Embryonic development is an exceptionally dynamic process, requiring a provisional extracellular matrix that is amenable to rapid remodeling, and proteolytic or non-proteolytic mechanisms that can remodel the major components of this matrix. Versican is a chondroitin-sulfate proteoglycan that forms highly hydrated complexes with hyaluronan and is widely distributed in the provisional matrix of mammalian embryos. It has been extensively studied in the context of cardiovascular morphogenesis, neural crest cell migration and skeletal development. Analysis of Vcan transgenic mice has established the requirement for versican in cardiac development and its role in skeletogenesis. The ADAMTS family includes several versican-degrading proteases that are active during remodeling of the embryonic provisional matrix, especially during sculpting of versican-rich tissues. Versican is cleaved at specific peptide bonds by ADAMTS proteases, and the cleavage products are detectable by neo-epitope antibodies. Myocardial compaction, closure of the secondary palate (in which neural crest derived cells participate), endocardial cushion remodeling, myogenesis and interdigital web regression are developmental contexts in which ADAMTS-mediated versican proteolysis has been identified as a crucial requirement. ADAMTS proteases are expressed coordinately and function cooperatively in many of these contexts. In addition to versican clearance, ADAMTS proteases generate a bioactive versican fragment containing the N-terminal G1 domain, which we have named versikine. This review promotes the view that the embryonic extracellular matrix has evolved not only to provide a permissive environment for embryo growth and morphogenesis, but through its dissolution to influence and regulate cellular processes.

• Interplay between myeloma niche stromal cells and myeloid cells generates versikine, a novel damageassociated molecular pattern.• Versikine may promote antigen-presenting cell maturation and CD8 1 T-cell activation/recruitment to the tumor bed.Myeloma immunosurveillance remains incompletely understood. We have demonstrated proteolytic processing of the matrix proteoglycan, versican (VCAN), in myeloma tumors. Whereas intact VCAN exerts tolerogenic activities through Toll-like receptor 2 (TLR2) binding, the immunoregulatory consequences of VCAN proteolysis remain unknown. Here we show that human myeloma tumors displaying CD81 infiltration/aggregates underwent VCAN proteolysis at a site predicted to generate a glycosaminoglycan-bereft N-terminal fragment, versikine. Myeloma-associated macrophages (MAMs), rather than tumor cells, chiefly produced V1-VCAN, the precursor to versikine, whereas stromal cell-derived ADAMTS1 was the most robustly expressed VCAN-degrading protease. Purified versikine induced early expression of inflammatory cytokines interleukin 1b (IL-1b) and IL-6 by human myeloma marrow-derived MAMs. We show that versikine signals through pathways both dependent and independent of Tpl2 kinase, a key regulator of nuclear factor kB1-mediated MAPK activation in macrophages. Unlike intact VCAN, versikine-induced Il-6 production was partially independent of Tlr2. In a model of macrophage-myeloma cell crosstalk, versikine induced components of "T-cell inflammation," including IRF8-dependent type I interferon transcriptional signatures and T-cell chemoattractant CCL2. Thus the interplay between stromal cells and myeloid cells in the myeloma microenvironment generates versikine, a novel bioactive damage-associated molecular pattern that may facilitate immune sensing of myeloma tumors and modulate the tolerogenic consequences of intact VCAN accumulation. Therapeutic versikine administration may potentiate T-cell-activating immunotherapies. (Blood. 2016;128(5):680-685)

Background: Inflammation/ovulation-associated protein TSG-6 performs multiple functions in hyaluronan (HA)-rich extracellular matrices.Results: Inter-α-inhibitor (IαI) affects HA-TSG-6 interactions and enhancement of cell adhesion while promoting covalent complex formation between IαI heavy chains and HA.Conclusion: IαI dictates TSG-6 activity and remodels HA matrix properties.Significance: These results provide novel insights into the regulation of HA-protein interactions and assembly of biologically important extracellular matrices.

Background:The mechanisms of versican proteolysis by ADAMTS proteases are unknown. Results: The ADAMTS5 ancillary domain and specific chondroitin sulfate chains of versican are required for proteolysis. Conclusion: Docking between the ADAMTS5 ancillary domain and CS chains is a major mechanism underlying versican proteolysis. Proteolysis by ADAMTS1 has a similar requirement for GAG chains. Significance: The findings suggest strategies for blocking versican cleavage.

Versican is a widely distributed chondroitin sulfate proteoglycan that forms large complexes with the glycosaminoglycan hyaluronan (HA). As a consequence of HA binding to its receptor CD44 and interactions of the versican C-terminal globular (G3) domain with a variety of extracellular matrix proteins, versican is a key component of well-defined networks in pericellular matrix and extracellular matrix. It is crucial for several developmental processes in the embryo and there is increasing interest in its roles in cancer and inflammation. Versican proteolysis by ADAMTS proteases is highly regulated, occurs at specific peptide bonds, and is relevant to several physiological and disease mechanisms. In this chapter, methods are described for the isolation and detection of intact and cleaved versican in tissues using morphologic and biochemical techniques. These, together with the methodologies for purification and analysis of recombinant versican and a versican fragment provided here, are likely to facilitate further progress on the biology of versican and its proteolysis.