1
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Jiang Y, Conradt B. A genetic screen identifies C. elegans eif-3.H and hrpr-1 as pro-apoptotic genes and potential activators of egl-1 expression. MICROPUBLICATION BIOLOGY 2024; 2024:10.17912/micropub.biology.001126. [PMID: 38434221 PMCID: PMC10905296 DOI: 10.17912/micropub.biology.001126] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Figures] [Subscribe] [Scholar Register] [Received: 01/15/2024] [Revised: 02/09/2024] [Accepted: 02/14/2024] [Indexed: 03/05/2024]
Abstract
During C. elegans development, 1090 somatic cells are generated of which 131 reproducibly die, many through apoptosis. The C. elegans BH3-only gene egl-1 is the key activator of apoptosis in somatic tissues, and it is predominantly expressed in 'cell death' lineages i.e. lineages in which apoptotic cell death occurs. egl-1 expression is regulated at the transcriptional and post-transcriptional level. For example, we previously showed that the miR-35 and miR-58 families of miRNAs repress egl-1 expression in mothers of 'unwanted' cells by binding to the 3' UTR of egl-1 mRNA, thereby increasing egl-1 mRNA turnover. In a screen for RNA-binding proteins with a role in the post-transcriptional control of egl-1 expression, we identified EIF-3.H (ortholog of human eIF3H) and HRPR-1 (ortholog human hnRNP R/Q) as potential activators of egl-1 expression. In addition, we demonstrate that the knockdown of the eif-3.H or hrpr-1 gene by RNA-mediated interference (RNAi) results in the inappropriate survival of unwanted cells during C. elegans development. Our study provides novel insight into how egl-1 expression is controlled to cause the reproducible pattern of cell death observed during C. elegans development.
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Affiliation(s)
- Yanwen Jiang
- Cell and Developmental Biology, University College London
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2
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Yarychkivska O, Sharmin R, Elkhalil A, Ghose P. Apoptosis and beyond: A new era for programmed cell death in Caenorhabditis elegans. Semin Cell Dev Biol 2024; 154:14-22. [PMID: 36792437 DOI: 10.1016/j.semcdb.2023.02.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2023] [Revised: 01/27/2023] [Accepted: 02/02/2023] [Indexed: 02/16/2023]
Abstract
Programmed cell death (PCD) is crucial for normal development and homeostasis. Our first insights into the genetic regulation of apoptotic cell death came from in vivo studies in the powerful genetic model system of C. elegans. More recently, novel developmental cell death programs occurring both embryonically and post-embryonically, and sex-specifically, have been elucidated. Recent studies in the apoptotic setting have also shed new light on the intricacies of phagocytosis in particular. This review provides a brief historical perspective of the origins of PCD studies in C. elegans, followed by a more detailed description of non-canonical apoptotic and non-apoptotic death programs. We conclude by posing open questions and commenting on our outlook on the future of PCD studies in C. elegans, highlighting the importance of advanced imaging tools and the continued leveraging of C. elegans genetics both with classical and modern cutting-edge approaches.
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Affiliation(s)
| | | | | | - Piya Ghose
- The University of Texas at Arlington, USA.
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3
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Gao Y, Jiao Y, Gong X, Liu J, Xiao H, Zheng Q. Role of transcription factors in apoptotic cells clearance. Front Cell Dev Biol 2023; 11:1110225. [PMID: 36743409 PMCID: PMC9892555 DOI: 10.3389/fcell.2023.1110225] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2022] [Accepted: 01/09/2023] [Indexed: 01/20/2023] Open
Abstract
The human body generates 10-100 billion cells every day, and the same number of cells die to maintain homeostasis. The genetically controlled, autonomously ordered cell death mainly proceeds by apoptosis. Apoptosis is an important way of programmed cell death in multicellular organisms, timely and effective elimination of apoptotic cells plays a key role in the growth and development of organisms and the maintenance of homeostasis. During the clearance of apoptotic cells, transcription factors bind to specific target promoters and act as activators or repressors to regulate multiple genes expression, how transcription factors regulate apoptosis is an important and poorly understood aspect of normal development. This paper summarizes the regulatory mechanisms of transcription factors in the clearance of apoptotic cells to date.
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Affiliation(s)
| | | | | | | | - Hui Xiao
- *Correspondence: Hui Xiao, ; Qian Zheng,
| | - Qian Zheng
- *Correspondence: Hui Xiao, ; Qian Zheng,
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4
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Dube F, Hinas A, Delhomme N, Åbrink M, Svärd S, Tydén E. Transcriptomics of ivermectin response in Caenorhabditis elegans: Integrating abamectin quantitative trait loci and comparison to the Ivermectin-exposed DA1316 strain. PLoS One 2023; 18:e0285262. [PMID: 37141255 PMCID: PMC10159168 DOI: 10.1371/journal.pone.0285262] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Accepted: 04/18/2023] [Indexed: 05/05/2023] Open
Abstract
Parasitic nematodes pose a significant threat to human and animal health, as well as cause economic losses in the agricultural sector. The use of anthelmintic drugs, such as Ivermectin (IVM), to control these parasites has led to widespread drug resistance. Identifying genetic markers of resistance in parasitic nematodes can be challenging, but the free-living nematode Caenorhabditis elegans provides a suitable model. In this study, we aimed to analyze the transcriptomes of adult C. elegans worms of the N2 strain exposed to the anthelmintic drug Ivermectin (IVM), and compare them to those of the resistant strain DA1316 and the recently identified Abamectin Quantitative Trait Loci (QTL) on chromosome V. We exposed pools of 300 adult N2 worms to IVM (10-7 and 10-8 M) for 4 hours at 20°C, extracted total RNA and sequenced it on the Illumina NovaSeq6000 platform. Differentially expressed genes (DEGs) were determined using an in-house pipeline. The DEGs were compared to genes from a previous microarray study on IVM-resistant C. elegans and Abamectin-QTL. Our results revealed 615 DEGs (183 up-regulated and 432 down-regulated genes) from diverse gene families in the N2 C. elegans strain. Of these DEGs, 31 overlapped with genes from IVM-exposed adult worms of the DA1316 strain. We identified 19 genes, including the folate transporter (folt-2) and the transmembrane transporter (T22F3.11), which exhibited an opposite expression in N2 and the DA1316 strain and were deemed potential candidates. Additionally, we compiled a list of potential candidates for further research including T-type calcium channel (cca-1), potassium chloride cotransporter (kcc-2), as well as other genes such as glutamate-gated channel (glc-1) that mapped to the Abamectin-QTL.
