Norepinephrine induces alveolar epithelial apoptosis mediated by α-, β-, and angiotensin receptor activation

2001 ◽  
Vol 281 (3) ◽  
pp. L624-L630 ◽  
Author(s):  
H. Erhan Dincer ◽  
Nupur Gangopadhyay ◽  
Rongqi Wang ◽  
Bruce D. Uhal
Keyword(s):  
Enzyme Inhibitor ◽  
Primary Cultures ◽  
Cell Loss ◽  
Receptor Activation ◽  
Alveolar Epithelial Cells ◽  
Ang Ii ◽  
Alveolar Epithelial ◽  
Induced Apoptosis ◽  
Factor Α ◽  
20 Nm

Norepinephrine (NE) induces apoptosis in cardiac myocytes, and autocrine production of angiotensin (ANG) II is required for apoptosis of alveolar epithelial cells (AECs) (Wang R, Zagariya A, Ang E, Ibarra-Sunga O, and Uhal BD. Am J Physiol Lung Cell Mol Physiol 277: L1245–L1250, 1999; Wang R, Alam G, Zagariya A, Gidea C, Pinillos H, Lalude O, Choudhary G, and Uhal BD. J Cell Physiol 185: 253–259, 2000). On this basis, we hypothesized that NE might induce apoptosis of AECs in a manner inhibitable by ANG system antagonists. Purified NE induced apoptosis in the human A549 AEC-derived cell line or in primary cultures of rat AECs, with EC50 values of 200 and 20 nM, respectively. Neither the α-agonist phenylephrine nor the β-agonist isoproterenol could mimic NE when tested alone but when applied together could induce apoptosis with potency equal to NE. Apoptosis and net cell loss (47–59% in 40 h) in response to NE was completely abrogated by the ANG-converting enzyme inhibitor lisinopril or the ANG II receptor antagonist saralasin, each at concentrations capable of blocking Fas- or tumor necrosis factor-α-induced apoptosis. These data suggest that NE induces apoptosis of human and rat AECs through a mechanism involving the combination of α- and β-adrenoceptor activation followed by autocrine generation of ANG II.

Bleomycin-induced apoptosis of alveolar epithelial cells requires angiotensin synthesis de novo

2003 ◽  
Vol 284 (3) ◽  
pp. L501-L507 ◽  
Author(s):  
Xiaopeng Li ◽  
Huiying Zhang ◽  
Valerie Soledad-Conrad ◽  
Jiaju Zhuang ◽  
Bruce D. Uhal
Keyword(s):  
Epithelial Cells ◽  
Caspase 3 ◽  
De Novo ◽  
Enzyme Inhibitor ◽  
Primary Cultures ◽  
A549 Cells ◽  
Cell Loss ◽  
Alveolar Epithelial Cells ◽  
Alveolar Epithelial ◽  
Induced Apoptosis

Primary cultures of rat type II alveolar epithelial cells (AECs) or human AEC-derived A549 cells, when exposed to bleomycin (Bleo), exhibited concentration-dependent apoptosis detected by altered nuclear morphology, fragmentation of DNA, activation of caspase-3, and net cell loss over time. In both cell culture models, exposure to Bleo caused time-dependent increases in angiotensinogen (ANGEN) mRNA. Antisense oligonucleotides against ANGEN mRNA inhibited Bleo-induced apoptosis of rat AEC or A549 cells by 83 and 84%, respectively ( P < 0.01 and P < 0.05), and prevented Bleo-induced net cell loss. Apoptosis of rat AECs or A549 cells in response to Bleo was inhibited 91% by the ANG-converting enzyme inhibitor captopril or 82%, respectively, by neutralizing antibodies specific for ANG II (both P < 0.01). Antagonists of ANG receptor AT1 (losartan, L-158809, or saralasin), but not an AT2-selective blocker (PD-123319), inhibited Bleo-induced apoptosis of either rat AECs (79%, P < 0.01) or A549 cells (83%, P < 0.01) and also reduced the activity of caspase-3 by 52% ( P < 0.05). These data indicate that Bleo, like FasL or TNF-α, induces transactivation of ANG synthesis de novo that is required for AEC apoptosis. They also support the theory that ANG system antagonists have potential for the blockade of AEC apoptosis in situ.

