Midkine is a
heparin-binding
cytokine or a
growth factor with a molecular weight of 13 kDa.
Midkine binds to oversulfated structures in
heparan sulfate and
chondroitin sulfate. The
midkine receptor is a molecular complex containing
proteoglycans.
Midkine promotes migration, survival and other activities of target cells.
Midkine has about 50% sequence identity with
pleiotrophin. Mice deficient in both factors exhibit severe abnormalities including
female infertility. In adults,
midkine is expressed in damaged tissues and involved in the reparative process. It is also involved in inflammatory reactions by promoting the migration of leukocytes, induction of
chemokines and suppression of regulatory T cells.
Midkine is expressed in a variety of malignant
tumors and promotes their growth and invasion.
Midkine appears to be helpful for the treatment of
injuries in the heart, brain, spinal cord and retina.
Midkine inhibitors are expected to be effective in the treatment of
malignancies,
rheumatoid arthritis,
multiple sclerosis, renal diseases, restenosis,
hypertension and adhesion after surgery.