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Șulea CM, Mártonfalvi Z, Csányi C, Haluszka D, Pólos M, Ágg B, Stengl R, Benke K, Szabolcs Z, Kellermayer MSZ. Nanoscale Structural Comparison of Fibrillin-1 Microfibrils Isolated from Marfan and Non-Marfan Syndrome Human Aorta. Int J Mol Sci 2023; 24:ijms24087561. [PMID: 37108724 PMCID: PMC10145871 DOI: 10.3390/ijms24087561] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Revised: 04/18/2023] [Accepted: 04/18/2023] [Indexed: 04/29/2023] Open
Abstract
Fibrillin-1 microfibrils are essential elements of the extracellular matrix serving as a scaffold for the deposition of elastin and endowing connective tissues with tensile strength and elasticity. Mutations in the fibrillin-1 gene (FBN1) are linked to Marfan syndrome (MFS), a systemic connective tissue disorder that, besides other heterogeneous symptoms, usually manifests in life-threatening aortic complications. The aortic involvement may be explained by a dysregulation of microfibrillar function and, conceivably, alterations in the microfibrils' supramolecular structure. Here, we present a nanoscale structural characterization of fibrillin-1 microfibrils isolated from two human aortic samples with different FBN1 gene mutations by using atomic force microscopy, and their comparison with microfibrillar assemblies purified from four non-MFS human aortic samples. Fibrillin-1 microfibrils displayed a characteristic "beads-on-a-string" appearance. The microfibrillar assemblies were investigated for bead geometry (height, length, and width), interbead region height, and periodicity. MFS fibrillin-1 microfibrils had a slightly higher mean bead height, but the bead length and width, as well as the interbead height, were significantly smaller in the MFS group. The mean periodicity varied around 50-52 nm among samples. The data suggest an overall thinner and presumably more frail structure for the MFS fibrillin-1 microfibrils, which may play a role in the development of MFS-related aortic symptomatology.
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Affiliation(s)
- Cristina M Șulea
- Department of Biophysics and Radiation Biology, Semmelweis University, 1094 Budapest, Hungary
- Heart and Vascular Center, Semmelweis University, 1122 Budapest, Hungary
- Hungarian Marfan Foundation, 1122 Budapest, Hungary
| | - Zsolt Mártonfalvi
- Department of Biophysics and Radiation Biology, Semmelweis University, 1094 Budapest, Hungary
| | - Csilla Csányi
- Department of Biophysics and Radiation Biology, Semmelweis University, 1094 Budapest, Hungary
| | - Dóra Haluszka
- Department of Biophysics and Radiation Biology, Semmelweis University, 1094 Budapest, Hungary
| | - Miklós Pólos
- Heart and Vascular Center, Semmelweis University, 1122 Budapest, Hungary
- Hungarian Marfan Foundation, 1122 Budapest, Hungary
| | - Bence Ágg
- Heart and Vascular Center, Semmelweis University, 1122 Budapest, Hungary
- Hungarian Marfan Foundation, 1122 Budapest, Hungary
- Department of Pharmacology and Pharmacotherapy, Semmelweis University, 1089 Budapest, Hungary
| | - Roland Stengl
- Heart and Vascular Center, Semmelweis University, 1122 Budapest, Hungary
- Hungarian Marfan Foundation, 1122 Budapest, Hungary
| | - Kálmán Benke
- Heart and Vascular Center, Semmelweis University, 1122 Budapest, Hungary
- Hungarian Marfan Foundation, 1122 Budapest, Hungary
- Department of Cardiac Surgery, University Hospital Halle (Saale), 06120 Halle (Saale), Germany
| | - Zoltán Szabolcs
- Heart and Vascular Center, Semmelweis University, 1122 Budapest, Hungary
- Hungarian Marfan Foundation, 1122 Budapest, Hungary
| | - Miklós S Z Kellermayer
- Department of Biophysics and Radiation Biology, Semmelweis University, 1094 Budapest, Hungary
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2
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Overwater E, Marsili L, Baars MJH, Baas AF, van de Beek I, Dulfer E, van Hagen JM, Hilhorst-Hofstee Y, Kempers M, Krapels IP, Menke LA, Verhagen JMA, Yeung KK, Zwijnenburg PJG, Groenink M, van Rijn P, Weiss MM, Voorhoeve E, van Tintelen JP, Houweling AC, Maugeri A. Results of next-generation sequencing gene panel diagnostics including copy-number variation analysis in 810 patients suspected of heritable thoracic aortic disorders. Hum Mutat 2018; 39:1173-1192. [PMID: 29907982 PMCID: PMC6175145 DOI: 10.1002/humu.23565] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2017] [Revised: 05/23/2018] [Accepted: 05/30/2018] [Indexed: 01/02/2023]
