1
|
Wu Z, Cardona EA, Pierce JT. Non-apoptotic role of EGL-1 in exopher production and neuronal health in Caenorhabditis elegans. bioRxiv 2024:2024.04.19.590348. [PMID: 38712027 PMCID: PMC11071422 DOI: 10.1101/2024.04.19.590348] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2024]
Abstract
While traditionally studied for their pro-apoptotic functions, recent research suggests BH3-only proteins also have non-apoptotic roles. Here, we find that EGL-1, the BH3-only protein in Caenorhabditis elegans , promotes the cell-autonomous production of exophers in adult neurons. Exophers are large, micron-scale vesicles that are ejected from the cell and contain cellular components such as mitochondria. EGL-1 facilitates exopher production potentially through regulation of mitochondrial dynamics. Moreover, an endogenous, low level of EGL-1 expression appears to benefit dendritic health. Our findings provide insights into the mechanistic role of BH3-only protein in mitochondrial dynamics, downstream exopher production, and ultimately neuronal health. Significance statement BH3-only proteins were known for their function in inducing cell death. Their presence in healthy adult neurons, however, suggests additional roles. Our study focused on the BH3-only protein EGL-1 in the nematode Caenorhabditis elegans , where its apoptotic role was discovered. We reveal a new role in cell-autonomously promoting exopher production - a process where neurons extrude large vesicles containing potentially harmful cell contents. EGL-1 appears to promote this by regulating mitochondrial dynamics. We also report that low levels of EGL-1 benefit neuronal health and function. These findings expand our understanding of BH3-only proteins, mitochondrial dynamics, and exopher production in neurons and provide insights for neurodegenerative diseases.
Collapse
|
2
|
Wang P, Chen L, Wang N, Miao L, Zhao Y. Mitochondrial defects triggered by amg-1 mutation elicit UPRmt and phagocytic clearance during spermatogenesis in C. elegans. Development 2024; 151:dev202165. [PMID: 38224006 DOI: 10.1242/dev.202165] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Accepted: 01/04/2024] [Indexed: 01/16/2024]
Abstract
Mitochondria are the powerhouses of many biological processes. During spermatogenesis, post-transcriptional regulation of mitochondrial gene expression is mediated by nuclear-encoded mitochondrial RNA-binding proteins (mtRBPs). We identified AMG-1 as an mtRBP required for reproductive success in Caenorhabditis elegans. amg-1 mutation led to defects in mitochondrial structure and sperm budding, resulting in mitochondria being discarded into residual bodies, which ultimately delayed spermatogenesis in the proximal gonad. In addition, mitochondrial defects triggered the gonadal mitochondrial unfolded protein response and phagocytic clearance to ensure spermatogenesis but ultimately failed to rescue hermaphroditic fertility. These findings reveal a previously undiscovered role for AMG-1 in regulating C. elegans spermatogenesis, in which mitochondrial-damaged sperm prevented the transmission of defective mitochondria to mature sperm by budding and phagocytic clearance, a process which may also exist in the reproductive systems of higher organisms.
Collapse
Affiliation(s)
- Peng Wang
- Key Laboratory of RNA Biology, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Lianwan Chen
- Key Laboratory of RNA Biology, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Ning Wang
- Key Laboratory of RNA Biology, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Long Miao
- Key Laboratory of RNA Biology, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
- University of Chinese Academy of Sciences, Beijing 100049, China
- Center for Biological Imaging , Core Facilities for Protein Science, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
- MOE Key Laboratory of Cell Proliferation and Regulation Biology, College of Life Sciences, Beijing Normal University, Beijing 100875, China
| | - Yanmei Zhao
- Key Laboratory of RNA Biology, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| |
Collapse
|
3
|
Zhao R, Zhu Z, Geng R, Jiang X, Li W, Ou G. Inhibition of histone H3-H4 chaperone pathways rescues C. elegans sterility by H2B loss. PLoS Genet 2022; 18:e1010223. [PMID: 35679337 PMCID: PMC9216614 DOI: 10.1371/journal.pgen.1010223] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Revised: 06/22/2022] [Accepted: 04/28/2022] [Indexed: 12/14/2022] Open
Abstract
Oncohistone mutations are crucial drivers for tumorigenesis, but how a living organism governs the loss-of-function oncohistone remains unclear. We generated a histone H2B triple knockout (3KO) strain in Caenorhabditis elegans, which decreased the embryonic H2B, disrupted cell divisions, and caused animal sterility. By performing genetic suppressor screens, we uncovered that mutations defective in the histone H3-H4 chaperone UNC-85 restored H2B 3KO fertility by decreasing chromatin H3-H4 levels. RNA interference of other H3-H4 chaperones or H3 or H4 histones also rescued H2B 3KO sterility. We showed that blocking H3-H4 chaperones recovered cell division in C. elegans carrying the oncohistone H2BE74K mutation that distorts the H2B-H4 interface and induces nucleosome instability. Our results indicate that reducing chromatin H3-H4 rescues the dysfunctional H2B in vivo and suggest that inhibiting H3-H4 chaperones may provide an effective therapeutic strategy for treating cancers resulting from loss-of-function H2B oncohistone.
Collapse
Affiliation(s)
- Ruixue Zhao
- Tsinghua-Peking Center for Life Sciences, Beijing Frontier Research Center for Biological Structure, McGovern Institute for Brain Research, School of Life Sciences and MOE Key Laboratory for Protein Science, Tsinghua University, Beijing, China
| | - Zhiwen Zhu
- Tsinghua-Peking Center for Life Sciences, Beijing Frontier Research Center for Biological Structure, McGovern Institute for Brain Research, School of Life Sciences and MOE Key Laboratory for Protein Science, Tsinghua University, Beijing, China
| | - Ruxu Geng
- Tsinghua-Peking Center for Life Sciences, Beijing Frontier Research Center for Biological Structure, McGovern Institute for Brain Research, School of Life Sciences and MOE Key Laboratory for Protein Science, Tsinghua University, Beijing, China
| | - Xuguang Jiang
- Tsinghua-Peking Center for Life Sciences, Beijing Frontier Research Center for Biological Structure, McGovern Institute for Brain Research, School of Life Sciences and MOE Key Laboratory for Protein Science, Tsinghua University, Beijing, China
| | - Wei Li
- School of Medicine, Tsinghua University, Beijing, China
| | - Guangshuo Ou
- Tsinghua-Peking Center for Life Sciences, Beijing Frontier Research Center for Biological Structure, McGovern Institute for Brain Research, School of Life Sciences and MOE Key Laboratory for Protein Science, Tsinghua University, Beijing, China
| |
Collapse
|
4
|
Koyiloth M, Gummadi SN. Regulation and functions of membrane lipids: Insights from Caenorhabditis elegans. BBA Advances 2022; 2:100043. [PMID: 37082601 PMCID: PMC10074978 DOI: 10.1016/j.bbadva.2022.100043] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Revised: 12/28/2021] [Accepted: 01/12/2022] [Indexed: 02/08/2023] Open
Abstract
The Caenorhabditis elegans plasma membrane is composed of glycerophospholipids and sphingolipids with a small cholesterol. The C. elegans obtain the majority of the membrane lipids by modifying fatty acids present in the bacterial diet. The metabolic pathways of membrane lipid biosynthesis are well conserved across the animal kingdom. In C. elegans CDP-DAG and Kennedy pathway produce glycerophospholipids. Meanwhile, the sphingolipids are synthesized through a different pathway. They have evolved remarkably diverse mechanisms to maintain membrane lipid homeostasis. For instance, the lipid bilayer stress operates to accomplish homeostasis during any perturbance in the lipid composition. Meanwhile, the PAQR-2/IGLR-2 complex works with FLD-1 to balance unsaturated to saturated fatty acids to maintain membrane fluidity. The loss of membrane lipid homeostasis is observed in many human genetic and metabolic disorders. Since C. elegans conserved such genes and pathways, it can be used as a model organism.
Collapse
|
5
|
Liu G, Gao H, Chen J, Shao C, Wang P. Metronidazole Determination in Raw Milk with a Graphene Aerogel-Based Electrochemiluminescent Sensor and Its Effect on Cell Apoptosis. FOOD ANAL METHOD 2021; 14:1415-1424. [DOI: 10.1007/s12161-021-01982-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
|
6
|
Raiders S, Black EC, Bae A, MacFarlane S, Klein M, Shaham S, Singhvi A. Glia actively sculpt sensory neurons by controlled phagocytosis to tune animal behavior. eLife 2021; 10:63532. [PMID: 33759761 PMCID: PMC8079151 DOI: 10.7554/elife.63532] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Accepted: 03/23/2021] [Indexed: 02/07/2023] Open
Abstract
Glia in the central nervous system engulf neuron fragments to remodel synapses and recycle photoreceptor outer segments. Whether glia passively clear shed neuronal debris or actively prune neuron fragments is unknown. How pruning of single-neuron endings impacts animal behavior is also unclear. Here, we report our discovery of glia-directed neuron pruning in Caenorhabditis elegans. Adult C. elegans AMsh glia engulf sensory endings of the AFD thermosensory neuron by repurposing components of the conserved apoptotic corpse phagocytosis machinery. The phosphatidylserine (PS) flippase TAT-1/ATP8A functions with glial PS-receptor PSR-1/PSR and PAT-2/α-integrin to initiate engulfment. This activates glial CED-10/Rac1 GTPase through the ternary GEF complex of CED-2/CrkII, CED-5/DOCK180, CED-12/ELMO. Execution of phagocytosis uses the actin-remodeler WSP-1/nWASp. This process dynamically tracks AFD activity and is regulated by temperature, the AFD sensory input. Importantly, glial CED-10 levels regulate engulfment rates downstream of neuron activity, and engulfment-defective mutants exhibit altered AFD-ending shape and thermosensory behavior. Our findings reveal a molecular pathway underlying glia-dependent engulfment in a peripheral sense-organ and demonstrate that glia actively engulf neuron fragments, with profound consequences on neuron shape and animal sensory behavior. Neurons are tree-shaped cells that receive information through endings connected to neighbouring cells or the environment. Controlling the size, number and location of these endings is necessary to ensure that circuits of neurons get precisely the right amount of input from their surroundings. Glial cells form a large portion of the nervous system, and they are tasked with supporting, cleaning and protecting neurons. In humans, part of their duties is to ‘eat’ (or prune) unnecessary neuron endings. In fact, this role is so important that defects in glial pruning are associated with conditions such as Alzheimer’s disease. Yet it is still unknown how pruning takes place, and in particular whether it is the neuron or the glial cell that initiates the process. To investigate this question, Raiders et al. enlisted the common laboratory animal Caenorhabditis elegans, a tiny worm with a simple nervous system where each neuron has been meticulously mapped out. First, the experiments showed that glial cells in C. elegans actually prune the endings of sensory neurons. Focusing on a single glia-neuron pair then revealed that the glial cell could trim the endings of a living neuron by redeploying the same molecular machinery it uses to clear dead cell debris. Compared to this debris-clearing activity, however, the glial cell takes a more nuanced approach to pruning: specifically, it can adjust the amount of trimming based on the activity load of the neuron. When Raiders et al. disrupted the glial pruning for a single temperature-sensing neuron, the worm lost its normal temperature preferences; this demonstrated how the pruning activity of a single glial cell can be linked to behavior. Taken together the experiments showcase how C. elegans can be used to study glial pruning. Further work using this model could help to understand how disease emerges when glial cells cannot perform their role, and to spot the genetic factors that put certain individuals at increased risk for neurological and sensory disorders.
