LTBP-2 competes with tropoelastin for binding to fibulin-5 and heparin, and is a negative modulator of elastinogenesis

LTBP-2 competes with tropoelastin for binding to fibulin-5 and heparin, and is a negative modulator of elastinogenesis

Latent transforming growth factor-beta-1 binding protein-2 (LTBP-2) is a protein of ill-defined function associated with elastic fibers during elastinogenesis. Although LTBP-2 binds fibrillin-1, fibulin-5, and heparin/heparan sulfate, molecules critical for normal elastic fiber assembly, it does not...

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Main Authors: Mohamed Sideek, Mohamed Arshad, Menz, Clementine, Parsi, Mahroo K., Gibson, Mark A.
Format: Article
Language:English
Published: Elsevier B.V 2013
Subjects:
RB Pathology
Online Access:http://irep.iium.edu.my/62192/
http://irep.iium.edu.my/62192/
http://irep.iium.edu.my/62192/
http://irep.iium.edu.my/62192/1/LTBP-2%20Elastin%20paper%20-%20Matrix%20Biology.pdf
id iium-62192
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spelling iium-621922018-02-25T05:06:21Z http://irep.iium.edu.my/62192/ LTBP-2 competes with tropoelastin for binding to fibulin-5 and heparin, and is a negative modulator of elastinogenesis Mohamed Sideek, Mohamed Arshad Menz, Clementine Parsi, Mahroo K. Gibson, Mark A. RB Pathology Latent transforming growth factor-beta-1 binding protein-2 (LTBP-2) is a protein of ill-defined function associated with elastic fibers during elastinogenesis. Although LTBP-2 binds fibrillin-1, fibulin-5, and heparin/heparan sulfate, molecules critical for normal elastic fiber assembly, it does not interact directly with elastin or its precursor, tropoelastin. We investigated the modulating effect of LTBP-2 on two key interactions of tropoelastin during elastinogenesis a) with fibulin-5 and b) with heparan sulfate (using heparin). Firstly, using solid phase assays we showed that LTBP-2 bound fibulin-5 (Kd = 26.47 ± 5.68 nM) with an affinity similar to that of the tropoelastin-fibulin-5 interaction (Kd= 24.66 ± 5.64 nM). Then using a competitive binding assay we showed that LTBP-2 inhibited the tropoelastin-fibulin-5 interaction in a dose dependent manner with almost complete inhibition obtained with 5-fold molar excess of LTBP-2. Interestingly, a fragment of LTBP-2 containing the fibulin-5 binding sequence only partially inhibited the tropoelasin-fibulin-5 interaction suggesting that LTBP-2 was directly blocking only the C-terminal tropoelastin binding site on fibulin-5 and indirectly blocking tropoelastin binding to the N-terminal region. In parallel experiments heparin was shown to have minor inhibitory effects on fibulin-5 interactions with tropoelastin and LTBP-2. However, LTBP-2 was shown to significantly inhibit the binding of heparin to tropoelastin with 50% inhibition achieved with 10 fold molar excess of LTBP-2. Confocal microscopy of fibroblast matrix showed strong co-distribution of LTBP-2 with fibulin-5 and fibrillin-1 and partial co-distribution with heparan sulfate proteoglycans, perlecan and syndecan-4. Also addition of exogenous LTBP-2 to ear cartilage chondrocyte cultures blocked elastinogenesis in a concentration-dependent manner. Overall the results indicate that LTBP-2 may have a negative regulatory role during elastic fiber assembly, perhaps in displacing elastin microassemblies from complexes with fibulin-5 and/or cell surface heparan sulfate proteoglycans. Elsevier B.V 2013-10-19 Article NonPeerReviewed application/pdf en http://irep.iium.edu.my/62192/1/LTBP-2%20Elastin%20paper%20-%20Matrix%20Biology.pdf Mohamed Sideek, Mohamed Arshad and Menz, Clementine and Parsi, Mahroo K. and Gibson, Mark A. (2013) LTBP-2 competes with tropoelastin for binding to fibulin-5 and heparin, and is a negative modulator of elastinogenesis. Matrix Biology, 34. pp. 114-123. ISSN 0945-053X https://ac.els-cdn.com/S0945053X13001364/1-s2.0-S0945053X13001364-main.pdf?_tid=spdf-2c68457b-e3ef-4363-91c6-5f682de6219e&acdnat=1519534042_5e02880ee8831bfb58b39415e61ab31b 10.1016/j.matbio.2013.10.007
