scholarly journals The small GTPase Rab2 functions in the removal of apoptotic cells in Caenorhabditis elegans

2008 ◽  
Vol 180 (2) ◽  
pp. 357-373 ◽  
Author(s):  
Paolo M. Mangahas ◽  
Xiaomeng Yu ◽  
Kenneth G. Miller ◽  
Zheng Zhou
Keyword(s):  
Caenorhabditis Elegans ◽  
Time Lapse ◽  
Cell Types ◽  
Small Gtpase ◽  
Dominant Negative ◽  
Apoptotic Cells ◽  
Loss Of Function ◽  
Guanosine Triphosphatase ◽  
Cell Corpse ◽  
Different Cell Types

We identify here a novel class of loss-of-function alleles of uncoordinated locomotion(unc)-108, which encodes the Caenorhabditis elegans homologue of the mammalian small guanosine triphosphatase Rab2. Like the previously isolated dominant-negative mutants, unc-108 loss-of-function mutant animals are defective in locomotion. In addition, they display unique defects in the removal of apoptotic cells, revealing a previously uncharacterized function for Rab2. unc-108 acts in neurons and engulfing cells to control locomotion and cell corpse removal, respectively, indicating that unc-108 has distinct functions in different cell types. Using time-lapse microscopy, we find that unc-108 promotes the degradation of engulfed cell corpses. It is required for the efficient recruitment and fusion of lysosomes to phagosomes and the acidification of the phagosomal lumen. In engulfing cells, UNC-108 is enriched on the surface of phagosomes. We propose that UNC-108 acts on phagosomal surfaces to promote phagosome maturation and suggest that mammalian Rab2 may have a similar function in the degradation of apoptotic cells.

scholarly journals The lysosomal cathepsin protease CPL-1 plays a leading role in phagosomal degradation of apoptotic cells in Caenorhabditis elegans

2014 ◽  
Vol 25 (13) ◽  
pp. 2071-2083 ◽  
Author(s):  
Meng Xu ◽  
Yubing Liu ◽  
Liyuan Zhao ◽  
Qiwen Gan ◽  
Xiaochen Wang ◽  
...  
Keyword(s):  
Caenorhabditis Elegans ◽  
Apoptotic Cell ◽  
Cell Types ◽  
Apoptotic Cells ◽  
C Elegans ◽  
Lysosomal Protease ◽  
Leading Role ◽  
Lysosomal Proteases ◽  
Cell Corpse

During programmed cell death, the clearance of apoptotic cells is achieved by their phagocytosis and delivery to lysosomes for destruction in engulfing cells. However, the role of lysosomal proteases in cell corpse destruction is not understood. Here we report the identification of the lysosomal cathepsin CPL-1 as an indispensable protease for apoptotic cell removal in Caenorhabditis elegans. We find that loss of cpl-1 function leads to strong accumulation of germ cell corpses, which results from a failure in degradation rather than engulfment. CPL-1 is expressed in a variety of cell types, including engulfment cells, and its mutation does not affect the maturation of cell corpse–containing phagosomes, including phagosomal recruitment of maturation effectors and phagosome acidification. Of importance, we find that phagosomal recruitment and incorporation of CPL-1 occurs before digestion of cell corpses, which depends on factors required for phagolysosome formation. Using RNA interference, we further examine the role of other candidate lysosomal proteases in cell corpse clearance but find that they do not obviously affect this process. Collectively, these findings establish CPL-1 as the leading lysosomal protease required for elimination of apoptotic cells in C. elegans.

par-4, a gene required for cytoplasmic localization and determination of specific cell types in Caenorhabditis elegans embryogenesis.

