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Floros J, Tsotakos N. Differential Regulation of Human Surfactant Protein A Genes, SFTPA1 and SFTPA2, and Their Corresponding Variants. Front Immunol 2021; 12:766719. [PMID: 34917085 PMCID: PMC8669794 DOI: 10.3389/fimmu.2021.766719] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2021] [Accepted: 11/02/2021] [Indexed: 11/26/2022] Open
Abstract
The human SFTPA1 and SFTPA2 genes encode the surfactant protein A1 (SP-A1) and SP-A2, respectively, and they have been identified with significant genetic and epigenetic variability including sequence, deletion/insertions, and splice variants. The surfactant proteins, SP-A1 and SP-A2, and their corresponding variants play important roles in several processes of innate immunity as well in surfactant-related functions as reviewed elsewhere [1]. The levels of SP-A have been shown to differ among individuals both under baseline conditions and in response to various agents or disease states. Moreover, a number of agents have been shown to differentially regulate SFTPA1 and SFTPA2 transcripts. The focus in this review is on the differential regulation of SFTPA1 and SFTPA2 with primary focus on the role of 5′ and 3′ untranslated regions (UTRs) and flanking sequences on this differential regulation as well molecules that may mediate the differential regulation.
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Affiliation(s)
- Joanna Floros
- Department of Pediatrics, The Pennsylvania State University College of Medicine, Hershey, PA, United States.,Department of Obstetrics and Gynecology, The Pennsylvania State University College of Medicine, Hershey, PA, United States
| | - Nikolaos Tsotakos
- School of Science, Engineering, and Technology, The Pennsylvania State University - Harrisburg, Middletown, PA, United States
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2
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Tekos F, Skaperda Z, Goutzourelas N, Phelps DS, Floros J, Kouretas D. The Importance of Redox Status in the Frame of Lifestyle Approaches and the Genetics of the Lung Innate Immune Molecules, SP-A1 and SP-A2, on Differential Outcomes of COVID-19 Infection. Antioxidants (Basel) 2020; 9:antiox9090784. [PMID: 32854247 PMCID: PMC7554878 DOI: 10.3390/antiox9090784] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Revised: 08/20/2020] [Accepted: 08/21/2020] [Indexed: 02/07/2023] Open
Abstract
The pandemic of COVID-19 is of great concern to the scientific community. This mainly affects the elderly and people with underlying diseases. People with obesity are more likely to experience unpleasant disease symptoms and increased mortality. The severe oxidative environment that occurs in obesity due to chronic inflammation permits viral activation of further inflammation leading to severe lung disease. Lifestyle affects the levels of inflammation and oxidative stress. It has been shown that a careful diet rich in antioxidants, regular exercise, and fasting regimens, each and/or together, can reduce the levels of inflammation and oxidative stress and strengthen the immune system as they lead to weight loss and activate cellular antioxidant mechanisms and reduce oxidative damage. Thus, a lifestyle change based on the three pillars: antioxidants, exercise, and fasting could act as a proactive preventative measure against the adverse effects of COVID-19 by maintaining redox balance and well-functioning immunity. Moreover, because of the observed diversity in the expression of COVID-19 inflammation, the role of genetics of innate immune molecules, surfactant protein A (SP-A)1 and SP-A2, and their differential impact on the local lung microenvironment and host defense is reviewed as genetics may play a major role in the diverse expression of the disease.
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Affiliation(s)
- Fotios Tekos
- Department of Biochemistry-Biotechnology, University of Thessaly, 41500 Larissa, Greece; (F.T.); (Z.S.); (N.G.)
| | - Zoi Skaperda
- Department of Biochemistry-Biotechnology, University of Thessaly, 41500 Larissa, Greece; (F.T.); (Z.S.); (N.G.)
| | - Nikolaos Goutzourelas
- Department of Biochemistry-Biotechnology, University of Thessaly, 41500 Larissa, Greece; (F.T.); (Z.S.); (N.G.)
| | - David S. Phelps
- Center for Host Defense, Inflammation, and Lung Disease (CHILD) and Departments of Pediatrics, Hershey, PA 17033, USA; (D.S.P.); (J.F.)
| | - Joanna Floros
- Center for Host Defense, Inflammation, and Lung Disease (CHILD) and Departments of Pediatrics, Hershey, PA 17033, USA; (D.S.P.); (J.F.)
