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Pioselli B, Salomone F, Mazzola G, Amidani D, Sgarbi E, Amadei F, Murgia X, Catinella S, Villetti G, De Luca D, Carnielli V, Civelli M. Pulmonary surfactant: a unique biomaterial with life-saving therapeutic applications. Curr Med Chem 2021; 29:526-590. [PMID: 34525915 DOI: 10.2174/0929867328666210825110421] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Revised: 06/26/2021] [Accepted: 06/29/2021] [Indexed: 11/22/2022]
Abstract
Pulmonary surfactant is a complex lipoprotein mixture secreted into the alveolar lumen by type 2 pneumocytes, which is composed by tens of different lipids (approximately 90% of its entire mass) and surfactant proteins (approximately 10% of the mass). It is crucially involved in maintaining lung homeostasis by reducing the values of alveolar liquid surface tension close to zero at end-expiration, thereby avoiding the alveolar collapse, and assembling a chemical and physical barrier against inhaled pathogens. A deficient amount of surfactant or its functional inactivation is directly linked to a wide range of lung pathologies, including the neonatal respiratory distress syndrome. This paper reviews the main biophysical concepts of surfactant activity and its inactivation mechanisms, and describes the past, present and future roles of surfactant replacement therapy, focusing on the exogenous surfactant preparations marketed worldwide and new formulations under development. The closing section describes the pulmonary surfactant in the context of drug delivery. Thanks to its peculiar composition, biocompatibility, and alveolar spreading capability, the surfactant may work not only as a shuttle to the branched anatomy of the lung for other drugs but also as a modulator for their release, opening to innovative therapeutic avenues for the treatment of several respiratory diseases.
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Affiliation(s)
| | | | | | | | - Elisa Sgarbi
- Preclinical R&D, Chiesi Farmaceutici, Parma. Italy
| | | | - Xabi Murgia
- Department of Biotechnology, GAIKER Technology Centre, Zamudio. Spain
| | | | | | - Daniele De Luca
- Division of Pediatrics and Neonatal Critical Care, Antoine Béclère Medical Center, APHP, South Paris University Hospitals, Paris, France; Physiopathology and Therapeutic Innovation Unit-U999, South Paris-Saclay University, Paris. France
| | - Virgilio Carnielli
- Division of Neonatology, G Salesi Women and Children's Hospital, Polytechnical University of Marche, Ancona. Italy
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Osanai K, Mizuno S, Toga H, Takahashi K. Trafficking of newly synthesized surfactant protein B to the lamellar body in alveolar type II cells. Cell Tissue Res 2020; 381:427-438. [PMID: 32556725 DOI: 10.1007/s00441-020-03232-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Accepted: 05/18/2020] [Indexed: 10/24/2022]
Abstract
Lung surfactant accumulates in the lamellar body (LB) via not only the secretory (anterograde) pathway but also the endocytic (retrograde) pathway. Our previous studies suggested that the major surfactant components, phosphatidylcholine and surfactant protein A take independent trafficking routes in alveolar type II cells. Thus, trafficking of surfactant protein B (SP-B), a major hydrophobic surfactant apoprotein, should be re-evaluated by a straightforward method. Radiolabeling of cells and subsequent cell fractionation were employed to pursue the sequential trafficking of newly synthesized SP-B in rabbit alveolar type II cells. The LB fraction was prepared by gradient ultracentrifugation. Immunoprecipitation from the culture medium, total cells, and LB fraction was carried out with anti-SP-B antibody. Newly synthesized [35S]-pro-SP-B (~ 42 kDa) was detected in the cells after 1 h. An ~ 8-kDa mature form of [35S]-SP-B was detected in the cells after 3 h and in the LB after 6 h. Mature [35S]-SP-B was predominant in the cells after 24 h, and the dominant portion was present in the LB. In contrast, only a small amount of mature [35S]-SP-B was present in the culture medium. Molecular processing of ~ 42 kDa [35S]-pro-SP-B and transport to the LB was inhibited by brefeldin A, which disassembles the Golgi apparatus. These results suggest that newly synthesized SP-B is sorted to the LB via the Golgi and stored until exocytosis. This pathway is distinct from the pathways reported for phosphatidylcholine and surfactant protein A.