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Affiliation(s)
- Faruk Dube
- Department of Biomedical Sciences and Veterinary Public Health, Division of Parasitology, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Andrea Hinas
- Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
| | - Nicolas Delhomme
- Umeå Plant Science Centre (UPSC), Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, Umeå, Sweden
| | - Magnus Åbrink
- Department of Biomedical Sciences and Veterinary Public Health, Section of Immunology, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Staffan Svärd
- Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
| | - Eva Tydén
- Department of Biomedical Sciences and Veterinary Public Health, Division of Parasitology, Swedish University of Agricultural Sciences, Uppsala, Sweden
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5
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Rashid A, Tevlin M, Lu Y, Shaham S. A developmental pathway for epithelial-to-motoneuron transformation in C. elegans. Cell Rep 2022; 40:111414. [PMID: 36170838 PMCID: PMC9579992 DOI: 10.1016/j.celrep.2022.111414] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Revised: 07/18/2022] [Accepted: 09/01/2022] [Indexed: 11/24/2022] Open
Abstract
Motoneurons and motoneuron-like pancreatic β cells arise from radial glia and ductal cells, respectively, both tube-lining progenitors that share molecular regulators. To uncover programs underlying motoneuron formation, we studied a similar, cell-division-independent transformation of the C. elegans tube-lining Y cell into the PDA motoneuron. We find that lin-12/Notch acts through ngn-1/Ngn and its regulator hlh-16/Olig to control transformation timing. lin-12 loss blocks transformation, while lin-12(gf) promotes precocious PDA formation. Early basal expression of ngn-1/Ngn and hlh-16/Olig depends on sem-4/Sall and egl-5/Hox. Later, coincident with Y cell morphological changes, ngn-1/Ngn expression is upregulated in a sem-4/Sall and egl-5/Hox-dependent but hlh-16/Olig-independent manner. Subsequently, Y cell retrograde extension forms an anchored process priming PDA axon extension. Extension requires ngn-1-dependent expression of the cytoskeleton organizers UNC-119, UNC-44/ANK, and UNC-33/CRMP, which also activate PDA terminal-gene expression. Our findings uncover cell-division-independent regulatory events leading to motoneuron generation, suggesting a conserved pathway for epithelial-to-motoneuron/motoneuron-like cell differentiation. Rashid et al. report on a conserved epithelial-to-motoneuron transformation pathway in C. elegans requiring ngn-1/Ngn and hlh-16/Olig. lin-12/Notch regulates transformation timing through these genes, while ngn-1/Ngn and hlh-16/Olig expression levels are regulated by sem-4/Sall and egl-5/Hox. Unexpectedly, the cytoskeleton organizers UNC-119, UNC-44, and UNC-33, which are ngn-1/Ngn targets, promote motoneuron terminal identity.
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Affiliation(s)
- Alina Rashid
- Laboratory of Developmental Genetics, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA
| | - Maya Tevlin
- Laboratory of Developmental Genetics, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA
| | - Yun Lu
- Laboratory of Developmental Genetics, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA
| | - Shai Shaham
- Laboratory of Developmental Genetics, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA.
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6
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Juanez K, Ghose P. Repurposing the Killing Machine: Non-canonical Roles of the Cell Death Apparatus in Caenorhabditis elegans Neurons. Front Cell Dev Biol 2022; 10:825124. [PMID: 35237604 PMCID: PMC8882910 DOI: 10.3389/fcell.2022.825124] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Accepted: 01/31/2022] [Indexed: 12/29/2022] Open
Abstract
Here we highlight the increasingly divergent functions of the Caenorhabditis elegans cell elimination genes in the nervous system, beyond their well-documented roles in cell dismantling and removal. We describe relevant background on the C. elegans nervous system together with the apoptotic cell death and engulfment pathways, highlighting pioneering work in C. elegans. We discuss in detail the unexpected, atypical roles of cell elimination genes in various aspects of neuronal development, response and function. This includes the regulation of cell division, pruning, axon regeneration, and behavioral outputs. We share our outlook on expanding our thinking as to what cell elimination genes can do and noting their versatility. We speculate on the existence of novel genes downstream and upstream of the canonical cell death pathways relevant to neuronal biology. We also propose future directions emphasizing the exploration of the roles of cell death genes in pruning and guidance during embryonic development.
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7
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Jiang HS, Ghose P, Han HF, Wu YZ, Tsai YY, Lin HC, Tseng WC, Wu JC, Shaham S, Wu YC. BLMP-1 promotes developmental cell death in C. elegans by timely repression of ced-9 transcription. Development 2021; 148:dev193995. [PMID: 34541605 PMCID: PMC8572009 DOI: 10.1242/dev.193995] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Accepted: 09/14/2021] [Indexed: 11/20/2022]
Abstract
Programmed cell death (PCD) is a common cell fate in metazoan development. PCD effectors are extensively studied, but how they are temporally regulated is less understood. Here, we report a mechanism controlling tail-spike cell death onset during Caenorhabditis elegans development. We show that the zinc-finger transcription factor BLMP-1, which controls larval development timing, also regulates embryonic tail-spike cell death initiation. BLMP-1 functions upstream of CED-9 and in parallel to DRE-1, another CED-9 and tail-spike cell death regulator. BLMP-1 expression is detected in the tail-spike cell shortly after the cell is born, and blmp-1 mutations promote ced-9-dependent tail-spike cell survival. BLMP-1 binds ced-9 gene regulatory sequences, and inhibits ced-9 transcription just before cell-death onset. BLMP-1 and DRE-1 function together to regulate developmental timing, and their mammalian homologs regulate B-lymphocyte fate. Our results, therefore, identify roles for developmental timing genes in cell-death initiation, and suggest conservation of these functions.
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Affiliation(s)
- Hang-Shiang Jiang
- Institute of Molecular and Cellular Biology, National Taiwan University, Taipei, 106216, Taiwan
| | - Piya Ghose
- Laboratory of Developmental Genetics, The Rockefeller University, New York, NY 10065, USA
- Department of Biology, The University of Texas at Arlington, Arlington, TX 76019, USA
| | - Hsiao-Fen Han
- Institute of Molecular and Cellular Biology, National Taiwan University, Taipei, 106216, Taiwan
| | - Yun-Zhe Wu
- Institute of Molecular and Cellular Biology, National Taiwan University, Taipei, 106216, Taiwan
| | - Ya-Yin Tsai
- Institute of Molecular and Cellular Biology, National Taiwan University, Taipei, 106216, Taiwan
| | - Huang-Chin Lin
- Institute of Molecular and Cellular Biology, National Taiwan University, Taipei, 106216, Taiwan
| | - Wei-Chin Tseng
- Institute of Molecular and Cellular Biology, National Taiwan University, Taipei, 106216, Taiwan
| | - Jui-Ching Wu
- Department of Clinical Laboratory Sciences and Medical Biotechnology, College of Medicine, National Taiwan University, Taipei, 100229, Taiwan
| | - Shai Shaham
- Laboratory of Developmental Genetics, The Rockefeller University, New York, NY 10065, USA
| | - Yi-Chun Wu
- Institute of Molecular and Cellular Biology, National Taiwan University, Taipei, 106216, Taiwan
- Department of Life Science, Center for Systems Biology, and Research Center for Developmental Biology and Regenerative Medicine, National Taiwan University, Taipei, 106216, Taiwan
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, 106216, Taiwan
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8
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Abstract
Cell death is an important facet of animal development. In some developing tissues, death is the ultimate fate of over 80% of generated cells. Although recent studies have delineated a bewildering number of cell death mechanisms, most have only been observed in pathological contexts, and only a small number drive normal development. This Primer outlines the important roles, different types and molecular players regulating developmental cell death, and discusses recent findings with which the field currently grapples. We also clarify terminology, to distinguish between developmental cell death mechanisms, for which there is evidence for evolutionary selection, and cell death that follows genetic, chemical or physical injury. Finally, we suggest how advances in understanding developmental cell death may provide insights into the molecular basis of developmental abnormalities and pathological cell death in disease.
