Proliferation of Lung Epithelial Cells Is Regulated by the Mechanisms of Autophagy Upon Exposure of Soots

BackgroundSoots are known to cause many diseases in humans, but their underlying mechanisms of toxicity are still not known. Here, we report that soots induce cell proliferation of lung epithelial cells via modulating autophagy pathways.ResultsFullerene soot and diesel exhaust particles (DEP) induced cell proliferation of lung epithelial, A549 cells via distinct autophagic mechanisms and did not cause cell death. Exposure of fullerene soot protected the cell death of A549 cells, caused by hydrogen peroxide, and inhibited LPS-induced autophagy. Fullerene soot co-localized with the autophagic proteins and inhibited starvation-induced autophagy (downregulated ATG-5, beclin-1, p62, and LC3 expressions) independent of its antioxidant properties. Similarly, it decreased the expression profile of autophagic genes and upregulated the proliferation-responsive gene, Ki-67, in mice. We observed that expressions of fullerene soot-responsive genes (Beclin-1, ATG-5, and p62) were reverted by Akt Inhibitor X, indicating an important role of the Akt pathway. At an elemental level, we found that elemental carbon of fullerene soot may be converted into organic carbon, as measured by OCEC, which may point fullerene soot as a source of carbon. On the other hand, DEP upregulated the expressions of autophagy genes. Akt Inhibitor X did not attenuate DEP-induced cell proliferation and autophagic response. However, an autophagic inhibitor, chloroquine, and significantly inhibited DEP-induced cell proliferation.ConclusionIt can be said that distinct autophagic mechanisms are operational in cell proliferation of lung epithelial cells due to soots, which may be responsible for different diseases. Understanding the mechanism of these pathways provides some important targets, which can be utilized for the development of future therapeutics.

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Proliferation of lung epithelial cells is regulated by the mechanisms of autophagy upon exposure of soots

10.1101/2020.09.19.304725 ◽

2020 ◽

Author(s):

Rituraj Niranjan ◽

Kaushal Prasad Mishra ◽

Ashwani Kumar Thakur

Keyword(s):

Cell Proliferation ◽

Cell Death ◽

Epithelial Cells ◽

Antioxidant Properties ◽

A549 Cells ◽

Beclin 1 ◽

Lung Epithelial Cells ◽

Akt Inhibitor ◽

Fullerene Soot ◽

Lung Epithelial

AbstractSoots are known to cause many diseases in humans but their underlying mechanisms of toxicity are still not known. Here, we report that, soots induce cell proliferation of lung epithelial cells via modulating autophagic pathways. Fullerene soot and diesel exhaust particles (DEP) induced cell proliferation of lung epithelial, A549 cells, via distinct autophagic mechanisms and did not cause cell death. Exposure of fullerene soot protected cell death of A549 cells, caused by hydrogen peroxide and inhibited LPS-induced autophagy. Fullerene soot co-localize with the autophagic proteins and inhibited starvation-induced autophagy (downregulated ATG-5, beclin-1, p62 and LC3 expressions) independent of its antioxidant properties. Similarly, it decreased expression profile of autophagic genes and upregulated proliferation responsive gene, Ki-67, in mice. We observed that, expressions of fullerene soot responsive genes (Beclin-1, ATG-5 and p62) were reverted by Akt Inhibitor X, indicating an important role of Akt pathway. On the other hand, DEP up-regulated expressions of autophagy genes. Akt Inhibitor X and Etoricoxib, did not attenuate DEP-induced cell proliferation and autophagic response. However, autophagic inhibiter 3-MA and chloroquine has significantly inhibited DEP-induced cell roliferation. In conclusion, distinct autophagic mechanisms are operational in cell proliferation of lung epithelial cells in response to soots and may have implication in diseases. The proliferation inducing potential of fullerene soot may be utilized as a regenerative agent in autophagy-associated disorders.