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Affiliation(s)
- Kazuhiro Osanai
- Department of Life Science, Medical Research Institute, Kanazawa Medical University, 1-1 Daigaku-Uchinada, Kahoku-gun, Ishikawa, 920-0293, Japan. .,Department of Respiratory Medicine, Kanazawa Medical University, 1-1 Daigaku-Uchinada, Kahoku-gun, Ishikawa, 920-0293, Japan.
| | - Shiro Mizuno
- Department of Respiratory Medicine, Kanazawa Medical University, 1-1 Daigaku-Uchinada, Kahoku-gun, Ishikawa, 920-0293, Japan
| | - Hirohisa Toga
- Department of Respiratory Medicine, Kanazawa Medical University, 1-1 Daigaku-Uchinada, Kahoku-gun, Ishikawa, 920-0293, Japan
| | - Keiji Takahashi
- Department of Respiratory Medicine, Kanazawa Medical University, 1-1 Daigaku-Uchinada, Kahoku-gun, Ishikawa, 920-0293, Japan
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3
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Osanai K. Rab38 Mutation and the Lung Phenotype. Int J Mol Sci 2018; 19:E2203. [PMID: 30060521 PMCID: PMC6122074 DOI: 10.3390/ijms19082203] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2018] [Revised: 07/21/2018] [Accepted: 07/23/2018] [Indexed: 12/12/2022] Open
Abstract
Rab38 is highly expressed in alveolar type II cells, melanocytes, and platelets. These cells are specifically-differentiated cells and contain characteristic intracellular organelles called lysosome-related organelles, i.e., lamellar bodies in alveolar type II cells, melanosomes in melanocytes, and dense granules in platelets. There are Rab38-mutant rodents, i.e., chocolate mice and Ruby rats. While chocolate mice only show oculocutaneous albinism, Ruby rats show oculocutaneous albinism and prolonged bleeding time and, hence, are a rat model of Hermansky-Pudlak syndrome (HPS). Most patients with HPS suffer from fatal interstitial pneumonia by middle age. The lungs of both chocolate mice and Ruby rats show remarkably increased amounts of lung surfactant and conspicuously enlarged lysosome-related organelles, i.e., lamellar bodies, which are also characteristic of the lungs in human HPS. There are 16 mutant HPS-mouse strains, of which ten mutant genes have been identified to be causative in patients with HPS thus far. The gene products of eight of the ten genes constitute one of the three protein complexes, i.e., biogenesis of lysosome-related organelle complex-1, -2, -3 (BLOC-1, -2, -3). Patients with HPS of the mutant BLOC-3 genotype develop interstitial pneumonia. Recently, BLOC-3 has been elucidated to be a guanine nucleotide exchange factor for Rab38. Growing evidence suggests that Rab38 is an additional candidate gene of human HPS that displays the lung phenotype.
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Affiliation(s)
- Kazuhiro Osanai
- Department of Life Science, Medical Research Institute, Kanazawa Medical University, 1-1 Uchinada-Daigaku, Kahokugun, Ishikawa 920-0293, Japan.
- Department of Respiratory Medicine, Kanazawa Medical University, 1-1 Uchinada-Daigaku, Kahokugun, Ishikawa 920-0293, Japan.
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Osanai K, Nakase K, Sakuma T, Nishiki K, Nojiri M, Kato R, Saito M, Fujimoto Y, Mizuno S, Toga H. Exogenous gene transfer of Rab 38 small GTPase ameliorates aberrant lung surfactant homeostasis in Ruby rats. Respir Res 2017; 18:70. [PMID: 28438206 PMCID: PMC5402648 DOI: 10.1186/s12931-017-0549-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2017] [Accepted: 04/11/2017] [Indexed: 11/25/2022] Open
Abstract
Background Rab38 small GTPase regulates intracellular transport in melanocytes and alveolar type II epithelial cells. Ruby rats carrying Rab38 and other gene mutations exhibit oculocutaneous albinism, bleeding diathesis, and hence, are a rat model of human Hermansky-Pudlak syndrome (HPS). We previously showed that Long Evans Cinnamon (LEC) rats, one strain of the Ruby rats, developed aberrant lung surfactant homeostasis with remarkably enlarged lamellar bodies in alveolar type II cells. Methods A replication-deficient recombinant adenovirus expressing rat Rab38 (Ad-Rab38) was constructed. Alveolar type II cells were isolated from the LEC rats and tested for lung surfactant phosphatidylcholine secretion. The rats were also examined whether exogenous expression of Ad- Rab38 could rescue the altered lung surfactant homeostasis in the lungs. Results Isolated type II cells infected with Ad-Rab38 exhibited improved secretion patterns of [3H]phosphatidylcholine, i.e. increased basal hyposecretion and decreased agonist-induced hypersecretion. Endobronchial administration of Ad-Rab38 improved the morphology of type II cells and lamellar bodies, reducing their sizes close to those of wild-type rats. The increased amounts of phosphatidylcholine and surfactant protein B in the lamellar body fractions were decreased in the Ad-Rab38 infected lungs. Conclusions These results provide strong evidence that the aberrant lung surfactant homeostasis in the LEC rats is caused by Rab38 deficit, and suggest that endobronchial delivery of the responsive transgene could be an effective method to ameliorate the abnormal lung phenotype in the animal model of HPS.
