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Su Y, Shea J, DeStephanis D, Su Z. Transcriptomic Analysis of the Spatiotemporal Axis of Oogenesis and Fertilization in C. elegans. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.03.597235. [PMID: 38895354 PMCID: PMC11185608 DOI: 10.1101/2024.06.03.597235] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/21/2024]
Abstract
The oocyte germline of the C. elegans hermaphrodite presents a unique model to study the formation of oocytes. However, the size of the model animal and difficulties in retrieval of specific stages of the germline have obviated closer systematic studies of this process throughout the years. Here, we present a transcriptomic level analysis into the oogenesis of C. elegans hermaphrodites. We dissected a hermaphrodite gonad into seven sections corresponding to the mitotic distal region, the pachytene, the diplotene, the early diakinesis region and the 3 most proximal oocytes, and deeply sequenced the transcriptome of each of them along with that of the fertilized egg using a single-cell RNA-seq protocol. We identified specific gene expression events as well as gene splicing events in finer detail along the oocyte germline and provided novel insights into underlying mechanisms of the oogenesis process. Furthermore, through careful review of relevant research literature coupled with patterns observed in our analysis, we attempt to delineate transcripts that may serve functions in the interaction between the germline and cells of the somatic gonad. These results expand our knowledge of the transcriptomic space of the C. elegans germline and lay a foundation on which future studies of the germline can be based upon.
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Wu Z, Cardona EA, Pierce JT. Non-apoptotic role of EGL-1 in exopher production and neuronal health in Caenorhabditis elegans. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 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] [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.
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Neverov AM, Panchin AY, Mikhailov KV, Batueva MD, Aleoshin VV, Panchin YV. Apoptotic gene loss in Cnidaria is associated with transition to parasitism. Sci Rep 2023; 13:8015. [PMID: 37198195 DOI: 10.1038/s41598-023-34248-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2022] [Accepted: 04/26/2023] [Indexed: 05/19/2023] Open
Abstract
The phylum Cnidaria consists of several morphologically diverse classes including Anthozoa, Cubozoa, Hydrozoa, Polypodiozoa, Scyphozoa, Staurozoa, and Myxozoa. Myxozoa comprises two subclasses of obligate parasites-Myxosporea and Malacosporea, which demonstrate various degrees of simplification. Myxosporea were previously reported to lack the majority of core protein domains of apoptotic proteins including caspases, Bcl-2, and APAF-1 homologs. Other sequenced Cnidaria, including the parasite Polypodium hydriforme from Polypodiozoa do not share this genetic feature. Whether this loss of core apoptotic proteins is unique to Myxosporea or also present in its sister subclass Malacosporea was not previously investigated. We show that the presence of core apoptotic proteins gradually diminishes from free-living Cnidaria to Polypodium to Malacosporea to Myxosporea. This observation does not favor the hypothesis of catastrophic simplification of Myxosporea at the genetic level, but rather supports a stepwise adaptation to parasitism that likely started from early parasitic ancestors that gave rise to Myxozoa.
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Affiliation(s)
- Alexander M Neverov
- Department of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow, Russian Federation, 119234.
| | - Alexander Y Panchin
- Kharkevich Institute for Information Transmission Problems, Russian Academy of Sciences, Moscow, Russian Federation, 127994
| | - Kirill V Mikhailov
- Kharkevich Institute for Information Transmission Problems, Russian Academy of Sciences, Moscow, Russian Federation, 127994
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Leninskiye Gory 1-40, Moscow, Russian Federation, 119991
| | - Marina D Batueva
- Institute of General and Experimental Biology Siberian Branch of Russian Academy of Sciences, Ulan-Ude, Russian Federation, 670047
| | - Vladimir V Aleoshin
- Kharkevich Institute for Information Transmission Problems, Russian Academy of Sciences, Moscow, Russian Federation, 127994
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Leninskiye Gory 1-40, Moscow, Russian Federation, 119991
| | - Yuri V Panchin
- Kharkevich Institute for Information Transmission Problems, Russian Academy of Sciences, Moscow, Russian Federation, 127994
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Leninskiye Gory 1-40, Moscow, Russian Federation, 119991
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4
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Wang Y, Wu W, Gong J. Live or death in cells: from micronutrition metabolism to cell fate. Front Cell Dev Biol 2023; 11:1185989. [PMID: 37250891 PMCID: PMC10213646 DOI: 10.3389/fcell.2023.1185989] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Accepted: 04/28/2023] [Indexed: 05/31/2023] Open
Abstract
Micronutrients and cell death have a strong relationship and both are essential for human to maintain good body health. Dysregulation of any micronutrients causes metabolic or chronic diseases, including obesity, cardiometabolic condition, neurodegeneration, and cancer. The nematode Caenorhabditis elegans is an ideal genetic organism for researching the mechanisms of micronutrients in metabolism, healthspan, and lifespan. For example, C. elegans is a haem auxotroph, and the research of this special haem trafficking pathway contributes important reference to mammal study. Also, C. elegans characteristics including anatomy simply, clear cell lineage, well-defined genetics, and easily differentiated cell forms make it a powerful tool for studying the mechanisms of cell death including apoptosis, necrosis, autophagy, and ferroptosis. Here, we describe the understanding of micronutrient metabolism currently and also sort out the fundamental mechanisms of different kinds of cell death. A thorough understanding of these physiological processes not only builds a foundation for developing better treatments for various micronutrient disorders but also provides key insights into human health and aging.
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Affiliation(s)
- Yuting Wang
- Key Laboratory of Molecular Biophysics of MOE, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Wei Wu
- State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, National Clinical Research Center for Infectious Diseases, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, China
| | - Jianke Gong
- Key Laboratory of Molecular Biophysics of MOE, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei, China
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5
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Furuta Y, Zhou Z. How do necrotic cells expose phosphatidylserine to attract their predators—What’s unique and what’s in common with apoptotic cells. Front Cell Dev Biol 2023; 11:1170551. [PMID: 37091984 PMCID: PMC10113483 DOI: 10.3389/fcell.2023.1170551] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Accepted: 03/27/2023] [Indexed: 04/09/2023] Open
Abstract
Phosphatidylserine (PS) is a lipid component of the plasma membrane. It is asymmetrically distributed to the inner leaflet in live cells. In cells undergoing apoptosis, phosphatidylserine is exposed to the outer surfaces. The exposed phosphatidylserine acts as an evolutionarily conserved “eat-me” signal that attracts neighboring engulfing cells in metazoan organisms, including the nematode Caenorhabditis elegans, the fruit fly Drosophila melanogaster, and mammals. During apoptosis, the exposure of phosphatidylserine to the outer surface of a cell is driven by the membrane scramblases and flippases, the activities of which are regulated by caspases. Cells undergoing necrosis, a kind of cell death frequently associated with cellular injuries and morphologically distinct from apoptosis, were initially believed to allow passive exposure of phosphatidylserine through membrane rupture. Later studies revealed that necrotic cells actively expose phosphatidylserine before any rupture occurs. A recent study in C. elegans further reported that the calcium ion (Ca2+) plays an essential role in promoting the exposure of phosphatidylserine on the surfaces of necrotic cells. These findings indicate that necrotic and apoptotic cells, which die through different molecular mechanisms, use common and unique mechanisms for promoting the exposure of the same “eat me” signal. This article will review the mechanisms regulating the exposure of phosphatidylserine on the surfaces of necrotic and apoptotic cells and highlight their similarities and differences.
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6
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Lo CF, Chiu TY, Liu YT, Pan PY, Liu KL, Hsu CY, Fang MY, Huang YC, Yeh TK, Hsu TA, Chen CT, Huang LR, Tsou LK. Targeting the Phosphatidylserine-Immune Checkpoint with a Small-Molecule Maytansinoid Conjugate. J Med Chem 2022; 65:12802-12824. [PMID: 36153998 PMCID: PMC9574934 DOI: 10.1021/acs.jmedchem.2c00631] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
![]()
Ligand-targeting drug delivery systems have made significant
strides
for disease treatments with numerous clinical approvals in this era
of precision medicine. Herein, we report a class of small molecule-based
immune checkpoint-targeting maytansinoid conjugates. From the ligand
targeting ability, pharmacokinetics profiling, in vivo anti-pancreatic cancer, triple-negative breast cancer, and sorafenib-resistant
liver cancer efficacies with quantitative mRNA analysis of treated-tumor
tissues, we demonstrated that conjugate 40a not only
induced lasting regression of tumor growth, but it also rejuvenated
the once immunosuppressive tumor microenvironment to an “inflamed
hot tumor” with significant elevation of gene expressions that
were not accessible in the vehicle-treated tumor. In turn, the immune
checkpoint-targeting small molecule drug conjugate from this work
represents a new pharmacodelivery strategy that can be expanded with
combination therapy with existing immune-oncology treatment options.