- Obstetrics & Gynecology, Pennsylvania State University College of Medicine, Hershey, PA 17033, USA
| | - Demetrios Kouretas
- Department of Biochemistry-Biotechnology, University of Thessaly, 41500 Larissa, Greece; (F.T.); (Z.S.); (N.G.)
- Correspondence: ; Tel.: +30-2410-565-277; Fax: +30-2410-565-290
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Noutsios GT, Thorenoor N, Zhang X, Phelps DS, Umstead TM, Durrani F, Floros J. Major Effect of Oxidative Stress on the Male, but Not Female, SP-A1 Type II Cell miRNome. Front Immunol 2019; 10:1514. [PMID: 31354704 PMCID: PMC6635478 DOI: 10.3389/fimmu.2019.01514] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2018] [Accepted: 06/17/2019] [Indexed: 11/15/2022] Open
Abstract
Pulmonary surfactant protein A (SP-A) plays an important role in surfactant metabolism and lung innate immunity. In humans there are two proteins, SP-A1 and SP-A2, encoded by SFTPA1 and SFTPA2, respectively, which are produced by the alveolar type II cells (T2C). We sought to investigate the differential influence of SP-A1 and SP-A2 in T2C miRNome under oxidative stress (OxS). SP-A knock out (KO) and hTG male and female mice expressing SP-A1 or SP-A2 as well as gonadectomized (Gx) mice were exposed to O3-induced oxidative stress (OxS) or filtered air (FA). Expression of miRNAs and mRNAs was measured in the T2C of experimental animals. (a) In SP-A1 males after normalizing to KO males, significant changes were observed in the miRNome in terms of sex-OxS effects, with 24 miRNAs being differentially expressed under OxS. (b) The mRNA targets of the dysregulated miRNAs included Ago2, Ddx20, Plcg2, Irs1, Elf2, Jak2, Map2k4, Bcl2, Ccnd1, and Vhl. We validated the expression levels of these transcripts, and observed that the mRNA levels of all of these targets were unaffected in SP-A1 T2C but six of these were significantly upregulated in the KO (except Bcl2 that was downregulated). (c) Gondadectomy had a major effect on the expression of miRNAs and in three of the mRNA targets (Irs1, Bcl2, and Vhl). Ccnd1 was upregulated in KO regardless of Gx. (d) The targets of the significantly changed miRNAs are involved in several pathways including MAPK signaling pathway, cell cycle, anti-apoptosis, and other. In conclusion, in response to OxS, SP-A1 and male hormones appear to have a major effect in the T2C miRNome.
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Affiliation(s)
- George T Noutsios
- Center for Host Defense, Inflammation, and Lung Disease (CHILD) Research, Department of Pediatrics, College of Medicine, Pennsylvania State University, Hershey, PA, United States
| | - Nithyananda Thorenoor
- Center for Host Defense, Inflammation, and Lung Disease (CHILD) Research, Department of Pediatrics, College of Medicine, Pennsylvania State University, Hershey, PA, United States
| | - Xuesheng Zhang
- Center for Host Defense, Inflammation, and Lung Disease (CHILD) Research, Department of Pediatrics, College of Medicine, Pennsylvania State University, Hershey, PA, United States
| | - David S Phelps
- Center for Host Defense, Inflammation, and Lung Disease (CHILD) Research, Department of Pediatrics, College of Medicine, Pennsylvania State University, Hershey, PA, United States
| | - Todd M Umstead
- Center for Host Defense, Inflammation, and Lung Disease (CHILD) Research, Department of Pediatrics, College of Medicine, Pennsylvania State University, Hershey, PA, United States
| | - Faryal Durrani
- Center for Host Defense, Inflammation, and Lung Disease (CHILD) Research, Department of Pediatrics, College of Medicine, Pennsylvania State University, Hershey, PA, United States
| | - Joanna Floros
- Center for Host Defense, Inflammation, and Lung Disease (CHILD) Research, Department of Pediatrics, College of Medicine, Pennsylvania State University, Hershey, PA, United States.,Department of Obstetrics and Gynecology, College of Medicine, Pennsylvania State University, Hershey, PA, United States
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4
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Innovative methods for biomarker discovery in the evaluation and development of cancer precision therapies. Cancer Metastasis Rev 2018; 37:125-145. [PMID: 29392535 DOI: 10.1007/s10555-017-9710-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The discovery of biomarkers able to detect cancer at an early stage, to evaluate its aggressiveness, and to predict the response to therapy remains a major challenge in clinical oncology and precision medicine. In this review, we summarize recent achievements in the discovery and development of cancer biomarkers. We also highlight emerging innovative methods in biomarker discovery and provide insights into the challenges faced in their evaluation and validation.
