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Event: 898

Key Event Title

The KE title should describe a discrete biological change that can be measured. It should generally define the biological object or process being measured and whether it is increased, decreased, or otherwise definably altered relative to a control state. For example “enzyme activity, decreased”, “hormone concentration, increased”, or “growth rate, decreased”, where the specific enzyme or hormone being measured is defined. More help

Disruption, Lysosome

Short name
The KE short name should be a reasonable abbreviation of the KE title and is used in labelling this object throughout the AOP-Wiki. The short name should be less than 80 characters in length. More help
Disruption, Lysosome

Biological Context

Structured terms, selected from a drop-down menu, are used to identify the level of biological organization for each KE. Note, KEs should be defined within a particular level of biological organization. Only KERs should be used to transition from one level of organization to another. Selection of the level of biological organization defines which structured terms will be available to select when defining the Event Components (below). More help

Cell term

Further information on Event Components and Biological Context may be viewed on the attached pdf.The biological context describes the location/biological environment in which the event takes place.  For molecular/cellular events this would include the cellular context (if known), organ context, and species/life stage/sex for which the event is relevant. For tissue/organ events cellular context is not applicable.  For individual/population events, the organ context is not applicable. More help

Organ term

Further information on Event Components and Biological Context may be viewed on the attached pdf.The biological context describes the location/biological environment in which the event takes place.  For molecular/cellular events this would include the cellular context (if known), organ context, and species/life stage/sex for which the event is relevant. For tissue/organ events cellular context is not applicable.  For individual/population events, the organ context is not applicable. More help

Key Event Components

Further information on Event Components and Biological Context may be viewed on the attached pdf.Because one of the aims of the AOP-KB is to facilitate de facto construction of AOP networks through the use of shared KE and KER elements, authors are also asked to define their KEs using a set of structured ontology terms (Event Components). In the absence of structured terms, the same KE can readily be defined using a number of synonymous titles (read by a computer as character strings). In order to make these synonymous KEs more machine-readable, KEs should also be defined by one or more “event components” consisting of a biological process, object, and action with each term originating from one of 22 biological ontologies (Ives, et al., 2017; See List). Biological process describes dynamics of the underlying biological system (e.g., receptor signalling). The biological object is the subject of the perturbation (e.g., a specific biological receptor that is activated or inhibited). Action represents the direction of perturbation of this system (generally increased or decreased; e.g., ‘decreased’ in the case of a receptor that is inhibited to indicate a decrease in the signalling by that receptor).Note that when editing Event Components, clicking an existing Event Component from the Suggestions menu will autopopulate these fields, along with their source ID and description. To clear any fields before submitting the event component, use the 'Clear process,' 'Clear object,' or 'Clear action' buttons. If a desired term does not exist, a new term request may be made via Term Requests. Event components may not be edited; to edit an event component, remove the existing event component and create a new one using the terms that you wish to add. More help
Process Object Action
organelle disassembly lysosome occurrence

Key Event Overview

AOPs Including This Key Event

All of the AOPs that are linked to this KE will automatically be listed in this subsection. This table can be particularly useful for derivation of AOP networks including the KE. Clicking on the name of the AOP will bring you to the individual page for that AOP. More help
AOP Name Role of event in AOP Point of Contact Author Status OECD Status
Receptor mediated endocytosis and lysosomal overload leading to kidney toxicity KeyEvent Allie Always (send email) Under development: Not open for comment. Do not cite Under Development
lysosomal uptake induced liver fibrosis KeyEvent Allie Always (send email) Under development: Not open for comment. Do not cite EAGMST Under Review


This is a structured field used to identify specific agents (generally chemicals) that can trigger the KE. Stressors identified in this field will be linked to the KE in a machine-readable manner, such that, for example, a stressor search would identify this as an event the stressor can trigger. NOTE: intermediate or downstream KEs in one AOP may function as MIEs in other AOPs, meaning that stressor information may be added to the KE description, even if it is a downstream KE in the pathway currently under development.Information concerning the stressors that may trigger an MIE can be defined using a combination of structured and unstructured (free-text) fields. For example, structured fields may be used to indicate specific chemicals for which there is evidence of an interaction relevant to this MIE. By linking the KE description to a structured chemical name, it will be increasingly possible to link the MIE to other sources of chemical data and information, enhancing searchability and inter-operability among different data-sources and knowledgebases. The free-text section “Evidence for perturbation of this MIE by stressor” can be used both to identify the supporting evidence for specific stressors triggering the MIE as well as to define broad chemical categories or other properties that classify the stressors able to trigger the MIE for which specific structured terms may not exist. More help