Collapse
Affiliation(s)
- Stephan Raiders
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, United States.,Molecular and Cellular Biology Graduate Program, University of Washington, Seattle, United States
| | - Erik Calvin Black
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, United States
| | - Andrea Bae
- Laboratory of Developmental Genetics, The Rockefeller University, New York, United States.,Cellular Imaging Shared Resources, Fred Hutchinson Cancer Research Center, Seattle, United States
| | - Stephen MacFarlane
- Department of Physics and Department of Biology, University of Miami, Coral Gables, United States
| | - Mason Klein
- Department of Physics and Department of Biology, University of Miami, Coral Gables, United States
| | - Shai Shaham
- Laboratory of Developmental Genetics, The Rockefeller University, New York, United States
| | - Aakanksha Singhvi
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, United States.,Molecular and Cellular Biology Graduate Program, University of Washington, Seattle, United States.,Department of Biological Structure, University of Washington School of Medicine, Seattle, United States.,Brotman Baty Institute for Precision Medicine, Seattle, United States
| |
Collapse
|
7
|
Crofts AR. The modified Q-cycle: A look back at its development and forward to a functional model. Biochim Biophys Acta Bioenerg 2021; 1862:148417. [PMID: 33745972 DOI: 10.1016/j.bbabio.2021.148417] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Revised: 02/28/2021] [Accepted: 03/11/2021] [Indexed: 11/25/2022]
Abstract
On looking back at a lifetime of research, it is interesting to see, in the light of current progress, how things came to be, and to speculate on how things might be. I am delighted in the context of the Mitchell prize to have that excuse to present this necessarily personal view of developments in areas of my interests. I have focused on the Q-cycle and a few examples showing wider ramifications, since that had been the main interest of the lab in the 20 years since structures became available, - a watershed event in determining our molecular perspective. I have reviewed the evidence for our model for the mechanism of the first electron transfer of the bifurcated reaction at the Qo-site, which I think is compelling. In reviewing progress in understanding the second electron transfer, I have revisited some controversies to justify important conclusions which appear, from the literature, not to have been taken seriously. I hope this does not come over as nitpicking. The conclusions are important to the final section in which I develop an internally consistent mechanism for turnovers of the complex leading to a state similar to that observed in recent rapid-mix/freeze-quench experiments, reported three years ago. The final model is necessarily speculative but is open to test.
Collapse
Affiliation(s)
- Antony R Crofts
- Department of Biochemistry, 417 Roger Adams Laboratory, 600 South Mathews Avenue, Urbana, IL 61801, United States of America
| |
Collapse
|
8
|
Perez MA, Watts JL. Worms, Fat, and Death: Caenorhabditis elegans Lipid Metabolites Regulate Cell Death. Metabolites 2021; 11:metabo11020125. [PMID: 33672292 PMCID: PMC7926963 DOI: 10.3390/metabo11020125] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Revised: 02/19/2021] [Accepted: 02/19/2021] [Indexed: 12/28/2022] Open
Abstract
Caenorhabditis elegans is well-known as the model organism used to elucidate the genetic pathways underlying the first described form of regulated cell death, apoptosis. Since then, C. elegans investigations have contributed to the further understanding of lipids in apoptosis, especially the roles of phosphatidylserines and phosphatidylinositols. More recently, studies in C. elegans have shown that dietary polyunsaturated fatty acids can induce the non-apoptotic, iron-dependent form of cell death, ferroptosis. In this review, we examine the roles of various lipids in specific aspects of regulated cell death, emphasizing recent work in C. elegans.
Collapse
|
9
|
Raj A, Nachiappan V. Hydroquinone exposure accumulates neutral lipid by the activation of CDP-DAG pathway in Saccharomyces cerevisiae. Toxicol Res (Camb) 2021; 10:354-367. [PMID: 33884185 DOI: 10.1093/toxres/tfab005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Revised: 01/09/2021] [Accepted: 01/17/2021] [Indexed: 11/13/2022] Open
Abstract
Benzene metabolites (HQ and BQ) are toxic compounds and their presence in human cause alteration in cellular respiration and kidney damage. In the current study, Saccharomyces cerevisiae has been used as a model organism and acute exposure of hydroquinone (HQ) decreased cell growth and increased reactive oxygen species (ROS). The expression of apoptosis regulatory genes (YCA1, NUC1, YSP1 and AIF1) were increased with HQ exposure in the wild-type cells. HQ exposure in the wild-type cells altered both the phospholipid and neutral lipid levels. Phosphatidylcholine is a vital membrane lipid that has a vital role in membrane biogenesis and was increased significantly with HQ. The neutral lipid results were supported with lipid droplets data and mRNA expression study. The phospholipid knockouts (Kennedy pathway) accumulated neutral lipids via the CDP-DAG (cytidine-diphosphate-diacylglycerol) pathway genes both in the presence and absence of HQ.
Collapse
Affiliation(s)
- Abhishek Raj
- Biomembrane Lab, Department of Biochemistry, School of Life Sciences, Bharathidasan University, Tiruchirappalli 620024, Tamil Nadu, India
| | - Vasanthi Nachiappan
- Biomembrane Lab, Department of Biochemistry, School of Life Sciences, Bharathidasan University, Tiruchirappalli 620024, Tamil Nadu, India
| |
Collapse
|
10
|
Koyiloth M, Gummadi SN. Cholesterol interaction attenuates scramblase activity of SCRM-1 in the artificial membrane. Biochim Biophys Acta Biomembr 2021; 1863:183548. [PMID: 33417966 DOI: 10.1016/j.bbamem.2020.183548] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Revised: 12/15/2020] [Accepted: 12/16/2020] [Indexed: 01/09/2023]
Abstract
Phospholipid (PL) scramblases are single-pass transmembrane protein mediating bidirectional PL translocation. Previously in silico analysis of human PL scramblases, predicted the presence of an uncharacterized cholesterol-binding domain spanning partly in the transmembrane helix as well as in the adjacent extracellular coil. This domain was found to be universally conserved in diverse organisms like Caenorhabditis elegans. In this study, we investigated the saturable cholesterol-binding domain of SCRM-1 using fluorescence sterol binding assay, Stern-Volmer quenching, Förster resonance energy transfer, and CD spectroscopy. We observed high-affinity interaction between cholesterol and SCRM-1. Our results support a previous report, which showed that the cholesterol ordering effect reduced the scramblase activity of hPLSCR1. Considering the presence of a high-affinity binding sequence, we propose that the reduction in activity could partly be due to the cholesterol binding. To validate this, we generated a C-terminal helix (CTH) deletion construct (∆CTH SCRM-1) and a point mutation in the putative cholesterol-binding domain I273D SCRM-1. Deletion construct greatly reduced cholesterol affinity along with loss of scramblase activity. In contrast to this, I273D SCRM-1 retained scrambling activity in proteoliposomes containing ~30 mol% cholesterol but lost sterol binding ability. These results suggest that C-terminal helix is crucial for membrane insertion and in the lipid bilayer the scrambling activity of SCRM-1 is modulated through its interaction with cholesterol.
Collapse
|
11
|
Abstract
Phagocytosis is an essential process by which cellular debris and pathogens are cleared from the environment. Cells extend their plasma membrane to engulf objects and contain them within a limiting membrane for isolation from the cytosol or for intracellular degradation in phagolysosomes. The basic mechanisms of phagocytosis and intracellular clearance are well conserved between animals. Indeed, much of our understanding is derived from studies on the nematode worm, Caenorhabditis elegans. Here, we review the latest progress in understanding the mechanisms and functions of phagocytic clearance from C. elegans studies. In particular, we highlight new insights into phagocytic signaling pathways, phagosome formation and phagolysosome resolution, as well as the challenges in studying these cyclic processes.
Collapse
Affiliation(s)
- Piya Ghose
- Department of Biology, University of Texas, Arlington, TX, United States.
| | - Ann M Wehman
- Department of Biological Sciences, University of Denver, Denver, CO, United States.
| |
Collapse
|
12
|
Koyiloth M, Gummadi SN. Molecular cloning and biochemical characterization of the phospholipid scramblase SCRM-1 from Caenorhabditis elegans. Eur Biophys J 2020; 49:163-73. [DOI: 10.1007/s00249-020-01423-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2019] [Revised: 12/22/2019] [Accepted: 01/14/2020] [Indexed: 10/25/2022]
|
13
|
Sinha S, Renganathan A, Nagendra PB, Bhat V, Mathew BS, Rao MRS. AEBP1 down regulation induced cell death pathway depends on PTEN status of glioma cells. Sci Rep 2019; 9:14577. [PMID: 31601918 PMCID: PMC6787275 DOI: 10.1038/s41598-019-51068-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Accepted: 09/20/2019] [Indexed: 02/06/2023] Open
Abstract
Glioblastoma (GBM) is the most common aggressive form of brain cancer with overall dismal prognosis (10–12 months) despite all current multimodal treatments. Previously we identified adipocyte enhancer binding protein 1 (AEBP1) as a differentially regulated gene in GBM. On probing the role of AEBP1 over expression in glioblastoma, we found that both cellular proliferation and survival were affected upon AEBP1 silencing in glioma cells, resulting in cell death. In the present study we report that the classical caspase pathway components are not activated in cell death induced by AEBP1 down regulation in PTEN-deficient (U87MG and U138MG) cells. PARP-1 was not cleaved but over-activated under AEBP1 down regulation which leads to the synthesis of PAR in the nucleus triggering the release of AIF from the mitochondria. Subsequently, AIF translocates to the nucleus along with MIF causing chromatinolysis. AEBP1 positively regulates PI3KinaseCβ by the binding to AE-1 binding element in the PI3KinaseCβ promoter. Loss of PI3KinaseCβ expression under AEBP1 depleted condition leads to excessive DNA damage and activation of PARP-1. Furthermore, over expression of PIK3CB (in trans) in U138MG cells prevents DNA damage in these AEBP1 depleted cells. On the contrary, AEBP1 down regulation induces caspase-dependent cell death in PTEN-proficient (LN18 and LN229) cells. Ectopic expression of wild-type PTEN in PTEN-deficient U138MG cells results in the activation of canonical caspase and Akt dependent cell death. Collectively, our findings define AEBP1 as a potential oncogenic driver in glioma, with potential implications for therapeutic intervention.