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Shao Y, Li JX, Ge RL, Zhong L, Irwin DM, Murphy RW, Zhang YP. Genetic adaptations of the plateau zokor in high-elevation burrows. Sci Rep 2015; 5:17262. [PMID: 26602147 PMCID: PMC4658562 DOI: 10.1038/srep17262] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Accepted: 10/27/2015] [Indexed: 12/21/2022] Open
Abstract
The plateau zokor (Myospalax baileyi) spends its entire life underground in sealed burrows. Confronting limited oxygen and high carbon dioxide concentrations, and complete darkness, they epitomize a successful physiological adaptation. Here, we employ transcriptome sequencing to explore the genetic underpinnings of their adaptations to this unique habitat. Compared to Rattus norvegicus, genes belonging to GO categories related to energy metabolism (e.g. mitochondrion and fatty acid beta-oxidation) underwent accelerated evolution in the plateau zokor. Furthermore, the numbers of positively selected genes were significantly enriched in the gene categories involved in ATPase activity, blood vessel development and respiratory gaseous exchange, functional categories that are relevant to adaptation to high altitudes. Among the 787 genes with evidence of parallel evolution, and thus identified as candidate genes, several GO categories (e.g. response to hypoxia, oxygen homeostasis and erythrocyte homeostasis) are significantly enriched, are two genes, EPAS1 and AJUBA, involved in the response to hypoxia, where the parallel evolved sites are at positions that are highly conserved in sequence alignments from multiple species. Thus, accelerated evolution of GO categories, positive selection and parallel evolution at the molecular level provide evidences to parse the genetic adaptations of the plateau zokor for living in high-elevation burrows.
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Affiliation(s)
- Yong Shao
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, the Chinese Academy of Sciences, Kunming 650223, China.,Kunming College of Life Science, University of the Chinese Academy of Sciences, Kunming 650204, China
| | - Jin-Xiu Li
- Laboratory for Conservation and Utilization of Bio-resources, Yunnan University, Kunming 650091, China
| | - Ri-Li Ge
- Key Laboratory for High Altitude Medicine of Ministry of Chinese Education and Research Center for High Altitude Medicine, Qinghai University, Xining 810001, China
| | - Li Zhong
- Laboratory for Conservation and Utilization of Bio-resources, Yunnan University, Kunming 650091, China
| | - David M Irwin
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, the Chinese Academy of Sciences, Kunming 650223, China.,Department of Laboratory Medicine and Pathobiology, University of Toronto, Ontario, M5S 1A8, Canada.,Banting and Best Diabetes Centre, University of Toronto, Ontario, M5S 1A8, Canada
| | - Robert W Murphy
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, the Chinese Academy of Sciences, Kunming 650223, China.,Centre for Biodiversity and Conservation Biology, Royal Ontario Museum, 100 Queen's Park, Toronto, Ont., M5S 2C6, Canada
| | - Ya-Ping Zhang
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, the Chinese Academy of Sciences, Kunming 650223, China.,Laboratory for Conservation and Utilization of Bio-resources, Yunnan University, Kunming 650091, China
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Abstract
A majority of messenger RNA precursors (pre-mRNAs) in the higher eukaryotes undergo alternative splicing to generate more than one mature product. By targeting the open reading frame region this process increases diversity of protein isoforms beyond the nominal coding capacity of the genome. However, alternative splicing also frequently controls output levels and spatiotemporal features of cellular and organismal gene expression programs. Here we discuss how these non-coding functions of alternative splicing contribute to development through regulation of mRNA stability, translational efficiency and cellular localization.
