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

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.

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Lysosome Biogenesis Mediated by vps-18 Affects Apoptotic Cell Degradation in Caenorhabditis elegans

Molecular Biology of the Cell ◽

10.1091/mbc.e08-04-0441 ◽

2009 ◽

Vol 20 (1) ◽

pp. 21-32 ◽

Cited By ~ 39

Author(s):

Hui Xiao ◽

Didi Chen ◽

Zhou Fang ◽

Jing Xu ◽

Xiaojuan Sun ◽

...

Keyword(s):

Cell Death ◽

Caenorhabditis Elegans ◽

Programmed Cell Death ◽

Direct Evidence ◽

Apoptotic Cell ◽

Apoptotic Cells ◽

Lysosome Biogenesis ◽

Cell Corpse ◽

Lysosomal Protein

Appropriate clearance of apoptotic cells (cell corpses) is an important step of programmed cell death. Although genetic and biochemical studies have identified several genes that regulate the engulfment of cell corpses, how these are degraded after being internalized in engulfing cell remains elusive. Here, we show that VPS-18, the Caenorhabditis elegans homologue of yeast Vps18p, is critical to cell corpse degradation. VPS-18 is expressed and functions in engulfing cells. Deletion of vps-18 leads to significant accumulation of cell corpses that are not degraded properly. Furthermore, vps-18 mutation causes strong defects in the biogenesis of endosomes and lysosomes, thus affecting endosomal/lysosomal protein degradation. Importantly, we demonstrate that phagosomes containing internalized cell corpses are unable to fuse with lysosomes in vps-18 mutants. Our findings thus provide direct evidence for the important role of endosomal/lysosomal degradation in proper clearance of apoptotic cells during programmed cell death.

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

10.1101/2021.07.16.452694 ◽

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.

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

eLife ◽

10.7554/elife.72466 ◽

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

The Journal of Cell Biology ◽

10.1083/jcb.201901074 ◽

2019 ◽

Vol 218 (8) ◽

pp. 2619-2637 ◽

Cited By ~ 3

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.

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

The Journal of Cell Biology ◽

10.1083/jcb.200708130 ◽

2008 ◽

Vol 180 (2) ◽

pp. 357-373 ◽

Cited By ~ 56

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.

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Revisiting the role of microtubules in C. elegans polarity

The Journal of Cell Biology ◽

10.1083/jcb.200710062 ◽

2007 ◽

Vol 179 (3) ◽

pp. 367-369 ◽

Cited By ~ 1

Author(s):

Fumio Motegi ◽

Geraldine Seydoux

Keyword(s):

Caenorhabditis Elegans ◽

Cell Types ◽

Break Symmetry ◽

Severe Loss ◽

C Elegans

Cells must break symmetry to acquire polarity. Microtubules have been implicated in the induction of asymmetry in several cell types, but their role in the Caenorhabditis elegans zygote, a classic polarity model, has remained uncertain. One study (see Tsai and Ahringer on p. 397 of this issue) brings new light to this problem by demonstrating that severe loss of microtubules impairs polarity onset in C. elegans.

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Characterization of Caenorhabditis elegans Homologs of the Down Syndrome Candidate Gene DYRK1A

Genetics ◽

10.1093/genetics/163.2.571 ◽

2003 ◽

Vol 163 (2) ◽

pp. 571-580 ◽

Cited By ~ 1

Author(s):

William B Raich ◽

Celine Moorman ◽

Clay O Lacefield ◽

Jonah Lehrer ◽

Dusan Bartsch ◽

...

Keyword(s):

Down Syndrome ◽

Caenorhabditis Elegans ◽

Trisomy 21 ◽

Gene Dosage ◽

Inducible Promoters ◽

C Elegans ◽

Dual Specificity ◽

Specificity Protein

Abstract The pathology of trisomy 21/Down syndrome includes cognitive and memory deficits. Increased expression of the dual-specificity protein kinase DYRK1A kinase (DYRK1A) appears to play a significant role in the neuropathology of Down syndrome. To shed light on the cellular role of DYRK1A and related genes we identified three DYRK/minibrain-like genes in the genome sequence of Caenorhabditis elegans, termed mbk-1, mbk-2, and hpk-1. We found these genes to be widely expressed and to localize to distinct subcellular compartments. We isolated deletion alleles in all three genes and show that loss of mbk-1, the gene most closely related to DYRK1A, causes no obvious defects, while another gene, mbk-2, is essential for viability. The overexpression of DYRK1A in Down syndrome led us to examine the effects of overexpression of its C. elegans ortholog mbk-1. We found that animals containing additional copies of the mbk-1 gene display behavioral defects in chemotaxis toward volatile chemoattractants and that the extent of these defects correlates with mbk-1 gene dosage. Using tissue-specific and inducible promoters, we show that additional copies of mbk-1 can impair olfaction cell-autonomously in mature, fully differentiated neurons and that this impairment is reversible. Our results suggest that increased gene dosage of human DYRK1A in trisomy 21 may disrupt the function of fully differentiated neurons and that this disruption is reversible.

