vol 21 (4) ◽  
pp. 610-629 ◽  
Author(s):  
Bin He ◽  
Xiaomeng Yu ◽  
Moran Margolis ◽  
Xianghua Liu ◽  
Xiaohong Leng ◽  
...  
Keyword(s):  
Caenorhabditis Elegans ◽  
Membrane Trafficking ◽  
Self Assembly ◽  
Dynamic Control ◽  
The Self ◽  
Apoptotic Cells ◽  
Guanosine Triphosphate ◽  
C Elegans ◽  
Membrane Fission ◽  
Gtp Binding

Dynamins are large GTPases that oligomerize along membranes. Dynamin's membrane fission activity is believed to underlie many of its physiological functions in membrane trafficking. Previously, we reported that DYN-1 ( Caenorhabditis elegans dynamin) drove the engulfment and degradation of apoptotic cells through promoting the recruitment and fusion of intracellular vesicles to phagocytic cups and phagosomes, an activity distinct from dynamin's well-known membrane fission activity. Here, we have detected the oligomerization of DYN-1 in living C. elegans embryos and identified DYN-1 mutations that abolish DYN-1's oligomerization or GTPase activities. Specifically, abolishing self-assembly destroys DYN-1's association with the surfaces of extending pseudopods and maturing phagosomes, whereas inactivating guanosine triphosphate (GTP) binding blocks the dissociation of DYN-1 from these membranes. Abolishing the self-assembly or GTPase activities of DYN-1 leads to common as well as differential phagosomal maturation defects. Whereas both types of mutations cause delays in the transient enrichment of the RAB-5 GTPase to phagosomal surfaces, only the self-assembly mutation but not GTP binding mutation causes failure in recruiting the RAB-7 GTPase to phagosomal surfaces. We propose that during cell corpse removal, dynamin's self-assembly and GTP hydrolysis activities establish a precise dynamic control of DYN-1's transient association to its target membranes and that this control mechanism underlies the dynamic recruitment of downstream effectors to target membranes.

scholarly journals Syndapin/SDPN-1 is required for endocytic recycling and endosomal actin association in the Caenorhabditis elegans intestine

2016 ◽  
Vol 27 (23) ◽  
pp. 3746-3756 ◽  
Author(s):  
Adenrele M. Gleason ◽  
Ken C. Q. Nguyen ◽  
David H. Hall ◽  
Barth D. Grant
Keyword(s):  
Caenorhabditis Elegans ◽  
Membrane Lipids ◽  
Actin Dynamics ◽  
Endocytic Recycling ◽  
Recycling Endosome ◽  
Recycling Endosomes ◽  
Bar Domain ◽  
C Elegans ◽  
Early Endosomes

Syndapin/pascin-family F-BAR domain proteins bind directly to membrane lipids and are associated with actin dynamics at the plasma membrane. Previous reports also implicated mammalian syndapin 2 in endosome function during receptor recycling, but precise analysis of a putative recycling function for syndapin in mammalian systems is difficult because of its effects on the earlier step of endocytic uptake and potential redundancy among the three separate genes that encode mammalian syndapin isoforms. Here we analyze the endocytic transport function of the only Caenorhabditis elegans syndapin, SDPN-1. We find that SDPN-1 is a resident protein of the early and basolateral recycling endosomes in the C. elegans intestinal epithelium, and sdpn-1 deletion mutants display phenotypes indicating a block in basolateral recycling transport. sdpn-1 mutants accumulate abnormal endosomes positive for early endosome and recycling endosome markers that are normally separate, and such endosomes accumulate high levels of basolateral recycling cargo. Furthermore, we observed strong colocalization of endosomal SDPN-1 with the F-actin biosensor Lifeact and found that loss of SDPN-1 greatly reduced Lifeact accumulation on early endosomes. Taken together, our results provide strong evidence for an in vivo function of syndapin in endocytic recycling and suggest that syndapin promotes transport via endosomal fission.

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