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Affiliation(s)
- Chen-Fu Lo
- Institute of Biotechnology and Pharmaceutical Research, National Health Research Institutes, Miaoli35053, Taiwan, ROC
| | - Tai-Yu Chiu
- Institute of Biotechnology and Pharmaceutical Research, National Health Research Institutes, Miaoli35053, Taiwan, ROC
| | - Yu-Tzu Liu
- Institute of Molecular and Genomic Medicine, National Health Research Institutes, Miaoli35053, Taiwan, ROC
| | - Pei-Yun Pan
- Institute of Biotechnology and Pharmaceutical Research, National Health Research Institutes, Miaoli35053, Taiwan, ROC
| | - Kuan-Liang Liu
- Institute of Biotechnology and Pharmaceutical Research, National Health Research Institutes, Miaoli35053, Taiwan, ROC
| | - Chia-Yu Hsu
- Institute of Biotechnology and Pharmaceutical Research, National Health Research Institutes, Miaoli35053, Taiwan, ROC
| | - Ming-Yu Fang
- Institute of Biotechnology and Pharmaceutical Research, National Health Research Institutes, Miaoli35053, Taiwan, ROC
| | - Yu-Chen Huang
- Institute of Biotechnology and Pharmaceutical Research, National Health Research Institutes, Miaoli35053, Taiwan, ROC
| | - Teng-Kuang Yeh
- Institute of Biotechnology and Pharmaceutical Research, National Health Research Institutes, Miaoli35053, Taiwan, ROC
| | - Tsu-An Hsu
- Institute of Biotechnology and Pharmaceutical Research, National Health Research Institutes, Miaoli35053, Taiwan, ROC
| | - Chiung-Tong Chen
- Institute of Biotechnology and Pharmaceutical Research, National Health Research Institutes, Miaoli35053, Taiwan, ROC
| | - Li-Rung Huang
- Institute of Molecular and Genomic Medicine, National Health Research Institutes, Miaoli35053, Taiwan, ROC
| | - Lun Kelvin Tsou
- Institute of Biotechnology and Pharmaceutical Research, National Health Research Institutes, Miaoli35053, Taiwan, ROC
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7
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Yuan L, Li P, Zheng Q, Wang H, Xiao H. The Ubiquitin-Proteasome System in Apoptosis and Apoptotic Cell Clearance. Front Cell Dev Biol 2022; 10:914288. [PMID: 35874820 PMCID: PMC9300945 DOI: 10.3389/fcell.2022.914288] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Accepted: 06/16/2022] [Indexed: 12/30/2022] Open
Abstract
Ubiquitination, a critical post-translational modification of proteins, refers to the covalent attachment of ubiquitin to the substrate and is involved in various biological processes such as protein stability regulation, DNA damage repair, and apoptosis, among others. E3 ubiquitin ligases are essential enzymes of the ubiquitin pathway with high substrate specificity and precisely regulate specific proteins’ turnover. As one of the most well-studied forms of programmed cell death, apoptosis is substantially conserved across the evolutionary tree. The final critical stage in apoptosis is the removal of apoptotic cells by professional and non-professional phagocytes. Apoptosis and apoptotic cell clearance are crucial for the normal development, differentiation, and growth of multicellular organisms, as well as their association with a variety of inflammatory and immune diseases. In this review, we discuss the role of ubiquitination and deubiquitination in apoptosis and apoptotic cell clearance.
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Affiliation(s)
- Lei Yuan
- College of Life Sciences, Shaanxi Normal University, Xi'an, China
| | - Peiyao Li
- College of Life Sciences, Shaanxi Normal University, Xi'an, China
| | - Qian Zheng
- College of Life Sciences, Shaanxi Normal University, Xi'an, China
| | - Hui Wang
- College of Life Sciences, Shaanxi Normal University, Xi'an, China
| | - Hui Xiao
- College of Life Sciences, Shaanxi Normal University, Xi'an, China
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8
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Ji H, Yu Z, He L, Zhu J, Cao X, Song X. Programmed cell death induced by modified clay in controlling Prorocentrum donghaiense bloom. J Environ Sci (China) 2021; 109:123-134. [PMID: 34607661 DOI: 10.1016/j.jes.2021.03.039] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Revised: 03/24/2021] [Accepted: 03/24/2021] [Indexed: 06/13/2023]
Abstract
Modified clay (MC), an effective material used for the emergency elimination of algal blooms, can rapidly reduce the biomass of harmful algal blooms (HABs) via flocculation. After that, MC can still control bloom population through indirect effects such as oxidative stress, which was initially proposed to be related to programmed cell death (PCD) at molecular level. To further study the MC induced cell death in residual bloom organisms, especially identifying PCD process, we studied the physiological state of the residual Prorocentrum donghaiense. The experimental results showed that flocculation changed the physiological state of the residual cells, as evidenced by growth inhibition and increased reactive oxygen species production. Moreover, this research provides biochemical and ultrastructural evidence showing that MC induces PCD in P. donghaiense. Nuclear changes were observed, and increased caspase-like activity, externalization of phosphatidylserine and DNA fragmentation were detected in MC-treated groups and quantified. And the mitochondrial apoptosis pathway was activated in both MC-treated groups. Besides, the features of MC-induced PCD in a unicellular organism were summarized and its concentration dependent manner was proved. All our preliminary results elucidate the mechanism through which MC can further control HABs by inducing PCD and suggest a promising application of PCD in bloom control.
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Affiliation(s)
- Hena Ji
- CAS Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China; Laboratory of Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266237, China; University of Chinese Academy of Sciences, Beijing 100049, China; Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao 266071, China
| | - Zhiming Yu
- CAS Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China; Laboratory of Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266237, China; University of Chinese Academy of Sciences, Beijing 100049, China; Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao 266071, China.
| | - Liyan He
- CAS Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China; Laboratory of Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266237, China; Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao 266071, China
| | - Jianan Zhu
- CAS Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China; Laboratory of Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266237, China; Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao 266071, China
| | - Xihua Cao
- CAS Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China; Laboratory of Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266237, China; Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao 266071, China
| | - Xiuxian Song
- CAS Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China; Laboratory of Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266237, China; University of Chinese Academy of Sciences, Beijing 100049, China; Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao 266071, China
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9
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Straub MS, Alvadia C, Sawicka M, Dutzler R. Cryo-EM structures of the caspase-activated protein XKR9 involved in apoptotic lipid scrambling. eLife 2021; 10:e69800. [PMID: 34263724 PMCID: PMC8298096 DOI: 10.7554/elife.69800] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Accepted: 07/11/2021] [Indexed: 12/17/2022] Open
Abstract
The exposure of the negatively charged lipid phosphatidylserine on the cell surface, catalyzed by lipid scramblases, is an important signal for the clearance of apoptotic cells by macrophages. The protein XKR9 is a member of a conserved family that has been associated with apoptotic lipid scrambling. Here, we describe structures of full-length and caspase-treated XKR9 from Rattus norvegicus in complex with a synthetic nanobody determined by cryo-electron microscopy. The 43 kDa monomeric membrane protein can be divided into two structurally related repeats, each containing four membrane-spanning segments and a helix that is partly inserted into the lipid bilayer. In the full-length protein, the C-terminus interacts with a hydrophobic pocket located at the intracellular side acting as an inhibitor of protein function. Cleavage by caspase-3 at a specific site releases 16 residues of the C-terminus, thus making the pocket accessible to the cytoplasm. Collectively, the work has revealed the unknown architecture of the XKR family and has provided initial insight into its activation by caspases.
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Affiliation(s)
- Monique S Straub
- Department of Biochemistry, University of ZurichZurichSwitzerland
| | - Carolina Alvadia
- Department of Biochemistry, University of ZurichZurichSwitzerland
| | - Marta Sawicka
- Department of Biochemistry, University of ZurichZurichSwitzerland
| | - Raimund Dutzler
- Department of Biochemistry, University of ZurichZurichSwitzerland
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10
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Having an Old Friend for Dinner: The Interplay between Apoptotic Cells and Efferocytes. Cells 2021; 10:cells10051265. [PMID: 34065321 PMCID: PMC8161178 DOI: 10.3390/cells10051265] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Revised: 05/12/2021] [Accepted: 05/17/2021] [Indexed: 02/02/2023] Open
Abstract
Apoptosis, the programmed and intentional death of senescent, damaged, or otherwise superfluous cells, is the natural end-point for most cells within multicellular organisms. Apoptotic cells are not inherently damaging, but if left unattended, they can lyse through secondary necrosis. The resulting release of intracellular contents drives inflammation in the surrounding tissue and can lead to autoimmunity. These negative consequences of secondary necrosis are avoided by efferocytosis—the phagocytic clearance of apoptotic cells. Efferocytosis is a product of both apoptotic cells and efferocyte mechanisms, which cooperate to ensure the rapid and complete removal of apoptotic cells. Herein, we review the processes used by apoptotic cells to ensure their timely removal, and the receptors, signaling, and cellular processes used by efferocytes for efferocytosis, with a focus on the receptors and signaling driving this process.
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11
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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] [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.
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12
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Furuta Y, Pena-Ramos O, Li Z, Chiao L, Zhou Z. Calcium ions trigger the exposure of phosphatidylserine on the surface of necrotic cells. PLoS Genet 2021; 17:e1009066. [PMID: 33571185 PMCID: PMC7904182 DOI: 10.1371/journal.pgen.1009066] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2020] [Revised: 02/24/2021] [Accepted: 01/18/2021] [Indexed: 11/18/2022] Open
Abstract
Intracellular Ca2+ level is under strict regulation through calcium channels and storage pools including the endoplasmic reticulum (ER). Mutations in certain ion channel subunits, which cause mis-regulated Ca2+ influx, induce the excitotoxic necrosis of neurons. In the nematode Caenorhabditis elegans, dominant mutations in the DEG/ENaC sodium channel subunit MEC-4 induce six mechanosensory (touch) neurons to undergo excitotoxic necrosis. These necrotic neurons are subsequently engulfed and digested by neighboring hypodermal cells. We previously reported that necrotic touch neurons actively expose phosphatidylserine (PS), an “eat-me” signal, to attract engulfing cells. However, the upstream signal that triggers PS externalization remained elusive. Here we report that a robust and transient increase of cytoplasmic Ca2+ level occurs prior to the exposure of PS on necrotic touch neurons. Inhibiting the release of Ca2+ from the ER, either pharmacologically or genetically, specifically impairs PS exposure on necrotic but not apoptotic cells. On the contrary, inhibiting the reuptake of cytoplasmic Ca2+ into the ER induces ectopic necrosis and PS exposure. Remarkably, PS exposure occurs independently of other necrosis events. Furthermore, unlike in mutants of DEG/ENaC channels, in dominant mutants of deg-3 and trp-4, which encode Ca2+ channels, PS exposure on necrotic neurons does not rely on the ER Ca2+ pool. Our findings indicate that high levels of cytoplasmic Ca2+ are necessary and sufficient for PS exposure. They further reveal two Ca2+-dependent, necrosis-specific pathways that promote PS exposure, a “two-step” pathway initiated by a modest influx of Ca2+ and further boosted by the release of Ca2+ from the ER, and another, ER-independent, pathway. Moreover, we found that ANOH-1, the worm homolog of mammalian phospholipid scramblase TMEM16F, is necessary for efficient PS exposure in thapsgargin-treated worms and trp-4 mutants, like in mec-4 mutants. We propose that both the ER-mediated and ER-independent Ca2+ pathways promote PS externalization through activating ANOH-1. Necrosis is a type of cell death that exhibits distinct morphological features such as cell and organelle swelling. Necrotic cells expose phosphatidylserine (PS)–a type of phospholipid—on their outer surfaces. Receptor molecules on phagocytes detect PS on necrotic cells and subsequently initiate the engulfment process. As necrosis is associated with stroke, cancer, neurodegenerative diseases, and heart diseases, studying necrotic cell clearance has important medical relevance. In the model organism the nematode C. elegans, we previously identified membrane proteins that promote the exposure of PS on necrotic cell surfaces by studying neurons that are induced to undergo necrosis by dominant mutations in ion channels. Here, in C. elegans, we have discovered that the necrotic insults trigger an increase of the cytoplasmic calcium ion (Ca2+), which in turn promotes PS externalization on necrotic cell surfaces. Furthermore, we have identified two different mechanisms that increase cytoplasmic Ca2+ levels, one dependent on the Ca2+ contribution from the endoplasmic reticulum (ER), the other independent of the ER. The Ca2+ signal targets ANOH-1, a worm homolog of mammalian proteins capable of externalizing PS, for promoting PS exposure on necrotic cells. Our findings reveal novel upstream regulatory mechanisms that promote necrotic cell clearance in animals.