Taxonomic Applicability

Latin or common names of a species or broader taxonomic grouping (e.g., class, order, family) can be selected from an ontology. In many cases, individual species identified in these structured fields will be those for which the strongest evidence used in constructing the AOP was available in relation to this KE. More help
Term Scientific Term Evidence Link
human Homo sapiens High NCBI
mouse Mus musculus High NCBI

Life Stages

The structured ontology terms for life-stage are more comprehensive than those for taxa, but may still require further description/development and explanation in the free text section. More help
Life stage Evidence
All life stages

Sex Applicability

The authors must select from one of the following: Male, female, mixed, asexual, third gender, hermaphrodite, or unspecific. More help
Term Evidence

Key Event Description

A description of the biological state being observed or measured, the biological compartment in which it is measured, and its general role in the biology should be provided. For example, the biological state being measured could be the activity of an enzyme, the expression of a gene or abundance of an mRNA transcript, the concentration of a hormone or protein, neuronal activity, heart rate, etc. The biological compartment may be a particular cell type, tissue, organ, fluid (e.g., plasma, cerebrospinal fluid), etc. The role in the biology could describe the reaction that an enzyme catalyses and the role of that reaction within a given metabolic pathway; the protein that a gene or mRNA transcript codes for and the function of that protein; the function of a hormone in a given target tissue, physiological function of an organ, etc. Careful attention should be taken to avoid reference to other KEs, KERs or AOPs. Only describe this KE as a single isolated measurable event/state. This will ensure that the KE is modular and can be used by other AOPs, thereby facilitating construction of AOP networks. More help

Lysosomes were first described in 1955 (de Duve et al., 1955). They are acidic, single-membrane bound organelles that are present in all eukaryotic cells and are filled with more than 50 acid hydrolases to serve their purpose of degrading macromolecules (Johansson et al., 2010).

Lysosomes are the terminal organelle of the endocytic pathway, but are also involved in membrane repair and other cellular processes, such as immune responses (Repnik and Turk, 2010). There are numerous substances that can provoke increased permeability of lysosomal membrane or total lysosomal rupture, and as a consequence release of lysosomal enzymes. Among lysosomal enzymes, one of the major roles has cathepins. There are 11 cysteine cathepins in humans, B, C, F, H, K, L, O, S, V, W and X. Activation of proenzymes usually occurs within the lysosomes (Ishidoh and Kominami, 2002), therefore, the enzymes escaping from the lysosomes are in their active form. The amount of lysosomal enzymes that are released into the cytosol regulates the cell death pathway which is initiated by lysosomal damage: controlled increased permeability of lysosomal membrane, caused by limited level of stress, plays a vital role in the induction of apoptosis, whereas massive lysosomal rupture, caused by high stress levels, leads to necrosis (Bursch, 2001; Guicciardi et al., 2004). Lysosomes are known to be involved in external as well as internal apoptotic pathways. The external pathway triggers lysosomal destabilization by hydroxyl radicals, p53, and caspase 8, through activation of Bax or by ceramide which is converted into sphingosine (Terman et al., 2004). The internal apoptotic pathway on the contrary is activated through mitochondrial damage, for example via activation of Bax or Bid, phospholipases, or lysosomal enzymes (Terman et al., 2004). It has been shown that lack of cathepsin B prevents increased lysosomal membrane permeability in hepatocytes treated with TNF or sphingosine (Werneburg et al., 2002). This indicates that cathepsins can also have a role in initiation of increased lysosomal membrane permeabilization.

The lysosome contains redox-active labile irons which are suggested to be involved in local ROS production via a Fenton-type reaction (Kubota et al., 2010). It has been shown that lysosomal membrane disruption induced by lysosomotropic detergents causes early induction of lysosomal cathepsin B and D and induction of ferritin, together with an increase of cellular ROS and concomitant reduction of the antioxidants MnSOD (manganese superoxide dismutase) and GSH (glutathione), possibly due to the release of free iron into the cytosol (Ghosh et al., 2011; Hamacher-Brady et al., 2011).