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Affiliation(s)
- Piya Ghose
- Department of Biology, The University of Texas at Arlington, 655 Mitchell St., Arlington, TX 76019, USA
| | - Shai Shaham
- Laboratory of Developmental Genetics, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA
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9
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Ghose P, Rashid A, Insley P, Trivedi M, Shah P, Singhal A, Lu Y, Bao Z, Shaham S. EFF-1 fusogen promotes phagosome sealing during cell process clearance in Caenorhabditis elegans. Nat Cell Biol 2018; 20:393-399. [PMID: 29556089 PMCID: PMC5876135 DOI: 10.1038/s41556-018-0068-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2017] [Accepted: 02/16/2018] [Indexed: 12/21/2022]
Abstract
Phagocytosis of dying cells is critical in development and immunity1–3. While proteins for recognition and engulfment of cellular debris following cell death are known4,5, proteins that directly mediate phagosome sealing are uncharacterized. Furthermore, whether all phagocytic targets are cleared using the same machinery is unclear. Degeneration of morphologically-complex cells, such as neurons, glia, and melanocytes, produces phagocytic targets of various shapes and sizes located in different microenvironments6,7. Such cells, therefore, offer unique settings to explore engulfment program mechanisms and specificity. Here we report that dismantling and clearance of a morphologically-complex C. elegans epithelial cell requires separate cell-soma, proximal-, and distal-process programs. Similar compartment-specific events govern elimination of a C. elegans neuron. While canonical engulfment proteins drive cell-soma clearance, these are not required for process removal. We find that EFF-1, a protein previously implicated in cell-cell fusion8, specifically promotes distal-process phagocytosis. EFF-1 localizes to phagocyte pseudopod tips, and acts exoplasmically to drive phagosome sealing. eff-1 mutations result in phagocytosis arrest with unsealed phagosomes. Our studies suggest universal mechanisms for dismantling morphologically-complex cells, and uncover a phagosome sealing component promoting cell-process clearance.
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Affiliation(s)
- Piya Ghose
- Laboratory of Developmental Genetics, The Rockefeller University, New York, NY, USA
| | - Alina Rashid
- Laboratory of Developmental Genetics, The Rockefeller University, New York, NY, USA
| | - Peter Insley
- Laboratory of Developmental Genetics, The Rockefeller University, New York, NY, USA
| | - Meera Trivedi
- Laboratory of Developmental Genetics, The Rockefeller University, New York, NY, USA
| | - Pavak Shah
- Developmental Biology Program, Sloan Kettering Institute, New York, NY, USA
| | - Anupriya Singhal
- Laboratory of Developmental Genetics, The Rockefeller University, New York, NY, USA
| | - Yun Lu
- Laboratory of Developmental Genetics, The Rockefeller University, New York, NY, USA
| | - Zhirong Bao
- Developmental Biology Program, Sloan Kettering Institute, New York, NY, USA
| | - Shai Shaham
- Laboratory of Developmental Genetics, The Rockefeller University, New York, NY, USA.
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10
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Sarhan M, von Mässenhausen A, Hugo C, Oberbauer R, Linkermann A. Immunological consequences of kidney cell death. Cell Death Dis 2018; 9:114. [PMID: 29371597 PMCID: PMC5833784 DOI: 10.1038/s41419-017-0057-9] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Death of renal cells is central to the pathophysiology of acute tubular necrosis, autoimmunity, necrotizing glomerulonephritis, cystic kidney disease, urosepsis, delayed graft function and transplant rejection. By means of regulated necrosis, immunogenic damage-associated molecular patterns (DAMPs) and highly reactive organelles such as lysosomes, peroxisomes and mitochondria are released from the dying cells, thereby causing an overwhelming immunologic response. The rupture of the plasma membrane exhibits the "point of no return" for the immunogenicity of regulated cell death, explaining why apoptosis, a highly organized cell death subroutine with long-lasting plasma membrane integrity, elicits hardly any immune response. Ferroptosis, an iron-dependent necrotic type cell death, results in the release of DAMPs and large amounts of lipid peroxides. In contrast, anti-inflammatory cytokines are actively released from cells that die by necroptosis, limiting the DAMP-induced immune response to a surrounding microenvironment, whereas at the same time, inflammasome-associated caspases drive maturation of intracellularly expressed interleukin-1β (IL-1β). In a distinct setting, additionally interleukin-18 (IL-18) is expressed during pyroptosis, initiated by gasdermin-mediated plasma membrane rupture. As all of these pathways are druggable, we provide an overview of regulated necrosis in kidney diseases with a focus on immunogenicity and potential therapeutic interventions.
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Affiliation(s)
- Maysa Sarhan
- Division of Nephrology and Dialysis, Department of Medicine III, Medical University Vienna, Vienna, Austria
| | - Anne von Mässenhausen
- Division of Nephrology, Department of Internal Medicine III, University Hospital Carl Gustav Carus at the Technische Universität Dresden, Dresden, Germany
| | - Christian Hugo
- Division of Nephrology, Department of Internal Medicine III, University Hospital Carl Gustav Carus at the Technische Universität Dresden, Dresden, Germany
| | - Rainer Oberbauer
- Division of Nephrology and Dialysis, Department of Medicine III, Medical University Vienna, Vienna, Austria
| | - Andreas Linkermann
- Division of Nephrology, Department of Internal Medicine III, University Hospital Carl Gustav Carus at the Technische Universität Dresden, Dresden, Germany.
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11
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Aram L, Yacobi-Sharon K, Arama E. CDPs: caspase-dependent non-lethal cellular processes. Cell Death Differ 2017; 24:1307-1310. [PMID: 28695898 PMCID: PMC5520448 DOI: 10.1038/cdd.2017.111] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Affiliation(s)
- Lior Aram
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Keren Yacobi-Sharon
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Eli Arama
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
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12
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Subasic D, Stoeger T, Eisenring S, Matia-González AM, Imig J, Zheng X, Xiong L, Gisler P, Eberhard R, Holtackers R, Gerber AP, Pelkmans L, Hengartner MO. Post-transcriptional control of executioner caspases by RNA-binding proteins. Genes Dev 2017; 30:2213-2225. [PMID: 27798844 PMCID: PMC5088569 DOI: 10.1101/gad.285726.116] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2016] [Accepted: 09/16/2016] [Indexed: 12/03/2022]
Abstract
In this study, Subasic et al. investigated the post-transcriptional control of caspases. The authors describe four conserved RNA-binding proteins (RBPs) that sequentially repress the CED-3 caspase in distinct regions of the C. elegans germline and identify seven RBPs that regulate human caspase-3 expression and/or activation, suggesting that translational inhibition of executioner caspases by RBPs might be a general strategy used widely across the animal kingdom to control apoptosis. Caspases are key components of apoptotic pathways. Regulation of caspases occurs at several levels, including transcription, proteolytic processing, inhibition of enzymatic function, and protein degradation. In contrast, little is known about the extent of post-transcriptional control of caspases. Here, we describe four conserved RNA-binding proteins (RBPs)—PUF-8, MEX-3, GLD-1, and CGH-1—that sequentially repress the CED-3 caspase in distinct regions of the Caenorhabditis elegans germline. We demonstrate that GLD-1 represses ced-3 mRNA translation via two binding sites in its 3′ untranslated region (UTR), thereby ensuring a dual control of unwanted cell death: at the level of p53/CEP-1 and at the executioner caspase level. Moreover, we identified seven RBPs that regulate human caspase-3 expression and/or activation, including human PUF-8, GLD-1, and CGH-1 homologs PUM1, QKI, and DDX6. Given the presence of unusually long executioner caspase 3′ UTRs in many metazoans, translational control of executioner caspases by RBPs might be a strategy used widely across the animal kingdom to control apoptosis.