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Affiliation(s)
- Yoshitaka Furuta
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas, United States of America
- School of Pharmacy, Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa, Japan
| | - Omar Pena-Ramos
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Zao Li
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Lucia Chiao
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Zheng Zhou
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas, United States of America
- * E-mail:
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13
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Li P, Jing H, Wang Y, Yuan L, Xiao H, Zheng Q. SUMO modification in apoptosis. J Mol Histol 2020; 52:1-10. [PMID: 33225418 PMCID: PMC7790789 DOI: 10.1007/s10735-020-09924-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Accepted: 10/23/2020] [Indexed: 12/15/2022]
Abstract
Apoptosis and clearance of dead cells is highly evolutionarily conserved from nematode to humans, which is crucial to the growth and development of multicellular organism. Fail to remove apoptotic cells often lead to homeostasis imbalance, fatal autoimmune diseases, and neurodegenerative diseases. Small ubiquitin-related modifiers (SUMOs) modification is a post-translational modification of ubiquitin proteins mediated by the sentrin-specific proteases (SENPs) family. SUMO modification is widely involved in many cellular biological process, and abnormal SUMO modification is also closely related to many major human diseases. Recent researches have revealed that SUMO modification event occurs during apoptosis and clearance of apoptotic cells, and plays an important role in the regulation of apoptotic signaling pathways. This review summarizes some recent progress in the revelation of regulatory mechanisms of these pathways and provides some potential researching hotpots of the SUMO modification regulation to apoptosis.
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Affiliation(s)
- Peiyao Li
- Key Laboratory of the Ministry of Education for Medicinal Plant Resources and Natural Pharmaceutical Chemistry, National Engineering Laboratory for Resource Development of Endangered Crude Drugs in the Northwest of China, College of Life Sciences, Shaanxi Normal University, Xi'an, 710119, China
| | - Huiru Jing
- Key Laboratory of the Ministry of Education for Medicinal Plant Resources and Natural Pharmaceutical Chemistry, National Engineering Laboratory for Resource Development of Endangered Crude Drugs in the Northwest of China, College of Life Sciences, Shaanxi Normal University, Xi'an, 710119, China
| | - Yanzhe Wang
- Key Laboratory of the Ministry of Education for Medicinal Plant Resources and Natural Pharmaceutical Chemistry, National Engineering Laboratory for Resource Development of Endangered Crude Drugs in the Northwest of China, College of Life Sciences, Shaanxi Normal University, Xi'an, 710119, China
| | - Lei Yuan
- Key Laboratory of the Ministry of Education for Medicinal Plant Resources and Natural Pharmaceutical Chemistry, National Engineering Laboratory for Resource Development of Endangered Crude Drugs in the Northwest of China, College of Life Sciences, Shaanxi Normal University, Xi'an, 710119, China
| | - Hui Xiao
- Key Laboratory of the Ministry of Education for Medicinal Plant Resources and Natural Pharmaceutical Chemistry, National Engineering Laboratory for Resource Development of Endangered Crude Drugs in the Northwest of China, College of Life Sciences, Shaanxi Normal University, Xi'an, 710119, China
| | - Qian Zheng
- Key Laboratory of the Ministry of Education for Medicinal Plant Resources and Natural Pharmaceutical Chemistry, National Engineering Laboratory for Resource Development of Endangered Crude Drugs in the Northwest of China, College of Life Sciences, Shaanxi Normal University, Xi'an, 710119, China.
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14
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Ghose P, Wehman AM. The developmental and physiological roles of phagocytosis in Caenorhabditis elegans. Curr Top Dev Biol 2020; 144:409-432. [PMID: 33992160 DOI: 10.1016/bs.ctdb.2020.09.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
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.
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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.
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15
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Recent Advances in the Genetic, Anatomical, and Environmental Regulation of the C. elegans Germ Line Progenitor Zone. J Dev Biol 2020; 8:jdb8030014. [PMID: 32707774 PMCID: PMC7559772 DOI: 10.3390/jdb8030014] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2020] [Revised: 07/13/2020] [Accepted: 07/15/2020] [Indexed: 12/16/2022] Open
Abstract
The C. elegans germ line and its gonadal support cells are well studied from a developmental genetics standpoint and have revealed many foundational principles of stem cell niche biology. Among these are the observations that a niche-like cell supports a self-renewing stem cell population with multipotential, differentiating daughter cells. While genetic features that distinguish stem-like cells from their differentiating progeny have been defined, the mechanisms that structure these populations in the germ line have yet to be explained. The spatial restriction of Notch activation has emerged as an important genetic principle acting in the distal germ line. Synthesizing recent findings, I present a model in which the germ stem cell population of the C. elegans adult hermaphrodite can be recognized as two distinct anatomical and genetic populations. This review describes the recent progress that has been made in characterizing the undifferentiated germ cells and gonad anatomy, and presents open questions in the field and new directions for research to pursue.
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16
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Affiliation(s)
- Hye-Won Shin
- Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, Japan
| | - Hiroyuki Takatsu
- Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, Japan
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17
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Galle JN, Hegemann JH. Exofacial phospholipids at the plasma membrane: ill-defined targets for early infection processes. Biol Chem 2020; 400:1323-1334. [PMID: 31408428 DOI: 10.1515/hsz-2019-0187] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Accepted: 08/06/2019] [Indexed: 02/04/2023]
Abstract
The eukaryotic plasma membrane (PM) consists largely of phospholipids and proteins, and separates the intracellular compartments from the extracellular space. It also serves as a signaling platform for cell-to-cell communication and an interaction platform for the molecular crosstalk between pathogens and their target cells. Much research has been done to elucidate the interactions between pathogens and host membrane proteins. However, little is known about the interactions between pathogens and membrane phospholipids, although reports have described a contribution of phospholipids to cell recognition and/or invasion during early infection by diverse pathogens. Thus, during adhesion to the host cell, the obligate intracellular bacterial pathogens Chlamydia spp., the facultative intracellular pathogen Helicobacter pylori and the facultative aerobic pathogen Vibrio parahaemolyticus, interact with exofacial phospholipids. This review focuses on several prominent instances of pathogen interaction with host-cell phospholipids.
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Affiliation(s)
- Jan N Galle
- Lehrstuhl für Funktionelle Genomforschung der Mikroorganismen, Heinrich-Heine-Universität Düsseldorf, Universitätsstraße 1, D-40225 Düsseldorf, Germany
| | - Johannes H Hegemann
- Lehrstuhl für Funktionelle Genomforschung der Mikroorganismen, Heinrich-Heine-Universität Düsseldorf, Universitätsstraße 1, D-40225 Düsseldorf, Germany
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18
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Stabilin Receptors: Role as Phosphatidylserine Receptors. Biomolecules 2019; 9:biom9080387. [PMID: 31434355 PMCID: PMC6723754 DOI: 10.3390/biom9080387] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2019] [Revised: 08/16/2019] [Accepted: 08/18/2019] [Indexed: 12/18/2022] Open
Abstract
Phosphatidylserine is a membrane phospholipid that is localized to the inner leaflet of the plasma membrane. Phosphatidylserine externalization to the outer leaflet of the plasma membrane is an important signal for various physiological processes, including apoptosis, platelet activation, cell fusion, lymphocyte activation, and regenerative axonal fusion. Stabilin-1 and stabilin-2 are membrane receptors that recognize phosphatidylserine on the cell surface. Here, we discuss the functions of Stabilin-1 and stabilin-2 as phosphatidylserine receptors in apoptotic cell clearance (efferocytosis) and cell fusion, and their ligand-recognition and signaling pathways.
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19
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Liu YW, Chen YY, Hsu CY, Chiu TY, Liu KL, Lo CF, Fang MY, Huang YC, Yeh TK, Pak KY, Gray BD, Hsu TA, Huang KH, Shih C, Shia KS, Chen CT, Tsou LK. Linker Optimization and Therapeutic Evaluation of Phosphatidylserine-Targeting Zinc Dipicolylamine-based Drug Conjugates. J Med Chem 2019; 62:6047-6062. [PMID: 31181158 DOI: 10.1021/acs.jmedchem.9b00173] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
We report that compound 13, a novel phosphatidylserine-targeting zinc(II) dipicolylamine drug conjugate, readily triggers a positive feedback therapeutic loop through the in situ generation of phosphatidylserine in the tumor microenvironment. Linker modifications, pharmacokinetics profiling, in vivo antitumor studies, and micro-Western array of treated-tumor tissues were employed to show that this class of conjugates induced regeneration of apoptotic signals, which facilitated subsequent recruitment of the circulating conjugates through the zinc(II) dipicolylamine-phosphatidylserine association and resulted in compounding antitumor efficacy. Compared to the marketed compound 17, compound 13 not only induced regressions in colorectal and pancreatic tumor models, it also exhibited at least 5-fold enhancement in antitumor efficacy with only 40% of the drug employed during treatment, culminating in a >12.5-fold increase in therapeutic potential. Our study discloses a chemically distinct apoptosis-targeting theranostic, with built-in complementary functional moieties between the targeting module and the drug mechanism to expand the arsenal of antitumor therapy.