Collapse
Affiliation(s)
- Swati Sinha
- Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advance Scientific Research, Bangalore, Karnataka, 560064, India
| | - Arun Renganathan
- Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advance Scientific Research, Bangalore, Karnataka, 560064, India.,Department of Surgery, Washington University in St. Louis, St. Louis, MO, USA
| | - Prathima B Nagendra
- Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advance Scientific Research, Bangalore, Karnataka, 560064, India.,Gynaecology Oncology Group, School of Biomedical Sciences and Pharmacy, University of Newcastle, Callaghan, New South Wales, Australia
| | - Vasudeva Bhat
- Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advance Scientific Research, Bangalore, Karnataka, 560064, India.,Department of Immunology, Faculty of Health Sciences, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Brian Steve Mathew
- Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advance Scientific Research, Bangalore, Karnataka, 560064, India
| | | |
Collapse
|
14
|
Liu G, Jin BK, Ma C, Chen Z, Zhu JJ. Potential-Resolved Electrochemiluminescence Nanoprobes for Visual Apoptosis Evaluation at Single-Cell Level. Anal Chem 2019; 91:6363-6370. [PMID: 30964659 DOI: 10.1021/acs.analchem.9b01401] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
In this work, a potential-resolved electrochemiluminescence (ECL) method is developed and used for the apoptosis diagnosis at the single-cell level. The apoptosis of cells usually induces the decreasing expression of epidermal growth factor receptor (EGFR) and promotes phosphatidylserine (PS) eversion on the cell membrane. Here, Au@L012 and g-C3N4 as ECL probes are functionalized with epidermal growth factor (EGF) and peptide (PSBP) to recognize the EGFR and PS on the cell surface, respectively, showing two well-separated ECL signals during a potential scanning. Experimental results reveal that the relative ECL change of g-C3N4 and Au@L012 correlates with the degree of apoptosis, which provides an accurate way to investigate apoptosis without interference that solely changes EGFR or PS. With a homemade ECL microscopy, we simultaneously evaluate the EGFR and PS expression of abundant individual cells and, therefore, achieve the visualization analysis of the apoptosis rate for normal and cancer cell samples. This strategy contributes to visually studying tumor markers and pushing the application of ECL imaging for the disease diagnosis at the single-cell level.
Collapse
Affiliation(s)
- Gen Liu
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering , Nanjing University , Nanjing , 210023 , China.,College of Chemistry and Chemical Engineering , Anhui University , Hefei , Anhui 230601 , China
| | - Bao-Kang Jin
- College of Chemistry and Chemical Engineering , Anhui University , Hefei , Anhui 230601 , China
| | - Cheng Ma
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering , Nanjing University , Nanjing , 210023 , China
| | - Zixuan Chen
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering , Nanjing University , Nanjing , 210023 , China
| | - Jun-Jie Zhu
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering , Nanjing University , Nanjing , 210023 , China
| |
Collapse
|
15
|
Starnes D, Unrine J, Chen C, Lichtenberg S, Starnes C, Svendsen C, Kille P, Morgan J, Baddar ZE, Spear A, Bertsch P, Chen KC, Tsyusko O. Toxicogenomic responses of Caenorhabditis elegans to pristine and transformed zinc oxide nanoparticles. Environ Pollut 2019; 247:917-926. [PMID: 30823346 DOI: 10.1016/j.envpol.2019.01.077] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Revised: 12/20/2018] [Accepted: 01/21/2019] [Indexed: 06/09/2023]
Abstract
Manufactured nanoparticles (MNPs) undergo transformation immediately after they enter wastewater treatment streams and during their partitioning to sewage sludge, which is applied to agricultural soils in form of biosolids. We examined toxicogenomic responses of the model nematode Caenorhabditis elegans to pristine and transformed ZnO-MNPs (phosphatized pZnO- and sulfidized sZnO-MNPs). To account for the toxicity due to dissolved Zn, a ZnSO4 treatment was included. Transformation of ZnO-MNPs reduced their toxicity by nearly ten-fold, while there was almost no difference in the toxicity of pristine ZnO-MNPs and ZnSO4. This combined with the fact that far more dissolved Zn was released from ZnO- compared to pZnO- or sZnO-MNPs, suggests that dissolution of pristine ZnO-MNPs is one of the main drivers of their toxicity. Transcriptomic responses at the EC30 for reproduction resulted in a total of 1161 differentially expressed genes. Fifty percent of the genes differentially expressed in the ZnSO4 treatment, including the three metal responsive genes (mtl-1, mtl-2 and numr-1), were shared among all treatments, suggesting that responses to all forms of Zn could be partially attributed to dissolved Zn. However, the toxicity and transcriptomic responses in all MNP treatments cannot be fully explained by dissolved Zn. Two of the biological pathways identified, one essential for protein biosynthesis (Aminoacyl-tRNA biosynthesis) and another associated with detoxification (ABC transporters), were shared among pristine and one or both transformed ZnO-MNPs, but not ZnSO4. When comparing pristine and transformed ZnO-MNPs, 66% and 40% of genes were shared between ZnO-MNPs and sZnO-MNPs or pZnO-MNPs, respectively. This suggests greater similarity in transcriptomic responses between ZnO-MNPs and sZnO-MNPs, while toxicity mechanisms are more distinct for pZnO-MNPs, where 13 unique biological pathways were identified. Based on these pathways, the toxicity of pZnO-MNPs is likely to be associated with their adverse effect on digestion and metabolism.
Collapse
Affiliation(s)
- Daniel Starnes
- Department of Plant and Soil Sciences, University of Kentucky, Lexington, KY, USA; Department of Math and Computer Science, Belmont University, Nashville, TN, USA
| | - Jason Unrine
- Department of Plant and Soil Sciences, University of Kentucky, Lexington, KY, USA
| | - Chun Chen
- Department of Plant and Soil Sciences, University of Kentucky, Lexington, KY, USA; State Key Laboratory of Crop Stress Biology in Arid Areas, College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, 712100, PR China
| | - Stuart Lichtenberg
- Department of Plant and Soil Sciences, University of Kentucky, Lexington, KY, USA
| | - Catherine Starnes
- Department of Math and Computer Science, Belmont University, Nashville, TN, USA; Biostatics, Epidemiology, and Research Design, Center for Clinical and Translational Science, University of Kentucky, Lexington, KY, USA
| | - Claus Svendsen
- Centre for Ecology and Hydrology, Maclean Building, Benson Lane, Crowmarsh Gifford, Wallingford, Oxon, OX10 8BB, UK
| | - Peter Kille
- Organisms and Environment Division, Cardiff School of Biosciences, Cardiff University, Cardiff, CF10 3AT, UK
| | - John Morgan
- Organisms and Environment Division, Cardiff School of Biosciences, Cardiff University, Cardiff, CF10 3AT, UK
| | - Zeinah Elhaj Baddar
- Department of Plant and Soil Sciences, University of Kentucky, Lexington, KY, USA
| | - Amanda Spear
- Department of Toxicology and Cancer Biology, University of Kentucky, Lexington, KY, USA
| | - Paul Bertsch
- Division of Land and Water, CSIRO, Ecosciences Precinct, Brisbane, QLD, Australia
| | - Kuey Chu Chen
- Department of Pharmacology and Nutritional Sciences, College of Medicine, University of Kentucky, Lexington, KY, USA
| | - Olga Tsyusko
- Department of Plant and Soil Sciences, University of Kentucky, Lexington, KY, USA.
| |
Collapse
|
16
|
Chen YZ, Klöditz K, Lee ES, Nguyen DP, Yuan Q, Johnson J, Lee-Yow Y, Hall A, Mitani S, Xia NS, Fadeel B, Xue D. Structure and function analysis of the C. elegans aminophospholipid translocase TAT-1. J Cell Sci 2019; 132:jcs.227660. [PMID: 30683797 DOI: 10.1242/jcs.227660] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2018] [Accepted: 01/21/2019] [Indexed: 11/20/2022] Open
Abstract
The Caenorhabditis elegans aminophospholipid translocase TAT-1 maintains phosphatidylserine (PS) asymmetry in the plasma membrane and regulates endocytic transport. Despite these important functions, the structure-function relationship of this protein is poorly understood. Taking advantage of the tat-1 mutations identified by the C. elegans million mutation project, we investigated the effects of 16 single amino acid substitutions on the two functions of the TAT-1 protein. Two substitutions that alter a highly conserved PISL motif in the fourth transmembrane domain and a highly conserved DKTGT phosphorylation motif, respectively, disrupt both functions of TAT-1, leading to a vesicular gut defect and ectopic PS exposure on the cell surface, whereas most other substitutions across the TAT-1 protein, often predicted to be deleterious by bioinformatics programs, do not affect the functions of TAT-1. These results provide in vivo evidence for the importance of the PISL and DKTGT motifs in P4-type ATPases and improve our understanding of the structure-function relationship of TAT-1. Our study also provides an example of how the C. elegans million mutation project helps decipher the structure, functions, and mechanisms of action of important genes.
Collapse
Affiliation(s)
- Yu-Zen Chen
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Katharina Klöditz
- Division of Molecular Toxicology, Institute of Environmental Medicine, Karolinska Institutet, Stockholm 17177, Sweden
| | - Eui-Seung Lee
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Diemmy Pham Nguyen
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Quan Yuan
- National Institute of Diagnostics and Vaccine Development in Infectious Diseases, Xiamen University, Xiamen, Fujian 361005, China
| | - Jack Johnson
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Yannick Lee-Yow
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Adam Hall
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Shohei Mitani
- Department of Physiology, School of Medicine, Tokyo Women's Medical University, Tokyo 162-8666, Japan
| | - Ning-Shao Xia
- National Institute of Diagnostics and Vaccine Development in Infectious Diseases, Xiamen University, Xiamen, Fujian 361005, China
| | - Bengt Fadeel
- Division of Molecular Toxicology, Institute of Environmental Medicine, Karolinska Institutet, Stockholm 17177, Sweden
| | - Ding Xue
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado Boulder, Boulder, CO 80309, USA
| |
Collapse
|
17
|
Abstract
Injuries to the central or peripheral nervous system frequently cause long-term disabilities because damaged neurons are unable to efficiently self-repair. This inherent deficiency necessitates the need for new treatment options aimed at restoring lost function to patients. Compared to humans, a number of species possess far greater regenerative capabilities, and can therefore provide important insights into how our own nervous systems can be repaired. In particular, several invertebrate species have been shown to rapidly initiate regeneration post-injury, allowing separated axon segments to re-join. This process, known as axonal fusion, represents a highly efficient repair mechanism as a regrowing axon needs to only bridge the site of damage and fuse with its separated counterpart in order to re-establish its original structure. Our recent findings in the nematode Caenorhabditis elegans have expanded the promise of axonal fusion by demonstrating that it can restore complete function to damaged neurons. Moreover, we revealed the importance of injury-induced changes in the composition of the axonal membrane for mediating axonal fusion, and discovered that the level of axonal fusion can be enhanced by promoting a neuron's intrinsic growth potential. A complete understanding of the molecular mechanisms controlling axonal fusion may permit similar approaches to be applied in a clinical setting.