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Affiliation(s)
- Deni Subasic
- Institute of Molecular Life Sciences, University of Zurich, 8057 Zurich, Switzerland.,Molecular Life Sciences PhD Program, Swiss Federal Institute of Technology, University of Zurich, 8057 Zurich, Switzerland
| | - Thomas Stoeger
- Institute of Molecular Life Sciences, University of Zurich, 8057 Zurich, Switzerland.,Systems Biology PhD Program, Swiss Federal Institute of Technology, University of Zurich, 8057 Zurich, Switzerland
| | - Seline Eisenring
- Institute of Molecular Life Sciences, University of Zurich, 8057 Zurich, Switzerland
| | - Ana M Matia-González
- Faculty of Health and Medical Sciences, Department of Microbial and Cellular Sciences, University of Surrey, Stag Hill Campus, GU2 7XH Guildford, United Kingdom
| | - Jochen Imig
- Institute of Pharmaceutical Sciences, Swiss Federal Institute of Technology, 8093 Zurich, Switzerland
| | - Xue Zheng
- Institute of Molecular Life Sciences, University of Zurich, 8057 Zurich, Switzerland
| | - Lei Xiong
- Institute of Molecular Life Sciences, University of Zurich, 8057 Zurich, Switzerland
| | - Pascal Gisler
- Institute of Molecular Life Sciences, University of Zurich, 8057 Zurich, Switzerland
| | - Ralf Eberhard
- Institute of Molecular Life Sciences, University of Zurich, 8057 Zurich, Switzerland
| | - René Holtackers
- Institute of Molecular Life Sciences, University of Zurich, 8057 Zurich, Switzerland
| | - André P Gerber
- Faculty of Health and Medical Sciences, Department of Microbial and Cellular Sciences, University of Surrey, Stag Hill Campus, GU2 7XH Guildford, United Kingdom
| | - Lucas Pelkmans
- Institute of Molecular Life Sciences, University of Zurich, 8057 Zurich, Switzerland
| | - Michael O Hengartner
- Institute of Molecular Life Sciences, University of Zurich, 8057 Zurich, Switzerland
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13
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Programmed Cell Death During Caenorhabditis elegans Development. Genetics 2017; 203:1533-62. [PMID: 27516615 DOI: 10.1534/genetics.115.186247] [Citation(s) in RCA: 66] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2016] [Accepted: 04/22/2016] [Indexed: 12/21/2022] Open
Abstract
Programmed cell death is an integral component of Caenorhabditis elegans development. Genetic and reverse genetic studies in C. elegans have led to the identification of many genes and conserved cell death pathways that are important for the specification of which cells should live or die, the activation of the suicide program, and the dismantling and removal of dying cells. Molecular, cell biological, and biochemical studies have revealed the underlying mechanisms that control these three phases of programmed cell death. In particular, the interplay of transcriptional regulatory cascades and networks involving multiple transcriptional regulators is crucial in activating the expression of the key death-inducing gene egl-1 and, in some cases, the ced-3 gene in cells destined to die. A protein interaction cascade involving EGL-1, CED-9, CED-4, and CED-3 results in the activation of the key cell death protease CED-3, which is tightly controlled by multiple positive and negative regulators. The activation of the CED-3 caspase then initiates the cell disassembly process by cleaving and activating or inactivating crucial CED-3 substrates; leading to activation of multiple cell death execution events, including nuclear DNA fragmentation, mitochondrial elimination, phosphatidylserine externalization, inactivation of survival signals, and clearance of apoptotic cells. Further studies of programmed cell death in C. elegans will continue to advance our understanding of how programmed cell death is regulated, activated, and executed in general.
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14
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Schwendeman AR, Shaham S. A High-Throughput Small Molecule Screen for C. elegans Linker Cell Death Inhibitors. PLoS One 2016; 11:e0164595. [PMID: 27716809 PMCID: PMC5055323 DOI: 10.1371/journal.pone.0164595] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Accepted: 09/27/2016] [Indexed: 12/29/2022] Open
Abstract
Programmed cell death is a ubiquitous process in metazoan development. Apoptosis, one cell death form, has been studied extensively. However, mutations inactivating key mammalian apoptosis regulators do not block most developmental cell culling, suggesting that other cell death pathways are likely important. Recent work in the nematode Caenorhabditis elegans identified a non-apoptotic cell death form mediating the demise of the male-specific linker cell. This cell death process (LCD, linker cell-type death) is morphologically conserved, and its molecular effectors also mediate axon degeneration in mammals and Drosophila. To develop reagents to manipulate LCD, we established a simple high-throughput screening protocol for interrogating the effects of small molecules on C. elegans linker cell death in vivo. From 23,797 compounds assayed, 11 reproducibly block linker cell death onset. Of these, five induce animal lethality, and six promote a reversible developmental delay. These results provide proof-of principle validation of our screening protocol, demonstrate that developmental progression is required for linker cell death, and suggest that larger scale screens may identify LCD-specific small-molecule regulators that target the LCD execution machinery.
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Affiliation(s)
- Andrew R. Schwendeman
- Laboratory of Developmental Genetics, The Rockefeller University, New York, New York, United States of America
| | - Shai Shaham
- Laboratory of Developmental Genetics, The Rockefeller University, New York, New York, United States of America
- * E-mail:
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Wang X, Yang C. Programmed cell death and clearance of cell corpses in Caenorhabditis elegans. Cell Mol Life Sci 2016; 73:2221-36. [PMID: 27048817 PMCID: PMC11108496 DOI: 10.1007/s00018-016-2196-z] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Accepted: 03/18/2016] [Indexed: 01/01/2023]
Abstract
Programmed cell death is critical to the development of diverse animal species from C. elegans to humans. In C. elegans, the cell death program has three genetically distinguishable phases. During the cell suicide phase, the core cell death machinery is activated through a protein interaction cascade. This activates the caspase CED-3, which promotes numerous pro-apoptotic activities including DNA degradation and exposure of the phosphatidylserine "eat me" signal on the cell corpse surface. Specification of the cell death fate involves transcriptional activation of the cell death initiator EGL-1 or the caspase CED-3 by coordinated actions of specific transcription factors in distinct cell types. In the cell corpse clearance stage, recognition of cell corpses by phagocytes triggers several signaling pathways to induce phagocytosis of apoptotic cell corpses. Cell corpse-enclosing phagosomes ultimately fuse with lysosomes for digestion of phagosomal contents. This article summarizes our current knowledge about programmed cell death and clearance of cell corpses in C. elegans.
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Affiliation(s)
- Xiaochen Wang
- National Institute of Biological Sciences, No. 7 Science Park Road, Zhongguancun Life Science Park, Beijing, 102206, China.
| | - Chonglin Yang
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, No. 1 West Beichen Road, Chaoyang District, Beijing, 100101, China.
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Kinet MJ, Malin JA, Abraham MC, Blum ES, Silverman MR, Lu Y, Shaham S. HSF-1 activates the ubiquitin proteasome system to promote non-apoptotic developmental cell death in C. elegans. eLife 2016; 5. [PMID: 26952214 PMCID: PMC4821803 DOI: 10.7554/elife.12821] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2015] [Accepted: 03/07/2016] [Indexed: 01/18/2023] Open
Abstract
Apoptosis is a prominent metazoan cell death form. Yet, mutations in apoptosis
regulators cause only minor defects in vertebrate development, suggesting that
another developmental cell death mechanism exists. While some non-apoptotic programs
have been molecularly characterized, none appear to control developmental cell
culling. Linker-cell-type death (LCD) is a morphologically conserved non-apoptotic
cell death process operating in Caenorhabditis elegans and
vertebrate development, and is therefore a compelling candidate process complementing
apoptosis. However, the details of LCD execution are not known. Here we delineate a
molecular-genetic pathway governing LCD in C. elegans. Redundant
activities of antagonistic Wnt signals, a temporal control pathway, and
mitogen-activated protein kinase kinase signaling control heat shock factor 1
(HSF-1), a conserved stress-activated transcription factor. Rather than protecting
cells, HSF-1 promotes their demise by activating components of the ubiquitin
proteasome system, including the E2 ligase LET-70/UBE2D2 functioning with E3
components CUL-3, RBX-1, BTBD-2, and SIAH-1. Our studies uncover design similarities
between LCD and developmental apoptosis, and provide testable predictions for
analyzing LCD in vertebrates. DOI:http://dx.doi.org/10.7554/eLife.12821.001 Embryos make numerous new cells as they develop, but also destroy many cells to
remove the faulty ones and to ensure that tissues grow to the right size and shape.
