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Sethi A, Wei H, Mishra N, Segos I, Lambie EJ, Zanin E, Conradt B. A caspase-RhoGEF axis contributes to the cell size threshold for apoptotic death in developing Caenorhabditis elegans. PLoS Biol 2022; 20:e3001786. [PMID: 36201522 PMCID: PMC9536578 DOI: 10.1371/journal.pbio.3001786] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Accepted: 08/08/2022] [Indexed: 11/05/2022] Open
Abstract
A cell's size affects the likelihood that it will die. But how is cell size controlled in this context and how does cell size impact commitment to the cell death fate? We present evidence that the caspase CED-3 interacts with the RhoGEF ECT-2 in Caenorhabditis elegans neuroblasts that generate "unwanted" cells. We propose that this interaction promotes polar actomyosin contractility, which leads to unequal neuroblast division and the generation of a daughter cell that is below the critical "lethal" size threshold. Furthermore, we find that hyperactivation of ECT-2 RhoGEF reduces the sizes of unwanted cells. Importantly, this suppresses the "cell death abnormal" phenotype caused by the partial loss of ced-3 caspase and therefore increases the likelihood that unwanted cells die. A putative null mutation of ced-3 caspase, however, is not suppressed, which indicates that cell size affects CED-3 caspase activation and/or activity. Therefore, we have uncovered novel sequential and reciprocal interactions between the apoptosis pathway and cell size that impact a cell's commitment to the cell death fate.
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Affiliation(s)
- Aditya Sethi
- Faculty of Biology, Center for Integrative Protein Sciences Munich (CIPSM), Ludwig-Maximilians-University Munich, Planegg-Martinsried, Germany
- Department of Cell & Developmental Biology, Division of Biosciences, University College London, London, United Kingdom
| | - Hai Wei
- Faculty of Biology, Center for Integrative Protein Sciences Munich (CIPSM), Ludwig-Maximilians-University Munich, Planegg-Martinsried, Germany
| | - Nikhil Mishra
- Faculty of Biology, Center for Integrative Protein Sciences Munich (CIPSM), Ludwig-Maximilians-University Munich, Planegg-Martinsried, Germany
| | - Ioannis Segos
- Department of Cell & Developmental Biology, Division of Biosciences, University College London, London, United Kingdom
| | - Eric J. Lambie
- Department of Cell & Developmental Biology, Division of Biosciences, University College London, London, United Kingdom
| | - Esther Zanin
- Faculty of Biology, Center for Integrative Protein Sciences Munich (CIPSM), Ludwig-Maximilians-University Munich, Planegg-Martinsried, Germany
- Department Biology, Friedrich-Alexander-University Erlangen-Nürnberg, Erlangen, Germany
| | - Barbara Conradt
- Department of Cell & Developmental Biology, Division of Biosciences, University College London, London, United Kingdom
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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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Zaitceva V, Kopeina GS, Zhivotovsky B. Anastasis: Return Journey from Cell Death. Cancers (Basel) 2021; 13:3671. [PMID: 34359573 PMCID: PMC8345212 DOI: 10.3390/cancers13153671] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Revised: 07/16/2021] [Accepted: 07/17/2021] [Indexed: 12/12/2022] Open
Abstract
For over 20 years, it has been a dogma that once the integrity of mitochondria is disrupted and proapoptotic proteins that are normally located in the intermembrane space of mitochondria appeared in the cytoplasm, the process of cell death becomes inevitable. However, it has been recently shown that upon removal of the death signal, even at the stage of disturbance in the mitochondria, cells can recover and continue to grow. This phenomenon was named anastasis. Here, we will critically discuss the present knowledge concerning the mechanisms of cell death reversal, or development of anastasis, methods for its detection, and what role signaling from different intracellular compartments plays in anastasis stimulation.
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Affiliation(s)
- Victoria Zaitceva
- Faculty of Medicine, MV Lomonosov Moscow State University, 119991 Moscow, Russia; (V.Z.); (G.S.K.)
| | - Gelina S. Kopeina
- Faculty of Medicine, MV Lomonosov Moscow State University, 119991 Moscow, Russia; (V.Z.); (G.S.K.)
| | - Boris Zhivotovsky
- Faculty of Medicine, MV Lomonosov Moscow State University, 119991 Moscow, Russia; (V.Z.); (G.S.K.)