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Affiliation(s)
- Yu-Wei Liu
- Institute of Biotechnology and Pharmaceutical Research , National Health Research Institutes , Miaoli 35053 , Taiwan , ROC
| | - Yun-Yu Chen
- Institute of Biotechnology and Pharmaceutical Research , National Health Research Institutes , Miaoli 35053 , Taiwan , ROC
| | - Chia-Yu Hsu
- Institute of Biotechnology and Pharmaceutical Research , National Health Research Institutes , Miaoli 35053 , Taiwan , ROC
| | - Tai-Yu Chiu
- Institute of Biotechnology and Pharmaceutical Research , National Health Research Institutes , Miaoli 35053 , Taiwan , ROC
| | - Kuan-Liang Liu
- Institute of Biotechnology and Pharmaceutical Research , National Health Research Institutes , Miaoli 35053 , Taiwan , ROC
| | - Chen-Fu Lo
- Institute of Biotechnology and Pharmaceutical Research , National Health Research Institutes , Miaoli 35053 , Taiwan , ROC
| | - Ming-Yu Fang
- Institute of Biotechnology and Pharmaceutical Research , National Health Research Institutes , Miaoli 35053 , Taiwan , ROC
| | - Yu-Cheng Huang
- Institute of Biotechnology and Pharmaceutical Research , National Health Research Institutes , Miaoli 35053 , Taiwan , ROC
| | - Teng-Kuang Yeh
- Institute of Biotechnology and Pharmaceutical Research , National Health Research Institutes , Miaoli 35053 , Taiwan , ROC
| | - Koon Y Pak
- Molecular Targeting Technologies, Inc. , West Chester , Pennsylvania 19380 , United States
| | - Brian D Gray
- Molecular Targeting Technologies, Inc. , West Chester , Pennsylvania 19380 , United States
| | - Tsu-An Hsu
- Institute of Biotechnology and Pharmaceutical Research , National Health Research Institutes , Miaoli 35053 , Taiwan , ROC
| | - Kuan-Hsun Huang
- Institute of Biotechnology and Pharmaceutical Research , National Health Research Institutes , Miaoli 35053 , Taiwan , ROC
| | - Chuan Shih
- Institute of Biotechnology and Pharmaceutical Research , National Health Research Institutes , Miaoli 35053 , Taiwan , ROC
| | - Kak-Shan Shia
- Institute of Biotechnology and Pharmaceutical Research , National Health Research Institutes , Miaoli 35053 , Taiwan , ROC
| | - Chiung-Tong Chen
- Institute of Biotechnology and Pharmaceutical Research , National Health Research Institutes , Miaoli 35053 , Taiwan , ROC
| | - Lun K Tsou
- Institute of Biotechnology and Pharmaceutical Research , National Health Research Institutes , Miaoli 35053 , Taiwan , ROC
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20
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Cationic gold nanoparticles elicit mitochondrial dysfunction: a multi-omics study. Sci Rep 2019; 9:4366. [PMID: 30867451 PMCID: PMC6416392 DOI: 10.1038/s41598-019-40579-6] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Accepted: 02/19/2019] [Indexed: 01/05/2023] Open
Abstract
Systems biology is increasingly being applied in nanosafety research for observing and predicting the biological perturbations inflicted by exposure to nanoparticles (NPs). In the present study, we used a combined transcriptomics and proteomics approach to assess the responses of human monocytic cells to Au-NPs of two different sizes with three different surface functional groups, i.e., alkyl ammonium bromide, alkyl sodium carboxylate, or poly(ethylene glycol) (PEG)-terminated Au-NPs. Cytotoxicity screening using THP-1 cells revealed a pronounced cytotoxicity for the ammonium-terminated Au-NPs, while no cell death was seen after exposure to the carboxylated or PEG-modified Au-NPs. Moreover, Au-NR3+ NPs, but not the Au-COOH NPs, were found to trigger dose-dependent lethality in vivo in the model organism, Caenorhabditis elegans. RNA sequencing combined with mass spectrometry-based proteomics predicted that the ammonium-modified Au-NPs elicited mitochondrial dysfunction. The latter results were validated by using an array of assays to monitor mitochondrial function. Au-NR3+ NPs were localized in mitochondria of THP-1 cells. Moreover, the cationic Au-NPs triggered autophagy in macrophage-like RFP-GFP-LC3 reporter cells, and cell death was aggravated upon inhibition of autophagy. Taken together, these studies have disclosed mitochondria-dependent effects of cationic Au-NPs resulting in the rapid demise of the cells.
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21
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Nishi C, Yanagihashi Y, Segawa K, Nagata S. MERTK tyrosine kinase receptor together with TIM4 phosphatidylserine receptor mediates distinct signal transduction pathways for efferocytosis and cell proliferation. J Biol Chem 2019; 294:7221-7230. [PMID: 30846565 DOI: 10.1074/jbc.ra118.006628] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2018] [Revised: 02/26/2019] [Indexed: 12/12/2022] Open
Abstract
Apoptotic cells expose phosphatidylserine (PtdSer) on their surface, leading to efferocytosis, i.e. their engulfment by resident macrophages that express the PtdSer receptor T cell immunoglobulin mucin receptor 4 (TIM4) and TAM family receptor tyrosine kinase receptors (MERTK, AXL, and TYRO3). TAM family receptors stimulate cell proliferation, and the many aspects of the growth signaling pathway downstream of TAM family receptors have been elucidated previously. However, the signaling cascade for TAM receptor-mediated efferocytosis has been elusive. Here we observed that efferocytosis by mouse-resident peritoneal macrophages was blocked by inhibitors against the MERTK, mitogen-activated protein kinase/extracellular signal-regulated kinase kinase (MEK), AKT Ser/Thr kinase (AKT), focal adhesion kinase (FAK), or STAT6 pathway. Accordingly, apoptotic cells stimulated the phosphorylation of MERTK, ERK, AKT, FAK, and STAT6, but not of IκB or STAT5. A reconstituted efferocytosis system using MERTK- and TIM4-expressing NIH3T3-derived cells revealed that the juxtamembrane and C-terminal regions of MERTK have redundant roles in efferocytosis. The transformation of murine IL-3-dependent Ba/F3 cells (a pro-B cell line) with MERTK and TIM4 enabled them to proliferate in response to apoptotic cells in a PtdSer-dependent manner. This apoptotic cell-induced MERTK-mediated proliferation required both MERTK's juxtamembrane and C-terminal regions and was blocked by inhibitors of not only ERK, AKT, FAK, and STAT6 but also of NF-κB and STAT5 signaling. These results suggest that apoptotic cells stimulate distinct sets of signal transduction pathways via MERTK to induce either efferocytosis or proliferation.
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Affiliation(s)
- Chihiro Nishi
- From the Laboratory of Biochemistry and Immunology, World Premier International Immunology Frontier Research Center, Osaka University, Suita, Osaka 565-0871, Japan
| | - Yuichi Yanagihashi
- From the Laboratory of Biochemistry and Immunology, World Premier International Immunology Frontier Research Center, Osaka University, Suita, Osaka 565-0871, Japan
| | - Katsumori Segawa
- From the Laboratory of Biochemistry and Immunology, World Premier International Immunology Frontier Research Center, Osaka University, Suita, Osaka 565-0871, Japan
| | - Shigekazu Nagata
- From the Laboratory of Biochemistry and Immunology, World Premier International Immunology Frontier Research Center, Osaka University, Suita, Osaka 565-0871, Japan
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22
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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] [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.
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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
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23
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Li J, Ma L, Liao X, Liu D, Lu X, Chen S, Ye X, Ding T. Ultrasound-Induced Escherichia coli O157:H7 Cell Death Exhibits Physical Disruption and Biochemical Apoptosis. Front Microbiol 2018; 9:2486. [PMID: 30459727 PMCID: PMC6232819 DOI: 10.3389/fmicb.2018.02486] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Accepted: 09/28/2018] [Indexed: 12/30/2022] Open
Abstract
Ultrasound has attracted great interest of both industry and scientific communities for its potential use as a physical processing and preservation tool. In this study, Escherichia coli O157:H7 was selected as the model microbe to investigate the ultrasound-induced cell death. Slight variations in membrane potential and ion exchanges across membrane induced by low-intensity ultrasound increased the membrane permeability of E. coli O157:H7, and this reversible sublethal effect can preserve the viability of E. coli O157:H7 and meanwhile be beneficial for bioprocessing application. In comparison, high-intensity ultrasound resulted in irreversible lethal effect on E. coli O157:H7, which can be applied in the field of microbial inactivation. In addition, both low- and high-intensity ultrasound induced either physical destruction or trigger genetically encoded apoptosis of E. coli O157:H7. Accumulation of reactive oxygen species and decrease of adenosine tri-phosphate might be related to the physiological and biochemical hallmarks of apoptosis, including exposed phosphatidylserine and activated caspases in E. coli O157:H7. The result provides novel insight into the mechanisms of non-thermal physical treatment on the inactivation of bacteria and lays foundation for the further research on the cell signaling and metabolic pathway in apoptotic bacteria.
