1
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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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2
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Baena-Lopez LA, Wang L, Wendler F. Cellular stress management by caspases. Curr Opin Cell Biol 2024; 86:102314. [PMID: 38215516 DOI: 10.1016/j.ceb.2023.102314] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2023] [Revised: 12/14/2023] [Accepted: 12/18/2023] [Indexed: 01/14/2024]
Abstract
Cellular stress plays a pivotal role in the onset of numerous human diseases. Consequently, the removal of dysfunctional cells, which undergo excessive stress-induced damage via various cell death pathways, including apoptosis, is essential for maintaining organ integrity and function. The evolutionarily conserved family of cysteine-aspartic-proteases, known as caspases, has been a key player in orchestrating apoptosis. However, recent research has unveiled the capability of these enzymes to govern fundamental cellular processes without triggering cell death. Remarkably, some of these non-lethal functions of caspases may contribute to restoring cellular equilibrium in stressed cells. This manuscript discusses how caspases can function as cellular stress managers and their potential impact on human health and disease. Additionally, it sheds light on the limitations of caspase-based therapies, given our still incomplete understanding of the biology of these enzymes, particularly in non-apoptotic contexts.
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Affiliation(s)
| | - Li Wang
- Sir William Dunn School of Pathology, University of Oxford, Oxford, OX13RE, UK
| | - Franz Wendler
- Sir William Dunn School of Pathology, University of Oxford, Oxford, OX13RE, UK. https://twitter.com/wendlerfranz
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3
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Jasper LA, Wang MC. Cutting through stress. Nat Metab 2024; 6:6-7. [PMID: 38167729 DOI: 10.1038/s42255-023-00946-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/05/2024]
Affiliation(s)
- Luis A Jasper
- University of California, Berkeley, Berkeley, CA, USA
| | - Meng C Wang
- Howard Hughes Medical Institute Janelia Research Campus, Ashburn, VA, USA.
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4
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Wei H, Weaver YM, Yang C, Zhang Y, Hu G, Karner CM, Sieber M, DeBerardinis RJ, Weaver BP. Proteolytic activation of fatty acid synthase signals pan-stress resolution. Nat Metab 2024; 6:113-126. [PMID: 38167727 PMCID: PMC10822777 DOI: 10.1038/s42255-023-00939-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Accepted: 11/06/2023] [Indexed: 01/05/2024]
Abstract
Chronic stress and inflammation are both outcomes and major drivers of many human diseases. Sustained responsiveness despite mitigation suggests a failure to sense resolution of the stressor. Here we show that a proteolytic cleavage event of fatty acid synthase (FASN) activates a global cue for stress resolution in Caenorhabditis elegans. FASN is well established for biosynthesis of the fatty acid palmitate. Our results demonstrate FASN promoting an anti-inflammatory profile apart from palmitate synthesis. Redox-dependent proteolysis of limited amounts of FASN by caspase activates a C-terminal fragment sufficient to downregulate multiple aspects of stress responsiveness, including gene expression, metabolic programs and lipid droplets. The FASN C-terminal fragment signals stress resolution in a cell non-autonomous manner. Consistent with these findings, FASN processing is also seen in well-fed but not fasted male mouse liver. As downregulation of stress responses is critical to health, our findings provide a potential pathway to control diverse aspects of stress responses.
