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Saffi GT, To L, Kleine N, Melo CMP, Chen K, Genc G, Lee KCD, Chow JTS, Jang GH, Gallinger S, Botelho RJ, Salmena L. INPP4B promotes PDAC aggressiveness via PIKfyve and TRPML-1-mediated lysosomal exocytosis. J Cell Biol 2024; 223:e202401012. [PMID: 39120584 PMCID: PMC11317760 DOI: 10.1083/jcb.202401012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2024] [Revised: 05/26/2024] [Accepted: 07/29/2024] [Indexed: 08/10/2024] Open
Abstract
Aggressive solid malignancies, including pancreatic ductal adenocarcinoma (PDAC), can exploit lysosomal exocytosis to modify the tumor microenvironment, enhance motility, and promote invasiveness. However, the molecular pathways through which lysosomal functions are co-opted in malignant cells remain poorly understood. In this study, we demonstrate that inositol polyphosphate 4-phosphatase, Type II (INPP4B) overexpression in PDAC is associated with PDAC progression. We show that INPP4B overexpression promotes peripheral dispersion and exocytosis of lysosomes resulting in increased migratory and invasive potential of PDAC cells. Mechanistically, INPP4B overexpression drives the generation of PtdIns(3,5)P2 on lysosomes in a PIKfyve-dependent manner, which directs TRPML-1 to trigger the release of calcium ions (Ca2+). Our findings offer a molecular understanding of the prognostic significance of INPP4B overexpression in PDAC through the discovery of a novel oncogenic signaling axis that orchestrates migratory and invasive properties of PDAC via the regulation of lysosomal phosphoinositide homeostasis.
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Affiliation(s)
- Golam T Saffi
- Department of Pharmacology and Toxicology, University of Toronto, Toronto, Canada
| | - Lydia To
- Department of Pharmacology and Toxicology, University of Toronto, Toronto, Canada
| | - Nicholas Kleine
- Department of Pharmacology and Toxicology, University of Toronto, Toronto, Canada
| | - Ché M P Melo
- Department of Pharmacology and Toxicology, University of Toronto, Toronto, Canada
| | - Keyue Chen
- Department of Pharmacology and Toxicology, University of Toronto, Toronto, Canada
| | - Gizem Genc
- Department of Chemistry and Biology, Toronto Metropolitan University, Toronto, Canada
| | - K C Daniel Lee
- Department of Pharmacology and Toxicology, University of Toronto, Toronto, Canada
| | | | - Gun Ho Jang
- PanCuRx Translational Research Initiative, Ontario Institute for Cancer Research , Toronto, Canada
| | - Steven Gallinger
- PanCuRx Translational Research Initiative, Ontario Institute for Cancer Research , Toronto, Canada
| | - Roberto J Botelho
- Department of Chemistry and Biology, Toronto Metropolitan University, Toronto, Canada
| | - Leonardo Salmena
- Department of Pharmacology and Toxicology, University of Toronto, Toronto, Canada
- Princess Margaret Cancer Centre, University Health Network , Toronto, Canada
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2
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Giles BH, Kukolj N, Mann KK, Robaire B. Phenotypic and Functional Outcomes in Macrophages Exposed to an Environmentally Relevant Mixture of Organophosphate Esters in Vitro. ENVIRONMENTAL HEALTH PERSPECTIVES 2024; 132:87002. [PMID: 39115886 PMCID: PMC11309092 DOI: 10.1289/ehp13869] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2023] [Revised: 07/02/2024] [Accepted: 07/08/2024] [Indexed: 08/10/2024]
Abstract
BACKGROUND Organophosphate esters (OPEs) are flame retardants and plasticizers used in consumer products. OPEs are found ubiquitously throughout the environment with high concentrations in indoor house dust. Exposure to individual OPEs is associated with immune dysfunction, particularly in macrophages. However, OPEs exist as complex mixtures and the effects of environmentally relevant mixtures on the immune system have not been investigated. OBJECTIVES The objectives of this study were to evaluate the toxicity of an environmentally relevant mixture of OPEs that models Canadian house dust on macrophages using phenotypic and functional assessments in