Fibulin-1 Acts as a Cofactor for the Matrix Metalloprotease ADAMTS-1

Abstract

ADAMTS-1 is a metalloprotease that has been implicated in the inhibition of angiogenesis and is a mediator of proteolytic cleavage of the hyaluronan binding proteoglycans, aggrecan and versican. In an attempt to further understand the biological function of ADAMTS-1, a yeast two-hybrid screen was performed using the carboxyl-terminal region of ADAMTS-1 as bait. As a result, the extracellular matrix protein fibulin-1 was identified as a potential interacting molecule. Through a series of analyses that included ligand affinity chromatography, co-immunoprecipitation, pulldown assays, and enzyme-linked immunosorbent assay, the ability of these two proteins to interact was substantiated. Additional studies showed that ADAMTS-1 and fibulin-1 colocalized in vivo. Furthermore, fibulin-1 was found to enhance the capacity of ADAMTS-1 to cleave aggrecan, a proteoglycan known to bind to fibulin-1. We confirmed that fibulin-1 was not a proteolytic substrate for ADAMTS-1. Together, these findings indicate that fibulin-1 is a new regulator of ADAMTS-1-mediated proteoglycan proteolysis and thus may play an important role in proteoglycan turnover in tissues where there is overlapping expression.Proteolytic events within the extracellular matrix (ECM) 3 are essential for developmental morphogenesis, homeostasis of adult tissues, and pathological conditions such as wound healing and tumor angiogenesis (1-3). ADAMTS-1 (a disintegrin-like and metalloprotease with thrombospondin type 1 motifs) belongs to a family of metalloproteases involved in the processing of ECM proteins such as procollagen types I and II (4, 5), von Willebrand factor (6 -8), and proteoglycans, including aggrecan, versican, and brevican (9 -12).A large percentage of mice that lack ADAMTS-1 die perinatally (45%), and those that survive display urinary track obstructions and kidney pathologies (13,14). In addition, most ADAMTS-1 null females are infertile because of abnormalities in the ovaries and endometrium (13). Evaluation of secondary follicles in the ovaries of ADAMTS-1 null mice revealed poor cumulus expansion and defective ovulation. These anomalies were attributed to incomplete versican proteolysis (15).Thus, a concrete understanding of the array of ADAMTS-1 biological functions will likely rely on insights from its substrates and regulation of catalytic function.The fibulins are a family of secreted glycoproteins that are components of elastic matrix fibers and basement membranes. Currently, there are six members of the fibulin family (16). The prototypic member, fibulin-1, contains the signature structural features of all fibulin family members, a series of epidermal growth factor-like repeats followed by a fibulin-type module at its carboxyl terminus (16).Functionally, fibulin-1 binds to many ECM proteins, including laminin, fibrinogen, fibronectin, nidogen-1, and endostatin, and to the proteoglycans, aggrecan and versican (17-22). Mice lacking fibulin-1 die perinatally and display vascular anomalies in the kidney in addition to extensive hemorrhage i...

Versican proteolysis mediates myocardial regression during outflow tract development

“…These findings suggest that proteolysis of versican may be involved in the remodeling of the cardiac outlet. In support of this possibility are the findings that the versican-cleaving proteinases AD-AMTS-1 and 9 (Jungers et al, 2005;Lee et al, 2005;Kern et al, 2006) as well as the ADAMTS cofactor fibulin-1 (Lee et al, 2005), are expressed in the heart coincident with the events of OFT remodeling. In addition to the ADAMTS family of MMPs, MMP-2 is also highly expressed in the OFT (Alexander et al, 1997;Cai et al, 2000;Ratajska and Cleutjens, 2002) and has been shown to degrade versican (Perides et al, 1995;Passi et al, 1999).…”

The secreted AdamTS-A metalloprotease is required for collective cell migration

“…7). This idea is consistent with studies of mammalian ADAMTS proteins and worm GON-1, where both known and suspected substrates are secreted proteins: aggrecan, brevican, versican and procollagen for mammalian ADAMTS family members, and Collagen IV and/or Fibulin for GON-1 (RodriguezManzaneque et al, 2002;Sandy et al, 2001;Zheng et al, 2001;Kubota et al, 2004;Lee et al, 2005;McCulloch et al, 2009;Enomoto et al, 2010). Indeed, it appears that it is the closely related ADAM proteases that localize and function at the plasma membrane, and specialize in cleaving transmembrane proteins, including members of the cadherin and protocadherin family.…”

“…Indeed, a single mammalian ADAMTS can cleave a variety of targets. For example, ADAMTS 1 cleaves aggrecan, versican or procollagen 1 in a tissue-specific manner (Rodriguez-Manzaneque et al, 2002;Sandy et al, 2001;Lee et al, 2005). Different mammalian ADAMTSs can also cleave the same target protein; ADAMTS 1, ADAMTS 4, ADAMTS 5, ADAMTS 9 and ADAMTS 20 have all been shown to cleave versican in different developmental contexts (Sandy et al, 2001;McCulloch et al, 2009;Enomoto et al, 2010).…”

Fibulin-1 Binds to Fibroblast Growth Factor 8 with High Affinity

“…In the second report mutations in the glycosyltranferase enzyme Ext1 result in outflow tract defects that can be reversed using FGF8 (35). It is interesting to speculate that proteoglycans, FBLN1, which is involved proteoglycan processing (9,36), and FGF8 all play a cooperative role in the maintenance and guidance of NCC to ensure proper cell migration and population in the second heart field and outflow tract for proper development.…”