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Affiliation(s)
- Hai Wei
- Department of Pharmacology, UT Southwestern, Dallas, TX, USA
| | - Yi M Weaver
- Department of Pharmacology, UT Southwestern, Dallas, TX, USA
| | - Chendong Yang
- Children's Medical Center Research Institute, UT Southwestern, Dallas, TX, USA
| | - Yuan Zhang
- Department of Pharmacology, UT Southwestern, Dallas, TX, USA
| | - Guoli Hu
- Department of Internal Medicine, UT Southwestern, Dallas, TX, USA
| | | | - Matthew Sieber
- Department of Physiology, UT Southwestern, Dallas, TX, USA
| | - Ralph J DeBerardinis
- Children's Medical Center Research Institute, UT Southwestern, Dallas, TX, USA
- Howard Hughes Medical Institute, UT Southwestern, Dallas, TX, USA
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5
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Brunette S, Sharma A, Bell R, Puente L, Megeney LA. Caspase 3 exhibits a yeast metacaspase proteostasis function that protects mitochondria from toxic TDP43 aggregates. MICROBIAL CELL (GRAZ, AUSTRIA) 2023; 10:157-169. [PMID: 37545643 PMCID: PMC10399456 DOI: 10.15698/mic2023.08.801] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Revised: 06/22/2023] [Accepted: 06/27/2023] [Indexed: 08/08/2023]
Abstract
Caspase 3 activation is a hallmark of cell death and there is a strong correlation between elevated protease activity and evolving pathology in neurodegenerative disease, such as amyotrophic lateral sclerosis (ALS). At the cellular level, ALS is characterized by protein aggregates and inclusions, comprising the RNA binding protein TDP-43, which are hypothesized to trigger pathogenic activation of caspase 3. However, a growing body of evidence indicates this protease is essential for ensuring cell viability during growth, differentiation and adaptation to stress. Here, we explored whether caspase 3 acts to disperse toxic protein aggregates, a proteostasis activity first ascribed to the distantly related yeast metacaspase ScMCA1. We demonstrate that human caspase 3 can functionally substitute for the ScMCA1 and limit protein aggregation in yeast, including TDP-43 inclusions. Proteomic analysis revealed that disrupting caspase 3 in the same yeast substitution model resulted in detrimental TDP-43/mitochondrial protein associations. Similarly, suppression of caspase 3, in either murine or human skeletal muscle cells, led to accumulation of TDP-43 aggregates and impaired mitochondrial function. These results suggest that caspase 3 is not inherently pathogenic, but may act as a compensatory proteostasis factor, to limit TDP-43 protein inclusions and protect organelle function in aggregation related degenerative disease.
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Affiliation(s)
- Steve Brunette
- Regenerative Medicine Program, Sprott Centre for Stem Cell Research, Ottawa Hospital Research Institute, The Ottawa Hospital, Ottawa, ON K1H 8L6, Canada
| | - Anupam Sharma
- Regenerative Medicine Program, Sprott Centre for Stem Cell Research, Ottawa Hospital Research Institute, The Ottawa Hospital, Ottawa, ON K1H 8L6, Canada
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON, Canada
| | - Ryan Bell
- Regenerative Medicine Program, Sprott Centre for Stem Cell Research, Ottawa Hospital Research Institute, The Ottawa Hospital, Ottawa, ON K1H 8L6, Canada
| | - Lawrence Puente
- Regenerative Medicine Program, Sprott Centre for Stem Cell Research, Ottawa Hospital Research Institute, The Ottawa Hospital, Ottawa, ON K1H 8L6, Canada
| | - Lynn A Megeney
- Regenerative Medicine Program, Sprott Centre for Stem Cell Research, Ottawa Hospital Research Institute, The Ottawa Hospital, Ottawa, ON K1H 8L6, Canada
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON, Canada
- Department of Medicine, University of Ottawa, Ottawa, ON, Canada
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6
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Yuan W, Weaver YM, Earnest S, Taylor CA, Cobb MH, Weaver BP. Modulating p38 MAPK signaling by proteostasis mechanisms supports tissue integrity during growth and aging. Nat Commun 2023; 14:4543. [PMID: 37507441 PMCID: PMC10382525 DOI: 10.1038/s41467-023-40317-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Accepted: 07/21/2023] [Indexed: 07/30/2023] Open
Abstract
The conserved p38 MAPK family is activated by phosphorylation during stress responses and inactivated by phosphatases. C. elegans PMK-1 p38 MAPK initiates innate immune responses and blocks development when hyperactivated. Here we show that PMK-1 signaling is enhanced during early aging by modulating the stoichiometry of non-phospho-PMK-1 to promote tissue integrity and longevity. Loss of pmk-1 function accelerates progressive declines in neuronal integrity and lysosome function compromising longevity which has both cell autonomous and cell non-autonomous contributions. CED-3 caspase cleavage limits phosphorylated PMK-1. Enhancing p38 signaling with caspase cleavage-resistant PMK-1 protects lysosomal and neuronal integrity extending a youthful phase. PMK-1 works through a complex transcriptional program to regulate lysosome formation. During early aging, the absolute phospho-p38 amount is maintained but the reservoir of non-phospho-p38 diminishes to enhance signaling without hyperactivation. Our findings show that modulating the stoichiometry of non-phospho-p38 dynamically supports tissue-homeostasis during aging without hyper-activation of stress response.