The list of agents able to destabilize lysosomal membrane includes L-Leucyl-L-leucinemethyl ester (LLOMe) (Goldman and Kaplan, 1973; Uchimoto et al. 1999; Droga-Mazovec et al., 2008),  N-dodecylimidazole (NDI) (Wilson et al., 1987), sphingosine (Kagedal et al., 2001), detergent MSDH (Li et al., 2000), siramesine (Ostenfeld et al., 2005), the quinolone antibiotics ciprofloxacin and norfloxacin (Boya et al., 2003a),  hydroxychloroquine (Boya et al., 2003b) and NPs (Wang et al., 2018).

Cirman et al. showed that the lysosomotropic agent LLOMe inducing the disruption of lysosomes results in translocation of lysosomal proteases to the cytosol and induce apoptosis through a caspase dependent mechanism (Cirman et al., 2004). However, it has been proven that partially increased permeabilization of lysosome leads to apoptosis, while complete breakdown of the lysosome with release of high concentrations of the enzymes into the cytosol results in necrosis (Bursch, 2001; Kurz et al., 2008).

The short-term exposure to low concentrations of H2O2 induce lysosomal rupture by activation of phospholipase A2, which cause a progressive destabilization of the membranes of intracellular organelles degrading the membrane phospholipids (Zhao et al., 2001). Sumoza-Toledo and Penner showed that ROS activate lysosomal Ca2+ channels and contribute to increased lysosomal permeability (Sumoza-Toledo and Penner, 2011).  

Considering nanomaterials (NMs) as a trigger for lysosomal damage, recent studies underpinned the importance of lysosomal NM uptake for NM-induced toxicity. Once the material is taken up by a cell and transported to the lysosome by autophagy, the acidic milieu herein can either enhance solubility of a NM, or the material remains in its initial nano form. Both situations can induce toxicity, causing lysosomal swelling, followed by lysosomal disruption and the release of pro-apoptotic proteins (Wang et al., 2013; Cho et al., 2011; Cho et al., 2012). Wang et al. showed that the exposure of cells to NH2-PS NPs results in increased lysosomal membrane permeability and release of lysosomal proteasis (cathepsin B and cathepsin D) into cytosol (Wang et al., 2018).  

How It Is Measured or Detected

One of the primary considerations in evaluating AOPs is the relevance and reliability of the methods with which the KEs can be measured. The aim of this section of the KE description is not to provide detailed protocols, but rather to capture, in a sentence or two, per method, the type(s) of measurements that can be employed to evaluate the KE and the relative level of scientific confidence in those measurements. Methods that can be used to detect or measure the biological state represented in the KE should be briefly described and/or cited. These can range from citation of specific validated test guidelines, citation of specific methods published in the peer reviewed literature, or outlines of a general protocol or approach (e.g., a protein may be measured by ELISA).Key considerations regarding scientific confidence in the measurement approach include whether the assay is fit for purpose, whether it provides a direct or indirect measure of the biological state in question, whether it is repeatable and reproducible, and the extent to which it is accepted in the scientific and/or regulatory community. Information can be obtained from the OECD Test Guidelines website and the EURL ECVAM Database Service on Alternative Methods to Animal Experimentation (DB-ALM). ?

Lysosomes are typically analysed microscopically, usually with fluorescence microscopy (Kagedal et al., 2001).  

Changes in morphology can be observed by using acridine orange (AO), a weak base that accumulates in the acidic compartment of the cell mainly composed of lysosomes. Red fluorescence is exhibited when it is highly concentrated in acidic vesicles, while green fluorescence is exhibited when it's less concentrated in other parts of the cell (Li et al., 2000; Reiners et al., 2002; Kroemer and Jäättelä, 2005). This is followed by flow cytometry (Zhao et al., 2001), static cytofluometry or flow cytofluometry (Antunes et al., 2001).

Lysotracker green (200 nM) is regularly used to assess lysosomal acidification; Anguissola and colleagues reported that it was excited through a 475+/240 nm band pass filter and fluorescence emission was collected through a 515+/220 nm band pass filter. Analysis is performed using microscopical methods such as High Content Analysis (Anguissola et al., 2014). This method as well as use of LysoSensor probes has been reported repeatedly elsewhere, for example (Wang et al., 2013; Kroemer and Jäättelä, 2005). 

More specific staining can be achieved by staining with antibodies against lysosomal membrane proteins (Kroemer and Jäättelä, 2005). 

Lysosomal membrane permeabilization can be visualized by immunostaining of lysosomal enzymes such as cathepsin B (Boya et al. 2003a).