This deliberate form of cell death must be precisely regulated to prevent too many
cells or healthy cells, from being destroyed. Understanding the molecular mechanisms
that govern cell death is therefore important for understanding normal development
and also human disease. One well-studied process that leads to cell death is called apoptosis. This process
carefully dismantles and breaks down the components of a cell, but does not seem to
account for all cell death that occurs during animal development. Recently another
developmental cell-death pathway, called the linker-cell-type death, was discovered
in a small roundworm called Caenorhabditis elegans. This pathway
appears to work in mammalian cells as well, and may help to break down nerve fibers
that are not needed. However, many of this pathway’s component parts remained
unknown. Kinet, Malin et al. have now used a combination of genetics and cell biology in
C. elegans to uncover the components of linker-cell-type death
and to investigate how they interact. The results of these studies revealed a
hierarchy of genetic interactions that governs this pathway in C.
elegans. One protein called HSF-1 plays a particularly important role.
This protein is a transcription factor and it binds to, and regulates, the activities
of various genes. HSF-1 usually works in cells to protect them from stress, but
Kinet, Malin et al. showed that it instead promotes linker-cell-type death by
activating a molecular machine, called the proteasome, that breaks down proteins. The
experiments also revealed two proteins (called BTBD-2 and SIAH-1) that may be
important for shuttling specific proteins for degradation by the proteasome. Three signalling pathways that regulate important developmental processes also
regulate the activation of linker-cell-type death. Kinet, Malin et al. propose that
these signalling pathways do so by working together to activate HSF-1, which in turn
activates the genes that lead to the destruction of cells by the proteasome. A future challenge is to understand in more detail how the more recently discovered
cell death pathway actually kills cells. Further work could also explore how HSF-1, a
protein that normally protects cells, is transformed into a cell-killing protein. DOI:http://dx.doi.org/10.7554/eLife.12821.002
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Affiliation(s)
- Maxime J Kinet
- Laboratory of Developmental Genetics, The Rockefeller University, New York, United States
| | - Jennifer A Malin
- Laboratory of Developmental Genetics, The Rockefeller University, New York, United States
| | - Mary C Abraham
- Laboratory of Developmental Genetics, The Rockefeller University, New York, United States
| | - Elyse S Blum
- Laboratory of Developmental Genetics, The Rockefeller University, New York, United States
| | - Melanie R Silverman
- Laboratory of Developmental Genetics, The Rockefeller University, New York, United States
| | - Yun Lu
- Laboratory of Developmental Genetics, The Rockefeller University, New York, United States
| | - Shai Shaham
- Laboratory of Developmental Genetics, The Rockefeller University, New York, United States
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Abstract
Cell death is a common and important feature of animal development, and cell death defects underlie many human disease states. The nematode Caenorhabditis elegans has proven fertile ground for uncovering molecular and cellular processes controlling programmed cell death. A core pathway consisting of the conserved proteins EGL-1/BH3-only, CED-9/BCL2, CED-4/APAF1, and CED-3/caspase promotes most cell death in the nematode, and a conserved set of proteins ensures the engulfment and degradation of dying cells. Multiple regulatory pathways control cell death onset in C. elegans, and many reveal similarities with tumor formation pathways in mammals, supporting the idea that cell death plays key roles in malignant progression. Nonetheless, a number of observations suggest that our understanding of developmental cell death in C. elegans is incomplete. The interaction between dying and engulfing cells seems to be more complex than originally appreciated, and it appears that key aspects of cell death initiation are not fully understood. It has also become apparent that the conserved apoptotic pathway is dispensable for the demise of the C. elegans linker cell, leading to the discovery of a previously unexplored gene program promoting cell death. Here, we review studies that formed the foundation of cell death research in C. elegans and describe new observations that expand, and in some cases remodel, this edifice. We raise the possibility that, in some cells, more than one death program may be needed to ensure cell death fidelity.
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Affiliation(s)
| | - Shai Shaham
- Laboratory of Developmental Genetics, The Rockefeller University, New York, USA.
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Tower J. Programmed cell death in aging. Ageing Res Rev 2015; 23:90-100. [PMID: 25862945 DOI: 10.1016/j.arr.2015.04.002] [Citation(s) in RCA: 247] [Impact Index Per Article: 27.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2014] [Revised: 03/15/2015] [Accepted: 04/01/2015] [Indexed: 02/08/2023]
Abstract
Programmed cell death (PCD) pathways, including apoptosis and regulated necrosis, are required for normal cell turnover and tissue homeostasis. Mis-regulation of PCD is increasingly implicated in aging and aging-related disease. During aging the cell turnover rate declines for several highly-mitotic tissues. Aging-associated disruptions in systemic and inter-cell signaling combined with cell-autonomous damage and mitochondrial malfunction result in increased PCD in some cell types, and decreased PCD in other cell types. Increased PCD during aging is implicated in immune system decline, skeletal muscle wasting (sarcopenia), loss of cells in the heart, and neurodegenerative disease. In contrast, cancer cells and senescent cells are resistant to PCD, enabling them to increase in abundance during aging. PCD pathways limit life span in fungi, but whether PCD pathways normally limit adult metazoan life span is not yet clear. PCD is regulated by a balance of negative and positive factors, including the mitochondria, which are particularly subject to aging-associated malfunction.
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Wang J, Chitturi J, Ge Q, Laskova V, Wang W, Li X, Ding M, Zhen M, Huang X. The C. elegans COE transcription factor UNC-3 activates lineage-specific apoptosis and affects neurite growth in the RID lineage. Development 2015; 142:1447-57. [PMID: 25790851 DOI: 10.1242/dev.119479] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2014] [Accepted: 02/17/2015] [Indexed: 12/23/2022]
Abstract
Mechanisms that regulate apoptosis in a temporal and lineage-specific manner remain poorly understood. The COE (Collier/Olf/EBF) transcription factors have been implicated in the development of many cell types, including neurons. Here, we show that the sole Caenorhabditis elegans COE protein, UNC-3, together with a histone acetyltransferase, CBP-1/P300, specifies lineage-specific apoptosis and certain aspects of neurite trajectory. During embryogenesis, the RID progenitor cell gives rise to the RID neuron and RID sister cell; the latter undergoes apoptosis shortly after cell division upon expression of the pro-apoptotic gene egl-1. We observe UNC-3 expression in the RID progenitor, and the absence of UNC-3 results in the failure of the RID lineage to express a Pegl-1::GFP reporter and in the survival of the RID sister cell. Lastly, UNC-3 interacts with CBP-1, and cbp-1 mutants exhibit a similar RID phenotype to unc-3. Thus, in addition to playing a role in neuronal terminal differentiation, UNC-3 is a cell lineage-specific regulator of apoptosis.