Essential role for cathepsin D in bleomycin-induced apoptosis of alveolar epithelial cells

2004 ◽  
Vol 287 (1) ◽  
pp. L46-L51 ◽  
Author(s):  
Xiaopeng Li ◽  
Heather Rayford ◽  
Ruijie Shu ◽  
Jiaju Zhuang ◽  
Bruce D. Uhal
Keyword(s):  
Enzymatic Activity ◽  
Cathepsin D ◽  
Alveolar Epithelial Cells ◽  
Type Ii ◽  
Ang Ii ◽  
Nuclear Fragmentation ◽  
Alveolar Epithelial ◽  
Induced Apoptosis ◽  
Pepstatin A

Our earlier studies showed that bleomycin-induced apoptosis of type II alveolar epithelial cells (AECs) requires the autocrine synthesis and proteolytic processing of angiotensinogen into ANG II and that inhibitors of ANG-converting enzyme (ACEis) block bleomycin-induced apoptosis (Li X, Zhang H, Soledad-Conrad V, Zhuang J, and Uhal BD. Am J Physiol Lung Cell Mol Physiol 284: L501–L507, 2003). Given the documented role of cathepsin D (CatD) in apoptosis of other cell types, we hypothesized that CatD might be the AEC enzyme responsible for the conversion of angiotensinogen into ANG I, the substrate for ACE. Primary cultures of rat type II AECs challenged with bleomycin in vitro showed upregulation and secretion of CatD enzymatic activity and immunoreactive protein but no increases in CatD mRNA. The aspartyl protease inhibitor pepstatin A, which completely blocked CatD enzymatic activity, inhibited bleomycin-induced nuclear fragmentation by 76% and reduced bleomycin-induced caspase-3 activation by 47%. Antisense oligonucleotides against CatD mRNA reduced CatD-immunoreactive protein and inhibited bleomycin-induced nuclear fragmentation by 48%. A purified fragment of angiotensinogen (F1–14) containing the CatD and ACE cleavage sites, when applied to unchallenged AEC in vitro, yielded mature ANG II peptide and induced apoptosis. The apoptosis induced by F1–14 was inhibited 96% by pepstatin A and 77% by neutralizing antibodies specific for CatD (both P < 0.001). These data indicate a critical role for CatD in bleomycin-induced apoptosis of cultured AEC and suggest that the role(s) of CatD in AEC apoptosis include the conversion of newly synthesized angiotensinogen to ANG II.

scholarly journals Abrogation of ER stress-induced apoptosis of alveolar epithelial cells by angiotensin 1–7

2013 ◽  
Vol 305 (1) ◽  
pp. L33-L41 ◽  
Author(s):  
Bruce D. Uhal ◽  
Hang Nguyen ◽  
MyTrang Dang ◽  
Indiwari Gopallawa ◽  
Jing Jiang ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Er Stress ◽  
Cathepsin D ◽  
Primary Cultures ◽  
A549 Cells ◽  
Surfactant Protein ◽  
Alveolar Epithelial Cells ◽  
Alveolar Epithelial ◽  
Induced Apoptosis ◽  
Jnk Activation

Earlier work showed that apoptosis of alveolar epithelial cells (AECs) in response to endogenous or xenobiotic factors is regulated by autocrine generation of angiotensin (ANG) II and its counterregulatory peptide ANG1–7. Mutations in surfactant protein C (SP-C) induce endoplasmic reticulum (ER) stress and apoptosis in AECs and cause lung fibrosis. This study tested the hypothesis that ER stress-induced apoptosis of AECs might also be regulated by the autocrine ANGII/ANG1–7 system of AECs. ER stress was induced in A549 cells or primary cultures of human AECs with the proteasome inhibitor MG132 or the SP-C BRICHOS domain mutant G100S. ER stress activated the ANGII-generating enzyme cathepsin D and simultaneously decreased the ANGII-degrading enzyme ACE-2, which normally generates the antiapoptotic peptide ANG1–7. TAPI-2, an inhibitor of ADAM17/TACE, significantly reduced both the activation of cathepsin D and the loss of ACE-2. Apoptosis of AECs induced by ER stress was measured by assays of mitochondrial function, JNK activation, caspase activation, and nuclear fragmentation. Apoptosis induced by either MG132 or the SP-C BRICHOS mutant G100S was significantly inhibited by the ANG receptor blocker saralasin and was completely abrogated by ANG1–7. Inhibition by ANG1–7 was blocked by the specific mas antagonist A779. These data show that ER stress-induced apoptosis is mediated by the autocrine ANGII/ANG1–7 system in human AECs and demonstrate effective blockade of SP-C mutation-induced apoptosis by ANG1–7. They also suggest that therapeutic strategies aimed at administering ANG1–7 or stimulating ACE-2 may hold potential for the management of ER stress-induced fibrotic lung disorders.