Abstract
Simultaneous analysis of multiple genes using next-generation sequencing (NGS) technology has become widely available. Copy-number variations (CNVs) in disease-associated genes have emerged as a cause for several hereditary disorders. CNVs are, however, not routinely detected using NGS analysis. The aim of this study was to assess the diagnostic yield and the prevalence of CNVs using our panel of Hereditary Thoracic Aortic Disease (H-TAD)-associated genes. Eight hundred ten patients suspected of H-TAD were analyzed by targeted NGS analysis of 21 H-TAD associated genes. In addition, the eXome hidden Markov model (XHMM; an algorithm to identify CNVs in targeted NGS data) was used to detect CNVs in these genes. A pathogenic or likely pathogenic variant was found in 66 of 810 patients (8.1%). Of these 66 pathogenic or likely pathogenic variants, six (9.1%) were CNVs not detectable by routine NGS analysis. These CNVs were four intragenic (multi-)exon deletions in MYLK, TGFB2, SMAD3, and PRKG1, respectively. In addition, a large duplication including NOTCH1 and a large deletion encompassing SCARF2 were detected. As confirmed by additional analyses, both CNVs indicated larger chromosomal abnormalities, which could explain the phenotype in both patients. Given the clinical relevance of the identification of a genetic cause, CNV analysis using a method such as XHMM should be incorporated into the clinical diagnostic care for H-TAD patients.
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Affiliation(s)
- Eline Overwater
- Department of Clinical Genetics, VU University Medical Center, Amsterdam, the Netherlands.,Department of Clinical Genetics, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands
| | - Luisa Marsili
- Department of Clinical Genetics, VU University Medical Center, Amsterdam, the Netherlands.,Medical Genetics Unit, Tor Vergata University Hospital, Rome, Italy
| | - Marieke J H Baars
- Department of Clinical Genetics, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands
| | - Annette F Baas
- Department of Medical Genetics, University Medical Center Utrecht, Utrecht, the Netherlands
| | - Irma van de Beek
- Department of Clinical Genetics, VU University Medical Center, Amsterdam, the Netherlands.,Department of Clinical Genetics, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands
| | - Eelco Dulfer
- Department of Genetics, University Medical Center Groningen, Groningen, the Netherlands
| | - Johanna M van Hagen
- Department of Clinical Genetics, VU University Medical Center, Amsterdam, the Netherlands
| | | | - Marlies Kempers
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Ingrid P Krapels
- Department of Clinical Genetics, Maastricht University Medical Center, Maastricht, the Netherlands
| | - Leonie A Menke
- Department of Pediatrics, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands
| | - Judith M A Verhagen
- Department of Clinical Genetics, Erasmus University Medical Center, Rotterdam, the Netherlands
| | - Kak K Yeung
- Department of Surgery, Institute for Cardiovascular Research, VU University Medical Center, Amsterdam, the Netherlands.,Department of Physiology, Institute for Cardiovascular Research, VU University Medical Center, Amsterdam, the Netherlands
| | - Petra J G Zwijnenburg
- Department of Clinical Genetics, VU University Medical Center, Amsterdam, the Netherlands
| | - Maarten Groenink
- Department of Cardiology and Radiology, Academic Medical Center Amsterdam, University of Amsterdam, Amsterdam, the Netherlands
| | - Peter van Rijn
- Department of Clinical Genetics, VU University Medical Center, Amsterdam, the Netherlands
| | - Marjan M Weiss
- Department of Clinical Genetics, VU University Medical Center, Amsterdam, the Netherlands
| | - Els Voorhoeve
- Department of Clinical Genetics, VU University Medical Center, Amsterdam, the Netherlands
| | - J Peter van Tintelen
- Department of Clinical Genetics, VU University Medical Center, Amsterdam, the Netherlands.,Department of Clinical Genetics, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands
| | - Arjan C Houweling
- Department of Clinical Genetics, VU University Medical Center, Amsterdam, the Netherlands
| | - Alessandra Maugeri
- Department of Clinical Genetics, VU University Medical Center, Amsterdam, the Netherlands