- Division of Toxicology, Institute of Environmental Medicine, Karolinska Institutet, Box 210, 17177 Stockholm, Sweden
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PIG-1 MELK-dependent phosphorylation of nonmuscle myosin II promotes apoptosis through CES-1 Snail partitioning. PLoS Genet 2020; 16:e1008912. [PMID: 32946434 PMCID: PMC7527206 DOI: 10.1371/journal.pgen.1008912] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2020] [Revised: 09/30/2020] [Accepted: 07/29/2020] [Indexed: 01/06/2023] Open
Abstract
The mechanism(s) through which mammalian kinase MELK promotes tumorigenesis is not understood. We find that the C. elegans orthologue of MELK, PIG-1, promotes apoptosis by partitioning an anti-apoptotic factor. The C. elegans NSM neuroblast divides to produce a larger cell that differentiates into a neuron and a smaller cell that dies. We find that in this context, PIG-1 MELK is required for partitioning of CES-1 Snail, a transcriptional repressor of the pro-apoptotic gene egl-1 BH3-only. pig-1 MELK is controlled by both a ces-1 Snail- and par-4 LKB1-dependent pathway, and may act through phosphorylation and cortical enrichment of nonmuscle myosin II prior to neuroblast division. We propose that pig-1 MELK-induced local contractility of the actomyosin network plays a conserved role in the acquisition of the apoptotic fate. Our work also uncovers an auto-regulatory loop through which ces-1 Snail controls its own activity through the formation of a gradient of CES-1 Snail protein. Apoptosis is critical for the elimination of ‘unwanted’ cells. What distinguishes wanted from unwanted cells in developing animals is poorly understood. We report that in the C. elegans NSM neuroblast lineage, the level of CES-1, a Snail-family member and transcriptional repressor of the pro-apoptotic gene egl-1, contributes to this process. In addition, we demonstrate that C. elegans PIG-1, the orthologue of mammalian proto-oncoprotein MELK, plays a critical role in controlling CES-1Snail levels. Specifically, during NSM neuroblast division, PIG-1MELK controls partitioning of CES-1Snail into one but not the other daughter cell thereby promoting the making of one wanted and one unwanted cell. Furthermore, we present evidence that PIG-1MELK acts prior to NSM neuroblast division by locally activating the actomyosin network.
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Caenorhabditis elegans ced-3 Caspase Is Required for Asymmetric Divisions That Generate Cells Programmed To Die. Genetics 2018; 210:983-998. [PMID: 30194072 PMCID: PMC6218217 DOI: 10.1534/genetics.118.301500] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2018] [Accepted: 09/04/2018] [Indexed: 01/30/2023] Open
Abstract
Caspases have functions other than in apoptosis. Here, we report that Caenorhabditis elegans CED-3 caspase regulates asymmetric cell division. Many of the 131 cells that are "programmed" to die during C. elegans development are the smaller daughter of a neuroblast that divides asymmetrically by size and fate. We have previously shown that CED-3 caspase is activated in such neuroblasts, and that before neuroblast division, a gradient of CED-3 caspase activity is formed in a ced-1 MEGF10 ( m ultiple EGF -like domains 10 )-dependent manner. This results in the nonrandom segregation of active CED-3 caspase or "apoptotic potential" into the smaller daughter. We now show that CED-3 caspase is necessary for the ability of neuroblasts to divide asymmetrically by size. In addition, we provide evidence that a pig-1 MELK (maternal embryonic leucine zipper kinase)-dependent reciprocal gradient of "mitotic potential" is formed in the QL.p neuroblast, and that CED-3 caspase antagonizes this mitotic potential. Based on these findings, we propose that CED-3 caspase plays a critical role in the asymmetric division by size and fate of neuroblasts, and that this contributes to the reproducibility and robustness with which the smaller daughter cell is produced and adopts the apoptotic fate. Finally, the function of CED-3 caspase in this context is dependent on its activation through the conserved egl-1 BH3-only, ced-9 Bcl-2, and ced-4 Apaf-1 pathway. In mammals, caspases affect various aspects of stem cell lineages. We speculate that the new nonapoptotic function of C. elegans CED-3 caspase in asymmetric neuroblast division is relevant to the function(s) of mammalian caspases in stem cells.