Angiotensin II induces apoptosis in human and rat alveolar epithelial cells

1999 ◽  
Vol 276 (5) ◽  
pp. L885-L889 ◽  
Author(s):  
Rongqi Wang ◽  
Alex Zagariya ◽  
Olivia Ibarra-Sunga ◽  
Claudia Gidea ◽  
Edmund Ang ◽  
...  
Keyword(s):  
Angiotensin Ii ◽  
Epithelial Cells ◽  
Angiotensin Converting Enzyme ◽  
Enzyme Inhibitor ◽  
Alveolar Epithelial Cells ◽  
Receptor Subtypes ◽  
Ang Ii ◽  
Converting Enzyme ◽  
Alveolar Epithelial

Recent work from this laboratory demonstrated potent inhibition of apoptosis in human alveolar epithelial cells (AECs) by the angiotensin-converting enzyme inhibitor captopril [B. D. Uhal, C. Gidea, R. Bargout, A. Bifero, O. Ibarra-Sunga, M. Papp, K. Flynn, and G. Filippatos. Am. J. Physiol. 275 ( Lung Cell. Mol. Physiol. 19): L1013–L1017, 1998]. On this basis, we hypothesized that apoptosis in this cell type might be induced by angiotensin II (ANG II) through its interaction with the ANG II receptor. Purified ANG II induced dose-dependent apoptosis in both the human AEC-derived A549 cell line and in primary type II pneumocytes isolated from adult Wistar rats as detected by nuclear and chromatin morphology, caspase-3 activity, and increased binding of annexin V. Apoptosis also was induced in primary rat AECs by purified angiotensinogen. The nonselective ANG II-receptor antagonist saralasin completely abrogated both ANG II- and angiotensinogen-induced apoptosis at a concentration of 50 μg/ml. With RT-PCR, both cell types expressed the ANG II-receptor subtypes 1 and 2 and angiotensin-converting enzyme (ACE). The nonthiol ACE inhibitor lisinopril blocked apoptosis induced by angiotensinogen, but not apoptosis induced by purified ANG II. These data demonstrate the presence of a functional ANG II-dependent pathway for apoptosis in human and rat AECs and suggest a role for the ANG II receptor and ACE in the induction of AEC apoptosis in vivo.

Fas-induced apoptosis of alveolar epithelial cells requires ANG II generation and receptor interaction

1999 ◽  
Vol 277 (6) ◽  
pp. L1245-L1250 ◽  
Author(s):  
Rongqi Wang ◽  
Alex Zagariya ◽  
Edmund Ang ◽  
Olivia Ibarra-Sunga ◽  
Bruce D. Uhal
Keyword(s):  
Epithelial Cells ◽  
Ace Inhibitor ◽  
A549 Cells ◽  
Renin Angiotensin System ◽  
Alveolar Epithelial Cells ◽  
Ang Ii ◽  
Angiotensin System ◽  
Alveolar Epithelial ◽  
Induced Apoptosis ◽  
Dose Dependent

Recent works from this laboratory demonstrated potent inhibition of Fas-induced apoptosis in alveolar epithelial cells (AECs) by the angiotensin-converting enzyme (ACE) inhibitor captopril [B. D. Uhal, C. Gidea, R. Bargout, A. Bifero, O. Ibarra-Sunga, M. Papp, K. Flynn, and G. Filippatos. Am. J. Physiol. 275 ( Lung Cell. Mol. Physiol. 19): L1013–L1017, 1998] and induction of dose-dependent apoptosis in AECs by purified angiotensin (ANG) II [R. Wang, A. Zagariya, O. Ibarra-Sunga, C. Gidea, E. Ang, S. Deshmukh, G. Chaudhary, J. Baraboutis, G. Filippatos and B. D. Uhal. Am. J. Physiol. 276 ( Lung Cell. Mol. Physiol. 20): L885–L889, 1999]. These findings led us to hypothesize that the synthesis and binding of ANG II to its receptor might be involved in the induction of AEC apoptosis by Fas. Apoptosis was induced in the AEC-derived human lung carcinoma cell line A549 or in primary AECs isolated from adult rats with receptor-activating anti-Fas antibodies or purified recombinant Fas ligand, respectively. Apoptosis in response to either Fas activator was inhibited in a dose-dependent manner by the nonthiol ACE inhibitor lisinopril or the nonselective ANG II receptor antagonist saralasin, with maximal inhibitions of 82 and 93% at doses of 0.5 and 5 μg/ml, respectively. In both cell types, activation of Fas caused a significant increase in the abundance of mRNA for angiotensinogen (ANGEN) that was unaffected by saralasin. Transfection with antisense oligonucleotides against ANGEN mRNA inhibited the subsequent induction of Fas-stimulated apoptosis by 70% in A549 cells and 87% in primary AECs (both P < 0.01). Activation of Fas increased the concentration of ANG II in the serum-free extracellular medium 3-fold in primary AECs and 10-fold in A549 cells. Apoptosis in response to either Fas activator was completely abrogated by neutralizing antibodies specific for ANG II ( P < 0.01), but isotype-matched nonimmune immunoglobulins had no significant effect. These data indicate that the induction of AEC apoptosis by Fas requires a functional renin-angiotensin system in the target cell. They also suggest that therapeutic control of AEC apoptosis is feasible through pharmacological manipulation of the local renin-angiotensin system.