Domain of Applicability

This free text section should be used to elaborate on the scientific basis for the indicated domains of applicability and the WoE calls (if provided). While structured terms may be selected to define the taxonomic, life stage and sex applicability (see structured applicability terms, above) of the KE, the structured terms may not adequately reflect or capture the overall biological applicability domain (particularly with regard to taxa). Likewise, the structured terms do not provide an explanation or rationale for the selection. The free-text section on evidence for taxonomic, life stage, and sex applicability can be used to elaborate on why the specific structured terms were selected, and provide supporting references and background information.  More help

Typically, human or murine cell lines are used to assess this event. Examples are

 murine (Reiners et al., 2002)

murine, human (Li et al., 2000)

murine, human (Ghosh et al., 2011)

human (Loos et al., 2014)

human, murine (Anguissola et al., 2014)

human (Hamacher-Brady et al., 2011)


List of the literature that was cited for this KE description. Ideally, the list of references, should conform, to the extent possible, with the OECD Style Guide ( (OECD, 2015). More help

Anguissola S, Garry D, Salvati A, O'Brien PJ, Dawson KA. High content analysis provides mechanistic insights on the pathways of toxicity induced by amine-modified polystyrene nanoparticles. PLoS One. (2014) 9(9):e108025.

Antunes F, Cadenas E, Brunk UT. Apoptosis induced by exposure to a low steady-state concentration of H2O2 is a consequence of lysosomal rupture. Biochemical Journal. (2001) 356(Pt 2):549-555.

Boya P,  Andreau K, Poncet D,  Zamzami N, Perfettini JL, Metivier D, Ojcius DM,  Jäättelä M, Kroemer G. Lysosomal membrane permeabilization induces cell death in a mitochondrion-dependent fashion, J. Exp. Med. (2003) 197:1323–1334.

Boya P, Gonzalez-Polo RA, Poncet D,  Andreau K, Vieira HL,  Roumier T, Perfettini JL, Kroemer G. Mitochondrial membrane permeabilization is a critical step of lysosome-initiated apoptosis induced by hydroxychloroquine, Oncogene (2003) 22:3927–3936.

Bursch W. The autophagosomal-lysosomal compartment in programmed cell death. Cell Death Differ. (2001) 8(6):569-81.

Cho W-S, Duffin R, Howie SEM, Scotton CJ, Wallace WAH, Macnee W, Bradley M, Megson IL, Donaldson K. Progressive severe lung injury by zinc oxide nanoparticles; the role of Zn2+ dissolution inside lysosomes. Part Fibre Toxicol (2011) 8:27.

Cho W-S, Duffin R, Thielbeer F, Bradley M, Megson IL, MacNee W, Poland CA, Tran CL, Donaldson K. Zeta potential and solubility to toxic ions as mechanisms of lung inflammation caused by metal/metal oxide nanoparticles. Toxicol Sci (2012) 126:469–477.

Cirman T, Oresić K, Droga-Mazovec G, Turk V, Reed JC, Myers RM, Salvesen GS, Turk B. Selective disruption of lysosomes in HeLa cells triggers apoptosis mediated by cleavage of Bid by multiple papain-like lysosomal cathepsins. J Biol Chem. (2004) 279(5): 3578–3587.

de Duve C, Pressman BC, Gianetto R, Wattiaux R, Applemans F. Tissue fractionation studies. 6. Intracellular distribution patterns of enzymes in rat-liver tissue. Biochem J. (1955) 60(4):604-17.

Droga-Mazovec G, Bojič L, Petelin A, Ivanova S, Romih R, Repnik U, Salvesen GS, Stoka V, Turk V, Turk B. Cysteine cathepsins trigger caspase-dependent cell death through cleavage of bid and antiapoptotic Bcl-2 homologues, J. Biol. Chem. (2008) 283:19140–19150.

Ghosh M, Carlsson F, Laskar A, Yuan XM, Li W. Lysosomal membrane permeabilization causes oxidative stress and ferritin induction in macrophages. FEBS Lett. (2011) 585(4):623-9.

Goldman R, Kaplan A. Rupture of rat liver lysosomes mediated by L-amino acid esters, Biochim. Biophys. Acta  1973, 318: 205–216.

Guicciardi ME, Leist M, Gores GJ. Lysosomes in cell death. Oncogene. (2004) 23(16):2881-90.

Hamacher-Brady A, Stein HA, Turschner S, Toegel I, Mora R, Jennewein N, Efferth T, Eils R, Brady NR. Artesunate activates mitochondrial apoptosis in breast cancer cells via iron-catalyzed lysosomal reactive oxygen species production. J Biol Chem. (2011) 286(8):6587-601.