Collapse
Affiliation(s)
- Jean-Sébastien Teoh
- Neuroscience Program, Monash Biomedicine Discovery Institute and Department of Anatomy and Developmental Biology, Monash University, Melbourne, Australia
| | - Michelle Yu-Ying Wong
- Neuroscience Program, Monash Biomedicine Discovery Institute and Department of Anatomy and Developmental Biology, Monash University, Melbourne, Australia
| | - Tarika Vijayaraghavan
- Neuroscience Program, Monash Biomedicine Discovery Institute and Department of Anatomy and Developmental Biology, Monash University, Melbourne, Australia
| | - Brent Neumann
- Neuroscience Program, Monash Biomedicine Discovery Institute and Department of Anatomy and Developmental Biology, Monash University, Melbourne, Australia
| |
Collapse
|
18
|
Preta G. Understanding the Dr. Jekyll and Mr. Hyde nature of apoptosis-inducing factor: future perspectives. Biomed J 2017; 40:239-40. [PMID: 28918913 DOI: 10.1016/j.bj.2017.06.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2017] [Accepted: 06/12/2017] [Indexed: 12/22/2022] Open
Abstract
Apoptosis-inducing factor (AIF) is emerging as a key protein in regulation of basic physiological processes including phagocytosis, mitophagy and regulation of the redox state. Recent evidences suggest that the enzymatic activity of AIF may play an active role in tumor progression controlling energy metabolism and redox balance. The present manuscript briefly describes the story of this protein from its initial discovery as caspase-independent apoptotic protein, throughout its role in oxidative phosphorylation and lately involvement in tumor progression. Understanding the dualistic nature of AIF is a critical starting point to clarify its contribution in tumor metabolic balance and to develop new AIF-specific therapeutic strategies.
Collapse
|
19
|
Conradt B, Wu YC, Xue D. Programmed Cell Death During Caenorhabditis elegans Development. Genetics 2016; 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] [What about the content of this article? (0)] [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.
Collapse
|
20
|
Yin J, Huang Y, Guo P, Hu S, Yoshina S, Xuan N, Gan Q, Mitani S, Yang C, Wang X. GOP-1 promotes apoptotic cell degradation by activating the small GTPase Rab2 in C. elegans. J Cell Biol 2017; 216:1775-1794. [PMID: 28424218 PMCID: PMC5461019 DOI: 10.1083/jcb.201610001] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2016] [Revised: 02/10/2017] [Accepted: 03/03/2017] [Indexed: 12/17/2022] Open
Abstract
Rab2 regulates multiple membrane traffic processes, but how it is recruited to and activated on the target membrane remains unclear. Here, Yin et al. identify a conserved protein, GOP-1, that activates UNC-108/Rab2 to promote phagosome, endosome, and DCV maturation. Apoptotic cells generated by programmed cell death are engulfed by phagocytes and enclosed within plasma membrane–derived phagosomes. Maturation of phagosomes involves a series of membrane-remodeling events that are governed by the sequential actions of Rab GTPases and lead to formation of phagolysosomes, where cell corpses are degraded. Here we identified gop-1 as a novel regulator of apoptotic cell clearance in Caenorhabditis elegans. Loss of gop-1 affects phagosome maturation through the RAB-5–positive stage, causing defects in phagosome acidification and phagolysosome formation, phenotypes identical to and unaffected by loss of unc-108, the C. elegans Rab2. GOP-1 transiently associates with cell corpse–containing phagosomes, and loss of its function abrogates phagosomal association of UNC-108. GOP-1 interacts with GDP-bound and nucleotide-free UNC-108/Rab2, disrupts GDI-UNC-108 complexes, and promotes activation and membrane recruitment of UNC-108/Rab2 in vitro. Loss of gop-1 also abolishes association of UNC-108 with endosomes, causing defects in endosome and dense core vesicle maturation. Thus, GOP-1 is an activator of UNC-108/Rab2 in multiple processes.
Collapse
Affiliation(s)
- Jianhua Yin
- National Institute of Biological Sciences, Beijing 102206, China.,Graduate Program in Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100730, China.,National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Yaling Huang
- National Institute of Biological Sciences, Beijing 102206, China
| | - Pengfei Guo
- National Institute of Biological Sciences, Beijing 102206, China
| | - Siqi Hu
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Sawako Yoshina
- Deparment of Physiology, School of Medicine and Institute for Integrated Medical Sciences, Tokyo Women's Medical University, Tokyo 162-8666, Japan
| | - Nan Xuan
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
| | - Qiwen Gan
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
| | - Shohei Mitani
- Deparment of Physiology, School of Medicine and Institute for Integrated Medical Sciences, Tokyo Women's Medical University, Tokyo 162-8666, Japan
| | - Chonglin Yang
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
| | - Xiaochen Wang
- National Institute of Biological Sciences, Beijing 102206, China .,Graduate Program in Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100730, China.,National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.,College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| |
Collapse
|
21
|
Klöditz K, Chen YZ, Xue D, Fadeel B. Programmed cell clearance: From nematodes to humans. Biochem Biophys Res Commun 2016; 482:491-497. [PMID: 27919685 DOI: 10.1016/j.bbrc.2016.12.005] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2016] [Accepted: 12/01/2016] [Indexed: 11/30/2022]
Abstract
Programmed cell clearance is a highly regulated physiological process of elimination of dying cells that occurs rapidly and efficiently in healthy organisms. It thus ensures proper development as well as homeostasis. Recent studies have disclosed a considerable degree of conservation of cell clearance pathways between nematodes and higher organisms. The externalization of the anionic phospholipid phosphatidylserine (PS) has emerged as an important "eat-me" signal for phagocytes and its exposition on apoptotic cells is controlled by phospholipid translocases and scramblases. However, there is mounting evidence that PS exposure occurs not only in apoptosis, but may also be actively expressed on the surface of cells undergoing other forms of cell death including necrosis; PS is also expressed on the surface of engulfing cells. Additionally, PS may act as a "save-me" signal during axonal regeneration. Here we discuss mechanisms of PS exposure and its recognition by phagocytes as well as the consequences of PS signaling in nematodes and in mammals.
Collapse
Affiliation(s)
- Katharina Klöditz
- Division of Molecular Toxicology, Institute of Environmental Medicine, Karolinska Institutet, 17177, Stockholm, Sweden
| | - Yu-Zen Chen
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO, 80309, USA
| | - Ding Xue
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO, 80309, USA
| | - Bengt Fadeel
- Division of Molecular Toxicology, Institute of Environmental Medicine, Karolinska Institutet, 17177, Stockholm, Sweden.
| |
Collapse
|
22
|
Lin JLJ, Wu CC, Yang WZ, Yuan HS. Crystal structure of endonuclease G in complex with DNA reveals how it nonspecifically degrades DNA as a homodimer. Nucleic Acids Res 2016; 44:10480-10490. [PMID: 27738134 PMCID: PMC5137453 DOI: 10.1093/nar/gkw931] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2016] [Revised: 10/05/2016] [Accepted: 10/07/2016] [Indexed: 01/20/2023] Open
Abstract
Endonuclease G (EndoG) is an evolutionarily conserved mitochondrial protein in eukaryotes that digests nucleus chromosomal DNA during apoptosis and paternal mitochondrial DNA during embryogenesis. Under oxidative stress, homodimeric EndoG becomes oxidized and converts to monomers with diminished nuclease activity. However, it remains unclear why EndoG has to function as a homodimer in DNA degradation. Here, we report the crystal structure of the Caenorhabditis elegans EndoG homologue, CPS-6, in complex with single-stranded DNA at a resolution of 2.3 Å. Two separate DNA strands are bound at the ββα-metal motifs in the homodimer with their nucleobases pointing away from the enzyme, explaining why CPS-6 degrades DNA without sequence specificity. Two obligatory monomeric CPS-6 mutants (P207E and K131D/F132N) were constructed, and they degrade DNA with diminished activity due to poorer DNA-binding affinity as compared to wild-type CPS-6. Moreover, the P207E mutant exhibits predominantly 3′-to-5′ exonuclease activity, indicating a possible endonuclease to exonuclease activity change. Thus, the dimer conformation of CPS-6 is essential for maintaining its optimal DNA-binding and endonuclease activity. Compared to other non-specific endonucleases, which are usually monomeric enzymes, EndoG is a unique dimeric endonuclease, whose activity hence can be modulated by oxidation to induce conformational changes.
Collapse
Affiliation(s)
- Jason L J Lin
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan 11529, ROC
| | - Chyuan-Chuan Wu
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan 11529, ROC
| | - Wei-Zen Yang
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan 11529, ROC
| | - Hanna S Yuan
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan 11529, ROC .,Graduate Institute of Biochemistry and Molecular Biology, National Taiwan University, Taiwan 10048, ROC
| |
Collapse
|
23
|
Chen X, Wang Y, Chen YZ, Harry BL, Nakagawa A, Lee ES, Guo H, Xue D. Regulation of CED-3 caspase localization and activation by C. elegans nuclear-membrane protein NPP-14. Nat Struct Mol Biol 2016; 23:958-64. [PMID: 27723735 DOI: 10.1038/nsmb.3308] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2015] [Accepted: 09/16/2016] [Indexed: 12/18/2022]
Abstract
Caspases are cysteine proteases with critical roles in apoptosis. The Caenorhabditis elegans caspase CED-3 is activated by autocatalytic cleavage, a process enhanced by CED-4. Here we report that the CED-3 zymogen localizes to the perinuclear region in C. elegans germ cells and that CED-3 autocatalytic cleavage is held in check by C. elegans nuclei and activated by CED-4. The nuclear-pore protein NPP-14 interacts with the CED-3 zymogen prodomain, colocalizes with CED-3 in vivo and inhibits CED-3 autoactivation in vitro. Several missense mutations in the CED-3 prodomain result in stronger association with NPP-14 and decreased CED-3 activation by CED-4 in the presence of nuclei or NPP-14, thus leading to cell-death defects. Those same mutations enhance autocatalytic cleavage of CED-3 in vitro and increase apoptosis in vivo in the absence of npp-14. Our results reveal a critical role of nuclei and nuclear-membrane proteins in regulating the activation and localization of CED-3.