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Tolosa MF, Palaniyar N. Severe respiratory insufficiency during pandemic H1N1 infection: prognostic value and therapeutic potential of pulmonary surfactant protein A. CRITICAL CARE : THE OFFICIAL JOURNAL OF THE CRITICAL CARE FORUM 2014; 18:479. [PMID: 25184962 PMCID: PMC4423634 DOI: 10.1186/s13054-014-0479-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 06/25/2014] [Accepted: 07/24/2014] [Indexed: 12/20/2022]
Abstract
For almost two decades, studies have shown collectins to be critical for effective antimicrobial defense of the airways. Members of this protein family, which includes surfactant proteins (SP)-A and D, provide broad-spectrum protection through promoting the aggregation and clearance of pathogens. Interestingly, these proteins may also modulate the immune response, and growing evidence has shown collectins to be protective against several markers of inflammation and injury. In a recent study by Herrera-Ramos and colleagues, genetic variants of collectins were examined in Spanish patients with the pandemic 2009 H1N1 influenza A virus. Comparing genotypes for measures of poor lung function, inflammation, and admission to intensive care, these authors identified three variants of the SP-A gene SFTPA2 that positively correlated with flu severity. Remarkably, they also found the haplotype 1A1 of SFTPA2 to be protective against these indicators, suggesting that targeted therapy with a recombinant form of SP-A2 may improve patient outcome. Although further work is required to confirm the specificity and efficacy of SP-A in therapeutic H1N1 protection, this study is one of the first to suggest a clinical role for SP-A in pandemic influenza.
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Affiliation(s)
- Monica Fern Tolosa
- Program in Physiology and Experimental Medicine, Peter Gilgan Centre for Research and Learning, The Hospital for Sick Children, 686 Bay Street, Toronto, ON, M5G 0A4, Canada. .,Department of Laboratory Medicine and Pathobiology, Faculty of Medicine, University of Toronto, 1 King's College Circle, Toronto, ON, M5S 1A8, Canada.
| | - Nades Palaniyar
- Program in Physiology and Experimental Medicine, Peter Gilgan Centre for Research and Learning, The Hospital for Sick Children, 686 Bay Street, Toronto, ON, M5G 0A4, Canada. .,Department of Laboratory Medicine and Pathobiology, Faculty of Medicine, University of Toronto, 1 King's College Circle, Toronto, ON, M5S 1A8, Canada. .,Institute of Medical Sciences, Faculty of Medicine, University of Toronto, 1 King's College Circle, Toronto, ON, M5S 1A8, Canada.
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Silveyra P, Chroneos ZC, DiAngelo SL, Thomas NJ, Noutsios GT, Tsotakos N, Howrylak JA, Umstead TM, Floros J. Knockdown of Drosha in human alveolar type II cells alters expression of SP-A in culture: a pilot study. Exp Lung Res 2014; 40:354-66. [PMID: 25058539 DOI: 10.3109/01902148.2014.929757] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Human surfactant protein A (SP-A) plays an important role in surfactant metabolism and lung innate immunity. SP-A is synthesized and secreted by alveolar type II (ATII) cells, one of the two cell types of the distal lung epithelium (ATII and ATI). We have shown that miRNA interactions with sequence polymorphisms on the SP-A mRNA 3'UTRs mediate differential expression of SP-A1 and SP-A2 gene variants in vitro. In the present study, we describe a physiologically relevant model to study miRNA regulation of SP-A in human ATII. For these studies, we purified and cultured human ATII on an air-liquid interface matrix (A/L) or plastic wells without matrix (P). Gene expression analyses confirmed that cells cultured in A/L maintained the ATII phenotype for over 5 days, whereas P-cultured cells differentiated to ATI. When we transfected ATII with siRNAs to inhibit the expression of Drosha, a critical effector of miRNA maturation, the levels of SP-A mRNA and protein increased in a time dependent manner. We next characterized cultured ATII and ATI by studying expression of 1,066 human miRNAs using miRNA PCR arrays. We detected expression of >300 miRNAs with 24 miRNAs differentially expressed in ATII versus ATI, 12 of which predicted to bind SP-A 3'UTRs, indicating that these may be implicated in SP-A downregulation in ATI. Thus, miRNAs not only affect SP-A expression, but also may contribute to the maintenance of the ATII cell phenotype and/or the trans-differentiation of ATII to ATI cells, and may represent new molecular markers that distinguish ATII and ATI.