vitro. METHODS High-content live-cell fluorescent imaging for phenotypic biomarkers of toxicity in THP-1 macrophages treated with the OPE mixture was undertaken. We used confocal microscopy and cholesterol analysis to validate and expand on the observed OPE-induced lipid phenotype. Then, we used flow cytometry and live-cell imaging to conduct functional tests and uncover mechanisms of OPE-induced phagocytic suppression. Finally, we validated our THP-1 findings in human primary peripheral blood mononuclear cells (hPBMC) derived macrophages. RESULTS Exposure to non-cytotoxic dilutions of the OPE mixture resulted in higher oxidative stress and disrupted lysosome and lipid homeostasis in THP-1 and primary macrophages. We further observed that phagocytosis of apoptotic cells in THP-1 and primary macrophages was lower in OPE-exposed cells vs. controls. In THP-1 macrophages, phagocytosis of both Gram-positive and Gram-negative bacteria was also lower in OPE-exposed cells vs. controls. Additionally, the OPE mixture altered the expression of phagocytic receptors linked to the recognition of phosphatidylserine and pathogen-associated molecular patterns. DISCUSSION The results of this in vitro study suggested that exposure to an environmentally relevant mixture of OPEs resulted in higher lipid retention in macrophages and poor efferocytic response. These effects could translate to enhanced foam cell generation resulting in higher cardiovascular mortality. Furthermore, bacterial phagocytosis was lower in OPE-exposed macrophages in an in vitro setting, which may indicate the potential for reduced bacterial clearance in models of infections. Taken together, our data provide strong evidence that mixtures of OPEs can influence the biology of macrophages and offer new mechanistic insights into the impact of OPE mixtures on the immune system. https://doi.org/10.1289/EHP13869.
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Affiliation(s)
- Braeden H. Giles
- Department of Pharmacology & Therapeutics, McGill University, Montreal, Quebec, Canada
- Lady Davis Institute for Medical Research, McGill University, Montreal, Quebec, Canada
| | - Nikola Kukolj
- Department of Pharmacology & Therapeutics, McGill University, Montreal, Quebec, Canada
- Lady Davis Institute for Medical Research, McGill University, Montreal, Quebec, Canada
| | - Koren K. Mann
- Department of Pharmacology & Therapeutics, McGill University, Montreal, Quebec, Canada
- Lady Davis Institute for Medical Research, McGill University, Montreal, Quebec, Canada
| | - Bernard Robaire
- Department of Pharmacology & Therapeutics, McGill University, Montreal, Quebec, Canada
- Department of Obstetrics and Gynecology, McGill University, Montreal, Quebec, Canada
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3
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Da Graça J, Delevoye C, Morel E. Morphodynamical adaptation of the endolysosomal system to stress. FEBS J 2024. [PMID: 38706230 DOI: 10.1111/febs.17154] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2023] [Revised: 03/28/2024] [Accepted: 04/25/2024] [Indexed: 05/07/2024]
Abstract
In eukaryotes, the spatiotemporal control of endolysosomal organelles is central to the maintenance of homeostasis. By providing an interface between the cytoplasm and external environment, the endolysosomal system is placed at the forefront of the response to a wide range of stresses faced by cells. Endosomes are equipped with a dedicated set of membrane-associated proteins that ensure endosomal functions as well as crosstalk with the secretory or the autophagy pathways. Morphodynamical processes operate through local spatialization of subdomains, enabling specific remodeling and membrane contact capabilities. Consequently, the plasticity of endolysosomal organelles can be considered a robust and flexible tool exploited by cells to cope with homeostatic deviations. In this review, we provide insights into how the cellular responses to various stresses (osmotic, UV, nutrient deprivation, or pathogen infections) rely on the adaptation of the endolysosomal system morphodynamics.