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3
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Localized micro- and nano-scale remodelling in the diabetic aorta. Acta Biomater 2014; 10:4843-4851. [PMID: 25014552 PMCID: PMC4199142 DOI: 10.1016/j.actbio.2014.07.001] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2014] [Revised: 05/22/2014] [Accepted: 07/01/2014] [Indexed: 11/20/2022]
Abstract
Diabetes is strongly associated with cardiovascular disease, but the mechanisms, structural and biomechanical consequences of aberrant blood vessel remodelling remain poorly defined. Using an experimental (streptozotocin, STZ) rat model of diabetes, we hypothesized that diabetes enhances extracellular protease activity in the aorta and induces morphological, compositional and localized micromechanical tissue remodelling. We found that the medial aortic layer underwent significant thickening in diabetic animals but without significant changes in collagen or elastin (abundance). Scanning acoustic microscopy demonstrated that such tissue remodelling was associated with a significant decrease in acoustic wave speed (an indicator of reduced material stiffness) in the inter-lamellar spaces of the vessel wall. This index of decreased stiffness was also linked to increased extracellular protease activity (assessed by semi-quantitative in situ gelatin zymography). Such a proteolytically active environment may affect the macromolecular structure of long-lived extracellular matrix molecules. To test this hypothesis, we also characterized the effects of diabetes on the ultrastructure of an important elastic fibre component: the fibrillin microfibril. Using size exclusion chromatography and atomic force microscopy, we isolated and imaged microfibrils from both healthy and diabetic aortas. Microfibrils derived from diabetic tissues were fragmented, morphologically disrupted and weakened (as assessed following molecular combing). These structural and functional abnormalities were not replicated by in vitro glycation. Our data suggest that proteolysis may be a key driver of localized mechanical change in the inter-lamellar space of diabetic rat aortas and that structural proteins (such as fibrillin microfbrils) may be biomarkers of diabetes induced damage.
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4
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Franken R, Heesterbeek TJ, de Waard V, Zwinderman AH, Pals G, Mulder BJM, Groenink M. Diagnosis and genetics of Marfan syndrome. Expert Opin Orphan Drugs 2014. [DOI: 10.1517/21678707.2014.950223] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
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5
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Charbonneau NL, Jordan CD, Keene DR, Lee-Arteaga S, Dietz HC, Rifkin DB, Ramirez F, Sakai LY. Microfibril structure masks fibrillin-2 in postnatal tissues. J Biol Chem 2010; 285:20242-51. [PMID: 20404337 DOI: 10.1074/jbc.m109.087031] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Fibrillin microfibrils are polymeric structures present in connective tissues. The importance of fibrillin microfibrils to connective tissue function has been demonstrated by the multiple genetic disorders caused by mutations in fibrillins and in microfibril-associated molecules. However, knowledge of microfibril structure is limited, largely due to their insolubility. Most previous studies have focused on how fibrillin-1 is organized within microfibril polymers. In this study, an immunochemical approach was used to circumvent the insolubility of microfibrils to determine the role of fibrillin-2 in postnatal microfibril structure. Results obtained from studies of wild type and fibrillin-1 null tissues, using monoclonal and polyclonal antibodies with defined epitopes, demonstrated that N-terminal fibrillin-2 epitopes are masked in postnatal microfibrils and can be revealed by enzymatic digestion or by genetic ablation of Fbn1. From these studies, we conclude that fetal fibrillin polymers form an inner core within postnatal microfibrils and that microfibril structure evolves as growth and development proceed into the postnatal period. Furthermore, documentation of a novel cryptic site present in EGF4 in fibrillin-1 underscores the molecular complexity and tissue-specific differences in microfibril structure.