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Affiliation(s)
- Patricia Silveyra
- 1Center for Host Defense, Inflammation, and Lung Disease (CHILD) Research, Department of Pediatrics, The Pennsylvania State University College of Medicine , Hershey, Pennsylvania , USA
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9
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Silveyra P, DiAngelo SL, Floros J. An 11-nt sequence polymorphism at the 3'UTR of human SFTPA1 and SFTPA2 gene variants differentially affect gene expression levels and miRNA regulation in cell culture. Am J Physiol Lung Cell Mol Physiol 2014; 307:L106-19. [PMID: 24793167 DOI: 10.1152/ajplung.00313.2013] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Surfactant protein A (SP-A) plays a vital role in maintaining normal lung function and in host defense. Two genes encode SP-A in humans (SFTPA1, SFTPA2), and several gene variants have been identified for these. We have previously shown that sequence elements of SFTPA1 and SFTPA2 3' untranslated regions (UTRs) differentially affect translation efficiency in vitro. Polymorphisms at the 3'UTRs of mRNA variants may account for differential binding of miRNAs, a class of small noncoding RNAs that regulate gene expression. In this work, we generated 3'UTR reporter constructs of the SFTPA1 and SFTPA2 variants most frequently found in the population, as well as mutants of a previously described 11-nt indel element (refSNP rs368700152). Reporter constructs were transfected in NCI-H441 cells in the presence or absence of miRNA mimics, and reporter gene expression was analyzed. We found that human miRNA mir-767 negatively affected expression of constructs containing SFTPA1 and SFTPA2 variants, whereas mir-4507 affected only constructs with 3'UTRs of SFTPA1 variants 6A, 6A(3), and 6A(4) (not containing the 11-nt element). Three miRNAs (mir-183, mir-449b, and mir-612) inhibited expression of recombinants of SFTPA2 variants and the SFTPA1 variant 6A(2), all containing the 11-nt element. Similar results were obtained for SP-A expression when these miRNAs were transfected in Chinese hamster ovary cells expressing SFTPA1 or SFTPA2 variants or in NCI-H441 cells (genotype 1A(5)/1A(5)-6A(4)/6A(4)). Moreover, transfection with a specific antagomir (antagomir-183) reversed the effects of mir-183 on SP-A mRNA levels. Our results indicate that sequence variability at the 3'UTR of SP-A variants differentially affects miRNA regulation of gene expression.
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Affiliation(s)
- Patricia Silveyra
- Center for Host Defense, Inflammation, and Lung Disease (CHILD) Research, Department of Pediatrics, Department of Biochemistry and Molecular Biology; and
| | - Susan L DiAngelo
- Center for Host Defense, Inflammation, and Lung Disease (CHILD) Research, Department of Pediatrics
| | - Joanna Floros
- Center for Host Defense, Inflammation, and Lung Disease (CHILD) Research, Department of Pediatrics, Department of Obstetrics and Gynecology, Penn State Hershey College of Medicine, Pennsylvania State University, Hershey, Pennsylvania
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Noutsios GT, Silveyra P, Bhatti F, Floros J. Exon B of human surfactant protein A2 mRNA, alone or within its surrounding sequences, interacts with 14-3-3; role of cis-elements and secondary structure. Am J Physiol Lung Cell Mol Physiol 2013; 304:L722-35. [PMID: 23525782 PMCID: PMC3680765 DOI: 10.1152/ajplung.00324.2012] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2012] [Accepted: 03/03/2013] [Indexed: 01/22/2023] Open
Abstract
Human surfactant protein A, an innate immunity molecule, is encoded by two genes: SFTPA1 (SP-A1) and SFTPA2 (SP-A2). The 5' untranslated (5'UTR) splice variant of SP-A2 (ABD), but not of SP-A1 (AD), contains exon B (eB), which is an enhancer for transcription and translation. We investigated whether eB contains cis-regulatory elements that bind trans-acting factors in a sequence-specific manner as well as the role of the eB mRNA secondary structure. Binding of cytoplasmic NCI-H441 proteins to wild-type eB, eB mutant, AD, and ABD 5'UTR mRNAs were studied by RNA electromobility shift assays (REMSAs). The bound proteins were identified by mass spectroscopy and specific antibodies (Abs). We found that 1) proteins bind eB mRNA in a sequence-specific manner, with two cis-elements identified within eB to be important; 2) eB secondary structure is necessary for binding; 3) mass spectroscopy and specific Abs in REMSAs identified 14-3-3 proteins to bind (directly or indirectly) eB and the natural SP-A2 (ABD) splice variant but not the SP-A1 (AD) splice variant; 4) other ribosomal and cytoskeletal proteins, and translation factors, are also present in the eB mRNA-protein complex; 5) knockdown of 14-3-3 β/α isoform resulted in a downregulation of SP-A2 expression. In conclusion, proteins including the 14-3-3 family bind two cis-elements within eB of hSP-A2 mRNA in a sequence- and secondary structure-specific manner. Differential regulation of SP-A1 and SP-A2 is mediated by the 14-3-3 protein family as well as by a number of other proteins that bind UTRs with or without eB mRNA.