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Affiliation(s)
- Wang Yuan
- Department of Pharmacology, UT Southwestern Medical Center, Dallas, TX, USA
| | - Yi M Weaver
- Department of Pharmacology, UT Southwestern Medical Center, Dallas, TX, USA
| | - Svetlana Earnest
- Department of Pharmacology, UT Southwestern Medical Center, Dallas, TX, USA
| | - Clinton A Taylor
- Department of Pharmacology, UT Southwestern Medical Center, Dallas, TX, USA
| | - Melanie H Cobb
- Department of Pharmacology, UT Southwestern Medical Center, Dallas, TX, USA
| | - Benjamin P Weaver
- Department of Pharmacology, UT Southwestern Medical Center, Dallas, TX, USA.
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7
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Martin-Vega A, Earnest S, Augustyn A, Wichaidit C, Gazdar A, Girard L, Peyton M, Kollipara RK, Minna JD, Johnson JE, Cobb MH. ASCL1-ERK1/2 Axis: ASCL1 restrains ERK1/2 via the dual specificity phosphatase DUSP6 to promote survival of a subset of neuroendocrine lung cancers. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.15.545148. [PMID: 37398419 PMCID: PMC10312738 DOI: 10.1101/2023.06.15.545148] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/04/2023]
Abstract
The transcription factor achaete-scute complex homolog 1 (ASCL1) is a lineage oncogene that is central for the growth and survival of small cell lung cancers (SCLC) and neuroendocrine non-small cell lung cancers (NSCLC-NE) that express it. Targeting ASCL1, or its downstream pathways, remains a challenge. However, a potential clue to overcoming this challenage has been information that SCLC and NSCLC-NE that express ASCL1 exhibit extremely low ERK1/2 activity, and efforts to increase ERK1/2 activity lead to inhibition of SCLC growth and surival. Of course, this is in dramatic contrast to the majority of NSCLCs where high activity of the ERK pathway plays a major role in cancer pathogenesis. A major knowledge gap is defining the mechanism(s) underlying the low ERK1/2 activity in SCLC, determining if ERK1/2 activity and ASCL1 function are inter-related, and if manipulating ERK1/2 activity provides a new therapeutic strategy for SCLC. We first found that expression of ERK signaling and ASCL1 have an inverse relationship in NE lung cancers: knocking down ASCL1 in SCLCs and NE-NSCLCs increased active ERK1/2, while inhibition of residual SCLC/NSCLC-NE ERK1/2 activity with a MEK inhibitor increased ASCL1 expression. To determine the effects of ERK activity on expression of other genes, we obtained RNA-seq from ASCL1-expressing lung tumor cells treated with an ERK pathway MEK inhibitor and identified down-regulated genes (such as SPRY4, ETV5, DUSP6, SPRED1) that potentially could influence SCLC/NSCLC-NE tumor cell survival. This led us to discover that genes regulated by MEK inhibition suppress ERK activation and CHIP-seq demonstrated these are bound by ASCL1. In addition, SPRY4, DUSP6, SPRED1 are known suppressors of the ERK1/2 pathway, while ETV5 regulates DUSP6. Survival of NE lung tumors was inhibited by activation of ERK1/2 and a subset of ASCL1-high NE lung tumors expressed DUSP6. Because the dual specificity phosphatase 6 (DUSP6) is an ERK1/2-selective phosphatase that inactivates these kinases and has a pharmacologic inhibitor, we focused mechanistic studies on DUSP6. These studies showed: Inhibition of DUSP6 increased active ERK1/2, which accumulated in the nucleus; pharmacologic and genetic inhibition of DUSP6 affected proliferation and survival of ASCL1-high NE lung cancers; and that knockout of DUSP6 "cured" some SCLCs while in others resistance rapidly developed indicating a bypass mechanism was activated. Thus, our findings fill this knowledge gap and indicate that combined expression of ASCL1, DUSP6 and low phospho-ERK1/2 identify some neuroendocrine lung cancers for which DUSP6 may be a therapeutic target.
