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 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 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 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.

scholarly journals The amino acid transporter SLC-36.1 cooperates with PtdIns3P 5-kinase to control phagocytic lysosome reformation

2019 ◽  
Vol 218 (8) ◽  
pp. 2619-2637 ◽  
Author(s):  
Qiwen Gan ◽  
Xin Wang ◽  
Qian Zhang ◽  
Qiuyuan Yin ◽  
Youli Jian ◽  
...  
Keyword(s):  
Amino Acid ◽  
Caenorhabditis Elegans ◽  
Amino Acid Transporter ◽  
Apoptotic Cells ◽  
Phagosome Maturation ◽  
Genetic Pathway ◽  
C Elegans ◽  
Acid Transporter ◽  
Cell Corpse ◽  
Cell Corpse Clearance

Phagocytic removal of apoptotic cells involves formation, maturation, and digestion of cell corpse–containing phagosomes. The retrieval of lysosomal components following phagolysosomal digestion of cell corpses remains poorly understood. Here we reveal that the amino acid transporter SLC-36.1 is essential for lysosome reformation during cell corpse clearance in Caenorhabditis elegans embryos. Loss of slc-36.1 leads to formation of phagolysosomal vacuoles arising from cell corpse–containing phagosomes. In the absence of slc-36.1, phagosome maturation is not affected, but the retrieval of lysosomal components is inhibited. Moreover, loss of PPK-3, the C. elegans homologue of the PtdIns3P 5-kinase PIKfyve, similarly causes accumulation of phagolysosomal vacuoles that are defective in phagocytic lysosome reformation. SLC-36.1 and PPK-3 function in the same genetic pathway, and they directly interact with one another. In addition, loss of slc-36.1 and ppk-3 causes strong defects in autophagic lysosome reformation in adult animals. Our findings thus suggest that the PPK-3–SLC-36.1 axis plays a central role in both phagocytic and autophagic lysosome formation.

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.

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.

A role of SAND-family proteins in endocytosis

2005 ◽  
Vol 33 (4) ◽  
pp. 606-608 ◽  
Author(s):  
D. Poteryaev ◽  
A. Spang
Keyword(s):  
Caenorhabditis Elegans ◽  
Membrane Trafficking ◽  
Reverse Genetics ◽  
Model System ◽  
Loss Of Function ◽  
C Elegans ◽  
Eukaryotic Species ◽  
Multicellular Organisms ◽  
Insight Into

Caenorhabditis elegans has recently been used as an attractive model system to gain insight into mechanisms of endocytosis in multicellular organisms. A combination of forward and reverse genetics has identified a number of new membrane trafficking factors. Most of them have mammalian homologues which function in the same transport events. We describe a novel C. elegans gene sand-1, whose loss of function causes profound endocytic defects in many tissues. SAND-1 belongs to a conserved family of proteins present in all eukaryotic species, whose genome is sequenced. However, SAND family has not been previously characterized in metazoa. Our comparison of C. elegans SAND-1 and its yeast homologue, Mon1p, showed a conserved role of the SAND-family proteins in late steps of endocytic transport.

scholarly journals CAR-1, a Protein That Localizes with the mRNA Decapping Component DCAP-1, Is Required for Cytokinesis and ER Organization in Caenorhabditis elegans Embryos

2006 ◽  
Vol 17 (1) ◽  
pp. 336-344 ◽  
Author(s):  
Jayne M. Squirrell ◽  
Zachary T. Eggers ◽  
Nancy Luedke ◽  
Bonnie Saari ◽  
Andrew Grimson ◽  
...  
Keyword(s):  
Caenorhabditis Elegans ◽  
Membrane Trafficking ◽  
Rna Binding ◽  
Germ Line ◽  
Rna Binding Proteins ◽  
Developmentally Regulated ◽  
Mrna Decapping ◽  
C Elegans ◽  
Cellular Processes ◽  
Spindle Midzone