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Affiliation(s)
- Jiao Li
- Department of Food Science and Nutrition, National Engineering Laboratory of Intelligent Food Technology and Equipment, Zhejiang University, Hangzhou, China.,Key Laboratory for Agro-Products Postharvest Handling of Ministry of Agriculture, Zhejiang Key Laboratory for Agro-Food Processing, Hangzhou, China
| | - Luyao Ma
- Food, Nutrition and Health Program, Faculty of Land and Food Systems, The University of British Columbia, Vancouver, BC, Canada
| | - Xinyu Liao
- Department of Food Science and Nutrition, National Engineering Laboratory of Intelligent Food Technology and Equipment, Zhejiang University, Hangzhou, China.,Key Laboratory for Agro-Products Postharvest Handling of Ministry of Agriculture, Zhejiang Key Laboratory for Agro-Food Processing, Hangzhou, China
| | - Donghong Liu
- Department of Food Science and Nutrition, National Engineering Laboratory of Intelligent Food Technology and Equipment, Zhejiang University, Hangzhou, China.,Key Laboratory for Agro-Products Postharvest Handling of Ministry of Agriculture, Zhejiang Key Laboratory for Agro-Food Processing, Hangzhou, China
| | - Xiaonan Lu
- Food, Nutrition and Health Program, Faculty of Land and Food Systems, The University of British Columbia, Vancouver, BC, Canada
| | - Shiguo Chen
- Department of Food Science and Nutrition, National Engineering Laboratory of Intelligent Food Technology and Equipment, Zhejiang University, Hangzhou, China.,Key Laboratory for Agro-Products Postharvest Handling of Ministry of Agriculture, Zhejiang Key Laboratory for Agro-Food Processing, Hangzhou, China
| | - Xingqian Ye
- Department of Food Science and Nutrition, National Engineering Laboratory of Intelligent Food Technology and Equipment, Zhejiang University, Hangzhou, China.,Key Laboratory for Agro-Products Postharvest Handling of Ministry of Agriculture, Zhejiang Key Laboratory for Agro-Food Processing, Hangzhou, China
| | - Tian Ding
- Department of Food Science and Nutrition, National Engineering Laboratory of Intelligent Food Technology and Equipment, Zhejiang University, Hangzhou, China.,Key Laboratory for Agro-Products Postharvest Handling of Ministry of Agriculture, Zhejiang Key Laboratory for Agro-Food Processing, Hangzhou, China
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24
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Jenzer C, Simionato E, Largeau C, Scarcelli V, Lefebvre C, Legouis R. Autophagy mediates phosphatidylserine exposure and phagosome degradation during apoptosis through specific functions of GABARAP/LGG-1 and LC3/LGG-2. Autophagy 2018; 15:228-241. [PMID: 30160610 DOI: 10.1080/15548627.2018.1512452] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Phagocytosis and macroautophagy/autophagy are 2 processes involved in lysosome-mediated clearance of extracellular and intracellular components, respectively. Recent studies have identified the recruitment of the autophagic protein LC3 during phagocytosis of apoptotic corpses in what is now called LC3-associated phagocytosis (LAP). LAP is a distinct process from autophagy but it relies on some members of the autophagy pathway to allow efficient degradation of the phagocytosed cargo. We investigated whether both LC3/LGG-2 and GABARAP/LGG-1 are involved in phagocytosis of apoptotic corpses during embryonic development of Caenorhabditis elegans. We discovered that both LGG-1 and LGG-2 are involved in the correct elimination of apoptotic corpses, but that they have different functions. lgg-1 and lgg-2 mutants present a delay in phagocytosis of apoptotic cells but genetic analyses indicate that LGG-1 and LGG-2 act upstream and downstream of the engulfment pathways, respectively. Moreover, LGG-1 and LGG-2 display different cellular localizations with enrichment in apoptotic corpses and phagocytic cells, respectively. For both LGG-1 and LGG-2, subcellular localization is vesicular and dependent on UNC-51/ULK1, BEC-1/BECN1 and the lipidation machinery, indicating that their functions during phagocytosis of apoptotic corpses mainly rely on autophagy. Finally, we show that LGG-1 is involved in the exposure of the 'eat-me signal' phosphatidylserine at the surface of the apoptotic cell to allow its recognition by the phagocytic cell, whereas LGG-2 is involved in later steps of phagocytosis to allow efficient cell corpse clearance by mediating the maturation/degradation of the phagosome.
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Affiliation(s)
- Céline Jenzer
- a Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS , Univ. Paris-Sud, Université Paris-Saclay , Gif-sur-Yvette cedex , France
| | - Elena Simionato
- a Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS , Univ. Paris-Sud, Université Paris-Saclay , Gif-sur-Yvette cedex , France
| | - Céline Largeau
- a Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS , Univ. Paris-Sud, Université Paris-Saclay , Gif-sur-Yvette cedex , France
| | - Vincent Scarcelli
- a Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS , Univ. Paris-Sud, Université Paris-Saclay , Gif-sur-Yvette cedex , France
| | - Christophe Lefebvre
- a Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS , Univ. Paris-Sud, Université Paris-Saclay , Gif-sur-Yvette cedex , France
| | - Renaud Legouis
- a Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS , Univ. Paris-Sud, Université Paris-Saclay , Gif-sur-Yvette cedex , France
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25
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Falzone ME, Malvezzi M, Lee BC, Accardi A. Known structures and unknown mechanisms of TMEM16 scramblases and channels. J Gen Physiol 2018; 150:933-947. [PMID: 29915161 PMCID: PMC6028493 DOI: 10.1085/jgp.201711957] [Citation(s) in RCA: 81] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2018] [Accepted: 05/29/2018] [Indexed: 12/25/2022] Open
Abstract
Falzone et al. interpret the mechanisms underlying the activity of TMEM16 family members from recent structural and functional work. The TMEM16 family of membrane proteins is composed of both Ca2+-gated Cl− channels and Ca2+-dependent phospholipid scramblases. The functional diversity of TMEM16s underlies their involvement in numerous signal transduction pathways that connect changes in cytosolic Ca2+ levels to cellular signaling networks. Indeed, defects in the function of several TMEM16s cause a variety of genetic disorders, highlighting their fundamental pathophysiological importance. Here, we review how our mechanistic understanding of TMEM16 function has been shaped by recent functional and structural work. Remarkably, the recent determination of near-atomic-resolution structures of TMEM16 proteins of both functional persuasions has revealed how relatively minimal rearrangements in the substrate translocation pathway are sufficient to precipitate the dramatic functional differences that characterize the family. These structures, when interpreted in the light of extensive functional analysis, point to an unusual mechanism for Ca2+-dependent activation of TMEM16 proteins in which substrate permeation is regulated by a combination of conformational rearrangements and electrostatics. These breakthroughs pave the way to elucidate the mechanistic bases of ion and lipid transport by the TMEM16 proteins and unravel the molecular links between these transport activities and their function in human pathophysiology.
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Affiliation(s)
- Maria E Falzone
- Department of Biochemistry, Weill Cornell Medical School, New York, NY
| | - Mattia Malvezzi
- Department of Anesthesiology, Weill Cornell Medical School, New York, NY
| | - Byoung-Cheol Lee
- Department of Anesthesiology, Weill Cornell Medical School, New York, NY
| | - Alessio Accardi
- Department of Biochemistry, Weill Cornell Medical School, New York, NY .,Department of Anesthesiology, Weill Cornell Medical School, New York, NY.,Department of Physiology, Biophysics and Systems Biology, Weill Cornell Medical School, New York, NY
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26
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Kumar S, Calianese D, Birge RB. Efferocytosis of dying cells differentially modulate immunological outcomes in tumor microenvironment. Immunol Rev 2018; 280:149-164. [PMID: 29027226 DOI: 10.1111/imr.12587] [Citation(s) in RCA: 58] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Programmed cell death (apoptosis) is an integral part of tissue homeostasis in complex organisms, allowing for tissue turnover, repair, and renewal while simultaneously inhibiting the release of self antigens and danger signals from apoptotic cell-derived constituents that can result in immune activation, inflammation, and autoimmunity. Unlike cells in culture, the physiological fate of cells that die by apoptosis in vivo is their rapid recognition and engulfment by phagocytic cells (a process called efferocytosis). To this end, apoptotic cells express specific eat-me signals, such as externalized phosphatidylserine (PS), that are recognized in a specific context by receptors to initiate signaling pathways for engulfment. The importance of carefully regulated recognition and clearance pathways is evident in the spectrum of inflammatory and autoimmune disorders caused by defects in PS receptors and signaling molecules. However, in recent years, several additional cell death pathways have emerged, including immunogenic cell death, necroptosis, pyroptosis, and netosis that interweave different cell death pathways with distinct innate and adaptive responses from classical apoptosis that can shape long-term host immunity. In this review, we discuss the role of different cell death pathways in terms of their immune potential outcomes specifically resulting in specific cell corpse/phagocyte interactions (phagocytic synapses) that impinge on host immunity, with a main emphasis on tolerance and cancer immunotherapy.
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Affiliation(s)
- Sushil Kumar
- New Jersey Medical School, Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers University, Newark, NJ, USA
| | - David Calianese
- New Jersey Medical School, Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers University, Newark, NJ, USA
| | - Raymond B Birge
- New Jersey Medical School, Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers University, Newark, NJ, USA
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C. elegans Blastomeres Clear the Corpse of the Second Polar Body by LC3-Associated Phagocytosis. Cell Rep 2018; 23:2070-2082. [DOI: 10.1016/j.celrep.2018.04.043] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Revised: 02/22/2018] [Accepted: 04/10/2018] [Indexed: 12/16/2022] Open
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Abstract
The human body generates 10-100 billion cells every day, and the same number of cells die to maintain homeostasis in our body. Cells infected by bacteria or viruses also die. The cell death that occurs under physiological conditions mainly proceeds by apoptosis, which is a noninflammatory, or silent, process, while pathogen infection induces necroptosis or pyroptosis, which activates the immune system and causes inflammation. Dead cells generated by apoptosis are quickly engulfed by macrophages for degradation. Caspases are a large family of cysteine proteases that act in cascades. A cascade that leads to caspase 3 activation mediates apoptosis and is responsible for killing cells, recruiting macrophages, and presenting an "eat me" signal(s). When apoptotic cells are not efficiently engulfed by macrophages, they undergo secondary necrosis and release intracellular materials that represent a damage-associated molecular pattern, which may lead to a systemic lupus-like autoimmune disease.