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Carbon nanoparticle-induced lung epithelial cell proliferation is mediated by receptor-dependent Akt activation

AJP Lung Cellular and Molecular Physiology ◽

10.1152/ajplung.00323.2007 ◽

2008 ◽

Vol 294 (2) ◽

pp. L358-L367 ◽

Cited By ~ 50

Author(s):

Klaus Unfried ◽

Ulrich Sydlik ◽

Katrin Bierhals ◽

Alexander Weissenberg ◽

Josef Abel

Keyword(s):

Cell Proliferation ◽

Epithelial Cells ◽

Carbon Nanoparticles ◽

Growth Factor Receptor ◽

Lung Epithelial Cells ◽

Alveolar Type ◽

Specific Cell ◽

Akt Inhibitor ◽

Signaling Mechanism ◽

Lung Epithelial

Treatment of lung epithelial cells with different kinds of nano-sized particles leads to cell proliferation. Because bigger particles fail to induce this reaction, it is suggested that the special surface properties, due to the extremely small size of these kinds of materials, is the common principle responsible for this specific cell reaction. Here the activation of the protein kinase B (Akt) signaling cascade by carbon nanoparticles was investigated with regard to its relevance for proliferation. Kinetics and dose-response experiments demonstrated that Akt is specifically activated by nanoparticulate carbon particles in rat alveolar type II epithelial cells as well as in human bronchial epithelial cells. This pathway appeared to be dependent on epidermal growth factor receptor and β1-integrins. The activation of Akt by these receptors is known to be a feature of adhesion-dependent signaling. However, intracellular proteins described in this context (focal adhesion kinase pp125FAK and integrin-linked kinase) were not activated, indicating a specific signaling mechanism. Inhibitor studies demonstrate that nanoparticle-induced proliferation is mediated by phosphoinositide 3-kinases and Akt. Moreover, overexpression of mutant Akt, as well as pretreatment with an Akt inhibitor, reduced nanoparticle-specific ERK1/2 phosphorylation, which is decisive for nanoparticle-induced proliferation. With this report, we describe the activation of a pathway by carbon nanoparticles that was so far known to be triggered by ligand receptor binding or on cell adhesion to extracellular matrix proteins.

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Amphiregulin induces interleukin-8 production and cell proliferation in lung epithelial cells through PI3K-Akt/ ERK pathways

European Journal of Inflammation ◽

10.1177/2058739221998202 ◽

2021 ◽

Vol 19 ◽

pp. 205873922199820

Author(s):

Fangfang Yang ◽

Wei Xu ◽

Yanli Pei

Keyword(s):

Cell Proliferation ◽

Epithelial Cells ◽

A549 Cells ◽

Specific Inhibitor ◽

Neutralizing Antibody ◽

Lung Epithelial Cells ◽

Signal Pathways ◽

Lung Epithelial ◽

Epidermal Growth

Amphiregulin (AR), belongs to the epidermal growth factor (EGF) family, is able to induce a series of pathological and physiological responses by binding and activating epidermal growth factor receptor (EGFR). Interleukin-8 (IL-8) or CXCL8, a pro-inflammatory chemokine, has been suggested to be involved in tumor cell proliferation and inflammatory microenvironment via transactivation of the EGFR. However, whether there is a crosstalk between AR with IL-8 during inflammatory response remain to be fully understood. The current study was designed to investigate the possible mechanism of the interactions between AR and IL-8 production in human lung epithelial cells in vitro. Lung epithelial A549 cells were stimulated with lipopolysaccharide (LPS) to generate ALI model. LPS-induced AR and IL-8 production by A549 cells was measured by real-time PCR, Western Blot, and ELISA. The AR neutralizing antibody, PI3K specific inhibitor LY294002, JNK specific inhibitor SP60012, ERK specific inhibitor PD98089, and p38 inhibitor SB203580 were used to investigate the role of these signal pathways in LPS-induced cell proliferation, AR and IL-8 expression. LPS could induce AR through PI3K/Akt and ERK signal pathways. Furthermore, LPS induced AR promoted the production of IL-8 requires activation of EGFR, PI3K/Akt, and ERK signal pathways. The neutralizing antibody to AR prevented production of IL-8 induced by LPS. Treatment with Erlotinib, PI3K inhibitors, ERK inhibitor significantly inhibited AR-induced IL-8 production and cell proliferation. Our data indicate that a distinct role of EGFR–PI3K–Akt/ERK pathway as a bridge of interaction between AR and IL-8 production, as one of potential mechanisms to regulate inflammation and cell proliferation in human lung epithelial cells.