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Affiliation(s)
- Kazuhiro Osanai
- Department of Respiratory Medicine, Kanazawa Medical University, 1-1 Uchinada-Daigaku, Kahokugun, Ishikawa, 920-0293, Japan.
| | - Keisuke Nakase
- Department of Respiratory Medicine, Kanazawa Medical University, 1-1 Uchinada-Daigaku, Kahokugun, Ishikawa, 920-0293, Japan
| | - Takashi Sakuma
- Department of Respiratory Medicine, Kanazawa Medical University, 1-1 Uchinada-Daigaku, Kahokugun, Ishikawa, 920-0293, Japan
| | - Kazuaki Nishiki
- Department of Respiratory Medicine, Kanazawa Medical University, 1-1 Uchinada-Daigaku, Kahokugun, Ishikawa, 920-0293, Japan
| | - Masafumi Nojiri
- Department of Respiratory Medicine, Kanazawa Medical University, 1-1 Uchinada-Daigaku, Kahokugun, Ishikawa, 920-0293, Japan
| | - Ryo Kato
- Department of Respiratory Medicine, Kanazawa Medical University, 1-1 Uchinada-Daigaku, Kahokugun, Ishikawa, 920-0293, Japan
| | - Masatoshi Saito
- Department of Respiratory Medicine, Kanazawa Medical University, 1-1 Uchinada-Daigaku, Kahokugun, Ishikawa, 920-0293, Japan
| | - Yuki Fujimoto
- Department of Respiratory Medicine, Kanazawa Medical University, 1-1 Uchinada-Daigaku, Kahokugun, Ishikawa, 920-0293, Japan
| | - Shiro Mizuno
- Department of Respiratory Medicine, Kanazawa Medical University, 1-1 Uchinada-Daigaku, Kahokugun, Ishikawa, 920-0293, Japan
| | - Hirohisa Toga
- Department of Respiratory Medicine, Kanazawa Medical University, 1-1 Uchinada-Daigaku, Kahokugun, Ishikawa, 920-0293, Japan
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5
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Brandsma J, Postle AD. Analysis of the regulation of surfactant phosphatidylcholine metabolism using stable isotopes. Ann Anat 2017; 211:176-183. [PMID: 28351529 DOI: 10.1016/j.aanat.2017.02.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2016] [Revised: 02/27/2017] [Accepted: 02/28/2017] [Indexed: 01/22/2023]
Abstract
The pathways and mechanisms that regulate pulmonary surfactant synthesis, processing, secretion and catabolism have been extensively characterised using classical biochemical and analytical approaches. These have constructed a model, largely in experimental animals, for surfactant phospholipid metabolism in the alveolar epithelial cell whereby phospholipid synthesised on the endoplasmic reticulum is selectively transported to lamellar body storage vesicles, where it is subsequently processed before secretion into the alveolus. Surfactant phospholipid is a complex mixture of individual molecular species defined by the combination of esterified fatty acid groups and a comprehensive description of surfactant phospholipid metabolism requires consideration of the interactions between such molecular species. However, until recently, lipid analytical techniques have not kept pace with the considerable advances in understanding of the enzymology and molecular biology of surfactant metabolism. Refinements in electrospray ionisation mass spectrometry (ESI-MS) can now provide very sensitive platforms for the rapid characterisation of surfactant phospholipid composition in molecular detail. The combination of ESI-MS and administration of phospholipid substrates labelled with stable isotopes extends this analytical approach to the quantification of synthesis and turnover of individual molecular species of surfactant phospholipid. As this methodology does not involve radioactivity, it is ideally suited to application in clinical studies. This review will provide an overview of the metabolic processes that regulate the molecular specificity of surfactant phosphatidylcholine together with examples of how the application of stable isotope technologies in vivo has, for the first time, begun to explore regulation of the molecular specificity of surfactant synthesis in human subjects.
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Affiliation(s)
- Joost Brandsma
- Academic Unit of Clinical & Experimental Sciences, Faculty of Medicine, University of Southampton, United Kingdom
| | - Anthony D Postle
- Academic Unit of Clinical & Experimental Sciences, Faculty of Medicine, University of Southampton, United Kingdom.