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Affiliation(s)
- Jinbo Wang
- State Key Laboratory of Molecular and Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jyothsna Chitturi
- Lunenfeld and Tanebaum Research Institute, University of Toronto, Toronto, Ontario, Canada M5G 1X5
| | - Qinglan Ge
- State Key Laboratory of Molecular and Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China University of Chinese Academy of Sciences, Beijing 100049, China
| | - Valeriya Laskova
- Lunenfeld and Tanebaum Research Institute, University of Toronto, Toronto, Ontario, Canada M5G 1X5
| | - Wei Wang
- State Key Laboratory of Molecular and Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
| | - Xia Li
- State Key Laboratory of Molecular and Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
| | - Mei Ding
- State Key Laboratory of Molecular and Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
| | - Mei Zhen
- Lunenfeld and Tanebaum Research Institute, University of Toronto, Toronto, Ontario, Canada M5G 1X5
| | - Xun Huang
- State Key Laboratory of Molecular and Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
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20
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The translational regulators GCN-1 and ABCF-3 act together to promote apoptosis in C. elegans. PLoS Genet 2014; 10:e1004512. [PMID: 25101958 PMCID: PMC4125083 DOI: 10.1371/journal.pgen.1004512] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2013] [Accepted: 05/31/2014] [Indexed: 12/04/2022] Open
Abstract
The proper regulation of apoptosis requires precise spatial and temporal control of gene expression. While the transcriptional and translational activation of pro-apoptotic genes is known to be crucial to triggering apoptosis, how different mechanisms cooperate to drive apoptosis is largely unexplored. Here we report that pro-apoptotic transcriptional and translational regulators act in distinct pathways to promote programmed cell death. We show that the evolutionarily conserved C. elegans translational regulators GCN-1 and ABCF-3 contribute to promoting the deaths of most somatic cells during development. GCN-1 and ABCF-3 are not obviously involved in the physiological germ-cell deaths that occur during oocyte maturation. By striking contrast, these proteins play an essential role in the deaths of germ cells in response to ionizing irradiation. GCN-1 and ABCF-3 are similarly co-expressed in many somatic and germ cells and physically interact in vivo, suggesting that GCN-1 and ABCF-3 function as members of a protein complex. GCN-1 and ABCF-3 are required for the basal level of phosphorylation of eukaryotic initiation factor 2α (eIF2α), an evolutionarily conserved regulator of mRNA translation. The S. cerevisiae homologs of GCN-1 and ABCF-3, which are known to control eIF2α phosphorylation, can substitute for the worm proteins in promoting somatic cell deaths in C. elegans. We conclude that GCN-1 and ABCF-3 likely control translational initiation in C. elegans. GCN-1 and ABCF-3 act independently of the anti-apoptotic BCL-2 homolog CED-9 and of transcriptional regulators that upregulate the pro-apoptotic BH3-only gene egl-1. Our results suggest that GCN-1 and ABCF-3 function in a pathway distinct from the canonical CED-9-regulated cell-death execution pathway. We propose that the translational regulators GCN-1 and ABCF-3 maternally contribute to general apoptosis in C. elegans via a novel pathway and that the function of GCN-1 and ABCF-3 in apoptosis might be evolutionarily conserved. Apoptosis, also referred to as programmed cell death, is a crucial cellular process that eliminates unwanted cells during animal development and tissue homeostasis. Abnormal regulation of apoptosis can cause developmental defects and a variety of other human disorders, including cancer, neurodegenerative diseases and autoimmune diseases. Therefore, it is important to identify regulatory mechanisms that control apoptosis. Previous studies have demonstrated that the transcriptional induction of apoptotic genes can be crucial to initiating an apoptotic program. Less is known about translational controls of apoptosis. Here we report that the evolutionarily conserved C. elegans translational regulators GCN-1 and ABCF-3 promote apoptosis generally and act independently of the anti-apoptotic BCL-2 homolog CED-9. GCN-1 and ABCF-3 physically interact and maintain the phosphorylation level of eukaryotic initiation factor 2α, suggesting that GCN-1 and ABCF-3 act together to regulate the initiation of translation. We propose that the translational regulators GCN-1 and ABCF-3 maternally contribute to the proper execution of the apoptotic program.
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Abstract
The nematode Caenorhabditis elegans has served as a fruitful setting for cell death research for over three decades. A conserved pathway of four genes, egl-1/BH3-only, ced-9/Bcl-2, ced-4/Apaf-1, and ced-3/caspase, coordinates most developmental cell deaths in C. elegans. However, other cell death forms, programmed and pathological, have also been described in this animal. Some of these share morphological and/or molecular similarities with the canonical apoptotic pathway, while others do not. Indeed, recent studies suggest the existence of an entirely novel mode of programmed developmental cell destruction that may also be conserved beyond nematodes. Here, we review evidence for these noncanonical pathways. We propose that different cell death modalities can function as backup mechanisms for apoptosis, or as tailor-made programs that allow specific dying cells to be efficiently cleared from the animal.
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Affiliation(s)
- Maxime J Kinet
- Laboratory of Developmental Genetics, The Rockefeller University, New York, USA
| | - Shai Shaham
- Laboratory of Developmental Genetics, The Rockefeller University, New York, USA.
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22
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Related F-box proteins control cell death in Caenorhabditis elegans and human lymphoma. Proc Natl Acad Sci U S A 2013; 110:3943-8. [PMID: 23431138 DOI: 10.1073/pnas.1217271110] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Cell death is a common metazoan cell fate, and its inactivation is central to human malignancy. In Caenorhabditis elegans, apoptotic cell death occurs via the activation of the caspase CED-3 following binding of the EGL-1/BH3-only protein to the antiapoptotic CED-9/BCL2 protein. Here we report a major alternative mechanism for caspase activation in vivo involving the F-box protein DRE-1. DRE-1 functions in parallel to EGL-1, requires CED-9 for activity, and binds to CED-9, suggesting that DRE-1 promotes apoptosis by inactivating CED-9. FBXO10, a human protein related to DRE-1, binds BCL2 and promotes its degradation, thereby initiating cell death. Moreover, some human diffuse large B-cell lymphomas have inactivating mutations in FBXO10 or express FBXO10 at low levels. Our results suggest that DRE-1/FBXO10 is a conserved regulator of apoptosis.
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23
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Chisholm AD, Xu S. The Caenorhabditis elegans epidermis as a model skin. II: differentiation and physiological roles. WILEY INTERDISCIPLINARY REVIEWS-DEVELOPMENTAL BIOLOGY 2012; 1:879-902. [PMID: 23539358 DOI: 10.1002/wdev.77] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The Caenorhabditis elegans epidermis forms one of the principal barrier epithelia of the animal. Differentiation of the epidermis begins in mid embryogenesis and involves apical-basal polarization of the cytoskeletal and secretory systems as well as cellular junction formation. Secretion of the external cuticle layers is one of the major developmental and physiological specializations of the epidermal epithelium. The four post-embryonic larval stages are separated by periodic moults, in which the epidermis generates a new cuticle with stage-specific characteristics. The differentiated epidermis also plays key roles in endocrine signaling, fat storage, and ionic homeostasis. The epidermis is intimately associated with the development and function of the nervous system, and may have glial-like roles in modulating neuronal function. The epidermis provides passive and active defenses against skin-penetrating pathogens and can repair small wounds. Finally, age-dependent deterioration of the epidermis is a prominent feature of aging and may affect organismal aging and lifespan.
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Affiliation(s)
- Andrew D Chisholm
- Division of Biological Sciences, Section of Cell and Developmental Biology, University of California San Diego, La Jolla, CA, USA.
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Florentin A, Arama E. Caspase levels and execution efficiencies determine the apoptotic potential of the cell. ACTA ACUST UNITED AC 2012; 196:513-27. [PMID: 22351928 PMCID: PMC3283987 DOI: 10.1083/jcb.201107133] [Citation(s) in RCA: 101] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Differences in expression level of the effector caspases Drice and Dcp-1 and in their intrinsic abilities to induce apoptosis and to control the rate of cell death underlie the differential sensitivities of cells to apoptosis. Essentially, all metazoan cells can undergo apoptosis, but some cells are more sensitive than others to apoptotic stimuli. To date, it is unclear what determines the apoptotic potential of the cell. We set up an in vivo system for monitoring and comparing the activity levels of the two main effector caspases in Drosophila melanogaster, Drice and Dcp-1. Both caspases were activated by the apoptosome after irradiation. However, whereas each caspase alone could induce apoptosis, Drice was a more effective inducer of apoptosis than Dcp-1, which instead had a role in establishing the rate of cell death. These functional differences are attributed to their intrinsic properties rather than merely their tissue specificities. Significantly, the levels of the procaspases are directly proportional to their activity levels and play a key role in determining the cell’s sensitivity to apoptosis. Finally, we provide evidence for the existence of a cellular execution threshold of caspase activity, which must be reached to induce apoptosis.