Genetics ◽  
1992 ◽  
Vol 130 (4) ◽  
pp. 771-790 ◽  
Author(s):  
D G Morton ◽  
J M Roos ◽  
K J Kemphues
Keyword(s):  
Caenorhabditis Elegans ◽  
Cell Types ◽  
Intestinal Cells ◽  
Specific Cell ◽  
Cytoplasmic Localization ◽  
Loss Of Function ◽  
Embryo Viability ◽  
Cell Stage ◽  
Maternal Genome

Abstract Specification of some cell fates in the early Caenorhabditis elegans embryo is mediated by cytoplasmic localization under control of the maternal genome. Using nine newly isolated mutations, and two existing mutations, we have analyzed the role of the maternally expressed gene par-4 in cytoplasmic localization. We recovered seven new par-4 alleles in screens for maternal effect lethal mutations that result in failure to differentiate intestinal cells. Two additional par-4 mutations were identified in noncomplementation screens using strains with a high frequency of transposon mobility. All 11 mutations cause defects early in development of embryos produced by homozygous mutant mothers. Analysis with a deficiency in the region indicates that it33 is a strong loss-of-function mutation. par-4(it33) terminal stage embryos contain many cells, but show no morphogenesis, and are lacking intestinal cells. Temperature shifts with the it57ts allele suggest that the critical period for both intestinal differentiation and embryo viability begins during oogenesis, about 1.5 hr before fertilization, and ends before the four-cell stage. We propose that the primary function of the par-4 gene is to act as part of a maternally encoded system for cytoplasmic localization in the first cell cycle, with par-4 playing a particularly important role in the determination of intestine. Analysis of a par-4; par-2 double mutant suggests that par-4 and par-2 gene products interact in this system.

scholarly journals Autophagosomes fuse to phagosomes and play important roles in the degradation of apoptotic cells in Caenorhabditis elegans

2021 ◽  
Author(s):  
Omar Pena-Ramos ◽  
Lucia Chiao ◽  
Xianghua Liu ◽  
Tianyou Yao ◽  
Henry He ◽  
...  
Keyword(s):  
Caenorhabditis Elegans ◽  
Small Gtpase ◽  
Apoptotic Cells ◽  
Phagosome Maturation ◽  
Double Membrane ◽  
C Elegans ◽  
Intracellular Organelles ◽  
Intracellular Vesicles ◽  
Cellular Components

Autophagosomes are double-membrane intracellular vesicles that degrade protein aggregates, intracellular organelles, and other cellular components. In the nematode Caenorhabditis elegans, 113 somatic cells undergo apoptosis during embryogenesis and are engulfed and degraded by their neighboring cells. We discovered a novel role of autophagosomes in facilitating the degradation of apoptotic cells in C. elegans embryos using a real-time imaging technique. Specifically, double-membrane autophagosomes in engulfing cells are recruited to the surfaces of phagosomes containing apoptotic cells and subsequently fuse to phagosomes, allowing the inner membrane to enter the phagosomal lumen. Mutants defective in the production of autophagosomes display significant delays in the degradation of apoptotic cells, demonstrating the important contribution of autophagosomes to this process. The signaling pathway led by the phagocytic receptor CED-1, CED-1s adaptor CED-6, and the large GTPase dynamin (DYN-1) promote the recruitment of autophagosomes to phagosomes. Moreover, the subsequent fusion of autophagosomes with phagosomes requires the functions of the small GTPase RAB-7 and the HOPS complex. Our findings reveal that, unlike the single-membrane, LC3- associated phagocytosis (LAP) vesicles reported for mammalian phagocytes, canonical autophagosomes function in the clearance of C. elegans apoptotic cells. These findings add autophagosomes to the collection of intracellular organelles that contribute to phagosome maturation, identify novel crosstalk between the autophagy and phagosome maturation pathways, and discover the upstream factors that initiate this crosstalk.

scholarly journals A nervous system-specific subnuclear organelle in Caenorhabditis elegans

Genetics ◽  
2021 ◽  
Vol 217 (1) ◽  
Author(s):  
Kenneth Pham ◽  
Neda Masoudi ◽  
Eduardo Leyva-Díaz ◽  
Oliver Hobert
Keyword(s):  
Nervous System ◽  
Caenorhabditis Elegans ◽  
Homeobox Gene ◽  
Cell Types ◽  
Nuclear Bodies ◽  
Loss Of Function ◽  
Cell Type ◽  
Cell Type Specificity ◽  
Splicing Speckles ◽  
Polycomb Bodies