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6
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Olmeda B, Martínez-Calle M, Pérez-Gil J. Pulmonary surfactant metabolism in the alveolar airspace: Biogenesis, extracellular conversions, recycling. Ann Anat 2016; 209:78-92. [PMID: 27773772 DOI: 10.1016/j.aanat.2016.09.008] [Citation(s) in RCA: 73] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Revised: 09/22/2016] [Accepted: 09/25/2016] [Indexed: 01/03/2023]
Abstract
Pulmonary surfactant is a lipid-protein complex that lines and stabilizes the respiratory interface in the alveoli, allowing for gas exchange during the breathing cycle. At the same time, surfactant constitutes the first line of lung defense against pathogens. This review presents an updated view on the processes involved in biogenesis and intracellular processing of newly synthesized and recycled surfactant components, as well as on the extracellular surfactant transformations before and after the formation of the surface active film at the air-water interface. Special attention is paid to the crucial regulation of surfactant homeostasis, because its disruption is associated with several lung pathologies.
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Affiliation(s)
- Bárbara Olmeda
- Department of Biochemistry, Faculty of Biology, and Research Institute "Hospital 12 de Octubre", Complutense University, 28040 Madrid, Spain
| | - Marta Martínez-Calle
- Department of Biochemistry, Faculty of Biology, and Research Institute "Hospital 12 de Octubre", Complutense University, 28040 Madrid, Spain
| | - Jesus Pérez-Gil
- Department of Biochemistry, Faculty of Biology, and Research Institute "Hospital 12 de Octubre", Complutense University, 28040 Madrid, Spain.
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7
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Orgeig S, Morrison JL, Daniels CB. Evolution, Development, and Function of the Pulmonary Surfactant System in Normal and Perturbed Environments. Compr Physiol 2015; 6:363-422. [PMID: 26756637 DOI: 10.1002/cphy.c150003] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Surfactant lipids and proteins form a surface active film at the air-liquid interface of internal gas exchange organs, including swim bladders and lungs. The system is uniquely positioned to meet both the physical challenges associated with a dynamically changing internal air-liquid interface, and the environmental challenges associated with the foreign pathogens and particles to which the internal surface is exposed. Lungs range from simple, transparent, bag-like units to complex, multilobed, compartmentalized structures. Despite this anatomical variability, the surfactant system is remarkably conserved. Here, we discuss the evolutionary origin of the surfactant system, which likely predates lungs. We describe the evolution of surfactant structure and function in invertebrates and vertebrates. We focus on changes in lipid and protein composition and surfactant function from its antiadhesive and innate immune to its alveolar stability and structural integrity functions. We discuss the biochemical, hormonal, autonomic, and mechanical factors that regulate normal surfactant secretion in mature animals. We present an analysis of the ontogeny of surfactant development among the vertebrates and the contribution of different regulatory mechanisms that control this development. We also discuss environmental (oxygen), hormonal and biochemical (glucocorticoids and glucose) and pollutant (maternal smoking, alcohol, and common "recreational" drugs) effects that impact surfactant development. On the adult surfactant system, we focus on environmental variables including temperature, pressure, and hypoxia that have shaped its evolution and we discuss the resultant biochemical, biophysical, and cellular adaptations. Finally, we discuss the effect of major modern gaseous and particulate pollutants on the lung and surfactant system.
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Affiliation(s)
- Sandra Orgeig
- School of Pharmacy & Medical Sciences and Sansom Institute for Health Research, University of South Australia, Adelaide, Australia
| | - Janna L Morrison
- School of Pharmacy & Medical Sciences and Sansom Institute for Health Research, University of South Australia, Adelaide, Australia
| | - Christopher B Daniels
- School of Pharmacy & Medical Sciences and Sansom Institute for Health Research, University of South Australia, Adelaide, Australia
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8
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Lin S, Ikegami M, Moon C, Naren AP, Shannon JM. Lysophosphatidylcholine Acyltransferase 1 (LPCAT1) Specifically Interacts with Phospholipid Transfer Protein StarD10 to Facilitate Surfactant Phospholipid Trafficking in Alveolar Type II Cells. J Biol Chem 2015; 290:18559-74. [PMID: 26048993 DOI: 10.1074/jbc.m115.666701] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2015] [Indexed: 01/10/2023] Open
Abstract
Pulmonary surfactant, a mixture of proteins and phospholipids, plays an important role in facilitating gas exchange by maintaining alveolar stability. Saturated phosphatidylcholine (SatPC), the major component of surfactant, is synthesized both de novo and by the remodeling of unsaturated phosphatidylcholine (PC) by lyso-PC acyltransferase 1 (LPCAT1). After synthesis in the endoplasmic reticulum, SatPC is routed to lamellar bodies (LBs) for storage prior to secretion. The mechanism by which SatPC is transported to LB is not understood. The specificity of LPCAT1 for lyso-PC as an acyl acceptor suggests that formation of SatPC via LPCAT1 reacylation is a final step in SatPC synthesis prior to transport. We hypothesized that LPCAT1 forms a transient complex with SatPC and specific phospholipid transport protein(s) to initiate trafficking of SatPC from the endoplasmic reticulum to the LB. Herein we have assessed the ability of different StarD proteins to interact with LPCAT1. We found that LPCAT1 interacts with StarD10, that this interaction is direct, and that amino acids 79-271 of LPCAT1 and the steroidogenic acute regulatory protein-related lipid transfer (START) domain of START domain-containing protein 10 (StarD10) are sufficient for this interaction. The role of StarD10 in trafficking of phospholipid to LB was confirmed by the observation that knockdown of StarD10 significantly reduced transport of phospholipid to LB. LPCAT1 also interacted with one isoform of StarD7 but showed no interaction with StarD2/PC transfer protein.