Angiotensin receptor subtype AT1 mediates alveolar epithelial cell apoptosis in response to ANG II

2002 ◽  
Vol 282 (4) ◽  
pp. L713-L718 ◽  
Author(s):  
Michael Papp ◽  
Xiaopeng Li ◽  
Jiaju Zhuang ◽  
Rongqi Wang ◽  
Bruce D. Uhal
Keyword(s):  
Alveolar Epithelial Cell ◽  
Tyrosine Phosphatase ◽  
Cell Types ◽  
Alveolar Epithelial Cells ◽  
Receptor Subtype ◽  
Receptor Subtypes ◽  
Dependent Manner ◽  
Ang Ii ◽  
Alveolar Epithelial ◽  
Induced Apoptosis

Previous work from this laboratory demonstrated induction of apoptosis in lung alveolar epithelial cells (AEC) by purified angiotensin II (ANG II) and expression of mRNAs for both ANG II receptor subtypes AT1 and AT2(Wang R, Zagariya A, Ibarra-Sunga O, Gidea C, Ang E, Deshmukh S, Chaudhary G, Baraboutis J, Filippatos G, and Uhal BD. Am J Physiol Lung Cell Mol Physiol 276: L885–L889, 1999.). The present study was designed to determine the ANG II receptor subtype mediating AEC apoptosis in response to ANG II. Apoptosis was induced with purified ANG II applied to the human lung AEC-derived carcinoma cell line A549 or to primary AEC isolated from Wistar rats. In both cell types, the AT1-selective receptor antagonists L-158809 or losartan inhibited ANG II-induced apoptosis by 90% at concentrations of 10−8 M and 10−7 M, respectively. The inhibition was concentration dependent with IC50 of 10−12 M and 10−11 M on the primary rat AEC. In contrast, the AT2-selective antagonists PD-123319 or PD-126055 could not block ANG II-induced apoptosis in either cell type. In primary rat AEC, apoptosis in response to ANG II was blunted in a dose-dependent manner by the protein kinase C inhibitor chelerythrine but not by the tyrosine phosphatase inhibitor sodium orthovanadate. Together, these data indicate that AEC apoptosis in response to ANG II is mediated by receptor subtype AT1, despite the expression of mRNAs for both AT1 and AT2.

scholarly journals Human lung myofibroblast-derived inducers of alveolar epithelial apoptosis identified as angiotensin peptides

1999 ◽  
Vol 277 (6) ◽  
pp. L1158-L1164 ◽  
Author(s):  
Rongi Wang ◽  
Carlos Ramos ◽  
Iravati Joshi ◽  
Alex Zagariya ◽  
Annie Pardo ◽  
...  
Keyword(s):  
Conditioned Medium ◽  
Human Lung ◽  
Smooth Muscle Actin ◽  
Alveolar Epithelial Cells ◽  
Lung Fibroblasts ◽  
Normal Fibroblast ◽  
Ang Ii ◽  
Alveolar Epithelial ◽  
Apoptotic Activity

Earlier work from this laboratory found that fibroblasts isolated from fibrotic human lung [human interstitial pulmonary fibrosis (HIPF)] secrete a soluble inducer(s) of apoptosis in alveolar epithelial cells (AECs) in vitro [B. D. Uhal, I. Joshi, A. True, S. Mundle, A. Raza, A. Pardo, and M. Selman. Am. J. Physiol. 269 ( Lung Cell. Mol. Physiol. 13): L819–L828, 1995]. The cultured human fibroblast strains most active in producing the apoptotic activity contained high numbers of stellate cells expressing α-smooth muscle actin, a myofibroblast marker. The apoptotic activity eluted from gel-filtration columns only in fractions corresponding to proteins. Western blotting of the protein fraction identified immunoreactive angiotensinogen (ANGEN), and two-step RT-PCR revealed expression of ANGEN by HIPF fibroblasts but not by normal human lung fibroblasts. Specific ELISA detected angiotensin II (ANG II) at concentrations sixfold higher in HIPF-conditioned medium than in normal fibroblast-conditioned medium. Pretreatment of the concentrated medium with purified renin plus purified angiotensin-converting enzyme (ACE) further increased the ELISA-detectable ANG II eightfold. Apoptosis of AECs in response to HIPF-conditioned medium was completely abrogated by the ANG II receptor antagonist saralasin (50 μg/ml) or anti-ANG II antibodies. These results identify the protein inducers of AEC apoptosis produced by HIPF fibroblasts as ANGEN and its derivative ANG II. They also suggest a mechanism for AEC death adjacent to HIPF myofibroblasts [B. D. Uhal,, I. Joshi, C. Ramos, A. Pardo, and M. Selman. Am. J. Physiol. 275 ( Lung Cell. Mol. Physiol. 19): L1192–L1199, 1998].