Collapse
|
24
|
Zhou Q, Li H, Li H, Nakagawa A, Lin JLJ, Lee ES, Harry BL, Skeen-Gaar RR, Suehiro Y, William D, Mitani S, Yuan HS, Kang BH, Xue D. Mitochondrial endonuclease G mediates breakdown of paternal mitochondria upon fertilization. Science 2016; 353:394-9. [PMID: 27338704 DOI: 10.1126/science.aaf4777] [Citation(s) in RCA: 114] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2016] [Accepted: 06/15/2016] [Indexed: 12/26/2022]
Abstract
Mitochondria are inherited maternally in most animals, but the mechanisms of selective paternal mitochondrial elimination (PME) are unknown. While examining fertilization in Caenorhabditis elegans, we observed that paternal mitochondria rapidly lose their inner membrane integrity. CPS-6, a mitochondrial endonuclease G, serves as a paternal mitochondrial factor that is critical for PME. We found that CPS-6 relocates from the intermembrane space of paternal mitochondria to the matrix after fertilization to degrade mitochondrial DNA. It acts with maternal autophagy and proteasome machineries to promote PME. Loss of cps-6 delays breakdown of mitochondrial inner membranes, autophagosome enclosure of paternal mitochondria, and PME. Delayed removal of paternal mitochondria causes increased embryonic lethality, demonstrating that PME is important for normal animal development. Thus, CPS-6 functions as a paternal mitochondrial degradation factor during animal development.
Collapse
Affiliation(s)
- Qinghua Zhou
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO 80309, USA
| | - Haimin Li
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO 80309, USA
| | - Hanzeng Li
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO 80309, USA. Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO 80309, USA
| | - Akihisa Nakagawa
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO 80309, USA
| | - Jason L J Lin
- Institute of Molecular Biology, Academia Sinica, Taipei 11529, Taiwan
| | - Eui-Seung Lee
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO 80309, USA
| | - Brian L Harry
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO 80309, USA. Medical Scientist Training Program, University of Colorado, Aurora, CO 80045, USA
| | - Riley Robert Skeen-Gaar
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO 80309, USA
| | - Yuji Suehiro
- Department of Physiology, Tokyo Women's Medical University, School of Medicine and CREST, Japan Science and Technology Agency, Tokyo 162-8666, Japan
| | - Donna William
- Department of Microbiology and Cell Science, University of Florida, Gainesville, FL 32611, USA
| | - Shohei Mitani
- Department of Physiology, Tokyo Women's Medical University, School of Medicine and CREST, Japan Science and Technology Agency, Tokyo 162-8666, Japan
| | - Hanna S Yuan
- Institute of Molecular Biology, Academia Sinica, Taipei 11529, Taiwan
| | - Byung-Ho Kang
- School of Life Sciences, Centre for Cell and Developmental Biology and State Key Laboratory of Agrobiotechnology, Chinese University of Hong Kong, Hong Kong, China.
| | - Ding Xue
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO 80309, USA.
| |
Collapse
|
25
|
Lin JLJ, Nakagawa A, Skeen-Gaar R, Yang WZ, Zhao P, Zhang Z, Ge X, Mitani S, Xue D, Yuan HS. Oxidative Stress Impairs Cell Death by Repressing the Nuclease Activity of Mitochondrial Endonuclease G. Cell Rep 2016; 16:279-287. [PMID: 27346342 DOI: 10.1016/j.celrep.2016.05.090] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Revised: 04/28/2016] [Accepted: 05/22/2016] [Indexed: 01/22/2023] Open
Abstract
Endonuclease G (EndoG) is a mitochondrial protein that is released from mitochondria and relocated into the nucleus to promote chromosomal DNA fragmentation during apoptosis. Here, we show that oxidative stress causes cell-death defects in C. elegans through an EndoG-mediated cell-death pathway. In response to high reactive oxygen species (ROS) levels, homodimeric CPS-6-the C. elegans homolog of EndoG-is dissociated into monomers with diminished nuclease activity. Conversely, the nuclease activity of CPS-6 is enhanced, and its dimeric structure is stabilized by its interaction with the worm AIF homolog, WAH-1, which shifts to disulfide cross-linked dimers under high ROS levels. CPS-6 thus acts as a ROS sensor to regulate the life and death of cells. Modulation of the EndoG dimer conformation could present an avenue for prevention and treatment of diseases resulting from oxidative stress.
Collapse
Affiliation(s)
- Jason L J Lin
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan 11529, ROC
| | - Akihisa Nakagawa
- Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, CO 80309, USA
| | - Riley Skeen-Gaar
- Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, CO 80309, USA
| | - Wei-Zen Yang
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan 11529, ROC
| | - Pei Zhao
- School of Life Sciences and Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Tsinghua University, Beijing 100084, China
| | - Zhe Zhang
- School of Life Sciences and Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Tsinghua University, Beijing 100084, China
| | - Xiao Ge
- School of Life Sciences and Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Tsinghua University, Beijing 100084, China
| | - Shohei Mitani
- Department of Physiology, Tokyo Women's Medical University School of Medicine, Tokyo 162-8666, Japan; Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency, Tokyo 162-8666, Japan
| | - Ding Xue
- Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, CO 80309, USA; School of Life Sciences and Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Tsinghua University, Beijing 100084, China.
| | - Hanna S Yuan
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan 11529, ROC; Graduate Institute of Biochemistry and Molecular Biology, National Taiwan University, Taiwan 10048, ROC.
| |
Collapse
|
26
|
Cheng S, Wang K, Zou W, Miao R, Huang Y, Wang H, Wang X. PtdIns(4,5)P₂ and PtdIns3P coordinate to regulate phagosomal sealing for apoptotic cell clearance. J Cell Biol 2016; 210:485-502. [PMID: 26240185 PMCID: PMC4523610 DOI: 10.1083/jcb.201501038] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
A coincidence detection mechanism regulates phagosomal sealing and couples it with phosphoinositide conversion from PtdIns(4,5)P2 enrichment on unsealed phagosomes to PtdIns3P enrichment on fully sealed phagosomes. Phagocytosis requires phosphoinositides (PIs) as both signaling molecules and localization cues. How PIs coordinate to control phagosomal sealing and the accompanying switch of organelle identity is unclear. In this study, we followed dynamic changes in PIs during apoptotic cell clearance in Caenorhabditis elegans. We found that phosphatidylinositol-4,5-bisphosphate (PtdIns(4,5)P2) and phosphatidylinositol-3-phosphate (PtdIns3P), which accumulate transiently on unsealed and fully sealed phagosomes, respectively, are both involved in phagosome closure. We identified PtdIns3P phosphatase MTM-1 as an effector of PtdIns(4,5)P2 to promote phagosomal sealing. MTM-1 coordinates with the class II PI3 kinase PIKI-1 to control PtdIns3P levels on unsealed phagosomes. The SNX9 family protein LST-4 is required for sealing, and its association with unsealed phagosomes is regulated by PtdIns(4,5)P2, PIKI-1, and MTM-1. Loss of LST-4 or its retention on phagosomes disrupts sealing and suppresses PtdIns3P accumulation, indicating close coupling of the two events. Our findings support a coincidence detection mechanism by which phagosomal sealing is regulated and coupled with conversion from PtdIns(4,5)P2 enrichment on unsealed phagosomes to PtdIns3P enrichment on fully sealed phagosomes.
Collapse
Affiliation(s)
- Shiya Cheng
- Graduate Program, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100730, China National Institute of Biological Sciences, Beijing 102206, China
| | - Kun Wang
- National Institute of Biological Sciences, Beijing 102206, China
| | - Wei Zou
- National Institute of Biological Sciences, Beijing 102206, China
| | - Rui Miao
- National Institute of Biological Sciences, Beijing 102206, China
| | - Yaling Huang
- National Institute of Biological Sciences, Beijing 102206, China
| | - Haibin Wang
- National Institute of Biological Sciences, Beijing 102206, China
| | - Xiaochen Wang
- National Institute of Biological Sciences, Beijing 102206, China
| |
Collapse
|
27
|
Jafari G, Wasko BM, Kaeberlein M, Crofts AR. New functional and biophysical insights into the mitochondrial Rieske iron-sulfur protein from genetic suppressor analysis in C. elegans. Worm 2016; 5:e1174803. [PMID: 27383074 DOI: 10.1080/21624054.2016.1174803] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Revised: 03/23/2016] [Accepted: 03/30/2016] [Indexed: 10/22/2022]
Abstract
Several intragenic mutations suppress the C. elegans isp-1(qm150) allele of the mitochondrial Rieske iron-sulfur protein (ISP), a catalytic subunit of Complex III of the respiratory chain. These mutations were located in a helical region of the "tether" span of ISP-1, distant from the primary mutation in the extrinsic head, and suppressed all pleiotropic phenotypes associated with the qm150 allele. Analysis of these suppressors revealed control of electron transfer into Complex III through a "spring-loaded" mechanism involving a binding force for formation of enzyme-substrate complex, counter balanced by forces (a chemical "spring") favoring helix formation in the tether. The primary P→S mutation results in inhibition of electron flow into the Q-cycle by decreasing the binding force, and the tether mutations relieve this inhibition by weakening the "spring." In this commentary we discuss additional control features, and relate the primary inhibition to outcomes at the organismal level. In particular, the sensitivity to hyperoxia and the elevated reactive oxygen species (ROS) seen in isp-1(qm150), likely reflect over-reduction of the quinone pool, which is upstream of the inhibited site; at high O2, this would lead to increased ROS production through complex I. We speculate that alternative NADH:ubiquinone oxidoreductase activity in C. elegans from the worm apoptosis inducing factor (AIF) homolog (WAH-1) might also be involved, and that WAH-1 might have a "canary" function in detection of this adverse state (high O2/reduced pool), and a role in protection of the organism by transformation to AIF-like products, and apoptotic recycling of defective cells.
Collapse
Affiliation(s)
- Gholamali Jafari
- Massachusetts General Hospital, Harvard Medical School , Boston, MA, USA
| | - Brian M Wasko
- Department of Pathology, University of Washington , Seattle, WA, USA
| | - Matt Kaeberlein
- Department of Pathology, University of Washington , Seattle, WA, USA
| | - Antony R Crofts
- Department of Biochemistry, University of Illinois at Urbana-Champaign , Urbana, IL, USA
| |
Collapse
|
28
|
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 DOI: 10.1007/s00018-016-2196-z] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [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.