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Mitochondrial aldehyde dehydrogenase attenuates hyperoxia-induced cell death through activation of ERK/MAPK and PI3K-Akt pathways in lung epithelial cells

AJP Lung Cellular and Molecular Physiology ◽

10.1152/ajplung.00045.2006 ◽

2006 ◽

Vol 291 (5) ◽

pp. L966-L975 ◽

Cited By ~ 50

Author(s):

Dong Xu ◽

Jill R. Guthrie ◽

Sherry Mabry ◽

Thomas M. Sack ◽

William E. Truog

Keyword(s):

Cell Death ◽

Epithelial Cells ◽

Cell Survival ◽

A549 Cells ◽

Lung Epithelial Cells ◽

Necrotic Cell Death ◽

Necrotic Cell ◽

Erk Phosphorylation ◽

Hyperoxic Exposure ◽

Lung Epithelial

Oxygen toxicity is one of the major risk factors in the development of the chronic lung disease or bronchopulmonary dysplasia in premature infants. Using proteomic analysis, we discovered that mitochondrial aldehyde dehydrogenase (mtALDH or ALDH2) was downregulated in neonatal rat lung after hyperoxic exposure. To study the role of mtALDH in hyperoxic lung injury, we overexpressed mtALDH in human lung epithelial cells (A549) and found that mtALDH significantly reduced hyperoxia-induced cell death. Compared with control cells (Neo-A549), the necrotic cell death in mtALDH-overexpressing cells (mtALDH-A549) decreased from 25.3 to 6.5%, 50.5 to 9.1%, and 52.4 to 15.1% after 24-, 48-, and 72-h hyperoxic exposure, respectively. The levels of intracellular and mitochondria-derived reactive oxygen species (ROS) in mtALDH-A549 cells after hyperoxic exposure were significantly lowered compared with Neo-A549 cells. mtALDH overexpression significantly stimulated extracellular signal-regulated kinase (ERK) phosphorylation under normoxic and hyperoxic conditions. Inhibition of ERK phosphorylation partially eliminated the protective effect of mtALDH in hyperoxia-induced cell death, suggesting ERK activation by mtALDH conferred cellular resistance to hyperoxia. mtALDH overexpression augmented Akt phosphorylation and maintained the total Akt level in mtALDH-A549 cells under normoxic and hyperoxic conditions. Inhibition of phosphatidylinositol 3-kinase (PI3K) activation by LY294002 in mtALDH-A549 cells significantly increased necrotic cell death after hyperoxic exposure, indicating that PI3K-Akt activation by mtALDH played an important role in cell survival after hyperoxia. Taken together, these data demonstrate that mtALDH overexpression attenuates hyperoxia-induced cell death in lung epithelial cells through reduction of ROS, activation of ERK/MAPK, and PI3K-Akt cell survival signaling pathways.

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Characterization of Nitric Oxide (NO)-Induced Cell Death in Lung Epithelial Cells

Tuberculosis and Respiratory Diseases ◽

10.4046/trd.2004.56.2.187 ◽

2004 ◽

Vol 56 (2) ◽

pp. 187

Author(s):

Wha Shim Yong ◽

Youn Seup Kim ◽

Jae Seuk Park ◽

Young Koo Jee ◽

Kye Young Lee

Keyword(s):

Nitric Oxide ◽

Cell Death ◽

Epithelial Cells ◽

Lung Epithelial Cells ◽

Lung Epithelial

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Ionizing radiation enhances matrix metalloproteinase-2 production in human lung epithelial cells

AJP Lung Cellular and Molecular Physiology ◽

10.1152/ajplung.2001.280.1.l30 ◽

2001 ◽

Vol 280 (1) ◽

pp. L30-L38 ◽

Cited By ~ 41

Author(s):

Jun Araya ◽

Muneharu Maruyama ◽

Kazuhiko Sassa ◽

Tadashi Fujita ◽

Ryuji Hayashi ◽

...

