1
|
Xu W, Ma X, Wang Q, Ye J, Wang N, Ye Z, Chen T. GCN5L1 regulates pulmonary surfactant production by modulating lamellar body biogenesis and trafficking in mouse alveolar epithelial cells. Cell Mol Biol Lett 2023; 28:90. [PMID: 37936104 PMCID: PMC10631113 DOI: 10.1186/s11658-023-00506-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Accepted: 10/25/2023] [Indexed: 11/09/2023] Open
Abstract
BACKGROUND The pulmonary surfactant that lines the air-liquid surface within alveoli is a protein-lipid mixture essential for gas exchange. Surfactant lipids and proteins are synthesized and stored in the lamellar body (LB) before being secreted from alveolar type II (AT2) cells. The molecular and cellular mechanisms that regulate these processes are incompletely understood. We previously identified an essential role of general control of amino acid synthesis 5 like 1 (GCN5L1) and the biogenesis of lysosome-related organelle complex 1 subunit 1 (BLOS1) in surfactant system development in zebrafish. Here, we explored the role of GCN5L1 in pulmonary surfactant regulation. METHOD GCN5L1 knockout cell lines were generated with the CRISPR/Cas9 system. Cell viability was analyzed by MTT assay. Released surfactant proteins were measured by ELISA. Released surfactant lipids were measured based on coupled enzymatic reactions. Gene overexpression was mediated through lentivirus. The RNA levels were detected through RNA-sequencing (RNA-seq) and quantitative reverse transcription (qRT)- polymerase chain reaction (PCR). The protein levels were detected through western blotting. The cellular localization was analyzed by immunofluorescence. Morphology of the lamellar body was analyzed through transmission electron microscopy (TEM), Lysotracker staining, and BODIPY phosphatidylcholine labeling. RESULTS Knocking out GCN5L1 in MLE-12 significantly decreased the release of surfactant proteins and lipids. We detected the downregulation of some surfactant-related genes and misregulation of the ROS-Erk-Foxo1-Cebpα axis in mutant cells. Modulating the activity of the axis or reconstructing the mitochondrial expression of GCN5L1 could partially restore the expression of these surfactant-related genes. We further showed that MLE-12 cells contained many LB-like organelles that were lipid enriched and positive for multiple LB markers. These organelles were smaller in size and accumulated in the absence of GCN5L1, indicating both biogenesis and trafficking defects. Accumulated endogenous surfactant protein (SP)-B or exogenously expressed SP-B/SP-C in adenosine triphosphate-binding cassette transporterA3 (ABCA3)-positive organelles was detected in mutant cells. GCN5L1 localized to the mitochondria and LBs. Reconstruction of mitochondrial GCN5L1 expression rescued the organelle morphology but failed to restore the trafficking defect and surfactant release, indicating specific roles associated with different subcellular localizations. CONCLUSIONS In summary, our study identified GCN5L1 as a new regulator of pulmonary surfactant that plays a role in the biogenesis and positioning/trafficking of surfactant-containing LBs.
Collapse
Affiliation(s)
- Wenqin Xu
- Central Laboratory, Yijishan Hospital of Wannan Medical College, Wuhu, China
- Anhui Province Key Laboratory of Non-Coding RNA Basic and Clinical Transformation, Wannan Medical College, Wuhu, China
- Clinical Research Center for Critical Respiratory Medicine of Anhui Province, Wannan Medical College, Wuhu, China
| | - Xiaocui Ma
- Henan Clinical Research Center of Childhood Diseases, Children's Hospital Affiliated to Zhengzhou University, Zhengzhou, China
| | - Qing Wang
- Central Laboratory, Yijishan Hospital of Wannan Medical College, Wuhu, China
- Anhui Province Key Laboratory of Non-Coding RNA Basic and Clinical Transformation, Wannan Medical College, Wuhu, China
- Clinical Research Center for Critical Respiratory Medicine of Anhui Province, Wannan Medical College, Wuhu, China
| | - Jingjing Ye
- Central Laboratory, Yijishan Hospital of Wannan Medical College, Wuhu, China
- Anhui Province Key Laboratory of Non-Coding RNA Basic and Clinical Transformation, Wannan Medical College, Wuhu, China
- Clinical Research Center for Critical Respiratory Medicine of Anhui Province, Wannan Medical College, Wuhu, China
| | - Nengqian Wang
- Department of Pediatrics, Yijishan Hospital of Wannan Medical College, Wuhu, China
| | - Zhenzhen Ye
- Department of Pediatrics, Yijishan Hospital of Wannan Medical College, Wuhu, China
| | - Tianbing Chen
- Central Laboratory, Yijishan Hospital of Wannan Medical College, Wuhu, China.
- Anhui Province Key Laboratory of Non-Coding RNA Basic and Clinical Transformation, Wannan Medical College, Wuhu, China.