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Affiliation(s)
- Noe L Charbonneau
- Shriners Hospital for Children, 3101 SW Sam Jackson Park Rd., Portland, OR 97239, USA
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6
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Kuo CL, Isogai Z, Keene DR, Hazeki N, Ono RN, Sengle G, Bächinger HP, Sakai LY. Effects of fibrillin-1 degradation on microfibril ultrastructure. J Biol Chem 2006; 282:4007-20. [PMID: 17158461 DOI: 10.1074/jbc.m606370200] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Current models of the elastic properties and structural organization of fibrillin-containing microfibrils are based primarily on microscopic analyses of microfibrils liberated from connective tissues after digestion with crude collagenase. Results presented here demonstrate that this digestion resulted in the cleavage of fibrillin-1 and loss of specific immunoreactive epitopes. The proline-rich region and regions near the second 8-cysteine domain in fibrillin-1 were easily cleaved by crude collagenase. Other sites that may also be cleaved during microfibril digestion and extraction were identified. In contrast to collagenase-digested microfibrils, guanidine-extracted microfibrils contained all fibrillin-1 epitopes recognized by available antibodies. The ultrastructure of guanidine-extracted microfibrils differed markedly from that of collagenase-digested microfibrils. Fibrillin-1 filaments splayed out, extending beyond the width of the periodic globular beads. Both guanidine-extracted and collagenase-digested microfibrils were subjected to extensive digestion by crude collagenase. Collagenase digestion of guanidine-extracted microfibrils removed the outer filaments, revealing a core structure. In contrast to microfibrils extracted from tissues, cell culture microfibrils could be digested into short units containing just a few beads. These data suggest that additional cross-links stabilize the long beaded microfibrils in tissues. Based on the microfibril morphologies observed after these experiments, on the crude collagenase cleavage sites identified in fibrillin-1, and on known antibody binding sites in fibrillin-1, a model is proposed in which fibrillin-1 molecules are staggered in microfibrils. This model further suggests that the N-terminal half of fibrillin-1 is asymmetrically exposed in the outer filaments, whereas the C-terminal half of fibrillin-1 is present in the interior of the microfibril.
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Affiliation(s)
- Chiu-Liang Kuo
- Department of Biochemistry and Molecular Biology, Oregon Health and Science University, Portland, Oregon 97239, USA
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7
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Marfan Syndrome-causing Mutations in Fibrillin-1 Result in Gross Morphological Alterations and Highlight the Structural Importance of the Second Hybrid Domain. J Biol Chem 2006. [DOI: 10.1016/s0021-9258(19)84100-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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8
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Mellody KT, Freeman LJ, Baldock C, Jowitt TA, Siegler V, Raynal BDE, Cain SA, Wess TJ, Shuttleworth CA, Kielty CM. Marfan syndrome-causing mutations in fibrillin-1 result in gross morphological alterations and highlight the structural importance of the second hybrid domain. J Biol Chem 2006; 281:31854-62. [PMID: 16905551 DOI: 10.1074/jbc.m602743200] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mutations in fibrillin-1 result in Marfan syndrome, which affects the cardiovascular, skeletal and ocular systems. The multiorgan involvement and wide spectrum of associated phenotypes highlights the complex pathogenesis underlying Marfan syndrome. To elucidate the genotype to phenotype correlations, we engineered four Marfan syndrome causing mutations into a fibrillin-1 fragment encoded by exons 18-25, a region known to interact with tropoelastin. Biophysical and biochemical approaches, including small angle x-ray scattering, analytical ultracentrifugation, and circular dichroism, were used to study the impact of these mutations upon the structure and function of the protein. Mutations G880S, C862R, and C908R, situated within the second hybrid domain, disrupted the ratio of alpha-helix to beta-sheet leading to a more compact conformation. These data clearly demonstrate the importance of the previously uncharacterized hybrid domain in fibrillin-1 structure. In contrast, mutation K1023N situated within the linker region between the third eight cysteine motif and cbEGF 11 markedly extended the length of the fragment. However, none of the mutations affected tropoelastin binding. The profound effects of all four mutations on fragment conformation suggest that they contribute to the pathogenesis of Marfan syndrome by disrupting protein folding and its assembly into fibrillin-rich microfibrils.
