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endocytosis leads to Disruption, Lysosome
Key Event Relationship Overview
AOPs Referencing Relationship
|AOP Name||Adjacency||Weight of Evidence||Quantitative Understanding||Point of Contact||Author Status||OECD Status|
|Endocytic lysosomal uptake leading to liver fibrosis||adjacent||High||Marina Kuburic (send email)||Under development: Not open for comment. Do not cite||EAGMST Under Review|
Life Stage Applicability
|All life stages|
Key Event Relationship Description
Different substances can be uptaken by endocytosis and localized in lysosomes, while some of them can cause lysosomal disruption. Lysosomotropic agents are mostly weak, lipophilic bases that diffuse across lysosomal membrane, get protonated in the acidic milieu of lysosome and therefore get trapped inside (de Duve et al., 1974). They accumulate and cause the destabilization of lysosomal membranes by acting as surfactants, incorporating its hydrophobic tail in the membrane and with the hydrophilic head facing the interior of the lysosome (de Duve et al.,1974; Firestone et al.,1979). Their accumulation increase the intralysosomal pH, which has many consequences, including the prevention of the further uptake of lysosomotropic compounds, an increase in size and number of lysosomes and the overloading of lysosomes with non-digestible materials.
There are different mechanisms how lysosomotropic agents can disrupt lysosomal membrane. However, not all lysosomotropic agents disrupt lysosomes- for example ammonia salts, methylamine and related hydrophilic weak bases cause swelling of the lysosomes, but do not increase permeability of the membrane. Usually in order to do that, agent requires a certain degree of lipid solubility. The amine will accumulate in the lysosomes until its concentration is high enough to solubilize the lysosomal membrane (Dubowchik et al., 1995)
It has been demonstrated that as a result of protonated agents in lysosomes, there will be accumulation of non-permeable charged substances which will result in inflow of water by increased osmolarity (Bandyopadhyay et al., 2014). Inflow of water results in increase of size and can cause the rupture of lysosome.
Also, oxidative stress can cause destabilization of the lysosomal membrane and for this process, intra-lysosomal ferric ions are essential. They catalyse the formation of oxygen radicals from hydrogen peroxide (Zdoslek et al., 1993).
Evidence Supporting this KER
Trapping of lysosomotropic agents accumulates substances inside of the lysosomes, increases volume of these organelles, and big lysosomes are more prone to rupture (Ono et al., 2003). However, there are many mechanisms for lysosomotropic substances to provoke lysosomal disruption, but their prior uptake by lysosomes is essential.
Uncertainties and Inconsistencies
Known modulating factors
Known Feedforward/Feedback loops influencing this KER
Domain of Applicability
Mouse (Werneburg et al., 2002; Kagedal et al., 2001)
Rat (Jung et al., 2015)
Hamster (Hayashi et al., 2008)
Human (Wang et al., 2013)
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Brunk UT, Neuzil J, Eaton JW. Lysosomal involvement in apoptosis, Redox Report, (2001) 6 (2): 91-97.
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.
de Duve C, de Barsy T, Poole B, Trouet A, Tulkens P, Van Hoof F. Commentary. Lysosomotropic agents. Biochem. Pharmacol. (1974) 23:2495- 2531.
Dubowchik GM, Gawlak SL, Firestone RA. The in vitro effects of three lysosomotropic detergents against three human tumor cell lines Bioorg. Med. Chem. Lett. (1995) 5:893-898.
Firestone RA, Pisano JM, Bonney, RJ. Lysosomotropic agents. 1. Synthesis and cytotoxic action of lysosomotropic detergents. J. Med. Chem. (1979) 22: 1130- 1133.
Hayashi MAF, Nascimento FD, Kerkis A, Oliveira V, Oliveira EB, Pereira A, Rádis-Baptista G, Nader HB, Yamane T, Kerkis I, Tersariol ILS. Cytotoxic effects of crotamine are mediated through lysosomal membrane permeabilization. Toxicon. (2008) 52(3): 508–517.
Jung M, Lee J, Seo H-Y, Lim JS, Kim E-K. Cathepsin Inhibition-Induced Lysosomal Dysfunction Enhances Pancreatic Beta-Cell Apoptosis in High Glucose. PLoS ONE. (2015) 10(1):e011697.
Kagedal K, Zhao M, Svensson I, Brunk UT. Sphingosine-induced apoptosis is dependent on lysosomal proteases. The Biochemical journal. (2001) 359: 335-43.
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.
Ono K, Kim SO, Han J. Susceptibility of lysosomes to rupture is a determinant for plasma membrane disruption in tumor necrosis factor alpha-induced cell death. Mol Cell Biol. (2003) 23: 665-76.
Thiele DL, Lipsky PE. Mechanism of L-leucyl-L-leucine methyl ester-mediated killing of cytotoxic lymphocytes: dependence on a lysosomal thiol protease, dipeptidyl peptidase I, that is enriched in these cells. Proc Natl Acad Sci U S A. (1990) 87(1): 83–87.
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(5): 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.
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.
Zdolsek J, Zhang H, Roberg K, Brunk U, Sies H. H2O2-Mediated Damage to Lysosomal Membranes of J-774 Cells, Free Radical Research Communications, 1993, 18:2, 71-85