Collapse
|
29
|
Nichols ALA, Meelkop E, Linton C, Giordano-Santini R, Sullivan RK, Donato A, Nolan C, Hall DH, Xue D, Neumann B, Hilliard MA. The Apoptotic Engulfment Machinery Regulates Axonal Degeneration in C. elegans Neurons. Cell Rep 2016; 14:1673-1683. [PMID: 26876181 PMCID: PMC4821572 DOI: 10.1016/j.celrep.2016.01.050] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2014] [Revised: 12/23/2015] [Accepted: 01/13/2016] [Indexed: 01/31/2023] Open
Abstract
Axonal degeneration is a characteristic feature of neurodegenerative disease and nerve injury. Here, we characterize axonal degeneration in Caenorhabditis elegans neurons following laser-induced axotomy. We show that this process proceeds independently of the WLD(S) and Nmnat pathway and requires the axonal clearance machinery that includes the conserved transmembrane receptor CED-1/Draper, the adaptor protein CED-6, the guanine nucleotide exchange factor complex Crk/Mbc/dCed-12 (CED-2/CED-5/CED-12), and the small GTPase Rac1 (CED-10). We demonstrate that CED-1 and CED-6 function non-cell autonomously in the surrounding hypodermis, which we show acts as the engulfing tissue for the severed axon. Moreover, we establish a function in this process for CED-7, an ATP-binding cassette (ABC) transporter, and NRF-5, a lipid-binding protein, both associated with release of lipid-vesicles during apoptotic cell clearance. Thus, our results reveal the existence of a WLD(S)/Nmnat-independent axonal degeneration pathway, conservation of the axonal clearance machinery, and a function for CED-7 and NRF-5 in this process.
Collapse
Affiliation(s)
- Annika L A Nichols
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Ellen Meelkop
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Casey Linton
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Rosina Giordano-Santini
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Robert K Sullivan
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Alessandra Donato
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Cara Nolan
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - David H Hall
- Center for C. elegans Anatomy, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Ding Xue
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO 80309, USA
| | - Brent Neumann
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia.
| | - Massimo A Hilliard
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia.
| |
Collapse
|
30
|
Pinto SM, Almendinger J, Cabello J, Hengartner MO. Loss of Acetylcholine Signaling Reduces Cell Clearance Deficiencies in Caenorhabditis elegans. PLoS One 2016; 11:e0149274. [PMID: 26872385 PMCID: PMC4752328 DOI: 10.1371/journal.pone.0149274] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2015] [Accepted: 01/29/2016] [Indexed: 11/18/2022] Open
Abstract
The ability to eliminate undesired cells by apoptosis is a key mechanism to maintain organismal health and homeostasis. Failure to clear apoptotic cells efficiently can cause autoimmune diseases in mammals. Genetic studies in Caenorhabditis elegans have greatly helped to decipher the regulation of apoptotic cell clearance. In this study, we show that the loss of levamisole-sensitive acetylcholine receptor, but not of a typical neuronal acetylcholine receptor causes a reduction in the number of persistent cell corpses in worms suffering from an engulfment deficiency. This reduction is not caused by impaired or delayed cell death but rather by a partial restoration of the cell clearance capacity. Mutants in acetylcholine turn-over elicit a similar phenotype, implying that acetylcholine signaling is the process responsible for these observations. Surprisingly, tissue specific RNAi suggests that UNC-38, a major component of the levamisole-sensitive receptor, functions in the dying germ cell to influence engulfment efficiency. Animals with loss of acetylcholine receptor exhibit a higher fraction of cell corpses positive for the “eat-me” signal phosphatidylserine. Our results suggest that modulation by ion channels of ion flow across plasma membrane in dying cells can influence the dynamics of phosphatidylserine exposure and thus clearance efficiency.
Collapse
Affiliation(s)
- Sérgio M. Pinto
- Institute of Molecular Life Sciences, University of Zurich, Zurich, Switzerland
- Graduate Program in Areas of Basic and Applied Biology, University of Porto, Porto, Portugal
| | - Johann Almendinger
- Institute of Molecular Life Sciences, University of Zurich, Zurich, Switzerland
| | - Juan Cabello
- Center for Biomedical Research of La Rioja (CIBIR), Logroño, La Rioja, Spain
| | - Michael O. Hengartner
- Institute of Molecular Life Sciences, University of Zurich, Zurich, Switzerland
- * E-mail:
| |
Collapse
|
31
|
Li Z, Venegas V, Nagaoka Y, Morino E, Raghavan P, Audhya A, Nakanishi Y, Zhou Z. Necrotic Cells Actively Attract Phagocytes through the Collaborative Action of Two Distinct PS-Exposure Mechanisms. PLoS Genet 2015; 11:e1005285. [PMID: 26061275 DOI: 10.1371/journal.pgen.1005285] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2015] [Accepted: 05/14/2015] [Indexed: 11/19/2022] Open
Abstract
Necrosis, a kind of cell death closely associated with pathogenesis and genetic programs, is distinct from apoptosis in both morphology and mechanism. Like apoptotic cells, necrotic cells are swiftly removed from animal bodies to prevent harmful inflammatory and autoimmune responses. In the nematode Caenorhabditis elegans, gain-of-function mutations in certain ion channel subunits result in the excitotoxic necrosis of six touch neurons and their subsequent engulfment and degradation inside engulfing cells. How necrotic cells are recognized by engulfing cells is unclear. Phosphatidylserine (PS) is an important apoptotic-cell surface signal that attracts engulfing cells. Here we observed PS exposure on the surface of necrotic touch neurons. In addition, the phagocytic receptor CED-1 clusters around necrotic cells and promotes their engulfment. The extracellular domain of CED-1 associates with PS in vitro. We further identified a necrotic cell-specific function of CED-7, a member of the ATP-binding cassette (ABC) transporter family, in promoting PS exposure. In addition to CED-7, anoctamin homolog-1 (ANOH-1), the C. elegans homolog of the mammalian Ca(2+)-dependent phospholipid scramblase TMEM16F, plays an independent role in promoting PS exposure on necrotic cells. The combined activities from CED-7 and ANOH-1 ensure efficient exposure of PS on necrotic cells to attract their phagocytes. In addition, CED-8, the C. elegans homolog of mammalian Xk-related protein 8 also makes a contribution to necrotic cell-removal at the first larval stage. Our work indicates that cells killed by different mechanisms (necrosis or apoptosis) expose a common "eat me" signal to attract their phagocytic receptor(s); furthermore, unlike what was previously believed, necrotic cells actively present PS on their outer surfaces through at least two distinct molecular mechanisms rather than leaking out PS passively.
Collapse
|
32
|
Yang H, Chen YZ, Zhang Y, Wang X, Zhao X, Godfroy JI, Liang Q, Zhang M, Zhang T, Yuan Q, Ann Royal M, Driscoll M, Xia NS, Yin H, Xue D. A lysine-rich motif in the phosphatidylserine receptor PSR-1 mediates recognition and removal of apoptotic cells. Nat Commun 2015; 6:5717. [PMID: 25564762 PMCID: PMC4306451 DOI: 10.1038/ncomms6717] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2014] [Accepted: 10/31/2014] [Indexed: 02/02/2023] Open
Abstract
The conserved phosphatidylserine receptor (PSR) was first identified as a receptor for phosphatidylserine, an "eat-me" signal exposed by apoptotic cells. However, several studies suggest that PSR may also act as an arginine demethylase, a lysyl hydroxylase, or an RNA binding protein through its N-terminal JmjC domain. How PSR might execute drastically different biochemical activities, and whether they are physiologically significant, remain unclear. Here we report that a lysine-rich motif in the extracellular domain of PSR-1, the Caenorhabditis elegans PSR, mediates specific phosphatidylserine binding in vitro and clearance of apoptotic cells in vivo. This motif also mediates phosphatidylserine-induced oligomerization of PSR-1, suggesting a mechanism by which PSR-1 activates phagocytosis. Mutations in the phosphatidylserine-binding motif, but not in its Fe(II) binding site critical for the JmjC activity, abolish PSR-1 phagocytic function. Moreover, PSR-1 enriches and clusters around apoptotic cells during apoptosis. These results establish that PSR-1 is a conserved, phosphatidylserine-recognizing phagocyte receptor.
Collapse
Affiliation(s)
- Hengwen Yang
- Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, Colorado 80309, USA
| | - Yu-Zen Chen
- Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, Colorado 80309, USA
| | - Yi Zhang
- School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Xiaohui Wang
- Department of Chemistry &Biochemistry and BioFrontiers Institute, University of Colorado, Boulder, Colorado 80309, USA
| | - Xiang Zhao
- School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - James I Godfroy
- Department of Chemistry &Biochemistry and BioFrontiers Institute, University of Colorado, Boulder, Colorado 80309, USA
| | - Qian Liang
- School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Man Zhang
- School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Tianying Zhang
- National Institute of Diagnostics and Vaccine Development in Infectious Diseases, Xiamen University, Xiamen 361102, China
| | - Quan Yuan
- National Institute of Diagnostics and Vaccine Development in Infectious Diseases, Xiamen University, Xiamen 361102, China
| | - Mary Ann Royal
- Department of Molecular Biology and Biochemistry, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854, USA
| | - Monica Driscoll
- Department of Molecular Biology and Biochemistry, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854, USA
| | - Ning-Shao Xia
- National Institute of Diagnostics and Vaccine Development in Infectious Diseases, Xiamen University, Xiamen 361102, China
| | - Hang Yin
- 1] Department of Chemistry &Biochemistry and BioFrontiers Institute, University of Colorado, Boulder, Colorado 80309, USA [2] Center of Basic Molecular Science and Department of Chemistry, Tsinghua University, Beijing 100082, China
| | - Ding Xue
- 1] Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, Colorado 80309, USA [2] School of Life Sciences, Tsinghua University, Beijing 100084, China
| |
Collapse
|
33
|
|
34
|
|
35
|
Kodigepalli KM, Bowers K, Sharp A, Nanjundan M. Roles and regulation of phospholipid scramblases. FEBS Lett 2014; 589:3-14. [PMID: 25479087 DOI: 10.1016/j.febslet.2014.11.036] [Citation(s) in RCA: 72] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2014] [Revised: 11/22/2014] [Accepted: 11/24/2014] [Indexed: 02/06/2023]
Abstract
Phospholipid scramblase activity is involved in the collapse of phospholipid (PL) asymmetry at the plasma membrane leading to externalization of phosphatidylserine. This activity is crucial for initiation of the blood coagulation cascade and for recognition/elimination of apoptotic cells by macrophages. Efforts to identify gene products associated with this activity led to the characterization of PL scramblase (PLSCR) and XKR family members which contribute to phosphatidylserine exposure in response to apoptotic stimuli. Meanwhile, TMEM16 family members were identified to externalize phosphatidylserine in response to elevated calcium in Scott syndrome platelets, which is critical for activation of the coagulation cascade. Herein, we report their mechanisms of gene regulation, molecular functions independent of their scrambling activity, and their potential roles in pathogenic conditions.