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Affiliation(s)
- Kieran T Mellody
- Wellcome Trust Centre for Cell-Matrix Research, Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, United Kingdom
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9
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Collod-Béroud G, Le Bourdelles S, Ades L, Ala-Kokko L, Booms P, Boxer M, Child A, Comeglio P, De Paepe A, Hyland JC, Holman K, Kaitila I, Loeys B, Matyas G, Nuytinck L, Peltonen L, Rantamaki T, Robinson P, Steinmann B, Junien C, Béroud C, Boileau C. Update of the UMD-FBN1 mutation database and creation of an FBN1 polymorphism database. Hum Mutat 2003; 22:199-208. [PMID: 12938084 DOI: 10.1002/humu.10249] [Citation(s) in RCA: 223] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Fibrillin is the major component of extracellular microfibrils. Mutations in the fibrillin gene on chromosome 15 (FBN1) were first described in the heritable connective disorder, Marfan syndrome (MFS). FBN1 has also been shown to harbor mutations related to a spectrum of conditions phenotypically related to MFS, called "type-1 fibrillinopathies." In 1995, in an effort to standardize the information regarding these mutations and to facilitate their mutational analysis and identification of structure/function and phenotype/genotype relationships, we created a human FBN1 mutation database, UMD-FBN1. This database gives access to a software package that provides specific routines and optimized multicriteria research and sorting tools. For each mutation, information is provided at the gene, protein, and clinical levels. This tool is now a worldwide reference and is frequently used by teams working in the field; more than 220,000 interrogations have been made to it since January 1998. The database has recently been modified to follow the guidelines on mutation databases of the HUGO Mutation Database Initiative (MDI) and the Human Genome Variation Society (HGVS), including their approved mutation nomenclature. The current update shows 559 entries, of which 421 are novel. UMD-FBN1 is accessible at www.umd.be/. We have also recently developed a FBN1 polymorphism database in order to facilitate diagnostics.
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10
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Kettle S, Card CM, Hutchinson S, Sykes B, Handford PA. Characterisation of fibrillin-1 cDNA clones in a human fibroblast cell line that assembles microfibrils. Int J Biochem Cell Biol 2000; 32:201-14. [PMID: 10687954 DOI: 10.1016/s1357-2725(99)00120-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Abstract
Fibrillin-1 is a large extracellular glycoprotein which is a major structural component of 10-12 nm microfibrils. Defects in human fibrillin-1 give rise to the autosomal dominant connective tissue disease the Marfan syndrome and related disorders. Previous studies examining the biosynthesis and secretion of recombinant fibrillin-1 fragments have been performed in cell lines which do not assemble fibrillin into extracellular 10-12 nm microfibrils. Conflicting data have been obtained regarding N-terminal processing. In this study we have characterised a human fibroblast cell line MSU-1.1 which shows a similar endogenous fibrillin-1 pulse chase profile to primary human dermal fibroblasts and produces microfibrils. Expression of a approximately 50 kDa N-terminal recombinant peptide in MSU-1.1 resulted in efficient secretion of this peptide into conditioned media, N-terminal sequence analysis of the purified peptide identified 2 protease cleavage sites and a presumed signal peptidase site. Together these data identify the natural leader sequence of fibrillin-1 and the presence of two processing sites in the N-terminus of fibrillin-1. The identification of an N-terminal processing site in recombinant fibrillin-1 similar to that obtained in a previous study which used an HT1080 fibrosarcoma host cell line excludes defective N-terminal processing as the cause of the assembly defect in this cell line. A full length normal and mutant fibrillin cDNA (approximately 8.6 kb) was constructed and stable integration of each into MSU1.1 led to RNA transcription at approximately 5% of endogenous levels. This is the first report of transcription from the full length fibrillin-1 cDNA. The low levels of transcription achieved, suggest that additional upstream and downstream DNA sequence elements will be required for high levels of full length fibrillin-1 cDNA expression.