Keyword(s):

Epithelial Cells ◽

Ionizing Radiation ◽

Basement Membrane ◽

Lung Injury ◽

Human Lung ◽

A549 Cells ◽

Lung Epithelial Cells ◽

Lung Epithelial ◽

Radiation Induced ◽

Human Lung Epithelial Cells

Radiation pneumonitis is a major complication of radiation therapy. However, the detailed cellular mechanisms have not been clearly defined. Based on the recognition that basement membrane disruption occurs in acute lung injury and that matrix metalloproteinase (MMP)-2 can degrade type IV collagen, one of the major components of the basement membrane, we hypothesized that ionizing radiation would modulate MMP-2 production in human lung epithelial cells. To evaluate this, the modulation of MMP-2 with irradiation was investigated in normal human bronchial epithelial cells as well as in A549 cells. We measured the activity of MMP-2 in the conditioned medium with zymography and the MMP-2 mRNA level with RT-PCR. Both of these cells constitutively expressed 72-kDa gelatinolytic activity, corresponding to MMP-2, and exposure to radiation increased this activity. Consistent with the data of zymography, ionizing radiation increased the level of MMP-2 mRNA. This radiation-induced increase in MMP-2 expression was mediated via p53 because the p53 antisense oligonucleotide abolished the increase in MMP-2 activity as well as the accumulation of p53 after irradiation in A549 cells. These results indicate that MMP-2 expression by human lung epithelial cells is involved in radiation-induced lung injury.

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TRIM28 regulates SARS-CoV-2 cell entry by targeting ACE2

10.1101/2020.08.12.247825 ◽

2020 ◽

Author(s):

Yinfang Wang ◽

Yingzhe Fan ◽

Yitong Huang ◽

Tao Du ◽

Zongjun Liu ◽

...

Keyword(s):

Epithelial Cells ◽

Nk Cells ◽

Interleukin 2 ◽

A549 Cells ◽

Endogenous Retrovirus ◽

Alveolar Epithelial Cells ◽

Cell Entry ◽

Lung Epithelial Cells ◽

Lung Epithelial ◽

Ifn Γ

AbstractSevere acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the cause of coronavirus disease 2019 (COVID-19), it binds to angiotensin-converting enzyme 2 (ACE2) to enter into human cells. The expression level of ACE2 potentially determine the susceptibility and severity of COVID-19, it is thus of importance to understand the regulatory mechanism of ACE2 expression. Tripartite motif containing 28 (TRIM28) is known to be involved in multiple processes including antiviral restriction, endogenous retrovirus latency and immune response, it is recently reported to be co-expressed with SARS-CoV-2 receptor in type II pneumocytes; however, the roles of TRIM28 in ACE2 expression and SARS-CoV-2 cell entry remain unclear. This study showed that knockdown of TRIM28 induces ACE2 expression and increases pseudotyped SARS-CoV-2 cell entry of A549 cells and primary pulmonary alveolar epithelial cells (PAEpiCs). In a co-culture model of NK cells and lung epithelial cells, our results demonstrated that NK cells inhibit TRIM28 and promote ACE2 expression in lung epithelial cells, which was partially reversed by depletion of interleukin-2 and blocking of granzyme B in the co-culture medium. Furthermore, TRIM28 knockdown enhanced interferon-γ (IFN-γ)-induced ACE2 expression through a mechanism involving upregulating IFN-γ receptor 2 (IFNGR2) in both A549 and PAEpiCs. Importantly, the upregulated ACE2 induced by TRIM28 knockdown and co-culture of NK cells was partially reversed by dexamethasone in A549 cells but not PAEpiCs. Our study identified TRIM28 as a novel regulator of ACE2 expression and SARS-CoV-2 cell entry.