- Clinical Research Center for Critical Respiratory Medicine of Anhui Province, Wannan Medical College, Wuhu, China.
| |
Collapse
|
2
|
Adeniyi JN, Nlooto M, Ngcobo M, Moodley R, Gomo E. Anticancer effects of herbal medicine Emelia-M, Mshikazi and Delosma H against human leukaemia cells. Afr Health Sci 2023; 23:305-329. [PMID: 38223600 PMCID: PMC10782316 DOI: 10.4314/ahs.v23i2.35] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2024] Open
Abstract
Background Leukaemia is one of the three major types of blood cancers that lead to the overproduction of abnormal white blood cells. Emelia M (EMB), Mshikazi and Delosma H are herbal medicines that are being used by traditional healers in KwaZulu-Natal, South Africa to treat leukaemia and other diseases. Objectives To gain insight into the safety (non-toxic effect), anti-cancer activity, mechanisms of action and phytochemical profiles of traditional herbal medicines (Emelia M (EMB), Mshikazi and Delosma H) in South Africa. Methods The viability of human peripheral blood mononuclear cells (PBMCs), monocytic (THP-1) and T-lymphocyte (Jurkat) cell lines exposed to varying concentrations of aqueous extracts of the three herbal medicines were assessed using adenosine triphosphate (ATP) assay. Results All three extracts showed a dose-dependent effect on the viability of PBMCs. Cell viability decreased with increasing concentrations of extracts when compared with the untreated cells at 24 and 48 hours. The inhibitory activities (IC50) of the extract were found in the order of Mshikazi > EMB, > Delosma H. All the extracts induced apoptosis with minimal necrosis. Many bioactive compounds that have been previously reported to have anticancer effects were identified in the extracts. Conclusion Mshikazi extract significantly inhibited the growth of THP-1 and Jurkat cells and induced cell death through apoptosis than the other two extracts.
Collapse
Affiliation(s)
- Joy Nkechinyere Adeniyi
- Traditional Medicine Laboratory, School of Nursing and Public Health, College of Health Sciences, University of KwaZulu-Natal
| | - Manimbulu Nlooto
- Department of Pharmacy, School of Health care Sciences, University of Limpopo
| | - Mlungisi Ngcobo
- Traditional Medicine Laboratory, School of Nursing and Public Health, College of Health Sciences, University of KwaZulu-Natal
| | - Roshila Moodley
- Department of Chemistry, School of Physics and Chemistry, University of KwaZulu-Natal
| | - Exnevia Gomo
- Traditional Medicine Laboratory, School of Nursing and Public Health, College of Health Sciences, University of KwaZulu-Natal
| |
Collapse
|
3
|
Xu C, Xu J, Tang HW, Ericsson M, Weng JH, DiRusso J, Hu Y, Ma W, Asara JM, Perrimon N. A phosphate-sensing organelle regulates phosphate and tissue homeostasis. Nature 2023; 617:798-806. [PMID: 37138087 PMCID: PMC10443203 DOI: 10.1038/s41586-023-06039-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Accepted: 03/31/2023] [Indexed: 05/05/2023]
Abstract
Inorganic phosphate (Pi) is one of the essential molecules for life. However, little is known about intracellular Pi metabolism and signalling in animal tissues1. Following the observation that chronic Pi starvation causes hyperproliferation in the digestive epithelium of Drosophila melanogaster, we determined that Pi starvation triggers the downregulation of the Pi transporter PXo. In line with Pi starvation, PXo deficiency caused midgut hyperproliferation. Interestingly, immunostaining and ultrastructural analyses showed that PXo specifically marks non-canonical multilamellar organelles (PXo bodies). Further, by Pi imaging with a Förster resonance energy transfer (FRET)-based Pi sensor2, we found that PXo restricts cytosolic Pi levels. PXo bodies require PXo for biogenesis and undergo degradation following Pi starvation. Proteomic and lipidomic characterization of PXo bodies unveiled their distinct feature as an intracellular Pi reserve. Therefore, Pi starvation triggers PXo downregulation and PXo body degradation as a compensatory mechanism to increase cytosolic Pi. Finally, we identified connector of kinase to AP-1 (Cka), a component of the STRIPAK complex and JNK signalling3, as the mediator of PXo knockdown- or Pi starvation-induced hyperproliferation. Altogether, our study uncovers PXo bodies as a critical regulator of cytosolic Pi levels and identifies a Pi-dependent PXo-Cka-JNK signalling cascade controlling tissue homeostasis.
Collapse
Affiliation(s)
- Chiwei Xu
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, MA, USA.