repository_type Digital Repository
institution_category Local University
institution International Islamic University Malaysia
building IIUM Repository
collection Online Access
language English
topic RB Pathology
spellingShingle RB Pathology
Mohamed Sideek, Mohamed Arshad
Menz, Clementine
Parsi, Mahroo K.
Gibson, Mark A.
LTBP-2 competes with tropoelastin for binding to fibulin-5 and heparin, and is a negative modulator of elastinogenesis
description Latent transforming growth factor-beta-1 binding protein-2 (LTBP-2) is a protein of ill-defined function associated with elastic fibers during elastinogenesis. Although LTBP-2 binds fibrillin-1, fibulin-5, and heparin/heparan sulfate, molecules critical for normal elastic fiber assembly, it does not interact directly with elastin or its precursor, tropoelastin. We investigated the modulating effect of LTBP-2 on two key interactions of tropoelastin during elastinogenesis a) with fibulin-5 and b) with heparan sulfate (using heparin). Firstly, using solid phase assays we showed that LTBP-2 bound fibulin-5 (Kd = 26.47 ± 5.68 nM) with an affinity similar to that of the tropoelastin-fibulin-5 interaction (Kd= 24.66 ± 5.64 nM). Then using a competitive binding assay we showed that LTBP-2 inhibited the tropoelastin-fibulin-5 interaction in a dose dependent manner with almost complete inhibition obtained with 5-fold molar excess of LTBP-2. Interestingly, a fragment of LTBP-2 containing the fibulin-5 binding sequence only partially inhibited the tropoelasin-fibulin-5 interaction suggesting that LTBP-2 was directly blocking only the C-terminal tropoelastin binding site on fibulin-5 and indirectly blocking tropoelastin binding to the N-terminal region. In parallel experiments heparin was shown to have minor inhibitory effects on fibulin-5 interactions with tropoelastin and LTBP-2. However, LTBP-2 was shown to significantly inhibit the binding of heparin to tropoelastin with 50% inhibition achieved with 10 fold molar excess of LTBP-2. Confocal microscopy of fibroblast matrix showed strong co-distribution of LTBP-2 with fibulin-5 and fibrillin-1 and partial co-distribution with heparan sulfate proteoglycans, perlecan and syndecan-4. Also addition of exogenous LTBP-2 to ear cartilage chondrocyte cultures blocked elastinogenesis in a concentration-dependent manner. Overall the results indicate that LTBP-2 may have a negative regulatory role during elastic fiber assembly, perhaps in displacing elastin microassemblies from complexes with fibulin-5 and/or cell surface heparan sulfate proteoglycans.
format Article
author Mohamed Sideek, Mohamed Arshad
Menz, Clementine
Parsi, Mahroo K.
Gibson, Mark A.
author_facet Mohamed Sideek, Mohamed Arshad
Menz, Clementine
Parsi, Mahroo K.
Gibson, Mark A.
author_sort Mohamed Sideek, Mohamed Arshad
title LTBP-2 competes with tropoelastin for binding to fibulin-5 and heparin, and is a negative modulator of elastinogenesis
title_short LTBP-2 competes with tropoelastin for binding to fibulin-5 and heparin, and is a negative modulator of elastinogenesis
title_full LTBP-2 competes with tropoelastin for binding to fibulin-5 and heparin, and is a negative modulator of elastinogenesis
title_fullStr LTBP-2 competes with tropoelastin for binding to fibulin-5 and heparin, and is a negative modulator of elastinogenesis
title_full_unstemmed LTBP-2 competes with tropoelastin for binding to fibulin-5 and heparin, and is a negative modulator of elastinogenesis
title_sort ltbp-2 competes with tropoelastin for binding to fibulin-5 and heparin, and is a negative modulator of elastinogenesis
publisher Elsevier B.V
publishDate 2013
url http://irep.iium.edu.my/62192/
http://irep.iium.edu.my/62192/
http://irep.iium.edu.my/62192/
http://irep.iium.edu.my/62192/1/LTBP-2%20Elastin%20paper%20-%20Matrix%20Biology.pdf
first_indexed 2023-09-18T21:28:11Z
last_indexed 2023-09-18T21:28:11Z
_version_ 1777412332372099072

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