Ishidoh K, Kominami E. Processing and activation of lysosomal proteinases. Biol Chem. (2002)  383(12): 1827–1831.

Johansson AC, Appelqvist H, Nilsson C, Kågedal K, Roberg K, Ollinger K. Regulation of apoptosis-associated lysosomal membrane permeabilization. Apoptosis. (2010) 15(5):527-40.

Kagedal K, Zhao M, Svensson I, Brunk UT. Sphingosine-induced apoptosis is dependent on lysosomal proteases. The Biochemical journal.  (2001) 359:335-43.

Kroemer G, Jäättelä M. Lysosomes and autophagy in cell death control. Nat Rev Cancer. (2005) 5(11):886-97.

Kubota C, Torii S, Hou N, Saito N, Yoshimoto Y, Imai H, Takeuchi T. Constitutive reactive oxygen species generation from autophagosome/lysosome in neuronal oxidative toxicity. J Biol Chem. (2010) 285(1):667-74.

Kurz T, Terman A, Gustafsson B, Brunk  UT.  Lysosomes in iron metabolism, ageing and apoptosis. Histochem. Cell Biol. (2008) 129: 389-406.

Li W, Yuan X, Nordgren G, Dalen H, Dubowchik GM, Firestone RA, Brunk UT. Induction of cell death by the lysosomotropic detergent MSDH, FEBS Lett. (2000) 470:35–39.

Loos C, Syrovets T, Musyanovych A, Mailänder V, Landfester K, Nienhaus GU, Simmet T. Functionalized polystyrene nanoparticles as a platform for studying bio-nano interactions. Beilstein J Nanotechnol. (2014) 5:2403-12.

Ostenfeld MS, Fehrenbacher N, Høyer-Hansen M, Thomsen C,  Farkas T,  Jäättelä M. Effective tumor cell death by sigma-2 receptor ligand siramesine involves lysosomal leakage and oxidative stress, Cancer Res. (2005) 65:8975–8983.

Reiners J, Caruso J, Mathieu P, Chelladurai B, Yin X-M, Kessel D. Release of cytochrome c and activation of pro-caspase-9 following lysosomal photodamage involves bid cleavage. Cell death and differentiation. (2002) 9(9):934-944.

Repnik U, Turk B. Lysosomal-mitochondrial cross-talk during cell death. Mitochondrion. (2010) 10(6):662-9.

Sumoza-Toledo A, Penner R. TRPM2: a multifunctional ion channel for calcium signalling. J. Physiol. (2011) 589:1515-1525.

Terman A, Kurz T, Navratil M, Arriaga EA, Brunk UT. Mitochondrial turnover and aging of long-lived postmitotic cells: the mitochondrial-lysosomal axis theory of aging. Antioxid Redox Signal. (2010) 12(4):503-35.

Uchimoto T, Nohara H, Kamehara R, Iwamura M, Watanabe N, Kobayashi Y. Mechanism of apoptosis induced by a lysosomotropic agent, L-Leucyl-L-Leucine methyl ester, Apoptosis (1999) 4:357–362.

Wang F, Bexiga MG, Anguissola S, Boya P, Simpson JC, Salvati A, Dawson KA: Time resolved study of cell death mechanisms induced by amine-modified polystyrene nanoparticles. Nanoscale (2013) 5:10868–76.

Wang F, Salvati A, Boya P. Lysosome-dependent cell death and deregulated autophagy induced by amine-modified polystyrene nanoparticles. Open Biol. (2018) 8(4): 170271.

Werneburg NW, Guicciardi ME, Bronk SF, Gores GJ. Tumor necrosis factor-alpha-associated lysosomal permeabilization is cathepsin B dependent. Am J Physiol Gastrointest Liver Physiol. (2002) 283:G947–G956.

Wilson PD, Firestone RA, Lenard J. The role of lysosomal enzymes in killing of mammalian cells by the lysosomotropic detergent N-dodecylimidazole, J. Cell. Biol. (1987) 104:1223–1229.

Zhao M, Brunk UT, Eaton JW. Delayed oxidant-induced cell death involves activation of phospholipase A2. FEBS Lett. (2001) 509:399–404.

Zhao M, Eaton JW,  Brunk UT. Bcl-2 phosphorylation is required for inhibition of oxidative stress induced lysosomal leak and ensuing apoptosis. FEBS Lett. (2001) 509: 405–412.