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8
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Hill C, Dellar ER, Baena‐Lopez LA. Caspases help to spread the message via extracellular vesicles. FEBS J 2023; 290:1954-1972. [PMID: 35246932 PMCID: PMC10952732 DOI: 10.1111/febs.16418] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2022] [Revised: 02/10/2022] [Accepted: 03/03/2022] [Indexed: 11/27/2022]
Abstract
Cell-cell communication is an essential aspect of multicellular life, key for coordinating cell proliferation, growth, and death in response to environmental changes. Whilst caspases are well-known for facilitating apoptotic and pyroptotic cell death, several recent investigations are uncovering new roles for these enzymes in biological scenarios requiring long-range intercellular signalling mediated by extracellular vesicles (EVs). EVs are small membrane-bound nanoparticles released from cells that may carry and deliver cargo between distant cells, thus helping to coordinate their behaviour. Intriguingly, there is emerging evidence indicating a key contribution of caspases in the biogenesis of EVs, the selection of their cargo content, and EV uptake/function in recipient cells. Here, we discuss the latest findings supporting the interplay between caspases and EVs, and the biological relevance of this molecular convergence for cellular signalling, principally in non-apoptotic scenarios.
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Affiliation(s)
- Claire Hill
- Sir William Dunn School of PathologyUniversity of OxfordUK
| | - Elizabeth R. Dellar
- Sir William Dunn School of PathologyUniversity of OxfordUK
- Nuffield Department of Clinical NeurosciencesUniversity of OxfordUK
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9
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Loss of MTCH-1 suppresses age-related proteostasis collapse through the inhibition of programmed cell death factors. Cell Rep 2022; 41:111690. [DOI: 10.1016/j.celrep.2022.111690] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Revised: 09/12/2022] [Accepted: 10/28/2022] [Indexed: 11/23/2022] Open
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10
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Geng S, Li Q, Zhou X, Zheng J, Liu H, Zeng J, Yang R, Fu H, Hao F, Feng Q, Qi B. Gut commensal E. coli outer membrane proteins activate the host food digestive system through neural-immune communication. Cell Host Microbe 2022; 30:1401-1416.e8. [PMID: 36057258 DOI: 10.1016/j.chom.2022.08.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Revised: 07/01/2022] [Accepted: 08/05/2022] [Indexed: 12/13/2022]
Abstract
The gastrointestinal tract facilitates food digestion, with the gut microbiota playing pivotal roles in nutrient breakdown and absorption. However, the microbial molecules and downstream signaling pathways that activate food digestion remain unexplored. Here, by establishing a food digestion system in C. elegans, we discover that food breakdown is regulated by the interaction between bacterial outer membrane proteins (OMPs) and a neural-immune pathway. E. coli OmpF/A activate digestion by increasing the neuropeptide NLP-12 that acts on the receptor CCKR. NLP-12 is homologous to mammalian cholecystokinin, known to stimulate dopamine, and we found that loss of dopamine receptors or addition of a dopamine antagonist inhibited OMP-mediated digestion. Dopamine and NLP-12-CKR-1 converge to inhibit PMK-1/p38 innate immune signaling. Moreover, directly inhibiting PMK-1/p38 boosts food digestion. This study uncovers a role of bacterial OMPs in regulating animal nutrient uptake and supports a key role for innate immunity in digestion.
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Affiliation(s)
- Shengya Geng
- Center for Life Sciences, School of Life Sciences, State Key Laboratory of Conservation and Utilization of Bio-Resources in Yunnan, Yunnan University, Kunming 650500, China
| | - Qian Li
- Center for Life Sciences, School of Life Sciences, State Key Laboratory of Conservation and Utilization of Bio-Resources in Yunnan, Yunnan University, Kunming 650500, China
| | - Xue Zhou
- Center for Life Sciences, School of Life Sciences, State Key Laboratory of Conservation and Utilization of Bio-Resources in Yunnan, Yunnan University, Kunming 650500, China
| | - Junkang Zheng
- Center for Life Sciences, School of Life Sciences, State Key Laboratory of Conservation and Utilization of Bio-Resources in Yunnan, Yunnan University, Kunming 650500, China
| | - Huimin Liu
- Center for Life Sciences, School of Life Sciences, State Key Laboratory of Conservation and Utilization of Bio-Resources in Yunnan, Yunnan University, Kunming 650500, China
| | - Jie Zeng
- Center for Life Sciences, School of Life Sciences, State Key Laboratory of Conservation and Utilization of Bio-Resources in Yunnan, Yunnan University, Kunming 650500, China
| | - Ruizhi Yang
- Center for Life Sciences, School of Life Sciences, State Key Laboratory of Conservation and Utilization of Bio-Resources in Yunnan, Yunnan University, Kunming 650500, China
| | - Herui Fu
- Center for Life Sciences, School of Life Sciences, State Key Laboratory of Conservation and Utilization of Bio-Resources in Yunnan, Yunnan University, Kunming 650500, China
| | - Fanrui Hao
- Center for Life Sciences, School of Life Sciences, State Key Laboratory of Conservation and Utilization of Bio-Resources in Yunnan, Yunnan University, Kunming 650500, China
| | - Qianxu Feng
- Center for Life Sciences, School of Life Sciences, State Key Laboratory of Conservation and Utilization of Bio-Resources in Yunnan, Yunnan University, Kunming 650500, China
| | - Bin Qi
- Center for Life Sciences, School of Life Sciences, State Key Laboratory of Conservation and Utilization of Bio-Resources in Yunnan, Yunnan University, Kunming 650500, China.