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Affiliation(s)
- S Kettle
- Department of Biochemistry, Oxford, UK
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11
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Nunes I, Gleizes PE, Metz CN, Rifkin DB. Latent transforming growth factor-beta binding protein domains involved in activation and transglutaminase-dependent cross-linking of latent transforming growth factor-beta. J Cell Biol 1997; 136:1151-63. [PMID: 9060478 PMCID: PMC2132473 DOI: 10.1083/jcb.136.5.1151] [Citation(s) in RCA: 286] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/1996] [Revised: 12/12/1996] [Indexed: 02/03/2023] Open
Abstract
Transforming growth factor-beta (TGF-beta) is secreted by many cell types as part of a large latent complex composed of three subunits: TGF-beta, the TGF-beta propeptide, and the latent TGF-beta binding protein (LTBP). To interact with its cell surface receptors, TGF-beta must be released from the latent complex by disrupting noncovalent interactions between mature TGF-beta and its propeptide. Previously, we identified LTBP-1 and transglutaminase, a cross-linking enzyme, as reactants involved in the formation of TGF-beta. In this study, we demonstrate that LTBP-1 and large latent complex are substrates for transglutaminase. Furthermore, we show that the covalent association between LTBP-1 and the extracellular matrix is transglutaminase dependent, as little LTBP-1 is recovered from matrix digests prepared from cultures treated with transglutaminase inhibitors. Three polyclonal antisera to glutathione S-transferase fusion proteins containing amino, middle, or carboxyl regions of LTBP-1S were used to identify domains of LTBP-1 involved in cross-linking and formation of TGF-beta by transglutaminase. Antibodies to the amino and carboxyl regions of LTBP-1S abrogate TGF-beta generation by vascular cell cocultures or macrophages. However, only antibodies to the amino-terminal region of LTBP-1 block transglutaminase-dependent cross-linking of large latent complex or LTBP-1. To further identify transglutaminase-reactive domains within the amino-terminal region of LTBP-1S, mutants of LTBP-1S with deletions of either the amino-terminal 293 (deltaN293) or 441 (deltaN441) amino acids were expressed transiently in CHO cells. Analysis of the LTBP-1S content in matrices of transfected CHO cultures revealed that deltaN293 LTBP-1S was matrix associated via a transglutaminase-dependent reaction, whereas deltaN441 LTBP-1S was not. This suggests that residues 294-441 are critical to the transglutaminase reactivity of LTBP-1S.
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Affiliation(s)
- I Nunes
- Department of Cell Biology, Kaplan Cancer Center, New York University Medical Center, New York 10016, USA
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12
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Abstract
A casual association has been established between mutations in the fibrillin 1 gene and Marfan syndrome and related phenotypes. Analysis of mutations in these disease types has provided new insights into microfibril assembly and function. These include evidence for a mutation in a fibrillin 1 domain associated with severe phenotype; indication of profibrillin processing by a furin-like endoprotease; linkage between extracellular processing and fibrillin 1 polymerization; and involvement of calcium binding in monomer stabilization and microfibril assembly. Identification of intragenic DNA polymorphisms and determination of intron/exon junction sequences have significantly improved our ability to diagnose Marfan syndrome and to detect fibrillin 1 mutations. Additional work has provided strong evidence for structural and functional heterogeneity of microfibrillin. The evidence includes the identification of fibrillin 2, a microfibrillar component structurally related to fibrillin 1; the differential pattern of gene expression of the two fibrillin; and the association of fibrillin 2 mutations with congenital contractural arachnodactyly.
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Affiliation(s)
- F Ramirez
- Brookdale Center for Molecular Biology, Mount Sinai School of Medicine, New York, New York 10029, USA.