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Affiliation(s)
- Sui Lin
- From the Divisions of Pulmonary Biology and
| | | | - Changsuk Moon
- Pulmonary Medicine, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio 45229
| | - Anjaparavanda P Naren
- Pulmonary Medicine, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio 45229
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9
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Abstract
The alveolar type II epithelial (ATII) cell is highly specialised for the synthesis and storage, in intracellular lamellar bodies, of phospholipid destined for secretion as pulmonary surfactant into the alveolus. Regulation of the enzymology of surfactant phospholipid synthesis and metabolism has been extensively characterised at both molecular and functional levels, but understanding of surfactant phospholipid metabolism in vivo in either healthy or, especially, diseased lungs is still relatively poorly understood. This review will integrate recent advances in the enzymology of surfactant phospholipid metabolism with metabolic studies in vivo in both experimental animals and human subjects. It will highlight developments in the application of stable isotope-labelled precursor substrates and mass spectrometry to probe lung phospholipid metabolism in terms of individual molecular lipid species and identify areas where a more comprehensive metabolic model would have considerable potential for direct application to disease states.
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10
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Agassandian M, Mallampalli RK. Surfactant phospholipid metabolism. Biochim Biophys Acta Mol Cell Biol Lipids 2012; 1831:612-25. [PMID: 23026158 DOI: 10.1016/j.bbalip.2012.09.010] [Citation(s) in RCA: 153] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2012] [Revised: 09/07/2012] [Accepted: 09/16/2012] [Indexed: 12/16/2022]
Abstract
Pulmonary surfactant is essential for life and is composed of a complex lipoprotein-like mixture that lines the inner surface of the lung to prevent alveolar collapse at the end of expiration. The molecular composition of surfactant depends on highly integrated and regulated processes involving its biosynthesis, remodeling, degradation, and intracellular trafficking. Despite its multicomponent composition, the study of surfactant phospholipid metabolism has focused on two predominant components, disaturated phosphatidylcholine that confers surface-tension lowering activities, and phosphatidylglycerol, recently implicated in innate immune defense. Future studies providing a better understanding of the molecular control and physiological relevance of minor surfactant lipid components are needed. This article is part of a Special Issue entitled Phospholipids and Phospholipid Metabolism.
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Affiliation(s)
- Marianna Agassandian
- Department of Medicine, Acute Lung Injury Center of Excellence, the University of Pittsburgh, Pittsburgh, PA 15213, USA
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11
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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.
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Affiliation(s)
- Jesús Perez-Gil
- Department Bioquímica, Faculty Biología, Universidad Complutense, Madrid, Spain.
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12
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Osanai K, Higuchi J, Oikawa R, Kobayashi M, Tsuchihara K, Iguchi M, Huang J, Voelker DR, Toga H. Altered lung surfactant system in a Rab38-deficient rat model of Hermansky-Pudlak syndrome. Am J Physiol Lung Cell Mol Physiol 2010; 298:L243-51. [DOI: 10.1152/ajplung.00242.2009] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Several Long-Evans rat substrains carrying the phenotype of oculocutaneous albinism and bleeding diathesis are a rat model of Hermansky-Pudlak syndrome (HPS). The mutation responsible for the phenotype ( Ruby) was identified as a point mutation in the initiation codon of Rab38 small GTPase that regulates intracellular vesicle transport. As patients with HPS often develop life-limiting interstitial pneumonia accompanied by abnormal morphology of alveolar type II cells, we investigated lung surfactant system in Long-Evans Cinnamon rats, one strain of the Ruby rats. The lungs showed conspicuous morphology of type II cells containing markedly enlarged lamellar bodies. Surfactant phosphatidylcholine and surfactant protein B were increased in lung tissues and lamellar bodies but not in alveolar lumen. Expression levels of mRNA for surfactant proteins A, B, C, and D were not altered. Isolated type II cells showed aberrant secretory pattern of newly synthesized [3H]phosphatidylcholine, i.e., decreased basal secretion and remarkably amplified agonist-induced secretion. [3H]phosphatidylcholine synthesis and uptake by type II cells were not altered. Thus Rab38-deficient type II cells appear to carry abnormality in lung surfactant secretion but not in synthesis or uptake. These results suggest that aberrant lung surfactant secretion may be involved in the pathogenesis of interstitial pneumonia in HPS.