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Affiliation(s)
- Juliane Da Graça
- Université Paris Cité, INSERM UMR-S1151, CNRS UMR-S8253, Institut Necker Enfants Malades, France
| | - Cédric Delevoye
- Université Paris Cité, INSERM UMR-S1151, CNRS UMR-S8253, Institut Necker Enfants Malades, France
- Institut Curie, PSL Research University, CNRS, UMR144, Structure and Membrane Compartments, Paris, France
| | - Etienne Morel
- Université Paris Cité, INSERM UMR-S1151, CNRS UMR-S8253, Institut Necker Enfants Malades, France
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4
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Tang J, Lam GT, Brooks RD, Miles M, Useckaite Z, Johnson IR, Ung BSY, Martini C, Karageorgos L, Hickey SM, Selemidis S, Hopkins AM, Rowland A, Vather R, O'Leary JJ, Brooks DA, Caruso MC, Logan JM. Exploring the role of sporadic BRAF and KRAS mutations during colorectal cancer pathogenesis: A spotlight on the contribution of the endosome-lysosome system. Cancer Lett 2024; 585:216639. [PMID: 38290660 DOI: 10.1016/j.canlet.2024.216639] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Revised: 12/21/2023] [Accepted: 12/30/2023] [Indexed: 02/01/2024]
Abstract
The highly heterogenous nature of colorectal cancer can significantly hinder its early and accurate diagnosis, eventually contributing to high mortality rates. The adenoma-carcinoma sequence and serrated polyp-carcinoma sequence are the two most common sequences in sporadic colorectal cancer. Genetic alterations in adenomatous polyposis coli (APC), v-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog (KRAS) and tumour protein 53 (TP53) genes are critical in adenoma-carcinoma sequence, whereas v-Raf murine sarcoma viral oncogene homolog B (BRAF) and MutL Homolog1 (MLH1) are driving oncogenes in the serrated polyp-carcinoma sequence. Sporadic mutations in these genes contribute differently to colorectal cancer pathogenesis by introducing distinct alterations in several signalling pathways that rely on the endosome-lysosome system. Unsurprisingly, the endosome-lysosome system plays a pivotal role in the hallmarks of cancer and contributes to specialised colon function. Thus, the endosome-lysosome system might be distinctively influenced by different mutations and these alterations may contribute to the heterogenous nature of sporadic colorectal cancer. This review highlights potential connections between major sporadic colorectal cancer mutations and the diverse pathogenic mechanisms driven by the endosome-lysosome system in colorectal carcinogenesis.
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Affiliation(s)
- Jingying Tang
- Clinical and Health Sciences, University of South Australia, North Terrace, Adelaide, South Australia, Australia
| | - Giang T Lam
- Clinical and Health Sciences, University of South Australia, North Terrace, Adelaide, South Australia, Australia
| | - Robert D Brooks
- Clinical and Health Sciences, University of South Australia, North Terrace, Adelaide, South Australia, Australia
| | - Mark Miles
- School of Health and Biomedical Sciences, STEM College, RMIT University, Bundoora, Melbourne, Vic, Australia
| | - Zivile Useckaite
- College of Medicine and Public Health, Flinders University, Flinders Drive, Bedford Park, Adelaide, SA, Australia
| | - Ian Rd Johnson
- Clinical and Health Sciences, University of South Australia, North Terrace, Adelaide, South Australia, Australia
| | - Ben S-Y Ung
- Clinical and Health Sciences, University of South Australia, North Terrace, Adelaide, South Australia, Australia
| | - Carmela Martini
- Clinical and Health Sciences, University of South Australia, North Terrace, Adelaide, South Australia, Australia
| | - Litsa Karageorgos
- Clinical and Health Sciences, University of South Australia, North Terrace, Adelaide, South Australia, Australia
| | - Shane M Hickey
- Clinical and Health Sciences, University of South Australia, North Terrace, Adelaide, South Australia, Australia
| | - Stavros Selemidis
- School of Health and Biomedical Sciences, STEM College, RMIT University, Bundoora, Melbourne, Vic, Australia
| | - Ashley M Hopkins
- College of Medicine and Public Health, Flinders University, Flinders Drive, Bedford Park, Adelaide, SA, Australia
| | - Andrew Rowland
- College of Medicine and Public Health, Flinders University, Flinders Drive, Bedford Park, Adelaide, SA, Australia
| | - Ryash Vather
- Colorectal Unit, Department of Surgery, Royal Adelaide Hospital, Adelaide, South Australia, Australia; Centre for Cancer Biology, University of South Australia, Adelaide, South Australia, Australia
| | - John J O'Leary
- Department of Histopathology, Trinity College Dublin, Dublin, Ireland
| | - Douglas A Brooks
- Clinical and Health Sciences, University of South Australia, North Terrace, Adelaide, South Australia, Australia
| | - Maria C Caruso
- Clinical and Health Sciences, University of South Australia, North Terrace, Adelaide, South Australia, Australia
| | - Jessica M Logan
- Clinical and Health Sciences, University of South Australia, North Terrace, Adelaide, South Australia, Australia.
