γ-Glutamylcysteine synthetase induction by cigarette smoke exposure in alveolar epithelial cells

Cigarette smoke mediates DNA damage, lipid peroxidation, and modification and misfolding of proteins, thereby inducing severe cellular damage. The ubiquitin proteasome system serves as the major disposal system for modified and misfolded proteins and is thus essential for proper cellular function. Its role in cigarette smoke-induced cell damage, however, is largely unknown. We hypothesized that the ubiquitin-proteasome system is involved in the degradation of cigarette smoke-damaged proteins and that cigarette smoke exposure impairs the proteasome itself. Here, we show that treatment of human alveolar epithelial cells with cigarette smoke extract (CSE) induced time- and dose-dependent cell death, a rise in intracellular reactive oxygen species, and increased levels of carbonylated and polyubiquitinated proteins. While high doses of CSE severely impaired all three proteasomal activities, low CSE concentrations significantly inhibited only the trypsin-like activity of the proteasome in alveolar and bronchial epithelial cells. Moreover, acute exposure of mice to cigarette smoke significantly impaired the trypsin-like activity by 25% in the lungs. Reduced proteasome activity was not due to transcriptional regulation of the proteasome. Notably, cigarette smoke exposure induced accumulation of polyubiquitinated proteins in the soluble and insoluble protein fraction of the lung. We show for the first time that acute exposure to cigarette smoke directly impairs proteasome activity in the lungs of mice and in human epithelial cells at low doses without affecting proteasome expression. Our results indicate that defective proteasomal protein quality control may exacerbate the detrimental effects of cigarette smoke in the lung.

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Induction of γ-glutamylcysteine synthetase by cigarette smoke is associated with AP-1 in human alveolar epithelial cells

FEBS Letters ◽

10.1016/0014-5793(96)01027-7 ◽

1996 ◽

Vol 396 (1) ◽

pp. 21-25 ◽

Cited By ~ 123

Author(s):

Irfan Rahman ◽

Christopher A.D. Smith ◽

Mark F. Lawson ◽

David J. Harrison ◽

William MacNee

Keyword(s):

Epithelial Cells ◽

Cigarette Smoke ◽

Alveolar Epithelial Cells ◽

Alveolar Epithelial ◽

Glutamylcysteine Synthetase ◽

Human Alveolar Epithelial Cells

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Differential regulation of glutathione by oxidants and dexamethasone in alveolar epithelial cells

AJP Lung Cellular and Molecular Physiology ◽

10.1152/ajplung.1998.275.1.l80 ◽

1998 ◽

Vol 275 (1) ◽

pp. L80-L86 ◽

Cited By ~ 11

Author(s):

Irfan Rahman ◽

Agnes Bel ◽

Brigitte Mulier ◽

Kenneth Donaldson ◽

William MacNee

Keyword(s):

Epithelial Cells ◽

Xanthine Oxidase ◽

Cigarette Smoke ◽

Control Level ◽

Alveolar Epithelial Cells ◽

Time Dependent ◽

Cigarette Smoke Condensate ◽

Alveolar Epithelial ◽

Glutamylcysteine Synthetase ◽

Glutamyl Transpeptidase

We studied the regulation of GSH and the enzymes involved in GSH regulation, γ-glutamylcysteine synthetase (γ-GCS) and γ-glutamyl transpeptidase (γ-GT), in response to the oxidants menadione, xanthine/xanthine oxidase, hyperoxia, and cigarette smoke condensate in human alveolar epithelial cells (A549). Menadione (100 μM), xanthine/xanthine oxidase (50 μM/10 mU), and cigarette smoke condensate (10%) exposure produced increased GSH levels (240 ± 6, 202 ± 12, and 191 ± 2 nmol/mg protein, respectively; P < 0.001) compared with the control level (132 ± 8 nmol/mg protein), which were associated with a significant increase in γ-GCS activity (0.18 ± 0.006, 0.16 ± 0.01, and 0.17 ± 0.008 U/mg protein, respectively; P < 0.01) compared with the control level (0.08 ± 0.001 U/mg protein) at 24 h. Exposure to hyperoxia (95% O2) resulted in a time-dependent increase in GSH levels. γ-GCS activity increased significantly at 4 h ( P < 0.001), returning to control values after 12 h of exposure. Dexamethasone (3 μM) exposure produced a significant time-dependent decrease in the levels of GSH and γ-GCS activity at 24–96 h. The activity of γ-GT did not change after oxidant treatment; however, it was decreased significantly by dexamethasone at 24–96 h. Thus oxidants and dexamethasone modulate GSH levels and activities of γ-GT and γ-GCS by different mechanisms. We suggest that the increase in γ-GCS activity but not in γ-GT activity may be required for the increase in intracellular GSH under oxidative stress in alveolar epithelial cells.

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Alveolar epithelial cells type II show a high sensitivity to cigarette smoke extract

Pneumologie ◽

10.1055/s-0034-1376780 ◽

2014 ◽

Vol 68 (06) ◽

Author(s):

S Seehase ◽

B Baron-Luehr ◽

C Kugler ◽

E Vollmer ◽

T Goldmann

Keyword(s):

Epithelial Cells ◽

Cigarette Smoke ◽

High Sensitivity ◽

Cigarette Smoke Extract ◽

Alveolar Epithelial Cells ◽

Type Ii ◽

Alveolar Epithelial

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Senescence associated long non-coding RNA 1 regulates cigarette smoke-induced senescence of type II alveolar epithelial cells through sirtuin-1 signaling

Journal of International Medical Research ◽

10.1177/0300060520986049 ◽

2021 ◽

Vol 49 (2) ◽

pp. 030006052098604

Author(s):

Dong Yuan ◽

Yuanshun Liu ◽

Mengyu Li ◽

Hongbin Zhou ◽

Liming Cao ◽

...

Keyword(s):

Epithelial Cells ◽

Cigarette Smoke ◽

Alveolar Epithelial Cell ◽

Alveolar Epithelial Cells ◽

Lung Epithelial Cells ◽

Sirtuin 1 ◽

Type Ii ◽

Alveolar Epithelial ◽

Non Coding Rna ◽

Long Non Coding Rna

Objective The primary aim of our study was to explore the mechanisms through which long non-coding RNA (lncRNA)-mediated sirtuin-1 (SIRT1) signaling regulates type II alveolar epithelial cell (AECII) senescence induced by a cigarette smoke-media suspension (CSM). Methods Pharmacological SIRT1 activation was induced using SRT2104 and senescence-associated lncRNA 1 (SAL-RNA1) was overexpressed. The expression of SIRT1, FOXO3a, p53, p21, MMP-9, and TIMP-1 in different groups was detected by qRT-PCR and Western blotting; the activity of SA-β gal was detected by staining; the binding of SIRT1 to FOXO3a and p53 gene transcription promoters was detected by Chip. Results We found that CSM increased AECII senescence, while SAL-RNA1 overexpression and SIRT1 activation significantly decreased levels of AECII senescence induced by CSM. Using chromatin immunoprecipitation, we found that SIRT1 bound differentially to transcriptional complexes on the FOXO3a and p53 promoters. Conclusion Our results suggested that lncRNA-SAL1-mediated SIRT1 signaling reduces senescence of AECIIs induced by CSM. These findings suggest a new therapeutic target to limit the irreversible apoptosis of lung epithelial cells in COPD patients.

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