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Affiliation(s)
- Shigekazu Nagata
- Laboratory of Biochemistry and Immunology, World Premier International Research Center Initiative Immunology Frontier Research Center, Osaka University, Osaka 565-0871, Japan;
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29
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Phosphatidylserine save-me signals drive functional recovery of severed axons in Caenorhabditis elegans. Proc Natl Acad Sci U S A 2017; 114:E10196-E10205. [PMID: 29109263 PMCID: PMC5703272 DOI: 10.1073/pnas.1703807114] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Nervous system injury can cause lifelong disability, because repair rarely leads to reconnection with the target tissue. In the nematode Caenorhabditis elegans and in several other species, regeneration can proceed through a mechanism of axonal fusion, whereby regrowing axons reconnect and fuse with their own separated fragments, rapidly and efficiently restoring the original axonal tract. We have found that the process of axonal fusion restores full function to damaged neurons. In addition, we show that injury-induced changes to the axonal membrane that result in exposure of lipid “save-me” signals mediate the level of axonal fusion. Thus, our results establish axonal fusion as a complete regenerative mechanism that can be modulated by changing the level of save-me signals exposed after injury. Functional regeneration after axonal injury requires transected axons to regrow and reestablish connection with their original target tissue. The spontaneous regenerative mechanism known as axonal fusion provides a highly efficient means of achieving targeted reconnection, as a regrowing axon is able to recognize and fuse with its own detached axon segment, thereby rapidly reestablishing the original axonal tract. Here, we use behavioral assays and fluorescent reporters to show that axonal fusion enables full recovery of function after axotomy of Caenorhabditis elegans mechanosensory neurons. Furthermore, we reveal that the phospholipid phosphatidylserine, which becomes exposed on the damaged axon to function as a “save-me” signal, defines the level of axonal fusion. We also show that successful axonal fusion correlates with the regrowth potential and branching of the proximal fragment and with the retraction length and degeneration of the separated segment. Finally, we identify discrete axonal domains that vary in their propensity to regrow through fusion and show that the level of axonal fusion can be genetically modulated. Taken together, our results reveal that axonal fusion restores full function to injured neurons, is dependent on exposure of phospholipid signals, and is achieved through the balance between regenerative potential and level of degeneration.
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30
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Kim GW, Nam GH, Kim IS, Park SY. Xk-related protein 8 regulates myoblast differentiation and survival. FEBS J 2017; 284:3575-3588. [PMID: 28881496 DOI: 10.1111/febs.14261] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Revised: 07/26/2017] [Accepted: 09/05/2017] [Indexed: 12/14/2022]
Abstract
Xk-related protein 8 (Xkr8) is a scramblase and responsible for phosphatidylserine (PS) exposure on the cell surface in a caspase-dependent manner. Although PS exposure is found to be important for myotube formation during myoblast differentiation, the role of Xkr8 during myogenesis has not been elucidated. Here we show that Xkr8 contributes to myoblast differentiation. Xkr8 overexpression induced the formation of large myotubes during early differentiation, but this phenotype was not related to caspase-dependent cleavage of Xkr8. Furthermore, forced Xkr8 expression accelerated myoblast differentiation and conferred cell-death resistance after the induction of differentiation. Consistent with these results, Xkr8-knocked-down myoblasts exhibited impaired differentiation and more apoptotic cells during differentiation, implying the involvements of Xkr8 in the survival and proliferation of myoblasts. Taken together, the study shows Xkr8 influences myogenesis by acting as a positive regulator of terminal differentiation and myoblast survival.
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Affiliation(s)
- Go-Woon Kim
- Center for Theragnosis, Biomedical Research Institute, Korea Institute of Science and Technology (KIST), Seoul, Korea
| | - Gi-Hoon Nam
- Center for Theragnosis, Biomedical Research Institute, Korea Institute of Science and Technology (KIST), Seoul, Korea.,KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul, Korea
| | - In-San Kim
- Center for Theragnosis, Biomedical Research Institute, Korea Institute of Science and Technology (KIST), Seoul, Korea.,KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul, Korea
| | - Seung-Yoon Park
- Center for Theragnosis, Biomedical Research Institute, Korea Institute of Science and Technology (KIST), Seoul, Korea.,Department of Biochemistry, School of Medicine, Dongguk University, Gyeongju, Korea
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31
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Conradt B. Partners in Crime. Dev Cell 2017. [PMID: 28633011 DOI: 10.1016/j.devcel.2017.06.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Caspases have apoptotic and non-apoptotic functions, both of which depend on their abilities to cleave proteins at specific sites. What distinguishes apoptotic from non-apoptotic substrates has so far been unclear. In this issue of Developmental Cell, Weaver et al. (2017) now provide an answer to this crucial question.
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Affiliation(s)
- Barbara Conradt
- Center for Integrated Protein Science Munich (CIPSM), Department Biology II, Ludwig-Maximilians-University Munich, Großhaderner Straße 2, 82152 Planegg-Martinsried, Germany.
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32
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Programmed Cell Death During Caenorhabditis elegans Development. Genetics 2017; 203:1533-62. [PMID: 27516615 DOI: 10.1534/genetics.115.186247] [Citation(s) in RCA: 66] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2016] [Accepted: 04/22/2016] [Indexed: 12/21/2022] Open
Abstract
Programmed cell death is an integral component of Caenorhabditis elegans development. Genetic and reverse genetic studies in C. elegans have led to the identification of many genes and conserved cell death pathways that are important for the specification of which cells should live or die, the activation of the suicide program, and the dismantling and removal of dying cells. Molecular, cell biological, and biochemical studies have revealed the underlying mechanisms that control these three phases of programmed cell death. In particular, the interplay of transcriptional regulatory cascades and networks involving multiple transcriptional regulators is crucial in activating the expression of the key death-inducing gene egl-1 and, in some cases, the ced-3 gene in cells destined to die. A protein interaction cascade involving EGL-1, CED-9, CED-4, and CED-3 results in the activation of the key cell death protease CED-3, which is tightly controlled by multiple positive and negative regulators. The activation of the CED-3 caspase then initiates the cell disassembly process by cleaving and activating or inactivating crucial CED-3 substrates; leading to activation of multiple cell death execution events, including nuclear DNA fragmentation, mitochondrial elimination, phosphatidylserine externalization, inactivation of survival signals, and clearance of apoptotic cells. Further studies of programmed cell death in C. elegans will continue to advance our understanding of how programmed cell death is regulated, activated, and executed in general.
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33
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Engulfment signals and the phagocytic machinery for apoptotic cell clearance. Exp Mol Med 2017; 49:e331. [PMID: 28496201 PMCID: PMC5454446 DOI: 10.1038/emm.2017.52] [Citation(s) in RCA: 101] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Accepted: 12/15/2016] [Indexed: 02/07/2023] Open
Abstract
The clearance of apoptotic cells is an essential process for tissue homeostasis. To this end, cells undergoing apoptosis must display engulfment signals, such as ‘find-me' and ‘eat-me' signals. Engulfment signals are recognized by multiple types of phagocytic machinery in phagocytes, leading to prompt clearance of apoptotic cells. In addition, apoptotic cells and phagocytes release tolerogenic signals to reduce immune responses against apoptotic cell-derived self-antigens. Here we discuss recent advances in our knowledge of engulfment signals, the phagocytic machinery and the signal transduction pathways for apoptotic cell engulfment.
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34
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Li R, Liu Y, Pedersen HS, Callesen H. Cytoplasmic membrane activities during first cleavage of zona-free porcine embryos: description and consequences. Reprod Fertil Dev 2017; 29:557-564. [DOI: 10.1071/rd15179] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2015] [Accepted: 08/26/2015] [Indexed: 11/23/2022] Open
Abstract
Already at first embryo cleavage subsequent blastocyst formation can be predicted based on morphology but the finer morphological details can be difficult to determine due to the presence of the zona pellucida (ZP). Therefore, we monitored zona-free porcine parthenogenetically activated (PA) embryos in a time-lapse system to: (1) describe and characterise the morphological activity of the cytoplasmic membrane and the distribution to the two nuclei during first cleavage and (2) determine the relationship between specific morphological activities and subsequent embryonic development. After ZP removal the membrane surface activities were clearly visible, so all cleaved embryos could be divided into two groups depending on the surface activity during first cleavage: regular morphology (MN) or irregular morphology with ‘bumps’ (MB). The two nuclei were more unequal in MB embryos in both nucleus size and DNA quantity. After first cleavage, MB embryos could be further divided into three types of irregularities (MB1, MB2, MB3) based on their subsequent behaviour. Clear differences in developmental patterns were found between MN and MB embryos, such as delayed first cleavage, compromised blastocyst formation and total cell number. The predictive value of these new types of morphological events was comparable to the more traditionally used time of first cleavage. In conclusion, zona-free embryos allow visualisation of finer morphological details that can provide an early prediction of embryo developmental potential, but further studies are needed on other type of embryos.
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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] [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.
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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.
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36
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Wang X, Yang C. Programmed cell death and clearance of cell corpses in Caenorhabditis elegans. Cell Mol Life Sci 2016; 73:2221-36. [PMID: 27048817 PMCID: PMC11108496 DOI: 10.1007/s00018-016-2196-z] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Accepted: 03/18/2016] [Indexed: 01/01/2023]
Abstract
Programmed cell death is critical to the development of diverse animal species from C. elegans to humans. In C. elegans, the cell death program has three genetically distinguishable phases. During the cell suicide phase, the core cell death machinery is activated through a protein interaction cascade. This activates the caspase CED-3, which promotes numerous pro-apoptotic activities including DNA degradation and exposure of the phosphatidylserine "eat me" signal on the cell corpse surface. Specification of the cell death fate involves transcriptional activation of the cell death initiator EGL-1 or the caspase CED-3 by coordinated actions of specific transcription factors in distinct cell types. In the cell corpse clearance stage, recognition of cell corpses by phagocytes triggers several signaling pathways to induce phagocytosis of apoptotic cell corpses. Cell corpse-enclosing phagosomes ultimately fuse with lysosomes for digestion of phagosomal contents. This article summarizes our current knowledge about programmed cell death and clearance of cell corpses in C. elegans.
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Affiliation(s)
- Xiaochen Wang
- National Institute of Biological Sciences, No. 7 Science Park Road, Zhongguancun Life Science Park, Beijing, 102206, China.
| | - Chonglin Yang
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, No. 1 West Beichen Road, Chaoyang District, Beijing, 100101, China.
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37
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Sullivan KD, Nakagawa A, Xue D, Espinosa JM. Human ACAP2 is a homolog of C. elegans CNT-1 that promotes apoptosis in cancer cells. Cell Cycle 2016; 14:1771-8. [PMID: 25853217 DOI: 10.1080/15384101.2015.1026518] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Activation of caspases is an integral part of the apoptotic cell death program. Collectively, these proteases target hundreds of substrates, leading to the hypothesis that apoptosis is "death by a thousand cuts". Recent work, however, has demonstrated that caspase cleavage of only a subset of these substrates directs apoptosis in the cell. One such example is C. elegans CNT-1, which is cleaved by CED-3 to generate a truncated form, tCNT-1, that acquires a potent phosphoinositide-binding activity and translocates to the plasma membrane where it inactivates AKT survival signaling. We report here that ACAP2, a homolog of C. elegans CNT-1, has a pro-apoptotic function and an identical phosphoinositide-binding pattern to that of tCNT-1, despite not being an apparent target of caspase cleavage. We show that knockdown of ACAP2 blocks apoptosis in cancer cells in response to the chemotherapeutic antimetabolite 5-fluorouracil and that ACAP2 expression is down-regulated in some esophageal cancers, leukemias and lymphomas. These results suggest that ACAP2 is a functional homolog of C. elegans CNT-1 and its inactivation or downregulation in human cells may contribute to cancer development.