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Affiliation(s)
- Anat Florentin
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
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25
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Abstract
Cancer is a complex disease in which cells have circumvented normal restraints on tissue growth and have acquired complex abnormalities in their genomes, posing a considerable challenge to identifying the pathways and mechanisms that drive fundamental aspects of the malignant phenotype. Genetic analyses of the normal development of the nematode Caenorhabditis elegans have revealed evolutionarily conserved mechanisms through which individual cells establish their fates, and how they make and execute the decision to survive or undergo programmed cell death. The pathways identified through these studies have mammalian counterparts that are co-opted by malignant cells. Effective cancer drugs now target some of these pathways, and more are likely to be discovered.
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Affiliation(s)
- Malia B Potts
- Departments of Pediatrics and Molecular Biology, University of Texas Southwestern Medical Center at Dallas, 75390-9148, USA
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26
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Six and Eya promote apoptosis through direct transcriptional activation of the proapoptotic BH3-only gene egl-1 in Caenorhabditis elegans. Proc Natl Acad Sci U S A 2010; 107:15479-84. [PMID: 20713707 DOI: 10.1073/pnas.1010023107] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The decision of a cell to undergo programmed cell death is tightly regulated during animal development and tissue homeostasis. Here, we show that the Caenorhabditis elegans Six family homeodomain protein C. elegans homeobox (CEH-34) and the Eyes absent ortholog EYA-1 promote the programmed cell death of a specific pharyngeal neuron, the sister of the M4 motor neuron. Loss of either ceh-34 or eya-1 function causes survival of the M4 sister cell, which normally undergoes programmed cell death. CEH-34 physically interacts with the conserved EYA domain of EYA-1 in vitro. We identify an egl-1 5' cis-regulatory element that controls the programmed cell death of the M4 sister cell and show that CEH-34 binds directly to this site. Expression of the proapoptotic gene egl-1 in the M4 sister cell requires ceh-34 and eya-1 function. We conclude that an evolutionarily conserved complex that includes CEH-34 and EYA-1 directly activates egl-1 expression through a 5' cis-regulatory element to promote the programmed cell death of the M4 sister cell. We suggest that the regulation of apoptosis by Six and Eya family members is conserved in mammals and involved in human diseases caused by mutations in Six and Eya.
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27
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Transcriptional upregulation of both egl-1 BH3-only and ced-3 caspase is required for the death of the male-specific CEM neurons. Cell Death Differ 2010; 17:1266-76. [PMID: 20150917 PMCID: PMC2902690 DOI: 10.1038/cdd.2010.3] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Most of the 131 cells that die during the development of a C. elegans hermaphrodite do so ~30 min after being generated. Furthermore, in these cells, the pro-caspase proCED-3 is inherited from progenitors and the transcriptional upregulation of the BH3-only gene egl-1 is thought to be sufficient for apoptosis induction. In contrast, the four CEM neurons, which die in hermaphrodites, but not males, die ~150 min after being generated. We found that in the CEMs, the transcriptional activation of both the egl-1 and ced-3 gene is necessary for apoptosis induction. In addition, we show that the Bar homeodomain transcription factor CEH-30 represses egl-1 and ced-3 transcription in the CEMs, thereby permitting their survival. Furthermore, we identified three genes, unc-86, lrs-1 and unc-132, which encode a POU homeodomain transcription factor, a leucyl-tRNA synthetase and a novel protein with limited sequence similarity to the mammalian proto-oncoprotein and kinase PIM-1, respectively, that promote the expression of the ceh-30 gene in the CEMs. Based on these results, we propose that egl-1 and ced-3 transcription are co-regulated in the CEMs to compensate for limiting proCED-3 levels, which most probably are a result of proCED-3 turn over. Similar co-regulatory mechanisms for BH3-only proteins and pro-caspases may function in higher organisms to allow efficient apoptosis induction during development. Finally, we present evidence that the timing of the death of the CEMs is controlled by TRA-1 Gli, the terminal global regulator of somatic sexual fate in C. elegans.
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28
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Nehme R, Conradt B. egl-1: a key activator of apoptotic cell death in C. elegans. Oncogene 2009; 27 Suppl 1:S30-40. [DOI: 10.1038/onc.2009.41] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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Lei H, Liu J, Fukushige T, Fire A, Krause M. Caudal-like PAL-1 directly activates the bodywall muscle module regulator hlh-1 in C. elegans to initiate the embryonic muscle gene regulatory network. Development 2009; 136:1241-9. [PMID: 19261701 DOI: 10.1242/dev.030668] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Previous work in C. elegans has shown that posterior embryonic bodywall muscle lineages are regulated through a genetically defined transcriptional cascade that includes PAL-1/Caudal-mediated activation of muscle-specific transcription factors, including HLH-1/MRF and UNC-120/SRF, which together orchestrate specification and differentiation. Using chromatin immunoprecipitation (ChIP) in embryos, we now demonstrate direct binding of PAL-1 in vivo to an hlh-1 enhancer element. Through mutational analysis of the evolutionarily conserved sequences within this enhancer, we identify two cis-acting elements and their associated transacting factors (PAL-1 and HLH-1) that are crucial for the temporal-spatial expression of hlh-1 and proper myogenesis. Our data demonstrate that hlh-1 is indeed a direct target of PAL-1 in the posterior embryonic C. elegans muscle lineages, defining a novel in vivo binding site for this crucial developmental regulator. We find that the same enhancer element is also a target of HLH-1 positive auto regulation, underlying (at least in part) the sustained high levels of CeMyoD in bodywall muscle throughout development. Together, these results provide a molecular framework for the gene regulatory network activating the muscle module during embryogenesis.
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Affiliation(s)
- Haiyan Lei
- National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
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30
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Trithorax, Hox, and TALE-class homeodomain proteins ensure cell survival through repression of the BH3-only gene egl-1. Dev Biol 2009; 329:374-85. [PMID: 19254707 DOI: 10.1016/j.ydbio.2009.02.022] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2008] [Revised: 02/05/2009] [Accepted: 02/18/2009] [Indexed: 12/21/2022]
Abstract
Mutations that aberrantly activate trithorax-group proteins, Hox transcription factors and TALE-class Hox cofactors promote leukemogenesis, but their target genes critical for leukemogenesis remain largely unknown. Through genetic analyses in C. elegans, we find that the trithorax-group gene lin-59 and the TALE-class Hox cofactor unc-62 are required for survival of the VC motor neurons. With the goal of providing a model for how aberrantly active Hox complexes might promote leukemia, we elucidate the mechanism through which these new inhibitors of programmed cell death act: lin-59 maintains transcription of the Hox gene lin-39, while unc-62 promotes nuclear localization of the TALE-class Hox cofactor ceh-20. A LIN-39/CEH-20 complex binds the promoter of the pro-apoptotic BH3-only gene egl-1, repressing its transcription and ensuring survival of the VC neurons. In the absence of this regulatory mechanism, egl-1 is transcribed and the VC neurons die. Furthermore, ectopic expression of the Hox gene lin-39, as occurs for human Hox genes in leukemia, is sufficient to block death of some cells. This work identifies BH3-only pro-apoptotic genes as targets of Hox-mediated repression and suggests that aberrant activation of Hox networks may promote leukemia in part by inhibiting apoptosis.
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Abstract
The elimination of unwanted cells by programmed cell death is a common feature of animal development. Genetic studies in the nematode Caenorhabditis elegans, the fruit fly Drosophila melanogaster, and the mouse have not only revealed the molecular machineries that cause the programmed demise of specific cells, but have also allowed us to get a glimpse of the types of pathways that regulate these machineries during development. Rather than serving as a broad overview of programmed cell death during development, this review focuses on recent advances in our understanding of the regulation of specific programmed cell death events during nematode, fly, and mouse development. Recent studies have revealed that many of the regulatory pathways involved play additional important roles in development, which confirms that the programmed cell death fate is an integral aspect of animal development.