Abstract We describe here phase-separated subnuclear organelles in the nematode Caenorhabditis elegans, which we term NUN (NUclear Nervous system-specific) bodies. Unlike other previously described subnuclear organelles, NUN bodies are highly cell type specific. In fully mature animals, 4–10 NUN bodies are observed exclusively in the nucleus of neuronal, glial and neuron-like cells, but not in other somatic cell types. Based on co-localization and genetic loss of function studies, NUN bodies are not related to other previously described subnuclear organelles, such as nucleoli, splicing speckles, paraspeckles, Polycomb bodies, promyelocytic leukemia bodies, gems, stress-induced nuclear bodies, or clastosomes. NUN bodies form immediately after cell cycle exit, before other signs of overt neuronal differentiation and are unaffected by the genetic elimination of transcription factors that control many other aspects of neuronal identity. In one unusual neuron class, the canal-associated neurons, NUN bodies remodel during larval development, and this remodeling depends on the Prd-type homeobox gene ceh-10. In conclusion, we have characterized here a novel subnuclear organelle whose cell type specificity poses the intriguing question of what biochemical process in the nucleus makes all nervous system-associated cells different from cells outside the nervous system.

scholarly journals NUC-1, a Caenorhabditis elegans DNase II homolog, functions in an intermediate step of DNA degradation during apoptosis

2000 ◽  
Vol 14 (5) ◽  
pp. 536-548 ◽  
Author(s):  
Yi-Chun Wu ◽  
Gillian M. Stanfield ◽  
H. Robert Horvitz
Keyword(s):  
Caenorhabditis Elegans ◽  
Intermediate Stage ◽  
Dna Degradation ◽  
Intermediate Step ◽  
Apoptotic Cells ◽  
Chromosomal Dna ◽  
Dnase Ii ◽  
A Cell ◽  
Cell Corpse ◽  
Transient Intermediate

One hallmark of apoptosis is the degradation of chromosomal DNA. We cloned the Caenorhabditis elegans gene nuc-1, which is involved in the degradation of the DNA of apoptotic cells, and found that nuc-1 encodes a homolog of mammalian DNase II. We used the TUNEL technique to assay DNA degradation in nuc-1 and other mutants defective in programmed cell death and discovered that TUNEL labels apoptotic cells only during a transient intermediate stage. Mutations in nuc-1 allowed the generation of TUNEL-reactive DNA but blocked the conversion of TUNEL-reactive DNA to a subsequent TUNEL-unreactive state. Completion of DNA degradation did not occur in the absence of cell-corpse engulfment. Our data suggest that the process of degradation of the DNA of a cell corpse occurs in at least three distinct steps and requires activities provided by both the dying and the engulfing cell.

scholarly journals Caenorhabditis elegans SUR-5, a Novel but Conserved Protein, Negatively Regulates LET-60 Ras Activity during Vulval Induction

1998 ◽  
Vol 18 (8) ◽  
pp. 4556-4564 ◽  
Author(s):  
Trent Gu ◽  
Satoshi Orita ◽  
Min Han
Keyword(s):  
Caenorhabditis Elegans ◽  
Sequence Similarity ◽  
Signal Transduction Pathway ◽  
Specific Aspect ◽  
Dominant Negative ◽  
Loss Of Function ◽  
Negative Function ◽  
Ras Activation ◽  
Dominant Negative Mutations ◽  
Novel Protein

ABSTRACT The let-60 ras gene acts in a signal transduction pathway to control vulval differentiation in Caenorhabditis elegans. By screening suppressors of a dominant negativelet-60 ras allele, we isolated three loss-of-function mutations in the sur-5 gene which appear to act as negative regulators of let-60 ras during vulval induction.sur-5 mutations do not cause an obvious mutant phenotype of their own, and they appear to specifically suppress only one of the two groups of let-60 ras dominant negative mutations, suggesting that the gene may be involved in a specific aspect of Ras activation. Consistent with its negative function, overexpressing sur-5 from an extragenic array partially suppresses the Multivulva phenotype of an activatedlet-60 ras mutation and causes synergistic phenotypes with a lin-45 raf mutation. We have clonedsur-5 and shown that it encodes a novel protein. We have also identified a potential mammalian SUR-5 homolog that is about 35% identical to the worm protein. SUR-5 also has some sequence similarity to acetyl coenzyme A synthetases and is predicted to contain ATP/GTP and AMP binding sites. Our results suggest thatsur-5 gene function may be conserved through evolution.