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Affiliation(s)
- Kelly D Sullivan
- a Department of Molecular, Cellular, and Developmental Biology; University of Colorado ; Boulder , CO , USA
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38
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Bevers EM, Williamson PL. Getting to the Outer Leaflet: Physiology of Phosphatidylserine Exposure at the Plasma Membrane. Physiol Rev 2016; 96:605-45. [PMID: 26936867 DOI: 10.1152/physrev.00020.2015] [Citation(s) in RCA: 287] [Impact Index Per Article: 35.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Phosphatidylserine (PS) is a major component of membrane bilayers whose change in distribution between inner and outer leaflets is an important physiological signal. Normally, members of the type IV P-type ATPases spend metabolic energy to create an asymmetric distribution of phospholipids between the two leaflets, with PS confined to the cytoplasmic membrane leaflet. On occasion, membrane enzymes, known as scramblases, are activated to facilitate transbilayer migration of lipids, including PS. Recently, two proteins required for such randomization have been identified: TMEM16F, a scramblase regulated by elevated intracellular Ca(2+), and XKR8, a caspase-sensitive protein required for PS exposure in apoptotic cells. Once exposed at the cell surface, PS regulates biochemical reactions involved in blood coagulation, and bone mineralization, and also regulates a variety of cell-cell interactions. Exposed on the surface of apoptotic cells, PS controls their recognition and engulfment by other cells. This process is exploited by parasites to invade their host, and in specialized form is used to maintain photoreceptors in the eye and modify synaptic connections in the brain. This review discusses what is known about the mechanism of PS exposure at the surface of the plasma membrane of cells, how actors in the extracellular milieu sense surface exposed PS, and how this recognition is translated to downstream consequences of PS exposure.
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Affiliation(s)
- Edouard M Bevers
- Department of Biochemistry, Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, The Netherlands; and Department of Biology, Amherst College, Amherst, Massachusetts
| | - Patrick L Williamson
- Department of Biochemistry, Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, The Netherlands; and Department of Biology, Amherst College, Amherst, Massachusetts
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39
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Nagata S, Suzuki J, Segawa K, Fujii T. Exposure of phosphatidylserine on the cell surface. Cell Death Differ 2016; 23:952-61. [PMID: 26891692 DOI: 10.1038/cdd.2016.7] [Citation(s) in RCA: 298] [Impact Index Per Article: 37.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Accepted: 01/11/2016] [Indexed: 12/15/2022] Open
Abstract
Phosphatidylserine (PtdSer) is a phospholipid that is abundant in eukaryotic plasma membranes. An ATP-dependent enzyme called flippase normally keeps PtdSer inside the cell, but PtdSer is exposed by the action of scramblase on the cell's surface in biological processes such as apoptosis and platelet activation. Once exposed to the cell surface, PtdSer acts as an 'eat me' signal on dead cells, and creates a scaffold for blood-clotting factors on activated platelets. The molecular identities of the flippase and scramblase that work at plasma membranes have long eluded researchers. Indeed, their identity as well as the mechanism of the PtdSer exposure to the cell surface has only recently been revealed. Here, we describe how PtdSer is exposed in apoptotic cells and in activated platelets, and discuss PtdSer exposure in other biological processes.
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Affiliation(s)
- S Nagata
- Laboratory of Biochemistry & Immunology, Immunology Frontier Research Center, Osaka University, Suita, Osaka 565-0871, Japan
| | - J Suzuki
- Laboratory of Biochemistry & Immunology, Immunology Frontier Research Center, Osaka University, Suita, Osaka 565-0871, Japan
| | - K Segawa
- Laboratory of Biochemistry & Immunology, Immunology Frontier Research Center, Osaka University, Suita, Osaka 565-0871, Japan
| | - T Fujii
- Laboratory of Biochemistry & Immunology, Immunology Frontier Research Center, Osaka University, Suita, Osaka 565-0871, Japan
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40
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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] [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.
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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:
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42
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Williamson P. Phospholipid Scramblases. Lipid Insights 2016; 8:41-4. [PMID: 26843813 PMCID: PMC4737519 DOI: 10.4137/lpi.s31785] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2015] [Revised: 11/29/2015] [Accepted: 12/03/2015] [Indexed: 12/22/2022] Open
Abstract
The distribution of phospholipid types between the two leaflets of a membrane bilayer is a controlled feature of membrane structure. One of the two membrane catalytic activities governing this distribution randomizes the composition of the two leaflets-the phospholipid scramblases. Two proteins (Xkr8 and TMEM16F) required for the activation of these activities have been identified. One of these proteins (TMEM16F) is quite clearly a scramblase itself and provides insight into the mechanism by which transbilayer phospholipid movement is facilitated.
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43
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Montigny C, Lyons J, Champeil P, Nissen P, Lenoir G. On the molecular mechanism of flippase- and scramblase-mediated phospholipid transport. Biochim Biophys Acta Mol Cell Biol Lipids 2015; 1861:767-783. [PMID: 26747647 DOI: 10.1016/j.bbalip.2015.12.020] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2015] [Revised: 12/20/2015] [Accepted: 12/28/2015] [Indexed: 11/20/2022]
Abstract
Phospholipid flippases are key regulators of transbilayer lipid asymmetry in eukaryotic cell membranes, critical to many trafficking and signaling pathways. P4-ATPases, in particular, are responsible for the uphill transport of phospholipids from the exoplasmic to the cytosolic leaflet of the plasma membrane, as well as membranes of the late secretory/endocytic pathways, thereby establishing transbilayer asymmetry. Recent studies combining cell biology and biochemical approaches have improved our understanding of the path taken by lipids through P4-ATPases. Additionally, identification of several protein families catalyzing phospholipid 'scrambling', i.e. disruption of phospholipid asymmetry through energy-independent bi-directional phospholipid transport, as well as the recent report of the structure of such a scramblase, opens the way to a deeper characterization of their mechanism of action. Here, we discuss the molecular nature of the mechanism by which lipids may 'flip' across membranes, with an emphasis on active lipid transport catalyzed by P4-ATPases. This article is part of a Special Issue entitled: The cellular lipid landscape edited by Tim P. Levine and Anant K. Menon.
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Affiliation(s)
- Cédric Montigny
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ Paris-Sud, Université Paris-Saclay, 91198 Gif-sur-Yvette, France
| | - Joseph Lyons
- DANDRITE, Nordic-EMBL Partnership for Molecular Medicine, and PUMPkin, Danish National Research Foundation, Aarhus University, Department of Molecular Biology and Genetics, Gustav Wieds Vej 10C, 8000 Aarhus C, Denmark
| | - Philippe Champeil
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ Paris-Sud, Université Paris-Saclay, 91198 Gif-sur-Yvette, France
| | - Poul Nissen
- DANDRITE, Nordic-EMBL Partnership for Molecular Medicine, and PUMPkin, Danish National Research Foundation, Aarhus University, Department of Molecular Biology and Genetics, Gustav Wieds Vej 10C, 8000 Aarhus C, Denmark
| | - Guillaume Lenoir
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ Paris-Sud, Université Paris-Saclay, 91198 Gif-sur-Yvette, France.
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Chakraborty S, Lambie EJ, Bindu S, Mikeladze-Dvali T, Conradt B. Engulfment pathways promote programmed cell death by enhancing the unequal segregation of apoptotic potential. Nat Commun 2015; 6:10126. [PMID: 26657541 PMCID: PMC4682117 DOI: 10.1038/ncomms10126] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2015] [Accepted: 11/04/2015] [Indexed: 12/14/2022] Open
Abstract
Components of the conserved engulfment pathways promote programmed cell death in Caenorhabditis elegans (C. elegans) through an unknown mechanism. Here we report that the phagocytic receptor CED-1 mEGF10 is required for the formation of a dorsal–ventral gradient of CED-3 caspase activity within the mother of a cell programmed to die and an increase in the level of CED-3 protein within its dying daughter. Furthermore, CED-1 becomes enriched on plasma membrane regions of neighbouring cells that appose the dorsal side of the mother, which later forms the dying daughter. Therefore, we propose that components of the engulfment pathways promote programmed cell death by enhancing the polar localization of apoptotic factors in mothers of cells programmed to die and the unequal segregation of apoptotic potential into dying and surviving daughters. Our findings reveal a novel function of the engulfment pathways and provide a better understanding of how apoptosis is initiated during C. elegans development. Programed cell death occurs in a stereotypic fashion during C. elegans development, and it is thought that engulfment promotes programmed cell death. Here the authors present evidence that a signaling function of the conserved engulfment pathways, not the process of engulfment itself, promotes apoptotic cell death.