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Affiliation(s)
- Barbara Conradt
- Department of Genetics, Norris Cotton Cancer Center, Dartmouth Medical School, Hanover, New Hampshire 03755, USA.
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Greiss S, Hall J, Ahmed S, Gartner A. C. elegans SIR-2.1 translocation is linked to a proapoptotic pathway parallel to cep-1/p53 during DNA damage-induced apoptosis. Genes Dev 2008; 22:2831-42. [PMID: 18923081 DOI: 10.1101/gad.482608] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Caenorhabditis elegans SIR-2.1, a member of the sirtuin family related to Saccharomyces cerevisiae Sir2p, has previously been implicated in aging. The mammalian homolog SIRT1 plays important roles in multiple cellular processes including transcriptional repression and stress response. We show that sir-2.1 is essential for the execution of apoptosis in response to DNA damage, and that sir-2.1 genetically acts in parallel to the worm p53-like gene cep-1. This novel cep-1-independent proapoptotic pathway does not require the daf-16 FOXO transcription factor. Cytological analysis of SIR-2.1 suggests a novel mechanism of apoptosis induction. During apoptosis SIR-2.1 changes its subcellular localization from the nucleus to the cytoplasm and transiently colocalizes with the C. elegans Apaf-1 homolog CED-4 at the nuclear periphery. SIR-2.1 translocation is an early event in germ cell apoptosis and is independent of apoptosis execution and cep-1, raising the possibility that SIR-2.1 translocation is linked to the induction of DNA damage-induced apoptosis.
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Affiliation(s)
- Sebastian Greiss
- Wellcome Trust Centre for Gene Regulation and Expression, University of Dundee, Dundee DD1 5EH, United Kingdom
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33
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Abstract
Years of research have identified a highly conserved mechanism required for apoptotic cell killing. How certain cells are specified to die is not well understood. With a rich history in programmed cell death research, the nematode C. elegans offers an excellent animal model with which to study cell death specification events. Developing hermaphrodites have 131 invariant cell death events that can be studied with single cell resolution. Recent genetic studies have begun to identify diverse sets of factors required for the proper specification of individual cell death events. The limited findings thus far suggest that cell death specification is controlled through transcriptional regulation of at least two members of the core cell death pathway, egl-1 and ced-3. However, it remains unclear if additional modes of cell death specification exist. Here we briefly summarize current findings in the field of C. elegans cell death specification and consider those questions that remain to be answered.
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Affiliation(s)
- Erin Peden
- Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, Colorado 80309, USA
| | - Darrell J. Killian
- Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, Colorado 80309, USA
| | - Ding Xue
- Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, Colorado 80309, USA
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Blum ES, Driscoll M, Shaham S. Noncanonical cell death programs in the nematode Caenorhabditis elegans. Cell Death Differ 2008; 15:1124-31. [PMID: 18437162 DOI: 10.1038/cdd.2008.56] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Genetic studies of the nematode Caenorhabditis elegans have uncovered four genes, egl-1 (BH3 only), ced-9 (Bcl-2 related), ced-4 (apoptosis protease activating factor-1), and ced-3 (caspase), which function in a linear pathway to promote developmental cell death in this organism. While this core pathway functions in many cells, recent studies suggest that additional regulators, acting on or in lieu of these core genes, can promote or inhibit the onset of cell death. Here, we discuss the evidence for these noncanonical mechanisms of C. elegans cell death control. We consider novel modes for regulating the core apoptosis genes, and describe a newly identified cell death pathway independent of all known C. elegans cell death genes. The existence of these noncanonical cell death programs suggests that organisms have evolved multiple ways to ensure appropriate cellular demise during development.
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Affiliation(s)
- E S Blum
- Laboratory of Developmental Genetics, The Rockefeller University, New York, NY 10065, USA
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35
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Schwartz HT, Horvitz HR. The C. elegans protein CEH-30 protects male-specific neurons from apoptosis independently of the Bcl-2 homolog CED-9. Genes Dev 2008; 21:3181-94. [PMID: 18056428 DOI: 10.1101/gad.1607007] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The developmental control of apoptosis is fundamental and important. We report that the Caenorhabditis elegans Bar homeodomain transcription factor CEH-30 is required for the sexually dimorphic survival of the male-specific CEM (cephalic male) sensory neurons; the homologous cells of hermaphrodites undergo programmed cell death. We propose that the cell-type-specific anti-apoptotic gene ceh-30 is transcriptionally repressed by the TRA-1 transcription factor, the terminal regulator of sexual identity in C. elegans, to cause hermaphrodite-specific CEM death. The established mechanism for the regulation of specific programmed cell deaths in C. elegans is the transcriptional control of the BH3-only gene egl-1, which inhibits the Bcl-2 homolog ced-9; similarly, most regulation of vertebrate apoptosis involves the Bcl-2 superfamily. In contrast, ceh-30 acts within the CEM neurons to promote their survival independently of both egl-1 and ced-9. Mammalian ceh-30 homologs can substitute for ceh-30 in C. elegans. Mice lacking the ceh-30 homolog Barhl1 show a progressive loss of sensory neurons and increased sensory-neuron cell death. Based on these observations, we suggest that the function of Bar homeodomain proteins as cell-type-specific inhibitors of apoptosis is evolutionarily conserved.
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Affiliation(s)
- Hillel T Schwartz
- Howard Hughes Medical Institute and MIT Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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Domingos PM, Steller H. Pathways regulating apoptosis during patterning and development. Curr Opin Genet Dev 2007; 17:294-9. [PMID: 17629474 PMCID: PMC1989756 DOI: 10.1016/j.gde.2007.05.009] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2007] [Revised: 04/30/2007] [Accepted: 05/01/2007] [Indexed: 12/19/2022]
Abstract
The patterning and development of multicellular organisms require a precisely controlled balance between cell proliferation, differentiation and death. The regulation of apoptosis is an important aspect to achieve this balance, by eliminating unnecessary or mis-specified cells which, otherwise, may have harmful effects on the whole organism. Apoptosis is also important for the morphogenetic processes that occur during development and that lead to the sculpting of organs and other body structures. Here, we review recent progress in understanding how apoptosis is regulated during development, focusing on studies using Drosophila or Caenorhabditis elegans as model organisms.
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Affiliation(s)
- Pedro M Domingos
- Howard Hughes Medical Institute, The Rockefeller University, 1230 York Avenue, New York, NY 10021, USA
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Jia SH, Li MW, Zhou B, Liu WB, Zhang Y, Miao XX, Zeng R, Huang YP. Proteomic Analysis of Silk Gland Programmed Cell Death during Metamorphosis of the Silkworm Bombyx mori. J Proteome Res 2007; 6:3003-10. [PMID: 17608510 DOI: 10.1021/pr070043f] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The silk gland of the silkworm Bombyx mori undergoes programmed cell death (PCD) during pupal metamorphosis. On the basis of their morphological changes and the occurrence of a DNA ladder, the tissue cells were categorized into three groups: intact, committed, and dying. To identify the proteins involved in this process, we conducted a comparative proteomic analysis. Protein expression changes among the three different cell types were examined by two-dimensional gel electrophoresis. Among approximately 1000 reproducibly detected protein spots on each gel, 43 were down-regulated and 34 were up-regulated in PCD process. Mass spectrometry identified 17 differentially expressed proteins, including some well-studied proteins as well as some novel PCD related proteins, such as caspases, proteasome subunit, elongation factor, heat shock protein, and hypothetical proteins. Our results suggest that these proteins may participate in the silk gland PCD process of B. mori and, thus, provide new insights for this mechanism.
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Affiliation(s)
- Shi-hai Jia
- Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, PR China
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