Collapse
Affiliation(s)
- Karthik M Kodigepalli
- Department of Cell Biology, Microbiology, and Molecular Biology, University of South Florida, Tampa, FL 33620, United States
| | - Kiah Bowers
- Department of Cell Biology, Microbiology, and Molecular Biology, University of South Florida, Tampa, FL 33620, United States
| | - Arielle Sharp
- Department of Cell Biology, Microbiology, and Molecular Biology, University of South Florida, Tampa, FL 33620, United States
| | - Meera Nanjundan
- Department of Cell Biology, Microbiology, and Molecular Biology, University of South Florida, Tampa, FL 33620, United States.
| |
Collapse
|
36
|
Nakagawa A, Sullivan KD, Xue D. Caspase-activated phosphoinositide binding by CNT-1 promotes apoptosis by inhibiting the AKT pathway. Nat Struct Mol Biol 2014; 21:1082-90. [PMID: 25383666 PMCID: PMC4256149 DOI: 10.1038/nsmb.2915] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2014] [Accepted: 10/14/2014] [Indexed: 12/22/2022]
Abstract
Inactivation of cell survival factors is a crucial step in apoptosis. The phosphoinositide 3 kinase (PI3K) and AKT signaling pathway promotes cell growth, proliferation and survival and its deregulation causes cancer. How this pathway is suppressed to promote apoptosis is poorly understood. Here we report the identification of a CED-3 caspase substrate in C. elegans, CNT-1, that upon cleavage by CED-3 during apoptosis activates an N-terminal phosphoinositide-binding fragment (tCNT-1), which translocates from cytoplasm to plasma membrane to block AKT binding to phosphatidylinositol (3,4,5)-triphosphate (PIP3), thereby disabling AKT activation and its pro-survival activity. Our findings reveal a new mechanism that negatively regulates AKT cell signaling to promote apoptosis and that may restrict cell growth and proliferation in normal cells.
Collapse
Affiliation(s)
- Akihisa Nakagawa
- Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, Boulder, Colorado, USA
| | - Kelly D Sullivan
- Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, Boulder, Colorado, USA
| | - Ding Xue
- Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, Boulder, Colorado, USA
| |
Collapse
|
37
|
Treitz C, Cassidy L, Höckendorf A, Leippe M, Tholey A. Quantitative proteome analysis of Caenorhabditis elegans upon exposure to nematicidal Bacillus thuringiensis. J Proteomics 2015; 113:337-50. [PMID: 25452134 DOI: 10.1016/j.jprot.2014.09.027] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2014] [Revised: 08/25/2014] [Accepted: 09/29/2014] [Indexed: 11/21/2022]
Abstract
UNLABELLED Caenorhabditis elegans can be infected by a plethora of pathogens, most of them are also pathogenic for humans. Consequently, the nematode has emerged as a powerful surrogate host to model microbial human infectious diseases in a non-vertebrate, for the study of innate immunity and host-pathogen interactions. Signaling cascades are well investigated that face bacterial or fungal pathogens. We analyzed the downstream processes of these cascades, i.e. the differential expression of effector and regulatory molecules due to a microbial challenge with a pathogenic strain of the bacterium Bacillus thuringiensis (Bt) in comparison to a non-pathogenic Bt strain. The protein abundance profile of the nematode was studied by quantitative proteomics using iTRAQ labeling and 2D-LC-MS analysis. We developed (i) a novel method for the preparation of defined C. elegans samples; (ii) a pooling strategy for fractions in 2D-LC separation schemes; and (iii) an isobaric labeling scheme reducing the number of necessary LC-MS experiments. More than 3,600 proteins were quantified, 288 of which showed altered abundances, implicating protein classes such as lectins, lysozymes, and transthyretin-like proteins to be involved in the nematode innate immune defense. A number of gene products previously only identified by transcriptomic profiling could be verified at the protein level. Moreover, several other protein classes such as proteases, proteins related to autophagy and apoptosis, structural proteins, and proteins involved in chromatin organization were detected. The results provide an overview of the physiological response towards a pathogen at protein level in the important model organism C. elegans, giving insights into highly complex host-pathogen interactions. BIOLOGICAL SIGNIFICANCE This study identified system-wide effects of Bt intoxication on C. elegans at protein level, expanding the catalogue of immune effectors potentially acting towards the pathogen, and provide verification for numerous gene products implicated in previous transcriptomic studies. The data present evidence in support of both a general defense response as well as a specific reaction against the Bt toxin within the nematode. The described findings will also contribute to a deeper understanding of host-microbe interaction in other organisms, including humans, and may provide key information that touches far reaching aspects of coevolutionary processes.
Collapse
|
38
|
Mulinari S, Häcker U. Rho-guanine nucleotide exchange factors during development: Force is nothing without control. Small GTPases 2014; 1:28-43. [PMID: 21686118 DOI: 10.4161/sgtp.1.1.12672] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2010] [Revised: 05/31/2010] [Accepted: 06/14/2010] [Indexed: 01/04/2023] Open
Abstract
The development of multicellular organisms is associated with extensive rearrangements of tissues and cell sheets. The driving force for these rearrangements is generated mostly by the actin cytoskeleton. In order to permit the reproducible development of a specific body plan, dynamic reorganization of the actin cytoskeleton must be precisely coordinated in space and time. GTP-exchange factors that activate small GTPases of the Rho family play an important role in this process. Here we review the role of this class of cytoskeletal regulators during important developmental processes such as epithelial morphogenesis, cytokinesis, cell migration, cell polarity, neuronal growth cone extension and phagocytosis in different model systems.
Collapse
Affiliation(s)
- Shai Mulinari
- Department of Experimental Medical Science; Lund Strategic Research Center for Stem Cell Biology and Cell Therapy; Lund University; Lund, Sweden
| | | |
Collapse
|
39
|
Chen YZ, Mapes J, Lee ES, Skeen-Gaar RR, Xue D. Caspase-mediated activation of Caenorhabditis elegans CED-8 promotes apoptosis and phosphatidylserine externalization. Nat Commun 2013; 4:2726. [PMID: 24225442 DOI: 10.1038/ncomms3726] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2013] [Accepted: 10/08/2013] [Indexed: 02/04/2023] Open
Abstract
During apoptosis, phosphatidylserine (PS), normally restricted to the inner leaflet of the plasma membrane, is exposed on the surface of apoptotic cells and serves as an “eat-me” signal to trigger phagocytosis. It is poorly understood how PS exposure is activated in apoptotic cells. Here we report that CED-8, a C. elegans protein implicated in controlling the kinetics of apoptosis and a homolog of the XK family proteins, is a substrate of the CED-3 caspase. Cleavage of CED-8 by CED-3 activates its proapoptotic function and generates a carboxyl terminal cleavage product, acCED-8, that promotes PS externalization in apoptotic cells and can induce ectopic PS exposure in living cells. Consistent with its role in promoting PS externalization in apoptotic cells, ced-8 is important for cell corpse engulfment in C. elegans. Our finding identifies a crucial link between caspase activation and PS externalization, which triggers phagocytosis of apoptotic cells.
Collapse
|
40
|
Xu M, Liu Y, Zhao L, Gan Q, Wang X, Yang C. The lysosomal cathepsin protease CPL-1 plays a leading role in phagosomal degradation of apoptotic cells in Caenorhabditis elegans. Mol Biol Cell 2014; 25:2071-83. [PMID: 24829385 PMCID: PMC4072580 DOI: 10.1091/mbc.e14-01-0015] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
In Caenorhabditis elegans, the lysosomal cathepsin protease CPL-1 is indispensable for clearance of apoptotic cells by playing a leading role in destruction of cell corpses in phagolysosomes. During programmed cell death, the clearance of apoptotic cells is achieved by their phagocytosis and delivery to lysosomes for destruction in engulfing cells. However, the role of lysosomal proteases in cell corpse destruction is not understood. Here we report the identification of the lysosomal cathepsin CPL-1 as an indispensable protease for apoptotic cell removal in Caenorhabditis elegans. We find that loss of cpl-1 function leads to strong accumulation of germ cell corpses, which results from a failure in degradation rather than engulfment. CPL-1 is expressed in a variety of cell types, including engulfment cells, and its mutation does not affect the maturation of cell corpse–containing phagosomes, including phagosomal recruitment of maturation effectors and phagosome acidification. Of importance, we find that phagosomal recruitment and incorporation of CPL-1 occurs before digestion of cell corpses, which depends on factors required for phagolysosome formation. Using RNA interference, we further examine the role of other candidate lysosomal proteases in cell corpse clearance but find that they do not obviously affect this process. Collectively, these findings establish CPL-1 as the leading lysosomal protease required for elimination of apoptotic cells in C. elegans.
Collapse
Affiliation(s)
- Meng Xu
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, ChinaGraduate University of Chinese Academy of Sciences, Beijing 100109, China
| | - Yubing Liu
- National Institute of Biological Sciences, Beijing 102206, China
| | - Liyuan Zhao
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, ChinaGraduate University of Chinese Academy of Sciences, Beijing 100109, China
| | - Qiwen Gan
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, ChinaGraduate University of Chinese Academy of Sciences, Beijing 100109, China
| | - Xiaochen Wang
- National Institute of Biological Sciences, Beijing 102206, China
| | - Chonglin Yang
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
| |
Collapse
|
41
|
Neukomm LJ, Zeng S, Frei AP, Huegli PA, Hengartner MO. Small GTPase CDC-42 promotes apoptotic cell corpse clearance in response to PAT-2 and CED-1 in C. elegans. Cell Death Differ 2014; 21:845-53. [PMID: 24632947 DOI: 10.1038/cdd.2014.23] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2013] [Revised: 11/27/2013] [Accepted: 12/17/2013] [Indexed: 12/26/2022] Open
Abstract
The rapid clearance of dying cells is important for the well-being of multicellular organisms. In C. elegans, cell corpse removal is mainly mediated by three parallel engulfment signaling cascades. These pathways include two small GTPases, MIG-2/RhoG and CED-10/Rac1. Here we present the identification and characterization of CDC-42 as a third GTPase involved in the regulation of cell corpse clearance. Genetic analyses performed by both loss of cdc-42 function and cdc-42 overexpression place cdc-42 in parallel to the ced-2/5/12 signaling module, in parallel to or upstream of the ced-10 module, and downstream of the ced-1/6/7 module. CDC-42 accumulates in engulfing cells at membranes surrounding apoptotic corpses. The formation of such halos depends on the integrins PAT-2/PAT-3, UNC-112 and the GEF protein UIG-1, but not on the canonical ced-1/6/7 or ced-2/5/12 signaling modules. Together, our results suggest that the small GTPase CDC-42 regulates apoptotic cell engulfment possibly upstream of the canonical Rac GTPase CED-10, by polarizing the engulfing cell toward the apoptotic corpse in response to integrin signaling and ced-1/6/7 signaling in C. elegans.