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Affiliation(s)
- Kazuhiro Osanai
- Department of Respiratory Medicine, Kanazawa Medical University, Kahokugun, Ishikawa; and
| | - Junko Higuchi
- Department of Human Pathology, Yamagata University Graduate School of Medicine, Yamagata, Yamagata, Japan; and
| | - Rieko Oikawa
- Department of Respiratory Medicine, Kanazawa Medical University, Kahokugun, Ishikawa; and
| | - Makoto Kobayashi
- Department of Respiratory Medicine, Kanazawa Medical University, Kahokugun, Ishikawa; and
| | - Katsuma Tsuchihara
- Department of Respiratory Medicine, Kanazawa Medical University, Kahokugun, Ishikawa; and
| | - Masaharu Iguchi
- Department of Respiratory Medicine, Kanazawa Medical University, Kahokugun, Ishikawa; and
| | - Jyongsu Huang
- Department of Respiratory Medicine, Kanazawa Medical University, Kahokugun, Ishikawa; and
| | | | - Hirohisa Toga
- Department of Respiratory Medicine, Kanazawa Medical University, Kahokugun, Ishikawa; and
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13
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Osanai K, Oikawa R, Higuchi J, Kobayashi M, Tsuchihara K, Iguchi M, Jongsu H, Toga H, Voelker DR. A mutation in Rab38 small GTPase causes abnormal lung surfactant homeostasis and aberrant alveolar structure in mice. THE AMERICAN JOURNAL OF PATHOLOGY 2008; 173:1265-74. [PMID: 18832574 DOI: 10.2353/ajpath.2008.080056] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The chocolate mutation, which is associated with oculocutaneous albinism in mice, has been attributed to a G146T transversion in the conserved GTP/GDP-interacting domain of Rab38, a small GTPase that regulates intracellular vesicular trafficking. Rab38 displays a unique tissue-specific expression pattern with highest levels present in the lung. The purpose of this study was to characterize the effects of Rab38-G146T on lung phenotype and to investigate the molecular basis of the mutant gene product (Rab38(cht) protein). Chocolate lungs exhibited a uniform enlargement of the distal airspaces with mild alveolar destruction as well as a slight increase in lung compliance. Alveolar type II cells were engorged with lamellar bodies of increased size and number. Hydrophobic surfactant constituents (ie, phosphatidylcholine and surfactant protein B) were increased in lung tissues but decreased in alveolar spaces, consistent with a malfunction in lamellar body secretion and the subsequent cellular accumulation of these organelles. In contrast to wild-type Rab38, native Rab38(cht) proteins were found to be hydrophilic and not bound to intracellular membranes. Unexpectedly, recombinant Rab38(cht) proteins retained GTP-binding activity but failed to undergo prenyl modification that is required for membrane-binding activity. These results suggest that the genetic abnormality of Rab38 affects multiple lysosome-related organelles, resulting in lung disease in addition to oculocutaneous albinism.
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Affiliation(s)
- Kazuhiro Osanai
- Department of Respiratory Medicine, Kanazawa Medical University, Kahokugun, Ishikawa 920-0293, Japan.
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14
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Andreeva AV, Kutuzov MA, Voyno-Yasenetskaya TA. Regulation of surfactant secretion in alveolar type II cells. Am J Physiol Lung Cell Mol Physiol 2007; 293:L259-71. [PMID: 17496061 DOI: 10.1152/ajplung.00112.2007] [Citation(s) in RCA: 147] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Molecular mechanisms of surfactant delivery to the air/liquid interface in the lung, which is crucial to lower the surface tension, have been studied for more than two decades. Lung surfactant is synthesized in the alveolar type II cells. Its delivery to the cell surface is preceded by surfactant component synthesis, packaging into specialized organelles termed lamellar bodies, delivery to the apical plasma membrane and fusion. Secreted surfactant undergoes reuptake, intracellular processing, and finally resecretion of recycled material. This review focuses on the mechanisms of delivery of surfactant components to and their secretion from lamellar bodies. Lamellar bodies-independent secretion is also considered. Signal transduction pathways involved in regulation of these processes are discussed as well as disorders associated with their malfunction.