- Robin Chemers Neustein Laboratory of Mammalian Development and Cell Biology, The Rockefeller University, New York, NY, USA.
| | - Jun Xu
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
- CAS Key Laboratory of Insect Developmental and Evolutionary Biology, CAS Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Hong-Wen Tang
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
- Program in Cancer and Stem Cell Biology, Duke-NUS Medical School, Singapore, Singapore
| | - Maria Ericsson
- Department of Cell Biology, Electron Microscopy Facility, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
| | - Jui-Hsia Weng
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | - Jonathan DiRusso
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
| | - Yanhui Hu
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
| | - Wenzhe Ma
- Department of Systems Biology, Harvard Medical School, Boston, MA, USA
| | - John M Asara
- Department of Medicine, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
- Department of Signal Transduction, Beth Israel Deaconess Medical Center, Boston, MA, USA
| | - Norbert Perrimon
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, MA, USA.
- Howard Hughes Medical Institute, Harvard Medical School, Boston, MA, USA.
| |
Collapse
|
4
|
Dietl P, Frick M. Channels and Transporters of the Pulmonary Lamellar Body in Health and Disease. Cells 2021; 11:45. [PMID: 35011607 PMCID: PMC8750383 DOI: 10.3390/cells11010045] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Revised: 12/20/2021] [Accepted: 12/22/2021] [Indexed: 02/06/2023] Open
Abstract
The lamellar body (LB) of the alveolar type II (ATII) cell is a lysosome-related organelle (LRO) that contains surfactant, a complex mix of mainly lipids and specific surfactant proteins. The major function of surfactant in the lung is the reduction of surface tension and stabilization of alveoli during respiration. Its lack or deficiency may cause various forms of respiratory distress syndrome (RDS). Surfactant is also part of the innate immune system in the lung, defending the organism against air-borne pathogens. The limiting (organelle) membrane that encloses the LB contains various transporters that are in part responsible for translocating lipids and other organic material into the LB. On the other hand, this membrane contains ion transporters and channels that maintain a specific internal ion composition including the acidic pH of about 5. Furthermore, P2X4 receptors, ligand gated ion channels of the danger signal ATP, are expressed in the limiting LB membrane. They play a role in boosting surfactant secretion and fluid clearance. In this review, we discuss the functions of these transporting pathways of the LB, including possible roles in disease and as therapeutic targets, including viral infections such as SARS-CoV-2.
Collapse
Affiliation(s)
- Paul Dietl
- Institute of General Physiology, Ulm University, Albert-Einstein-Allee 11, 89081 Ulm, Germany
| | - Manfred Frick
- Institute of General Physiology, Ulm University, Albert-Einstein-Allee 11, 89081 Ulm, Germany
| |
Collapse
|
5
|
Martínez-Calle M, Alonso A, Pérez-Gil J, Olmeda B. Native supramolecular protein complexes in pulmonary surfactant: Evidences for SP-A/SP-B interactions. J Proteomics 2019; 207:103466. [DOI: 10.1016/j.jprot.2019.103466] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Revised: 07/08/2019] [Accepted: 07/22/2019] [Indexed: 12/21/2022]
|
6
|
Kook S, Qi A, Wang P, Meng S, Gulleman P, Young LR, Guttentag SH. Gene-edited MLE-15 Cells as a Model for the Hermansky-Pudlak Syndromes. Am J Respir Cell Mol Biol 2019; 58:566-574. [PMID: 29190429 DOI: 10.1165/rcmb.2017-0324ma] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Defining the mechanisms of cellular pathogenesis in rare lung diseases such as Hermansky-Pudlak syndrome (HPS) is often complicated by loss of the differentiated phenotype of cultured primary alveolar type 2 (AT2) cells, as well as by a lack of durable cell lines that are faithful to both AT2-cell and rare disease phenotypes. We used CRISPR/Cas9 gene editing to generate a series of HPS-specific mutations in the MLE-15 cell line. The resulting MLE-15/HPS cell lines exhibit preservation of AT2 cellular functions, including formation of lamellar body-like organelles, complete processing of surfactant protein B, and known features of HPS specific to each trafficking complex, including loss of protein targeting to lamellar bodies. MLE-15/HPS1 and MLE-15/HPS2 (with a mutation in Ap3β1) express increased macrophage chemotactic protein-1, a well-described mediator of alveolitis in patients with HPS and in mouse models. We show that MLE-15/HPS9 and pallid AT2 cells (with a mutation in Bloc1s6) also express increased macrophage chemotactic protein-1, suggesting that mice and humans with BLOC-1 mutations may also be susceptible to alveolitis. In addition to providing a flexible platform to examine the role of HPS-specific mutations in trafficking AT2 cells, MLE-15/HPS cell lines provide a durable resource for high-throughput screening and studies of cellular pathophysiology that are likely to accelerate progress toward developing novel therapies for this rare lung disease.