scholarly journals A Conserved LIM Protein That Affects Muscular Adherens Junction Integrity and Mechanosensory Function in Caenorhabditis elegans

1999 ◽  
Vol 144 (1) ◽  
pp. 45-57 ◽  
Author(s):  
Oliver Hobert ◽  
Donald G. Moerman ◽  
Kathleen A. Clark ◽  
Mary C. Beckerle ◽  
Gary Ruvkun
Keyword(s):  
Caenorhabditis Elegans ◽  
Body Wall ◽  
Structural Integrity ◽  
Adherens Junctions ◽  
Functional Characterization ◽  
Adherens Junction ◽  
Cell Types ◽  
Loss Of Function ◽  
Body Wall Muscles ◽  
Lim Proteins

We describe here the molecular and functional characterization of the Caenorhabditis elegans unc-97 gene, whose gene product constitutes a novel component of muscular adherens junctions. UNC-97 and homologues from several other species define the PINCH family, a family of LIM proteins whose modular composition of five LIM domains implicates them as potential adapter molecules. unc-97 expression is restricted to tissue types that attach to the hypodermis, specifically body wall muscles, vulval muscles, and mechanosensory neurons. In body wall muscles, the UNC-97 protein colocalizes with the β-integrin PAT-3 to the focal adhesion-like attachment sites of muscles. Partial and complete loss-of-function studies demonstrate that UNC-97 affects the structural integrity of the integrin containing muscle adherens junctions and contributes to the mechanosensory functions of touch neurons. The expression of a Drosophila homologue of unc-97 in two integrin containing cell types, muscles, and muscle-attached epidermal cells, suggests that unc-97 function in adherens junction assembly and stability has been conserved across phylogeny. In addition to its localization to adherens junctions UNC-97 can also be detected in the nucleus, suggesting multiple functions for this LIM domain protein.

scholarly journals A Spindle Checkpoint Functions during Mitosis in the Early Caenorhabditis elegans Embryo

2005 ◽  
Vol 16 (3) ◽  
pp. 1056-1070 ◽  
Author(s):  
Sandra E. Encalada ◽  
John Willis ◽  
Rebecca Lyczak ◽  
Bruce Bowerman
Keyword(s):  
Caenorhabditis Elegans ◽  
Chromosome Segregation ◽  
Spindle Checkpoint ◽  
Metaphase Plate ◽  
Time Lapse ◽  
Cell Types ◽  
Embryonic Cells ◽  
Mitotic Spindles ◽  
Animal Cells ◽  
Dividing Cells

During mitosis, chromosome segregation is regulated by a spindle checkpoint mechanism. This checkpoint delays anaphase until all kinetochores are captured by microtubules from both spindle poles, chromosomes congress to the metaphase plate, and the tension between kinetochores and their attached microtubules is properly sensed. Although the spindle checkpoint can be activated in many different cell types, the role of this regulatory mechanism in rapidly dividing embryonic animal cells has remained controversial. Here, using time-lapse imaging of live embryonic cells, we show that chemical or mutational disruption of the mitotic spindle in early Caenorhabditis elegans embryos delays progression through mitosis. By reducing the function of conserved checkpoint genes in mutant embryos with defective mitotic spindles, we show that these delays require the spindle checkpoint. In the absence of a functional checkpoint, more severe defects in chromosome segregation are observed in mutants with abnormal mitotic spindles. We also show that the conserved kinesin CeMCAK, the CENP-F-related proteins HCP-1 and HCP-2, and the core kinetochore protein CeCENP-C all are required for this checkpoint. Our analysis indicates that spindle checkpoint mechanisms are functional in the rapidly dividing cells of an early animal embryo and that this checkpoint can prevent chromosome segregation defects during mitosis.