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11
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Jung JU, Ghosh A, Earnest S, Deaton SL, Cobb MH. UBR5 is a novel regulator of WNK1 stability. Am J Physiol Cell Physiol 2022; 322:C1176-C1186. [PMID: 35442829 DOI: 10.1152/ajpcell.00417.2021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The with no lysine (K) 1 (WNK1) protein kinase maintains cellular ion homeostasis in many tissues through actions on ion cotransporters and channels. Increased accumulation of WNK1 protein leads to pseudohypoaldosteronism type II (PHAII), a form of familial hypertension. WNK1 can be degraded via its adaptor-dependent recruitment to the Cullin3-RBX1 E3 ligase complex by the ubiquitin-proteasome system. Disruption of this process also leads to disease. To determine if this is the primary mechanism of WNK1 turnover, we examined WNK1 protein stability and degradation by measuring its rate of decay after blockade of translation. Here, we show that WNK1 protein degradation exhibits atypical kinetics in Hela cells. Consistent with this apparent complexity, we found that multiple degradative pathways can modulate cellular WNK1 protein amount. WNK1 protein is degraded not only by the proteasome, but also by the lysosome. Non-lysosomal cysteine proteases calpain and caspases also influence WNK1 degradation, as inhibitors of these proteases modestly increased WNK1 protein expression. Importantly, we discovered that the E3 ubiquitin ligase UBR5 interacts with WNK1 and its deficiency results in increased WNK1 protein. Our results further demonstrate that increased WNK1 in UBR5-depleted cells is attributable to reduced lysosomal degradation of WNK1 protein. Taken together, our findings provide insights into the multiplicity of degradative pathways involved in WNK1 turnover and uncover UBR5 as a previously unknown regulator of WNK1 protein stability that leads to lysosomal degradation of WNK1 protein.
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Affiliation(s)
- Ji-Ung Jung
- Department of Pharmacology, UT Southwestern Medical Center, Dallas, TX, United States
| | - Anwesha Ghosh
- Department of Pharmacology, UT Southwestern Medical Center, Dallas, TX, United States
| | - Svetlana Earnest
- Department of Pharmacology, UT Southwestern Medical Center, Dallas, TX, United States
| | - Staci L Deaton
- Department of Pharmacology, UT Southwestern Medical Center, Dallas, TX, United States
| | - Melanie H Cobb
- Department of Pharmacology, UT Southwestern Medical Center, Dallas, TX, United States
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12
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Xu DC, Wang L, Yamada KM, Baena-Lopez LA. Non-apoptotic activation of Drosophila caspase-2/9 modulates JNK signaling, the tumor microenvironment, and growth of wound-like tumors. Cell Rep 2022; 39:110718. [PMID: 35443185 PMCID: PMC9082238 DOI: 10.1016/j.celrep.2022.110718] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Revised: 02/15/2022] [Accepted: 03/31/2022] [Indexed: 11/23/2022] Open
Abstract
Resistance to apoptosis due to caspase deregulation is considered one of the main hallmarks of cancer. However, the discovery of novel non-apoptotic caspase functions has revealed unknown intricacies about the interplay between these enzymes and tumor progression. To investigate this biological problem, we capitalized on a Drosophila tumor model with human relevance based on the simultaneous overactivation of the EGFR and the JAK/STAT signaling pathways. Our data indicate that widespread non-apoptotic activation of initiator caspases limits JNK signaling and facilitates cell fate commitment in these tumors, thus preventing the overgrowth and exacerbation of malignant features of transformed cells. Intriguingly, caspase activity also reduces the presence of macrophage-like cells with tumor-promoting properties in the tumor microenvironment. These findings assign tumor-suppressing activities to caspases independent of apoptosis, while providing molecular details to better understand the contribution of these enzymes to tumor progression.