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13
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Karttunen L, Lönnqvist L, Godfrey M, Peltonen L, Syvänen AC. An accurate method for comparing transcript levels of two alleles or highly homologous genes: application to fibrillin transcripts in Marfan patients' fibroblasts. Genome Res 1996; 6:392-403. [PMID: 8743989 DOI: 10.1101/gr.6.5.392] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
We introduce here a novel and generally applicable, solid-phase minisequencing-based approach for rapid estimation of relative levels of transcripts with high sequence homology. This study was undertaken to screen for the consequences of different fibrillin-1 mutations on the transcript levels in patients with the Marfan syndrome (MFS). This dominantly inherited, connective tissue disorder is characterized by pleiotrophic symptoms in cardiovascular, skeletal, and ocular systems. A spectrum of disease mutations in the gene encoding fibrillin-1 (FBN1), a glycoprotein component of extracellular matrix microfibrils, has been identified in MFS patients, but the mechanisms by which mutations result in different phenotypic manifestations are still unknown to a large extent. Our data from the quantitation of FBN1 transcripts provide support for the hypothesis that mutations causing premature stop codons result in a milder phenotype than classical MFS by reducing the stability of the mutant transcript and, consequently, decreasing the interference of mutant polypeptide in the formation of fibrillin fibers. We also applied this mRNA quantitation method to determine the relative ratio between transcripts from the genes coding for two highly homologous microfibrillar components, FBN1 and FBN2, in control fibroblast cultures as well as in fibroblasts from MFS patients. Interestingly, these data show large variations between the levels of the two transcripts in fibroblast cultures, but these variations do not correlate either with the nature of the disease mutation or to the clinical MFS phenotype.
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Affiliation(s)
- L Karttunen
- Department of Human Molecular Genetics, National Public Health Institute, Helsinki, Finland
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14
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Siracusa LD, McGrath R, Ma Q, Moskow JJ, Manne J, Christner PJ, Buchberg AM, Jimenez SA. A tandem duplication within the fibrillin 1 gene is associated with the mouse tight skin mutation. Genome Res 1996; 6:300-13. [PMID: 8723723 DOI: 10.1101/gr.6.4.300] [Citation(s) in RCA: 212] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Mice carrying the Tight skin (Tsk) mutation have thickened skin and visceral fibrosis resulting from an accumulation of extracellular matrix molecules. These and other connective tissue abnormalities have made Tskl + mice models for scleroderma, hereditary emphysema, and myocardial hypertrophy. Previously we localized Tsk to mouse chromosome 2 in a region syntenic with human chromosome 15. The microfibrillar glycoprotein gene, fibrillin 1 (FBN1), on human chromosome 15q, provided a candidate for the Tsk mutation. We now demonstrate that the Tsk chromosome harbors a 30- to 40-kb genomic duplication within the Fbn1 gene that results in a larger than normal in-frame Fbn1 transcript. These findings provide hypotheses to explain some of the phenotypic characteristics of Tskl + mice and the lethality of Tsk/Tsk embryos.
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Affiliation(s)
- L D Siracusa
- Department of Microbiology and Immunology, Jefferson Cancer Center, Thomas Jefferson University, Philadelphia, Pennsylvania 19107-5541, USA.
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15
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Kielty CM, Shuttleworth CA. Fibrillin-containing microfibrils: structure and function in health and disease. Int J Biochem Cell Biol 1995; 27:747-60. [PMID: 7584608 DOI: 10.1016/1357-2725(95)00028-n] [Citation(s) in RCA: 82] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Fibrillin-containing microfibrils are a unique class of connective tissue macromolecules whose critical contribution to the establishment and maintenance of diverse extracellular matrices was underlined by the recent linkage of their principal structural component fibrillin to Marfan syndrome, a heritable disorder with pleiotrophic connective tissue manifestations. The complexity of the structure: function relationships of these macromolecules was highlighted by the recent elucidation of the primary structure of fibrillin and characterisation of fibrillin mutations in Marfan patients. This review examines current understanding of the expression and assembly of fibrillin and describes new approaches which are now being applied to elucidate the many outstanding structural, organisational and functional aspects of the fibrillin-containing microfibrils.
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Affiliation(s)
- C M Kielty
- School of Biological Sciences, University of Manchester, U.K
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