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Dual mechanism forMycobacterium tuberculosiscytotoxicity on lung epithelial cells

Canadian Journal of Microbiology ◽

10.1139/w2012-067 ◽

2012 ◽

Vol 58 (7) ◽

pp. 909-916 ◽

Cited By ~ 5

Author(s):

Jorge Castro-Garza ◽

W. Edward Swords ◽

Russell K. Karls ◽

Frederick D. Quinn

Keyword(s):

Epithelial Cell ◽

Epithelial Cells ◽

Neutralizing Antibodies ◽

Cytotoxic Effect ◽

Alveolar Epithelial Cell ◽

A549 Cells ◽

Lung Epithelial Cells ◽

Necrosis Factor Alpha ◽

Tnf Α ◽

Lung Epithelial

Mycobacterium tuberculosis strains CDC1551 and Erdman were used to assess cytotoxicity in infected A549 human alveolar epithelial cell monolayers. Strain CDC1551 was found to induce qualitatively greater disruption of A549 monolayers than was strain Erdman, although total intracellular and cell-associated bacterial growth rates over the course of the infections were not significantly different. Cell-free culture supernatants from human monocytic cells infected with either of the 2 M. tuberculosis strains produced a cytotoxic effect on A549 cells, correlating with the amount of tumor necrosis factor alpha (TNF-α) released by the infected monocytes. The addition of TNF-α-neutralizing antibodies to the supernatants from infected monocyte cultures did prevent the induction of a cytotoxic effect on A549 cells overlaid with this mixture but did not prevent the death of epithelial cells when added prior to infection with M. tuberculosis bacilli. Thus, these data agree with previous observations that lung epithelial cells infected with M. tuberculosis bacilli are rapidly killed in vitro. In addition, the data indicate that some of the observed epithelial cell killing may be collateral damage; the result of TNF-α released from M. tuberculosis-infected monocytes.

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Role of Nucleolin in Human Parainfluenza Virus Type 3 Infection of Human Lung Epithelial Cells

Journal of Virology ◽

10.1128/jvi.78.15.8146-8158.2004 ◽

2004 ◽

Vol 78 (15) ◽

pp. 8146-8158 ◽

Cited By ~ 51

Author(s):

Santanu Bose ◽

Mausumi Basu ◽

Amiya K. Banerjee

Keyword(s):

Epithelial Cells ◽

Cell Surface ◽

Human Lung ◽

A549 Cells ◽

Lung Epithelial Cells ◽

Parainfluenza Virus ◽

Lung Epithelial ◽

Human Parainfluenza Virus ◽

Type 3 ◽

Human Lung Epithelial Cells

ABSTRACT Human parainfluenza virus type 3 (HPIV-3) is an airborne pathogen that infects human lung epithelial cells from the apical (luminal) plasma membrane domain. In the present study, we have identified cell surface-expressed nucleolin as a cellular cofactor required for the efficient cellular entry of HPIV-3 into human lung epithelial A549 cells. Nucleolin was enriched on the apical cell surface domain of A549 cells, and HPIV-3 interacted with nucleolin during entry. The importance of nucleolin during HPIV-3 replication was borne out by the observation that HPIV-3 replication was significantly inhibited following (i) pretreatment of cells with antinucleolin antibodies and (ii) preincubation of HPIV-3 with purified nucleolin prior to its addition to the cells. Moreover, HPIV-3 cellular internalization and attachment assays performed in the presence of antinucleolin antibodies and purified nucleolin revealed the requirement of nucleolin during HPIV-3 internalization but not during attachment. Thus, these results suggest that nucleolin expressed on the surfaces of human lung epithelial A549 cells plays an important role during HPIV-3 cellular entry.

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