A heparin‐binding growth factor, midkine, binds to a chondroitin sulfate proteoglycan, PG‐M/versican

Abstract

Midkine is a heparin-binding growth factor with survival-promoting and migration-enhancing activities. In order to understand the regulation of midkine signaling, we isolated midkine-binding proteoglycans from day 13 mouse embryos, when midkine is intensely expressed. Deglycosylation followed by SDS/PAGE revealed various protein bands; one of these was identified as PG-M/versican by in gel trypsin digestion and sequencing the resulting peptides. PG-M/versican isolated from day 13 mouse embryos bound midkine with a K d of 1.0 nm. Pleiotrophin/ heparin-binding growth-associated molecule, which has a structure related to midkine, was also bound similarly. Digestion with chondroitinase ABC, AC-I or B abolished the binding to midkine. Heparin as well as chondroitin sulfate D and E inhibited the binding. After chondroitinase ABC digestion, the midkine-binding PG-M/versican released 4-sulfated, 6-sulfated, 2,6-disulfated and 4,6-disulfated unsaturated disaccharides. These results suggest that midkine binds to a polysulfated domain in the chondroitin sulfate chain with a region of dermatan sulfate structure. This proteoglycan may modulate the midkine activity, as binding to midkine can enhance midkine action by concentrating it to the cell periphery or inhibit the action by competing with the binding to a signaling receptor.

Chondroitin Sulfate Chains on Syndecan-1 and Syndecan-4 from Normal Murine Mammary Gland Epithelial Cells Are Structurally and Functionally Distinct and Cooperate with Heparan Sulfate Chains to Bind Growth Factors

“…To our knowledge, the direct binding of PTN to syndecan-4 is a new finding, although strong binding of MK to syndecan-1 (54), syndecan-3/N-syndecan (55), and syndecan-4/ryudocan (56) has been reported. Recent reports indicate that CS-PGs in the brain indeed bind MK and PTN: the high affinity binding of MK to protein-tyrosine phosphatase through the CS chain (57); the binding of MK and PTN to PG-M/versican isolated from E13 mouse embryos (58); and the high affinity binding (K d ϭ 0.25-3.0 nM) of PTN to phosphacan (59). The CS chain from appican (43) and the CS/dermatan sulfate chain from embryonic pig brain (39) are capable of binding MK and PTN in addition to bFGF, although the latter chains are assumed to be derived from various PGs.…”

Haptotactic Migration Induced by Midkine

“…Dextran sulfate, which has 1.5 sulfate residues per sugar residue, strongly inhibits MK-sulfatide binding (53). In the case of MK binding to PG-M/versican, a matrix chondroitin sulfate proteoglycan, disulfated disaccharides were identified (54). Furthermore, chondroitin sulfate E specifically inhibits MK-dependent neuronal cell adhesion (55).…”

“…Taken together, most probably the chondroitin sulfate chain in PTP, to which MK binds, has an oversulfated structure in a dermatan sulfate domain. Indeed, E-type structure with a dermatan sulfate domain was found in PG-M/versican, which was isolated from mouse embryos and has MK binding activity (54).…”

Versican Is Differentially Expressed in Human Melanoma and May Play a Role in Tumor Development

“…Regard-ing gliomas, a decrease of versican expression has been described in the extracellular matrix, whereas there is an up-regulation of versican in tumor vessels compared to normal cerebral vessels. 9 Because of its ability to interact with hyaluronate, 10 tenascin 11 and other proteins, and cytokines, [12][13][14][15] versican may contribute to the malignant properties of tumor cells. In this sense, it has been described that the versican-rich extracellular matrices exert an anti-adhesive effect on the cells, thus facilitating tumor cell migration and invasion.…”