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Wei H, Yan B, Gagneur J, Conradt B. Caenorhabditis elegans CES-1 Snail Represses pig-1 MELK Expression To Control Asymmetric Cell Division. Genetics 2017; 206:2069-2084. [PMID: 28652378 PMCID: PMC5560807 DOI: 10.1534/genetics.117.202754] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2017] [Accepted: 06/16/2017] [Indexed: 02/07/2023] Open
Abstract
Snail-like transcription factors affect stem cell function through mechanisms that are incompletely understood. In the Caenorhabditis elegans neurosecretory motor neuron (NSM) neuroblast lineage, CES-1 Snail coordinates cell cycle progression and cell polarity to ensure the asymmetric division of the NSM neuroblast and the generation of two daughter cells of different sizes and fates. We have previously shown that CES-1 Snail controls cell cycle progression by repressing the expression of cdc-25.2 CDC25. However, the mechanism through which CES-1 Snail affects cell polarity has been elusive. Here, we systematically searched for direct targets of CES-1 Snail by genome-wide profiling of CES-1 Snail binding sites and identified >3000 potential CES-1 Snail target genes, including pig-1, the ortholog of the oncogene maternal embryonic leucine zipper kinase (MELK). Furthermore, we show that CES-1 Snail represses pig-1 MELK transcription in the NSM neuroblast lineage and that pig-1 MELK acts downstream of ces-1 Snail to cause the NSM neuroblast to divide asymmetrically by size and along the correct cell division axis. Based on our results we propose that by regulating the expression of the MELK gene, Snail-like transcription factors affect the ability of stem cells to divide asymmetrically and, hence, to self-renew. Furthermore, we speculate that the deregulation of MELK contributes to tumorigenesis by causing cells that normally divide asymmetrically to divide symmetrically instead.
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Affiliation(s)
- Hai Wei
- Center for Integrated Protein Science Munich - CIPSM, Department Biology II, Ludwig-Maximilians-University Munich, 82152 Planegg-Martinsried, Germany
| | - Bo Yan
- Center for Integrated Protein Science Munich - CIPSM, Department Biology II, Ludwig-Maximilians-University Munich, 82152 Planegg-Martinsried, Germany
| | - Julien Gagneur
- Gene Center Munich, Ludwig-Maximilians-University Munich, 81377 Munich, Germany
| | - Barbara Conradt
- Center for Integrated Protein Science Munich - CIPSM, Department Biology II, Ludwig-Maximilians-University Munich, 82152 Planegg-Martinsried, Germany
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Sherrard R, Luehr S, Holzkamp H, McJunkin K, Memar N, Conradt B. miRNAs cooperate in apoptosis regulation during C. elegans development. Genes Dev 2017; 31:209-222. [PMID: 28167500 PMCID: PMC5322734 DOI: 10.1101/gad.288555.116] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Accepted: 01/11/2017] [Indexed: 12/19/2022]
Abstract
Sherrard et al. demonstrate that, during embryogenesis, miR-35 and miR-58 bantam family miRNAs cooperate to prevent the precocious death of mothers of cells programmed to die by repressing the gene egl-1, which encodes a proapoptotic BH3-only protein. Programmed cell death occurs in a highly reproducible manner during Caenorhabditis elegans development. We demonstrate that, during embryogenesis, miR-35 and miR-58 bantam family microRNAs (miRNAs) cooperate to prevent the precocious death of mothers of cells programmed to die by repressing the gene egl-1, which encodes a proapoptotic BH3-only protein. In addition, we present evidence that repression of egl-1 is dependent on binding sites for miR-35 and miR-58 family miRNAs within the egl-1 3′ untranslated region (UTR), which affect both mRNA copy number and translation. Furthermore, using single-molecule RNA fluorescent in situ hybridization (smRNA FISH), we show that egl-1 is transcribed in the mother of a cell programmed to die and that miR-35 and miR-58 family miRNAs prevent this mother from dying by keeping the copy number of egl-1 mRNA below a critical threshold. Finally, miR-35 and miR-58 family miRNAs can also dampen the transcriptional boost of egl-1 that occurs specifically in a daughter cell that is programmed to die. We propose that miRNAs compensate for lineage-specific differences in egl-1 transcriptional activation, thus ensuring that EGL-1 activity reaches the threshold necessary to trigger death only in daughter cells that are programmed to die.
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Affiliation(s)
- Ryan Sherrard
- Center for Integrated Protein Science Munich - CIPSM, Department Biology II, Ludwig-Maximilians-University Munich, Planegg-Martinsried 82152, Germany
| | - Sebastian Luehr
- Center for Integrated Protein Science Munich - CIPSM, Department Biology II, Ludwig-Maximilians-University Munich, Planegg-Martinsried 82152, Germany
| | - Heinke Holzkamp
- Center for Integrated Protein Science Munich - CIPSM, Department Biology II, Ludwig-Maximilians-University Munich, Planegg-Martinsried 82152, Germany
| | - Katherine McJunkin
- Program in Molecular Medicine, RNA Therapeutics Institute, University of Massachusetts Medical School, Worcester, Massachusetts 01606, USA
| | - Nadin Memar
- Center for Integrated Protein Science Munich - CIPSM, Department Biology II, Ludwig-Maximilians-University Munich, Planegg-Martinsried 82152, Germany
| | - Barbara Conradt
- Center for Integrated Protein Science Munich - CIPSM, Department Biology II, Ludwig-Maximilians-University Munich, Planegg-Martinsried 82152, Germany
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