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Affiliation(s)
- Alexandra V Andreeva
- Department of Pharmacology, University of Illinois College of Medicine, Center for Lung and Vascular Biology, Chicago, IL, USA
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Osanai K, Tsuchihara C, Hatta R, Oikawa T, Tsuchihara K, Iguchi M, Seki T, Takahashi M, Huang J, Toga H. Pulmonary surfactant transport in alveolar type II cells. Respirology 2006; 11 Suppl:S70-3. [PMID: 16423277 DOI: 10.1111/j.1440-1843.2006.00813.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Pulmonary surfactant (PS) is a mixture of several lipids (mainly phosphatidylcholine; PC) and four apoproteins (A, B, C and D). The classical hypothesis of PS transport suggests that PS is synthesized in the endoplasmic reticulum and transported to the lamellar body (LB) via the Golgi apparatus. However, recent studies have raised questions regarding this single route. This study examined, independently, the intracellular trafficking route of three different components of PS, that is, PC, SP-A and SP-B. Alveolar type II cells were isolated from Sprague-Dawley rats or Japanese white rabbits. The cells were cultured with either [3H]choline or [35S]methionine/cysteine with or without brefeldin A, which disassembles the Golgi apparatus. LB was purified from disintegrated cells with sucrose density gradient centrifugation. [3H]PC was extracted from radiolabeled media, cells, and the LB fraction with Bligh-Dyer's method. [35S]SP-A or [35S]SP-B was immunoprecipitated from each sample with a specific antibody. [3H]PC was transported and stored to the LB via a Golgi-independent pathway. [35S]SP-A was transported to the Golgi apparatus, underwent glycosylation, and was then constitutively secreted. The secreted [35S]SP-A was re-uptaken into the LB. [35S]SP-B was transported and stored to the LB via the Golgi-dependent pathway. These results indicate that, rather than a single route, surfactant components take different pathways to reside in the LB. These different pathways may reflect the different nature and role of each surfactant component such as surface tension-lowering activity and innate host defense.
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Affiliation(s)
- Kazuhiro Osanai
- Department of Respiratory Medicine, Kanazawa Medical University, Ishikawa, Japan.
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Osanai K, Takahashi K, Nakamura K, Takahashi M, Ishigaki M, Sakuma T, Toga H, Suzuki T, Voelker DR. Expression and characterization of Rab38, a new member of the Rab small G protein family. Biol Chem 2005; 386:143-53. [PMID: 15843158 DOI: 10.1515/bc.2005.018] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Rab38 is a new member of the Rab small G protein family that regulates intracellular vesicle trafficking. Rab38 is expressed in melanocytes and it has been clarified that a point mutation in the postulated GTP-binding domain of Rab38 is the gene responsible for oculocutaneous albinism in chocolate mice. However, basic information regarding recombinant protein production, intracellular location, and tissue-specific expression pattern has not yet been reported. We produced recombinant Rab38 using a baculovirus/insect cell-protein expression system. A combination of Triton X-114 phase separation and nickel-affinity chromatography yielded exclusively prenylated Rab38 that bound [alpha-32P]-GTP. The mRNA and the native protein were expressed in a tissue-specific manner, e.g., in the lung, skin, stomach, liver, and kidney. Freshly isolated rat alveolar type II cells were highly positive for the mRNA signal, but the signal was rapidly lost over time. Immunofluorescence staining demonstrated that expressed GST-tagged Rab38 was mainly co-localized with endoplasmic reticulum-resident protein and also partly with intermittent vesicles between the endoplasmic reticulum and the Golgi complex. These results indicate that Rab38 is expressed non-ubiquitously in specific tissues and regulates early vesicle transport relating to the endoplasmic reticulum, and hence suggest that Rab38 abnormality may cause multiple organ diseases as well as oculocutaneous albinism.
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Affiliation(s)
- Kazuhiro Osanai
- Department of Respiratory Medicine, Kanazawa Medical University, 1-1 Daigaku-Uchinada, Kahokugun, Ishikawa 920-0293, Japan.