The division of one cell into two requires the coordination of multiple components. We describe a gene, car-1, whose product may provide a link between disparate cellular processes. Inhibition of car-1 expression in Caenorhabditis elegans embryos causes late cytokinesis failures: cleavage furrows ingress but subsequently regress and the spindle midzone fails to form, even though midzone components are present. The localized accumulation of membrane that normally develops at the apex of the cleavage furrow during the final phase of cytokinesis does not occur and organization of the endoplasmic reticulum is aberrant, indicative of a disruption in membrane trafficking. The car-1 gene has homologues in a number of species, including proteins that associate with RNA binding proteins. CAR-1 localizes to P-granules (germ-line specific ribonucleoprotein particles) and discrete, developmentally regulated cytoplasmic foci. These foci also contain DCAP-1, a protein involved in decapping mRNAs. Thus, CAR-1, a protein likely to be associated with RNA metabolism, plays an essential role in the late stage of cytokinesis, suggesting a novel link between RNA, membrane trafficking and cytokinesis in the C. elegans embryo.

Genetic Analysis of Life-Span in Caenorhabditis elegans

2001 ◽  
Vol 2001 (1) ◽  
Author(s):  
Thomas E. Johnson ◽  
William B. Wood
Keyword(s):  
Caenorhabditis Elegans ◽  
Genetic Analysis ◽  
Life Span ◽  
Recombinant Inbred ◽  
Selective Breeding ◽  
Recombinant Inbred Lines ◽  
Inbred Lines ◽  
The Self ◽  
C Elegans ◽  
Self Fertilization

Crosses between Bristol and Bergerac strains of the self-fertilizing hermaphroditic nematode Caenorhabditis elegans do not show the heterosis effects for life-span that complicate analysis of interstrain crosses with Drosophila or mice. Instead, they yield F l progeny with life-spans similar to those of the parent strains. By analysis of life-span variation among progeny F 2 populations from such crosses and by two independent analyses of life-spans among recombinant inbred lines derived from F 2 individuals by 18 rounds of self-fertilization, we estimate that the heritability of life-span in C. elegans is between 20 and 50%. Recombinant inbred lines show a range in mean life-spans of 10 to 31 days as compared with life-spans of about 18 days for each of the two parental strains. We conclude that life-span variation in C. elegans has a substantial genetic component and that this organism offers promising opportunities for selective breeding of longer-lived strains and genetic analysis of senescence. Reproduced by permission. Thomas E. Johnson, William B. Wood, Genetic Analysis of Life-Span in Caenorhabditis elegans. Proc. Natl. Acad. Sci. U.S.A. 79 , 6603-6607 (1982).

The Nature of Rapidly Extracted Phycocyanin from the Blue-Green Alga Plectonema Boryanum

1971 ◽  
Vol 29 ◽  
pp. 366-367
Author(s):  
M. Kessel ◽  
R. MacColl
Keyword(s):  
Self Assembly ◽  
Analytical Ultracentrifugation ◽  
Uranyl Acetate ◽  
The Self ◽  
Major Protein ◽  
Subunit Structure ◽  
Blue Green Alga ◽  
Thin Sections ◽  
Blue Green Algae ◽  
Cacodylate Buffer

The major protein of the blue-green algae is the biliprotein, C-phycocyanin (Amax = 620 nm), which is presumed to exist in the cell in the form of distinct aggregates called phycobilisomes. The self-assembly of C-phycocyanin from monomer to hexamer has been extensively studied, but the proposed next step in the assembly of a phycobilisome, the formation of 19s subunits, is completely unknown. We have used electron microscopy and analytical ultracentrifugation in combination with a method for rapid and gentle extraction of phycocyanin to study its subunit structure and assembly.To establish the existence of phycobilisomes, cells of P. boryanum in the log phase of growth, growing at a light intensity of 200 foot candles, were fixed in 2% glutaraldehyde in 0.1M cacodylate buffer, pH 7.0, for 3 hours at 4°C. The cells were post-fixed in 1% OsO4 in the same buffer overnight. Material was stained for 1 hour in uranyl acetate (1%), dehydrated and embedded in araldite and examined in thin sections.

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