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Affiliation(s)
- Derek Cui Xu
- Cell Biology Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD 20892-4370, USA; Sir William Dunn School of Pathology, University of Oxford, Oxford, Oxfordshire OX1 3RE, UK
| | - Li Wang
- Sir William Dunn School of Pathology, University of Oxford, Oxford, Oxfordshire OX1 3RE, UK
| | - Kenneth M Yamada
- Cell Biology Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD 20892-4370, USA.
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13
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Fausett S, Poullet N, Gimond C, Vielle A, Bellone M, Braendle C. Germ cell apoptosis is critical to maintain Caenorhabditis elegans offspring viability in stressful environments. PLoS One 2021; 16:e0260573. [PMID: 34879088 PMCID: PMC8654231 DOI: 10.1371/journal.pone.0260573] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Accepted: 11/12/2021] [Indexed: 12/18/2022] Open
Abstract
Maintaining reproduction in highly variable, often stressful, environments is an essential challenge for all organisms. Even transient exposure to mild environmental stress may directly damage germ cells or simply tax the physiology of an individual, making it difficult to produce quality gametes. In Caenorhabditis elegans, a large fraction of germ cells acts as nurse cells, supporting developing oocytes before eventually undergoing so-called physiological germ cell apoptosis. Although C. elegans apoptosis has been extensively studied, little is known about how germline apoptosis is influenced by ecologically relevant environmental stress. Moreover, it remains unclear to what extent germline apoptosis contributes to maintaining oocyte quality, and thus offspring viability, in such conditions. Here we show that exposure to diverse environmental stressors, likely occurring in the natural C. elegans habitat (starvation, ethanol, acid, and mild oxidative stress), increases germline apoptosis, consistent with previous reports on stress-induced apoptosis. Using loss-of-function mutant alleles of ced-3 and ced-4, we demonstrate that eliminating the core apoptotic machinery strongly reduces embryonic survival when mothers are exposed to such environmental stressors during early adult life. In contrast, mutations in ced-9 and egl-1 that primarily block apoptosis in the soma but not in the germline, did not exhibit such reduced embryonic survival under environmental stress. Therefore, C. elegans germ cell apoptosis plays an essential role in maintaining offspring fitness in adverse environments. Finally, we show that ced-3 and ced-4 mutants exhibit concomitant decreases in embryo size and changes in embryo shape when mothers are exposed to environmental stress. These observations may indicate inadequate oocyte provisioning due to the absence of germ cell apoptosis. Taken together, our results show that the central genes of the apoptosis pathway play a key role in maintaining gamete quality, and thus offspring fitness, under ecologically relevant environmental conditions.
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Affiliation(s)
- Sarah Fausett
- Université Côte d’Azur, CNRS, Inserm, IBV, Nice, France
| | | | | | - Anne Vielle
- Université Côte d’Azur, CNRS, Inserm, IBV, Nice, France
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14
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Pujol N, Ewbank JJ. C. elegans: out on an evolutionary limb. Immunogenetics 2021; 74:63-73. [PMID: 34761293 DOI: 10.1007/s00251-021-01231-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Accepted: 10/22/2021] [Indexed: 12/18/2022]
Abstract
The natural environment of the free-living nematode Caenorhabditis elegans is rich in pathogenic microbes. There is now ample evidence to indicate that these pathogens exert a strong selection pressure on C. elegans, and have shaped its genome, physiology, and behaviour. In this short review, we concentrate on how C. elegans stands out from other animals in terms of its immune repertoire and innate immune signalling pathways. We discuss how C. elegans often detects pathogens because of their effects on essential cellular processes, or organelle integrity, in addition to direct microbial recognition. We illustrate the extensive molecular plasticity that is characteristic of immune defences in C. elegans and highlight some remarkable instances of lineage-specific innovation in innate immune mechanisms.