Collapse
Affiliation(s)
| | - Aidong Qi
- 2 Division of Pediatric Pulmonary Medicine, Department of Pediatrics, Vanderbilt University School of Medicine, Nashville, Tennessee
| | | | | | - Peter Gulleman
- 2 Division of Pediatric Pulmonary Medicine, Department of Pediatrics, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Lisa R Young
- 2 Division of Pediatric Pulmonary Medicine, Department of Pediatrics, Vanderbilt University School of Medicine, Nashville, Tennessee
| | | |
Collapse
|
7
|
Unuma K, Aki T, Noritake K, Funakoshi T, Uemura K. A CO-releasing molecule prevents annexin A2 down-regulation and associated disorders in LPS-administered rat lung. Biochem Biophys Res Commun 2017; 487:748-754. [DOI: 10.1016/j.bbrc.2017.04.131] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2017] [Accepted: 04/23/2017] [Indexed: 01/11/2023]
|
8
|
Cerrada A, Haller T, Cruz A, Pérez-Gil J. Pneumocytes Assemble Lung Surfactant as Highly Packed/Dehydrated States with Optimal Surface Activity. Biophys J 2016; 109:2295-306. [PMID: 26636941 DOI: 10.1016/j.bpj.2015.10.022] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2015] [Revised: 10/08/2015] [Accepted: 10/13/2015] [Indexed: 01/22/2023] Open
Abstract
Pulmonary surfactant (PS) is an essential complex of lipids and specific proteins synthesized in alveolar type II pneumocytes, where it is assembled and stored intracellularly as multilayered organelles known as lamellar bodies (LBs). Once secreted upon physiological stimulation, LBs maintain a densely packed structure in the form of lamellar body-like particles (LBPs), which are efficiently transferred into the alveolar air-water interface, lowering surface tension to avoid lung collapse at end-expiration. In this work, the structural organization of membranes in LBs and LBPs freshly secreted by primary cultures of rat ATII cells has been compared with that of native lung surfactant membranes isolated from porcine bronchoalveolar lavage. PS assembles in LBs as crystalline-like highly ordered structures, with a highly packed and dehydrated state, which is maintained at supraphysiological temperatures. This relatively ordered/packed state is retained in secreted LBPs. The micro- and nanostructural examination of LBPs suggests the existence of high levels of structural complexity in comparison with the material purified from lavages, which may contain partially inactivated or spent structures. Additionally, freshly secreted surfactant LBPs exhibit superior activity when generating interfacial films and a higher intrinsic resistance to inactivating agents, such as serum proteins or meconium. We propose that LBs are assembled as an energy-activated structure competent to form very efficient interfacial films, and that the organization of lipids and proteins and the properties displayed by the films formed by LBPs are likely similar to those established at the alveolar interface and represent the actual functional structure of surfactant as it sustains respiration.
Collapse
Affiliation(s)
- Alejandro Cerrada
- Department of Biochemistry, Faculty of Biology, and Hospital 12 Octubre Research Institute, Universidad Complutense, Madrid, Spain
| | - Thomas Haller
- Department of Physiology and Medical Physics, Medical University of Innsbruck, Innsbruck, Austria
| | - Antonio Cruz
- Department of Biochemistry, Faculty of Biology, and Hospital 12 Octubre Research Institute, Universidad Complutense, Madrid, Spain
| | - Jesús Pérez-Gil
- Department of Biochemistry, Faculty of Biology, and Hospital 12 Octubre Research Institute, Universidad Complutense, Madrid, Spain.
| |
Collapse
|
9
|
Thurm T, Kaltenborn E, Kern S, Griese M, Zarbock R. SFTPC mutations cause SP-C degradation and aggregate formation without increasing ER stress. Eur J Clin Invest 2013; 43:791-800. [PMID: 23701443 DOI: 10.1111/eci.12107] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/25/2012] [Accepted: 04/21/2013] [Indexed: 01/11/2023]
Abstract
BACKGROUND Mutations in the gene encoding surfactant protein C (SP-C) cause familial and sporadic interstitial lung disease (ILD), which is associated with considerable morbidity and mortality. Unfortunately, effective therapeutic options are still lacking due to a very limited understanding of pathomechanisms. Knowledge of mutant SP-C proprotein (proSP-C) trafficking, processing, intracellular degradation and aggregation is a crucial prerequisite for the development of specific therapies to correct aberrant trafficking and processing of proSP-C and to hinder accumulation of cytotoxic aggregates. MATERIALS AND METHODS To identify possible starting points for therapeutic intervention, we stably transfected A549 alveolar epithelial cells with several proSP-C mutations previously found in patients suffering from ILD. Effects of mutant proSP-C were assessed by Western blotting, immunofluorescence and Congo red staining. RESULTS A group of mutations (p.I73T, p.L110R, p.A116D and p.L188Q) resulted in aberrant proSP-C products, which were at least partially trafficked to lamellar bodies. Another group of mutations (p.P30L and p.P115L) was arrested in the endoplasmic reticulum (ER). Except for p.I73T, all mutations led to accumulation of intracellular Congo red-positive aggregates. Enhanced ER stress was detectable in none of these stably transfected cells. CONCLUSIONS Different SP-C mutations have unique consequences for alveolar epithelial cell biology. As these cannot be predicted based upon the localization of the mutation, our data emphasize the importance of studying individual mutations in detail in order to develop mutation-specific therapies.
