Genetic and functional linkage between ADAMTS superfamily proteins and fibrillin-1: a novel mechanism influencing microfibril assembly and function

Fibrillins constitute the major backbone of multifunctional microfibrils in elastic and nonelastic extracellular matrices. Proper assembly mechanisms are central to the formation and function of these microfibrils, and their properties are often compromised in pathological circumstances such as in Marfan syndrome and in other fibrillinopathies. Here, we have used human dermal fibroblasts to analyze the assembly of fibrillin-1 in dependence of other matrix-forming proteins. siRNA knockdown experiments demonstrated that the assembly of fibrillin-1 is strictly dependent on the presence of extracellular fibronectin fibrils. Immunolabeling performed at the light and electron microscopic level showed colocalization of fibrillin-1 with fibronectin fibrils at the early stages of the assembly process. Protein-binding assays demonstrated interactions of fibronectin with a C-terminal region of fibrillin-1, -2, and -3 and with an N-terminal region of fibrillin-1. The C-terminal half of fibrillin-2 and -3 had propensities to multimerize, as has been previously shown for fibrillin-1. The C-terminal of all three fibrillins interacted strongly with fibronectin as multimers, but not as monomers. Mapping studies revealed that the major binding interaction between fibrillins and fibronectin involves the collagen/gelatin-binding region between domains FNI6 and FNI9.

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Structure of the Fibrillin-1 N-Terminal Domains Suggests that Heparan Sulfate Regulates the Early Stages of Microfibril Assembly

Structure ◽

10.1016/j.str.2013.08.004 ◽

2013 ◽

Vol 21 (10) ◽

pp. 1743-1756 ◽

Cited By ~ 19

Author(s):

David A. Yadin ◽

Ian B. Robertson ◽

Joanne McNaught-Davis ◽

Paul Evans ◽

David Stoddart ◽

...

Keyword(s):

Heparan Sulfate ◽

Early Stages ◽

Microfibril Assembly ◽

Fibrillin 1 ◽

Terminal Domains

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Proteolysis of fibrillin-2 microfibrils is essential for normal skeletal development

10.1101/2021.02.03.429587 ◽

2021 ◽

Author(s):

Timothy J. Mead ◽

Daniel R. Martin ◽

Lauren W. Wang ◽

Stuart A. Cain ◽

Cagri Gulec ◽

...

Keyword(s):

Skeletal Development ◽

Postnatal Life ◽

Mrna Levels ◽

Skeletal Defects ◽

Microfibril Assembly ◽

Protease Substrate ◽

Fibrillin 1 ◽

Vitro Analysis ◽

In Vitro Analysis

AbstractThe extracellular matrix (ECM) undergoes an orchestrated transition from embryonic to mature ECM that is essential for postnatal life, yet the developmental transition mechanisms for ECM components and macromolecular complexes are poorly defined. Fibrillin microfibrils are macromolecular ECM complexes with important structural and regulatory roles. In mice, Fbn1 and Fbn2 mRNAs, which encode the major microfibrillar components, are strongly expressed during embryogenesis. Fbn2 mRNA levels rapidly decline postnatally, consistent with fibrillin-1 being the major component of adult tissue microfibrils. Here, by combining transgenic and N-terminomics strategies with in vitro analysis of microfibril assembly and intermolecular interactions, we identify cooperative proteolysis of fibrillin-2 by the secreted metalloproteases ADAMTS6 and ADAMTS10 as a mechanism contributing to postnatal fibrillin-1 dominance. The primacy of the protease-substrate relationship between ADAMTS6 and fibrillin-2 was unequivocally established by demonstrating a dramatic reversal of skeletal defects in Adamts6−/− embryos by Fbn2 haploinsufficiency.

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Mutant fibrillin-1 monomers lacking EGF-like domains disrupt microfibril assembly and cause severe marfan syndrome

Human Molecular Genetics ◽

10.1093/hmg/5.10.1581 ◽

1996 ◽

Vol 5 (10) ◽

pp. 1581-1587 ◽

Cited By ~ 66

Author(s):

W Liu

Keyword(s):

Marfan Syndrome ◽

Microfibril Assembly ◽

Fibrillin 1

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Functional analysis of zebrafish microfibril-associated glycoprotein-1 (Magp1) in vivo reveals roles for microfibrils in vascular development and function

Blood ◽

10.1182/blood-2005-02-0789 ◽

2006 ◽

Vol 107 (11) ◽

pp. 4364-4374 ◽

Cited By ~ 36

Author(s):

Eleanor Chen ◽

Jon D. Larson ◽

Stephen C. Ekker

Keyword(s):

Vascular Development ◽

Cardiovascular Tissue ◽

Protein Levels ◽

Wide Range ◽

Vessel Structure ◽

Fibrillin 1 ◽

Critical Requirement ◽

And Function ◽

Microfibril Formation

AbstractMutations in fibrillin-1 (FBN1) result in Marfan syndrome, demonstrating a critical requirement for microfibrils in vessel structure and function. However, the identity and function of many microfibril-associated molecules essential for vascular development and function have yet to be characterized. In our morpholino-based screen for members of the secretome required for vascular development, we identified a key player in microfibril formation in zebrafish embryogenesis. Microfibril-associated glycoprotein-1 (MAGP1) is a conserved protein found in mammalian and zebrafish microfibrils. Expression of magp1 mRNA is detected in microfibril-producing cells. Analysis of a functional Magp1-mRFP fusion protein reveals localization along the midline and in the vasculature during embryogenesis. Underexpression and overexpression analyses demonstrate that specific Magp1 protein levels are critical for vascular development. Integrin function is compromised in magp1 morphant embryos, suggesting that reduced integrin–matrix interaction is the main mechanism for the vascular defects in magp1 morphants. We further show that Magp1 and fibrillin-1 interact in vivo. This study implicates MAGP1 as a key player in microfibril formation and integrity during development. The essential role for MAGP1 in vascular morphogenesis and function also supports a wide range of clinical applications, including therapeutic targets in vascular disease and cardiovascular tissue engineering.

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