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Affiliation(s)
- Nathalie Pujol
- Aix Marseille Univ, CNRS, INSERM, CIML, Turing Centre for Living Systems, Marseille, France.
| | - Jonathan J Ewbank
- Aix Marseille Univ, CNRS, INSERM, CIML, Turing Centre for Living Systems, Marseille, France
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15
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An integrated view of innate immune mechanisms in C. elegans. Biochem Soc Trans 2021; 49:2307-2317. [PMID: 34623403 DOI: 10.1042/bst20210399] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Revised: 09/16/2021] [Accepted: 09/20/2021] [Indexed: 12/13/2022]
Abstract
The simple notion 'infection causes an immune response' is being progressively refined as it becomes clear that immune mechanisms cannot be understood in isolation, but need to be considered in a more global context with other cellular and physiological processes. In part, this reflects the deployment by pathogens of virulence factors that target diverse cellular processes, such as translation or mitochondrial respiration, often with great molecular specificity. It also reflects molecular cross-talk between a broad range of host signalling pathways. Studies with the model animal C. elegans have uncovered a range of examples wherein innate immune responses are intimately connected with different homeostatic mechanisms, and can influence reproduction, ageing and neurodegeneration, as well as various other aspects of its biology. Here we provide a short overview of a number of such connections, highlighting recent discoveries that further the construction of a fully integrated view of innate immunity.
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16
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Zhang X, Harding BW, Aggad D, Courtine D, Chen JX, Pujol N, Ewbank JJ. Antagonistic fungal enterotoxins intersect at multiple levels with host innate immune defences. PLoS Genet 2021; 17:e1009600. [PMID: 34166401 PMCID: PMC8263066 DOI: 10.1371/journal.pgen.1009600] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Revised: 07/07/2021] [Accepted: 05/12/2021] [Indexed: 12/25/2022] Open
Abstract
Animals and plants need to defend themselves from pathogen attack. Their defences drive innovation in virulence mechanisms, leading to never-ending cycles of co-evolution in both hosts and pathogens. A full understanding of host immunity therefore requires examination of pathogen virulence strategies. Here, we take advantage of the well-studied innate immune system of Caenorhabditis elegans to dissect the action of two virulence factors from its natural fungal pathogen Drechmeria coniospora. We show that these two enterotoxins have strikingly different effects when expressed individually in the nematode epidermis. One is able to interfere with diverse aspects of host cell biology, altering vesicle trafficking and preventing the key STAT-like transcription factor STA-2 from activating defensive antimicrobial peptide gene expression. The second increases STA-2 levels in the nucleus, modifies the nucleolus, and, potentially as a consequence of a host surveillance mechanism, causes increased defence gene expression. Our results highlight the remarkably complex and potentially antagonistic mechanisms that come into play in the interaction between co-evolved hosts and pathogens.
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Affiliation(s)
- Xing Zhang
- Aix Marseille Univ, CNRS, INSERM, CIML, Turing Centre for Living Systems, Marseille, France
| | - Benjamin W. Harding
- Aix Marseille Univ, CNRS, INSERM, CIML, Turing Centre for Living Systems, Marseille, France
| | - Dina Aggad
- Aix Marseille Univ, CNRS, INSERM, CIML, Turing Centre for Living Systems, Marseille, France
| | - Damien Courtine
- Aix Marseille Univ, CNRS, INSERM, CIML, Turing Centre for Living Systems, Marseille, France
| | | | - Nathalie Pujol
- Aix Marseille Univ, CNRS, INSERM, CIML, Turing Centre for Living Systems, Marseille, France
| | - Jonathan J. Ewbank
- Aix Marseille Univ, CNRS, INSERM, CIML, Turing Centre for Living Systems, Marseille, France
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17
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Abstract
In its natural habitat, C. elegans encounters a wide variety of microbes, including food, commensals and pathogens. To be able to survive long enough to reproduce, C. elegans has developed a complex array of responses to pathogens. These activities are coordinated on scales that range from individual organelles to the entire organism. Often, the response is triggered within cells, by detection of infection-induced damage, mainly in the intestine or epidermis. C. elegans has, however, a capacity for cell non-autonomous regulation of these responses. This frequently involves the nervous system, integrating pathogen recognition, altering host biology and governing avoidance behavior. Although there are significant differences with the immune system of mammals, some mechanisms used to limit pathogenesis show remarkable phylogenetic conservation. The past 20 years have witnessed an explosion of host-pathogen interaction studies using C. elegans as a model. This review will discuss the broad themes that have emerged and highlight areas that remain to be fully explored.