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Affiliation(s)
- Georgios T Noutsios
- Center for Host Defense, Inflammation, and Lung Disease (CHILD) Research Department of Pediatrics, College of Medicine, The Pennsylvania State University, Hershey, PA 17033, USA
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Silveyra P, Floros J. Genetic complexity of the human surfactant-associated proteins SP-A1 and SP-A2. Gene 2012; 531:126-32. [PMID: 23069847 DOI: 10.1016/j.gene.2012.09.111] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2012] [Revised: 09/08/2012] [Accepted: 09/29/2012] [Indexed: 01/08/2023]
Abstract
Pulmonary surfactant protein A (SP-A) plays a key role in innate lung host defense, in surfactant-related functions, and in parturition. In the course of evolution, the genetic complexity of SP-A has increased, particularly in the regulatory regions (i.e. promoter, untranslated regions). Although most species have a single SP-A gene, two genes encode SP-A in humans and primates (SFTPA1 and SFTPA2). This may account for the multiple functions attributed to human SP-A, as well as the regulatory complexity of its expression by a relatively diverse set of protein and non-protein cellular factors. The interplay between enhancer cis-acting DNA sequences and trans-acting proteins that recognize these DNA elements is essential for gene regulation, primarily at the transcription initiation level. Furthermore, regulation at the mRNA level is essential to ensure proper physiological levels of SP-A under different conditions. To date, numerous studies have shown significant complexity of the regulation of SP-A expression at different levels, including transcription, splicing, mRNA decay, and translation. A number of trans-acting factors have also been described to play a role in the control of SP-A expression. The aim of this report is to describe the genetic complexity of the SFTPA1 and SFTPA2 genes, as well as to review regulatory mechanisms that control SP-A expression in humans and other animal species.
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Affiliation(s)
- Patricia Silveyra
- Center for Host Defense, Inflammation, and Lung Disease (CHILD) Research, Department of Pediatrics, Pennsylvania State University College of Medicine, Hershey, PA, 17033, USA
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12
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Silveyra P, Floros J. Air pollution and epigenetics: effects on SP-A and innate host defence in the lung. Swiss Med Wkly 2012; 142:w13579. [PMID: 22553125 DOI: 10.4414/smw.2012.13579] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
An appropriate immune and inflammatory response is key to defend against harmful agents present in the environment, such as pathogens, allergens and inhaled pollutants, including ozone and particulate matter. Air pollution is a serious public health concern worldwide, and cumulative evidence has revealed that air pollutants contribute to epigenetic variation in several genes, and this in turn can contribute to disease susceptibility. Several groups of experts have recently reviewed findings on epigenetics and air pollution [1-6]. Surfactant proteins play a central role in pulmonary host defence by mediating pathogen clearance, modulating allergic responses and facilitating the resolution of lung inflammation. Recent evidence indicates that surfactant proteins are subject to epigenetic regulation under hypoxia and other conditions. Oxidative stress caused by ozone, and exposure to particulate matter have been shown to affect the expression of surfactant protein A (SP-A), an important lung host defence molecule, as well as alter its functions. In this review, we discuss recent findings in the fields of epigenetics and air pollution effects on innate immunity, with the focus on SP-A, and the human SP-A variants in particular. Their function may be differentially affected by pollutants and specifically by ozone-induced oxidative stress, and this in turn may differentially affect susceptibility to lung disease.
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Affiliation(s)
- Patricia Silveyra
- Center for Host Defense, Inflammation, and Lung Disease (CHILD) Research, Department of Pediatrics, Pennsylvania State University College of Medicine, Hershey, USA
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Silveyra P, Floros J. Genetic variant associations of human SP-A and SP-D with acute and chronic lung injury. Front Biosci (Landmark Ed) 2012; 17:407-29. [PMID: 22201752 DOI: 10.2741/3935] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Pulmonary surfactant, a lipoprotein complex, maintains alveolar integrity and plays an important role in lung host defense, and control of inflammation. Altered inflammatory processes and surfactant dysfunction are well described events that occur in patients with acute or chronic lung disease that can develop secondary to a variety of insults. Genetic variants of surfactant proteins, including single nucleotide polymorphisms, haplotypes, and other genetic variations have been associated with acute and chronic lung disease throughout life in several populations and study groups. The hydrophilic surfactant proteins SP-A and SP-D, also known as collectins, in addition to their surfactant-related functions, are important innate immunity molecules as these, among others, exhibit the ability to bind and enhance clearance of a wide range of pathogens and allergens. This review focuses on published association studies of human surfactant proteins A and D genetic polymorphisms with respiratory, and non-respiratory diseases in adults, children, and newborns. The potential role of genetic variations in pulmonary disease or pathogenesis is discussed following an evaluation, and comparison of the available literature.