Cl-channel activation is necessary for stimulation of Na transport in adult alveolar epithelial cells

2000 ◽  
Vol 278 (2) ◽  
pp. L239-L244 ◽  
Author(s):  
Scott M. O'Grady ◽  
Xinpo Jiang ◽  
David H. Ingbar
Keyword(s):  
Epithelial Cells ◽  
Adrenergic Receptor ◽  
Apical Membrane ◽  
Receptor Activation ◽  
Alveolar Epithelial Cells ◽  
Na Channels ◽  
Channel Activation ◽  
Alveolar Epithelial ◽  
Cl Channel ◽  
Stimulation Of

In this review, we discuss evidence that supports the hypothesis that adrenergic stimulation of transepithelial Na absorption across the alveolar epithelium occurs indirectly by activation of apical Cl channels, resulting in hyperpolarization and an increased driving force for Na uptake through amiloride-sensitive Na channels. This hypothesis differs from the prevailing idea that adrenergic-receptor activation increases the open probability of Na channels, leading to an increase in apical membrane Na permeability and an increase in Na and fluid uptake from the alveolar space. We review results from cultured alveolar epithelial cell monolayer experiments that show increases in apical membrane Cl conductance in the absence of any change in Na conductance after stimulation by selective β-adrenergic-receptor agonists. We also discuss possible reasons for differences in Na-channel regulation in cells grown in monolayer culture compared with that in dissociated alveolar epithelial cells. Finally, we describe some preliminary in vivo data that suggest a role for Cl-channel activation in the process of amiloride-sensitive alveolar fluid absorption.

Hyperoxia-induced apoptosis and Fas/FasL expression in lung epithelial cells

2005 ◽  
Vol 289 (4) ◽  
pp. L647-L659 ◽  
Author(s):  
Monique E. De Paepe ◽  
Quanfu Mao ◽  
Yvonne Chao ◽  
Jessica L. Powell ◽  
Lewis P. Rubin ◽  
...  
Keyword(s):  
Cell Death ◽  
Epithelial Cells ◽  
Protein Expression ◽  
Cell Apoptosis ◽  
Receptor Activation ◽  
Type Ii ◽  
Fasl Expression ◽  
Alveolar Epithelial ◽  
Type Ii Cell ◽  
Induced Apoptosis

Alveolar epithelial apoptosis is an important feature of hyperoxia-induced lung injury in vivo and has been described in the early stages of bronchopulmonary dysplasia (chronic lung disease of preterm newborn). Molecular regulation of hyperoxia-induced alveolar epithelial cell death remains incompletely understood. In view of functional involvement of Fas/FasL system in physiological postcanalicular type II cell apoptosis, we speculated this system may also be a critical regulator of hyperoxia-induced apoptosis. The aim of this study was to investigate the effects of hyperoxia on apoptosis and apoptotic gene expression in alveolar epithelial cells. Apoptosis was studied by TUNEL, electron microscopy, DNA size analysis, and caspase assays. Fas/FasL expression was determined by Western blot analysis and RPA. We determined that in MLE-12 cells exposed to hyperoxia, caspase-mediated apoptosis was the first morphologically and biochemically recognizable mode of cell death, followed by necrosis of residual adherent cells. The apoptotic stage was associated with a threefold upregulation of Fas mRNA and protein expression and increased susceptibility to direct Fas receptor activation, concomitant with a threefold increase of FasL protein levels. Fas gene silencing by siRNAs significantly reduced hyperoxia-induced apoptosis. In murine fetal type II cells, hyperoxia similarly induced markedly increased Fas/FasL protein expression, confirming validity of results obtained in transformed MLE-12 cells. Our findings implicate the Fas/FasL system as an important regulator of hyperoxia-induced type II cell apoptosis. Elucidation of regulation of hyperoxia-induced lung apoptosis may lead to alternative therapeutic strategies for perinatal or adult pulmonary diseases characterized by dysregulated type II cell apoptosis.

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