Collapse
Affiliation(s)
- Tobias Thurm
- Dr. von Hauner Children's Hospital, Ludwig-Maximilians-University, Munich, Germany
| | | | | | | | | |
Collapse
|
10
|
Liu Y, Wei J, Chang M, Liu Z, Li D, Hu S, Hu L. Proteomic analysis of endothelial progenitor cells exposed to oxidative stress. Int J Mol Med 2013; 32:607-14. [PMID: 23778534 DOI: 10.3892/ijmm.2013.1419] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2013] [Accepted: 05/30/2013] [Indexed: 11/05/2022] Open
Abstract
Endothelial progenitor cells (EPCs) repair vascular damage and participate in neovascularization. Accumulating evidence has demonstrated that EPCs have therapeutic potential in reactive oxygen species (ROS)-mediated vascular diseases. In this study, to investigate the effects of oxidative stress on EPCs, EPCs were treated with H2O2 at different final concentrations for 3 h. MTT assay, scratch-wound assay and Matrigel invasion assay revealed that cell proliferation, migration and tubule formation and function, respectively, were impaired under H2O2 stress in a concentration-dependent manner. To determine protein response to H2O2 stress, two-dimensional differential in-gel electrophoresis (2D-DIGE) combined with matrix-assisted laser desorption-ionization time-of-flight (MALDI-TOF/TOF) mass spectrometry were performed. The results revealed that triosephosphate isomerase and ADP-sugar pyrophosphatase were downregulated, while peroxiredoxin-2, thioredoxin-dependent peroxide reductase, mitochondrial (Prx‑3), peroxiredoxin-6, EGF-containing fibulin-like extracellular matrix protein 1, vimentin and Rab GDP dissociation inhibitor α were upregulated in the H2O2-treated EPCs. To further confirm the results from mass spectrometry, the expression pattern of Prx-3 in response to H2O2 stress was examined by western blot analysis. The data presented in this study provide novel insight into the defensive mechanisms of EPCs and the pathways of oxidative damage in an oxidative environment.
Collapse
Affiliation(s)
- Ying Liu
- Department of Neurology, the Second Affiliated Hospital of Dalian Medical University, Dalian, Liaoning 116023, P.R. China
| | | | | | | | | | | | | |
Collapse
|
11
|
Konsavage WM, Umstead TM, Wu Y, Phelps DS, Shenberger JS. Hyperoxia-induced alterations in the pulmonary proteome of juvenile rats. Exp Lung Res 2013; 39:107-17. [DOI: 10.3109/01902148.2013.763871] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
|
12
|
Dietl P, Haller T, Frick M. Spatio-temporal aspects, pathways and actions of Ca(2+) in surfactant secreting pulmonary alveolar type II pneumocytes. Cell Calcium 2012; 52:296-302. [PMID: 22591642 DOI: 10.1016/j.ceca.2012.04.010] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2012] [Revised: 04/11/2012] [Accepted: 04/18/2012] [Indexed: 01/16/2023]
Abstract
The type II cell of the pulmonary alveolus is a polarized epithelial cell that secretes surfactant into the alveolar space by regulated exocytosis of lamellar bodies (LBs). This process consists of multiple sequential steps and is correlated to elevations of the cytoplasmic Ca(2+) concentration ([Ca(2+)](c)) required for extended periods of secretory activity. Both chemical (purinergic) and mechanical (cell stretch or exposure to an air-liquid interface) stimuli give rise to complex Ca(2+) signals (such as Ca(2+) peaks, spikes and plateaus) that differ in shape, origin and spatio-temporal behavior. This review summarizes current knowledge about Ca(2+) channels, including vesicular P2X4 purinoceptors, in type II cells and associated signaling cascades within the alveolar microenvironment, and relates stimulus-dependent activation of these pathways with distinct stages of surfactant secretion, including pre- and postfusion stages of LB exocytosis.
