Proteolytic cleavage of versican during cardiac cushion morphogenesis

Abstract

The proteoglycan versican is essential to the formation of endocardial cushion mesenchyme by epithelial-mesenchymal transformation (EMT). A potentially important factor in the regulation of versican activity during cushion EMT is proteolysis by ADAMTS metalloproteinases. Using antibodies to the DPEAAE neoepitope created by ADAMTS proteolysis of versican, we detected the amino terminal 70-kDa versican cleavage fragment in cardiac cushions. Initially (i.e., 9.5 days post coitum [dpc]), the fragment is associated with endocardial cells undergoing EMT and with newly derived mesenchymal cells. ADAMTS-1 and its cofactor fibulin-1 were also associated with these cells. As cushions become increasingly populated with mesenchymal cells (10.5-12.5 dpc), the fragment remains asymmetrically distributed compared with the pattern of total versican. Highest levels of the fragment are present in regions immediately subjacent to the endocardium characterized as having densely packed, rounded cells, lacking cellular protrusions. With further development (i.e., 12.5-14.5 dpc), the pattern of fragment distribution within cushions broadens to include the ECM surrounding loosely packed mesenchymal cells in the cushion core. Together, the findings reveal that versican proteolysis leading to the production of the 70-kDa fragment is integral to the formation and differentiation of endocardial cushion mesenchyme.

The role of versican isoforms V0/V1 in glioma migration mediated by transforming growth factor-β2

“…We detected high molecular mass intact versican V1 at around 300 kDa, which is the expected molecular mass of V1 without chondroitinase digestion in glioma cell lines (Dours-Zimmermann and Zimmermann, 1994) verifying that the antibody reacts with the DPEAAE sequence in intact versican V1 (Figure 2A). The products migrating around 75 and 50 kDa represent the G1-DPEAAE-cleaved products of human versican V1 by ADAMTS-1 and ADAMTS-4 as described before with the same antibody (Sandy et al, 2001;Russell et al, 2003;Somerville et al, 2003;Kern et al, 2006). These signals representing intact versican V1 and its cleavage products were upregulated with exogenous TGF-b2 in a concentration-dependent manner.…”

“…As the antibody does not react with the DPEAAE sequence when it is present in intact versican (V0) (Sandy et al, 2001;Kern et al, 2007), no high molecular mass band representing intact versican (V0), which migrates at 350 -400 kDa (data not shown), could be detected in low-density gels (4%) and after chondroitinase ABC digestion. However, V1, which runs around 280 kDa, could be detected with high versican V1 concentrations (Russell et al, 2003;Kern et al, 2006).…”

Emerging roles of ADAM and ADAMTS metalloproteinases in cancer

“…In bold are ADAMs expressed in mouse but not in human. ADAM and ADAMTS molecules have also been implicated in several pathologies [16,[43][44][45]. ADAMTS-13 deficiency is responsible for thrombotic thrombocytopenic purpura characterized by the formation of microvascular von Willebrand Factor (vWF) and platelet-rich thrombi, associated with anaemia, renal failure and neurological dysfunction [46].…”

Versican proteolysis mediates myocardial regression during outflow tract development

“…All four versican variants V 0 , V 1 , V 2 , and V 3 are present throughout cardiac development Zako et al, 1995;Kern et al, 2006). Although these variants contain a combination of functional domains, all contain both an N-terminal G1 domain, which binds hyaluronan (HA; Margolis and Margolis, 1994), and a C-terminal G3 domain, which interacts with other extracellular matrix molecules (Zhang et al, 1998;Day et al, 2004;Wu et al, 2005).…”