Kinetics of autophagic activity in nanoparticle-exposed lung adenocarcinoma (A549) cells
Autophagy, a homeostatic mechanism, is crucial in maintaining normal cellular function. Although dysregulation of autophagic processes is recognized in certain diseases, it is unknown how maintenance of cellular homeostasis might be affected by the kinetics of autophagic activity in response to vari...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
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Taylor & Francis Group
2023-12-01
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| Series: | Autophagy Reports |
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| Online Access: | http://dx.doi.org/10.1080/27694127.2023.2186568 |
| _version_ | 1827818539822612480 |
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| author | Arnold Sipos Kwang-Jin Kim Constantinos Sioutas Edward D. Crandall |
| author_facet | Arnold Sipos Kwang-Jin Kim Constantinos Sioutas Edward D. Crandall |
| author_sort | Arnold Sipos |
| collection | DOAJ |
| description | Autophagy, a homeostatic mechanism, is crucial in maintaining normal cellular function. Although dysregulation of autophagic processes is recognized in certain diseases, it is unknown how maintenance of cellular homeostasis might be affected by the kinetics of autophagic activity in response to various stimuli. In this study, we assessed those kinetics in lung adenocarcinoma (A549) cells in response to exposure to nanoparticles (NP) and/or Rapamycin. Since NP are known to induce autophagy, we wished to determine if this phenomenon could be a driver of the harmful effects seen in lung tissues exposed to air pollution. A549 cells were loaded with a fluorescent marker (DAPRed) that labels autophagosomes and autolysosomes. Autophagic activity was assessed based on the fluorescence intensity of DAPRed measured over the entire cell volume of live single cells using confocal laser scanning microscopy (CLSM). Autophagic activity over time was determined during exposure of A549 cells to single agents (50 nM Rapamycin; 80 μg/mL, 20 nm carboxylated polystyrene NP (PNP); or, 1 μg/mL ambient ultrafine particles (UFP) (<180 nm)), or double agents (Rapamycin + PNP or Rapamycin + UFP; concomitant and sequential), known to stimulate autophagy. Autophagic activity increased in all experimental modalities, including both single agent and double agent exposures, and reached a steady state in all cases ~2 times control from ~8 to 24 hrs, suggesting the presence of an upper limit to autophagic capacity. These results are consistent with the hypothesis that environmental stressors might exert their harmful effects, at least in part, by limiting available autophagic response to additional stimulation, thereby making nanoparticle-exposed cells more susceptible to secondary injury due to autophagic overload. |
| first_indexed | 2024-03-12T00:55:13Z |
| format | Article |
| id | doaj.art-78ace855f2a44565ac164e44a4676e79 |
| institution | Directory Open Access Journal |
| issn | 2769-4127 |
| language | English |
| last_indexed | 2024-03-12T00:55:13Z |
| publishDate | 2023-12-01 |
| publisher | Taylor & Francis Group |
| record_format | Article |
| series | Autophagy Reports |
| spelling | doaj.art-78ace855f2a44565ac164e44a4676e792023-09-14T13:24:41ZengTaylor & Francis GroupAutophagy Reports2769-41272023-12-012110.1080/27694127.2023.21865682186568Kinetics of autophagic activity in nanoparticle-exposed lung adenocarcinoma (A549) cellsArnold Sipos0Kwang-Jin Kim1Constantinos Sioutas2Edward D. Crandall3Will Rogers Institute Pulmonary Research Center and Hastings Center for Pulmonary Research, Keck School of Medicine, University of Southern CaliforniaWill Rogers Institute Pulmonary Research Center and Hastings Center for Pulmonary Research, Keck School of Medicine, University of Southern CaliforniaViterbi School of Engineering, University of Southern CaliforniaWill Rogers Institute Pulmonary Research Center and Hastings Center for Pulmonary Research, Keck School of Medicine, University of Southern CaliforniaAutophagy, a homeostatic mechanism, is crucial in maintaining normal cellular function. Although dysregulation of autophagic processes is recognized in certain diseases, it is unknown how maintenance of cellular homeostasis might be affected by the kinetics of autophagic activity in response to various stimuli. In this study, we assessed those kinetics in lung adenocarcinoma (A549) cells in response to exposure to nanoparticles (NP) and/or Rapamycin. Since NP are known to induce autophagy, we wished to determine if this phenomenon could be a driver of the harmful effects seen in lung tissues exposed to air pollution. A549 cells were loaded with a fluorescent marker (DAPRed) that labels autophagosomes and autolysosomes. Autophagic activity was assessed based on the fluorescence intensity of DAPRed measured over the entire cell volume of live single cells using confocal laser scanning microscopy (CLSM). Autophagic activity over time was determined during exposure of A549 cells to single agents (50 nM Rapamycin; 80 μg/mL, 20 nm carboxylated polystyrene NP (PNP); or, 1 μg/mL ambient ultrafine particles (UFP) (<180 nm)), or double agents (Rapamycin + PNP or Rapamycin + UFP; concomitant and sequential), known to stimulate autophagy. Autophagic activity increased in all experimental modalities, including both single agent and double agent exposures, and reached a steady state in all cases ~2 times control from ~8 to 24 hrs, suggesting the presence of an upper limit to autophagic capacity. These results are consistent with the hypothesis that environmental stressors might exert their harmful effects, at least in part, by limiting available autophagic response to additional stimulation, thereby making nanoparticle-exposed cells more susceptible to secondary injury due to autophagic overload.http://dx.doi.org/10.1080/27694127.2023.2186568autophagyautophagic capacityambient ultrafine particlespolystyrene nanoparticlesrapamycin |
| spellingShingle | Arnold Sipos Kwang-Jin Kim Constantinos Sioutas Edward D. Crandall Kinetics of autophagic activity in nanoparticle-exposed lung adenocarcinoma (A549) cells Autophagy Reports autophagy autophagic capacity ambient ultrafine particles polystyrene nanoparticles rapamycin |
| title | Kinetics of autophagic activity in nanoparticle-exposed lung adenocarcinoma (A549) cells |
| title_full | Kinetics of autophagic activity in nanoparticle-exposed lung adenocarcinoma (A549) cells |
| title_fullStr | Kinetics of autophagic activity in nanoparticle-exposed lung adenocarcinoma (A549) cells |
| title_full_unstemmed | Kinetics of autophagic activity in nanoparticle-exposed lung adenocarcinoma (A549) cells |
| title_short | Kinetics of autophagic activity in nanoparticle-exposed lung adenocarcinoma (A549) cells |
| title_sort | kinetics of autophagic activity in nanoparticle exposed lung adenocarcinoma a549 cells |
| topic | autophagy autophagic capacity ambient ultrafine particles polystyrene nanoparticles rapamycin |
| url | http://dx.doi.org/10.1080/27694127.2023.2186568 |
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