Collapse
Affiliation(s)
- Paul Dietl
- Institute of General Physiology, University of Ulm, Albert-Einstein-Allee 11, 89081 Ulm, Germany.
| | | | | |
Collapse
|
13
|
Roszell BR, Tao JQ, Yu KJ, Huang S, Bates SR. Characterization of the Niemann-Pick C pathway in alveolar type II cells and lamellar bodies of the lung. Am J Physiol Lung Cell Mol Physiol 2012; 302:L919-32. [PMID: 22367786 DOI: 10.1152/ajplung.00383.2011] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The Niemann-Pick C (NPC) pathway plays an essential role in the intracellular trafficking of cholesterol by facilitating the release of lipoprotein-derived sterol from the lumen of lysosomes. Regulation of cellular cholesterol homeostasis is of particular importance to lung alveolar type II cells because of the need for production of surfactant with an appropriate lipid composition. We performed microscopic and biochemical analysis of NPC proteins in isolated rat type II pneumocytes. NPC1 and NPC2 proteins were present in the lung, isolated type II cells in culture, and alveolar macrophages. The glycosylated and nonglycosylated forms of NPC1 were prominent in the lung and the lamellar body organelles. Immunocytochemical analysis of isolated type II pneumocytes showed localization of NPC1 to the limiting membrane of lamellar bodies. NPC2 and lysosomal acid lipase were found within these organelles, as confirmed by z-stack analysis of confocal images. All three proteins also were identified in small, lysosome-like vesicles. In the presence of serum, pharmacological inhibition of the NPC pathway with compound U18666A resulted in doubling of the cholesterol content of the type II cells. Filipin staining revealed a striking accumulation of cholesterol within lamellar bodies. Thus the NPC pathway functions to control cholesterol accumulation in lamellar bodies of type II pneumocytes and, thereby, may play a role in the regulation of surfactant cholesterol content.
Collapse
Affiliation(s)
- Blair R Roszell
- Institute for Environmental Medicine, Univ. of Pennsylvania, Philadelphia, PA 19104-6068, USA
| | | | | | | | | |
Collapse
|
14
|
Bredberg A, Gobom J, Almstrand AC, Larsson P, Blennow K, Olin AC, Mirgorodskaya E. Exhaled endogenous particles contain lung proteins. Clin Chem 2011; 58:431-40. [PMID: 22156667 DOI: 10.1373/clinchem.2011.169235] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
BACKGROUND We recently developed a novel, noninvasive method for sampling nonvolatile material from the distal airways. The method is based on the collection of endogenous particles in exhaled air (PEx). The aim of this study was to characterize the protein composition of PEx and to verify that the origin of PEx is respiratory tract lining fluid (RTLF). METHOD Healthy individuals exhaled into the sampling device, which collected PEx onto a silicon plate inside a 3-stage impactor. After their extraction from the plates, PEx proteins were separated by SDS-PAGE and then analyzed by LC-MS. Proteins were identified by searching the International Protein Index human database with the Mascot search engine. RESULTS Analysis of the pooled samples identified 124 proteins. A comparison of the identified PEx proteins with published bronchoalveolar lavage (BAL) proteomic data showed a high degree of overlap, with 103 (83%) of the PEx proteins having previously been detected in BAL. The relative abundances of the proteins were estimated according to the Mascot exponentially modified protein abundance index protocol and were in agreement with the expected protein composition of RTLF. No amylase was detected, indicating the absence of saliva protein contamination with our sampling technique. CONCLUSIONS Our data strongly support that PEx originate from RTLF and reflect the composition of undiluted RTLF.
Collapse
Affiliation(s)
- Anna Bredberg
- Occupational and Environmental Medicine, University of Gothenburg, Gothenburg, Sweden.
| | | | | | | | | | | | | |
Collapse
|
15
|
Côté M, Provost PR, Tremblay Y. Apolipoprotein A-I, A-II, and H mRNA and protein accumulation sites in the developing lung in late gestation. BMC Res Notes 2011; 4:235. [PMID: 21756353 PMCID: PMC3154161 DOI: 10.1186/1756-0500-4-235] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2011] [Accepted: 07/14/2011] [Indexed: 01/14/2023] Open
Abstract
BACKGROUND Expression of apolipoprotein A-I (apoA-I), A-II, and H was previously observed at 16 to 50-fold higher levels in the fetal than the adult mouse lung. Here, sites of apoA-I, A-II, and H mRNA and protein accumulation were determined in mouse fetal lungs by in situ hybridization and immunohistochemistry in late gestation. RESULTS Expression sites vary for the three genes and change for the distal epithelium before the end of the canalicular stage, thus where and when the surge of surfactant synthesis occurs. Messenger of apoH, but not those of apoA-I and A-II, was also observed in the proximal epithelium and smooth muscles surrounding arteries. In contrast to apoC-II protein, none of the three studied apolipoproteins accumulated within secretory granule-like structures. Immunohistochemistry revealed that apoA-I and apoH accumulated mainly in capillaries. Three different positive signals with the anti-apoA-II antibody were found: one transient signal in the nucleus of a portion of mesenchymal cells, a second at lower levels throughout the mesenchyme, and another in capillaries with a specific increase from gestation day 17.5/18.5. CONCLUSION Temporal and geographic co-expression of apoAI, AII, and H genes with surfactant production site suggests that the three apolipoproteins are secreted to play roles supporting the lung-specific surfactant lipid-related metabolism.
