Related Experiment Videos
A heparin-binding growth factor, midkine, binds to a chondroitin sulfate proteoglycan, PG-M/versican
K Zou1, H Muramatsu, S Ikematsu
1Department of Biochemistry, Nagoya University School of Medicine, Japan.
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 Kd 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.
Insights
Midkine, a growth factor, binds to PG-M/versican proteoglycans in mouse embryos. This interaction involves specific chondroitin sulfate structures and may regulate midkine
Area of Science:
- Developmental Biology
- Molecular Biology
- Biochemistry
Background:
- Midkine is a heparin-binding growth factor crucial for cell survival and migration.
- Understanding midkine's regulatory mechanisms is vital for comprehending its biological roles.
Purpose of the Study:
- To identify midkine-binding proteoglycans involved in regulating midkine signaling.
- To characterize the binding interaction between midkine and identified proteoglycans.
Main Methods:
- Isolation and identification of midkine-binding proteoglycans from embryonic mouse tissues.
- Biochemical analysis including deglycosylation, SDS-PAGE, in-gel trypsin digestion, and peptide sequencing.
- Binding assays (Kd determination) and enzymatic digestion (chondroitinase) to analyze interaction sites.
Main Results:
- PG-M/versican was identified as a midkine-binding proteoglycan in embryonic mouse tissues.
- Midkine bound PG-M/versican with high affinity (Kd = 1.0 nM).
- Binding was dependent on the chondroitin sulfate chains of PG-M/versican, specifically involving sulfated domains.
Conclusions:
- Midkine interacts with PG-M/versican via its chondroitin sulfate chains, likely involving dermatan sulfate structures.
- This proteoglycan interaction may modulate midkine activity, either by enhancing its action or by competing with receptor binding.
- PG-M/versican acts as a potential regulator of midkine signaling during embryonic development.