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Affiliation(s)
- Patricia Silveyra
- Center for Host Defense, Inflammation, and Lung Disease Research, Department of Pediatrics, Pennsylvania State University College of Medicine, Pennsylvania, USA
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14
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Silveyra P, Raval M, Simmons B, Diangelo S, Wang G, Floros J. The untranslated exon B of human surfactant protein A2 mRNAs is an enhancer for transcription and translation. Am J Physiol Lung Cell Mol Physiol 2011; 301:L795-803. [PMID: 21840962 DOI: 10.1152/ajplung.00439.2010] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Two human genes, SFTPA1 (SP-A1) and SFTPA2 (SP-A2), encode surfactant protein A, a molecule of innate immunity and surfactant-related functions. Several genetic variants have been identified for both genes. These include nucleotide (nt) polymorphisms, as well as alternative splicing patterns at the 5' untranslated region (5'UTR). Exon B (eB) is included in the 5'UTR of most SP-A2, but not SP-A1 splice variants. We investigated the role of eB in the regulation of gene expression and translation efficiency. A luciferase (Luc) reporter gene was cloned downstream of the entire (AeBD) or eB deletion mutants (del_mut) of the SP-A2 5'UTR, or heterologous 5'UTRs containing the eB sequence, or a random sequence of equal length. The del_mut constructs consisted in consecutive deletions of five nucleotides (n = 8) within eB and the exon-exon junctions in the AeBD 5'UTR. Luc activities and mRNA levels were compared after transfection of NCI-H441 cells. We found that 1) eB increased Luc mRNA levels when placed upstream of heterologous 5'UTR sequences or the promoter region, regardless of its position and orientation; 2) translation efficiency of in vitro-generated mRNAs containing eB was higher than that of mRNAs without eB; and 3) the integrity of eB sequence is crucial for transcription and translation of the reporter gene. Thus eB 1) is a transcription enhancer, because it increases mRNA content regardless of position and orientation, 2) enhances translation when placed in either orientation within its natural 5'UTR sequence and in heterologous 5'UTRs, and 3) contains potential regulatory elements for both transcription and translation. We conclude that eB sequence and length are determinants of transcription and translation efficiency.
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Affiliation(s)
- Patricia Silveyra
- Center for Host Defense, Inflammation, and Lung Disease Research, Department of Pediatrics, Hershey, Pennsylvania 17033-0850, USA
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Floros J, Thomas NJ. Surfactant protein genetics in community-acquired pneumonia: balancing the host inflammatory state. CRITICAL CARE : THE OFFICIAL JOURNAL OF THE CRITICAL CARE FORUM 2011; 15:156. [PMID: 21575284 PMCID: PMC3219372 DOI: 10.1186/cc10115] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Community-acquired pneumonia is a common disease. Abnormalities in the first step of host defense may severely compromise subsequent steps of successfully combating infections. In the previous issue of Critical Care, García-Laorden and colleagues reported genetic associations between single-nucleotide polymorphisms and haplotypes of the surfactant proteins with susceptibility, severity, and outcome of community-acquired pneumonia. Although the limited information shows regulatory differences among variants, it is currently unknown how the difference in surfactant protein A genotypes in this and other studies affects the individual's phenotype. The lung is continually exposed to a host of irritants yet maintains health. It is plausible that, under physiologic conditions, surfactant protein A, in addition to having a dominant effect on anti-inflammatory processes, mediates a low level of proinflammatory processes that are essential for the health of the lung. Understanding the maintenance of the balance of the inflammatory state may be one of the keys to understanding pulmonary disease progression.
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Affiliation(s)
- Joanna Floros
- Department of Pediatrics, Center for Host defense, Inflammation, and Lung Disease Research, 500 University Drive, H085, Hershey, PA 17033, USA.
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