Collapse
Affiliation(s)
- Mélissa Côté
- Reproduction Axis, Perinatal and Child Health, Rm T-1-49, CHUQ Research Center, Québec City, Québec, Canada.
| | | | | |
Collapse
|
16
|
Ridsdale R, Na CL, Xu Y, Greis KD, Weaver T. Comparative proteomic analysis of lung lamellar bodies and lysosome-related organelles. PLoS One 2011; 6:e16482. [PMID: 21298062 PMCID: PMC3027677 DOI: 10.1371/journal.pone.0016482] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2010] [Accepted: 12/22/2010] [Indexed: 01/12/2023] Open
Abstract
Pulmonary surfactant is a complex mixture of lipids and proteins that is essential for postnatal function. Surfactant is synthesized in alveolar type II cells and stored as multi-bilayer membranes in a specialized secretory lysosome-related organelle (LRO), known as the lamellar body (LB), prior to secretion into the alveolar airspaces. Few LB proteins have been identified and the mechanisms regulating formation and trafficking of this organelle are poorly understood. Lamellar bodies were isolated from rat lungs, separated into limiting membrane and core populations, fractionated by SDS-PAGE and proteins identified by nanoLC-tandem mass spectrometry. In total 562 proteins were identified, significantly extending a previous study that identified 44 proteins in rat lung LB. The lung LB proteome reflects the dynamic interaction of this organelle with the biosynthetic, secretory and endocytic pathways of the type II epithelial cell. Comparison with other LRO proteomes indicated that 60% of LB proteins were detected in one or more of 8 other proteomes, confirming classification of the LB as a LRO. Remarkably the LB shared 37.8% of its proteins with the melanosome but only 9.9% with lamellar bodies from the skin. Of the 229 proteins not detected in other LRO proteomes, a subset of 34 proteins was enriched in lung relative to other tissues. Proteins with lipid-related functions comprised a significant proportion of the LB unique subset, consistent with the major function of this organelle in the organization, storage and secretion of surfactant lipid. The lung LB proteome will facilitate identification of molecular pathways involved in LB biogenesis, surfactant homeostasis and disease pathogenesis.
Collapse
Affiliation(s)
- Ross Ridsdale
- Division of Pulmonary Biology, Cincinnati Children's Hospital Medical Center, and Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, Ohio, United States of America
| | - Cheng-Lun Na
- Division of Pulmonary Biology, Cincinnati Children's Hospital Medical Center, and Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, Ohio, United States of America
| | - Yan Xu
- Division of Pulmonary Biology, Cincinnati Children's Hospital Medical Center, and Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, Ohio, United States of America
| | - Kenneth D. Greis
- Department of Cancer and Cell Biology, University of Cincinnati College of Medicine, Cincinnati, Ohio, United States of America
| | - Timothy Weaver
- Division of Pulmonary Biology, Cincinnati Children's Hospital Medical Center, and Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, Ohio, United States of America
- * E-mail:
| |
Collapse
|
17
|
Perez-Gil J, Weaver TE. Pulmonary surfactant pathophysiology: current models and open questions. Physiology (Bethesda) 2010; 25:132-41. [PMID: 20551227 DOI: 10.1152/physiol.00006.2010] [Citation(s) in RCA: 173] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Pulmonary surfactant is an essential lipid-protein complex that stabilizes the respiratory units (alveoli) involved in gas exchange. Quantitative or qualitative derangements in surfactant are associated with severe respiratory pathologies. The integrated regulation of surfactant synthesis, secretion, and metabolism is critical for air breathing and, ultimately, survival. The goal of this review is to summarize our current understanding and highlight important knowledge gaps in surfactant homeostatic mechanisms.
Collapse
Affiliation(s)
- Jesús Perez-Gil
- Department Bioquímica, Faculty Biología, Universidad Complutense, Madrid, Spain.