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5
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He X, Li X, Tian W, Li C, Li P, Zhao J, Yang S, Li S. The role of redox-mediated lysosomal dysfunction and therapeutic strategies. Biomed Pharmacother 2023; 165:115121. [PMID: 37418979 DOI: 10.1016/j.biopha.2023.115121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2023] [Revised: 06/30/2023] [Accepted: 07/01/2023] [Indexed: 07/09/2023] Open
Abstract
Redox homeostasis refers to the dynamic equilibrium between oxidant and reducing agent in the body which plays a crucial role in maintaining normal physiological activities of the body. The imbalance of redox homeostasis can lead to the development of various human diseases. Lysosomes regulate the degradation of cellular proteins and play an important role in influencing cell function and fate, and lysosomal dysfunction is closely associated with the development of various diseases. In addition, several studies have shown that redox homeostasis plays a direct or indirect role in regulating lysosomes. Therefore, this paper systematically reviews the role and mechanisms of redox homeostasis in the regulation of lysosomal function. Therapeutic strategies based on the regulation of redox exerted to disrupt or restore lysosomal function are further discussed. Uncovering the role of redox in the regulation of lysosomes helps to point new directions for the treatment of many human diseases.
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Affiliation(s)
- Xiaomeng He
- Department of Pharmacy, The First Affiliated Hospital of Dalian Medical University, Dalian, China
| | - Xuening Li
- Institute of Clinical Pharmacology, Central South University, Changsha, China
| | - Wei Tian
- The First Affiliated Hospital of Dalian Medical University, Dalian, China
| | - Chenyu Li
- The First Affiliated Hospital of Dalian Medical University, Dalian, China
| | - Pengfei Li
- The First Affiliated Hospital of Dalian Medical University, Dalian, China
| | - Jingyuan Zhao
- The First Affiliated Hospital of Dalian Medical University, Dalian, China.
| | - Shilei Yang
- Department of Pharmacy, The First Affiliated Hospital of Dalian Medical University, Dalian, China.
| | - Shuai Li
- Department of Pharmacy, The First Affiliated Hospital of Dalian Medical University, Dalian, China.
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Soha SA, Santhireswaran A, Huq S, Casimir-Powell J, Jenkins N, Hodgson GK, Sugiyama M, Antonescu CN, Impellizzeri S, Botelho RJ. Improved imaging and preservation of lysosome dynamics using silver nanoparticle-enhanced fluorescence. Mol Biol Cell 2023; 34:ar96. [PMID: 37405751 PMCID: PMC10551705 DOI: 10.1091/mbc.e22-06-0200] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Revised: 06/26/2023] [Accepted: 06/27/2023] [Indexed: 07/06/2023] Open
Abstract
The dynamics of living cells can be studied by live-cell fluorescence microscopy. However, this requires the use of excessive light energy to obtain good signal-to-noise ratio, which can then photobleach fluorochromes, and more worrisomely, lead to phototoxicity. Upon light excitation, noble metal nanoparticles such as silver nanoparticles (AgNPs) generate plasmons, which can then amplify excitation in direct proximity of the nanoparticle's surface and couple to the oscillating dipole of nearby radiating fluorophores, modifying their rate of emission and thus, enhancing their fluorescence. Here, we show that AgNPs fed to cells to accumulate within lysosomes enhanced the fluorescence of lysosome-targeted Alexa488-conjugated dextran, BODIPY-cholesterol, and DQ-BSA. Moreover, AgNP increased the fluorescence of GFP fused to the cytosolic tail of LAMP1, showing that metal enhanced fluorescence can occur across the lysosomal membrane. The inclusion of AgNPs in lysosomes did not disturb lysosomal properties such as lysosomal pH, degradative capacity, autophagy and autophagic flux, and membrane integrity, though AgNP seemed to increase basal lysosome tubulation. Importantly, by using AgNP, we could track lysosome motility with reduced laser power without damaging and altering lysosome dynamics. Overall, AgNP-enhanced fluorescence may be a useful tool to study the dynamics of the endo-lysosomal pathway while minimizing phototoxicity.