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Birner R, Daum G. Biogenesis and cellular dynamics of aminoglycerophospholipids. INTERNATIONAL REVIEW OF CYTOLOGY 2003; 225:273-323. [PMID: 12696595 DOI: 10.1016/s0074-7696(05)25007-6] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Aminoglycerophospholipids phosphatidylserine (PtdSer), phosphatidylethanolamine (PtdEtn), and phosphatidylcholine (PtdCho) comprise about 80% of total cellular phospholipids in most cell types. While the major function of PtdCho in eukaryotes and PtdEtn in prokaryotes is that of bulk membrane lipids, PtdSer is a minor component and appears to play a more specialized role in the plasma membrane of eukaryotes, e.g., in cell recognition processes. All three aminoglycerophospholipid classes are essential in mammals, whereas prokaryotes and lower eukaryotes such as yeast appear to be more flexible regarding their aminoglycerophospholipid requirement. Since different subcellular compartments of eukaryotes, namely the endoplasmic reticulum and mitochondria, contribute to the biosynthetic sequence of aminoglycerophospholipid formation, intracellular transport, sorting, and specific function of these lipids in different organelles are of special interest.
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Affiliation(s)
- Ruth Birner
- Institut für Biochemie, Technische Universität Graz, Petersgasse 12/2, A-8010 Graz, Austria
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Weaver TE, Na CL, Stahlman M. Biogenesis of lamellar bodies, lysosome-related organelles involved in storage and secretion of pulmonary surfactant. Semin Cell Dev Biol 2003; 13:263-70. [PMID: 12243725 DOI: 10.1016/s1084952102000551] [Citation(s) in RCA: 162] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Lamellar bodies are members of a subclass of lysosome-related organelles referred to as secretory lysosomes. The principal constituents of the lamellar body, surfactant phospholipids, are organized into tightly packed, bilayer membranes in a process that is strongly influenced by the lung-specific, hydrophobic peptide SP-B. Newly synthesized SP-B is transported from the Golgi to the lamellar body via multivesicular bodies; in contrast, preliminary evidence suggests that newly synthesized surfactant phospholipids are transported from the ER and incorporated into the internal membranes of the lamellar body via a distinct pathway.
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Affiliation(s)
- Timothy E Weaver
- Division of Pulmonary Biology, Cincinnati Children's Hospital Medical Center, 3333 Burnet Avenue, Cincinnati, OH 45229-3039, USA.
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Wright MM, McMaster CR. PC and PE synthesis: mixed micellar analysis of the cholinephosphotransferase and ethanolaminephosphotransferase activities of human choline/ethanolamine phosphotransferase 1 (CEPT1). Lipids 2002; 37:663-72. [PMID: 12216837 DOI: 10.1007/s11745-002-0947-6] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The human choline/ethanolamine phosphotransferase 1 (CEPT1) gene codes for a dual-specificity enzyme that catalyzes the de novo synthesis of the two major phospholipids through the transfer of a phosphobase from CDP-choline or CDP-ethanolamine to DAG to form PC and PE. We used an expression system devoid of endogenous cholinephosphotransferase and ethanolaminephosphotransferase activities to assess the diradylglycerol specificity of CEPT1. A mixed micellar assay was used to ensure that the diradylglycerols delivered were not affecting the membrane environment in which CEPT1 resides. The CEPT1 enzyme displayed an apparent Km of 36 microM for CDP-choline and 4.2 mol% for di-18:1 DAG with a Vmax of 14.3 nmol min(-1) mg(-1). When CDP-ethanolamine was used as substrate, the apparent Km was 98 microM for CDP-ethanolamine and 4.3 mol% for di-18:1 DAG with a Vmax of 8.2 nmol min(-1) mg(-1). The preferred diradylglycerol substrates used by CEPT1 with CDP-choline as the phosphobase donor were di-18:1 DAG, di-16:1 DAG, and 16:0/18:1 DAG. A major difference between previous emulsion-based assay results and the mixed micelle results was a complete inability to use 16:0(O)/2:0 as a substrate for the de novo synthesis of platelet-activating factor when the mixed micelle assay was used. When CDP-ethanolamine was used as the phosphobase donor, 16:0/18:1 DAG, di-18:1 DAG, and di-16:1 DAG were the preferred substrates. The mixed micelle assay also allowed the lipid activation of CEPT to be measured, and both the cholinephosphotransferase and ethanolaminephosphotransferase activities displayed the unusual property of product activation at 5 mol%, implying that specific lipid activation binding sites exist on CEPT1. The protein kinase C inhibitor chelerythrine and the human DAG kinase inhibitor R59949 both inhibited CEPT1 activity with IC50 values of 40 microM.
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Affiliation(s)
- Marcia M Wright
- Atlantic Research Centre, Department of Pediatrics, IWK Health Centre, Dalhousie University, Halifax, Nova Scotia, Canada
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