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Affiliation(s)
- Sayantan Chakraborty
- Department of Biology II, Ludwig-Maximilians-University, Munich, Center for Integrated Protein Science Munich-CIPSM, LMU Biocenter, Planegg-Martinsried 82152, Germany
| | - Eric J Lambie
- Department of Biology II, Ludwig-Maximilians-University, Munich, Center for Integrated Protein Science Munich-CIPSM, LMU Biocenter, Planegg-Martinsried 82152, Germany
| | - Samik Bindu
- Department of Biology II, Ludwig-Maximilians-University, Munich, Center for Integrated Protein Science Munich-CIPSM, LMU Biocenter, Planegg-Martinsried 82152, Germany.,Department of Surgery Cardiac &Thoracic Surgery The University of Chicago Biological Sciences, 5841 S. Maryland Ave., Chicago, Illinosis 60637, USA
| | - Tamara Mikeladze-Dvali
- Department of Biology II, Ludwig-Maximilians-University, Munich, Center for Integrated Protein Science Munich-CIPSM, LMU Biocenter, Planegg-Martinsried 82152, Germany
| | - Barbara Conradt
- Department of Biology II, Ludwig-Maximilians-University, Munich, Center for Integrated Protein Science Munich-CIPSM, LMU Biocenter, Planegg-Martinsried 82152, Germany
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Li Z, Zhou Z. How are necrotic cells recognized by their predators? WORM 2015; 5:e1120400. [PMID: 27073733 PMCID: PMC4805362 DOI: 10.1080/21624054.2015.1120400] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Revised: 11/08/2015] [Accepted: 11/10/2015] [Indexed: 11/22/2022]
Abstract
Necrosis is a type of cell death often caused by cell injury and is linked to human diseases including neuron degeneration, stroke, and cancer. Cells undergoing necrosis are engulfed and degraded by engulfing cells, their predators. The mechanisms by which necrotic cells are recognized and removed remain elusive. Here we comment on our recent findings that reveal new molecular mechanisms of necrotic-cell recognition. Through studying the C. elegans touch neurons undergoing excitotoxic necrosis, we identified a receptor/ligand pair that enables engulfing cells to recognize necrotic neurons. The phagocytic receptor CED-1 is activated through interaction with its ligand phosphatidylserine (PS), exposed on the surface of necrotic cells. Furthermore, against the common belief that necrotic cells have ruptured plasma membrane, we found that necrotic C. elegans touch neurons actively present PS on their outer surfaces while maintaining plasma membrane integrity. We further identified 2 mechanisms governing the presentation of PS, one of which is shared with cells undergoing apoptosis, a “cell suicide” event, whereas the other is unique to necrotic neurons. The influx of Ca2+, a key necrosis-triggering factor, is implicated in activating a neuronal PS-scramblase for PS exposure. We propose that the mechanisms controlling PS-exposure and necrotic-cell recognition by engulfing cells are likely conserved from worms to humans.
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Affiliation(s)
- Zao Li
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine , Houston, TX, USA
| | - Zheng Zhou
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine , Houston, TX, USA
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Segawa K, Nagata S. An Apoptotic 'Eat Me' Signal: Phosphatidylserine Exposure. Trends Cell Biol 2015; 25:639-650. [PMID: 26437594 DOI: 10.1016/j.tcb.2015.08.003] [Citation(s) in RCA: 474] [Impact Index Per Article: 52.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2015] [Revised: 08/08/2015] [Accepted: 08/17/2015] [Indexed: 12/19/2022]
Abstract
Apoptosis and the clearance of apoptotic cells are essential processes in animal development and homeostasis. For apoptotic cells to be cleared, they must display an 'eat me' signal, most likely phosphatidylserine (PtdSer) exposure, which prompts phagocytes to engulf the cells. PtdSer, which is recognized by several different systems, is normally confined to the cytoplasmic leaflet of the plasma membrane by a 'flippase'; apoptosis activates a 'scramblase' that quickly exposes PtdSer on the cell surface. The molecules that flip and scramble phospholipids at the plasma membrane have recently been identified. Here we discuss recent findings regarding the molecular mechanisms of apoptotic PtdSer exposure and the clearance of apoptotic cells.
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Affiliation(s)
- Katsumori Segawa
- Laboratory of Biochemistry and Immunology, WPI Immunology Frontier Research Center, Osaka University, 3-1 Yamada-oka, Suita 565-0871, Japan
| | - Shigekazu Nagata
- Laboratory of Biochemistry and Immunology, WPI Immunology Frontier Research Center, Osaka University, 3-1 Yamada-oka, Suita 565-0871, Japan.
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Toda S, Nishi C, Yanagihashi Y, Segawa K, Nagata S. Clearance of Apoptotic Cells and Pyrenocytes. Curr Top Dev Biol 2015; 114:267-95. [PMID: 26431571 DOI: 10.1016/bs.ctdb.2015.07.017] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Apoptotic cells are engulfed and digested by macrophages to maintain homeostasis in animals. If dead cells are not engulfed swiftly, they undergo secondary necrosis and release intracellular components that activate the immune system. Apoptotic cells are efficiently cleared due to phosphatidylserine (PtdSer) exposed on the cell surface that acts as an "eat me" signal. PtdSer is exposed through the activation of phospholipid scramblase and the inactivation of phospholipid flippase, which are both caspase-mediated events. Macrophages express a variety of molecules to recognize PtdSer, and use a sophisticated mechanism to engulf apoptotic cells. In red blood cells, the nucleus is lost when it is extruded as a pyrenocyte during definitive erythropoiesis. These pyrenocytes (nuclei surrounded by plasma membrane) also expose PtdSer on their surface and are efficiently engulfed by macrophages in a PtdSer-dependent manner. Macrophages transfer the engulfed apoptotic cell or pyrenocyte into lysosomes, where the components of the dead cell or pyrenocyte are degraded. If lysosomes cannot digest the DNA from apoptotic cells or pyrenocytes, the undigested DNA accumulates in the lysosome and activates macrophages to produce type I interferon (IFN) via a STING-dependent pathway; in embryos, this causes severe anemia. Here, we discuss how macrophages clear apoptotic cells and pyrenocytes.
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Affiliation(s)
- Satoshi Toda
- Laboratory of Biochemistry and Immunology, Immunology Frontier Research Center, Osaka University, Osaka, Japan
| | - Chihiro Nishi
- Laboratory of Biochemistry and Immunology, Immunology Frontier Research Center, Osaka University, Osaka, Japan
| | - Yuichi Yanagihashi
- Laboratory of Biochemistry and Immunology, Immunology Frontier Research Center, Osaka University, Osaka, Japan
| | - Katsumori Segawa
- Laboratory of Biochemistry and Immunology, Immunology Frontier Research Center, Osaka University, Osaka, Japan
| | - Shigekazu Nagata
- Laboratory of Biochemistry and Immunology, Immunology Frontier Research Center, Osaka University, Osaka, Japan.
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Abstract
Apoptosis is a carefully choreographed process of cellular self-destruction in the absence of inflammation. During the death process, apoptotic cells actively communicate with their environment, signaling to both their immediate neighbors as well as distant sentinels. Some of these signals direct the anti-inflammatory immune response, instructing specific subsets of phagocytes to participate in the limited and careful clearance of dying cellular debris. These immunomodulatory signals can also regulate the activation state of the engulfing phagocytes. Other signals derived from apoptotic cells contribute to tissue growth control with the common goal of maintaining tissue integrity. Derangements in these growth control signals during prolonged apoptosis can lead to excessive cell loss or proliferation. Here, we highlight some of the most intriguing signals produced by apoptotic cells during the course of normal development as well as during physiological disturbances such as atherosclerosis and cancer.
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Abstract
Cell death is a common and important feature of animal development, and cell death defects underlie many human disease states. The nematode Caenorhabditis elegans has proven fertile ground for uncovering molecular and cellular processes controlling programmed cell death. A core pathway consisting of the conserved proteins EGL-1/BH3-only, CED-9/BCL2, CED-4/APAF1, and CED-3/caspase promotes most cell death in the nematode, and a conserved set of proteins ensures the engulfment and degradation of dying cells. Multiple regulatory pathways control cell death onset in C. elegans, and many reveal similarities with tumor formation pathways in mammals, supporting the idea that cell death plays key roles in malignant progression. Nonetheless, a number of observations suggest that our understanding of developmental cell death in C. elegans is incomplete. The interaction between dying and engulfing cells seems to be more complex than originally appreciated, and it appears that key aspects of cell death initiation are not fully understood. It has also become apparent that the conserved apoptotic pathway is dispensable for the demise of the C. elegans linker cell, leading to the discovery of a previously unexplored gene program promoting cell death. Here, we review studies that formed the foundation of cell death research in C. elegans and describe new observations that expand, and in some cases remodel, this edifice. We raise the possibility that, in some cells, more than one death program may be needed to ensure cell death fidelity.
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Affiliation(s)
| | - Shai Shaham
- Laboratory of Developmental Genetics, The Rockefeller University, New York, USA.
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So WW, Liu WN, Leung KN. Omega-3 Polyunsaturated Fatty Acids Trigger Cell Cycle Arrest and Induce Apoptosis in Human Neuroblastoma LA-N-1 Cells. Nutrients 2015; 7:6956-73. [PMID: 26295255 PMCID: PMC4555158 DOI: 10.3390/nu7085319] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2015] [Revised: 07/29/2015] [Accepted: 08/12/2015] [Indexed: 12/04/2022] Open
Abstract
Omega-3 (n-3) fatty acids are dietary long-chain fatty acids with an array of health benefits. Previous research has demonstrated the growth-inhibitory effect of n-3 fatty acids on different cancer cell lines in vitro, yet their anti-tumor effects and underlying action mechanisms on human neuroblastoma LA-N-1 cells have not yet been reported. In this study, we showed that docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) exhibited time- and concentration-dependent anti-proliferative effect on the human neuroblastoma LA-N-1 cells, but had minimal cytotoxicity on the normal or non-tumorigenic cells, as measured by MTT reduction assay. Mechanistic studies indicated that DHA and EPA triggered G0/G1 cell cycle arrest in LA-N-1 cells, as detected by flow cytometry, which was accompanied by a decrease in the expression of CDK2 and cyclin E proteins. Moreover, DHA and EPA could also induce apoptosis in LA-N-1 cells as revealed by an increase in DNA fragmentation, phosphatidylserine externalization and mitochondrial membrane depolarization. Up-regulation of Bax, activated caspase-3 and caspase-9 proteins, and down-regulation of Bcl-XL protein, might account for the occurrence of apoptotic events. Collectively, our results suggest that the growth-inhibitory effect of DHA and EPA on LA-N-1 cells might be mediated, at least in part, via triggering of cell cycle arrest and apoptosis. Therefore, DHA and EPA are potential anti-cancer agents which might be used for the adjuvant therapy or combination therapy with the conventional anti-cancer drugs for the treatment of some forms of human neuroblastoma with minimal toxicity.
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Affiliation(s)
- Wai Wing So
- Biochemistry Programme, School of Life Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong, China.
| | - Wai Nam Liu
- Biochemistry Programme, School of Life Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong, China.
| | - Kwok Nam Leung
- Biochemistry Programme, School of Life Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong, China.
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