| | | |
Collapse
|
18
|
Wemhöner A, Hackspiel I, Hobi N, Ravasio A, Haller T, Rüdiger M. Effects of perfluorocarbons on surfactant exocytosis and membrane properties in isolated alveolar type II cells. Respir Res 2010; 11:52. [PMID: 20459693 PMCID: PMC2876085 DOI: 10.1186/1465-9921-11-52] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2009] [Accepted: 05/09/2010] [Indexed: 01/05/2023] Open
Abstract
Background Perfluorocarbons (PFC) are used to improve gas exchange in diseased lungs. PFC have been shown to affect various cell types. Thus, effects on alveolar type II (ATII) cells and surfactant metabolism can be expected, data, however, are controversial. Objective The study was performed to test two hypotheses: (I) the effects of PFC on surfactant exocytosis depend on their respective vapor pressures; (II) different pathways of surfactant exocytosis are affected differently by PFC. Methods Isolated ATII cells were exposed to two PFC with different vapor pressures and spontaneous surfactant exocytosis was measured. Furthermore, surfactant exocytosis was stimulated by either ATP, PMA or Ionomycin. The effects of PFC on cell morphology, cellular viability, endocytosis, membrane permeability and fluidity were determined. Results The spontaneous exocytosis was reduced by PFC, however, the ATP and PMA stimulated exocytosis was slightly increased by PFC with high vapor pressure. In contrast, Ionomycin-induced exocytosis was decreased by PFC with low vapor pressure. Cellular uptake of FM 1-43 - a marker of membrane integrity - was increased. However, membrane fluidity, endocytosis and viability were not affected by PFC incubation. Conclusions We conclude that PFC effects can be explained by modest, unspecific interactions with the plasma membrane rather than by specific interactions with intracellular targets.
Collapse
Affiliation(s)
- Andreas Wemhöner
- University Hospital Dresden, Department for Pediatric Intensive Care and Neonatology, Technical University Dresden, Germany
| | | | | | | | | | | |
Collapse
|
19
|
Levitte S, Salesky R, King B, Coe Smith S, Depper M, Cole M, Hermann GJ. A Caenorhabditis elegans model of orotic aciduria reveals enlarged lysosome-related organelles in embryos lacking umps-1 function. FEBS J 2010; 277:1420-39. [DOI: 10.1111/j.1742-4658.2010.07573.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
|
20
|
Existence of exocytotic hemifusion intermediates with a lifetime of up to seconds in type II pneumocytes. Biochem J 2009; 424:7-14. [PMID: 19712048 DOI: 10.1042/bj20091094] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Exocytosis proceeds through prefusion stages such as hemifusion, but hemifusion is still an elusive intermediate of unknown duration. Using darkfield and fluorescence microscopy in ATII (alveolar type II) cells containing large secretory vesicles (LBs; lamellar bodies), we show that exocytotic fusion events were accompanied by a mostly biphasic SLID (scattered light intensity decrease) originating from the vesicle border. Correlation with the diffusional behaviour of fluorescence markers for either content or membrane mixing revealed that the onset of the fast second phase of SLID corresponded to fusion pore formation, which was followed by vesicle swelling. In contrast, a slow first phase of SLID preceded pore formation considerably but could still be accompanied by diffusion of farnesylated DsRed, an inner plasma membrane leaflet marker, or Nile Red. We conclude that hemifusion is an exocytotic intermediate that may last for several seconds. SLID is a new, non-invasive approach by which a prefusion phase, including hemifusion, can be continuously recorded and distinguished from fusion pore formation and postfusion vesicle swelling.
Collapse
|
21
|
Kitsiouli E, Nakos G, Lekka ME. Phospholipase A2 subclasses in acute respiratory distress syndrome. Biochim Biophys Acta Mol Basis Dis 2009; 1792:941-53. [PMID: 19577642 DOI: 10.1016/j.bbadis.2009.06.007] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2009] [Revised: 06/25/2009] [Accepted: 06/25/2009] [Indexed: 01/12/2023]
Abstract
Phospholipases A2 (PLA2) catalyse the cleavage of fatty acids esterified at the sn-2 position of glycerophospholipids. In acute lung injury-acute respiratory distress syndrome (ALI-ARDS) several distinct isoenzymes appear in lung cells and fluid. Some are capable to trigger molecular events leading to enhanced inflammation and lung damage and others have a role in lung surfactant recycling preserving lung function: Secreted forms (groups sPLA2-IIA, -V, -X) can directly hydrolyze surfactant phospholipids. Cytosolic PLA2 (cPLA2-IVA) requiring Ca2+ has a preference for arachidonate, the precursor of eicosanoids which participate in the inflammatory response in the lung. Ca(2+)-independent intracellular PLA2s (iPLA2) take part in surfactant phospholipids turnover within alveolar cells. Acidic Ca(2+)-independent PLA2 (aiPLA2), of lysosomal origin, has additionally antioxidant properties, (peroxiredoxin VI activity), and participates in the formation of dipalmitoyl-phosphatidylcholine in lung surfactant. PAF-AH degrades PAF, a potent mediator of inflammation, and oxidatively fragmented phospholipids but also leads to toxic metabolites. Therefore, the regulation of PLA2 isoforms could be a valuable approach for ARDS treatment.
Collapse
Affiliation(s)
- Eirini Kitsiouli
- Department of Biological Applications and Technologies, School of Sciences and Technologies, University of Ioannina, Greece
| | | | | |
Collapse
|