Collapse
|
42
|
Abstract
Dimethyl sulfoxide (DMSO) is an important aprotic solvent that can solubilize a wide variety of otherwise poorly soluble polar and nonpolar molecules. This, coupled with its apparent low toxicity at concentrations <10%, has led to its ubiquitous use and widespread application. Here, we demonstrate that DMSO induces retinal apoptosis in vivo at low concentrations (5 μl intravitreally dosed DMSO in rat from a stock concentration of 1, 2, 4, and 8% v/v). Toxicity was confirmed in vitro in a retinal neuronal cell line, at DMSO concentrations >1% (v/v), using annexin V, terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL), 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), and AlamarBlue cell viability assays. DMSO concentrations >10% (v/v) have recently been reported to cause cellular toxicity through plasma membrane pore formation. Here, we show the mechanism by which low concentrations (2-4% DMSO) induce caspase-3 independent neuronal death that involves apoptosis-inducing factor (AIF) translocation from mitochondria to the nucleus and poly-(ADP-ribose)-polymerase (PARP) activation. These results highlight safety concerns of using low concentrations of DMSO as a solvent for in vivo administration and in biological assays. We recommend that methods other than DMSO are employed for solubilizing drugs but, where no alternative exists, researchers compute absolute DMSO final concentrations and include an untreated control group in addition to DMSO vehicle control to check for solvent toxicity.
Collapse
Affiliation(s)
- Joana Galvao
- 1Glaucoma and Retinal Neurodegeneration Research Group, Institute of Ophthalmology, University College London, London EC1V 9EL, UK.
| | | | | | | | | | | |
Collapse
|
43
|
Abstract
It has been a long-standing enigma which scramblase causes phosphatidylserine residues to be exposed on the surface of apoptotic cells, thereby facilitating the phagocytic recognition, engulfment and destruction of apoptotic corpses. In a recent paper in Science, Nagata and coworkers reveal that the scramblases Xkr8 and its C. elegans ortholog, CED-8, are activated by caspase cleavage in apoptotic cells.
Collapse
|
44
|
Lant B, Derry WB. Methods for detection and analysis of apoptosis signaling in the C. elegans germline. Methods 2013; 61:174-82. [PMID: 23643851 DOI: 10.1016/j.ymeth.2013.04.022] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2012] [Revised: 04/24/2013] [Accepted: 04/25/2013] [Indexed: 10/26/2022] Open
Abstract
This review assesses current and emerging methods for the detection, and analysis of apoptosis in the Caenorhabditis elegans germline. The nematode worm C. elegans is highly tractable to genetic manipulation, making it an excellent model for elucidating mechanisms of apoptosis signaling in a multicellular setting. Here we profile the most efficacious fluorescent tools to visualize and quantify germline apoptosis. We focus specifically on the application of fluorescent markers to screen by RNAi for genes and pathways that regulate germline apoptosis under normal conditions or in response to genotoxic stress. We also present the limitations of these methods, and suggest complimentary techniques in order that researchers new to the field can comprehensively assess apoptosis phenotypes in the C. elegans germline.
Collapse
Affiliation(s)
- Benjamin Lant
- Developmental & Stem Cell Biology, The Hospital for Sick Children, Toronto, ON, Canada M5G 1X8
| | | |
Collapse
|
45
|
Tung TT, Nagaosa K, Fujita Y, Kita A, Mori H, Okada R, Nonaka S, Nakanishi Y. Phosphatidylserine recognition and induction of apoptotic cell clearance by Drosophila engulfment receptor Draper. ACTA ACUST UNITED AC 2013; 153:483-91. [DOI: 10.1093/jb/mvt014] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
|
46
|
Morton LA, Yang H, Saludes JP, Fiorini Z, Beninson L, Chapman ER, Fleshner M, Xue D, Yin H. MARCKS-ED peptide as a curvature and lipid sensor. ACS Chem Biol 2013; 8:218-25. [PMID: 23075500 DOI: 10.1021/cb300429e] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Membrane curvature and lipid composition regulates important biological processes within a cell. Currently, several proteins have been reported to sense and/or induce membrane curvatures, e.g., Synaptotagmin-1 and Amphiphysin. However, the large protein scaffold of these curvature sensors limits their applications in complex biological systems. Our interest focuses on identifying and designing peptides that can sense membrane curvature based on established elements observed in natural curvature-sensing proteins. Membrane curvature remodeling also depends on their lipid composition, suggesting strategies to specifically target membrane shape and lipid components simultaneously. We have successfully identified a 25-mer peptide, MARCKS-ED, based on the effector domain sequence of the intracellular membrane protein myristoylated alanine-rich C-kinase substrate that can recognize PS with preferences for highly curved vesicles in a sequence-specific manner. These studies further contribute to the understanding of how proteins and peptides sense membrane curvature, as well as provide potential probes for membrane shape and lipid composition.
Collapse
Affiliation(s)
| | | | | | | | | | - Edwin R. Chapman
- Howard
Hughes Medical Institute
and Department of Neuroscience, University of Wisconsin, Madison, Wisconsin 53706, United States
| | | | | | | |
Collapse
|
47
|
Abstract
The nematode Caenorhabditis elegans is an excellent model organism for studying the mechanisms -controlling cell death, including apoptosis, a cell suicide event, and necrosis, pathological cell deaths caused by environmental insults or genetic alterations. C. elegans has also been established as a model for understanding how dying cells are cleared from animal bodies. In particular, the transparent nature of worm bodies and eggshells make C. elegans particularly amenable for live-cell microscopy. Here we describe methods for identifying apoptotic and necrotic cells in living C. elegans embryos, larvae, and adults and for monitoring their clearance during development. We further discuss specific methods to distinguish engulfed from unengulfed apoptotic cells, and methods to monitor cellular and molecular events occurring during phagosome maturation. These methods are based on Differential Interference Contrast (DIC) microscopy or fluorescence microscopy using GFP-based reporters.
Collapse
Affiliation(s)
- Zao Li
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX, USA
| | | | | | | |
Collapse
|
48
|
Huang J, Wang H, Chen Y, Wang X, Zhang H. Residual body removal during spermatogenesis in C. elegans requires genes that mediate cell corpse clearance. Development 2012; 139:4613-22. [PMID: 23172915 PMCID: PMC3509724 DOI: 10.1242/dev.086769] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/21/2012] [Indexed: 12/20/2022]
Abstract
Generation of spermatozoa involves segregation of most of the cytoplasm into residual bodies, which are detached from spermatids and eliminated in mammals. However, the molecular and cellular mechanism underlying the removal of residual bodies remains largely unknown. Here, we demonstrate that during C. elegans spermatogenesis residual bodies are engulfed and degraded by gonadal sheath cells, a process that uses the same set of genes underlying apoptotic cell removal. The two partially redundant engulfment pathways that clear cell corpses also mediate phagocytosis of residual bodies, possibly by recognizing the 'eat me' signal phosphatidylserine exposed on the surface. The residual body-containing phagosome undergoes a maturation process involving sequential steps including dynamic coating with PtdIns(3)P and association of RAB small GTPases. The genetic hierarchy of residual body removal in hermaphrodites is similar to that of cell corpse clearance, but male residual body removal involves a distinct hierarchy, with differential use of the engulfment genes. Efficient removal of residual bodies regulates the number of spermatids and effective transfer of spermatids during male matings. Our results indicate that a similar molecular mechanism is employed for the removal of residual bodies and apoptotic cell corpses in C. elegans.
Collapse
Affiliation(s)
- Jie Huang
- State Key Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, P.R. China
- Key Laboratory of Medical Immunology, Ministry of Health, Peking University Health Science Center, Beijing, 100191, P.R. China
| | - Haibin Wang
- College of Life Sciences, China Agricultural University, Beijing, 100094, P.R. China
- National Institute of Biological Sciences, Beijing, 102206, P.R. China
| | - Yingyu Chen
- Key Laboratory of Medical Immunology, Ministry of Health, Peking University Health Science Center, Beijing, 100191, P.R. China
| | - Xiaochen Wang
- National Institute of Biological Sciences, Beijing, 102206, P.R. China
| | - Hong Zhang
- State Key Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, P.R. China
- National Institute of Biological Sciences, Beijing, 102206, P.R. China
| |
Collapse
|
49
|
Abstract
Genetic and cell biology studies have led to the identification in Caenorhabditis elegans of a set of evolutionary conserved cellular mechanisms responsible for the clearance of apoptotic cells. Based on the phenotype of cell corpse clearance mutants, corpse clearance can be divided into three distinct, but linked steps: corpse recognition, corpse internalization, and corpse degradation. Work in recent years has led to a better understanding of the molecular pathways that mediate each of these steps. Here, we review recent developments in our understanding of in vivo cell corpse clearance in this simple but most elegant model organism.
Collapse
Affiliation(s)
- Sérgio Morgado Pinto
- Institute of Molecular Life Sciences, University of Zurich, 8057 Zurich, Switzerland; Graduate Program in Areas of Basic and Applied Biology (GABBA), Universidade do Porto, Porto, Portugal
| | | |
Collapse
|
50
|
Preta G, Fadeel B. AIF and Scythe (Bat3) regulate phosphatidylserine exposure and macrophage clearance of cells undergoing Fas (APO-1)-mediated apoptosis. PLoS One 2012; 7:e47328. [PMID: 23077592 PMCID: PMC3471829 DOI: 10.1371/journal.pone.0047328] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2012] [Accepted: 09/12/2012] [Indexed: 11/18/2022] Open
Abstract
Phosphatidylserine (PS) exposure on the cell surface has been considered a characteristic feature of apoptosis and serves as a molecular cue for engulfment of dying cells by phagocytes. However, the mechanism of PS exposure is still not fully elucidated. Here we show that the cytosolic release from mitochondria of apoptosis-inducing factor (AIF) is required for PS exposure during death receptor-induced apoptosis and for efficient clearance of cell corpses by primary human macrophages. Fas-triggered PS exposure was significantly reduced upon siRNA-mediated silencing of AIF expression and by inhibition of the cytosolic translocation of AIF. In addition, AIF localizes to the plasma membrane upon Fas ligation and promotes activation of phospholipid scrambling activity. Finally, cytosolic stabilization of AIF through interaction with Scythe is shown to be involved in apoptotic PS exposure. Taken together, our results suggest an essential role for AIF and its binding partner Scythe in the pathway leading to apoptotic corpse clearance.
Collapse
Affiliation(s)
- Giulio Preta
- Division of Molecular Toxicology, Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden
| | - Bengt Fadeel
- Division of Molecular Toxicology, Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden
- * E-mail:
| |
Collapse
|