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A Deficiency Screen for Zygotic Loci Required for Establishment and Patterning of the Epidermis in Caenorhabditis elegans

Genetics ◽

10.1093/genetics/146.1.185 ◽

1997 ◽

Vol 146 (1) ◽

pp. 185-206 ◽

Cited By ~ 1

Author(s):

Rebecca M Terns ◽

Peggy Kroll-Conner ◽

Jiangwen Zhu ◽

Sooyoun Chung ◽

Joel H Rothman

Keyword(s):

Caenorhabditis Elegans ◽

Cell Types ◽

Epidermal Cells ◽

Epidermal Differentiation ◽

Apparent Effect ◽

Internal Organs ◽

C Elegans ◽

Seam Cell ◽

Genomic Regions ◽

Caenorhabditis Elegans Genome

To identify genomic regions required for establishment and patterning of the epidermis, we screened 58 deficiencies that collectively delete at least ∼67% of the Caenorhabditis elegans genome. The epidermal pattern of deficiency homozygous embryos was analyzed by examining expression of a marker specific for one of the three major epidermal cell types, the seam cells. The organization of the epidermis and internal organs was also analyzed using a monoclonal antibody specific for epithelial adherens junctions. While seven deficiencies had no apparent effect on seam cell production, 21 were found to result in subnormal, and five in excess numbers of these cells. An additional 23 deficiencies blocked expression of the seam cell marker, in some cases without preventing cell proliferation. Two deficiencies result in multinucleate seam cells. Deficiencies were also identified that result in subnormal numbers of epidermal cells, hyperfusion of epidermal cells into a large syncytium, or aberrant epidermal differentiation. Finally, analysis of internal epithelia revealed deficiencies that cause defects in formation of internal organs, including circularization of the intestine and bifurcation of the pharynx lumen. This study reveals that many regions of the C. elegans genome are required zygotically for patterning of the epidermis and other epithelia.

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Potential role of protein stabilizers in amelioration of Parkinson's disease and associated effects in transgenic Caenorhabditis elegans model expressing alpha-synuclein

RSC Advances ◽

10.1039/c5ra13546j ◽

2015 ◽

Vol 5 (95) ◽

pp. 77706-77715 ◽

Cited By ~ 4

Author(s):

Supinder Kaur ◽

Aamir Nazir

Keyword(s):

Parkinson’S Disease ◽

Parkinson's Disease ◽

Caenorhabditis Elegans ◽

Potential Role ◽

Alpha Synuclein ◽

C Elegans

Studies employing transgenicC. elegansmodel show that trehalose, a protein stabilizer, alleviates manifestations associated with Parkinson's diseaseviaits inherent activity and through induction of autophagic machinery.

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Three C. elegans Rac proteins and several alternative Rac regulators control axon guidance, cell migration and apoptotic cell phagocytosis

Development ◽

10.1242/dev.128.22.4475 ◽

2001 ◽

Vol 128 (22) ◽

pp. 4475-4488 ◽

Cited By ~ 7

Author(s):

Erik A. Lundquist ◽

Peter W. Reddien ◽

Erika Hartwieg ◽

H. Robert Horvitz ◽

Cornelia I. Bargmann

Keyword(s):

Cell Migration ◽

Axon Guidance ◽

Apoptotic Cell ◽

Regulatory Proteins ◽

Axon Pathfinding ◽

C Elegans ◽

Cell Corpse ◽

And Function ◽

Redundant Functions ◽

Caenorhabditis Elegans Genome

The Caenorhabditis elegans genome contains three rac-like genes, ced-10, mig-2, and rac-2. We report that ced-10, mig-2 and rac-2 act redundantly in axon pathfinding: inactivating one gene had little effect, but inactivating two or more genes perturbed both axon outgrowth and guidance. mig-2 and ced-10 also have redundant functions in some cell migrations. By contrast, ced-10 is uniquely required for cell-corpse phagocytosis, and mig-2 and rac-2 have only subtle roles in this process. Rac activators are also used differentially. The UNC-73 Trio Rac GTP exchange factor affected all Rac pathways in axon pathfinding and cell migration but did not affect cell-corpse phagocytosis. CED-5 DOCK180, which acts with CED-10 Rac in cell-corpse phagocytosis, acted with MIG-2 but not CED-10 in axon pathfinding. Thus, distinct regulatory proteins modulate Rac activation and function in different developmental processes.

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