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Affiliation(s)
- Sumaiya A. Soha
- Molecular Science Graduate Program, Toronto Metropolitan University, Toronto, Ontario, Canada, M5B 2K3
- Department of Chemistry and Biology, Toronto Metropolitan University, Toronto, Ontario, Canada, M5B 2K3
| | - Araniy Santhireswaran
- Department of Chemistry and Biology, Toronto Metropolitan University, Toronto, Ontario, Canada, M5B 2K3
| | - Saaimatul Huq
- Department of Chemistry and Biology, Toronto Metropolitan University, Toronto, Ontario, Canada, M5B 2K3
| | - Jayde Casimir-Powell
- Molecular Science Graduate Program, Toronto Metropolitan University, Toronto, Ontario, Canada, M5B 2K3
- Department of Chemistry and Biology, Toronto Metropolitan University, Toronto, Ontario, Canada, M5B 2K3
| | - Nicala Jenkins
- Molecular Science Graduate Program, Toronto Metropolitan University, Toronto, Ontario, Canada, M5B 2K3
- Department of Chemistry and Biology, Toronto Metropolitan University, Toronto, Ontario, Canada, M5B 2K3
| | - Gregory K. Hodgson
- Department of Chemistry and Biology, Toronto Metropolitan University, Toronto, Ontario, Canada, M5B 2K3
| | - Michael Sugiyama
- Department of Chemistry and Biology, Toronto Metropolitan University, Toronto, Ontario, Canada, M5B 2K3
| | - Costin N. Antonescu
- Molecular Science Graduate Program, Toronto Metropolitan University, Toronto, Ontario, Canada, M5B 2K3
- Department of Chemistry and Biology, Toronto Metropolitan University, Toronto, Ontario, Canada, M5B 2K3
| | - Stefania Impellizzeri
- Molecular Science Graduate Program, Toronto Metropolitan University, Toronto, Ontario, Canada, M5B 2K3
- Department of Chemistry and Biology, Toronto Metropolitan University, Toronto, Ontario, Canada, M5B 2K3
| | - Roberto J. Botelho
- Molecular Science Graduate Program, Toronto Metropolitan University, Toronto, Ontario, Canada, M5B 2K3
- Department of Chemistry and Biology, Toronto Metropolitan University, Toronto, Ontario, Canada, M5B 2K3
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7
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Lan Y, Zhang K, Wang F, Zhang Y, Yan M, Zuo Y. Polysiloxane-based hyperbranched fluorescent probe for dynamic visualization of HClO in lysosomes and vivo. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2023; 294:122527. [PMID: 36848860 DOI: 10.1016/j.saa.2023.122527] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2022] [Revised: 02/17/2023] [Accepted: 02/18/2023] [Indexed: 06/18/2023]
Abstract
As a type of reactive oxygen species, hypochlorous acid (HClO) is associated with inducing oxidative stress in lysosomes. Once its concentration is abnormal, it may lead to lysosomal rupture and subsequent apoptosis. Meanwhile, this may provide new inspiration for cancer treatment. Therefore, it is crucial to visualize HClO in lysosomes at the biological level. So far, numerous fluorescent probes have emerged to identify HClO. However, fluorescent probes that combine low biotoxicity with lysosome-targetable properties are scarce. In this paper, hyperbranched polysiloxanes were modified by embedding perylenetetracarboxylic anhydride red fluorescent cores with naphthalimide derivative green fluorophores to synthesize novel fluorescent probe (PMEA-1). PMEA-1 was a lysosome-targetable fluorescent probe with unique dual emission, high biosafety, and good response speed. PMEA-1 exhibited excellent sensitivity and responsiveness to HClO in PBS solution and could dynamically visualize HClO fluctuations in cells and zebrafish. Simultaneously, PMEA-1 also had monitoring ability for HClO produced in the process of cellular ferroptosis. In addition, the bioimaging results indicated that PMEA-1 was capable of accumulating within the lysosomes. We anticipate that PMEA-1 will broaden the application of silicon-based fluorescent probes in the field of fluorescence imaging.
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Affiliation(s)
- Ying Lan
- School of Chemistry and Chemical Engineering, School of Materials Science and Engineering, University of Jinan, Shandong 250022, PR China
| | - Kun Zhang
- School of Chemistry and Chemical Engineering, School of Materials Science and Engineering, University of Jinan, Shandong 250022, PR China
| | - Fanfan Wang
- School of Chemistry and Chemical Engineering, School of Materials Science and Engineering, University of Jinan, Shandong 250022, PR China
| | - Yafang Zhang
- School of Chemistry and Chemical Engineering, School of Materials Science and Engineering, University of Jinan, Shandong 250022, PR China
| | - Mei Yan
- School of Chemistry and Chemical Engineering, School of Materials Science and Engineering, University of Jinan, Shandong 250022, PR China.
| | - Yujing Zuo
- School of Chemistry and Chemical Engineering, School of Materials Science and Engineering, University of Jinan, Shandong 250022, PR China.