scholarly journals Efficiency of RNA Interference in the Mouse Hematopoietic System Varies between Cell Types and Developmental Stages

2005 ◽  
Vol 25 (10) ◽  
pp. 3896-3905 ◽  
Author(s):  
Philipp Oberdoerffer ◽  
Chryssa Kanellopoulou ◽  
Vigo Heissmeyer ◽  
Corinna Paeper ◽  
Christine Borowski ◽  
...  
Keyword(s):  
Rna Interference ◽  
Gene Targeting ◽  
Developmental Stages ◽  
Cell Types ◽  
Gene Inactivation ◽  
Loss Of Function ◽  
Homologous Genes ◽  
Family Gene ◽  
Interfering Rna ◽  
Different Cell Types

ABSTRACT RNA interference (RNAi) is a naturally occurring posttranscriptional gene-silencing mechanism that has been adapted as a genetic tool for loss-of-function studies of a variety of organisms. It is more widely applicable than classical gene targeting and allows for the simultaneous inactivation of several homologous genes with a single transgene. Recently, RNAi has been used for conditional and conventional gene inactivation in mice. Unlike gene targeting, RNAi is a dynamic process, and its efficiency may vary both between cell types and throughout development. Here we demonstrate that RNAi can be used to target three separately encoded isoforms of the bcl-2 family gene bfl-1/A1 in a conditional manner in mice. The extent of gene inactivation varies between different cell types and is least efficient in mature lymphocytes. Our data suggest that RNAi is affected by factors beyond small interfering RNA-mRNA stoichiometry.

scholarly journals Autophagosomes fuse to phagosomes and facilitate the degradation of apoptotic cells in Caenorhabditis elegans

eLife ◽  
2022 ◽  
Vol 11 ◽  
Author(s):  
Omar Peña-Ramos ◽  
Lucia Chiao ◽  
Xianghua Liu ◽  
Xiaomeng Yu ◽  
Tianyou Yao ◽  
...  
Keyword(s):  
Caenorhabditis Elegans ◽  
Apoptotic Cell ◽  
Adaptor Protein ◽  
Small Gtpase ◽  
Apoptotic Cells ◽  
Phagosome Maturation ◽  
Double Membrane ◽  
C Elegans ◽  
Intracellular Organelles ◽  
Cellular Components

Autophagosomes are double-membrane intracellular vesicles that degrade protein aggregates, intracellular organelles, and other cellular components. During the development of the nematode Caenorhabditis elegans, many somatic and germ cells undergo apoptosis. These cells are engulfed and degraded by their neighboring cells. We discovered a novel role of autophagosomes in facilitating the degradation of apoptotic cells using a real-time imaging technique. Specifically, the double-membrane autophagosomes in engulfing cells are recruited to the surfaces of phagosomes containing apoptotic cells and subsequently fuse to phagosomes, allowing the inner vesicle to enter the phagosomal lumen. Mutants defective in the production of autophagosomes display significant defects in the degradation of apoptotic cells, demonstrating the importance of autophagosomes to this process. The signaling pathway led by the phagocytic receptor CED-1, the adaptor protein CED-6, and the large GTPase dynamin (DYN-1) promotes the recruitment of autophagosomes to phagosomes. Moreover, the subsequent fusion of autophagosomes with phagosomes requires the functions of the small GTPase RAB-7 and the HOPS complex components. Further observations suggest that autophagosomes provide apoptotic cell-degradation activities in addition to and in parallel of lysosomes. Our findings reveal that, unlike the single-membrane, LC3-associated phagocytosis (LAP) vesicles reported for mammalian phagocytes, the canonical double-membrane autophagosomes facilitate the clearance of C. elegans apoptotic cells. These findings add autophagosomes to the collection of intracellular organelles that contribute to phagosome maturation, identify novel crosstalk between the autophagy and phagosome maturation pathways, and discover the upstream signaling molecules that initiate this crosstalk.

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