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Affiliation(s)
- Céline N Martineau
- Aix Marseille Université, Inserm, CNRS, CIML, Turing Centre for Living Systems, Marseille, France
| | | | - Nathalie Pujol
- Aix Marseille Université, Inserm, CNRS, CIML, Turing Centre for Living Systems, Marseille, France.
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18
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Canovas B, Nebreda AR. Diversity and versatility of p38 kinase signalling in health and disease. Nat Rev Mol Cell Biol 2021; 22:346-366. [PMID: 33504982 PMCID: PMC7838852 DOI: 10.1038/s41580-020-00322-w] [Citation(s) in RCA: 234] [Impact Index Per Article: 78.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/02/2020] [Indexed: 02/06/2023]
Abstract
The ability of cells to deal with different types of stressful situations in a precise and coordinated manner is key for survival and involves various signalling networks. Over the past 25 years, p38 kinases — in particular, p38α — have been implicated in the cellular response to stress at many levels. These span from environmental and intracellular stresses, such as hyperosmolarity, oxidative stress or DNA damage, to physiological situations that involve important cellular changes such as differentiation. Given that p38α controls a plethora of functions, dysregulation of this pathway has been linked to diseases such as inflammation, immune disorders or cancer, suggesting the possibility that targeting p38α could be of therapeutic interest. In this Review, we discuss the organization of this signalling pathway focusing on the diversity of p38α substrates, their mechanisms and their links to particular cellular functions. We then address how the different cellular responses can be generated depending on the signal received and the cell type, and highlight the roles of this kinase in human physiology and in pathological contexts. p38α — the best-characterized member of the p38 kinase family — is a key mediator of cellular stress responses. p38α is activated by a plethora of signals and functions through a multitude of substrates to regulate different cellular behaviours. Understanding context-dependent p38α signalling provides important insights into p38α roles in physiology and pathology.
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Affiliation(s)
- Begoña Canovas
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Barcelona, Spain
| | - Angel R Nebreda
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Barcelona, Spain. .,ICREA, Barcelona, Spain.
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19
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Yarychkivska O, Shaham S. Development or Disease: Caspases Balance Growth and Immunity in C. elegans. Dev Cell 2020; 53:259-260. [PMID: 32369740 DOI: 10.1016/j.devcel.2020.04.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Caspase proteases execute apoptosis but also function in development. In this issue of Developmental Cell, Weaver et al. report that C. elegans CED-3 caspase promotes animal growth through PMK-1/p38 kinase cleavage, and at the expense of pathogen and stress immunity, revealing an unexpected homeostatic relationship between development and disease.
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Affiliation(s)
- Olya Yarychkivska
- 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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20
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Arthurton L, Nahotko DA, Alonso J, Wendler F, Baena‐Lopez LA. Non-apoptotic caspase activation preserves Drosophila intestinal progenitor cells in quiescence. EMBO Rep 2020; 21:e48892. [PMID: 33135280 PMCID: PMC7726796 DOI: 10.15252/embr.201948892] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Revised: 09/21/2020] [Accepted: 10/01/2020] [Indexed: 12/11/2022] Open
Abstract
Caspase malfunction in stem cells often precedes the appearance and progression of multiple types of cancer, including human colorectal cancer. However, the caspase-dependent regulation of intestinal stem cell properties remains poorly understood. Here, we demonstrate that Dronc, the Drosophila ortholog of caspase-9/2 in mammals, limits the number of intestinal progenitor cells and their entry into the enterocyte differentiation programme. Strikingly, these unexpected roles for Dronc are non-apoptotic and have been uncovered under experimental conditions without epithelial replenishment. Supporting the non-apoptotic nature of these functions, we show that they require the enzymatic activity of Dronc, but are largely independent of the apoptotic pathway. Alternatively, our genetic and functional data suggest that they are linked to the caspase-mediated regulation of Notch signalling. Our findings provide novel insights into the non-apoptotic, caspase-dependent modulation of stem cell properties that could improve our understanding of the origin of intestinal malignancies.
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Affiliation(s)
- Lewis Arthurton
- Sir William Dunn School of PathologyUniversity of OxfordOxfordshireUK
| | | | - Jana Alonso
- Laboratorio de Agrobiología Juan José Bravo Rodríguez (Cabildo Insular de La Palma)Unidad Técnica del IPNA‐CSICSanta Cruz de La PalmaSpain
| | - Franz Wendler
- Sir William Dunn School of PathologyUniversity of OxfordOxfordshireUK
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