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8
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Ryan AK, Rich W, Reilly MA. Oxidative stress in the brain and retina after traumatic injury. Front Neurosci 2023; 17:1021152. [PMID: 36816125 PMCID: PMC9935939 DOI: 10.3389/fnins.2023.1021152] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2022] [Accepted: 01/13/2023] [Indexed: 02/05/2023] Open
Abstract
The brain and the retina share many physiological similarities, which allows the retina to serve as a model of CNS disease and disorder. In instances of trauma, the eye can even indicate damage to the brain via abnormalities observed such as irregularities in pupillary reflexes in suspected traumatic brain injury (TBI) patients. Elevation of reactive oxygen species (ROS) has been observed in neurodegenerative disorders and in both traumatic optic neuropathy (TON) and in TBI. In a healthy system, ROS play a pivotal role in cellular communication, but in neurodegenerative diseases and post-trauma instances, ROS elevation can exacerbate neurodegeneration in both the brain and the retina. Increased ROS can overwhelm the inherent antioxidant systems which are regulated via mitochondrial processes. The overabundance of ROS can lead to protein, DNA, and other forms of cellular damage which ultimately result in apoptosis. Even though elevated ROS have been observed to be a major cause in the neurodegeneration observed after TON and TBI, many antioxidants therapeutic strategies fail. In order to understand why these therapeutic approaches fail further research into the direct injury cascades must be conducted. Additional therapeutic approaches such as therapeutics capable of anti-inflammatory properties and suppression of other neurodegenerative processes may be needed for the treatment of TON, TBI, and neurodegenerative diseases.
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Affiliation(s)
- Annie K. Ryan
- Department of Biomedical Engineering, The Ohio State University, Columbus, OH, United States
| | - Wade Rich
- Department of Biomedical Engineering, The Ohio State University, Columbus, OH, United States
| | - Matthew A. Reilly
- Department of Biomedical Engineering, The Ohio State University, Columbus, OH, United States,Department of Ophthalmology and Visual Sciences, The Ohio State University, Columbus, OH, United States,*Correspondence: Matthew A. Reilly,
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9
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Inhibition of lipid kinase PIKfyve reveals a role for phosphatase Inpp4b in the regulation of PI(3)P-mediated lysosome dynamics through VPS34 activity. J Biol Chem 2022; 298:102187. [PMID: 35760104 PMCID: PMC9304791 DOI: 10.1016/j.jbc.2022.102187] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2022] [Revised: 06/13/2022] [Accepted: 06/15/2022] [Indexed: 11/21/2022] Open
Abstract
Lysosome membranes contain diverse phosphoinositide (PtdIns) lipids that coordinate lysosome function and dynamics. The PtdIns repertoire on lysosomes is tightly regulated by the actions of diverse PtdIns kinases and phosphatases; however, specific roles for PtdIns in lysosomal functions and dynamics are currently unclear and require further investigation. It was previously shown that PIKfyve, a lipid kinase that synthesizes PtdIns(3,5)P2 from PtdIns(3)P, controls lysosome "fusion-fission" cycle dynamics, autophagosome turnover, and endocytic cargo delivery. Furthermore, INPP4B, a PtdIns 4-phosphatase that hydrolyzes PtdIns(3,4)P2 to form PtdIns(3)P, is emerging as a cancer-associated protein with roles in lysosomal biogenesis and other lysosomal functions. Here, we investigated the consequences of disrupting PIKfyve function in Inpp4b-deficient mouse embryonic fibroblasts. Through confocal fluorescence imaging, we observed the formation of massively enlarged lysosomes, accompanied by exacerbated reduction of endocytic trafficking, disrupted lysosome fusion-fission dynamics, and inhibition of autophagy. Finally, HPLC scintillation quantification of 3H-myo-inositol labelled phosphoinositides and phosphoinositide immunofluorescence staining, we observed that lysosomal PtdIns(3)P levels were significantly elevated in Inpp4b-deficient cells due to the hyperactivation of phosphatidylinositol 3-kinase catalytic subunit VPS34 enzymatic activity. In conclusion, our study identifies a novel signaling axis that maintains normal lysosomal homeostasis and dynamics, which includes the catalytic functions of Inpp4b, PIKfyve, and VPS34.
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